Over the past decades, graphene has attracted much attention from the scientific community due to its broad applications in the optoelectronics industries We fabricated a vertical photovoltaic type G/PbS/Ti device by making use of the Ti/PbS Schottky junction and discussed the photocurrent transient characteristics. Lead sulfide (PbS) was deposited directly on large area CVD  graphene by CBD . Temperature dependent photocurrent spectra of our G/PbS/Ti photovoltaic devices were measured by a Fourier transformed infrared (FTIR) set-up.In this paper, we present the experimental procedures and the raw experimental data for the direct chemical deposition of PbS on CVD-graphene for high performance photovoltaic infrared photo-detectors. The manuscript is already available  Specifications Table•Graphene tends to peel off from glass substrates when immersed in solutions containing chemicals such as NaOH. These data are important as we describe direct deposition of PbS on graphene from a solution containing 570 mM of NaOH. The deposition was successful after the annealing of graphene/glass.•Scientific researchers who want to chemically synthesize materials directly on graphene can benefit from our data.•These data can be helpful for further studies using graphene and PbS for flexible infrared devices taking advantage of the high transmission of graphene in the infrared spectral range.•We provide detailed experimental processes for direct chemical synthesis of PbS on graphene.•Photocurrent transient behaviours have been attributed to the accumulation of photo-generated carriers at interfaces and back injection of the carriers. These explanations can be extended to the photocurrent transient behaviours of other heterostructures.1This work presents a step-by-step procedure and the raw experimental data for direct deposition of PbS on large area CVD-graphene for high performance photovoltaic infrared photo-detectors. This article provides all the raw data in reference In this paper, we show a schematic diagram for the deposition of PbS films in supplementary figure S1(a). Mobility data for PbS/graphene/glass are given in S1(b). The observed high mobility values of the films on graphene indicate that majority carriers (holes) of PbS films flow through graphene.23)2, 99.3%; Kanto Chemical Co., Ltd., Japan), for Pb source, 90 mM thiourea (CS(NH2)2, 98%; Kanto Chemical Co., Ltd., Japan) for S source and 570 mM sodium hydroxide  as complexing agent. Using a Teflon beaker containing 100 ml deionized water, NaOH bids were first put in, shortly after which Pb (NO3)2 was added to the solution and stirred using a magnetic stirrer for 10 min. CS(NH2)2 was added to the solution and finally the substrates were immersed vertically in the solution. The deposition was done at room temperature conditions and stirred at 180 RPM. The deposition time was 1–2 h PbS films were produced by chemical bath deposition (CBD) method using 180 mM lead nitrate  under 560 mTorr for about half an hour, followed by rapidly cooling the film to room temperature (10°C min−1) under flowing H2 under 90 mTorr. The graphene/Cu film was coated with a thin layer of poly methyl methacrylate (PMMA). The Cu foil under the graphene was etched away in an aqueous solution containing 0.1M ammonium persulfate. After washing with deionized water several times, the PMMA/graphene was transferred onto a microscope slide glass substrate A single layer of graphene was grown on a copper foil using CVD method. First, the Cu foil  was loaded into a quartz tube of the CVD system and annealed at 1000°C under 90 mTorr with flowing 10 sccm of HWe successively deposited 1–5 layers of graphene on the microscope slide glass by the PMMA assisted layer-by-layer transfer process. To improve adhesion between graphene films and glass substrates, the substrates were thermally annealed to remove all residual PMMA. We learned that post-annealing was important for the adhesion of PbS films on graphene/glass. Graphene/glass were annealed at 600 °C for 2 h. An e-beam evaporator with a metal mask was used to deposit Ti electrodes on PbS/graphene/glass.The authors declare that they have no known competing financial interests or personal relationships which have, or could be perceived to have, influenced the work reported in this article.


In order to evaluate the incorporation of the amino group into the mesopore channels, thermal and structural analysis were made through Thermogravimetric Analysis (TGA), nitrogen adsorption–desorption at 77 K by Specific Brunauer–Emmett–Teller (SBET) method, Fourier Transfer Infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and X-Ray Photoelectron Spectroscopy (XPS). The higher Pb(II) ions removal was achieved with the 0.3 molar proportion of xNH2/DMS-1 reaching 99.44% efficiency. This result suggests that the functionalized material can be used as an efficient adsorbent for Pb(II) ions from aqueous solution.Water pollution by heavy metals represents several health risks. Conventional technologies employed to eliminate lead ions from residual or drinking water are expensive, therefore an efficient and low-cost technique is required and adsorption processes are a good alternative. In this work, the goal was to determine the adsorption capacity of a Disordered Mesoporous Silica 1 material (DMS-1) functionalized with amino groups, for Pb(II) ions removal. DMS-1 was prepared by sol-gel method and the incorporation of amino groups was performed by ex-situ method. As the source of amine groups, (3-Aminopropyl) triethoxysilane (APTES) was used and three different  Lead is a heavy metal that has produced considerable interest due to the health risks it causes, even at low concentrations ,2. Due t2/g) and has a spherical pore shape with a wormhole morphology [2 groups to promote an accurate mass transfer in the pore network of NH2/DMS-1. There are several techniques to remove lead ions from drinking water and wastewater, the most common being filtration, ion exchange and reverse osmosis ,17. Howerphology ,32. In prphology , like NHThe influence of the sorbent morphology on its sorption capacity is well known. For example, it was found that the initial adsorption rate onto platelet mesoporous adsorbents was rapid and faster than the rates of rod-like and fiber-like morphologies . However2⋯Pb(II) structures [The adsorption of Pb(II) cations by mesoporous silica functionalized with amino groups has been investigated previously ,38,39,40ructures ,36.xNH2/DMS-1 exhibits an open pore structure and accessible adsorption sites, there are necessary conditions for a good contact between the lead ions and the adsorption sites. In addition, to evaluate the Pb2+ adsorption in the functionalized DMS-1, structural characterization by Fourier Transform Infrared Spectroscopy (FTIR) spectra, N2 adsorption-desorption isotherms, X-Ray Diffraction (XRD), Thermogravimetric Analysis-Derivative Thermogravimetry (TGA-DTG), and X-Ray Photoelectron Spectroscopy (XPS) were performed. It has been demonstrated that the main advantage of the DMS-1 sorbent was the stability of their -Si–O–Si– bonds formed between the amino and the hydroxyl groups on silica surface. Although it is commonly believed that the more amino groups bonded to the silica surface the better cations removal from an aqueous solution, the results presented in this work shows that ammonia content should be optimized to obtain the maxima of lead removal. It was concluded that the amino-functionalized DMS-1 adsorbents should be interesting and promising sorbents for heavy metal ions removal from aqueous solutions.Within this scenario, the aim of this study was to develop an effective adsorbing system made of DMS-1 functionalized with amino groups to remove Pb(II) ions from aqueous solutions. To attain this, the following conditions were optimized to perform the adsorption: concentration of amino group, contact time, initial pH, and temperature, regarding the effectiveness for the Pb(II) removal. Taking into account that the 106–PO70–EO106, 99%, Aldrich) was used as the surfactant and tetraethyl orthosilicate  as the silica source. In a typical synthesis procedure, the triblock copolymer was dissolved in a mixture of deionized water and 2M hydrochloric acid  solution, and the mix was stirred for 1 hour, after that time, the required quantity of TEOS was added to the mixture at 30 °C and it was kept under magnetic stirring for 24 h. The mixture was subsequently transferred to polypropylene bottles and they were heated at 80 °C for 48 h. Then, the obtained solid was filtered, washed with deionized water, dried at 110 °C for 18 hours and finally, it was calcined in an air atmosphere at 550 °C for 4 h to remove the organic molecules [Disordered Mesoporous Silica 1 (DMS-1) was synthesized according to the sol-gel method proposed by Zhao (1998) and Fuertes (2004) ,42. The olecules .2(CH2)3Si(OEt)3, 99%, Aldrich) in ethanol  [2-modified samples were labeled hereafter as 0.2 NH2/DMS-1, 0.3 NH2/DMS-1, and 0.4 NH2/DMS-1. One gram of DMS-1 was dispersed into a solution made of APTES-ethanol for 30 min at 30 °C. After that time, deionized water was gradually added and lastly, the liquid suspension was put to stirr for additional 30 min at 30 °C. Water was incorporated in order to perform hydrolysis of the alkoxide groups of APTES. The added water amount was twice the amount required to completely hydrolyze the APTES content. Finally, the solids obtained were dried at room temperature and posteriorly at 50 °C for 24 h.The functionalization of the internal surface of mesopores in DMS-1 has been achieved by the ex-situ method. The amino groups were attached to the internal mesoporosity in DMS-1 using a solution of 3-Aminopropyl-triethoxysilane (APTES NHAldrich) . The matThe efficiency of the amine-functionalized DMS-1 materials to remove Pb(II) ions from water was determined by a batch technique. To evaluate this removal efficiency, 20 mL of 100 mg/L Pb(II) aqueous solutions were put in contact with 0.1 g of the adsorbent material. The Pb(II) solution was prepared with a Pb standard .The effects of contact time, pH , the temLead (II) ions concentration was determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES), in water samples taken before and after adsorption experiments. The effects of the parameters listed above on the adsorption capacity for functionalized DMS-1 and bare DMS-1 were evaluated. Determination of Pb(II) ions concentration was performed in an Optima 8300 spectrometer . The emission lines were used according to the standard Environmental Protection Agency (EPA) method to analyze this metal . Adsorbe−4 mbar) to ensure a clean, dry surface free of any loosely adsorbed species. The specific areas (SBET) of the samples were calculated via the standard Brunauer–Emmett–Teller (BET) procedure [0 < 0.3. The total pore volume (Vp) was estimated from the amount of nitrogen adsorbed at a 0.99 relative pressure [The mesoporous materials were studied to know their textural properties by the nitrogen adsorption isotherms registered at 77 K using a volumetric Autosorb-IQ2 adsorption analyzer  . Before rocedure  using thpressure ,49,50. Tpressure . The thepressure ,53 using−1. Pore arrangement on DMS-1 was analyzed by low-angle X-Ray Diffraction (XRD). XRD diffractograms were obtained with a Rigaku Ultima IV diffractometer  using Cu Kα (λ = 1. 5406 Å) radiation [−8 mbar. The binding energy was determined using the carbon C(1s) line as a reference with a binding energy of 284 eV [The functional groups on the amine-functionalized adsorbents were studied by an Infrared Spectrum Two spectrophotometer  ,55,56,57adiation  in the 2adiation ,60. X-Raf 284 eV . The staf 284 eV .2/DMS-1 are shown in 0 is a H1 type, distinctive from materials with pore diameters between 6 and 8 nm, and is typical for wormhole structured DMS-type materials [2/DMS-1 showed a decrease in the desorption first stage, suggesting that the NH2 groups are attached to the internal surface of the DMS-1 pores. Textural properties were obtained from the nitrogen adsorption-desorption isotherms. Specific surface area, total pore volume, and average pore size were determined for all samples. Nitrogen adsorption-desorption isotherms for the bare DMS-1 and 0.3NHaterials . The iso2/DMS-1 samples showed a uniform and narrow pore size distribution, which had average size values of about 6.5 and 5.6 nm, respectively. This result corroborates that the modification reaction of DMS-1 using a molar concentration of 0.3 of APTES did not produce significant damage to the structure of the material. Therefore, the surface area and the total pore volume of the modified material reduced their values significantly compared to those determined for the pure DMS-1. The decrease in the pore volume value in the 0.3NH2/DMS-1 is a consequence of the functionalization process. The nitrogen adsorption–desorption study also confirms that the analyzed samples are DMS-type materials.Texture properties from the materials are summarized in 2/DMS-1, 0.3NH2/DMS-1 and 0.4NH2/DMS-1 materials. For the DMS-1 sample, two Bragg reflections were observed at the values of 0.02° and 0.34°, which indicate there are two different pore sizes repeated in the mesh structure, corresponding to pores formed among particles (0.02°), and the textural pores; both in the mesopore range. The functionalized materials 0.2NH2/DMS-1, 0.3NH2/DMS-1 and 0.4NH2/DMS-1 showed similar Bragg reflections at 0.02° and about 0.34°. However, the reflections about 0.34° suffered a slight displacement toward smaller angle values, their intensity and width increased as a function of the amino group concentration. For 0.4NH2/DMS-1 adsorbent, this reflection was shorter and thinner than that corresponding to 0.3NH2/DMS-1; these differences could be produced by saturation of functionalizing molecules in the open side of pores, complicating the diffusion of these molecules within the pore.2/DMS-1 material are shown in SEM images of the 0.3NH−1 are clearly visible, which are related to the asymmetric and symmetric stretching vibrations of Si–O–Si bonds, respectively [−1 band could be associated with stretches of Si-O- or Si-OH groups, probably hydrogen-bonded to adsorbed H2O molecules. The band at 1631 cm−1 is correlated to the O–H deformation bending vibration of physically absorbed water. The broad band centered at 3400 cm−1 is due to silanol groups having cross hydrogen bonding which interacts with the adsorbed water molecules [−1) of methylene groups [−1 in the range of 2700–3400 cm−1 is attributed to NH2 stretching vibration. Noticeably, the 0.3NH2/DMS-1 exhibits higher intensity of this band than 0.4NH2/DMS-1 counterpart suggesting the largest surface exposure of NH2- groups. The weak N–H bending vibration at 950 cm−1 and the symmetric –NH2 bending vibration around 1561 cm−1, confirms the incorporation of amino groups [The FTIR spectra of pure DMS-1 and the adsorbent materials with different amino concentration are displayed in ectively ,68,69,70olecules ,72. It ie groups ,74. In to groups .2/DMS-1, 0.3NH2/DMS-1 and 0.4NH2/DMS-1 mesoporous materials are shown in 2/DMS-1, 0.3NH2/DMS-1 and 0.4NH2/DMS-1 samples exhibit weight losses of 19.93%, 21.04% and 21.04% respectively. The profiles  with 99.44% removal. Thus, although it is commonly believed that the more amino group bonded to the silica surface the better cations removal from an aqueous solution, the results presented in this work shows that amount of amino groups should be optimized to obtain the maxima of lead removal.In order to establish the appropriate adsorption conditions for Pb(II) removal with amine-functionalized materials, several tests were made at natural pH and 30 °C for 1 h. The adsorption of Pb(II) ions for each adsorbent 0.2NH2/DMS-1) was studied by a batch operation, the experiments were performed to determine the effects of contact time, the pH value, adsorption temperature and initial lead ion concentration in solution. The effect of contact time on the removal efficiency of Pb(II) within the range from 0 to 60 min under pH 5 at 25, 30 and 35 °C is observed in The adsorption of Pb(II) ions by the selected adsorbent  but more PbOH+ species are present in the solution [2 occur and precipitate in solution with pH > 6 [2/DMS-1 for Pb (II) adsorption was improved with an increase of the pH of solution from 2 to 5. Taking in mind that the surface of bare silica is acidic due to presence of silanol groups (its isoelectric point (IEP) is close to pH 2) whereas the surface of the silica grafted with aminopropyl groups is more basic [2+ cations on the negatively charged surface of adsorbate increases above the PZC point of this adsorbate. Thus, the possible explanation of an increase of Pb(II) removal with an increase of pH of solution are two: (i) the amount of protonated amino groups decreased (–NH2 groups) due to their de-protonation forming negatively charged sites, and/or (ii) the higher electrostatic attraction at pH of 5. At higher pH, the surface of 0.3 NH2/DMS-1 has a negative charge because of the high concentrations of –OH ions in the aqueous solution, favorable for the adsorption of Pb(II). Considering the study by Huang et al. [2+ and Pb(OH)+ species are dominant species at pH < 6 and pH > 7.5, respectively. The hydrolysis of Pb2+ to form Pb(OH)+ and Pb(OH)2 occurs at pH 3.7 and 6.8, respectively. Therefore, the best removal of lead by 0.3NH2/DMS-1 was performed at pH = 5.The influence of the pH on the adsorption capacity was studied and the results are exposed in solution . The speh pH > 6 ,80, whicre basic , the depg et al. , the Pb2xNH2/DMS-1 can be explained considering the attachment of ligands as the point-wise linkage to the silica surface, while at higher molar proportion of amino groups (xNH2/DMS-1) the amino groups are attached as the loop structures bonded with the silica, as shown as shown in The optimization of the DMS-1 surface archived with the 0.3 molar proportion of 2/DMS-1 under pH 5 for 60 min, the removal efficiency increased gradually with the rise of temperature from 25 to 30 °C, but decreased from 99.57% to 98.63% with the intensification in the temperature from 30 to 35 °C. This decrease suggests that the adsorption process is exothermic. The study reveals that the adsorption process of heavy metal ions was improved at 30 °C possibly by the exothermic electrostatic interactions [ractions .2/DMS-1 adsorbent was investigated. The effect of initial metal concentration on the adsorption rate was analyzed within the range 10–500 mg/L at pH 5 and 30 °C for 60 min, as shown in 2/DMS-1 could be effectively realized using acid treatment, as it was demonstrated for ZnCl2-MCM-41 sorbent regenerated with HNO3 [In order to explain the mechanism responsible for Pb(II) removal from aqueous solutions by adsorption on functionalized siliceous DMS-1 materials, the effect of the initial concentration of Pb(II) ion adsorption on the most optimized 0.3 NHith HNO3 . Similarith HNO3 .2/DMS-1 adsorbent was examined by the XPS wide-scan spectrum in 2/DMS-1 sample before and after lead ion adsorption from the solution containing 100 ppm of Pb(II) ions. The binding energies of Si2p, C1s, O1s, N1s, and Pb4f7/2 core electrons and surface atomic ratios (N/Si and Pb/N) are compiled in 2 and protonated -NH3+ bonds respectively. These species were detected before Pb(II) adsorption and also after adsorption, although the –NH2 gets protonated, there are still enough concentration of -NH2 able to coordinate with the Pb2+ ions over the pair of free electrons. The atoms of nitrogen located in the surface of the silicon resulted in an atomic ratio of 0.13, and the Pb/N revealed an atomic ratio of 1.38.The most effective adsorbent was studied by XPS techniques to elucidate the nature of adsorption sites. The introduction of the Pb(II) ions onto 0.3NH2/DMS-1 showed two peaks (Pb4f7/2 and Pb4f5/2) resultant from a spin-orbit doublet. Identifying the Pb4f7/2 core level, the binding energy at 138.17 eV was observed and it is higher than those reported for the orthorhombic PbO compound (137.2 eV) and more similar to the binding energy reported for Pb(NO3)2 (138.6 eV) [7/2 during adsorption. 38.6 eV) ,91,92. T2/DMS-1 systems with groups amino to remove Pb(II) ions from aqueous solutions were studied. The affinity between the synthesized materials and the heavy metal is attributed to their atomic properties and to the pH value from the solution. The optimum pH values for the removal of the lead ions by 0.3NH2/DMS–1 material were pH 4 to 6. Lead adsorption on amino-modified DMS-1 materials may be explained by the Van der Walls electrostatic interactions between the Pb(II) ions and the -NH2 surface.NH


Graphite nanoplatelets (GNPs), a functional 2D nanofiller for polymer nanocomposites, utilize natural graphite as a raw material due to its stacked graphene layers and outstanding material properties upon successful exfoliation into nano-thick sheets. However, the increasing demand for natural graphite in many industrial applications necessitates the use of graphite from waste resources. We synthesized GNPs from waste chicken feathers (WCFs) by graphitizing carbonized chicken feathers and exfoliating the graphitic carbon by high-speed homogenization and sonication. We then separated GNP from non-exfoliated carbon by centrifugation. This paper describes the morphology, chemical, and crystalline properties of WCF and its carbon derivatives, as well as the structural features of WCF-derived carbons. We obtained GNPs that have a 2D structure with huge variations in particle size and thickness. The GNP shows the presence of carbonyl groups, which are mostly attached at the edges of the stacked graphene sheets. Defects in the GNP are higher than in graphene synthesized from direct exfoliation of natural graphite but lower than in graphene oxide and reduced graphene oxide. To produce GNP of high quality from WCF, restacking of graphene sheets and concentration of carbonyls must be minimized. With their commercial availability, low cost, and structure similarity to graphene, graphite nanoplatelets (GNPs) continue to be a significant component of modern polymer nanocomposites ,3,4,5,6.GNPs have been prepared previously, using different methods ,8, but t6 t annually [6 t of WCFs every year [To contribute to this effort, we have prepared GNPs from carbonized and graphitized waste chicken feathers (WCFs). Recently, carbon-based nanomaterials have been produced from WCFs ,35 and, annually . Worldwiery year . While tery year . The masery year . Howeverery year ,46. This3·6H2O  were used in the graphitization of CCF. Moreover, 2-propanol  and deionized water were utilized as a solvent during high-speed homogenization of GCF. WCFs were obtained from a poultry processing plant in Bulacan, Philippines. Hydrochloric acid  and FeClWCFs were washed several times with water mixed with liquid detergent, to remove blood, manure, and other unwanted components. The washed WCFs were laid out on galvanized iron sheets and sun-dried for 3 days. WCFs were further conditioned in a laboratory oven  at 105 °C for 24 h before being cut into ~10 mm long pieces. After manually separating the rachis, the barbs were cut into ~2 mm long fibers and milled in an analytical mill  for 10 min. The resulting WCF powder was sieved (mesh 100) before carbonization.3·6H2O  were added to distilled water (100 mL g−1 CCF). The pH of the solution was adjusted ~2 by adding HCl. The mixture was heated at 60 °C for 5 h, using a hot plate , while being continuously homogenized at 1000 rpm by a high-speed homogenizer  equipped with a dispersing element . GCF was separated from the homogenized solution by vacuum filtration and dried in a laboratory oven at 105 °C for at least 48 h before further use.The carbonization and graphitization of WCF were performed by following the method of Akhavan et al. . Briefly−1, as measured by drop-casting and drying until constant weight. The yield of GNP from GCF was 4.8 wt%.To prepare GNP, 10 g GCF was added to 1000 mL of 40 wt% 2-propanol aqueous solution and was subjected to high-speed homogenization at 5000 rpm for 90 min. The homogenized solution was probe sonicated  under an ice bath at amplitude 80 for 90 min. GNP was separated from non-exfoliated GCF by centrifugation  at 500 rpm for 120 min. The upper 30 mL of the centrifuged mixture was pipetted to several watch glasses and dried in a hot plate at 100 °C, to recover the brown GNP powder. The concentration of GNP in the pipetted solution was estimated to be 0.6 mg mLμm scan size. Analysis of line profiles was performed by using XEI software . The particle size distribution of GNPs was determined by using ImageJ software . The morphologies of WCF, CCF, and GCF were examined by using a scanning electron microscope  operated at 2 kV. The samples were mounted on a carbon tape placed on an aluminum stub. A small amount of GCF was diluted in ethanol, drop-casted, and dried in a sample stub before viewing in a field emission transmission electron microscope  operated at 200 kV. GNP solution was drop-casted and dried in a clean glass slide before examining in an atomic force microscope  at non-contact mode. Two-dimensional images were generated at 10 × 10 −1 and resolution of 4 cm−1. The background spectrum was obtained without the sample prior to the actual measurements.The chemical structures were studied, using a Fourier transform infrared spectrometer  coupled with a diamond/ZnSe attenuated total reflectance (ATR) crystal plate accessory. Four scans were accumulated for each measured spectrum, with a range of 650–4000 cmα radiation (λ = 0.154 nm) at 30 kV and 10 mA. Diffraction patterns were recorded from 2θ = 5°–80°, with an increment of 0.04°. Moreover, d-spacing and stacking height (cL) of graphitic carbon detected in GNP and GCF were determined by using Bragg and Scherrer equations [θ = 10–40°, using GRAMS/AI software. Impurities in CCF were determined by X-ray fluorescence  operated at 25–50 kV and 200 μA for an analysis area of 1 mm.The crystallinity of the samples was analyzed by X-ray diffraction , using Cu-Kquations . The Bra−1 and analyzed by using GRAMS/AI. After manual baseline correction, curve-fitting was performed by using the Levenberg–Marquardt algorithm. The spectra were deconvoluted, using Gaussian functions, and best-fitted with 5 bands.Raman spectra of carbon samples were taken on a micro-Raman spectrometer  with a 50 mW, 532 nm diode laser for excitation. Raman spectra were recorded from 800 to 2000 cmThe morphology of WCF a shows a3·6H2O g−1 CCF and 0.0001–0.001 mol Fe(NO3)3·9H2O g−1 sawdust in [High-speed homogenization applied during graphitization of CCF to produce GCF decreased the particle size a. Moreovwdust in , and theThe liquid-phase exfoliation of GCF to yield GNP resulted in 2D nanomaterials of varied particle sizes and thicknesses . Most of−1) [−1) and Amide II (1533 cm−1) [−1), which was eliminated after its exfoliation and drying to produce GNP.The chemical structure of GNP  indicate−1) ,55. The −1) . The car−1) ,57. Carb33 cm−1)  in the kθ = 25°) in their crystalline structures , resulting from the mild evaporation of intercalated H2O molecules during thermal annealing of GNP at 100 °C [Lc than GCF  as a result of restacked graphene sheets due to thermal annealing [Both GNP and GCF show a graphite-like arrangement , and CaCO3  [2 and Na2CO3 in detergent [α-helix (10.2°) and β-sheet (20.7°) crystal structures of peptide chains in WCF [CCF also shows graphitic ordering, as observed previously for pyrolyzed feathers . Other dd 32.6°) ,64. Resuetergent  have rems in WCF .−1) for the in-plane bond stretching motion of sp2 carbon; the D1 band (1339 cm−1) for the in-plane breathing vibration of sp2 carbon within structural defects; the D3 band (1433 cm−1) for the amorphous sp2 carbon; and the D4 band (1224 cm−1) for the sp2-sp3 bonds or C-C and C=C stretching vibration in polyenes [−1) denotes an artifact of the instrumental setup and is not related to the carbon samples [I/ITotal). In all the samples, the G and D1 bands have the largest band areas as compared to the other bands. The FWHMs of G (154.0–167.7 cm−1) and D1 (128–140.4 cm−1) bands are larger than in natural and synthetic graphites  but comparable to graphene oxide  and thermally reduced graphene oxide  [θ = 11° for graphene oxide  . This cone oxide , the carIG/ITotal > ID1/ITotal). GNP has the lowest ID1/IG ratio, i.e., GCF (0.75) > CCF (0.71) > GNP (0.56), meaning that it has the lowest number of defects [ID1/ITotal. The defect content of GNP is higher than most graphene reported in the literature, e.g., ID1/IG < 0.18 [ID1/IG > 1 [ID1/IG of GCF, as well as the narrower FWHM of the G band and higher IG/ITotal, compared to CCF, can be attributed to the defects brought by the growth of graphitic tubules on the surface of CCF.All carbon samples show a well-ordered graphitic structure  carbonize WCF to produce CCF; (2) graphitize CCF at low temperature and acidic conditions, using an iron catalyst to generate GCF; (3) homogenize and sonicate GCF, to exfoliate the graphitic carbon; and (4) separate the exfoliated graphite from non-exfoliated carbon by centrifugation to yield GNP. The obtained GNPs are 2D nanomaterials of varied particle size and thickness. The GNP has carbonyl groups attached at the edges of the stacked graphene sheets. Defects in GNP are higher than in graphene prepared from direct exfoliation of natural graphite but lower than in graphene oxide and reduced graphene oxide. To consider WCF as a sustainable source of graphite for high-quality GNP, further research is needed to lessen restacking of graphene sheets, lower the concentration of carbonyl groups, and reduce the defects in the GNP.


An uncoated fibre is employed to compensate for bending losses that are likely to occur during movement. A linear fit to the response of the sensing system to RH demonstrates a sensitivity of 3.02 mV/% (R2 = 0.96), hysteresis ± 1.17% RH when 11 bilayers of PAH/SiO2 NPs are coated on the tip of the fibre. The performance of two different textiles (100% cotton and 100% polyester) were tested in real-time relative humidity measurement for 10 healthy volunteers. The results demonstrate the moisture wicking properties of polyester in that the relative humidity dropped more rapidly after cessation of exercise compared to cotton. The approach has the potential to be used to monitor sports performance and by clothing developers for characterising different garment designs.An optical fibre sensor for monitoring relative humidity (RH) changes during exercise is demonstrated. The humidity sensor comprises a tip coating of poly  (PAH)/silica nanoparticles (SiO Humidity, the amount of water vapour in the air, is an important indicator relating to human comfort and performance during work and sport. Tsutsumi et al. reported that low indoor humidity level has positive effects on human wellbeing, however, when the humidity reaches above 70% RH, subjects reported to be more tired . In spor® trans-epidermal water loss  was used as a reference. It is suggested that a distributed body network could be established to provide valuable information for improving athletes’ physical performance.The relationship between comfort, performance and humidity has inevitably led to a wide range of different materials being developed by textile and clothing manufacturers . ISO 1542 nanoparticles based optical fibre sensors show fast response time and appropriate RH range for measurement [Compared to electronic humidity sensors, an optical fibre sensor (OFS) offers several advantages such as light weight, miniature size, flexibility, simple configuration and insensitivity to electromagnetic fields . The diasurement .Previous research has shown different biomedical applications of RH measurements such as skin microenvironment  and brea2 NPs thin film for measurement of relative humidity and the other is a bare fibre used as a reference for bending losses compensation during exercise. Different tee-shirts are investigated: 100% cotton where the material will adsorb moisture and 100% polyester which has well known moisture wicking properties. These were selected to demonstrate that the properties of the fabric can affect humidity rather than to demonstrate the well-established differences between a natural and a synthetic garment.In this paper, an optical fibre sensing system is developed and applied for RH measurement during sports activity (in this case a cycling test). Each sensor consists of two optical fibres. One with Poly /SiO2 NPs, diameter 40–50nm) were purchased from Nissan Chemical, Japan. Deionised water (DI water), having resistivity of 18.2 megohm, was obtained from a water purification system .Potassium hydroxide (KOH), Sodium hydroxide (NaOH), Ethanol and Poly   were purchased from Sigma-Aldrich, UK. Silica Nanoparticles (SiO2 NPs coating and a reference fibre (REF) without any coating. The end of each fibre was perpendicular cleaved. Two fibres are tightly surrounded by a 900 µm furcation tube  and heat shrink tubing  for protecting the tip from mechanical damage. Two pairs of sensors are used in this study.The sensing probe is composed of two optical fibres  which are an optical fibre humidity sensor (OFHS) with PAH/SiO2 NPs was coated on the tip of an optical fibre using the Layer-by-Layer self-assembly method [2 NPs solution for 15 min. (b) and (c) processes were repeated to achieve the required thickness. The coated optical fibre was dried at room temperature in the laboratory for 24 h before use. For the layer by layer technique, the thickness of each layer is approximately equal to the diameter of SiO2 NPs i.e., a 40–50 nm/monolayer. To determine the optimum film thickness, sensors with 3, 7 and 11 layers were prepared. A thin film composed of PAH/SiOy method . The fab2 NPs coated optical fibre sensor has been described previously [2 NPs is approximately 1.22 and the intensity changes linearly with RH [The humidity sensing mechanism of a PAH/SiOeviously . The tot with RH .α) between two separate optical fibres from one batch are identical [Meanwhile, water vapour does not easily adhere to the smooth tip surface of the uncoated bare fibre, which means that the bare fibre with perpendicular cleaved tip has the potential to be a reference for reducing bending loss effect. Ideally, under the same bending conditions, the intensity-loss coefficients  is the intensity measured from the reference fibre at θ = 0 which can be made before measurements commence. As the (unknown) bending angle θ is the same in both reference and sensing fibres, α is then used to compensate the humidity sensing channel.OFSI is the intensity measured from the sensing optical fibre. In this work, the intensity change due to bending of the OFHS is compensated using a reference fibre. We define a term 2 NPs was imaged using a transmission optical microscope . The morphology of the functionalised fibre tip was studied using scanning electron microscopy (SEM) . The fibre before and after coating with PAH/SiOA climatic chamber  was used in the calibration process. According to the temperature humidity control range, 2 NPs bilayers were tested.The sensor response has previously modelled as linear ,20 and sFor verification, the sensing probe and commercial humidity sensor were placed 0.5 cm apart inside the climatic chamber. Using the calibration curve obtained from RH calibration experiment, the output signal from the sensing probe was confirmed in terms of RH unit. Thus, the RH in the climatic chamber was set from 55% RH to 95% RH and reversed with two cycles. In order to observe the performance in sports activities of the optical humidity sensing system, a cycling experiment was performed. 10 volunteers  participated in the cycling test using an indoor cycle  at room temperature (22 ± 1 °C). Each volunteer wore two sports T-shirts with different materials (100% cotton and 100% polyester) separately for the same cycling test. The two cycling tests were separated by 45 min in order to stabilise the physical condition of volunteers. All the T-shirts were laundered and conditioned in the lab for 24 h before testing. Ethical approval was provided by the Ethics Committee, Faculty of Engineering, University of Nottingham. In order to observe the performance in sports activities of the optical humidity sensing system, a cycling experiment was performed. 10 volunteers  participated in the cycling test using an indoor cycle  at room temperature (22 ± 1 °C). Each volunteer wore two sports T-shirts with different materials (100% cotton and 100% polyester) separately for the same cycling test. The two cycling tests were separated by 45 min in order to stabilise the physical condition of volunteers. All the T-shirts were laundered and conditioned in the lab for 24 h before testing. Ethical approval was provided by the Ethics Committee, Faculty of Engineering, University of Nottingham. The commercial humidity sensor BME280 was also used for verification of the signal from the optical fibre humidity sensor. BME280 and OFHS were embedded in a 3D-printed holder  is broadly repeatable and inversely proportional to the RH change measured by the commercial humidity sensor (black curve). Comparing the dynamic light changes of OFHS with different layers , 2 thin film. For all sensors, the light intensity change was observed to exhibit an approximately linear dependence on the change of RH (50–80%). It can be observed that the greater the number of layers leads to an increase in the sensitivity of the OFHS. For the sensor with 3 layers (red line), the sensitivity was 0.40 mV/% RH (R2 = 0.95), for 7 layers (dark blue line), the sensitivity was 0.96 mV/% RH (R2 = 0.88) and for 11 layers (orange line) the sensitivity increased to 3.02 mV/% RH (R2 = 0.96). The hysteresis value is ±1.17% RH for 11-layers humidity sensor. The hysteresis is defined as the difference between measurements of the humidity increase/decrease branch and the averaged curve of both branches, the sequence 50-85-50% RH is used as shown in the The RH results obtained from the developed OFHS with 11 layers and commercial sensor can be compared in In order to investigate the bending response of the sensor, the 11 layer sensing probe was further tested using the set-up shown in Cotton is a hydrophilic material and polyester has hydrophobic property ,27. It cpeak) of inner and outer sensors from the OFHS for volunteers wearing 100% cotton and 100% polyester T-shirts. As can be seen from peak readings with polyester were smaller than that in the cotton group. This confirms the performance of polyester as a moisture wicking material [material .The developed sensing system has enabled relative humidity to be measured during exercise. Due their flexibility and small diameter , optical fibre sensors can be easily integrated within textiles with the potential to form next generation smart garments. They are more unobtrusive than commercial electronic humidity sensors but, for future widespread use, need to be competitive on cost. The prototype demonstrated in this paper comprises several components such as an SLD, fibre optic coupler and optical switch that would limit its use to a laboratory-based testing tool. However, for widespread use in wearable sensing the system could be simplified and reduced in cost. For example, multiple LEDs and photodiodes could be used to replace the SLD and optical switch. The bill of materials for a single channel system with wireless electronics is estimated to be ~€25 with the most significant cost a wireless microcontroller. As with most electronics systems, this cost would reduce with higher volumes.The system is robust to motion artefacts due to the inclusion of a reference fibre that can be used to compensate for bending losses as shown in 2 = 0.96). In line with previous research ,29 a linThe measurement unit is currently a bench top system with a trailing optical fibre between it and the subject. In certain applications e.g., climatic chamber or treadmill exercise, this is not a significant problem, although bending losses will increase due to the long optical fibre cable between subject and measurement unit. However, for measurements on the field of play or workplace, a wearable unit with wireless communications is desirable. The instrumentation utilised here is relatively simple and compact, and so miniaturising the measurement unit will be a focus of future work. The system currently measures RH on the inside and outside of a garment at a single position but due to the small size of the sensors there is potential to increase this by increasing the number of sensors and number of channels on the optical switch, for example, 16 is likely to be deployed in the next version of the device. The system has been tested on two garments with well-known and different properties (100% cotton and 100% polyester). The aim was to demonstrate the potential of the sensor and not to characterise the materials. Future tests will investigate different materials, structures and multiple garment layers.2 nanoparticle film was used to measure changes in light intensity reflected from the tip of the fibre which are proportional to humidity. Bending losses were partially compensated by including an uncoated reference fibre which enables measurements to be made during exercise. A new approach to monitoring humidity in garments based on optical fibre sensing has been demonstrated. An optical fibre coated with an eleven-layer PAH/SiO2 = 0.96) when 11 bilayers of PAH/SiO2 NPs coated on the tip of fibre was used which was higher than that of 7  and 3 bilayers  of PAH/SiO2 nanoparticles. Measurements from 10 volunteers during a cycling test demonstrate the capability of the system to measure the effect of textile properties on humidity, with polyester providing better moisture wicking properties than cotton. The small size and flexibility of the sensors allow them to be easily integrated within garments with negligible effect on the moisture wicking properties and has the potential to be used as a tool for clothing developers designing moisture managing products. The response of the sensing system to RH concentration was linear with a sensitivity of 3.02 mV/% (R


Astrocytes have emerged as crucial regulators of neuronal network activity, synapse formation, and underlying behavioral and cognitive processes. Despite some pathways have been identified, the communication between astrocytes and neurons remains to be completely elucidated. Unraveling this communication is crucial to design potential treatments for neurological disorders like temporal lobe epilepsy (TLE). The BDNF and TrkB molecules have emerged as very promising therapeutic targets. However, their modulation can be accompanied by several off-target effects such as excitotoxicity in case of uncontrolled upregulation or dementia, amnesia, and other memory disorders in case of downregulation. Here, we show that BDNF and TrkB from astrocytes modulate neuronal dysfunction in TLE models. First, conditional overexpression of BDNF from astrocytes worsened the phenotype in the lithium-pilocarpine mouse model. Our evidences pointed out to the astrocytic pro-BDNF isoform as a major player of this altered phenotype. Conversely, specific genetic deletion of BDNF in astrocytes prevented the increase in the number of firing neurons and the global firing rate in an in vitro model of TLE. Regarding to the TrkB, we generated mice with a genetic deletion of TrkB specifically in hippocampal neurons or astrocytes. Interestingly, both lines displayed neuroprotection in the lithium-pilocarpine model but only the mice with genetic deletion of TrkB in astrocytes showed significantly preserved spatial learning skills. These data identify the astrocytic BDNF and TrkB molecules as promising therapeutic targets for the treatment of TLE. Activated astrocytes provide both excitatory and inhibitory effects on neighboring neurons2. Thus, astrocytes can modulate neuronal activity and, in turn, neurons exert functional changes in astrocytes upon neural activity such as modifications in gene expression, gliotransmitter release and intracellular calcium signals6. However, mechanisms underlying astrocyte–neuron reciprocal communication remain poorly understood.Correct function of neuronal networks depends on an appropriate modulation by astrocytes7. This expression pattern suggests that the BDNF–TrkB pathway could be a core system modulating astrocyte–neuron reciprocal communication. The neurotrophin BDNF is a key player in learning and memory processes, synaptic plasticity phenomena, and neuronal survival9 as well as TrkB, its main receptor11. However, BDNF and TrkB molecules have often opposed biological effects explained by the presence of the different TrkB isoforms and the antagonistic biological activity of mature (mBDNF) and precursor (pro-BDNF) forms of BDNF12. As an example, pro-BDNF can activate p75NTR to induce neurotoxicity whereas mBDNF can activate TrkB to induce neuroplasticity12. On the other hand, the truncated isoform of TrkB receptor (TrkB.T1) disrupts/counteracts the full-length (TrkB.FL) active receptor function14 by promoting the formation of non-functional heterodimers15. In contrast to the TrkB.FL-dependent signaling, TrkB.T1-mediated signaling has been suggested to mediate neurodegenerative processes in excitotoxic contexts16. Thus, excess of (pro)BDNF or TrkB.T1 protein levels as well as aberrant interaction between TrkB and p75NTR receptors may lead to neuronal dysfunction or death via induction of excitotoxicity-related molecular pathways17.Recent literature has shown that BDNF and TrkB are expressed in both neurons and astrocytes18. In particular, the increase in TrkB.T1 protein levels could be one of the underlying molecular mechanisms of neuronal death in TLE models19. However, whether astrocytes are regulating synaptic excitability or activation of neuronal populations in TLE-associated neurodegeneration via the BDNF and TrkB molecules remains elusive.A detrimental role of TrkB isoforms has been observed in temporal lobe epilepsy (TLE) modelsIn the present work we show that BDNF overexpression in astrocytes leads to enhanced excitability and neuronal cell death. Furthermore, we show that BDNF from astrocytes is necessary to increase the number of firing neurons in an in vitro model of TLE. In a second subset of results exploring the role of the astrocytic TrkB receptor, we show that a knockdown of total TrkB in astrocytes is beneficial in TLE. Concretely, we show that TrkB deletion in hippocampal astrocytes is neuroprotective in TLE models and preserves with higher rates hippocampal-related cognitive functions when compared to the genetic deletion of TrkB in neurons.23, we aimed to study the role of the neurotrophin produced by astrocytes in a TLE model by using wild-type (WT) mice and the pGFAP-BDNF transgenic mice as a gain-of-BDNF-function approach. In these mice, BDNF is overexpressed only under pathological conditions21. To do so, first we subjected pGFAP-BDNF mice and their WT controls to the lithium-pilocarpine model  increased significantly in field excitatory postsynaptic potentials (fEPSP) slopes with the increase in stimulus intensities  = 40.916; p < 0.001). Slopes of fEPSPs evoked in pGFAP-BDNF mice were significantly larger than those presented by WT animals for higher stimulus intensities  = 4.023; p ≤ 0.05) , we recorded input/output curves and paired-pulse facilitation at the CA3–CA1 synapse in the two groups of mice in vivo Fig. . The two05) Fig. . Altoget25. The two groups of mice presented a paired-pulse facilitation at short (20 and 40 ms) inter-pulse intervals  = 19.025; p < 0.001). Nevertheless, the pGFAP-BDNF group presented a significantly larger paired-pulse facilitation at the interval of 40 ms   for both groups of mice  of kainate Fig. . Both WTice Fig. . The preice Fig.  reduced ice Fig. . Overall23. To functionally explore the influence of astrocytic BDNF over the neuronal population response in an epileptic context we used a loss- and a gain-of-BDNF-function approach in vitro. We evaluated the activity of WT hippocampal neurons co-cultured with (i) BDNF−/− or BDNF+/+ astrocytes and (ii) WT or pGFAP-BDNF astrocytes upon epileptic induction with 4-aminopyrimidine (4-AP)26. Neuronal activity was assessed by in vitro calcium imaging using Fluo4-AM as a fluorescence calcium indicator. Firing activity was inferred from each individual neuron and then averaged and considered as one individual experiment. First, the results showed that 4-AP induced an increase of the firing frequency in both BDNF−/− and BDNF+/+ groups  expressing Cre-recombinase under the control of CAMKII or GFAP promoter, leading to the deletion of TrkB expression in principal neurons or astrocytes, respectively. We performed bilateral hippocampal injections of AAV-CaMKII-GFP, AAV-GFAP-GFP, AAV-CaMKII-Cre-GFP, or AAV-GFAP-Cre-GFP  or from astrocytes in the same hippocampal subregions, we used TrkBGFP Fig. . Next, tare Fig. .Fig. 5Eff/f-GFP-Veh) treated with vehicle. We did not detect significant changes in TrkB.FL expression either in the TrkBf/f-GFP-Pilo or in the TrkBf/f-CaMKII-Cre-Pilo groups   Fig. . These rf/f mice injected with AAV-GFP and treated with vehicle and TrkBf/f mice injected with AAV-GFP or with AAV-GFAP-Cre or with AAV-CaMKII-Cre and treated with pilocarpine . On day 7, we subjected the mice to the open field paradigm. Statistical analysis showed no significant differences between the groups TrkBf/f-GFAP-Cre-Pilo, TrkBf/f-CaMKII-Cre-Pilo, and TrkBf/f-GFP-Veh in spontaneous locomotor activity  was observed in both TrkBf/f-CaMKII-Cre-Pilo and TrkBf/f-GFAP-Cre-Pilo compared to TrkBf/f-GFP-Pilo  may have a key role in the development of SE, and that a reduction of TrkB.T1 (we cannot rule out an effect from undetected TrkB.FL downregulation) expression specifically in astrocytes is neuroprotective and rescues the performance in the NOL task. This is important since TrkB manipulation can alter synaptic plasticity and hippocampal-dependent learning47.TrkB receptor and its truncated isoform TrkB.T1 are expressed in astrocytes and neurons and could mediate the regulation of neuronal hyperactivation in the first stages of TLE48. Compared to our results, this differential effect can be explained by the different temporal approach of the BDNF release. Thus, an acute and sustained increase on BDNF levels during the first stages of TLE can induce an aberrant neuronal hyperexcitability and death while a late-onset and chronic treatment with this neurotrophin induces synaptic changes and promotes neuronal survival49.The role of BDNF and TrkB during different phases of TLE is complex. Previous work showed therapeutic effects of long-term BDNF supplementation in the epileptic hippocampus by reducing degenerating neurons50. Furthermore, TrkB.T1 was diminished/normalized in both groups of mice that have TrkB expression genetically disrupted in neurons or in astrocytes, validating the neuroprotective effect mediated by a reduction of TrkB.T1 expression after SE in a cell-specific manner. Upon excitotoxic conditions, a change in the TrkB isoforms occurs, decreasing the levels of TrkB.FL and increased TrkB.T151. The functional impact of TrkB.T1 increase has been controversial51. According to our results, normalization of TrkB.T1 levels might underlie the neuroprotective effect observed upon TrkB expression reduction, supporting the hypothesis of deleterious effect of TrkB.T1 increase in the epileptic context.Importantly, we found here an outstanding increase in the expression of TrkB.T1 as predicted51. Indeed, we observe a decrease in the phosphorylation of PLCγ upon pilocarpine treatment, which is a main affected molecular pathway by which SE-induced TrkB activation promotes its epileptogenic consequences52. Moreover, conditional reduction of TrkB expression in both neurons and astrocytes is able to rescue the decrease of both pPLCγ and pTrkB, probably due to the reduction of TrkB.T1 that hampers the activation of TrkB.FL receptor53. Conversely, pilocarpine treatment did not modify the BDNF-dependent phosphorylation of Akt as previously described51.Therefore, our results reveal for the first time a major participation of astrocytic TrkB in the cell death and cognitive deficits related to TLE models.TrkB-dependent signaling has been shown to be downregulated in excitotoxic models54. We cannot exclude that changes in phospho-Akt, among others, could have taken place during the first hours just after the pilocarpine treatment. Overall, our results point to astrocytic BDNF and TrkB as promising therapeutic targets for the treatment of TLE.Additionally, we have observed some effects probably due to a delayed time point in which we evaluated the mice. First, despite the weak neuronal death observed in mice genetically depleted of TrkB.T1 and TrkB.FL and treated with pilocarpine, we cannot discard that some neuronal death occurred during the first stages after pilocarpine treatment and we missed it out. Second, the presence of degenerating neurons in some hippocampal subregions (CA1 and CA3) but not in others (CA4) suggests differential sensitivity to pilocarpine of neurons from different hippocampal sub-fields. Thus, it is possible that these different degeneration dynamics have been neglected by focusing our experiments only in one time point. Third, although we observed neuroprotection in different hippocampal sub-fields, we did not detect changes in phospho-Akt, a well-known pathway involved in neuronal survival20. For TrkB deletion, TrkBf/f mice were generated in which the NTRK2 exon S was flanked with LoxP sequences55. We used P1–P3 BDNF+/+ and BDNF−/− mice56  to obtain astrocytes in vitro devoid of BDNF. Mouse genotyping for pGFAP-BDNF, TrkBf/f, and BDNF−/− mice was carried out from a tail biopsy as previously described57. The animals were housed with access to food and water ad libitum in a colony room kept at 19–22 °C and 40–60% humidity, under a 12:12 h light/dark cycle. Age of the mice was specified in each figure legend according to the experimental approach requirements. Experimental animals  were used in accordance with the ethical guidelines .For in vivo experiments in 10-week-old adult male mice  we used pGFAP-BDNF mice that express BDNF under the GFAP promoter12 GCs), rAAV5-GFAP-GFP , rAAV5-CaMKII-Cre-GFP , or rAAV5-GFAP-Cre-GFP . All the AAVs were purchased to the Virus Vector Core UNC . We used the following coordinates (millimeters) from bregma  and from skull ; anteroposterior: −2.0; Lateral +/−1.25, and dorsoventral: −1.3 (CA1) and −2.1 (GD). The cannula was left to deliver 1 μl of 1:1 virus in each depth during 2 min and five additional minutes were left to have complete virus diffusion. After 2 h of careful monitoring, mice were returned to their home cage for 3 weeks before starting the lithium-pilocarpine model and subsequent behavioral and biochemical analysis.Following anesthesia with ketamine/xylazine , we performed bilateral hippocampal injections of rAAV5-CaMKII-GFP  was stopped after approximately 120 min with an intraperitoneal injection of valium . Only animals that displayed 120 min of SE survived and showed the following levels of epileptic seizure were selected: mouth and facial movement, tremors, head nodding, and forelimb clonus.Animals were subjected to the lithium-pilocarpine model of TLE. Briefly, mice were treated intraperitoneally with lithium  20–23 h prior to administration of scopolamine, an anti-muscarinic molecule . Thirty minutes after the administration with methyl-scopolamine, animals were treated with pilocarpine . Control animals were injected with saline solution. Male, 8-month-old pGFAP-BDNF mice and their littermate wild-type (WT) controls of the same age and sex were prepared for the in vivo electrophysiological study of hippocampal functions. These experiments were carried out in the animal facilities of the Pablo de Olavide University. Upon their arrival animals were housed with access to food and water ad libitum and kept at 21 °C and 50% humidity, under a 12:12 h light/dark cycle. Experiments were carried out following European Union Council (2010/276:33–79/EU) guidelines and Spanish  regulations for the use of laboratory animals in chronic experiments. Experiments were also approved by the local Ethics Committee of Pablo de Olavide University (document no 06/03/2018/025).21, animals were anesthetized with 1.2% isoflurane  delivered via a mask adapted to mouse head . Then, animals were implanted with a bipolar stimulating electrode at the right Schaffer collateral-commissural pathway of the dorsal hippocampus  and with two recording electrodes at the ipsilateral stratum radiatum underneath the CA1 area . Electrodes were made of 50 μm, Teflon-coated tungsten wire . The final location of the recording electrodes was determined following the field potential depth profile evoked by paired  pulses presented to the stimulating electrode59. Two bare silver wires were affixed to the skull as ground. Electrodes were connected to a 6-pin socket  that was affixed with dental cement to the cranial bone. After surgery, animals were kept in individual cages provided with food and water ad libitum until the end of the experimental sessions.As already described60.To allow a proper recovery of the experimental animals, recording sessions were started 1 week after surgery. For input/output curves Fig. , monosyn61. Intervals between pair of pulses were set at 30 s to avoid unwanted interactions evoked by pre- or postsynaptic mechanisms.For the paired-pulse facilitation at the CA3–CA1 synapse Fig. , we used63. As illustrated in Fig. In order to determine the propensity of WT and pGFAP-BDNF mice to generate convulsive seizures, animals were injected (i.p.) with the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)/kainate receptor agonist kainic acid  dissolved in 0,1 M phosphate-buffered saline (PBS) pH = 7.4 as previously described to increase hippocampal excitability in vivo+/+ and BDNF−/− mouse pups56 , and from P1 to P3 WT and pGFAP-BDNF mouse pups20 by hippocampal dissections. Extracted tissue was dissociated and placed in 25 cm2 flasks in an MEM 1Px conditioned media NM-15  with l-glutamine and Earle’s salts (Gibco-BRL) and placed in an incubator at 37 °C with 5% CO2. A tail biopsy was obtained from each pup for genotyping. After two passages cultures were purified by agitating in a shaker during 10 min at 400 r.p.m. Medium with undesired floating cells was replaced and flasks were placed in an incubator for 2 h at 37 °C. Next, flasks were agitated again for 16–18 h at 250 r.p.m. Finally, medium with floating cells was replaced with new medium. Once astrocytes reached confluence, they were seeded in 24-well plaques and allowed to reach confluence. Then, one day before the addition of hippocampal neurons, astrocyte cultures were pre-incubated with neurobasal medium  containing 1 ml per 50 ml of B27 supplement (Gibco-BRL) and 500 μl of GlutaMAX (100×) (Gibco-BRL). Hippocampal neurons were prepared from E18 B6CBA mouse embryos . The neuronal cell suspension was low density seeded in the 24-well plaques already containing astrocyte monolayer .Primary astrocyte cultures were obtained from P1 to P3 BDNF2, 2 mM; MgCl2, 1 mM. The recording chamber was mounted on an Olympus IX70 inverted microscope equipped with a Hamamatsu Orca Flash 4.0 V2  camera and Dual OptoLED power supply (Cairn Research Ltd) as a source of light. Fluorescence images were acquired at room temperature (RT) with a ×10 objective (20 frames/s). Neurons were recorded during 10 min for stabilization, afterward for induction of epileptiform activity, 100 μM 4-aminopirimidine or vehicle was added to the EM. After 5 min allowing the diffusion of the drug, activity was recorded during additional 10 min.Calcium fluorescence recordings were carried out at 15 DIV using cell-permeant calcium sensitive dye Fluo4-Acetoxymethyl ester (Fluo4-AM) . Cultures were incubated for 20 min at 37 °C in their own Neurobasal medium in the presence of 1 µM Fluo4. After incubation, cultures were placed in a 35 mm diameter glass bottom chamber  for recording. Recordings were carried out in pH-stable (7.4) external medium (EM). EM consisted of: HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid), 10 mM; NaCl, 128 mM; KCl, 4 mM; glucose, 10 mM; sucrose, 45 mM; CaCl64, a custom-made software package developed in Matlab (MathWorks). Recordings were first time-averaged across the whole recording to obtain a clear picture of the cell bodies. Cells were automatically detected as regions of interest (ROIs) using the time-averaged image. Traces were acquired for each ROI by spatially averaging between its pixels across the whole recording. Each trace was smoothed, and its baseline corrected. To estimate the baseline, a reference point was taken for each 50 s block, and its position within the block determined by the value closest to the 10% lower fluorescence percentile within that block. A smoothing spline was then fitted using this point set. This baseline was subtracted from the original trace and finally normalized to 100 × (F − F0)/F0 relative units.Analysis of calcium imaging recordings was performed with NETCALUsing a supervised machine learning approach, neuronal activity traces were selected. First, traces were visually examined and a subset belonging to neuronal activity class was manually selected. Then the classifier was trained with this subset using adaptive boosting (AdaBoost), machine learning meta-algorithm. The resulting classification was visually inspected and refined by changing the training set as required.65. For the underlying calcium model, a single decaying exponential with non-saturating dynamics with amplitude 1% ΔF0/F0 and decay 3 s was used on all experiments. Active neurons were considered when at least one spike was detected during the recording.Spikes were inferred using a modified Peeling method2 pellets, and stored at −80 °C until use. Briefly, the tissue was lysed by sonication in 150 ml of lysis buffer . After lysis, samples were centrifuged at 12,000 r.p.m. for 15 min. Supernatant proteins (15 mg) from total brain regions extracts were loaded in polyacrylamide gels (SDS–PAGE) at different polyacrylamide concentrations and transferred to nitrocellulose membranes  during 1 h. Membranes were blocked in TBS-T solution  plus 5% non-fat dry milk and 5% bovine serum albumin. Membranes were probed with the following antibodies: anti-BDNF rabbit 1:1000 , anti-GFAP rabbit 1:1000 , anti-TrkB mouse 1:1000 , anti-PLC1γ rabbit 1:1000 , anti-pPLC1γ (Tyr783) rabbit 1:1000 , anti-Akt rabbit 1:2000 , anti-pAkt (Thr308) rabbit 1:1000 , anti-pTrkB (Tyr816) rabbit 1:1000 , and anti-iNOS rabbit 1:1000 . All membranes were incubated with the primary antibodies overnight at 4 °C by shaking in PBS with 0.02% sodium azide. After washed with TBS-T, membranes were incubated with anti-rabbit or anti-mouse horseradish peroxidase-conjugated secondary antibodies . Secondary antibody binding was detected by the enhanced chemiluminescence substrate kit . For loading control a mouse monoclonal antibody for α-tubulin was used . ImageJ software was used to quantify the different densitometry immunoreactive bands relative to the intensity of the α-tubulin in the same membranes. Data are expressed as the mean ± SEM of band density.Animals were euthanized by cervical dislocation. The two hippocampi were dissected out, frozen using COMice were euthanized by cervical dislocation. Left hemispheres were removed and fixed for 72 h in 4% paraformaldehyde (PFA) in PBS. Forty-micrometer coronal sections were obtained using a Leica vibratome (Leica VT1000S). Next, free floating sections were washed three times in PBS, treated with NHCl for 30 min, and washed again three times with PBS. Floating sections were permeabilized and blocked with PBS containing 3% Triton X-100, 0.02% Azide, 2% BSA, and 3% NGS (Ab buffer) for 1 h at RT. After three washes in PBS, brain slices were incubated overnight at 4 °C with FITC-conjugated GFP primary antibody  for signal enhancement. Sections were washed three times and incubated for 2 h at RT with fluorescent secondary antibody Alexa Fluor 488 goat anti-mouse . Sections were analyzed using a two-photon confocal microscope (Leica SP5).To assess degenerating neurons in the hippocampus, mice were sacrificed 10 days after the administration of pilocarpine or vehicle. Left hemispheres were removed and kept in PFA during 3 days with constant shaking. At this point, PFA was replaced for PBS until the brains were cut. Forty-micrometer coronal sections were obtained using the Leica vibratome (Leica VT1000S). Brain sections were mounted with distilled water onto SuperFrost slides (Thermo Scientific™ SuperFrost™ Microscope Slides) and dried at RT. The tissue was fully dry within 30 min at which time it was immersed in 100% ethyl alcohol for 3 min followed by a 1 min change in 70% alcohol and a 1 min change in distilled water. The slides were then transferred to a solution of 0.06% potassium permanganate for 15 min and were gently shaken on a rotating platform. The slides were rinsed for 1 min in distilled water and were then transferred to the Fluoro-Jade staining solution where they are gently agitated for 30 min. A 0.01% stock solution of the dye was prepared by dissolving 10 mg Fluoro-Jade in 100 ml of distilled water. The 0.001% working solution of Fluoro-Jade was prepared by adding 10 ml of the stock Fluoro-Jade solution to 90 ml of 0.1% acetic acid in distilled water. After staining, the sections were rinsed with three 1 min changes of distilled water. Excess water was drained off, and the slides were rapidly air dried. When dry, the slides were immersed in xylene and then mounted with Mowiol mounting media.Sections were analyzed using an Olympus BX60 epifluorescent microscope equipped with an Orca-ER cooled CDD camera  with the Hokawo (Hamamatsu) image software acquisition. Three hippocampal sections were analyzed per animal and for each section five images were taken using the ×20 objective. To quantify the degenerating cells, the mean area of CA1, CA3, and CA4 was measured for each section and the number of Fluoro-Jade C (FJC)-positive cells inside this area was counted using FIJI software . The mean value of all animals from each group was obtained and represent as % related to the control group and as % related to the CA1 of the control group.71. First, materials for the SHIRPA evaluation consisted of a transparent Perspex viewing jar, a clean cage, a wire grid cage lid, and a stopwatch. During the procedure, each mouse was removed from the home cage, evaluated individually in the viewing jar, and then placed into the clean cage for further evaluation. Finally, animals were placed on the grid cage and last items were evaluated. The viewing jar and the testing cage were cleaned with 70° ethanol between animals to avoid the possibility of olfactory cues affecting behavior. The data from individual components of the modified SHIRPA were pulled to provide a general SHIRPA index as previously described72. For further information about the SHIRPA procedure, more detailed information is provided in the Mouse Phenome Database at the Jackson Laboratory’s website: https://phenome.jax.org/projects/Jaxpheno7/protocol#SHIRPA.To provide detailed mid-term general phenotype assessment 7–9 days after the pilocarpine treatment, mice were tested using the phenotype assessment protocol called SHIRPA, the OF, and the NOL test, all these tests have been used to detect mid-term behavioral alterations such as general neurological alterations, hyperlocomotion activity, and memory impairments induced by pilocarpineTo check spontaneous locomotor activity, anxiety-like parameters, and navigation we used the OF. Briefly, the apparatus consisted of a white square arena measuring 40 × 40 × 40 cm in length, width, and height, respectively. Dim light intensity was 60 lux throughout the arena. Animals were placed on the arena center and allowed to explore freely for 30 min. Spontaneous activity was measured. At the end of each trial, any defecation was removed, and the apparatus was wiped with 30% ethanol. Animals were tracked and recorded with SMART junior software .The NOL memory task evaluates spatial memory and is based on the ability of mice to recognize when a familiar object has been relocated. Exploration took place in an open-top arena with quadrangular form (45 × 45 cm). The light intensity was 40 lux throughout the arena. Mice were first habituated to the arena in the absence of objects . Some distal cues were placed throughout the procedure. On the third day during the acquisition phase mice were allowed to explore two duplicate objects (A1 and A2), which were placed close to the far corners of the arena for 10 min. After a delay of 24 h, one object was placed in the corner diagonally opposite. Thus, both objects in the phase were equally familiar, but one was in a new location. The position of the new object was counterbalanced between mice. Animals were tracked and recorded with SMART Junior software.F test to compare variances. In experiments with normal distribution statistical analysis were performed using the unpaired two-sided Student’s t-test (95% confidence), one-way ANOVA with the Tukey’s as post hoc tests, two-way ANOVA with the Bonferroni’s post hoc test as appropriate and indicated in the figure legends. Values of p < 0.05 were considered as statistically significant. Grubbs’ test was performed to determine the significant outlier values. All experiments in this study were blinded and randomized by blocks of animals. All mice bred for the experiments were used for preplanned experiments and randomized to experimental groups. Data were collected, processed, and analyzed randomly. The experimental design and handling of mice were identical across experiments. Littermates were used as controls with multiple litters (3–5) examined per experiments.Sample sizes were determined by using the power analysis method: 0.05 alpha value, 1 estimated sigma value, and 75% of power detection. All data are expressed as mean ± SEM. Normal distribution was tested with d’Agostino and Pearson omnibus, Shapiro–Wilk, and Kolmogorov–Smirnov normality tests. If at least one of them was passed, statistical analysis was performed using parametric statistical analysis. Otherwise non-parametric Mann–Whitney or Kruskal–Wallis or Dunn’s tests were used. Before pairs of comparisons we performed the


Idiopathic pulmonary fibrosis (IPF) is a chronic progressive lung disease. Several risk factors such as smoking, air pollution, inhaled toxins, high body mass index and infectious agents are involved in the pathogenesis of IPF. In the present study, this meta-analysis study investigates the prevalence of viral and bacterial infections in the IPF patients and any possible association between these infections with pathogenesis of IPF.The authors carried out this systematic literature review from different reliable databases such as PubMed, ISI Web of Science, Scopus and Google Scholar to December 2020.Keywords used were the following “Idiopathic pulmonary fibrosis”, “Infection”, “Bacterial Infection” and “Viral Infection”, alone or combined together with the Boolean operators "OR”, “AND” and “NOT” in the Title/Abstract/Keywords field. Pooled proportion and its 95% CI were used to assess the prevalence of viral and bacterial infections in the IPF patients.In this systematic review and meta-analyses, 32 studies were selected based on the exclusion/inclusion criteria. Geographical distribution of included studies was: eight studies in American people, 8; in European people, 15 in Asians, and one in Africans. The pooled prevalence for viral and bacterial infections w ere 53.72% (95% CI 38.1–69.1%) and 31.21% (95% CI 19.9–43.7%), respectively. The highest and lowest prevalence of viral infections was HSV (77.7% 95% CI 38.48–99.32%), EBV  and Influenza A , respectively. Whereas the highest and lowest prevalence in bacterial infections were related to Streptococcus sp.  and Raoultella , respectively.The results of this review were confirmed that the presence of viral and bacterial infections are the risk factors in the pathogenesis of IPF. In further analyses, which have never been shown in the previous studies, we revealed the geographic variations in the association strengths and emphasized other methodological parameters . Also, our study supports the hypothesis that respiratory infection could play a key role in the pathogenesis of IP. IPF causes progressive scar tissue which gets worse over time resulting in acute dyspnea  in IPF patients.Conducting valid laboratory techniques such as: molecular technique, culture, and serology.Selecting the proper sampling method including: NPS, OPS, Sputum, Serum, Blood, BAL and Lung Biopsy.The inclusion criteria for eligible publications were defined as: all research thatProviding incomplete data or failed presented data clearly.Animal models-based research.Had other infectious agents.Overlapping subjects, time, and place of sample collection.The exclusion criteria: all research thatData extraction was conducted by two authors separately and independently based on author’s name, year of publication, total sample size, number of bacterial and viral infections patients, country, types of bacteria, types of viruses, types of samples and detection methods. Individual data from each included study were used in this meta-analysis. Extracted data were compared and rechecked by the first and corresponding authors. The methodological quality of the included studies was evaluated using the STROBE checklist. A maximum quality evaluation score of 32 was considered and articles with scores below 18 were excluded from this study .Pooled proportion and its 95% CI were used to assess the prevalence of viral and bacterial infections in the IPF patients. Generalized linear mixed and random intercept logistic regression models were used for pooling prevalence . The hetThe process of research selection shown in Fig. Based on the results of the STROBE checklist, highest and lowest score were related to Dworniczak et al. score = 18) and Keyvani et al. (score = 31), respectively. The mean score of STROBE tool for all of included studies was 25.8 .  according to a random effects meta-analysis. The Wald test showed a significant heterogeneity of prevalence between the studies  , EBV  and Influenza A , respectively  Fig. . In mostIPF is a fatal progressive lung disease that there is no effective cure for this except lung transplant for end-stage IPF patients . MoreoveThus far, no systematic review and meta-analysis study has been investigated in the prevalence and the role of viral and bacterial infections in IPF except an investigation by Sheng et al. They suggested viral infection as a risk factor , however not statistically significant relationship was detected between viral infection and exacerbation of IPF . They also demonstrated that some viruses such as CMV, Epstein-Barr virus (EBV) and human herpesvirus 7, and 8  were associated with IPF as the risk factors, while HHV-6 was not associated. Therefore, their results indicated that viral infections may involve in IPF pathogenesis . In our The viral infection  may be involved in increasing of inflammation (chronic), resulting in the pathogenesis of IPF , 24, 29.Streptococcus (30%) followed by Veillonella (10.6%) and Prevotella (10.9%) [Pseudomonas, Haemophilus and Streptococcus [Streptococcus sp.  and Raoultella , respectively. High case fatality rate related to bacterial respiratory tract infection in IPF, indicating that bacteria are involved in driving IPF disease progression. Recently, studies using culture-independent techniques have demonstrated that increased bacterial DNA burden in IPF patients is associated with an enhanced risk of earlier mortality in IPF [Although, numerous attempts have conducted on the role of viruses in the IPF pathogenesis, there are a few studies investigating the role of bacteria in this disease. In a recent study, it was demonstrated that 7.5% of IPF patients (BAL sample) were found to be positive in bacterial culture, while none of the controls had bacterial infection. The most common bacterial genus were nella 10.% and Pretococcus . In our nella 10.% and Prey in IPF , 35. TheCytokine patterns in patients with IPF may shed light on the predominant cell types pivotal to various stages of the disease. Overexpression of Th2 Cytokines including IL-4, IL-5, and IL-13 in cellular cultures from patients with IPF has been previously reported . IL-1α aAll researches that reported the viral and bacterial infection in IPF patients were included in this meta-analysis. The sample size in some researches was small. Furthermore, the viral and bacterial infection rates were variable due to Variety of geographical locations, viral/bacterial detection techniques and the sites of biological samples or type of samples. Different methods led to alterations in sensitivity and specificity. Given these challenges, larger-scale samples are needed in the future to draw conclusions about causal relationship between IPF and viral-bacterial infections.Our study had several limitations; first, the small sample size, relative wide confidence intervals and study were conducted in a single center. Second, the pathogen types were specific to the study area. Thus, our results are probably not applicable to other patient populations. The association between viral infection and acute exacerbation of IPF requires further investigation.The current study provides the overall viral and bacterial infection prevalence in IPF patients and information about circulating types of viruses and bacterial worldwide. The presence of viral and bacterial infections is a risk factor in the pathogenesis of IPF. We revealed the geographic variations in the association strengths and emphasized other methodological parameters  in further analyses that have never been shown in the previous studies. Also, our study supports the hypothesis that respiratory infection could play a key role in the pathogenesis of IPF.


In recent years, the characteristics of the graphene/crystalline silicon junction have been frequently discussed in the literature, but study of the graphene/polycrystalline silicon junction and its potential applications is hardly found. The present work reports the observation of the electrical and optoelectronic characteristics of a graphene/polycrystalline silicon junction and explores one possible usage of the junction. The current–voltage curve of the junction was measured to show the typical exponential behavior that can be seen in a forward biased diode, and the photovoltage of the junction showed a logarithmic dependence on light intensity. A new phototransistor named the “photodiode–oxide–semiconductor field effect transistor (PDOSFET)” was further proposed and verified in this work. In the PDOSFET, a graphene/polycrystalline silicon photodiode was directly merged on top of the gate oxide of a conventional metal–oxide–semiconductor field effect transistor (MOSFET). The magnitude of the channel current of this phototransistor showed a logarithmic dependence on the illumination level. It is shown in this work that the PDOSFET facilitates a better pixel design in a complementary metal–oxide–semiconductor (CMOS) image sensor, especially beneficial for high dynamic range (HDR) image detection. The unique structural, electronic, and optical properties of graphene have made this two-dimensional material an attractive subject of research in recent years. While the high carrier mobility in graphene opened the door to its applications in high-speed electronics ,2,3,4, tInterestingly, while there have been a number of studies studying graphene/c-Si junctions and their application to photodetection ,29,30,314 and 105 cm−1 [2. Silver paste was respectively applied to the surface of exposed poly-Si and the surface of graphene to form the two electrical terminals of the graphene/n-type poly-Si junction. The reason for using silver paste as the contact material was that it could be easily applied to quickly finish sample preparation and it had been tested to form ohmic contacts with graphene and with n-type c-Si. It was speculated that the paste might still form ohmic contacts with n-type poly-Si. Before a graphene/poly-Si junction is used for applications, it is essential to have a look at its general electrical and optoelectronic characteristics. For this purpose, samples of graphene/n-type poly-Si junction were fabricated. A 300 nm-thick phosphorus-doped poly-Si film was deposited on an n-type Si wafer by using low pressure chemical vapor deposition (LPCVD) at a temperature of 620 °C. Because the optical absorption coefficient of poly-Si in the visible light band is between 10105 cm−1 , the thi105 cm−1 ,36. The RSH) of the graphene film was measured by using a four-point probe. Values between 250 Ω/square and 300 Ω/square were obtained for all the samples. The sheet resistance  at room temperature with the terminal of the poly-Si set at ground potential. I–V curve under the illumination of a halogen lamp. The optical power of the lamp was unknown. It can be seen from I–V curves do not show the simple exponential behavior of a single rectifying junction. Instead, they show the typical behavior of a metal–semiconductor–metal (MSM) structure with two asymmetric rectifying junctions [I–V curves and it is no longer straightforward to extract the exact values of junction parameters , we can still see that the dark current flowing through the single-layer graphene/n-type poly-Si junction increases exponentially with increasing forward bias voltage. The large ideality factor, n, of this disturbed forward bias characteristic was found by curve fitting to be about 10. The exponential dark I–V curve under forward bias implies that we should be able to see a logarithmic dependence on light intensity from the open-circuit photovoltage of the junction, as analyzed below.To see the graphene/n-type poly-Si junction behave like an ohmic junction or a Schottky junction, the dark unctions ,38. The I–V characteristic of a junction can be expressed asn is the ideality factor of the junction, sI is the dark reverse saturation current of the junction, and phI) of the PD is directly proportional to the incident light intensity. If at t = 0, a light starts to illuminate the junction under the open-circuit condition, the photocurrent does not flow out. It charges the junction capacitance (DC) and internally forward biases the junction at the same time. The dynamics can be described byThe general exponential dark phV), should follow the next equation:phI is the photocurrent, and t is the exposure time. The logarithmic response of the photovoltage to light intensity (via phI) is advantageous because it mimics human eyes’ response to brightness. Utilizing phV as the output signal allows one to detect a wide dynamic range of light intensity. Unlike the photocurrent that may easily saturate the subsequent reading circuit at high illuminance, the photovoltage allows the circuit to function properly because the signal is logarithmically compressed at high illuminance but still linear at low illuminance. When the incident light is weak or the exposure time is short, Equation (3) reduces tophI, sI, and DC are all proportional to the junction area, which means that it is not necessary to enlarge the device size of the PD in order to obtain a significant magnitude of photovoltage.Solving Equations (1) and (2) by the separation of the variables, with the zero initial condition I–V curve of the fabricated graphene/n-type poly-Si junction sample at room temperature shows an exponential characteristic under forward bias, it can be expected that if this junction is used as a PD, the photovoltage of the PD should exhibit a logarithmic dependence on the incident light intensity. Even though there exists an additional silver paste/poly-Si junction at the other side of the poly-Si, the photo-generated holes in the poly-Si can still flow to the graphene and build up the photovoltage. Since the measured dark The logarithmic behavior of the photovoltage of a PD makes this variable particularly useful for being adopted in CMOS image sensors as a signal to detect high dynamic range (HDR) images. Furthermore, the graphene/n-type poly-Si junction PD can bring even more benefit to this application because it can be implemented right on top of the gate oxide of a MOSFET in the pixel of a CMOS image sensor. GV) to a high value (VDD). Then, the Reset transistor is turned off and GV is reduced by the discharging mechanism due to the photocurrent phI generated from the PD. The amount of the voltage reduction (ΔV) at node G is a linear function of phI as shown in Equation (6):t is a specified discharging period, TC is the total capacitance at node G, DC is the capacitance of the PD, GC is the capacitance looking into the gate of the source follower (SF) transistor, and pC is the parasitic capacitance due to interconnect. A large fill factor of the PD in the pixel is preferred so that phI can be maximized and TC can be less influenced by GC and pC. After the discharging period,GV signal is output through the source follower to the column bus, and ΔV is used to represent the average light intensity during the discharging period. This linear operation principle has limitations: Firstly, for high light intensity, phI and ΔV can easily become too large and GV may be reduced too much to make the SF transistor functional. This saturation limits the detectable range of input light intensity. Secondly, for high resolution image sensors, there exists a tradeoff between the pixel size and the fill factor of the PD in a pixel. This limits the values of phI and DC, and the influence from GC and pC becomes obvious. Modifying the 3T pixel structure can resolve these limitations.Conventionally, the PD in the pixel is a monolithic P–N junction diode located beside the transistors. To operate the pixel, the Reset transistor is first turned on to set the voltage at node G (VREF) that makes the SF transistor always functional. In this way, the GV is first reset to VREF and then becomes the sum of VREF and the photovoltage of the PD after some exposure time t. The photovoltage of the PD can be expressed as Equation (3) except that DC should now be replaced by TC. Therefore, as explained in Equations (4) and (5), the GV in the modified pixel structure now behaves linearly at low light intensity but changes logarithmically at high light intensity. With the proper setting of VREF, the GV value does not exceed VDD and can always make the SF transistor functional. This natural compression of the signal allows the dynamic range of incident light intensity to be extremely wide, which makes the single-shot detection of high-contrast images possible. There is no need to take multiple shots of an HDR image at different exposure levels and then blend these images together for a composite image. Furthermore, if the original P–N junction PD is replaced with a graphene/n-type poly-Si junction PD that is directly fabricated on top of the gate oxide of the SF transistor, the parasitic capacitance pC can be eliminated and the tradeoff between pixel size and fill factor can be removed. That is, one can combine the PD and the SF transistor into a new integrated device, namely, the PD–oxide–semiconductor field effect transistor (PDOSFET), to maximize pixel performance. In this way, since the PD is directly stacked on the gate of the SF transistor, metallic interconnect is not needed and pC is completely eliminated. In addition, because the stacking makes the area of the PD the same as the gate area of the SF transistor, the photovoltage of the PD is independent of the area and there is no more area-competing issue between the PD and the MOSFET. Poly-Si/graphene PD offers unique advantages for this integration. The n-type poly-Si gate is an essential element in most CMOS technologies. All one needs to do is to apply a graphene film to the gate area to form the PD. Additionally, the graphene film has good thermal stability and can withstand the thermal cycles in subsequent fabrication processes. Therefore, one can apply it either before or after the poly-Si deposition process, which allows flexibility in designing the polarity of the PD. If graphene is placed above poly-Si, its transparency allows light to pass through and reach the poly-Si for optical absorption. Metal/poly-Si Schottky PD cannot provide these advantages.To verify the PDOSFET concept, a test device as schematically illustrated in 2O2. After rinsing in de-ionized (DI) water, the graphene was placed onto the Si wafer with gate oxide already grown on it, and the PC layer was subsequently removed with chloroform. The graphene was then patterned by lithography and RIE according to the designed gate pattern, followed by normal poly-Si gate deposition, lithography, and self-aligned CMOS processes in which the source and drain doping was implemented by using arsenic (As) ion implantation with an energy of 30 KeV and a dose of dI-gV and dI-dV characteristics of the fabricated PDOSFET in the dark were measured by using an Agilent 4156a semiconductor parameter analyzer. dI–gV curve of the PDOSFET under 3.3 V drain-to-source voltage (dsV). Normal turn-on behavior was observed. The threshold voltage for the channel to turn on is between 1 V and 1.5 V. By using the ATLAS device simulator from Silvaco, the threshold voltage of a MOSFET, the same as that for the PDOSFET shown in gV) so that the control of the surface potential at the channel surface by Vg becomes less effective. dI–dV characteristics of the PDOSFET under various gate bias voltages. Normal linear and saturation behaviors can be clearly recognized. The channel length of the fabricated PDOSFET is quite long; therefore, the short channel effect is hardly seen in The resultant PDOSFET looks just like a normal n-channel MOSFET (NMOSFET) except that a graphene layer is inserted between the n-type poly-Si gate and the gate oxide. That is, a PD is embedded right in the gate structure with minimal process modification. The device should be able to exhibit the normal dark electrical characteristics of an NMOSFET. To verify this, the outV) shows a logarithmic dependence on illuminance. This indicates that both the graphene/n-type poly-Si junction PD and the FET integrated in the PDOSFET functioned well. Under low illuminance, Vout changes linearly with light intensity to provide good resolution. At high illuminance, outV is compressed to prevent saturation. The feasibility of using a single PDOSFET in a pixel to replace the P–N junction PD and the SF transistor is thus verified. It should be mentioned that the modification from the conventional 3T pixel structure to the new 3T pixel structure with the PDOSFET is very slight and that the responsivity of the graphene/poly-Si PD is mainly determined by poly-Si, not by graphene. Therefore, except for the optical input dynamic range, most other performance parameters such as the quantum efficiency, conversion gain, noise, and image lag of the new pixel should be similar to those of the conventional pixel.When the PDOSFET is illuminated with light, the photovoltage developed at the PD should be able to effectively increase the gate voltage of the FET and thus increase the channel current. Therefore, when the PDOSFET is connected in a source follower configuration, the output voltage of the source follower should faithfully reflect the logarithmic behavior of the photovoltage of the PD. DSV = 5 V. Therefore, the observed logarithmic dependence of outV  on illuminance is certainly not due to (at least not dominated by) the optical absorption in the c-Si substrate. Instead, the graphene/n-type poly-Si PD on top of the gate dominates the optoelectronic behavior of the PDOSFET source follower.Although the thickness of the poly-Si gate was designed to be 300 nm to absorb most of the visible light, it cannot be ruled out that some long wavelength light may still travel through the gate and reach the c-Si region under the gate oxide. These photons may still generate electron–hole pairs and contribute to the increase in the drain current. However, if this influence exists and dominates, the magnitude of the drain current increase should be linearly proportional to the increasing illuminance. Besides, the photo-generated drain current of the MOSFET control device (without PD at the gate) under 49,000 Lux illumination was measured to be only 0.1 μA even at In addition, it was mentioned above that the source and drain areas of the PDOSFET were covered by metal in order to prevent the source and drain junctions from detecting light and contributing extra photocurrent. The effectiveness of this arrangement was investigated by measuring the dark and light drain currents when the gate voltage was set low to disable the channel. No change in the terminal current magnitude was observed with and without illumination. This confirms that the metal coverage on the source and drain regions effectively blocked the incident light.outV) was observed. For the fabricated large, long-channel PDOSFET, both the rise time and the fall time of outV were as short as 22 μs when the loading resistance was 100 kΩ, as shown in For most applications, it is desirable for the intrinsic operation speed of the phototransistor to be fast. Therefore, the transient response of the PDOSFET source follower was also investigated in this work. A white light-emitting diode (LED) was switched on/off by a voltage square wave to produce 5000 Lux light pulses onto the PDOSFET. The transient behavior of the source follower output voltage (One process issue about employing the proposed PDOSFET in mass production is the use of graphene in the front-end of standard, commercial CMOS processes. In such mass production processes, it is impossible to deposit the graphene layer by using slow techniques such as the transfer method. The direct wafer-level synthesis/deposition of graphene is needed. Besides, possible carbon contamination of the devices on the chip, due to the gases used in the graphene deposition process, must be avoided. Otherwise, graphene will not be usable in the front end of CMOS processes and it will be impossible to fabricate the PDOSFET. Although the new pixel structure shown in −2 dose to make it n-type. At the ohmic contact area, heavy doping was achieved by an additional ion implantation with 10 KeV of energy and a −2 dose. The area of the PD was designed to be As a remark, one possible way to implement the pixel structure shown in I–V curve of the junction was found to be exponential, and the junction responded to light, with its photovoltage being a logarithmic function of illuminance. A new phototransistor called the PDOSFET, in which the graphene/n-type poly-Si junction PD was directly integrated with an n-channel MOSFET, was proposed, fabricated, and functionally verified. The channel current of the PDOSFET was efficiently modulated by the photovoltage of the PD and thus responded to light intensity logarithmically. The proposed PDOSFET shows great potential for CMOS image sensor applications, especially for detecting HDR images.A graphene/n-type poly-Si junction PD was fabricated and characterized in this work. The dark