Background: Sarcoidosis is a granulomatous disease involving intrathoracic and extrathoracic organs. Genetic and environmental factors, such as exposure to World-Trade Center (WTC) dust after 9/11, may play a role in clinical presentation. Characterization of sarcoidosis in community members with exposure to the WTC dust can provide further insight into the relationship between environmental exposure and sarcoidosis. Methods: Patients with documented sarcoidosis were identified in the WTC Environmental Health Center (EHC), a treatment program for community members. Demographic and clinical data were collected from standardized questionnaires and chart review. Organ involvement was assessed with a standard instrument. Results: Among patients in the WTC EHC, 87 were identified with sarcoidosis after 9/11. Sarcoidosis cases were more likely African-American, local workers, and had more respiratory symptoms, compared with non-sarcoidosis WTC EHC patients. Many (46%) had ≥ Scadding stage 3 on chest imaging, and had reduced lung function measures. Extrathoracic involvement was identified in 33/87 (38%) with a diversity of organs involved. Conclusions: WTC-exposed sarcoidosis in community members is often characterized by severe pulmonary disease and a high rate of diverse extrathoracic involvement. Further analysis is required to characterize the course of disease progression or resolution. Sarcoidosis is a multisystem granulomatous disease of unknown etiology that is currently considered a genetically primed abnormal immune response to an antigenic exposure or trigger . Rather Whereas sarcoidosis can affect nearly all organs and tissues, intrathoracic involvement including hilar and mediastinal lymph nodes and/or lungs is the most common presentation ,9. HowevThe WTC Environmental Health Center (WTC EHC) is a treatment program for self-referred community members, or “survivors,” with medical and mental health conditions secondary to acute exposure to the WTC dust on 9/11 (dust cloud) and/or chronic exposure to the WTC dust and fumes in their homes and/or workplaces over the ensuing days and months . These chttps://www.cdc.gov/wtc/handbook.html#certifications) and signed consent to have their data analyzed. By federal rules, WTC-exposed sarcoidosis cases allowed to enroll in the WTC EHC must have intrathoracic involvement presumed secondary to their relevant WTC exposure. The Institutional Review Board of New York University School of Medicine approved the research database (NCT00404898), and only data from patients who provided informed consent were used for analysis. Patients were included for analysis if they had biopsy proven sarcoidosis or chest imaging with characteristic findings of sarcoidosis defined as bilateral symmetrical mediastinal and/or hilar adenopathy, perilymphatic nodules, or fibrosis with bronchial distortion, at time of diagnosis or initial evaluation and without alternative etiology [Patients were included for review if they were enrolled in the Bellevue Hospital WTC EHC with a “certified” diagnosis as defined by the Centers of Disease Control . Pathology reports were reviewed for all patients with available information to confirm histologic culture-negative, noncaseating granulomas. For those without a biopsy, imaging reports were reviewed to confirm characteristic findings. Information on demographic and clinical characteristics, including WTC and other exposures, were obtained from a standardized questionnaire completed upon entry into the WTC EHC . InformaSarcoidosis cases were staged for pulmonary disease by both CXR and/or CT scan using Scadding staging: stage 0: no adenopathy or infiltrates; stage 1: hilar and mediastinal adenopathy alone; stage 2: adenopathy and pulmonary infiltrates; stage 3: pulmonary infiltrates alone; and stage 4: pulmonary fibrosis . RadiogrThe World Association of Sarcoidosis and Other Granulomatous Diseases (WASOG) organ assessment instrument was used to categorize sarcoidosis involvement of each organ system at time of initial evaluation . A findip-Values < 0.05 were considered statistically significant.Descriptive statistics were used to summarize the study cohort. We used count and percentage for categorical variables and median and IQR  for continuous variables. Univariate analyses were performed to compare the demographic characteristics, clinical characteristics, laboratory values and pulmonary function metrics between sarcoidosis patients and non-sarcoidosis patients and also between sarcoidosis patients who had lung disease at Scadding stage 1–2 and those who had stage 3–4 disease. The comparison tests include n = 11) were excluded from analysis. This resulted in 87 individuals with sarcoidosis available for analysis. Biopsy-proven sarcoidosis was identified in 77, and an imaging diagnosis was obtained for 10. Sarcoidosis diagnosis occurred on average 7 years (SD = 4.5) after 9/11/2001 and 3 years (SD = 4.8) before enrollment in the WTC EHC, with mean time to enrollment being 10 years (SD = 4.4) after 9/11/2001. Among 5849 community members at Bellevue Hospital enrolled between 17 August 2005 and 30 March 2018 with signed consents for analysis, 98 were identified with WTC-related sarcoidosis as per defined federal rules. Patients with a sarcoidosis diagnoses that predated 9/11 (n = 607) were excluded to allow meaningful comparison of pulmonary physiology. For these non-sarcoidosis patients (n = 5144), time to enrollment in the WTC EHC occurred on average 9 years (SD = 3.8) after 9/11/2001.As far as the 5751 non-sarcoidosis community members, patients without lung function values  sarcoidosis patients with available chest imaging had severe lung disease defined as Scadding stage 3 or 4. Patients with more severe radiographic disease had reduced FEV1, FVC and DLCO compared with patients with milder radiographic changes (Lung function measurements including pre and post bronchodilator (bd) spirometry, lung volume and diffusion capacity measures were evaluated in patients with sarcoidosis compared with the non-sarcoidosis patients . Sarcoid changes .n = 54) versus extrathoracic disease, severe lung disease , or extent of extrathoracic organ involvement . Few patients  had elevated ACE levels. Median neutrophil-to-lymphocyte ratio (NLR) was 2.4, compared to a reported mean of 1.65 in an adult, non-geriatric, healthy population [Thirty-three (38%) of the sarcoidosis patients had evidence of extrathoracic involvement: 19 (22%) had two organs involved, 10 (12%) had three organs involved, and 5 (6%) had ≥ four. Diverse organ involvement was identified; however, ocular involvement (15%) was the most common extrathoracic manifestation followed by skin (13%). Fewer had confirmed nervous system (3%) or cardiac (6%) involvement . There wpulation .Electrocardiograms were available for review in 75 individuals; 10 had abnormalities suggestive of potential cardiac sarcoidosis, including left or right bundle branch block, left anterior fascicular block or other interventricular conduction delay. Subsequent transthoracic echocardiogram was performed in 7/10 of these patients. The majority (86%) had normal left ventricular ejection fraction without any associated wall motion abnormalities. A total of 14 patients were referred for advanced cardiac imaging (either cMRI or PET). 6/14 were referred due to abnormal ECG, echocardiogram, and/or continuous ambulatory ECG monitoring; the remaining eight were referred due to concerning cardiac symptoms alone . Cardiac involvement was confirmed in 5/14 patients, one with a supporting myocardial biopsy and two with an unremarkable screening study. Many patients were awaiting advanced cardiac imaging at the time of this publication, including 7 patients with an abnormal EKG and 6 with abnormal continuous ambulatory ECG monitoring. We described the clinical characteristics of a heterogeneous cohort of WTC-exposed community members, or “survivors,” with post-9/11 sarcoidosis. The demographic characteristics of the WTC EHC population with sarcoidosis differed from the FDNY, with many more patients who were female or who identified as African American or Hispanic. These characteristics were more similar to the general population described in ACCESS and the cohort from Medical University of South Carolina (MUSC) ,10,11.By definition, WTC-exposed sarcoidosis cases must have intrathoracic involvement 100%). However, the WTC-exposed survivors with sarcoidosis differed from other sarcoidosis variants—the WTC-exposed FDNY cohort as well as previously reported non-exposed general population(s)—in terms of severity of their intrathoracic disease ,8,10,11.0%. HowevThe frequency of extrathoracic involvement 38%) was slightly less than that reported in ACCESS (50%) % was sli,11. ThisCardiac sarcoidosis remains a challenging diagnosis with current guidelines recommending advance cardiac imaging only in patients with symptoms, abnormal (ECG), or abnormal echocardiogram ,19. HoweThis study has several limitations. Complete analyses of all patients were not possible due to missing data. Many patients referred to the WTC EHC also receive care at outside institutions, including some critical components of sarcoidosis screening for extrathoracic disease. Thus data from other institutions may not have been captured by our study, leading to potential underreporting of extrathoracic organ involvement. Furthermore, although a standardized approach to diagnosis and evaluation was recommended at the WTC EHC, diagnostic studies were varied. Patients shared a common WTC exposure; however, the degree and extent of that exposure, including differences among the WTC dust characteristics, is known to vary, complicating the environmental exposure analysis. Patients had ranging dates of initial sarcoidosis diagnosis. Given the tendency of sarcoidosis organ involvement to increase per year, it is likely that patients in our cohort with more recent dates of diagnosis will continue to develop extrathoracic involvement as time progresses. In addition, longitudinal analysis was confounded by irregular follow-up by many patients, and visit incongruity made it difficult to compare number of organs involved per equivalent time period. Additional analyses are needed to further characterize clinical course. Our data suggest a WTC-exposed sarcoidosis phenotype in community members or “survivors” often characterized by severe pulmonary disease and diverse extrathoracic involvement. These characteristics differ from those described for the FDNY. Similarities to general population studies are likely secondary to comparable gender and race/ethnicity distribution with differences in severity of pulmonary disease and rare organ involvement potentially explained by WTC exposure. Further analysis is required to characterize the course of disease progression or resolution.


Electrolytically tunable graphene “building blocks” for reconfigurable and optically transparent microwave surfaces and absorbers have been designed and fabricated by exploiting Deep Eutectic Solvents (DESs). DESs have been first explored as electrolytic and environmentally friendly media for tuning sheet resistance and Fermi level of graphene together with its microwave response . We consider the tunability of the reconfigurable surfaces in terms of transmittance, absorption and reflectance, respectively, over the X and Ku bands when the gate voltage is varied in the −1.4/+1.4 V range. The numerical simulations and experimental measurements also show the ability of the absorber, in the Salisbury screen configuration, to achieve near perfect absorption with a modulation of about 20%. These results could find applications in several technological fields, ranging from electromagnetic pollution to integrated multi-physical regulation systems, thereby helping the advance of the performance of microwave cloaking systems, stealth windows, frequency selective surfaces, modulators and polarizers. In this framework, one important aspect is related to the ability to manipulate and control reflection, transmission and absorption of microwave radiation in devices that are also optically transparent. In the literature, there are recent examples where attempts are made to achieve microwave absorption in optically transparent structures by means of several configurations based on metamaterials9, metasurfaces10, metallic meshes12, and Salisbury screens13. Recently, the possibility to integrate an optically transparent absorber with an acoustic absorber has also been reported14, leading to a multi-physical regulation system. These devices offer new functionalities, although they share a common limitation: they are “static” and their properties mainly relate to their geometry.The quest for optically transparent microwave devices has increased over the last years. This growing research interest is driven by the opportunity to combine photonic and microwave technologies, thus creating new applications17. Electrolytic gating allows the controlled switching from pristine (high Rs) to doped graphene (low Rs). This opens the possibility (for an optimized configuration) to switch from a microwave transparent window to an absorbing or reflecting one. However, the reported examples of microwave absorbers typically have configurations based on metallic and opaque surfaces. Thus, they are not transparent in the visible range. Moreover, electrolytic gating of graphene typically makes use of ionic liquids 19 which have several drawbacks in terms of cost and toxicity20. This strongly limits their potential applications in commercial devices.Up to now, few reconfigurable examples of microwave absorbers based on electrolyte-gated graphene have been proposed22. They have recently gained increasing attention, in particular in regard to metal-catalysis and organometallics23, energy technology24, electrochemistry25, and nanomaterials growth26, with surprising and unexpected results. In what follows, we demonstrate that DESs represent a valid, low-cost alternative to ionic liquids for realizing a graphene capacitor with a suitable electrochemical window. Specifically, we investigated the hydrophilic ChCl/Gly (1:2 mol/mol) eutectic mixture (melting point −35 °C) as the electrolytic medium. ChCl, also known as vitamin B4, is one of the most widely used ammonium salts extracted from biomass or synthesized from fossil reserves. Thus, it is a very cheap (ca. 2€ kg−1) and biodegradable material, and is produced on the scale of a million metric tonnes per year.In this paper, we take a step forward on the path towards innovative and reconfigurable “optically transparent” graphene-based devices, overcoming both limitations. We propose an optically transparent, flexible and reconfigurable microwave absorber using two main strategies/approaches: (i) an electrolyte-gated graphene capacitor exploiting a Deep Eutectic Solvents (DES) as electrolytic medium and (ii) a “quasi-metal” graphene microwave mirror. In particular, we first propose DESs as electrolytic media for tuning sheet resistance and Fermi level of graphene in order to fully control its microwave response . DESs, which share several physical-chemical properties with traditional ionic liquids , are biodegradable fluids usually made by mixing and gently heating two or three safe and inexpensive components. DES components, often solid compounds at room temperature, are able to interact with each other mainly through hydrogen-bonding interactions, thereby forming eutectic mixtures whose eutectic point temperature is far below those of the individual components. Common mixtures derive from a quaternary ammonium salt  and a neutral hydrogen-bond donor such as glycerol (Gly), urea and natural carboxylic acids. Because of their minimal ecological footprint, in the last few years DESs have been progressively replacing common and toxic volatile organic compounds in several fundamental and applied processes2 that allows the realization of graphene sheets with very low sheet resistance (down to less than 20 ohm/sq)27 that can be implemented as efficient microwave mirror 13.On the other hand, the realization of “quasi-metal” graphene microwave mirror takes advantage of the chemical protocol based on SOClWe thus show that microwave transmittance, reflectance and absorption of the graphene capacitor using the above ChCl-based eutectic mixture can be varied by about 24%, 10% and 15% over the X and Ku bands when an electrochemical window in the −1.4/+1.4 V range is considered. Finally, we numerically and experimentally prove that the DES-gated graphene capacitor can be integrated in a Salisbury screen configuration leading to near perfect absorption with a modulation of about 20%. These results may open the floodgates to unprecedented fully transparent devices for several applications ranging from multi-physics regulation, cloaking, to stealth and other systems.p-doped) and conduction band (n-doped), respectively.Figure The modulation range of graphene electrodes is determined by both graphene structural quality and electrolyte type. The specific electrochemical window of the electrolyte  defines the maximum charge density that can be injected in graphene. On the other side, the quality of graphene electrodes limits the minimum Rs value achievable within the electrochemical windows. We realized an electrolytic capacitor based on double-layer (2L) graphene electrodes. Figure The inset in Fig. D. A VD located at positive or negative voltages is indicative of an intrinsic p- or n-doping state. This intrinsic doping can result from graphene chemical defects and charge transfer from the substrate, the electrolytic medium and charged impurities adsorbed on graphene. The 2L electrode reaches the maximum resistivity value at −0.3 V. When a Vg equal to VD is applied, the Fermi Level is located at the Dirac point, and the material presents the minimum carrier concentration. Then, for Vg > VD or Vg < VD, the material becomes electrically n- or p-doped, respectively, and its Rs decreases. In the exploited electrochemical window (from −1.4 to 1.4 V), the 2L electrode, the Rs modulation range is shifted in the 1700-416 ohm/sq range with a modulation ratio around 4. It is worth noting that the electrochemical window is fixed in the −1.4 to 1.4 V range in order to avoid electrolyte oxidation or reduction at electrode surfaces.The voltage at which the resistivity reaches the maximum value is defined as Dirac voltage, V28.To assess the performance of graphene-base (or G-based) capacitor in the microwave range, we developed a 3D numerical model by means of Comsol-Multiphysics. Figure 20 mode). We set the permittivity and the thickness of the DES equal to 40 and 100 microns, respectively. The contribution of the PET that supports the graphene in the experiments is neglected since it is almost “transparent” in the frequency range of interest.We consider mono-modal propagation in the metallic rectangular waveguide and limit our analysis to the frequency range between 7 GHz and 13 GHz . These results fully confirm that the difference between the front and bottom electrodes is negligible and, hence, the fitted model of Equations 13. Figures 13. Therefore, we determined the absorption A = 1 − R (R = |S11|2) in both cases. Both numerical maps show that the absorption of the Salisbury screen reaches near perfect absorption when Vg = 0 V at about 8 GHz. As Vg increases, the absorption drops down by about 25% (to the detriment of the reflection). Experimental results reported in Fig. Finally, the proposed graphene-based capacitor was used to implement an optically transparent Salisbury screen configuration as sketched in Fig. Maximum absorption of about 97.80% and 99.98% is achieved for the graphene-based and metallic mirrors, respectively. When the absorption higher than 90% is considered, Fig. 28 allows us to extend these concepts to different microwave frequencies and bands.In this paper, we demonstrate the possibility to realize reconfigurable and optically transparent microwave absorbers. This goal was achieved by exploiting highly-doped graphene mirrors operating in the quasi-metallic region and DES-gated graphene capacitors. The combination of these two building blocks allowed us to realize reconfigurable (i) surfaces and (ii) absorbers. Numerical and experimental findings show the ability of these two devices to nearly fully control microwave transmittance, reflectance and absorption of graphene over the X and Ku bands. It is worth highlighting that the independent behaviour of the graphene in the microwave regionTherefore, these results are a mere first step towards innovative and reconfigurable, optically-transparent, graphene-based devices. The flexibility of the proposed surface on flexible substrates could be useful for several applications, such as cloaking and electromagnetic anti-pollution systems, modulators and polarizers. We believe these findings pave the way to conceive a plethora of innovative devices that can simultaneously work in the photonic and microwave domains.6 in the L-S-C-X microwave bands29. This is effectively enough to consider both single and few-layer graphene as an interface with a current sheet J . In turn, the microwave absorption only depends on the Rs of graphene sample rather than their thickness. Therefore, the front and the back electrodes were modelled by two surface currents (J =  σ * E) with different sheet resistance13. In particular, Rs values of both front and back electrodes were fitted by means of an asymmetric double sigmoidal function as follows  graphene sample is around 1 nm-thick that corresponds to ∼λ/100 = 428.32763, A = 1445.88832, xc = −0.19967, w1 = 0.80239 w2 = 0.1112, and w3 = 0.21377.where yg = 0 V. This assumption has been verified in the experimental section (“Results and discussion”).As is evident from Eqs  and 2),,2), it i4 and H2 as precursors. Copper substrate was etched in solution of ammonium persulfate and thermal tape was used for transferring graphene onto corning glass or PET substrates. SOCl2 chemical doping of multilayer-graphene on corning glass was performed in a dry chamber at 105 °C for 60 min (by repeating the same treatment after stacking supplementary graphene layer). Graphene sheet resistance was measured using a four-point contact geometry in the Van der Pauw configuration (5 × 5 mm2).Graphene was grown by chemical vapor deposition methodology on 25 μm thick copper foils at 1000 °C using CHThe eutectic mixture of ChCl/glycerol (1:2 mol/mol) was prepared by heating the corresponding individual components to 60 °C under stirring for 10 min until a clear solution was obtained.2 two-layer graphene foil on 120 µm thick PET foil. Conductive silver paste stripes were used as gate contact (bottom electrode) and source/drain contacts (front electrode). Silicone glue was used to electrically isolate the silver contacts and to seal capacitor. Ag contacts covered with silicone glue  act as spacers between the two graphene electrodes. Source and drain contacts with a broad surface area (width above 4 mm) were used in order to minimize contribution of contact resistance during measurements of graphene resistance. Rs of graphene electrode measured by Van der Pauw four-probe system resulted almost equal to Rs value derived by considering source/drain resistance and relative geometric factors. This attested the negligible contribution of contact resistance. Thus, Rs data of graphene electrode as a function of Vg (−1.4 < Vg < 1.4) were derived by source/drain resistance measurements (VSD = 100 mV).Graphene front and back electrodes consist of 45 * 45 mm


Scaffolds are physical substrates for cell attachments, proliferation, and differentiation, ultimately leading to tissue regeneration. Current literature validates tissue engineering as an emerging tool for bone regeneration. Three-dimensionally printed natural and synthetic biomaterials have been traditionally used for tissue engineering. In recent times, graphene and its derivatives are potentially employed for constructing bone tissue engineering scaffolds because of their osteogenic and regenerative properties. Graphene is a synthetic atomic layer of graphite with SP2 bonded carbon atoms that are arranged in a honeycomb lattice structure. Graphene can be combined with natural and synthetic biomaterials to enhance the osteogenic potential and mechanical strength of tissue engineering scaffolds. The objective of this review is to focus on the most recent studies that attempted to explore the salient features of graphene and its derivatives. Perhaps, a thorough understanding of the material science can potentiate researchers to use this novel substitute to enhance the osteogenic and biological properties of scaffold materials that are routinely used for bone tissue engineering. Tissue engineering utilizes the concept of scaffolding to regenerate the bone defects. The technique for addressing these defects that involves the reconstruction or regeneration of bone always desires a temporary porous scaffold. Bone defects that are caused by trauma, congenital malformations, or due to cancerous lesions can best be therapeutically managed by bone tissue engineering scaffolds. The ultimate aim of modern tissue engineering is to replace the traditional medical procedures involving the repair and regeneration of tissues with three-dimensional scaffolds. These scaffolds have a porous surface that serve as a medium, over which cells can grow rapidly and develop into tissues that are viable. The scaffolds with unique morphology and structural architecture encourage the cells to regenerate bone tissues of extra cellular matrix ,2. IdealThe polymeric scaffolds have excellent biocompatibility and biodegradability, but lack the ability to withstand the forces acting upon. In order to improve their mechanical strength, many researchers have incorporated graphene derivatives within the polymers. Besides enhancing the physical properties, the graphene derivatives also promote cell proliferation and differentiation, owing to their excellent biocompatibility under limited concentrations.Graphene is a single layer of aromatic carbon atoms that are arranged in a two-dimensional lattice ,18. Rese2 bonded carbon atoms arranged in honeycomb lattice structure. Boehm et al. described graphene in 1986 [Graphene is a synthetic atomic layer of graphite with SP in 1986 . In 2004 in 1986 ,22. Grap in 1986 ,26,27,28 in 1986  spans th in 1986  because  in 1986 ,32.Graphene oxide, aids in bone regeneration by enhancing the osteogenic differentiation of progenitor cells. This is accomplished by hydrophobic and electrostatic interactions with the proteins of the microenvironment ,33,34. GVarious biomaterials have been researched as scaffold materials for bone tissue engineering. Biocompatibility, biodegradability, and sufficient mechanical strength to withstand the forces acting upon are the three key factors to be considered for the selection of a scaffold . DependiNatural biomaterials that are used in bone tissue regeneration include proteins like silk, collagen, gelatin, fibrin, fibrinogen, elastin, keratin, actin, and myosin. On the other hand, polysaccharides, such as chitosan, hyaluronic acid, alginate, agarose, cellulose, amylose, dextran, chitin, and glycosaminoglycan’s; and, polynucleotides, like DNA, RNA, chitosan, hyaluronic acid, alginate, and agarose are also being utilized . The afoNishida et al.  coated cAnother study showed that the addition of graphene oxide or reduced graphene oxide to collagen scaffolds increased the tissue compatibility and bioactivity. In vivo studies showed that reduced graphene oxide is more bioactive than graphene oxide when coated on collagen scaffolds . DinescuNair et al.  incorporSynthetic polymers are the commonly used materials for tissue regeneration due to their porosity, quicker degradation time, and superior mechanical strength. They have advantages over natural polymers, like longer shelf-life, cost effectiveness, ability to be tailored to obtain desired shape by milling and printing, can quickly be mass produced under controlled conditions, possess better cell differentiation properties, pore characteristics, and mechanical properties . HoweverPolycaprolactone is a polymer with melting temperature of 60 °C and it is hydrophobic in nature . PolycapPolyvinyl alcohol is another synthetic biodegradable polymer that is soluble in water and hydrophilic in nature. Poly vinyl alcohol (PVA) is used in biomedical application combined with graphene oxide in the form of three-dimensionally printed scaffolds ,66. PolyWei et al.  producedAli et al.  preparedBioactive glass has been widely used in the field of bone tissue engineering because of its ability to form bioactive hydroxyapatite layer, thereby forming a strong bond between implant and the surrounding bone ,75. The Cheng et al.  combinedGraphene, a two-dimensional (2D) nanomaterial has set an enormous trend in research and development in the burgeoning field of biomedical application and bone tissue engineering. Despite their potentiality, very few researchers have attempted to use graphene in human stem cell research. Most of the studies that were done with graphene had focused on increasing the proliferation, adhesion, and growth of stem cells. There has to be a controlled proliferation and differentiation of the stem cells in order to attain successful bone regeneration. This can be achieved with the help of growth factors and osteogenic inducers . Human bLuo et al.  stated tThere are various factors to be considered in designing a scaffold for bone tissue engineering. Although some of the biomaterials that were previously used as a scaffold in clinical trials are available in the commercial market, the methodology and their applications are not always well-balanced. Graphene with its unique properties are potentially validated to be used as bone tissue engineering scaffolds. Research on the contribution of graphene derivatives to bone tissue engineering is still modern, and various studies are ongoing to understand them better. Numerous studies in stem cell research are being conducted in order to explore graphene for its osteogenic potential, and proliferation and differentiation of stem cells. Despite its advantages, graphene derivatives are subjected to few challenges. The toxicity of graphene at higher concentrations and non-biodegradable nature needs further investigations. The interaction of graphene with the biologic cells is yet to be further evaluated in depth. Literature should furnish a wide range of comparative studies in the future, between graphene and the other biomaterials before commercializing them in the market. Concurrently, many in vivo studies involving graphene needs to be tested to understand the exact metabolic pathways in which graphene interacts with the microenvironment and bone tissue regeneration. The success of bone regeneration depends on the proliferation of stem cells. The availability and affordability of graphene derivatives has led to the outcome of many researchers conducting studies to validate the proliferation and differentiation of stem cells by the incorporation of graphene derivatives. A remarkable aspect of graphene derivatives is that their chemical nature seems to act on the proliferation of stem cells, raising the possibility of favoring this process by modifying the chemical configuration. Cell-based bone tissue engineering requires a cell component from the appropriate origin that could be able to repair the target tissues and also a biocompatible material that provides a three-dimensional scaffold for the chosen cells. The ideal combination of cell and scaffold sources varies in relation to the target tissue to be created. Moreover, there have been recent advances in biomaterial synthesis and fabrication tools resulting in the creation of functional and bioactive scaffolds that stimulate different cell functions. Titanium and synthetic biomaterials are used for the reconstruction of lost bone tissues. Titanium is considered as a best suitable material for bone regeneration due to its mechanical strength and biocompatibility. Although titanium helps in better osseointegration, there are chances of development of fibrous tissues, which may lead to failure of implants. To overcome this drawback, graphene can be coated onto the surface of implants to enhance better osseointegration and bone formation. Although graphene enhances the bone formation, the long term success of graphene coated on to the implant surface is yet to be researched. Attempts had been made to use Graphene as a carrier for delivery of BMP-2 for better osseointegration. Nonetheless, the outcomes in clinical application are questionable. Graphene derivatives have been tried along with synthetic biomaterials and titanium for modular endoprosthesis in reconstruction of fractured and resected bone segments. Perhaps, studies are still in the early stages of in vitro analysis and in vivo experiments are yet to be conducted. Prospective in vitro and in vivo studies can be helpful to elucidate the full mechanisms of action of the actual available configurations of graphene-based scaffolds. Indeed, the foreseeable future can take advantage of this carbon material to be used as a promising scaffold for bone tissue engineering.


We report a unique constant phase element (CPE) behavior ( The electrolyte–graphene interface plays a critical role in many promising applications of graphene, such as supercapacitors ,2, biosenterface . Experimnterface  first menterface  and aquenterface ,11,12.These studies have revealed the voltage-dependence of the electrolyte–graphene interfacial capacitance; however, the measurements in most of these studies were performed at fixed frequencies, or within limited frequency ranges, thus failing to display the complexity of the capacitive behavior of the electrolyte–graphene interface. Typically, the liquid–solid interface does not behave as an ideal capacitor but is usually considered as a constant phase element (CPE), with the impedance ( follows :(1)Z=1Q0 reports ,14,15. I reports .In this work, we studied the frequency response of the electrolyte–graphene interface using electrochemical impedance spectroscopy (EIS), and revealed a unique CPE behavior of the electrolyte–graphene interface, showing both The schematic experimental setup in an electrode configuration is shown in The schematic experimental setup in a transistor configuration is depicted in The microscopic images of the graphene electrode and the graphene transistor are shown in the inset of f is the faradaic impedance, and Zw is the Warburg impedance, which is attributed to the diffusion-limited faradaic reaction. The fitting yields a CPE with −9 S·sα and α = 0.89 which corresponds to the capacitive regime with a phase shift of ~−80° in the frequency range of 100–1000 Hz. The results suggest that the electrolyte–-graphene interface behaves as a CPE rather than an ideal capacitor.We first studied the frequency response of the graphene electrode using EIS. −9 S·sα at 2 substrate and the defects in the graphene lattice, which could introduce residual carriers [Using the Randles circuit model, the impedance spectrum of the graphene electrode was analyzed at different gate voltages. To be consistent with the measured results in the transistor mode, in  reports ,8,10. Thcarriers . Howeverf and Zw can be removed leading to a simplified Rs-CPE circuit with the impedance calculated asThe Randles circuit model was shown to be well fitting to the impedance spectrum. However, it might also introduce uncertainties to the fitting result because a quite few fitting parameters were involved, and this could possibly lead to the observed The out-of-phase CQ=2eConsidering the series arrangement of the EDL capacitance  and . The expinset of b. The fi reports ,21. Comp (7) and . The expThe carrier mobility can be extracted based on the Drude model:acitance b. Based 2V−1s−1, for holes and electrons, respectively, and decreases when the carrier density is higher than ~1.5 × 1012 cm−2. The results suggest the transition of the scattering mechanism from the long-range Coulomb scattering  near the Dirac point to the short-range scattering, which is in agreement with the self-consistent theory [The sheet conductivity of graphene was calculated based on the transfer measurement of the electrolyte-gated graphene transistor after evaluating the access resistance shown in t theory . Our rest theory ,24, whicIn summary, we study the unique CPE behavior of the electrolyte–graphene interface with both


The excitement of graphene  has generated numerous procedures for the fabrication of graphene. Here we present a mini-review on a rather less known, but attractive, in situ means to fabricate graphene inside a transmission electron microscope (TEM). This is achieved in a conventional TEM (viz. no sophisticated specimen holders or microscopes are required) and takes advantage of inherent hydrocarbon contamination as a carbon source. Both catalyst free and single atom catalyst approaches are reviewed. An advantage of this technique is that not only can the growth process be imaged in situ, but this can also be achieved with atomic resolution. Moreover, in the future, one can anticipate such approaches enabling the growth of nano-materials with atomic precision. There are numerous routes with which to obtain graphene which include mechanical exfoliation ,3,4,5,6,−9 mbar), a gas molecules mean free path is ca. 40 km! [−7 mbar (HV) and thus while contaminant molecules in the chamber are reduced they are not removed. Moreover, in addition to contamination from the TEM vacuum chamber , the sample itself can introduce additional contamination and moreover, even if not, the sample itself can adsorb contaminants prior to insertion in the TEM. Specimen based contamination is considered the main contributor, in particular, for hydrocarbon contamination [High vacuum (HV) and ultra-high vacuum (UHV) systems by their nature are designed to, in essence, pump-for-nothing, viz. the goal is to have nothing, or at the very least as few as possible atoms and/or molecules. This in practice is hard to achieve as atoms and molecules tend to adsorb or stick to any surface they come in contact with. As one pumps or evacuates a vacuum chamber adsorbed material can desorb. This desorption can be accelerated by heating the surface. However, once material desorbs it has a very high probability of colliding with a chamber wall again as in a vacuum the mean free path of a gas atom/molecule is large. For example, in UHV  and the process becomes more relevant as the irradiating electron energy (Eo) decreases. It also depends on the bond type of the specimen or contaminant. Heating which also arises due to inelastic scattering occurs because electrons have similar mass and thus significant energy can be transferred leading to a local temperature rise. Heating increases with increasing electron current density and varies with the material’s thermal conductivity. Knock-on damage is an elastic scattering event between the irradiating electrons and the sample or contaminant atom nucleus. Since the event is elastic there is no change in the irradiating electrons energy, however, energy is transferred from the irradiating electrons since the electrons are deflected by the atom nucleus and so, to conserve energy and momentum, some energy must be transferred. This is akin to bremsstrahlung radiation, except here, the energy release is not in the form of an X-ray, rather energy transfers as momentum to the atom and can be sufficient to remove the atom itself, hence the term sputtering. The process depends on the incoming electron energy and knock-on damage threshold of the material.In terms of the electron sample interactions (scattering) at the sample, they can be classified into elastic and inelastic events. When an electron from the TEM electron beam undergoes an electrostatic deflection by the Coulomb field of an atom in the sample, this is referred to as elastic scattering. In the case of inelastic scattering, a Coulomb interaction of incoming electrons with electrons surrounding the atoms forming the specimen takes place. These processes are of course important for imaging and diffraction in electron microscopes . They caOf the published data there are two primary approaches to take advantage of (contaminant) hydrocarbon species inside a TEM column as a carbon feedstock for graphene synthesis driven by the electron beam. In the first process no catalyst is required, but can be considered a two-step process where initially carbonaceous material is formed through electron beam induced deposition, and then graphitized with further electron beam irradiation . In the second process, a catalyst  is used to presumably aid cracking (decomposition) of the hydrocarbon and growth of graphene. We first review the case of catalyst free grown graphene and then catalyst assisted growth of graphene. It is also worth pointing out at this stage that all the experiments reviewed here were conducted at room temperature, and calculations show that in all cases the temperature increase due to electron beam irradiation is negligible.2 carbon onions form  [As mentioned above in this graphene fabrication process, two steps are required . In the h other) ,39. The h other) . Howeverh other)  in whichh other) ,42,43.In summary, in this two-step process, amorphous carbon is first deposited by EBID in the STEM mode, and then graphitized through radiolysis reactions by the electron beam in the TEM mode.In the case of catalyst assisted growth of graphene from hydrocarbon contaminants inside a TEM, thus far, all reported cases were conducted at 80 kV in the high resolution TEM (HRTEM) mode. Chronologically, the first reported case was that in which a single Fe atom at a graphene edge would diffuse or move along the edge while under electron irradiation . The difA more recent study by Ta et al, explored Cr atoms at the open edge of graphene layers while under electron beam irradiation (80 kV) . Again tSuch studies are important to better comprehend single atom growth of graphene  and could lead to precision growth of nano-materials at the atomic scale.In this mini review we presented two primary routes in which contaminant molecules, in particular hydrocarbons, present inside a TEM can be used as a carbon source for in situ graphene synthesis driven by electron beam irradiation. Two primary approaches are presented. In the first, a two-step procedure is followed in which hydrocarbon contaminants are decomposed by the electron beam (in STEM mode) to form an amorphous carbon film  over a support. In the second step, the amorphous carbon is transformed to graphene layers parallel to the support surface by an electron beam in the TEM mode. This graphene synthesis procedure does not require a catalyst, while the second approach does, and implements a single metal atom catalyst for the graphitization process. In effect, a single metal atom (Fe or Cr) at an open edge graphene is able incorporate C atoms (growth) as it diffuses along the graphene edge.These studies are important in that they help us understand the growth of graphene at the atomic scale and also pave the way for techniques to study single atom catalysis. Such work can lead to atomically precise growth of 2D materials which could have important implications for the microelectronics industry. Moreover, it is conceivable that such work could be used for lateral hetero 2D materials, for example, stitching graphene into hBN.


Idiopathic pulmonary fibrosis (IPF) is a progressive fibrotic interstitial lung disease, with high mortality. Currently, the aetiology and the pathology of IPF are poorly understood, with both innate and adaptive responses previously being implicated in the disease pathogenesis. Heat shock proteins (Hsp) and antibodies to Hsp in patients with IPF have been suggested as therapeutic targets and prognostic biomarkers, respectively. We aimed to study the relationship between the expression of Hsp72 and anti-Hsp72 antibodies in the BAL fluid and serum Aw disease progression in patients with IPF. n = 107) and other interstitial lung disease (ILD) patients (n = 66). Immunohistochemistry was used to detect Hsp72 in lung tissue. The cytokine expression from monocyte-derived macrophages was measured by ELISA.  A novel indirect ELISA to measure anti-Hsp72 IgG was developed and together with commercially available ELISAs used to detect Hsp72 IgG, Hsp72 IgGAM, and Hsp72 antigen, in the serum and BALf of a cohort of IPF (n = 107) and other ILDs (n = 66). Total immunoglobulin concentrations in the BALf showed an excessive adaptive response in IPF compared to other ILDs and healthy controls (p = 0.026). Immunohistochemistry detection of C4d and Hsp72 showed that these antibodies may be targeting high expressing Hsp72 type II alveolar epithelial cells. However, detection of anti-Hsp72 antibodies in the BALf revealed that increasing concentrations were associated with improved patient survival . In vitro experiments demonstrate that anti-Hsp72 complexes stimulate macrophages to secrete CXCL8 and CCL18.  Anti-Hsp72 IgG was detectable in the serum and BALf of IPF ( Our results indicate that intrapulmonary anti-Hsp72 antibodies are associated with improved outcomes in IPF. These may represent natural autoantibodies, and anti-Hsp72 IgM and IgA may provide a beneficial role in disease pathogenesis, though the mechanism of action for this has yet to be determined. Idiopathic pulmonary fibrosis (IPF) is the most common interstitial lung disease (ILD) with an estimated prevalence of 10-60 cases per 100,000 people worldwide –4. A mul+ T cells only proliferated in response to protein samples prepared from IPF lung tissue and not healthy tissue [−/−Rag mice did not result in ILD. However, the transfer of BPIFB1-specific CD4+ cells led to spontaneous ILD induction which was not observed in mice with intact immune systems [A role for IgG in IPF pathology was originally postulated when detection of complement activation through the classical pathway was seen in the pleural space  and immuy tissue . Circulay tissue , 17. Mory tissue  but havey tissue  and cytoy tissue , 20, pery tissue , and vimy tissue  BPIFB1 [y tissue . Certainy tissue . The tra systems . This su systems .The presence of IgG autoantibodies is generally considered to represent a breakdown of self-tolerance and is associated with pathological consequences. Alternatively, these antibodies may instead represent IgG “natural” autoantibodies that have been described in healthy individuals  and may Ethical permission was granted from the NHS Lothian Research ethics board (LREC 07/S1102/20 06/S0703/53). Participants were incident cases attending the Edinburgh Lung Fibrosis Clinic. Serum samples were obtained at first presentation to the clinic, and BAL was obtained within the first 12 months of first presentation, patient demographics used in this study are in Commercial anti-Hsp72 IgG assays were not available at the time of study; thus, anti-Hsp72 IgG was measured using an in-house optimised indirect ELISA, using the ILD patient serum as a source for the anti-Hsp72 IgG standard. The serum from 5 patients was pooled to generate the anti-Hsp72 IgG standard and was determined using the method described below and identified by the increased 450 nm OD readings measured. To briefly describe, 100 ng/ml recombinant (r)Hsp72  was incubated overnight at 4°C in an ELISA plate. Between each of the following steps, 3 washes were made using PBS with 0.1%Tween. ELISA plates were blocked using RD . Patient samples were optimised for the assay; serum samples were diluted 1 : 1000 and BALf samples 1 : 100 in RD and incubated for one hour . Detection of anti-Hsp72 IgG was performed using a biotin-conjugated anti-human IgG , incubated for 2 hours. HRP-conjugated streptavidin  was incubated at the appropriate concentrations, and TMB-HRP reactions were measured using a BioTek Synergy H1 Hybrid Plate Reader.ELISAs for CXCL8 (DY208), Hsp72 (DY1663), and CCL18 (DY394) were sourced from R&D . ELISA for total IgG (88-50550), total IgA (88-50600), and total IgM (88-50620) was sourced from Affymetrix eBioscience . ELISAs for anti-Hsp72 IgGAM (ADI-EKS-750) were sourced from Enzo Life Sciences . These ELISAs were used following the manufacturers' protocol.μl Tris (pH 8).BALf IgG from 6 IPF patients was purified using Protein G . For each patient, 4 ml of BALf was diluted 1 : 1 with Protein G binding buffer  and allowed to gravity filter through Protein G agarose. Purified IgG was eluted using 2 ml elution buffer , and the pH was stabilised with 100 PBMCs were isolated from whole blood using a standard Ficoll-Paque isolation method. Whole blood was diluted 1 : 1 with sterile PBS. Diluted whole blood was then layered over Ficoll at a 3 : 1 ratio of volume (3 ml of blood per 1 ml of Ficoll). Samples were then centrifuged at 1500g for 20 minutes without braking. After centrifugation, cells were collected, washed in PBS, and counted prior to monocyte isolation.+/CD16−, CD14−/CD16+, and CD14+/CD16+ monocytes were negatively selected from the PBMCs using a Pan-monocyte isolation kit  following the manufacturer's protocol. Isolated monocytes were differentiated into MDMs by culturing them for 4 days in a 96-well culture plate in IMDM supplemented with 10% FBS, 1% L-glutamine, 100 μg/ml penicillin, 100 IU/ml streptomycin, 2% AB serum, and 5 ng/ml M-CSF. Following 4 days of culture, MDMs were treated with the following conditions for 24 hours: untreated, 100 ng/ml Hsp72 , 1 μg/ml and 10 μg/ml monomeric Hsp72 IgG , 1 μg/ml and 10 μg/ml of monomeric isotype IgG1 , 1 μg/ml and 10 μg/ml Hsp72-IgG complex (generated by incubating the Hsp72 and Hsp72 IgG1 antibody at a 1 : 3 ratio for 20 minutes prior to MDM treatment), 50 ng/ml LPS, and 1 μg/ml IPF patient BALf IgG (with and without preincubation with 100 ng/ml Hsp72). Cell culture supernatant was retrieved after 24 hours of MDM cell treatment for analysis.CD14Immunohistochemistry for Hsp72 and C4d was performed on UIP and chronic HP lung biopsies. Hsp72 staining was performed by the SURF Immunohistochemistry using a BOND-MAX Automated Immunostainer at the QMRI, Little France, Edinburgh. C4d staining was performed using a BOND-MAX Automated Immunostainer by NHS Lothian at Edinburgh Royal Infirmary. Hsp72 staining used a peroxidase-DAB method, and C4d staining used an alkaline phosphatase staining method.Nonparametric statistical tests were used where indicated. Kaplan-Meier (KM) survival and a Cox proportional hazard regression analysis were used for patient survival analysis, and hazard ratios (HR) adjusted for patient clinical data were made.p = <0.0001). Both IPF and other ILD patients had elevated serum IgA compared to healthy controls (p = 0.016). In the IPF cohort, patients can be split into “progressor” and “nonprogressor” subgroups, with IPF progression defined as ≥10% loss in VC or IPF-related death within 12 months of sampling. When the IPF cohort was split into these two subgroups, it was found that IPF progressors had an elevated concentration of serum IgG (p = 0.043). Conversely, in the BALf, elevated concentrations of IgG and IgA were found in IPF patients compared to healthy controls . IPF patients were also found to have elevated IgG, but not IgA, compared to other ILDs. When comparing IPF patient subgroups, no differences were found in the BALf immunoglobulin concentrations.IPF is not considered a classical autoimmune disease; however, it has been reported that IPF patients express some features of classical autoimmunity such as elevated CXCL13 expression . Increasp = 0.002), with no difference between ILD patient subgroups. Hsp72 concentrations measured in the BALf were not significantly different between ILD patients and healthy controls  or anti-Hsp72 IgGAM concentrations (p = 0.24). There was no difference in anti-Hsp72 IgG or IgGAM serum concentrations when patients were split into progressors and nonprogressors . Anti-Hsp72 IgGAM was not measured in other ILD patient serum and BALf. We observed significantly lower concentrations of anti-Hsp72 IgG (p = 0.014) and anti-Hsp72 IgGAM (p = 0.005) in IPF progressors compared to nonprogressors.No significant difference was observed in BALf anti-Hsp72 IgG between IPF and other ILD patients .Patients were dichotomised into high expressing and low expressing patients according to the median value to generate a Kaplan-Meier (KM) survival curve . In the LCO, no significant association was identified for total BALf IgA and survival but increased BALf anti-Hsp72 IgGAM was associated with improved patient survival .Using a Cox proportional hazard model, and after adjusting for age, sex, smoking status, percentage-predicted VC, and percentage-predicted Tp = 0.031). CCL18 secretion had no changes when cultured with IPF patient BALf IgG with and without Hsp72; under both conditions, there was a 4-fold increase in CCL18 secretion compared to untreated cells . It hasReg lymphocytes [The provenance of anti-Hsp72 antibodies in the lungs of IPF patients is uncertain. We speculate that anti-Hsp72 immunoglobulins in the lung are natural, as they are detectable in healthy controls, but we cannot rule out that the pulmonary antibodies in particular do not arise until after disease onset. The establishment of organised and proliferative B cell germinal centers in IPF lungs , 10 and phocytes . The preγ receptors, it seems highly likely they would be cardinal cells to respond to a functional antibody in IPF. We found that MDMs treated with IgG isolated from patient BALf secreted more CXCL8 when exposed to Hsp72 than those cells treated with the IgG alone. This was also true using commercial anti-Hsp72-derived antibodies (supplementary γRIIa and FcγRIIIb in IPF patients may alter macrophage responses [γR expressing cells, such as neutrophils.Macrophages are reportedly activated in IPF , 39, 40,esponses , 42. FurThe focus of autoimmunity in IPF, often targeting epithelial antigens, has conventionally been hypothesised as being pathological in nature. Here, we report that elevated serum IgG is a feature of IPF, in keeping with other classical autoimmune diseases. However, the intrapulmonary autoantibody to Hsp72 may have a protective role. We speculate that anti-Hsp72 IgG is natural in origin and promotes a homeostatic immune response.


Arabidopsis, some introns are longer than 10 kilo base pairs (bp) and others are predicted to be shorter than 10 bp. To identify the shortest intron in the genome, we analyzed the predicted introns in annotated version 10 of the Arabidopsis thaliana genome and found 103 predicted introns that are 30 bp or shorter, which make up only 0.08% of all introns in the genome. However, our own bioinformatics and experimental analyses found no evidence for the existence of these predicted introns. The predicted introns of 30–39 bp, 40–49 bp, and 50–59 bp in length are also rare and constitute only 0.07%, 0.2%, and 0.28% of all introns in the genome, respectively. An analysis of 30 predicted introns 31–59 bp long verified two in this range, both of which were 59 bp long. Thus, this study suggests that there is a limit to how small introns in A. thaliana can be, which is useful for the understanding of the evolution and processing of small introns in plants in general.Most eukaryotic genes contain introns, which are noncoding sequences that are removed during premRNA processing. Introns are usually preserved across evolutionary time. However, the sizes of introns vary greatly. In  Introns are important features of eukaryotic genes. They are usually noncoding sequences in the gene and have to be removed from the premRNA . The bouArabidopsis .The plant materials used in this study were Columbia-0 (Col-0) ecotype Arabidopsis was obtained from the TAIR website . The detailed structure information on individual genes was also searched and checked manually on the TAIR website. Gene expression levels at different developmental stages were checked by looking up the microarray data  and calculated manually one by one.For RT-PCR analysis, mRNA was first reverse transcribed with the RevertAid First Strand cDNA Synthesis Kit . cDNA was amplified with the corresponding primers  online bArabidopsis genome and our previous analysis , some of these 103 very small introns were removed, leaving only 71. The distribution of their lengths is shown in According to the new version of the annotated http://jsp.weigelworld.org/expviz/expviz.jsp; last accessed September 11, 2018). In the beginning, we amplified the genes with relatively high expression levels, then analyzed the genes with a lower expression level and those with expression close to the basal level. A few of the genes had multiple bands  and S28 (AT3G23080.2-4) were proven to be true intron. At 59 bp each, they are the smallest introns found in this study.Although almost all of the very small introns were not confirmed, we found some introns that are also relatively very small. For example, in the analysis of the predicted intron AT1G71280.1-2, we used cDNA sequencing to confirm that the control intron AT1G71280.1-1 is 66 bp  and the Arabidopsis in order to find its smallest introns, and found 103 predicted introns that were 30 bp or smaller in the TAIR10 annotation and 71 in the Araport11 annotation. We narrowed these predicted introns into 48 likely candidates and a further RT-PCR analysis amplified cDNA fragments from 31 genes and genomic DNA fragments from 17 genes. However, we found no evidence that any of these candidates actually were introns. A further analysis of 30 selected introns between 30 bp and 60 bp finally verified two small introns of 59 bp.We analyzed the small introns in the genome of Arabidopsis was sequenced and annotated at very high quality, it is not error free. Arabidopsis is a higher plant and its genome is ∼130 Mb in size, making it one of the smallest reported plant genomes (Arabidopsis, suggesting the genome is still complicated (Although the genome of  genomes . More thplicated . Many ofArabidopsis genome, and this provides some useful insights into the smallest introns in plants as a whole. Introns may retract by DNA deletion, but they are usually preserved during evolution. There is probably a lower limit of the size of introns, but 30 bp seems to be too small. There are several hundreds of predicted introns with sizes from 30 to 60 bp, and these also constitute a very small percentage of the total introns in the genome. The rarity of these predicted introns 30–60 bps long in combination with our results puts doubt on their existence. A further analysis of 30 selected introns in this range only verified two introns of 59 bp, and the true smallest introns in the Arabidopsis genome are probably close to this size. That there are many more introns 60–69 bp than 50–59 bp long (Our data suggest introns of 30 bp or smaller seem to not exist in the  bp long  also supH.G. and W.C. designed the study; W.C., Y.Z., and X.M. carried out the experiments; W.C., Y.Z., X.M., and H.G. analyzed the data; W.C., C.A., and H.G. prepared the manuscript.Supplementary DataClick here for additional data file.


Without compounding with magnetic materials or conductive polymers, Gmfs show outstanding MA performance with the aid of rational microstructure design. Furthermore, Gmfs exhibit advantages in facile processibility and large-scale production compared with other porous graphene materials including aerogels and foams.Graphene has shown great potential in microwave absorption (MA) owing to its high surface area, low density, tunable electrical conductivity and good chemical stability. To fully realize grapheneʼs MA ability, the microstructure of graphene should be carefully addressed. Here we prepared graphene microflowers (Gmfs) with highly porous structure for high-performance MA filler material. The efficient absorption bandwidth (reflection loss ≤ −10 dB) reaches 5.59 GHz and the minimum reflection loss is up to −42.9 dB, showing significant increment compared with stacked graphene. Such performance is higher than most graphene-based materials in the literature. Besides, the low filling content (10 wt%) and low density (40–50 mg cmThe online version of this article (10.1007/s40820-017-0179-8) contains supplementary material, which is available to authorized users. Graphene microflowers (Gmfs) for outstanding microwave absorption performance are produced via a three-step protocol.The porous Gmfs show a broad efficient absorption bandwidth of 5.59 GHz with a minimum reflection loss of −42.9 dB, outperforming most graphene-based materials ever reported.−3) of Gmfs are favorable for their practical applications.The mass productivity, low filler content (10%) and low density  of −30 dB. Feng et al. [2O4 with SiO2 and RGO, which exhibited an EAB of 6 GHz and a minimum RL of -43.9 dB. However, no attention has been paid to the microstructure design of individual graphene, which might have a great impact upon the MA performance. Compared with layered structure, folded graphene assemblies with high porosity can induce the multi-reflection loss of microwave [MA materials can be classified into magnetic, dielectric and electric conductive categories according to the absorption mechanisms , 7, 8. Treported –12. In sreported , 14. Amoreported –18. Unforeported  reportedreported –22 reporreported  designedg et al.  coated Zicrowave .2 g−1 and a low density of 40–50 mg cm−3. The maximum EAB reaches 5.59 GHz and the minimum RL is up to -42.9 dB, which is higher than pure graphene fillers and most graphene-based materials in the literature. Moreover, the low filler content (10 wt%) indicates high cost efficiency, benefiting practical applications. The excellent MA ability of Gmfs is attributed to the skeleton microstructure, which can not only promote the attenuation of microwave by multi-reflection between graphene layers, but also favor the formation of conductive network.Herein, we fabricated porous Gmfs powder with high MA performance. Folded graphene sheets assemble together into flower-shaped microparticles, forming a skeleton structure with a high surface area of 230 mhttp://www.gaoxitech.com/). All reagents were purchased from Sinopharm from Chemical Reagent Co., Ltd., and used as received. Commercialized graphene powder (CG) was purchased from Asfour (http://www.asfour.com.tw/).Aqueous suspension of single-layer graphene oxide (GO) with a thickness of 0.8 nm and average lateral sizes of 40–50 μm was commercially available from Gaoxitech  was prepared via a spray-drying procedure. The obtained 4 mg gOne gram of fGO was sealed in a glass pot with the addition of 5 drops of hydrazine. The glass pot was kept in the 80 °C oven for 12 h. The obtained reduced fGO turned from yellow to black. Afterward, the reduced fGO was annealed in the tube furnace. The temperature increased from room temperature to 1300 °C in 160 min and kept under that temperature for 1 h to get Gmfs. The protective gas was nitrogen.CG was annealed in a tube furnace, following the same procedure of fGO.−1 heating rate under nitrogen atmosphere. All samples were heated under 120 °C for 15 min to remove the residual water.The morphologies of the samples were obtained from a Hitachi S4800 field emission scanning electron microscopy (SEM) system. High-resolution transmission electron microscopy (HRTEM) images were collected on a JEM-2010 HRTEM with an accelerating voltage of 120 kV. Nitrogen cryoadsorption was measured on AUTOSORB-IQ-MP . All samples were outgassed under 120 °C for 1 h. Raman spectra were recorded on a Labram HRUV spectrometer operating at 514 nm. X-ray diffraction (XRD) pattern was measured with an X’Pert Pro  diffractometer using monochromatic Cu Kα radiation (λ = 1.5406 Å) at 40 kV. X-ray photoelectron spectroscopy (XPS) studies were carried out using a PHI 5000C ESCA system operated at 14.0 kV. All binding energies were referenced to the C 1s neutral carbon peak at 284.8 eV. Thermogravimetric analyzer  was performed from room temperature to 850 at 10 °C minRL of microwave can be calculated as follows:Zin refers to the normalized input impedance of a metal-backed microwave absorbing layer, μr and εr represent the complex permeability and complex permittivity, respectively, f is the frequency of microwaves, d is the thickness of the absorber and c is the velocity of light in free space.The complex permittivity was tested via a coaxial line method. Gmfs and CG were mixed with paraffin under different filler contents and shaped as cylindrical toroidal specimens with an outer diameter of 7.0 mm, inner diameter of 3.04 mm and thickness of 4.0 mm. The preparation of the composites was conducted by simply mixing melt paraffin and the fillers with a glass stick. The parameters were obtained from the vector network analyzer. The complex permeability was considered to be that of free space since no ferromagnetic materials were involved. The δ ∝ (φ − φc)t [φc is the percolation volume fraction and t is the critical exponent. φc can be obtained by fitting the logδ–φ curves. The further fitting of logδ versus log(φ − φc) gives t. The transformation between φ and weight fraction (w) follows: φ = wρm/(wρm + ρf), where ρm and ρf are the density of matrix and filler, respectively. Here ρm is the density of paraffin (0.9 g cm−3) and ρf is the density of graphene (2.2 g cm−3).The conductivities of all samples were measured on an electrochemical workstation . According to the percolation theory, the electric conductivity follows the power law:  φc)t , where φAs illustrated in Fig. −3  surface area analysis. The absorption/desorption curves and corresponding pore size distributions are shown in Fig. eak Fig. b. The CG−1) and G band (1580 cm−1), respectively [sp3 carbon in graphene, and G band is related to the graphitic sp2 structure. The intensity ratio of the D and G peak is widely used as a metric of disorder in graphene [ID/IG in Gmfs (0.96) demonstrates a more disordered structure compared with CG (ID/IG = 0.14). Such disorder comes from the defects and functional groups left by the reduction in fGO. XRD pattern of Gmfs has one main peak at 26.1°, corresponding to (002) plane . The XPS patterns of Gmfs and CG show little difference, and the element content of CG is similar with that of Gmfs (95.3% carbon and 4.6% oxygen). From the TGA plots, we find that there is negligible weight loss in Gmfs and CG even under 800 °C . Therefore, the chemical compositions of Gmfs and CG are nearly identical, attributing to the 1300 °C treatment on both materials. The reduction in GO recovers the graphitic structure of graphene and increases the electrical conductivity, benefiting the microwave attenuation. The defects in Gmfs enhance the polarization effect, which may increase the MA ability.In order to examine the MA performances of Gmfs, paraffin was selected to make composites for test due to the good processibility and nearly zero reflection loss of microwave. Gmfs can be compounded with paraffin homogeneously without obvious aggregation or precipitation. As shown in Fig. S5a, b, the small crumpled areas in dark color, representing the embedded Gmfs, distribute uniformly on the fracture surface. CG can also form a uniform composite with paraffin, with some graphene flakes stick out from the cross section . Furthermore, paraffin was dissolved by petroleum ether to evaluate the influence of compounding on the structure of filler materials. It is illustrated that Gmfs keep the flowerlike shape with folded surface after paraffin was washed, and CG is still in multilayered structure . Therefore, the influence of compounding on microstructures of the graphene fillers is negligible.ε) was tested via a coaxial line method. Since there are no magnetic materials in Gmfs, CG or paraffin, the permeability can be regarded as 1. The real parts (ε′) and the imaginary parts (ε″) of all samples were obtained in the frequency range of 2–18 GHz. As demonstrated in Figs. ε′ and ε″ decrease with increasing frequency, attributing to the dielectric relaxation [ε′ and ε″ increase with the increment of filler content owing to the enhanced polarization and electric conductivity. However, the introduction of Gmfs results in a lower increment in complex permeability compared with CG. We calculated the average ε′ and ε″ in the frequency range of 8–18 GHz, as summarized in Table ε′ and ε″ of 3 wt% Gmfs/paraffin are in close proximity with those of 3 wt% CG/paraffin. With filling ratio increasing, the ε′ of Gmfs/paraffin becomes significantly lower than CG/paraffin. 8 wt% CG/paraffin shows a ε′ of 6.96 that is even higher than 10 wt% Gmfs/paraffin. The ε″ of Gmfs/paraffin under different filler contents is also lower, except for 8 wt%. For the filler content of 11%, the ε′ and ε″ of Gmfs/paraffin are 7.56 and 5.44, much lower than those of CG/paraffin. The complex permittivity of carbon materials is determined by the graphitization degree and microstructure [ε′ and ε″ of Gmfs can be ascribed to the defective porous structure, which will be further discussed below. It is well known that ε′ represents the storage capability of the incident electric energy, while ε″ influences the dissipation ability based on electromagnetic theory [ε′ and ε″ are low. In contrast, overhigh ε′ and ε″ lead to the mismatch between air and sample interface. Therefore, the complex permittivity must be optimized to obtain best MA performance.The relative complex permittivity  of Gmfs/paraffin and CG/paraffin was compared, as shown in Fig. ε′ and ε″. The enhanced tangent loss with lower complex permittivity can be attributed to the defective porous microstructure of Gmfs. The reduction in fGO leaves functional groups and defects, which improve the polarization and adjust the conductivity, leading to lower ε′ and ε″. The skeleton structure generates high surface area, which favors the formation of conductive network and multi-reflection loss. In consequence, Gmfs feature high tangent loss with rational ε′ and ε″. It is generally accepted that tangent loss represents the capability of converting microwave to other forms of energy. High tangent loss is beneficial for MA, while high values of ε′ and ε″ are harmful for impedance match. The perfect combination of high tangent loss and reasonable complex permittivity in Gmfs/paraffin gives rise to the high EAB and RL values. Based on the transmission line theory, we can calculate the rational range of ε′ and ε″ by setting the thickness as 2 mm [ε′ and ε″ in 13, 15, and 18 GHz, respectively. RL is below -10 dB when ε′ and ε″ under corresponding frequency fall into these circles. The complex permittivities of Gmfs/paraffin are in all three circles, indicating the EAB values are below -10 in 13–18 GHz and the EAB is broader than 5 GHz. For CG/paraffin, the complex permittivities are out of the circles of 13 and 18 GHz, leading to a narrow EAB.In order to reveal the MA mechanism, the tangent loss , high specific surface area (230 m2 g−1) and low filler content (10 wt%) are beneficial to the demands in lightweight and cost reduction. Besides, the facile processing and scalable production of Gmfs are more favorable for practical applications compared with other graphene materials, such as graphene aerogel and graphene composites. Our findings open the way for preparation of high-performance MA materials by rational designing the porous structure.We developed a novel strategy to assemble graphene into a highly porous structure, resembling microflowers. The obtained GO dispersion was spray-dried into fGO, followed by chemical reduction and thermal reduction to obtain Gmfs with skeleton microstructure. The combination of porosity and disorder in Gmf gives rise to a broad EAB of 5.59 GHz with a minimum RL of −42.9 dB, which is much higher than those of CG and most graphene-based materials in the literature. The low density Below is the link to the electronic supplementary material.


To the best of our knowledge, such an observation reports the clearest conductance quantization in physically etched graphene nanoconstrictions. The fabrication of such high quality systems and the scalability of the cryo-etching method opens a novel promising possibility of producing more complex truly-ballistic devices based on graphene.We report on a novel implementation of the cryo-etching method, which enabled us to fabricate low-roughness hBN-encapsulated graphene nanoconstrictions with unprecedented control of the structure edges; the typical edge roughness is on the order of a few nanometers. We characterized the system by atomic force microscopy and used the measured parameters of the edge geometry in numerical simulations of the system conductance, which agree quantitatively with our low temperature transport measurements. The quality of our devices is confirmed by the observation of well defined quantized 2 It has been demonstrated that the charge mobility can increase by several orders of magnitude in these structures. However, a fully-tunable electronic confinement of charge carriers in graphene, that has been pursued since its discovery2, is still remaining challenging. It turned out that edge imperfections of graphene based systems are so detrimental for the ballistic charge transport that observations of the quantized conductance even in the simplest nanostructures, such as a nanoconstriction (NC), was problematic.Graphene stands out as one of the most promising 2D materials for electronic applications. Initial problems related to the low charge carrier mobility, which were typical for the first standalone graphene samples, have been successfully resolved. For example, it has been demonstrated that the charge mobility can increase by several orders of magnitude by encapsulating graphene between thin layers of diverse 2D materials, such as hexaboron-nitride (hBN)e2/h or 4e2/h spaced conductance plateaus4, the latter has turned into an arduous technological challenge and yielded less clear evidence of quantized conductance. For example, the first mechanically defined NCs were made of graphene deposited directly onto silicon dioxide wafers5. Conductance steps in those systems appeared to be at least an order of magnitude lower than the conductance quantum 2e2/h7, which could be caused by a plethora of different effects such as the Coulomb blockade, high electron back scattering and localization by disorder or charging effects, or by intrinsically low mobility of carriers. Recently, Tombros et al.8 observed 2e2/h steps of conductance in a high mobility constriction produced by current annealing of suspended graphene flakes. The nanostructure was fabricated by passing high electric current through a suspended graphene flake which was deforming into a NC-like structure. The main limitation of the method is purely technological: accurate control of the dimensions of the graphene NC is difficult to attain and, therefore, such nanostructures are not easily reproducible.Up to now, manifestations of conductance quantization have been observed in nanoscopic channels created by either electrostatic gating or by methods that change the geometry of the sample, such as mechanical or chemical etching. While the former electrostatic approach showed promising results with well defined 29. However, the conductance quatization in such devices based on intercalated graphene was reported to manifest itself in the form of kinks11. Well-defined conductance plateaus could not be observed because of the roughness of the heterostructure’s edges and the planar structure itself (the latter resulting from the intrinsic dielectric behavior of the hBN films). These problems were partially overcome by fabricating NCs from exfoliated graphene on hydrophobic silicon oxide substrates with the use of hexamethyldisilazane (HMDS)13. This method led to a substantial increase of the charge mobility which also remained high for a long period of time (~96 h). Quantized conductance at zero magnetic field was also observed in refs13, but only in the form of kinks, suggesting that the edge definition and roughness control was not sufficiently high. In this contribution we propose a novel cryo-etching method theat enables us to overcome the above mentioned problems and fabricate nanoconstrictions with both very high charge carrier mobility and unprecedented quality of the structure edges.On the other hand, encapsulation of graphene between lattice-matched hBN allowed for the fabrication of reproducible high mobility devices14, and generate samples with a high aspect ratio and cleaning15 in nanometric-size structures16. The extension of the cryo-etching technique to graphene allowed us to create NCs with very low sidewall roughness, as proved by atomic force microscopy (AFM) measurements. AFM micrographs were employed to assess the profile of the sample edges, that were later used as input in numerical simulations. We found an excellent agreement between the measured and calculated electrical conductivity and a good correspondence to the theoretical prediction.In this work we present the fabrication method and characterization of NCs on quasi-2D encapsulated graphene where a cryo-etching technique, commonly applied for bulk three-dimensional materials, has been used to achieve an unprecedented control of the edge-definition. This technique was already successfully implemented in silicon-based devices, where it was possible to control and define low-roughness sidewalls, observe the absence of sidewall scalloping10. To the best of our knowledge, this is the first time that a cryo-etching method is successfully used for the definition of graphene nanostructures.We focus the attention on a hBN/graphene/hBN constriction of a few hundreds of width. The constrictions were defined using the innovative cryo-etching process in graphene-based structures in the third aligned EBL step  is colored in blue. A standard 4–probe configuration to perform the electronic characterization at low-temperatures is sketched in the figure, where a pseudo-dc (13) current of 5 nA was injected/collected from the outer contacts while the voltage drop was measured by an in-phase lock-in preamplifier closer to the constriction (the contacts are colored yellow for clarity). The result of a typical measurement at T = 3.1K is depicted in Fig. e2/h is displayed as a function of the normalized back-gate voltage G = 1/R. In our sample the hole-side region (ΔVg < 0V) is always better resolved than the electron one (ΔVg > 0V), where the ballistic behaviour starts at higher back-gate voltage due to the residual charge density. For this reason, in the main text we restrict our discussion to the hole-side  measured at T = 3.1K (red line) and the conductance obtained from our tight-binding simulations (blue line) with the same edge roughness obtained from the AFM measurements . Figure see Fig. .Figure 3lm is larger than the GNC length L = 206 nm, transport is ballistic. We have estimated from the carrier mobility of our GNC that lm > 1 μm  showing a linear dependence of WkFt is the transmission parameter, being t = 1 for the ideal ballistic transport.In the low-temperature regime, when the elastic mean free path WkF above a threshold value 21, while the experimental conductance increases monotonically because temperature is not low enough to reveal this phenomenon. From the normalized gate voltage ΔVg we can obtain the carrier density n and therefore the Fermi wavenumber n0 ~ 3.3 × 1010 cm−2 experimentally, and accordingly WkF could not be tuned below a threshold value t is estimated from the linear fit of the conductance when t ~ 0.9. This value is close to the fully transmitted carrier regime t = 1, in contrast to the estimation t~0.6 given in ref.10 for a graphene NC with a comparable width W = 230 nm that was not defined by cryo-etching. For the electron-side  and the dimensionless transconductance dG/d(WkF) (blue line) versus WkF are shown in Fig. WkF, corresponding to equally-spaced minima in the transconductance. The quantization of G is also very clear after reverting the direction of the current , where the curves have been horizontally shifted by a factor of 2.5WkF for clarity. The presence of the plateaus is clear and they are noticeably visible below T ~ 10K. They start to smear out at higher temperatures until they are completely washed out at T = 25K. Such a temperature dependence of G can be better studied by inspecting the dimensionless transconductance as presented in Fig. WkF decreases by increasing temperature and finally disappears above T = 15K. A similar threshold temperature for the vanishing of the conductance quantization was very recently found in bilayer graphene constrictions23. This behavior differs markedly from other non-desired effects in diffusive regime, such as localized charge carriers, that disappear at higher temperature or other effects that appear also in ballistic graphene quantum point contacts as Fabry-Pérot oscillations24.A closer inspection of the conductance t~0.9 and the size quantization is clearly manifesting itself as a ladder of several 2e2/h-spaced plateaus of conductance at temperatures up to T = 10K, confirming the high quality of the samples. On the other hand, our fabrication method also proves to be scalable. Nanoconstrictions are the simplest model systems which can be viewed as building blocks for more sophisticated devices. We argue therefore that the proposed cryo-etching technique paves the way for the fabrication of more complex graphene-based nanostructured prototypical devices with truly ballistic transport of high-mobility carriers.In summary, we have proposed a novel implementation of the cryo-etching method, which we used for fabrication of high quality hBN-encapsulated graphene nanoconstrictions. The main advantage of the method is an unprecedented control of the edge definition and reduced roughness. The latter enabled us to fabricate high-mobility graphene nanoconstrictions with well defined, sharp and extraordinarily smooth edges. These systems have been characterized by the standard AFM imaging techniques and then the obtained data were used in large scale transport simulations. Results of such modelling agree very well with our experimental low-temperature measurements and suggest that the transport in the system is almost fully ballistic. In particular, both the predicted and measured values of the transmission parameter are as high as 2, P = 1100 mTorr) for 3 minutes for the exfoliation of large graphene flakes. This treatment was not necessary for hBN exfoliation. Graphite and hBN crystals deposited on the tape were attached to the silicon oxide substrate and subsequently heated to 100 °C for 2 minutes. Finally the tape is gently removed and graphene and hBN flakes are identified by optical microscope then by Raman spectroscopy.The fabrication process started from the exfoliation of graphene and hBN on 290 nm silicon oxide thermally grown on a 4 inch Si wafer. Graphene flakes were obtained from natural graphite crystals  and hBN flakes were obtained from hBN crystals (HQ graphene). Graphite crystals were mechanically exfoliated with Magic Scotch Tape and hBN crystals were exfoliated with Ultron Silicone-Free tape B . Wafers were cleaned previously with acetone followed by 2-propanol. Wafers were treated with a oxygen plasma cleaner process  with output power 100 mW and attenuated down to 10 mW with a spot size of 1 μm. A diffraction grating of 600 g/mm was used to provide a frequency shift resolution of 2 cm−1  polymer (12% in anisole) and spin coated on a PDMS thick layer . PDMS was treated before in a oxygen plasma for 3 minutes . Areas free of impurities and bubbles in the graphene heterostructures were selected by inspecting with Raman spectrometer.hBN/graphene/hBN heterostructures were obtained by dry transfer technique, similar to the one reported by Pizzocchero A bar was defined on the graphene heterostructure with electron beam lithography (EBL), using polymethylmethacrylate (PMMA) as a mask. A standard cleaning process and a rapid thermal annealing was performed at 350 °C in Ar atmosphere for 15 minutes to remove eventual small non-visible bubbles and the PMMA remnant. The next steps were a second EBL for the contacts definition and an evaporation of Cr/Au = 5/45 nm with electron beam evaporator. Finally, a self-aligned EBL was performed to define the nanoconstriction mask. The concentration of PMMA in chlorobenzene used depends on the fabrication step: 4% for the mask of the first etching and contacts definition, 2% for the constriction definition.side contacts is obtained by a dry etching processing in induced coupled plasma (Plasma Pro Cobra 100) with SF6 atmosphere (40 sccm), P = 6 mTorr, P = 75 W at 20 °C. We found a typical etching rate of 2–3 nm/s.The etching for the 6 (10/40 sccm) atmosphere at P = 6 mtorr for 18 s, P = 75 W. The use of cryo temperatures and Ar allows us to obtain GNCs with very low roughness as shown in the SI. Ar gas, instead of the more common O2 gas for a cryoecthing recipe, reduces the possibility of passivation to a minimum. The etching rate of the cryoecthing recipe is 2 nm/s. A polymethylmethacrylate (PMMA) was employed as a mask on this step.Nanoconstrictions were defined by cryo-etching process with a third EBL step, which was performed at −110 °C in a controlled Ar/SF26.The AFM measurements of the graphene NC were performed with a Nanotech AFM instrument controlled by Dulcinea system, operating in contact mode and equipped with silicon cantilevers. The images and line profiles were analyzed by Igor Pro and WSxM softwareπ electrons, i〉 is the atomic orbital of the i-th carbon atom27. The corresponding orbital energy level is set as the origin of energy without losing generality. Here tij stands for the hopping energy parameter between orbitals of the i-th and j-th carbon atoms and has been set to be constant between nearest-neighbor atoms  and zero otherwise. Such approximation provides reliable results near the K and K' points of the Brillouin zone, as already reported in ref.29.The electronic properties of graphene close to Dirac point can be accurately described by a tight-binding Hamiltonian for 31 and electron-electron32 interactions in our calculations, we consider electrons in the fully coherent regime, hence with ballistic motion through the whole device. Combining the quantum transmitting boundary method, based on a finite element approximation33, and an effective transfer matrix method adapted for graphene , the wave function in the whole sample and the transmission coefficient τn(E) for each mode n at an energy E is calculated. These modes, also known as channels or subbands, arise from the transverse quantization due to the lateral confinement at the leads35. According to the Buttiker-Landauer formalism35, at very low temperature the electrical conductance is proportional to the transmission coefficient at the Fermi energy EFn runs over the transverse modes. The factor of 2 accounts for the spin degeneracy whereas the valleys are considered explicitly in our tight-binding calculation of the transmission coefficient τn. As the NC becomes wider, the number of transverse modes for a given energy increases and so does the conductance. But interestingly, we found that the main features are essentially the same provided that the conductance is plotted against WkF, where kF is the Fermi wavenumber and W is the NC width. This has an important practical consequence, namely we can extrapolate results to much larger systems than the ones fabricated experimentally and otherwise computationally very expensive (or even impossible) to simulate.Neglecting electron-phononSuplemen tary infrormation file


Graphene is promising for developing soft and flexible electronic skin. However, technologies for graphene processing is still at an early stage, which limits the applications of graphene in advanced electronics. Laser processing technologies permits mask-free and chemical-free patterning of graphene, revealing the potential for developing graphene-based electronics. In this minireview, we overviewed and summarized the recent progresses of laser enabled graphene-based electronic skins. Two typical strategies, laser reduction of graphene oxide (GO) and laser induced graphene (LIG) on polyimide (PI), have been introduced toward the fabrication of graphene electronic skins. The advancement of laser processing technology would push forward the rapid progress of graphene electronic skin. As an ultrathin carbon material, graphene that features high conductivity, flexibility, transparency, bio-compatibility, and mechanical robustness have revealed great potential for developing soft and flexible electronics, especially, electronic skins  is able to trigger the deoxygenation of GO through the photochemical way  Based on LRGO or LIG, various graphene-based electronic skins have been developed. Taking advantage of the laser direct writing technologies, the properties of graphene-based electronic skin can be tuned by laser power, scanning paths, and scanning speeds. The resulted porous and patterned graphene is helpful for design of graphene-based electronic skin. In this section, we will briefly summarize some typical applications of LRGO and LIG in electronic skins.via laser direct writing technologies, which can detect the wet tip by the distribution of ΔZ/Z0. Moreover, the response and recovery time can be tailored by the OCGs contents of LRGO (Guo et al., An et al. fabricated all-graphene based non-contact moisture-responsive electronic skin matrix (An et al., via single-step and selective laser writing (An et al., An et al. produced LRGO-ZnO composites-based UV detectors Wang et al. fabricated strain sensors based on the self-locked overlapping LRGO sheets (Wang et al., −1 in the range from 0 to 50 kPa (Tian et al., Tian et al. developed graphene-based resistive pressure sensor with a sensitivity of 0.96 kPaTemperature response is another function of skin (Harada et al., Tao et al. reported an LIG-based intelligent artificial throat (Tao et al., Here, we have summarized two promising protocols for preparation and processing of graphene, LRGO and LIG. Taking advantage of the programmable processing manner of laser technologies, mask-free and chemical free patterning of graphene can be realized, revealing great potential for developing graphene-based electronic skins. The processing efficiency of laser fabrication is actually the key of large-scale applications. And the processing efficiency remains to be improved by spatial light modulator. Besides, the further trend of laser fabrication of graphene-based electronic skin can be integrated with various functional devices and/or reducing the device size. We believe that continued efforts in laser fabrication of graphene would push forward the rapid progress of this field and lead to breakthrough in both fundamental investigations and practical applications.All authors listed have made a substantial, direct and intellectual contribution to the work, and approved it for publication.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.