It has been suggested that the research priorities of those funding and performing research in transplantation may differ from those of end service users such as patients, carers and healthcare professionals involved in day-to-day care. The Kidney Transplant Priority Setting Partnership (PSP) was established with the aim of involving all stakeholders in prioritising future research in the field.The PSP methodology is as outlined by the James Lind Alliance. An initial survey collected unanswered research questions from patients, carers and clinicians. Duplicate and out-of-scope topics were excluded and the existing literature searched to identify topics answered by current evidence. An interim prioritisation survey asked patients and professionals to score the importance of the remaining questions to create a ranked long-list. These were considered at a final consensus workshop using a modified nominal group technique to agree a final top ten.The initial survey identified 497 questions from 183 respondents, covering all aspects of transplantation from assessment through to long-term follow-up. These were grouped into 90 unanswered “indicative” questions. The interim prioritisation survey received 256 responses , resulting in a ranked list of 25 questions that were considered during the final workshop. Participants agreed a top ten priorities for future research that included optimisation of immunosuppression , prevention of sensitisation and transplanting the sensitised patient, management of antibody-mediated rejection, long-term risks to live donors, methods of organ preservation, induction of tolerance and bioengineering of organs. There was evidence that patient and carer involvement had a significant impact on shaping the final priorities.The final list of priorities relates to all stages of the transplant process, including access to transplantation, living donation, organ preservation, post-transplant care and management of the failing transplant. This list of priorities will provide an invaluable resource for researchers and funders to direct future activity. Kidney transplantation is arguably the most successful treatment for end-stage kidney failure in suitable patients, with evidence that demonstrates cost effectiveness, improved survival and improved quality of life in comparison with patients remaining on dialysis ,2. Over Despite the success of kidney transplantation there are still challenges. The limited donor pool means that access to transplantation is not universal, with a median waiting time of 1,022 days for adult patients in the United Kingdom resulting in a waiting list of around 5,600 patients at any one time . FurtherGiven these challenges, it is perhaps not surprising that the field of kidney transplantation has a very active research community. The research agenda has typically been set by individual researchers or industry, with over one third of randomised controlled trials in transplantation receiving industry funding . It has Increasing recognition of a potential mismatch between the priorities of end service users and researchers/funders has led to a drive towards involving healthcare professionals, patients and carers in projects identifying and prioritising topics for research. This approach has been championed by the James Lind Alliance in the UK, a not-for-profit organisation now a part of the National Institute for Health Research (NIHR) Evaluation, Trials and Studies Coordinating Centre (NETSCC). These “Priority Setting Partnerships” (PSPs) have been successful in a number of areas of medicine, and have led to successful funding of many of the research questions identified –14.The aims of the present study were (i) to identify unanswered research questions in the field of kidney transplantation from end service users  and (ii) to prioritise these questions according to the needs of these groups, for use in future decision making by funders and researchers.The Kidney Transplant Priority Setting Partnership followed the methodology described in detail in the James Lind Alliance (JLA) guidebook . In keepNational patient and professional organisations and charities involved in kidney transplantation were contacted about the project and invited to contribute to a steering group. This group included representation from the Centre for Evidence in Transplantation (CET), British Transplantation Society (BTS), Renal Association (RA), British Renal Society (BRS), Kidney Research UK (KRUK), the National Kidney Federation (NKF) and the British Kidney Patient Association (BKPA). The group was chaired by an experienced advisor from the JLA (LM). The steering group developed the protocol for the project and was involved in all stages of its management. It included transplant surgeons, nephrologists, transplant recipients, living donors and carers. Additional partner organisations were invited to take part in the process by involving their members in the surveys and helping to promote the process. A full list of partner organisations is included in the Supporting Information .The steering group also defined the scope of the project. This incorporated all stages of the transplant process, including access to the waiting list and pre-transplant assessment, the transplant procedure itself, post-transplant care in the short and long-term, management of the failed transplant and issues surrounding retransplantation and living-donor transplantation. Scope included both adult and paediatric patients and their carers and clinicians. In order to maintain the focus of the process, it excluded management of end-stage kidney failure other than transplantation, donor selection and management (other than living donors) and issues specific to combined organ transplants.In order to identify potential research questions, an online survey was created to collect possible questions, along with the demographic details of the respondents. The survey was open-ended, simply asking “What unanswered questions about kidney transplantation and living donation would you like to see answered by research?” with space for up to three questions to be submitted. The survey was piloted by members of partner organisations and the wording refined according to feedback. It was also made available in paper format to improve access. The paper version included the same instructions and questions with the same wording as the online version, and was made available on request. The survey was open to responses between October and December 2014, and promoted via the steering group, partner organisations and other interested individuals. Methods of dissemination included websites, blogs, social media, society/organisation e-mailings and print newsletters distribution of flyers at conferences and events and display of posters and leaflets in transplant centres. The survey was open to all transplant recipients and those on the transplant waiting list, their carers, live kidney donors and professionals involved in the care of kidney transplant recipients in the UK. As the purpose was to collect as many potential research questions as possible, multiple submissions from the same respondent were allowed.The steering group also identified two recent previous surveys from the BTS and KRUK to which respondents were asked to submit potential research questions. Questions from these surveys that fell within the scope of the PSP were also included, although demographic information were not available.The raw submissions were imported into a custom designed MySQL database. Responses were reviewed by two researchers and those that were out of scope (as defined above), or that could not be translated into an answerable research question, were identified. These questions were reviewed by the entire steering group and only excluded if all members agreed.The remaining questions were grouped into similar themes using a pre-defined taxonomy to form a set of “indicative” research questions that covered the scope of all questions submitted. These indicative questions were expressed in the PICO  format as far as possible, although many questions were broad and all four parameters were not defined. Classification and grouping was initially performed by two researchers, with the results discussed in detail by the entire steering group to agree the final indicative questions.www.transplantlibrary.com), which includes all randomised controlled trials and systematic reviews  published in the field of solid organ transplantation between 1970 and present, identified from searches of MEDLINE the Cochrane Library and hand searches of conference proceedings. The purpose of the literature review was to identify any of the questions that were considered adequately answered by the existing literature. In order for a question to be considered answered, an existing up-to-date systematic review with a clear conclusion had to be identified. Questions with no available review, outdated reviews or with an existing review that expressed uncertainty in its conclusions  were considered unanswered. Questions considered answered were discussed in detail by the steering group prior to exclusion from the remainder of the process. A full description of the strategy and search terms used to identify existing reviews is provided in the Supporting Information (Two experienced systematic reviewers reviewed the transplant literature for each of the remaining indicative uncertainties in order to assess the extent of the existing evidence. The primary sources for this review were the Cochrane Library and the Transplant Library (ormation .In order to make a more manageable prioritisation survey (based upon previous JLA experience), remaining indicative questions submitted by three or more individuals to the initial survey were brought forward for prioritisation. A second online survey was designed and piloted in which respondents were asked to rate each remaining question on a five-point Likert scale from “Not at all important” to “Extremely important”. Following an initial pilot, a glossary of terms was also developed to help non-professional respondents understand some of the medical terminology used in the questions. Demographic characteristics of respondents were also collected, including age, sex, geographical region, ethnicity and role. The second survey was open from October to December 2015, and was promoted in a similar way to the initial survey. All respondents to the initial survey were contacted to participate in prioritisation, although this survey was also open to individuals who had not previously participated in the process. Only one response per participant was allowed.Responses to the prioritisation survey were collated and the Likert scale coded numerically from 1  to 5 (Extremely important). The overall mean score as well as the mean score for patients, donors and professionals were calculated for each question. Results were reviewed by the steering group, and the decision was made to take the top 25 ranked questions overall through to the final workshop.A final one-day workshop was held in London in February 2016. The aim of the workshop was to agree a top-ten list of prioritised questions for future research. Professionals , patients and donors from partner organisations were invited to attend and contribute via contact details submitted to the two surveys, as well as organisation mailing lists, social media and websites. Participants were selected with the aim of broad representation of all involved groups and organisations. We initially planned to include around 25 participants in the final workshop, based upon optimal numbers for interaction during previous JLA PSPs, as well as budget and space constraints. Due to illness and unexpected work commitments, 20 individuals eventually participated.The workshop took the form of a modified nominal group process facilitated by experienced JLA advisors. Participants were asked to rank the remaining 25 questions prior to attending the workshop, and in an initial small group session these responses were discussed to identify any agreement in the top and bottom three priorities. In a second small group session the groups were asked to rank the uncertainties based upon this discussion. Groups were balanced to ensure equal professional and non-professional involvement and the facilitators encouraged all participants to take part and voice their opinions. Results of this ranking process from each small group were fed back to the meeting as a whole, with agreement in the top and bottom ranked questions highlighted. A further small group round (with different group composition) took place to revise ranking based upon this feedback. In the final whole group session, the results of the small group discussions were used to suggest a top-ten ranking, and discussion took place as to whether items should be removed or inserted into the top ten. Where there was disagreement, all participants were asked to vote in order to reach a decision. The results of the interim prioritisation survey  were made available on request throughout the meeting to help inform debate and decision making. At the end of the meeting, a final top-ten questions were agreed as priorities for future research.The initial survey received 440 potential research questions from 183 respondents. Responses were from a mixture of professionals (36.1%), patients (37.7%), carers (2.2%) and live donors (21.9%), although some donors also identified themselves as carers for a transplant recipient. Full demographic details of respondents are described in Submitted questions covered the breadth of kidney transplantation, and were categorised as relating to recipient assessment, recipient education, access to the waiting list, organ allocation, management of highly sensitised recipients, organ preservation and reconditioning, live donor transplantation, non-directed donation, tissue typing and immunology, ABO and HLA incompatible transplantation, surgical technique and intra-operative management, post-transplant complications, acute and chronic rejection, recurrent disease, psychosocial outcomes, diet and lifestyle, management of the failing transplant, immunosuppression and tolerance, paediatric and adolescent transplantation and organ bioengineering.The flow of questions through the PSP process is outlined in The interim prioritisation survey received 256 responses from a mixture of patients (30.5%), carers (4.3%), donors (10.9%) and professionals (54.3%). Full demographic details of those responding are described in There was evidence of a difference in priorities between patients, donors and professionals. Of the 25 top-ranked questions, there was a difference in rankings of greater than 5 places between patients and professionals for 16, between donors and professionals for 18 and between patients and donors for 17. Whilst all groups prioritised questions regarding improving long-term transplant outcomes, patients tended to prioritise questions about immunosuppression (including side effects), organ preservation and equity of access. Professionals prioritised questions about assessment of patient and organ suitability and management of antibody mediated rejection. Donors prioritised questions regarding assessment of organ suitability and promotion of living donation. The questions taken to the final workshop represented a mixture of those prioritised by all three groups.Twenty participants took part in the final workshop, representing patients (7), donors (4) and professionals (9). During the day, it was decided that two of the questions had some degree of overlap (regarding organ preservation and conditioning) and the group agreed to merge them together. The top ten research priorities agreed are listed in Of particular note was the desire of the participants in the final workshop to include realistic questions achievable in the short term (for example those relating to the management of immunosuppression) as well as questions that seem much further away from reality such as the development of bioengineered organs and induction of tolerance. The most highly prioritised question from the interim survey (“What is the best strategy to prolong the life of the transplant kidney?”) was felt by the group to be too generic and covered by many of the more specific questions under consideration, and so was not included in the final top ten.A number of questions considered during the process were submitted by non-professionals, and would not have been considered without their involvement. Of the 90 indicative questions 41 (45.5%) were submitted by professionals alone and 14 (15.6%) were submitted by non-professionals alone; the remainder were submitted by both groups. Four questions submitted by patients alone were taken through to the prioritisation stage. Of the final top ten questions, six were originally submitted by both patients and professionals, and four by professionals alone.The final top ten reflected the mixed priorities of all groups. Of the ten, five appeared in the patient top ten during the prioritisation survey, four in the professional top ten, and two in the donor top ten. Four of the final ten were ranked more than five places higher by patients than professionals, and four were ranked more than five places higher by professionals.www.transplantpsp.org/kidney) and the JLA website (http://www.jla.nihr.ac.uk). They were also disseminated to all partner organisations and participants involved in the process, many of whom are involved in or fund transplant research. The James Lind Alliance is part of the National Institute for Health Research (NIHR), one of the largest funders of health research in the UK. The results of the Kidney Transplant PSP have been discussed with NIHR representatives in detail with the aim of taking forward priorities for future specific funding calls.The final list of priorities, as well as all research questions identified, have been made available on the internet through both the PSP website , and the methodology used fulfils many of the criteria defined for good practice in priority setting [The JLA process followed has now been used to identify research priorities in over 35 areas of medicine . The final top ten included questions ranked highly by all groups during the prioritisation process, with an equal mixture of those ranked highly by professionals and non-professionals. It is likely, therefore, that patient involvement played an important role in the shaping of the final prioritised list.A recent systematic review identified four existing publications outlining research priorities with a scope including kidney transplantation . Of thesThe current process may under-represent certain groups affected by transplantation. In particular, very few responses were received from children and adolescents despite partnership with children’s renal charities and the British Association for Paediatric Nephrology. However, many respondents were parents of affected children or nephrologists involved in the treatment of these patients, and questions regarding child and adolescent transplantation were considered during the final workshop. The other patients under-represented in the current process are those from black, Asian and minority ethnic (BAME) groups. These groups made up around 9% of the responses to the initial survey, and 5% of those to the prioritization survey, yet represent around one quarter of the patients on the UK transplant waiting list. BAME patients have significantly higher waiting times to transplantation in the UK, and are less likely to donate . QuestioA further limitation of the current process is the relatively small number of participants in the final workshop. A group size of around 25 participants was determined to provide optimal interaction based upon experience from previous JLA PSPs, and within the budget limitations of the project. Unfortunately, due to illness and unforeseen work commitments the final number of participants was reduced to 20. Despite this, the final group had fair and balanced representation from all stakeholder groups including patients, donors and clinicians. Furthermore, discussions during the final workshop were informed by the rankings of all groups during the prioritisation survey, meaning that the final decision making was influenced by a broader group than just those involved in the workshop.Whilst the prioritised results of this PSP are most relevant to the UK healthcare setting, it is likely that the long-list of potential research questions has international relevance. The review process to check whether questions were truly unanswered by existing literature included evidence from all international healthcare settings, and so whilst it is conceivable that priorities may differ, the unanswered questions are likely to remain the same. This notion is supported by comparison of questions submitted to the current process and those submitted to previous prioritisation processes in other healthcare settings, with significant overlap seen despite differences in priority . One cavPriority setting should not be seen as a one-time exercise, and the priorities set in this process will require future re-evaluation to ensure continuing relevant or to identify new areas of important uncertainty . As yet,The Kidney Transplant PSP has provided an invaluable resource of prioritized, unanswered research questions to help in the design of future research studies. By increasing awareness of these topics, we hope to divert research effort and funding towards the design and implementation of high quality studies, including collaborative randomised controlled trials, with the goal of improving access to transplantation and the long-term outcomes for both donors and recipients.S1 File(DOCX)Click here for additional data file.S2 File(DOCX)Click here for additional data file.S3 File(DOCX)Click here for additional data file.


The humidity sensor consists of an optimally designed porous top electrode, a functional polymer humidity sensitive layer, a bottom electrode, and a glass substrate. The porous top electrode is designed to increase the contact area between the sensing layer and water vapor, leading to high sensitivity and quick response time. The functional polymer mixed with TiO2 microparticles shows excellent hysteresis under a wide humidity-sensing range with good long-term stability. The results show that as the relative humidity ranges from 10% RH to 90% RH, the proposed humidity sensor achieves a high sensitivity of 0.85 pF/% RH and a fast response time of less than 35 s. Furthermore, the sensor shows an ultra-low hysteresis of 0.95% RH at 60% RH, a good temperature dependence, and a stable capacitance value with a maximum of 0.17% RH drift during 120 h of continuous test.In this study, a high-sensitivity and low-hysteresis porous metal–insulator–metal-type capacitive humidity sensor is investigated using a functional polymer mixed with TiO Humidity sensors have been widely used in our daily lives and have become increasingly important in different applications such as meteorology, agriculture, smart homes, medical equipment, and biotechnology ,2,3,4. VIn capacitive humidity sensors, the material of the humidity-sensing layer is one of the most important components. Many types of materials, such as electrolytes ,14, cera2 microparticles. The porous top electrode increases the contact area between the functional polymer sensing layer and the environment, resulting in high sensitivity and fast response time. A functional polymer is proposed by mixing an organic polymer with TiO2 ceramic-based microparticles to achieve ultra-low hysteresis and enhance the humidity-sensing range. The humidity characteristics of the sensor have been tested in various relative humidity conditions. The use of a well-designed porous top electrode and a functional polymer mixed with TiO2 microparticles can improve the properties of the humidity sensor; thus, high sensitivity, low hysteresis, fast response time, and wide humidity-sensing range can be realized.The current paper proposes a high-sensitivity and low-hysteresis metal–insulator–metal (MIM) capacitive humidity sensor using a well-designed porous top electrode and a functional polymer mixed with TiO2 microparticles is proposed for the humidity-sensing layer; it exhibits low hysteresis and good linearity to humidity. The proposed functional polymer is composed of pyromellitic dianhydride (PMDA)–oxydianiline (ODA), which is formed from the polyamic acid precursor of PMDA and ODA with mixed TiO2 microparticles to form a composite material in a weight ratio of 1:1.5, which can fully mix together and good for the water vapor absorption and desorption to realize a high sensitivity and low hysteresis. The average grain size of the TiO2 microparticles is less than 0.1 µm; they are of the rutile type with a dielectric constant of 3.9. Titanium dioxide is a very useful additive, which can improve the hysteresis behavior and humidity-sensing range of the polymer for humidity detection.The porous MIM-type capacitive humidity sensor, having a size of 4 mm × 5 mm, consists of a glass substrate, a bottom electrode, a functional polymer film as a sensing layer, and a top electrode with holes. 2/N2H2 plasma descum step. (e) The polymer is etched using CF4/O2 in a BMR inductively coupled plasma (ICP) asher with a chamber temperature of 81 °C and ICP power of 900 W for 3 min. Some TiO2 residue remains after this etching process. (f) A TiO2 residue removal method was previously proposed by our team [2/N2H2 plasma descum step. (i) A 1000/1000/3000 Å-thick Ti/Pt/Au metal layer is formed by e-beam evaporation, which is used as the top electrode. (j) Finally, a lift-off process is used to create the top electrode on the patterned photoresist layer.The substrate used in the fabrication is a 6 in. glass wafer. The fabrication process of the porous MIM-type capacitive humidity sensor is shown in our team . We founThe fabricated porous MIM-type capacitive humidity sensors are shown in pp; the relative humidity (RH) is used to fit experimental results. The chamber fluctuations in terms of temperature and humidity are ±0.3 °C and ±2.5% RH, respectively. First, we fix the sensors on the measurement board and place it into the humidity-generating chamber. Then, we use coaxial lines, which have low online losses, to connect the measurement board to the LCR meter through a hole on the side wall of the chamber using a good sealant. The varying capacitances can be recorded in real time on the computer through a USB connection with the LCR meter. Before the measurement process, the fabricated humidity sensors were dried and stored in a desiccator to maintain the initial absorbed moisture level close to zero. The chamber humidity was increased from 10% RH to 90% RH and then decreased back to 10% RH in steps of 10% RH; the measurements were taken at 30 min intervals to ensure full sorption/desorption of water vapor.C of the MIM capacitive humidity sensor is expressed as2 microparticles, A is the effective sensing area of the humidity sensor, and d is the thickness of the sensing layer. The permittivity of the polymer changes proportionally with the high dipole moments of water molecules. Therefore, this humidity change is directly detected by measuring the changes in the capacitance. The relative permittivity of the polymers in room conditions is approximately 5, while that for pure water is far greater (around 80). When water vapor is absorbed by polymers, the apparent permittivity value will increase, resulting in a linear increase in capacitance with relative humidity.Capacitive humidity sensors respond to humidity variations by varying their dielectric permittivity, and this variation is directly proportional to the ambient vapor changes. The ideal capacitance D) and spaces between the adjacent holes (L). The sensors show linear outputs with high sensitivity using the functional polymer mixed with TiO2 microparticles. The sensitivity S of the humidity sensors can be expressed asC90 and C10 denote the capacitance obtained at 90% RH and 10% RH, respectively. The 90 and 10 values are the highest and lowest RH values in the variation range, respectively. The sensitivity of the humidity sensor with different hole diameters (20 µm to 100 µm) is shown in 2 ceramic-based microparticles. The role of the TiO2 microparticles can be explained using an ionic conduction model [2 microparticles to form hydroxyl groups. When more water is further adsorbed, each water molecule is hydrogen-bonded to two hydroxyls; then, a liquid-like layer of hydrogen-bonded water molecules is formed, in which each water molecule is only singly bonded to a hydroxyl group. This process could effectively suppress the water clusters in the polymer, resulting in low hysteresis.Hysteresis is a critical drawback of capacitive humidity sensors. It may cause deformation of the polymer owing to water clusters and consequently influence the sensor performance. To reduce the hysteresis, a functional polymer is proposed by mixing an organic polymer with TiOon model . The watH of 0.95% RH at 60% RH, which is calculated byCD60 and CA60 are the capacitance values measured at 60% RH in the desorption and absorption process, respectively. 2 microparticles reduces the hysteresis value.The capacitance variation with the humidity is measured to investigate the hysteresis behavior of the humidity sensor, as shown in The response time is verified by the capacitance variation of the humidity sensor when the ambient humidity is abruptly changed from room conditions to 90% RH. The experimental setup was constructed as follows. The chamber was kept at 90% RH steadily. The humidity sensors were put into the 90% RH chamber at room humidity level through the hole in the chamber. The LCR meter was connected to the humidity sensor throughout the entire process, and it measured the response time at the 90% RH point of the final steady-state capacitance value after an abrupt capacitance change. The response times of the same humidity sensor at three different temperatures  were measured. To determine whether the temperature influences the sensitivity of the humidity sensor, the capacitance changes at three different temperatures  are measured. 2 microparticles. The magnitude of the drift of sensor capacitance is converted into the apparent changes in relative humidity, D, which is calculated by [The long-term stability is tested to investigate the practical value of the humidity sensor. The sensors are placed in an ambient chamber for 120 h at 10% RH, 50% RH, and 90% RH. lated by (4)D=C(m2, organic polymer without TiO2, and the other referenced sensors. The proposed humidity sensor, which employs a functional polymer mixed with TiO2 microparticles, realizes high sensitivity, low hysteresis, fast response time, and wide humidity-sensing range.2 microparticles and a porous top electrode structure was designed to improve the performance of MIM-type capacitive humidity sensors. This work demonstrated a high sensitivity of 0.85 pF/% RH and a fast response time of less than 35 s, which can be achieved by the hole structure on the top electrode. Furthermore, this research achieved an ultra-low hysteresis of 0.95% RH and a wide humidity-sensing range from 10% RH to 90% RH, which can be realized by the functional polymer mixed with TiO2 microparticles. Finally, a good temperature-independent and stable capacitance value with a maximum of 0.17% RH drift was shown to be sufficient for use in a reliable humidity sensor for various applications.A novel humidity-sensitive layer composed of a functional polymer mixed with TiO


In this work, the work function (WF) of graphenes, which are used as electronic devices, has been designed and evaluated by using the first-principle approach. Different states of graphene were considered, such as surface modification, doping, and defects. Firstly, WF strongly depends on the width of pristine graphene. A bigger width leads to a smaller WF. In addition, the effects of hydroxyls, defects, and positions of hydroxyls and defects are of concern. The WF of the graphene which is modified with hydroxyls is bigger than that of the pristine graphene. Moreover, the WF value increases with the number of hydroxyls. Positions of the hydroxyls and defects that deviated from the center have limited influence on the WF, whereas the effect of the position in the center is substantial. Lastly, B, N, Al, Si, and P are chosen as the doping elements. The n-type graphene doped with N and P atoms results in a huge decline in the WF, whereas the p-type graphene doped with B and Al atoms causes a great increase in the WF. However, the doping of Al in graphene is difficult, whereas the doping of B and N is easier. These discoveries will provide heavy support for the production of graphene-based devices. As a material that possesses a variety of excellent performances, graphene –3 has beGraphene WF measured via experiment is approximately at 4.2 to 4.8 eV , 13. The3 solution to adjust the WF  in uniform electron gas. Both GGA and LDA have been used for the calculations in two-dimensional materials. Lebègue et al. found that the band structure of two-dimensional materials obtained using either LDA or GGA is very similar [The generalized gradient approximation (GGA) and local density approximation (LDA) are the exchange–correlation functionals commonly used in quantum mechanics calculations. They are described in Eqs.  and 2)::2):1\doc similar . At the  similar , 34.−6 eV, and the MAX force is 0.03 eV/Å.As for the WF, the previous scanning probe-based studies had shown that the WF is measured as 4.6 eV, such as with graphite . GeneralV0) and the Fermi level (Ef), as shown in Eq.  is the energy of pristine GNRs, E+ d)(GNRs  is the energy of doped GNRs, d is the doping atom, n is the number, and EC and Ed are the chemical potentials determined for carbon and doping atoms.where The formation energy can be used to evaluate whether the feasibility of using atoms for doping is good or not. The smaller the formation energy is, the easier the doping becomes. Figure The WF of graphene in different states, such as surface modification, doping, and defects, are investigated in this study. Basically, the WF decreases as graphene width increases. For the hydroxyl modification, the WF is large when the number of hydroxyls increases. Furthermore, when the distribution of hydroxyls is intensive, the WF is also increased. The defect would decrease the graphene WF, which does not depend on the positions. The p-type doping with B and Al would lead the WF to increase; however, the increased amount is determined by the dopants. The n-type doping with N and P reduces WF greatly. These discoveries will provide a theoretical support in controlling graphene and further improving the design of graphene-based devices.


Recently, a reproducible and scalable chemical method for fabrication of smooth graphene nanogrids has been reported which addresses the challenges of graphene nanoribbons (GNR). These nanogrids have been found to be capable of attomolar detection of biomolecules in field effect transistor (FET) mode. However, for detection of sub-femtomolar concentrations of target molecule in complex mixtures with reasonable accuracy, it is not sufficient to only explore the steady state sensitivities, but is also necessary to investigate the flicker noise which dominates at frequencies below 100 kHz. This low frequency noise is dependent on the exposure time of the graphene layer in the buffer solution and concentration of charged impurities at the surface. In this paper, the functionalization strategy of graphene nanogrids has been optimized with respect to concentration and incubation time of the cross linker for an enhancement in signal to noise ratio (SNR). It has been interestingly observed that as the sensitivity and noise power change at different rates with the functionalization parameters, SNR does not vary monotonically but is maximum corresponding to a particular parameter. The optimized parameter has improved the SNR by 50% which has enabled a detection of 0.05 fM Hep-B virus molecules with a sensitivity of around 30% and a standard deviation within 3%. Further, the SNR enhancement has resulted in improvement of quantification accuracy by five times and selectivity by two orders of magnitude. Though graphene is intrinsically a zero band gap material, its band gap and carrier concentration can be tailored to a few eV by applying external electric field or by surface adsorption of chemical elements. This feature makes graphene a flexible material for the development of superior electronic devices [Graphene is a planar single sheet of sp devices ,2,3. Suc devices . In this devices .Nanostructures in graphene are in the form of nanoribbons, fabricated by either lithographic patterning of graphene sheets or by chemical processes. The former technique usually yields rough edges with dangling bonds and defects . Such inTo date, most of the studies on graphene noise have been conducted on mechanically exfoliated single layer and bilayer devices ,17,18,19This paper makes the first attempt to enhance the SNR in graphene nanosensors operating in FET mode by controlling the functionalization protocol. For this purpose, graphene nanogrids FET immunosensor has been developed following a similar methodology reported earlier . This had) and 100 nm length (l). Secondly, bilayer graphene has been deposited on nanoporous silicon oxide substrate by electrophoretic deposition (EPD) method. For EPD of graphene, interdigited metal electrodes have been fabricated with high temperature silver paste by screen printing method which has been next cured at 750 °C for 1 min. This has been followed by evaporation of gold metal. The prepared colloidal solution of graphene has been pipetted onto the substrate. Then the electrodes have been connected with two probes of function generator and a sinusoidal voltage (peak to peak 19.5 V) has been applied for 60 s. The graphene deposited substrate has been heated at 75 °C for 2 min. This step increases the adhesion between graphene and the substrate. The aforesaid fabrication results in a nanogrid structure with long and narrow graphene strips alternating with series combination of short and narrow strips on planar regions and within pores.For fabrication of graphene nanogrid structure, firstly nanoporous silicon oxide (NPSO) substrate has been developed by anodic etching of p-type <100> silicon wafers of 10–20 Ω·cm resistivity in a double pond electrochemical bath for 30 min under a constant current source with an electrolyte mixture of hydrofluoric acid (HF) (48 wt%) and dimethyl sulfoxide (DMSO) in the ratio of 1:9 by volume. The structure has been thermally oxidized using a dry-wet-dry sequence in an oxidation furnace for 1 h at 900 °C to obtain pores with 30 nm diameter  the graphene nanogrid structure has been treated with 25%, 10% and 2.5% glutaraldehyde aqueous solutions (procured from Sigma Aldrich) for 2 h, 4 h and 24 h. After treatment, each sample has been rinsed with de-ionized water and for every parameter, optical density (O.D.) measurement has been carried out to estimate the covalent binding of graphene with glutaraldehyde. Then the graphene structure has been incubated with anti Hep-B antibody for 1 h followed by washing with phosphate buffer saline (PBS). This process activates the negatively charged carboxylic groups of graphene and improves the covalent binding of antibodies. After antibody immobilization the nanogrid structure has been incubated with different concentration of Hep-B solution for 10 min. Hep-B solution has been prepared in the range of 50 aM to 10 pM by standard process of serial dilutions . The binGSV) has been applied. The sensing signals of the device have been recorded by monitoring the change in the drain current (DSI) for a given drain-source voltage (DSV) and GSV, when the device has been exposed to different concentrations of Hep-B solution. Further, Hep-C has been used as the non-specific antigen and complex mixtures of Hep-B and Hep-C has been prepared in buffer for testing the selectivity of the sensors. The buffer used for DSI measurement is 20 mM PBS. All the measurements have been carried out on five sets of sensors and the mean and standard deviation have been plotted.Electrical measurements of graphene nanogrid FETs have been performed using a Keithley 6487 instrument  at room temperature. To facilitate electrical measurement, two ends of interdigited electrodes have been used as drain and source. A polydimethylsiloxane (PDMS) container has been glued to the surface in the region between the source and drain to avoid fluctuations due to positioning of the solution droplet. Gate has been realized using a separate platinum electrode which has been inserted into the solution in the PDMS container, through which variable gate to source voltage ) of the transient fluctuations has been computed in MATLAB using Equations (1)–(3):k = 0, 1, …, N/2), t = Sampling interval. Finally according to Parseval’s theorem, Φ(f) has been multiplied by the sampling interval Δt and N to obtain power spectral density function, S(f). Data with equidistant time scale has been recorded and subdivided into sets, containing multiples of 2n data points. For S(f) calculation, spectra consisting of 800 Fast Fourier Transform (FFT) points in frequency have been averaged for 200 s.The fluctuations of Optical density (O.D.) measurements have been performed in a UV-VIS spectrophotometer  to estimate the number of HIgG antibodies attached to the glutaraldehyde treated graphene nanogrid structure. For estimating the binding density of HIgG antibody, HRP conjugated HIgG has been used along with a standard coloring reagent solution. The preparation details of the coloring reagent have been reported elsewhere . The optFor non-destructive examination of number of layers of graphene, Raman spectroscopy has been performed with a laser excitation wavelength of 532 nm and 50× objective using a LabRAM HR Evolution device . The laser power at sample has been maintained below 0.1 mW to avoid laser induced heating and sample damage. The spectrum has been accumulated over 10 s exposure for two sets. The intensity of G band has been used to determine the number of layers of graphene.−1 and a symmetric 2D band at ~2680 cm−1 with an intensity ratio of around 1.4. This confirms the presence of bilayer thickness. The antibody binding has been optimized by tailoring the glutaraldehyde concentration and treatment time for a constant incubation temperature. The concentration of glutaraldehyde solution has been selected as 2.5%, 10% and 25% for three different treatment times . It can be observed from 2 groups of antibodies. The O.D. also tends to saturate after 24 h, probably because the maximum possible binding has already taken place. However, it is observed from The Raman spectrum of RGO shown in DSI has been measured in presence of PBS for different GSV as shown in DSV of 1 V. It has been observed that for negative GSV, the resistance is lower than that for positive GSV which indicates that the graphene layer is p-type. The glutaraldehyde treated RGO surface is negatively charged and the antibody molecules are positively charged. Hep-B virus being negatively charged [DSI increases with increasing concentration of the antigen for negative GSV. Further, due to increase in the carrier concentration, Dirac point shift towards right. For positive GSV, changes in DSI with Hep-B concentration are insignificant which may be attributed to the poor electrophoretic capture on the surface. charged , IDS incDS after Hep-B capture. It is observed from GSV of −30 V. Thus, the variation of sensitivity with different incubation parameters of glutaraldehyde is shown in GSV of −30 V. It is observed from DSI readings is a vital parameter for improving the sensing performance. Moreover, it is observed from The sensitivity has been computed as the maximum fractional change in IS(f)DS/I2) is shown in S(f)DS/I2 increases with incubation time and concentration. Thus, SNR has been estimated as the ratio of sensitivity to DSS/I2 and shown in It has been reported that the low frequency noise in electrical resistance of bilayer graphene is strongly connected to its band structure and carrier density and that the noise increases with increasing carrier density . This haDS-VGSI characteristics in presence of low Hep-B concentration for the optimized and unoptimized sensors. It is observed that the optimized sensor can quantify 0.05 fM antigen within a range of 0.05–0.055 fM which is an error of 10%. On the other hand, the unoptimized sensor detects it within a range of 0.05–0.075 fM which is an error of 50%. The impact of SNR enhancement on selectivity has also been estimated by exposing the optimized and un-optimized sensors to different complex mixtures. From the DSI-GSV characteristics shown in DSI curve for 1 fM Hep-B is significantly reproducible even in the presence of 1 nM Hep-C, whereas in the unoptimized sensor, it shifts significantly if the Hep-C concentration exceeds 10 pM. This indicates that high SNR improves the selectivity by two orders of magnitude. This may be attributed to the increased noise in the unoptimized sensor which probably causes a significant drift in DSI due to non-specific adsorption. Hence the SNR enhancement has led to the realization of a reliable and ultrasensitive graphene nanogrid sensor with a five times and 100 times improvement in quantification accuracy and selectivity respectively.The impact of SNR on the sensitivity characteristics is shown in This paper makes the first attempt to enhance the SNR in graphene nanosensors operating in FET mode by controlling the functionalization protocol. The proposed work is extremely relevant, especially for bilayer graphene nanostructures since the low frequency noise increases with increasing carrier density. The incubation time and the glutaraldehyde concentration have been optimized in graphene nanogrid FET sensor for maximizing the SNR. It has been observed that an incubation time of 4 h with 25% glutaraldehyde concentration results in low level detection of Hep-B virus down to 0.05 fM concentration with an appreciable sensitivity of around 30% and a standard deviation within 3%. Further, the optimized sensor has resulted in improvement of quantification accuracy by five times and selectivity by two orders of magnitude. Hence the proposed methodology for SNR optimization can be extended to different configuration of nanostructured graphene biosensors.


Fairness is a critical component of defensible assessment. Candidates should perform according to ability without influence from background characteristics such as ethnicity or sex. However, performance differs by candidate background in many assessment environments. Many potential causes of such differences exist, and examinations must be routinely analysed to ensure they do not present inappropriate progression barriers for any candidate group. By analysing the individual questions of an examination through techniques such as Differential Item Functioning (DIF), we can test whether a subset of unfair questions explains group-level differences. Such items can then be revised or removed.We used DIF to investigate fairness for 13,694 candidates sitting a major international summative postgraduate examination in internal medicine. We compared (a) ethnically white UK graduates against ethnically non-white UK graduates and (b) male UK graduates against female UK graduates. DIF was used to test 2773 questions across 14 sittings.Across 2773 questions eight (0.29%) showed notable DIF after correcting for multiple comparisons: seven medium effects and one large effect. Blinded analysis of these questions by a panel of clinician assessors identified no plausible explanations for the differences. These questions were removed from the question bank and we present them here to share knowledge of questions with DIF. These questions did not significantly impact the overall performance of the cohort. Group-level differences in performance between the groups we studied in this examination cannot be explained by a subset of unfair questions.DIF helps explore fairness in assessment at the question level. This is especially important in high-stakes assessment where a small number of unfair questions may adversely impact the passing rates of some groups. However, very few questions exhibited notable DIF so differences in passing rates for the groups we studied cannot be explained by unfairness at the question level.The online version of this article (10.1186/s12909-018-1143-0) contains supplementary material, which is available to authorized users. Promoting fairness in assessment is an important priority. Entrance to medical school and progression as a doctor should be determined by ability, not ethnicity or sex . Recognid = 0.42) effects whereby ethnically non-white UK graduates underperformed relative to white UK graduates in assessments at both undergraduate and postgraduate levels. Nor is it merely an assessment issue – questionnaires evaluating the postgraduate working experience find ethnically non-white trainees experience lower levels of satisfaction , a high stakes postgraduate assessment in internal medicine and we compare (a) ethnically white UK graduates against ethnically non-white UK graduates and (b) male UK graduates against female UK graduates. DIF was used to test 2773 questions across 14 sittings, each initially comprising two three hour papers of 100 questions each. We report the results of the DIF analysis alongside a review of questions exhibiting DIF.All analyses were carried out on different diets (forms) of the same high stakes postgraduate examination. The examination is a criterion-referenced written examination comprised of 200 questions, sat in two separate 3 hour papers of 100 questions each, designed to assess core clinical knowledge. Blueprinting, item content and standard setting are all developed and determined by panels of experts with relevant clinical backgrounds.Fourteen sittings were included in this analysis: three each for 2011, 2012, 2013 and 2014, and two for 2015. In total, there were 47,048 candidate entries across the fourteen sittings, which included candidates who had not qualified in the UK. Candidates had been invited to provide information on their protected characteristics, which included sex, whether their primary medical qualification was from the UK or not and whether they were ethnically white or ethnically non-white, as part of the routine application process for the examinations. 6047 candidates failed to provide information on any or all of these questions, and a further 27,307 sittings were excluded due to the candidate not having a UK PMQ. This left 13,694 candidate sittings – all UK graduates – in the present study with graduates who were resitting being included as separate entries for the purpose of the present study. Consequently, some candidates had multiple entries in the analysis, with each entry being a single attempt at the examination, sat during different diets. No candidate had multiple entries for any individual diet. Candidates routinely provided consent for anonymised analysis of examination results, and approval was granted by the MRCP(UK) board for the work to be undertaken.R [difR [lordif package [All analyses were carried out in R . For steR [difR  or for a package . We ran  package . The DIFp < .05 would, with 5546 tests, require p < .05/5546 = 9.01 × 10− 6 for significance after adjusting for multiple testing.For each question we calculated DIF using the logistic regression method  which ca2 [We report the number of questions identified as exhibiting DIF. We further investigated any questions with either a medium or large effect size as measured by Nagelkerke’s R2 . All eig− 6.Table Table Following this analysis, the eight questions were reviewed by an expert panel comprised of ten clinicians of diverse backgrounds  to evaluate the possible causes of DIF. The analysis was blinded. Reviewers were not able to consult with other panel members, and knew only that DIF was present – not the type or magnitude. No reviewer was able to suggest any cogent explanation for the DIF for any item.This paper presents the first evaluation of DIF in the context of a large postgraduate medical examination, the MRCP(UK). In this dataset, which relates to a single high stakes postgraduate knowledge based assessment of single best answer MCQ design, and is comprised of an extremely large sample size of test takers and questions, DIF was detected using simple software and statistical tools. Importantly however the analysis shows most such effects are negligible and only a very small number of questions exhibit DIF of a medium or large effect size. Furthermore, no clear cause of the observed DIF can be derived from analysis of independent blinded panel review.This research shows that methods to evaluate DIF successfully used in other fields can be applied to medical education , 17. DifWe believe that this analytical strategy is simple, advantageous and suggests that DIF evaluation can be one of a range of measures to test fairness. Routine analysis will identify the – apparently rare – cases of notable DIF and so promote fairness at the borderline of pass/fail decisions. Connecting such psychometric analyses with expertise in question writing allows for the development of better training in question-writing, promotes awareness of the possibility of bias in written assessment, and allows for the development of a body of knowledge around questions most likely to produce bias. The notable DIF questions have all been withdrawn from the question bank and publicised amongst question writers, even though the reason for their differential functioning is unclear. As more items are identified in future analyses it may be that common structural or content issues will emerge as explanations.The study had some limitations. Replications on novel datasets are required to evaluate how common DIF effects are in other areas of assessment. As some candidates are prone to resitting, and therefore will have appeared in multiple datasets, exploring whether resitting candidates exhibit DIF compared to non-resitters of similar ability levels would be useful in extending this analysis. Furthermore, evaluation at the undergraduate level would be very helpful given the importance of differential attainment in application to medical school and performance at medical school. While we were able to evaluate possible reasons for question bias, we consulted experts, rather than novices, and work with candidates applying to sit assessment would be a useful comparator to identify why questions might (or might not) be considered biased. Exploring other features of the items – such as length, item type, language complexity and so on – may be a useful avenue of exploration. Furthermore, Identifying and publicising problem questions could be a powerful tool for advancing fairness if other organisations repeated this analysis and pooled the results. Importantly, the causes of DIF were unexplained and whether they are false positives or due to some yet unstudied factor remains open. Relatedly, this method was only one of a family of DIF procedures, and comparing it against other techniques (e.g. Mantel-Haenszel) may yield slightly different results.This research has provided a model for the monitoring and removal of questions with DIF in high stakes assessment. By making such analyses routine, we can promote fairness at the question level and ensure that assessment is based solely on candidate ability. Questions showing DIF were rare, and there was usually little clear relationship of the substantive content of the questions to the DIF found, suggesting that in most cases the DIF was of little meaning in relation to the overall performance of the candidates.Our expert review was blinded to the nature or direction of DIF, but the reviewers knew that DIF was present. A more exacting test, perhaps to be carried out in the future, would be to give examiners a balanced set of questions and say that a third showed DIF evidence of sex differences, a third showed DIF evidence of ethnicity differences, and a third showed no evidence of DIF by sex or ethnicity, and ask them to judge which question was in each type. Our feeling is that examiners probably would be unable to do that task correctly, suggesting that there are few obvious features about these questions which are related to the presence of DIF.Overall it seems highly unlikely that any candidates were disadvantaged by the small effects that were found. The differential attainment of candidates in the various groups does however remain, and remains unexplained, but cannot be attributed to differential item functioning in relation to sex or ethnicity of particular questions in this multiple choice assessment across the range of diets analysed.Additional file 1:High resolution images of the plots contained in the paper. (ZIP 2058 kb)


This paper presents a passive wireless humidity sensor for concrete monitoring. After discussing the transmission of electromagnetic wave in concrete, a novel architecture of wireless humidity sensor, based on Ultra-High Frequency (UHF) Radio Frequency Identification (RFID) technology, is proposed for low-power application. The humidity sensor utilizes the top metal layer to form the interdigitated electrodes, which were then filled with polyimide as the humidity sensing layer. The sensor interface converts the humidity capacitance into a digital signal in the frequency domain. A two-stage rectifier adopts a dynamic bias-voltage generator to boost the effective gate-source voltage of the switches in differential-drive architecture. The clock generator employs a novel structure to reduce the internal voltage swing. The measurement results show that our proposed wireless humidity can achieve a high linearity with a normalized sensitivity of 0.55% %RH at 20 °C. Despite the high losses of concrete, the proposed wireless humidity sensor achieves reliable communication performances in passive mode. The maximum operating distance is 0.52 m when the proposed wireless sensor is embedded into the concrete at the depth of 8 cm. The measured results are highly consistent with the results measured by traditional methods. Structural Health Monitoring (SHM) systems are automated tools, aimed at rapidly identifying the onset of structural damage and at tracking the condition of structures during forced or natural excitation . CurrentThanks to fast and easy installation, wireless sensors are gaining a growing interest. Most of the wireless sensors for SHM are based on Wireless Sensor Networks (WSN), which are battery-powered and permit long-range operating ,9. HowevHumidity is one of the parameters considered as a critical factor in the progress of cement maturity by influencing the stability, the transformation of hydrates, and strength development . The resThere are various kinds of RFID-based humidity sensors. The simplest kind is the chipless RFID temperature sensor, which requires no Integrated Circuits (ICs) and transmits sensor data by changing the radar cross section of the RFID antenna . The chaThis paper presents a novel wireless humidity sensor for SHM. To our knowledge, this is the first work to measure the concrete humidity based on UHF RFID technology. The rest of the paper is organized as follows. Since concrete has distinct electromagnetic properties at different humidity conditions, the total power loss for electromagnetic waves penetrating concrete are analyzed through the 1 MHz to 1 GHz frequency range for various humidity conditions (at depth of 0.2 m), i.e., 0.5%, 2.5%, 5.5%, and 13%. The matlab simulation results are shown in The aim of the proposed RFID sensor is to perform humidity measurement inside the concrete, thus the type of the antenna should be taken into consideration. tP is calculated from the Friis transmission equation [rE is the effective isotropic radiation power of a reader, aG is the tag antenna gain, rη is the RF-to-DC power conversion efficiency of the rectifier, λ is the wavelength of the electromagnetic wave, and d is the communication distance. From Equation (1), the communication distance d can be expressed as:The theoretical practicable operating power of an RFID tag equation :(1)Pt=EtP and higher rη are critical for the design of UHF RFID tag, for rE is limited by regional regulations (4 W is the maximum transmitted power) and aG is roughly determined by the allowable antenna area (1.64 for the λ/2 dipole antenna).Hence, in order to achieve longer communication distance, lower RV for the subsequent circuitry. Once the output of the rectifier reaches the operating voltage, the Power-On-Reset (POR) block generates a reset signal stR for the temperature sensor. The clock generator provides a reference clock CLK for the sensor interface. Because the sensor interface and the clock generator should operate under a stable supply voltage DDV, a regulator block is employed to stabilize the output voltage of the rectifier. This architecture does not include the demodulator and the baseband blocks in the traditional RFID tag, which means that this wireless humidity sensor will operate without any addressing as long as the sensor receives enough energy from the RFID reader [Because concrete is a high-loss material for electromagnetic wave transmission, this paper proposes a novel architecture to lower the overall power dissipation of wireless sensor for longer operating distance. D reader .L is the length of metal electrodes, S is the width of each electrode, and W is the distance between adjacent electrodes. The thickness of the polyimide layer is H, which is generally larger than metal thickness h. For a N finger array sensor, the total sensor capacitance hC can be expressed as [L is the length of metal electrodes, h is the thickness of metal layer, W is the distance between adjacent electrodes, and wetε represents the dielectric constant of the polyimide film with absorbed water. Considering the factors including sensor capacitance, chip area sensitivity, etc., this work chooses N = 40, L = 200 µm, W = 2.5 µm, S = 2.5 µm, h = 1 µm, and H = 2 µm.Inspired by the reported CMOS humidity sensor designs ,28,29,30essed as :(3)Ch=Noscf which is then countered by a 10-bit counter to output the corresponding digital output oB. For a standard ring oscillator, assuming an equal rise and fall time for the different stages respectively, the oscillating frequency of the ring oscillator oscf can be expressed as follows:dt is the delay time of the loop, lI is the current flowing through the inverter, lC is the equivalent load capacitance of the loop, and mV is the swing range of the output voltage which mostly equals the supply voltage DDV. Because lC is mainly determined by the capacitance hC of humidity sensor, oscf is a sensor-controlled frequency and oB is the corresponding digital output of humidity sensor.The capacitive humidity sensor acts as a capacitor when it works with the sensor interface. The traditional interface starts with a capacitance-to-voltage converter, which is then followed by a voltage-to-digital converter ,33. Thisoscf versus temperature on different process corners are shown in oscf achieves good linearity with temperature and the simulated worst case variation across corners is around ±9%.The simulation results of the proposed frequency outP is the average DC output power generated at the output of the rectifier and inP is the average RF power available at the input of the rectifier. From a circuit-level point of view, rη is mainly degraded due to the forward drop of the switch diodes or transistors [N11–22 and PMOS transistors MP11–22 form the differential-drive switch. In order to achieve a flat rη curve, the bias-voltage VN1,2 and VP1,2 are employed to boost the gate-source voltage of NMOS switch and PMOS switch, respectively [SR is added to block the AC component of VN1,2 and VP1,2. In CMOS process, SR could be replaced by a PMOS transistor that operates in the cut-off region to avoid the large silicon area.A popular performance metric of a rectifier is its power conversion efficiency which is defined as:nsistors . Differensistors ,36,37, Fectively . The larU,L) is superimposed on the bias voltages BiasN2 and BiasP2 to provide the shifted voltages GateN2 and GateP2 to the gate of NMOS and PMOS switches, respectively.P0–MP1 and MN0–MN2 compose a start-up block, which is added as a precautionary measure to ensure bias in the desired state. The transistors MP2–MP4 and MN3–MN6 compose a reference generator block to provide a reference voltage REFV of 0.26 V which is compensated by temperature and supply voltage. The transistors MP5–MP10 and MN7–MN9 compose a regulator to generate a stable voltage DDV of 1.0 V for other circuits. DDV − outV characteristic at room temperature of 25 °C. The circuit starts working properly with DDV = 0.47 V. In the supply voltage range from 0.47 V to 2 V, an average reference voltage of 266.5 mV is generated. In this measured DDV range, the output voltage changes at most by 1.8 mV, thus leading to a line sensitivity of 0.441%/V.Due to the large variation of the output voltage of rectifier, a reference circuit with small supply voltage coefficient is necessary to generate a stable reference voltage. The traditional way to generate stable 1.25 V reference voltage is using a bandgap reference circuit . However1–M6 consist of an N stage current-starved inverter, the transistor M7–M9 and M10–M12 consist the current mirrors of inverter. Compared with the conventional structure, the extra transistors MH1, MH2, ML1, and ML2 are employed to reduce the voltage swing [The clock generator always employs ring oscillator architecture based on current-starved inverters. The output voltage of traditional current-starved inverters is close to the supply voltage and ground, which improves the output range while increasing the power consumption. As is shown in ge swing .Microstrip antenna is designed by including a ground plane structure, which has a natural anti-metal advantage compared to the dipole antenna. The length of rectangular microstrip patch antenna length is approximately equal to half of its electrical length, which is not suitable for the miniaturization of tags. As shown in 2 and the diameter of the hole is 0.2 cm.A protection device is necessary before the sensor tag is embedded into concrete, so that the sensor tag is not impaired by hydration heat arising from grouted concrete and not soaked directly in water of concrete. The transmission signal of sensor tag is sent out by electromagnetic wave, hence it is important to pay attention to wireless transmission impedance matching. Based on civil engineering techniques, this study proposes a protective high permeability acrylic package box. In order to keep the sensor in contact with the environment fully, 16 holes were punched on the side and 20 holes were punched at the bottom of the proposed package box. 2 and was equipped with this antenna on FR4 substrate by using flip chip. Then the sensor tag was packaged with the package box for concrete monitoring as shown in rη curve of the proposed rectifier is shown in rη curve. When input power is 13 dBm, the two curves both reach the optimal point 69%. As for the input power range whose rη is above 60%, the proposed rectifier and the conventional rectifier achieve −19 dBm and −7 dBm range, respectively. The measured wetε results in this error. d, the distance of the RFID reader placed above the concrete is H, the incidence angle between the reader and the sensor is θ. The photo of the test site is shown in θ and power transmission is shown in θ is 90°, the power transmission efficiency is 85%. When θ is larger than 75°, the power transmission efficiency is nearly 0%. Hence, in order to achieve the best test results, the incidence angle should be as vertical as possible. When we set θ = 90° and d = 8 cm, we measure the maximum communication distance of RFID reader. A calibrated humidity sensor SHT75 is embedded together with the proposed wireless humidity sensor to monitor the concrete humidity. For each measurement, the reader was instructed to perform 1000 attempts to read the sensor data from the wireless humidity sensor. When the success ratio remains above 80%, the communication distance is considered to be reliable. As shown in We embedded the sensor into the concrete at a depth of 8 cm and then investigated the influence of incidence angle on power transmission. The relationship between the incidence angle This work employs concrete made of normal aggregate  as the sample. The proposed wireless humidity sensor is embedded at a depth of 8 cm inside the concrete sample with the calibrated wired humidity sensor SHT75. The results measured by these two sensors compared with results of the moisture probe are plotted in Humidity monitoring plays an important role in concrete measurement, and thus this work presents a wireless humidity sensor based on UHF RFID technology. Considering the high losses of electromagnetic waves in concrete, a patch antenna is proposed to ensure the sensor tag can work inside of the concrete. The wireless humidity sensor employs a novel architecture and is carefully designed for low power application. The measured results show the proposed sensor tag achieves high humidity linearity with a normalized sensitivity of 0.55% %RH at 20 °C. The maximum operating distance is 0.52 m when the proposed wireless sensor is embedded into the concrete at a depth of 8 cm. The measured results are highly consistent with the results measured by traditional methods. The whole experiment demonstrates that the proposed wireless humidity sensor can provide reliable performance.


Thermal chemical vapour deposition techniques for graphene fabrication, while promising, are thus far limited by resource-consuming and energy-intensive principles. In particular, purified gases and extensive vacuum processing are necessary for creating a highly controlled environment, isolated from ambient air, to enable the growth of graphene films. Here we exploit the ambient-air environment to enable the growth of graphene films, without the need for compressed gases. A renewable natural precursor, soybean oil, is transformed into continuous graphene films, composed of single-to-few layers, in a single step. The enabling parameters for controlled synthesis and tailored properties of the graphene film are discussed, and a mechanism for the ambient-air growth is proposed. Furthermore, the functionality of the graphene is demonstrated through direct utilization as an electrode to realize an effective electrochemical genosensor. Our method is applicable to other types of renewable precursors and may open a new avenue for low-cost synthesis of graphene films. Graphene films are commonly produced by thermal chemical vapour deposition, which is capable of producing high-quality films but still limited by factors such as high cost. Here, the authors report the growth of single-to-few-layer continuous graphene films under ambient-air conditions. Graphene growth occurs by thermal reforming of a natural precursor, soybean oil, in a closed ambient-air environment. Unlike conventional CVD methods or conventional natural precursor methods for growing graphene, the technique does not require any purified gases8The parameters observed to control the quality of graphene include temperature, processing time, precursor, substrate and the ambient-air environment. Nickel acted as a good catalyst for the breakdown of precursor material  into smaller building units that are essential for the synthesis of grapheneTo investigate how the transformation occurred in the process, we have analysed the chemical composition of the annealed soybean oils at different temperatures . During 122 to form water vapour. In particular, water vapour can promote the etching of amorphous carbon deposits on the Ni surfaceAt elevated temperatures, long hydrocarbons in the oil decompose in the presence of OWe have also noticed that a slow cooling can promote excessive carbon segregation from the Ni bulk, which may account for the observed formation of a graphite-like film . AnotherIt is worth mentioning that graphene did not form on other growth substrate materials with significantly lower carbon solubility than Ni, such as the commonly used Cu foil. Moreover, we did not observe graphene formation on graphitic surfaces such as woven carbon cloth . This suThe structural morphology of the graphene film was analysed by transmission electron microscopy TEM; . The disIn addition, selected-area electron diffraction patterns were taken across a typical region of the sample, where a slight rotation between these patterns was observed . The hig2 graphene film grown in the ambient-air process was transferred from the Ni foil substrate to a glass surface, as demonstrated in ID/IG and I2D/IG intensity ratios were taken from four regions R1–R4, as denoted in −1, the graphitic peak (G-band) at ∼1,580 cm−1, and the second-order 2D-band at ∼2,670 cm−1. The D-band is attributed to the finite crystallite size effect and various defects induced in the sp2 carbon materials; the G-band arises from the in-plane vibrational E2g mode of the sp2-hybridized carbon; and the 2D-band is a second-order Raman spectral feature due to the three-dimensional interplanar stacking of hexagonal carbon networksID/IG is 0.15–0.25 and that of I2D/IG is 0.95–1.50, as shown in 2 V−1 s−1 was estimated for the graphene film , sp3 (285.4 eV), nickel carbide (∼282.8 eV) and C–O–C (∼286.5 eV) and O–C=O functional groups . The survey scan of Moreover, this ambient-air process for graphene synthesis was also applicable to Ni foil growth substrates of lower purity. Graphene films of comparable quality were produced with low-purity polycrystalline Ni foils (99%) rather than high-purity foils . Such loThe growth of graphene in an ambient-air environment may initially seem counter-intuitive, as graphene is expected to be destroyed in air at elevated temperatures (above 500 °C). However, we hypothesize that the unique processing conditions promote the controlled synthesis of graphene films in an otherwise destructive environment. Specifically, the thermally dissociated precursor material decomposes in the presence of reactive oxygen species from the ambient-air, leading to the formation of water vapour as a by-product . The watNi foil heat treated in ambient environment without soybean oil, where surface oxidation will be prevalent ;Ni foil heat treated in ambient environment with soybean oil, following procedure as outlined previously for the growth of graphene, where surface oxidation may be prevented .To better understand the growth process and the possible interaction with Ni substrate, we conducted experiments to probe the surface composition of Ni foils following treatments at elevated temperatures. In particular, we investigated the composition of:2, which consequently limited the surface oxidation of Ni at elevated temperatures.Our XPS analyses showed that when the Ni foil was heated in the ambient environment without soybean oil, oxygen was easily identified on the surface (Ni:O ratio of 1:1.83). However, when the Ni foil was heated with soybean oil, the oxygen content was significantly reduced (Ni:O ratio of 2.69:1). These results indicated that the breakdown of soybean oil in the reaction chamber provided a reaction pathway for the consumption of O3, C2H2 and other species, at the ramping stage  was measured to characterize the response of graphene to the surface immobilization of miRNAs. The Rct was observed to increase upon successful immobilization of probe miRNAs on the graphene surface (Rct was observed as the concentration of target miRNAs was increased (Rct by (Rct−R0)/R0, where R0 is the charge-transfer resistance of the reference sample. This increase in ΔRct is attributed to an impeded charge transport at the graphene surface, caused by spatial blocking of the captured target miRNA molecules. In addition, the hybridization between complementary genomic sequences may induce a build-up of negative surface charge, which may repel negatively charged ferricyanide ions and lead to an increase in Rct  technique. The charge-transfer resistance  at physiologically relevant concentrations. This suggests that nonspecific binding at the graphene surface did not interfere with the specific binding events with the target miRNA sequence.The graphene-based sensor also demonstrates selectivity against miRNA sequences that are mismatched by a single RNA base, as shown in  10−14 M . Further 10−14 M . The gra−13 M single-stranded (ss)DNA−13 M ssDNA−12 M  to enable controlled synthesis and tailored properties of the graphene film in the ambient-air process. Further, we propose a mechanism for the growth of graphene in the ambient-air process, based on depth profiling of the as-grown film, analyses of the ambient-air composition in the reaction chamber and reaction pathways for precursor reforming into graphene. The functionality of the graphene films was demonstrated through its direct integration as an electrochemical genosensor, in which sensitive and selective bio-detection was realized. Importantly, the ambient-air synthesis of graphene films from renewable precursors offers numerous advantages and opportunities for future streamlined integration into large-scale production infrastructures and the realization of diverse graphene-enabled technologies.Graphene films demonstrate excellent functional properties and are promising for diverse applications. However, the high cost and complexities associated with graphene production impede its commercial viability. To this end, we present a novel method for the synthesis of graphene films, in an atmospheric-pressure, compressed-gas-free ambient-air environment utilizing safe, low-cost renewable precursors. This ambient-air method offers numerous advantages over conventional thermal CVD techniques for graphene synthesis, which critically rely on resource- and time-consuming procedures . Graphen−1. This was followed by holding at 800 °C for 3 min. After the growth step, the sample was immediately removed from the heating zone to enable a rapid cooling (at approximately 25 °C min−1) to segregate the homogeneous and continuous graphene films. Owing to the evaporation and thermal expansion of the precursor material, a small build-up in pressure within the tube was observed. Throughout the heating stage (200 to 800 °C), atmospheric pressure was maintained in the quartz tube by allowing this build-up of gases to exit via the exhaust of the tube. A controlled gas environment was created in the tube through enabling the circulation of gases produced by precursor evaporation. Following the heating stage, pressure within the quartz tube was observed to be stabilized at atmospheric pressure. No additional gases were introduced into the quartz tube throughout the entire growth process.The growth of graphene was carried out in a thermal CVD furnace  with a quartz tube . Polycrystalline Ni foils  were used as the growth substrate. The experimental schematic is shown in −1 of PMMA  was spin-coated onto the as-grown graphene on Ni foil . The sample was then dried in open air for 12 h. Subsequently, the underlying Ni foil was dissolved in 1 M FeCl3 in 30 min. The PMMA/graphene film then floated to the surface. This was washed several times with deionized (DI) water. Next, the PMMA/graphene was lifted off from the DI water bath and transferred onto a glass substrate. The PMMA was then dissolved with acetone, and the sample was repeatedly washed with DI water. The graphene on glass was then used for subsequent microscopy and electrical characterization.A poly (methyl methacrylate) (PMMA)-assisted transfer of graphene was adopted. Briefly, 46 mg ml2. The XPS spectra were recorded with a Specs SAGE 150 spectroscope with Mg Kα excitation at 1,253.6 eV. Both survey scans and narrow scans of C 1 s and Ni2p3/2 were conducted. The Ni and graphene/Ni surfaces were progressively etched through Ar bombardment to create a depth profile of the material. The TEM images were obtained with a JEOL 2200FS TEM microscope operated at 200 kV.Raman spectroscopy was performed using a Renishaw inVia spectrometer with Ar laser excitation at 514 nm and a probing spot size of about 1 μm2 was used, and optical spectra were recorded in the wavelength range from 300 to 800 nm.Optical images were obtained with an Olympus BX51 optical microscope. Transmittance measurements were obtained using a Varian Cary 5000 ultraviolet–visible spectrophotometer. A graphene area of 4 cm2 was used. Four-point probe measurements were conducted at room temperature.Silver paint was applied to the graphene transferred onto glass. A graphene area of 1 cm2O3 holders, and were heated to required temperatures  at 10 °C min−1 heating rate under air purge gas. Correction/blank runs were carried out for each temperature range with empty reference and sample pans before sample thermal analysis. Evolved Gas Analysis was carried out by coupling the Netzsch system to a Thermostar Pfeiffer Quadrupole Mass Spectometry to determine gases and vapours evolving in the atomic mass range of up to 200 a.m.u. (plotted as mass to charge ratio m/z).The Netzsch STA 449 F1 instrument equipped with S-type DTA sensor was used for simultaneous thermogravimetric/differential thermal analysis of the soybean oil precursor samples. Soybean oil samples were placed in Al2 plasma  to introduce carboxylic functional groups on its surface. The sample was placed flat and 2 cm below the plasma generation zone. The size of each sensing substrate was 2 × 1 cm2. Then, the plasma-actived graphene was treated with 0.05 M N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (EDC) and 0.03 M N-hydroxysulfosuccinimide (NHS) in phosphate-buffered saline  for 15 min. This enabled the formation of active ester intermediates via carbodiimide chemistry. Next, the surface of graphene was washed several times with PBS and DI water to remove excess EDC/NHS. Next, the surface of graphene was washed several times with PBS  and DI water to remove excess EDC and NHS. Then, NH2-conjugated miRNAs  were diluted in PBS to 0.2 μM, and 50 μl was pipetted onto the EDC-treated surface. This was left to incubate overnight in a wet environment and at room temperature. Next, the sensing surface was washed with 0.05% sodium dodecyl sulfonate (Sigma-Aldrich) in 0.04 M hydroxylamine solution (Sigma-Aldrich) to deactivate the remaining carboxylic functional groups and to remove non-specifically bound probe miRNAs. Then, 0.01 M polyethylene glycol (Sigma-Aldrich) was loaded on the sensing surface to block the exposed areas of graphene to reduce further nonspecific binding. Next, the (biomarker) miRNA sequence  was dissolved in human serum  to obtain dynamic concentrations of 1 nM to 0.1 pM, which were pipetted onto the sensing surface. This was left to incubate at 45 °C for 20 min to induce hybridization between the complementary probe and target sequences. Finally, a washing step with PBS/DI water was used to remove remaining non-specifically bounded target miRNAs. To demonstrate sensing specificity, a similar protocol was adopted by replacing the target sequence with a single-base mismatched miRNA sequence . This fully assembled device was then utilized in a three-electrode electrochemical cell for biosensing measurements.The as-grown graphene on Ni foil was treated with a low-temperature O6 in 0.1 M Na2SO4 at room temperature. A three-electrode cell configuration was used. The three-electrode cell used the as-grown graphene on Ni as the working electrode, a Pt wire as the counter electrode, and an Ag/AgCl reference electrode. The EIS measurements were conducted in the frequency range from 500 kHz to 1 kHz, using a BioLogic VSP 300 potentiostat/galvanostat instrument. The charge-transfer resistance (Rct) of the sensing electrode was determined by the diameter of the semi-circle region in the EIS plots. The Rct of the sensor following incubation with the target miRNA was expressed as a percentage of Rct in the reference (blank) case, which was incubated in the human serum medium in the absence of target miRNAs. To evaluate the contribution of nonspecific interactions, the interfering analytes  were diluted in the FeCN6/Na2SO4 electrolyte before the electrochemical measurements. Further, linear regression analysis was utilized to estimate a detection limit for the sensor. From the plot of ΔRct versus concentration, a relation of ΔRct=90.89+6.04 log10 (Concentration [M]) was deduced (R2=0.99) for sensing the target sequence. The limit of quantification was calculated by 10Sy/b, with Sy as the standard deviation of the y-intercept (Sy=7.24) and b as the slope of the linear fit .Publisher's note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.Supplementary Figures, Supplementary Tables, Supplementary Notes and Supplementary References


When used as anode materials in lithium-ion batteries, the composite exhibited good cyclic stability and decent specific capacity of 677 mA·h·g−1 after 50 cycles. CuO NWs can enhance the lithium-ion storage of the composites while the f-graphene effectively resists the volume expansion of the CuO NWs during the galvanostatic charge/discharge cyclic process, and provide a conductive paths for charge transportation. The good electrochemical performance of the synthesized CuO/f-graphene composite suggests great potential of the composite materials for lithium-ion batteries anodes.The copper oxide (CuO) nanowires/functionalized graphene (f-graphene) composite material was successfully composed by a one-pot synthesis method. The f-graphene synthesized through the Birch reduction chemistry method was modified with functional group “–(CH Therefore, they have been widely applied in telephones, personal computers, and electric vehicles ,2,3,4,5.enignity ,7,8,9,10enignity . For inst method . Among tt method ,14. Thest method ,16,17. Ht method ,19. Addit method ,21,22. WRecently, CuO and graphene composites with various morphologies have been fabricated by using different synthetic processes ,25,26,272)5COOH” groups were introduced onto f-graphene sheets via the Birch reduction chemistry method, which function as the nucleation sites for the formation of CuO nanowires (NWs) without adding any surfactants, according to previous literature [In most of these studies, rGO sheets were used. The rGO sheets were obtained by oxidizing graphene into graphene oxide first, and reducing it in the following step. However, the oxidation step will always damage the mircrostructure and molecular structure of graphene, and the reduction process could not completely restore its electrical conductivity behaviour . Here interature . This meterature ,25,28,302)5COOH” groups and the detailed processes were shown as follows [2  was added and reacted for 50 min. The mixed solution was stirred overnight. After the liquid ammonia evaporated completely, the product in the flask was transferred and mixed with hexane, and then washed by NaOH solution (pH = 11) three times to remove impurities. Finally, the CuO/f-graphene composite was dried at 60 °C overnight. The schematic of the synthesis procedure of the CuO/f-graphene composite is depicted in 2, and the pure CuO material was synthesized by the same method without adding graphene.The CuO/f-graphene composite was successfully synthesized via a one-pot chemistry method. The f-graphene was prepared through the Birch reduction chemistry method to yield “– was tested at a heating rate of 10 °C·min−1 in air from room temperature to 800 °C by using a NETZSCH TG-DTA/DSC analyzer . The Raman spectrum was measured on a DXR Raman Microscope  via a 633 nm He-Ne laser.The morphology of CuO NWs were characterized by using the field-emission scanning electron microscope  at 30 kV. Transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) were measured on a JEOL JEM-2100F TEM at 200 kV . The crystalline phases of the composite were studied by an X-ray diffractomer  scanning from 10° to 80° with Cu K−2. The assembly of coin cells was performed in an argon-filled glove box by using CR 2025 coin-type cells with lithium foil counter-electrodes, Celgard 2400 membranes as separators, and 1.0 M LiPF6 in ethyl methyl carbonate (EMC)/ethylene carbonate (EC)/dimethyl carbonate (DMC) (volume ratio 1:1:1) as electrolyte. The galvanostatic charge/discharge performances were measured on a multichannel battery tester  with a voltage range from 0.01 to 3.0 V at room temperature. The cyclic voltammetry (CV) and electrochemical impendence spectroscopy (EIS) measurements were carried out on an electrochemical workstation .The anode electrodes were made up of the CuO/f-graphene composite, polyvinylidene fluoride (PVDF), and conducting acetylene black with a weight ratio of 80:10:10 dissolved in N-methyl-2-pyrrolidinone (NMP) solvent. Then, the slurry was coated on a Cu foil and heated at 120 °C for 12 h in a vacuum drier. The average mass coated on the electrodes is about 1 mg·cm−1 and 1600 cm−1. The former one, named D band, reveals the defect of the C atomic lattice while the latter peak called G band represents the stretching vibration of C atom sp2 hybrid plane. The intensity ratio (D/G ratio) shows an obvious increase after functionalization. The result suggests that the functional groups “–(CH2)5COOH” were successfully attached to the graphene and the sp3 defect centers were introduced [−1 in the Raman spectrum of the CuO/f-graphene composite is in agreement with the Raman signal of the monoclinic CuO, which gives the CuO NWs a priority to react on these defective positions.The Raman spectrum of f-graphene b shows ttroduced ,33. MoreThe SEM, TEM, and HRTEM images of raw graphite, the f-graphene, pure CuO, and the CuO/f-graphene composite are shown in 2 have reacted completely.2O phase and the decomposition of Cu2O into Cu [2O and CuO, respectively [ into Cu ,27,36. Iectively ,37. The From the second cycle to the fourth cycle, the CV curves of the CuO/f-graphene composite have higher extent overlapping than the CV curves of pure CuO and other CuO/graphene composite reported before , suggest−1 with voltage range from 0.01 to 3.0 V. In the first cycle, three voltage plateaus at about 2.0–2.3 V, 1.2–1.5 V, and 0.5–0.8 V are observed. This indicates that during the conversion process, multi-step electrochemical reactions have taken place between CuO and lithium, which correspond to the three cathodic peaks of the CuO/f-graphene composite in the CV curves . It suggests that the introduction of functional groups “–(CH2)5COOH” can increase the specific surface area of graphene to some extent compared with graphite, thus enhancing the capacity of lithium storage. The pure CuO shows a distinct capacity decline from 716 mAh·g−1 to 331 mAh·g−1. Contrast this with the f-graphene and pure CuO, where the initial charge and discharge capacities of the CuO/f-graphene composite are 912 mAh·g−1 and 778 mAh·g−1, respectively. Due to the various irreversible processes mainly including the ineluctable formation of SEI film and electrolyte decomposition, the capacity of the CuO/f-graphene composite has a reasonable loss in the first cycle. After the second cycle, the discharge capacity stabilizes at 677 mAh·g−1 during the whole cyclic process. The initial coulomb efficiency of the CuO/f-graphene composite is 85%, which is much higher than previous reports [2)5COOH” functional groups has increased the interlayer spacing of graphene sheets, and the expanded graphene sheets are highly conducive and leave enough space for the copper oxide to be inserted between the f-graphene sheets, which leads to the structural stability after several galvanostatic charge-discharge cycles. In addition, the “–(CH2)5COOH” groups can provide nucleation sites for the formation of well-dispersed CuO nanocrystals. −1. As we can see, the discharge capacities of the CuO/f-graphene composite are 659, 595, 467, 357, and 244 mAh·g−1, respectively at current densities of 0.1, 0.2, 0.5, 1.0, and 2.0 A·g−1. When the current density is restored to 0.1 A·g−1, the discharge capacity goes back to 572 mAh·g−1, making it clear that the CuO/f-graphene composite has a decent structural stability. On the other hand, the f-graphene exhibits an excellent stability at the same current densities since the specific capacity varies from 438 mAh·g−1 at 0.1 A·g−1 to 177 mAh·g−1 at 2 A·g−1 during the first 25 cycles and recover to 403 mAh·g−1 at 0.1 A·g−1 in the last five cycles. We may safely draw the conclusion that the stability of the CuO/f-graphene composite is attributed to the f-graphene. reports ,26. And  reports ,24,26,29ct), which engenders between the liquid electrolyte and the active materials, is denoted by the medium-frequency semicircle in the EIS [w), is ascribed to lithium diffusion within the electrodes. Apparently, the CuO/f-graphene composite has a smaller semicircle compared with the pure CuO before cycling, which indicates a lower Rct of the CuO/f-graphene composite than that of the pure CuO. Comparing to the pure CuO, the CuO/f-graphene composite has a better electronic conductivity and charge-transfer performance with the addition of conductive f-graphene [Finally, the electrochemical impedance spectroscopy (EIS) was carried out to investigate the kinetics, electric double layers, and diffusion of the electrode reaction process. As depicted in  the EIS . At low graphene .−1 at first cycle at a current density of 100 mA·g−1 and a good electrochemical stability with the capacity of 677 mAh·g−1 after 50 cycles. The introduction of functional groups “–(CH2)5COOH” has increased the interlayer spacing of graphene sheets, and the expanded graphene sheets are still conducive and leave enough space for CuO to be inserted between f-graphene sheets, which leads to the structural stability after galvanostatic charge-discharge cycles. In addition, “–(CH2)5COOH” groups provide nucleation sites for the formation of well-dispersed CuO nanocrystals. Therefore, this method can be a general approach to prepare anode materials for LIBs.In summary, the CuO/f-graphene composite material have been successfully synthesized by a one-pot wet chemistry method. The CuO NWs were well-dispersed in the f-graphene sheets with sizes ranging from 300 nm to 500 nm in length and 10 nm to 20 nm in width. As an anode material in LIBs, the CuO/f-graphene composite displays improved electrochemical performance compared to the pure CuO counterpart. It shows a high capacity of 912 mAh·g