We report flexible piezoresistive strain sensors containing poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), graphene nanoplatelet (GNP), and polydimethylsiloxane (PDMS)-based ternary conductive hybrid nanocomposites as an active sensing layer fabricated using a simple solution-processed technique. The sensors have been fabricated on flexible PDMS substrate which is patterned using emery papers having grit size of 80 and 100. The electrical characterization has been undertaken in PDMS-based flexible devices mounted on smart gloves with structures PEDOT:PSS/GNP/PDMS. The microscopic study of the microstructured PDMS is done using field emission scanning electron microscopy (FESEM). The size of PDMS microstructure based on 80-grit and 100-grit emery papers is found to be in the range of 165-196 and 121-148 mu m, respectively. FTIR peaks at 677, 930, similar to 1000-1110, and 1519 cm(-1) signify the C-S, S-O, Si-O-Si, and C=C stretching, respectively. From X-ray diffraction (XRD), the diffraction peak at 26.60 degrees corresponds to 002 facets of GNP, whereas PEDOT:PSS showed no distinct peaks of PEDOT:PSS film indicating amorphous nature of the polymer. The gauge factor (GF) of the sensor based on 80-grit emery paper is determined to be 601.3 within the strain ranging from 0% to 46%. The sensor shows highly reproducible response over 2100 bending and stretching cycles suggesting long-term durability. Response and recovery time of the fabricated sensor is calculated to be 140 and 155 ms, respectively. The developed smart glove integrated flexible strain sensor is capable to detect human pulse and monitor the real-time human motions, and therefore, it may find a great promise for application in smart wearable electronics and human-machine interface.

Contemporary society heavily depends on power electronic systems, playing a pivotal role in realizing sustainability objectives by mitigating adverse environmental effects like the release of greenhouse gases and the exacerbation of global warming. Wide Bandgap (WBG) power components have the potential to bring about a paradigm shift in energy efficiency as compared to conventional silicon (Si)-based components. Amid various WBG materials, namely Gallium Nitride (GaN) and Silicon Carbide (SiC), GaN and SiC have surfaced as the most promising due to their exceptional performance capabilities. By utilizing WBG-based components, it becomes possible to achieve swifter switching accompanied by reduced energy losses at higher frequencies, thus facilitating the advancement of compact and remarkably efficient power converters. This present evaluative paper delves into the advantages and obstacles linked with SiC and GaN power devices, along with their applications in the realm of power electronics.

In this work, a resistive-type relative humidity sensor using polyvinyl pyrrolidone/multiwalled carbon nanotube (PVP-MWCNT) composite film is reported. The electrical characteristics of the paper-based flexible devices with Cu/MWCNT/PVP structures have been studied. The microscopic analysis of the hybrid nanocomposites is done using field emission scanning electron microscopy. Diameter of the MWCNT is found to be 20–80 nm, whereas the length is determined to be 100–800 nm. Raman spectra at around 1347.73, 1584.03 and 2695.68 cm−1 signify D, G and 2D peaks of MWCNTs, respectively. The humidity sensing behaviour has been studied for this sensor by resistance measurements in the relative humidity (RH) ranging from 36

Smart gloves with their multifunctional sensing capabilities, hold a promising in human-machine interface (HMI) applications. In this work, we present a smart glove based on single-walled carbon nanotubes (SWCNTs) incorporated within a polydimethylsiloxane (PDMS) matrix integrated flexible strain sensor. The flexible strain sensor is designed and fabricated to serve as a crucial sensing component for the smart glove. The integration of SWCNTs with PDMS offers a unique combination of mechanical flexibility and electrical sensitivity, making it an ideal candidate for real-time monitoring and feedback in HMI applications. The fabricated SWCNTs/PDMS strain exhibits a high sensing range, covering up to a strain range of 70%, along with high sensitivity, characterized by a gauge factor (GF) of 73. Additionally, the strain sensor demonstrates excellent linearity, reliability, and durability, enduring repeated loading and unloading for 3000 cycles under a 50% strain. Furthermore, the developed smart glove successfully extends sensing functionality, enabling real time-tasks such as finger motion detection, controlling robotic fingers and can be used in the field of smart wearable electronics and HMI applications.

This paper studies the temperature-dependent electrical transport properties of nickel (Ni) and nickel–chromium (Ni–Cr) sputtered on n-type 4 H-SiC substrate. Barrier inhomogeneities have been found to affect the electrical parameter of the Schottky barrier diode (SBD) from 323 to 423 K temperature range, We have done current–voltage characterization of Ni and Ni–Cr Schottky junctions. The barrier height (ϕ _Bo) , reverse saturation current (I_r) , ideality factor (η ) and series resistance (R_s) were obtained from I–V characteristics of Ni and Ni–Cr and these parameters are observed to be highly dependent on temperature. It has been observed that Ni–Cr contact has exhibited better electrical characteristics as well as thermal sensitivity as compared to Ni. This may be attributed to the smaller number of barrier inhomogeneities at the Ni–Cr/4 H-SiC interface. In the temperature range from 323 to 423 K, Ni and Ni–Cr-based Schottky contacts, Following observation has been noticed (a). Schottky barrier height (SBH) increased from 1.24 to 1.37 eV and 1.15 to 1.45 eV, (b). Ideality factors reduced from 3.76 to 2.61 and 3.20 to 2.53, (c). Series resistance decreased from 10.22 to 3.37 Ω and 2.45 to 1.16 Ω , and (d). Reverse leakage current 524.88× 10^-12 to 79.66× 10^-9 A and 557.32× 10^-12 to 1.51× 10^-9 A respectively. The V–T curves for both SBDs are investigated (for the same temperature range) to calculate their thermal sensitivity (α ) at 1.0× 10^-4 and 5× 10^-10 A, respectively. The V–T curves with linear behavior are used to calculate the thermal sensitivity coefficient (α ) , which was found to be 7.11 to 7.93 mV/K for the Ni–Cr SBD, and 7.1 to 20.01 mV/K for the Ni/4 H-SiC contacts. The sensitivity-current (α -I) characteristics for the Ni/4 H-SiC SBD were found to be a non-linear comparison with Ni–Cr/4 H-SiC SBD, which may be attributed to the presence of a highly resistive and non-uniform coating of Ni at the interface.

This study presents the development of strain sensors using two silicone rubbers (Ecoflex and polydimethylsiloxane) with graphene nanoplatelates (GNP). The polymer and graphene nanoplatelets capitalize on the elasticity of polymer and the electrical conductivity of GNP, making it for enhanced electrical response. This work presents the fabrication, characterization, and performance of both flexible strain sensors, elucidating their mechanical behavior and sensing capabilities by unifying flexibility, conductivity, and responsiveness. Both sensors displayed flexibility and linear change in resistance, highlighting their sensitivity. Comparative analysis revealed the Ecoflex/GNP sensor's higher gauge factor, indicating elevated sensitivity for strain detection. The proposed Ecoflex/GNP and PDMS/GNP-based strain sensors are suitable for wearable electronics applications.

In this work, flexible sensors consisting of silver nanowires (Ag NWs), graphene nanoplatelets (GNP), and polydimethylsiloxane (PDMS) are fabricated using a straightforward, affordable, and simple solution processing technique. The performance of the flexible devices with structure Ag NWs/GNP/PDMS has been studied, in which Ag NWs/GNP-based ternary conductive hybrid nanocomposites are used as acting sensing layers. The diameter of Ag NWs and flake size of GNPs were determined to be 80-160 nm and 30-190 nm, respectively. The Raman peaks of Ag NWs within the composite are appeared at 392.08, 482.12, 543.7, 679.42 and 854.87 cm(-1). The peaks existing at 1317.68, 1565.36 and 2639.75 cm(-1) represent the D, G and 2D bands of GNP, respectively. The gauge factor is determined to be 865 within the strain range of 0-71 %. The response and recovery time of the fabricated sensor are calculated to be 101 and 110 ms, respectively. The sensor exhibits a minimum detectable limit of 0.8 %. The sensor shows a highly reproducible response for more than 1150 bending and stretching cycles suggesting long-term durability which may be attributed to the Ag NWs/GNPs conductive networks for significant strengthening the hybridisation with PDMS. Different human activities, viz. finger bending, stretching, mouse/mobile screen scrolling, swallowing through the throat and drinking are monitored by the fabricated Ag NWs/GNP/PDMS-based flexible strain sensor, indicating promising applications in wearable electronics.

This study presents the development and characterization of a flexible Graphene/PDMS-based strain sensor for human motion detection applications. The sensor is fabricated using chemical vapor deposited (CVD) graphene onto a Polydimethylsiloxane (PDMS) substrate. The proposed sensor offers a promising solution for capturing and quantifying the complex deformations associated with human movements. The strain-induced changes in the graphene’s electrical conductivity are monitored and correlated with the applied mechanical strain. The sensor exhibits excellent sensitivity, repeatability, and linearity, making it suitable for accurate and reliable human motion detection. The proposed strain sensor holds great promise for various human-centric applications. Its integration into wearable devices or clothing could provide real-time monitoring of body movements and posture, enabling applications in sports performance analysis, health monitoring, and rehabilitation.

This study presents the development of strain sensors using two silicone rubbers (Ecoflex and polydimethylsiloxane) with graphene nanoplatelates (GNP). The polymer and graphene nanoplatelets capitalize on the elasticity of polymer and the electrical conductivity of GNP, making it for enhanced electrical response. This work presents the fabrication, characterization, and performance of both flexible strain sensors, elucidating their mechanical behavior and sensing capabilities by unifying flexibility, conductivity, and responsiveness. Both sensors displayed flexibility and linear change in resistance, highlighting their sensitivity. Comparative analysis revealed the Ecoflex/GNP sensor’s higher gauge factor, indicating elevated sensitivity for strain detection. The proposed Ecoflex/GNP and PDMS/GNP-based strain sensors are suitable for wearable electronics applications.

Graphene-based dry electrodes have shown considerable promise in electrophysiological signal monitoring applications by providing a comfortable, irritant-free alternative to traditional wet electrodes. The proposed electrode was fabricated using a spray-coating technique by depositing reduced graphene oxide (rGO) on a polydimethylsiloxane (PDMS) substrate. The rGO/PDMS dry electrodes exhibit the capability to capture and transmit weak bio-electrical signals such as Electrocardiogram (ECGs) and Electromyogram (EMGs) without significant attenuation or distortion. Experimental results show that when compared to conventional wet Ag/AgCl electrodes, the fabricated rGO/PDMS electrodes measure higher-quality ECG signals with improved SNRs while offering similar contact quality and electrode-skin impedance despite being a dry electrode. The fabricated rGO/PDMS electrodes demonstrated excellent performance and applicability making them suitable for use in wearable long-term health monitoring devices.

We report flexible piezo-resistive strain sensors composed of silver nanoparticle (Ag NP), graphene nanoplatelet (GNP), and multi walled carbon nanotube (MWCNT)-based ternary conductive hybrid nanocomposites as an active sensing layer fabricated using a simple solution processing method on flexible polydimethylsiloxane (PDMS) substrates. The electrical characteristics have been studied in PDMS-based flexible devices having three different kinds of structures, namely Ag NPs/MWCNT/PDMS, GNP/PDMS and Ag NPs/GNP/PDMS. The microscopic analysis of the hybrid nanocomposites is undertaken using field emission scanning electron microscopy. The diameter of the CNTs is found to be in the range of 20-40 nm, whereas the length is determined to be 100-800 nm. The average diameter and length of the GNPs are observed to be 30-50 nm and 100-500 nm, respectively. The crystallite size of the silver nanoparticles in the Ag NPs/MWCNT/PDMS and Ag NPs/GNP/PDMS-based nanocomposites is determined to be 22.8 nm and 29.1 nm, respectively. The prepared sample of Ag NPs shows four distinct peaks in the X-ray diffraction pattern, which correspond to the (111), (200), (220), and (311) face-centered cubic (FCC) crystalline planes. Raman spectroscopy is undertaken to study the fundamental physical properties and chemical analysis of the nanocomposites. Ag NPs/GNP/PDMS-based sensors exhibit superior performance in terms of sensitivity, response and recovery time during breathing/unbreathing analysis. The large surface area of the Ag NPs and GNPs promotes uniform distribution of Ag NPs to fill into the porous GNP surface, thereby facilitating high contact area along with better electron transport in the Ag NPs/GNP/PDMS hybrid nanocomposite-based sensors. The gauge factor (GF), response and recovery time of the Ag NPs/GNP/PDMS hybrid nanocomposite-based sensors are determined to be 221, 130 ms and 119 ms, respectively. The ternary conductive nanocomposite-based sensors are free from the drawbacks of binary nanocomposite-based sensors where the high percolation threshold and poor mechanical behaviour lead to the degradation of the device performance.

In this work, we report the fabrication and characterization of a Schottky diode containing a metal–semiconductor Schottky junction. The metal–semiconductor Schottky contact was formed using nickel (Ni) as the metal and silicon carbide (4H-SiC) as the semiconducting material. The metal–semiconductor Schottky diode array was fabricated on 350-μm-thick 4H-SiC (0001) substrates. The Schottky contact was formed using Ni, and a triple layer of Ti/Pt/Au was used for the ohmic contact. Deposition of Ni-Cr alloy on 4H-SiC was carried out to improve the adhesion at the metal–semiconductor interface. Based on the current–voltage (I–V) characteristics, the device output parameter values for turn-on voltage, forward current at 5 V, reverse saturation current, barrier height (φB) and ideality factor (η) were 1 V, 2.57 mA, 652 nA, 0.935 eV and 1.296, respectively. A band diagram is proposed to explain the charge transport phenomena.

In this report, we study the optimal design and simulation of Schottky junction solar cells consisting of cadmium sulfide (CdS) and graphene layer using Silvaco TCAD Atlas software. During device modeling the thickness of the top layer of graphene as an electrode and the middle semiconducting layer of CdS as an active region is taken as 10 and 70 nm, respectively. Polyethylene terephthalate (PET) is used as the flexible substrate for the study. We also report the fabrication of flexible solar cells on PET substrates composed of CdS and graphene synthesized inhouse by solution process. The I-V characteristics have been undertaken in both the simulated and fabricated devices with structure graphene/CdS/PET. Under AM 1.5 G, the fabricated device with the structure graphene/CdS/PET shows an open- circuit voltage (Voc) of 0.163 V, a short circuit current density (Jsc) of 0.00063 A/m2 and a fill factor (FF) of 56.50%. The Ideality factor and reverse saturation current of the device is determined to be 9.6 and 0.063 mu A, respectively.

The multiwalled carbon nanotubes/ polydimethylosiloxane (MWCNT/PDMS) composite based pressure sensor has been widely adopted in wearable health care devices and electronic-skins due to its high flexibility, piezoresistivity, high sensitivity over a broad linear range and biocompatibility. Herein, MWCNT/PDMS composites with different MWCNT contents were fabricated and their mechanical and electrical characteristics were evaluated in detail for each case. The MWCNT/PDMS composite pressure sensors shows high sensitivity (0.02715–0.08283 kPa $^{\text {-1}}$ ) over large pressure sensing range from 0.1 to 100 kPa. In addition, through the cyclic stretching test, the strain-sensing properties of the MWCNT composite shows high reliability over 1000 repetitive cycles. The flexible devices can be used as the wearable electronic skin and successfully mounted on human skin to achieve the capability of physiological stimuli monitoring, i.e., human wrist pulse wave for health care applications. The wide linear working range with high sensitivity of the MWCNT/PDMS pressure sensor makes it a potential choice in flexible electronics such as wearable devices for health care monitoring, soft robotics and E-skin application.

Silicon Carbide (SiC) Schottky diode is simulated using Silvaco TCAD. Five different metals, Aluminum (Al), Platinum (Pt), Palladium (Pd), Nickel (Ni), and Molybdenum (Mo), used for Schottky contact and diode parameters such as ideality factor, barrier height, turn-on voltage is studied. The forward current density and breakdown voltage of the Schottky diode is studied with thickness and doping density of ntype 4H-SiC semiconductor. Doping density varied from 1 x 1014 cm-3 to 9 x 1014 cm-3, and epi-layer thickness varied from 10 mm to 50 mm. By varying doping concentration, thickness, and metal contact, an optimized Schottky diode is obtained for high-speed switching applications. (c) 2021 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the International Conference on Advances in Materials Science, Communication and Microelectronics.

On the 4H-SiC substrate, C-face and Si-face oxide layers have been grown by thermal oxidation process and sputtering. The thermal oxidation temperature dependence of 4H-silicon carbide (SiC) is systematically investigated using capacitance-voltage (C–V) measurements. The oxidation quality and thickness vary according to the temperature and time duration of the thermal oxidation. The layers’ thicknesses are determined by atomic force microscopy (AFM), and the temperature range is between 800°C and 1110 °C. The primary reason to fabricate the Metal-Oxide-Silicon (MOS) capacitor is to know the thermal oxidation process and a working principle. In this paper, we optimize a thermal oxidation process and fabricate the MOS structure. Then we determine the various parameters such as flat band voltage (V f b ), Inversion threshold voltage (V t ), Surface depletion capacitance (C dep ), Oxide capacitance (C ox ), the total capacitance of the device (C o ), doping concentration (N d ), Depletion width (X d ), Maximum depletion width (X dt ) and Interface trap density (D it ). Finally, we analyze and discuss the MOS capacitance.

We report flexible piezoresistive strain sensors containing two different layers of materials such as graphene and graphite, fabricated by a simple spin coating method on flexible polydimethylsiloxane (PDMS) substrates. In-house synthesized graphene and graphite-PDMS nanocomposites are used as active layers into the devices. The microstructure analysis of graphene and graphite-PDMS composites are carried out using scanning electron microscopy (SEM) technique. Small flakes having a thickness of 10-30 nm are clearly seen from the SEM images. Fundamental physical properties of graphene and graphite-PDMS nanocomposites are studied using Raman spectroscopy technique. In the Raman spectra, different bands, i.e. D, G and 2D of graphene, are located at 1340, 1577 and 2690 cm−1, respectively. The characteristic G peak of graphene is raised due to planar vibration of sp2 hybridized carbon. Two-phonon 2D peak determines the carbon stacks present in graphene. Existence of defects in graphene are determined by the D peak. The electrical characteristics are studied in PDMS based flexible devices with two different kind of device structures, viz. Ag/graphene/PDMS and Ag/graphite-PDMS. The gauge factor and sensitivity for the devices containing graphene are determined to be 6.260 and 2.155, whereas those values are found to be 0.906 and 0.051 for graphite-PDMS nanocomposite-based devices, respectively. Graphene based flexible devices are observed to be superior than its graphite-PDMS nanocomposite counterparts. Thus, simple device structure, easy device fabrication, affordable, portable and accessible including reasonably good sensitivity; it finds great potential for the manufacturing of wearable sensors.

This paper presents the fabrication and characterization of spin coated multilayer graphene oxide/p-silicon heterojunction solar cell. Liquid graphene oxide is synthesized from graphite sheets using electrochemical process. XRD confirms the presence of graphene oxide. Surface morphology of spin coated on graphene oxide on silicon wafer was investigated by scanning electron microscopy. The current–voltage characterization has been studied to investigate photovoltaic performance of fabricated solar cell. Further two diode model was also designed for this solar cell.

Recently, flexible electronic devices have gained tremendous research interest owing to their wide range of applications such as human motion detection, health monitoring and electronic skin (E-Skin). Particularly, the development of skin-like flexible strain sensors is gradually increasing for the realization of multipurpose human-machine interfaces. This paper aims to propose a simple method of manufacturing flexible graphene-based strain sensors with high sensitivity. Herein, a novel flexible resistive-strain sensor based on graphene nanoplatelets (GNP)/PDMS has been reported that provides good strain sensitivity, stretchability up to 65% with a gauge factor of 62.5, indicating typical piezo-resistive characteristics. The fabricated sensor is attached to the human body, it works as a health-monitoring device by detecting various human motions such as human wrist pulse measurement, the finger bending movement and in addition to the flexible pipe bending. This work presents fabrication, characterization and comparative study of four different types of GNP wrist pulse sensors. Therefore, with its simple structure and low cost processing coupled with reasonably good piezo-resistive behavior, it has great potential in wearable electronics, viz. human motion detection and health monitoring applications.

We report flexible organic solar cells composed of MEH-PPV (poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenyl vinylene]) and PEDOT:PSS (poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)) as photoactive layer and hole transport layer, respectively, fabricated using a simple solution processing method on flexible polyethylene terephthalate (PET) substrates. The current-voltage characteristics have been studied in PET based flexible devices having four different kind of structures such as graphene/PEDOT:PSS/PET, graphene/PEDOT:PSS/PEDOT:PSS/PET, graphene/MEH-PPV/PEDOT:PSS/PET and graphene/MEH-PPV/PEDOT:PSS/PEDOT:PSS/PET. Under AM 1.5G solar illumination, the devices with structure graphene/MEH-PPV/PEDOT:PSS/PEDOT:PSS/PET exhibits an open-circuit voltage (V-oc) of 2.549 V, a short-circuit current density (J(sc)) of 0.11 mAcm(-2), and a fill factor (FF) of 56.7%. The device shows an ideality factor of similar to 35 along with a diode reverse saturation current of 0.067 x 10(-6) mu A. We propose that incorporation of MEV-PPV into graphene and PEDOT:PSS based Schottky junction forming a double layer polymer structure, responsible for enhanced current conductionby replacing metallic nanoparticle into polymer blend leads to the significant improvement in solar output characteristics of the devices. In these bilayer structures metallic nanoparticles are not embedded into the polymer matrix and therefore it enhances the device stability and lifetime by eliminating the issues of phase separation between nanoparticles and polymers.