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The demand for highly sensitive and reliable strain sensors is increasing in the fields of wearable technology and medical diagnostics. Here, we report a novel approach to fabricating a strain sensor specifically designed for medical applications using zinc oxide (ZnO) nanofiber mats as its matrix. A composite material containing zinc oxide and PVP polymer has been synthesized together to generate ZnO nanofiber mats by employing an electrospinning method which allows precise control over morphology, alignment of the fibers, and for device fabrication, we utilize magnetron sputtering. Using scanning electron microscopy (SEM), the structural and morphological characteristics of the as-synthesized multiple nanofiber mats are characterized. The fabricated strain sensor demonstrates outstanding sensitivity, with a gauge factor (GF) of 1653 having very small diameter, enhancement in stretching limits of up to 7.5%, a reaction time of 300 ms, and the fabricated strain sensor recovering its morphology within 420 ms. Furthermore, the sensor has outstanding biocompatibility and can be used to detect human motion, forearm movements, pulse, wrist bendability, and speech for individuals who are unable to speak. Overall, this work demonstrates an effective strategy for the fabrication of highly sensitive strain sensors for use in medical applications. [ABSTRACT FROM AUTHOR]

Flexible and wearable charge storage devices are the dire need of modern technology. This work is focused on an all-flexible strategy, both in terms of electrolyte selection and electrode fabrication in order to develop a supercapacitor. For electrode fabrication, sodium silicate is used as a flexible binder which provides flexibility to the electrode material without compromising its conductivity. A chemical binder provides multifold advantage of flexibility of the electrode as well as the capacitive nature of the material. Thus, the binder acts as a dynamic variant, attracting the collected charge carriers to itself rather than recombining them at the separator layer, improving the supercapacitor's self-discharge ability. To transport ions, Polyvinyl Alcohol is chosen as a separator, whereas KOH and H3PO4 are chosen as electrolytes. To improve the electrode flexibility, four different electrode materials are mixed with sodium silicate solution, including single and double mass activated carbon and reduced Graphene Oxide (rGO). At pre-fabrication stage, the integral components i.e., electrodes, electrolytes and binders are individually characterized by multiple evaluation techniques. Furthermore, the effect of rGO on the performance of supercapacitors is studied in detail. The next-generation Randless model is evaluated for better charge collection and prevention of charge recombination in the supercapacitors. Herein, the open and short-circuit states of the fabricated supercapacitors are evaluated where all the supercapacitors are charged for about 3 min and are fully discharged in more than 30 min. The addition of rGO in double mass activated carbon is also found to reduce the overall charge collection. [ABSTRACT FROM AUTHOR]

This study focuses on the large-scale production of a high-energy-density supercapacitor through the cost-effective polymerization of a PANI/Cr2O3/graphene nanocomposite, utilizing commercially available flexible substrate and cost-effective chemicals. To explore the synergistic effect, a PANI/Cr2O3/graphene nanocomposite is evaluated in a hybrid gel electrolyte with varying polyvinyl alcohol (PVA) concentrations. The investigation is aimed at enhancing the electrochemical performance of electrode material for supercapacitors. Two symmetric devices are fabricated to assess the specific capacitance and energy density of the prepared nanocomposite. In the PVA2g/Na2SO4 electrolyte, the energy density is increased to 61.71 Wh kg−1, accompanied by an enhanced potential window of 1.95 V. Furthermore, the prepared composite demonstrates good electrochemical stability, retaining 94% of its initial capacitance after 2000 cycles at 2 Ag−1 in 2 g PVA/Na2SO4 gel electrolyte. The remarkable electrochemical properties of the composite can be attributed to the effective contact and synergistic effect among PANI, Cr2O3, and graphene, making it a promising candidate for supercapacitor applications. Moreover, this facile process is easily scalable to meet commercial demands and can be utilized to enhance the energy density of various carbon-based materials with limited initial performance. [ABSTRACT FROM AUTHOR]

Wide band-gap semiconductor materials such as SiC have created a contemporaneous worldwide interest in high power electronic applications and boosted the research possibilities. Consequently, the voltage handling capability of SiC Thyristor is being analyzed and improved. This paper presents the modelling and simulation of design variants of 4H-SiC Thyristor. In this work, a fabless approach is used to create the design variants of Thyristor in Silvaco TCAD. Key performance parameters such as drift region thickness and doping, anode width and area pertaining to the high blocking voltage are investigated by employing advanced numerical algorithms and physical models using mixed-mode simulation. Concepts of improving the electrical parameters like breakdown voltage, critical electric field and on-state resistance have been formulated here by employing structural parameters. Five design variants were simulated, which could block 1 kV, 3 kV, 5 kV, 10 kV and 15 kV. Moreover, the impact of variation of critical parameters i.e. drift region thickness (13μm to 220μm), doping (1014 cm−3 to 1020 cm−3),anode width (2μm to 51μm) and area of device on electrical characteristics have been portrayed to have a clear insight on device design considerations. Obtained results are compared with theoretical data, demonstrating a good agreement between simulated and theoretical values. Finally, a trade-off between breakdown voltages and on-state resistance of simulated designs for specific range of doping concentrations is discussed. [ABSTRACT FROM AUTHOR]

We report a cost-effective, chemical polymerization route to synthesize PANI/Co3O4/graphene (PCG) ternary nanocomposite for supercapacitor applications to achieve enhanced energy density in a cost-effective, non-toxic, and non-corrosive neutral aqueous electrolyte of 1M Na2SO4. These properties are advantageous for a supercapacitor assembling procedure, being favorably facile and inexpensive. The electrochemical analysis was carried out to check analyte performance with cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS). The PCG ternary nanocomposite exhibits a specific capacitance of 183 F g−1 at 1 A g−1 in a two-electrode device, and retains its 93% of initial specific capacitance after 2000 cycles. The energy density of PCG ternary nanocomposite is 49.81 Wh Kg−1 with a power density of 697.72 W Kg−1. The excellent electrochemical properties of the PCG ternary nanocomposite are credited to the good contact and the synergistic effect between the PANI nanofibers, Co3O4 nanoparticles, and graphene nanosheets. This indicates that this synthesized ternary nanocomposite material could be used as a promising candidate for supercapacitor electrode material. [ABSTRACT FROM AUTHOR]

Energy is the most dependable need of the current era. With the tendency in portable electronics and self-powered systems, researchers have been developing nanogenerators and utilizing them as self-powered energy source. High output and optimum efficiency are always a key concern. Hence, in this research work, a hybrid NG based on both piezoelectric and triboelectric phenomena is proposed and utilized for harvesting wind energy. The UV curable polyurethane (PU) and a composite of zinc oxide (ZnO) in powder form with UV curable PU (ZnO + PU) are utilized for fabricating the triboelectric NG (TENG) and Piezoelectric NG (PNG), respectively. To combine the effect of both PNG and TENG, these two nanogenerators are stacked using a sponge as a spacer by providing a uniform air gap for triboelectrification. The hybrid nanogenerator module was connected in parallel to collect the electrical energy harvested. The fabricated hybrid nanogenerators effectively produced an open-circuit voltage of ~ 120 V and current density of ~ 140 µA cm−2 across 50 Ω resistor during fast speed wind from a stand fan. Apart from that, the developed hybrid NG can light up to 50 commercial LEDs, implying that the proposed hybrid NG can be used as a self-powered energy source in portable electronics, wireless and monitoring systems. [ABSTRACT FROM AUTHOR]

Poly-vinyl alcohol (PVA)-based electrolytes can play a vital role in the development of supercapacitors by providing a desirable charge separator layer with an added advantage of stretchable nature. These properties enable them as a global contender in wearable electronics and charge storage applications. In this study, the PVA-based electrolyte has been synthesized with potassium hydro-oxide (KOH) as ionic migration agent, which may enhance the electronic double-layers capacitance (EDLC) phenomena. In order to mechanically strengthen the graphene-based activated carbon, larger pore fabric is utilized for its encapsulation. Post-fabrication analysis of the supercapacitor using the standard imaging/microscopy techniques (scanning electron microscopy, electron-dispersive electroscope, and atomic force microscopy) are carried out as initial diagnostic test. For detailed electrical, optical, and charge-based evaluation, electrochemical impedance spectroscopy (EIS), Nyquist plot analysis, current–voltage (I–V) measurements, charged deep-level transient spectroscopy (Q-DLTS), and photoluminescence spectroscopy (PLs) are performed. The fabricated supercapacitor took ~ 30 min to completely discharge itself at "full load operation." The band diagram, at carrier transport levels, has also revealed the presence of two possible trap centers which may be responsible for the degradation and/or overall stability of the supercapacitor. [ABSTRACT FROM AUTHOR]

A new electrochromic conjugated polymer, poly 2-(9,9-dicotyl-9 H-fluorene-2-yl)-3,6-bis(5-hexylthiophen-2-yl)thieno[3,2- b]thiophene), containing fluorene (F8-DT6) substituted thieno[3, 2-b]thiophene has been designed by Stille and Suzuki coupling reactions and then polymerized at different potentials through electrochemical polymerization. The as-synthesized polymer is characterized by nuclear magnetic resonance (NMR) spectroscopy, cyclic-voltammetry (CV), ultraviolet-visible spectroscopy (UV-vis), and atomic force microscopy (AFM). The lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) energy levels are −2.67 eV and −5.21 eV respectively, as determined by cyclic voltammetry. As the film, P(F8-DT6-TT) exhibits UV-vis at 502 nm, the bandgap values from electrochemical and optical measurements are in excellent agreement. The CIE colour coordinates L*, a*, and b* of neutral and oxidized states are (76.81, −3.04, 67.46) and (68.90, −10.92, 32.04) respectively giving vivid orange colour in the bleached/oxidation state and a very light-yellow colour in the reduced state. P(F8-DT6-TT) exhibits better stability between −0.1 and 2 V and the stability pattern moves towards a stable position by increasing the number of cycles. AFM images reveal a higher root-mean-square value (51.83 nm) that is useful for providing a convenient optical response and film stability. Effective colour tuning by substituting fluorene (F8-DT6) in thieno[3,2-b] thiophene units is a notable property of P(F8-DT6-TT), which renders it an appropriate electrochromic material. [ABSTRACT FROM AUTHOR]

In this paper, we present a novel one-step, easy and cost-effective method for the synthesis of Ag-doped TiO2 sol and deposition of its compact thin films by spin coating technique. The effects of dopant quantity (0–5% by weight) on structural, morphological, optical and electrical properties of TiO2 thin films have been investigated and reported. The X-ray Diffraction (XRD) spectra revealed single anatase phase having no secondary phases. The scanning electron microscopy (SEM) showed pinholes-free/compact thin films composed of spherical nanoparticles where the particle size has been demonstrated to decrease with increasing Ag doping. The atomic force microscopy (AFM) confirmed smooth and compact TiO2 thin films, however, the surface roughness tends to grow with increasing the dopant quantity. The X-ray fluorescence spectroscopy (XRF) revealed the presence of Ag mass percentage in the relevant samples, which has been demonstrated to grow with increasing the amount of dopant. The UV–Vis spectroscopy concluded the bandgap reduction of pure anatase phase of TiO2 (3.38 eV) as the Ag doping reaches to its maximum value of 5% (3.18 eV). Spectroscopic Ellipsometry has been employed to determine the thickness of thin films which was found to be in the range of ~ 100 nm, while electrical properties have been measured through DC-Hall Effect technique. It was found that the conductivity of thin films improved from 5.74 × 10–2 to 2.72 × 10–1 Ω−1 cm−1 on glass while on FTO-coated glass substrates, a higher value of 1.51 × 104 Ω−1 cm−1 was achieved. [ABSTRACT FROM AUTHOR]

In recent years, self-healing property has getting tremendous attention in the future wearable electronic. This paper proposes a novel cut-able and highly stretchable strain sensor utilizing a self-healing function from magnetic force of magnetic iron oxide and graphene nano-composite on an engineered self-healable polyurethane substrate through commercialized inkjet printer DMP-3000. Inducing the magnetic property, magnetic iron oxide is applied to connect between graphene flacks in the nano-composite. To find the best nano-composite, the optimum graphene and magnetic iron oxide blending ratio is 1:1. The proposed sensor shows a high mechanical fracture recovery, sensitivity towards strain, and excellent self-healing property. The proposed devices maintain their performance over 10,000 times bending/relaxing cycles, and 94% of their function are recovered even after cutting them. The device also demonstrates stretchability up to 54.5% and a stretching factor is decreased down to 32.5% after cutting them. The gauge factor of the device is 271.4 at 35%, which means its sensitivity is good. Hence, these results may open a new opportunity towards the design and fabrication of future self-healing wearable strain sensors and their applied electronic devices. [ABSTRACT FROM AUTHOR]