Device Configuration Research Articles

Giant Energy Harvesting via Maxwell Displacement Current Enhancement Using Metal Sheet Interspaced Hetero‐Layer Structured Piezo‐Composite Nanofiber Device

AbstractThe limited performance of piezoelectric nanogenerators (PENGs) has hindered their practical applications in self‐powered electronics. To address these limitations, this study presents a new design of a PENG that incorporates hetero‐layer structured piezo‐composite nanofibers with interspaced metal sheets. The hetero‐layer structure consists of alternating layers of ferroelectric barium titanate (BT) nanoparticles interfaced with poly(vinylidene fluoride‐co‐trifluoroethylene) (P(VDF‐TrFE)) composite nanofibers (P(VDF‐TrFE)/BT), and conductive graphite nano‐sheets (GNS)‐embedded P(VDF‐TrFE) composite nanofibers (P(VDF‐TrFE)/GNS) mats. The inclusion of interspaced metal sheets in the device configuration enhances the stress concentration effect, thereby effectively distributing the applied mechanical vibrations. Simultaneously, the P(VDF‐TrFE)/BT composite nanofibers improve the piezoelectric coefficient (187.86 pC N−1), while the P(VDF‐TrFE)/GNS composite nanofibers reduce the internal impedance of the device. These combined enhancements result in an increased Maxwell displacement current and power output. Consequently, the hetero‐layer structured PENG exhibits an impressive open circuit voltage (Voc) output of 350 V, a short circuit current (Isc) output of 6 µA, and a power output of 3.62 W m−2. Moreover, the developed PENG demonstrates extraordinary energy harvesting performance under harsh vibrations caused by human musculoskeletal movements, as well as subtle vibrations from heart pulses, emotional changes, and speech recognition. Additionally, the PENG shows its potential use in wearable self‐powered wireless e‐health systems.

Definition of a Localized Conducting Path via Suppressed Charge Injection in Oxide Memristors for Stable Practical Hardware Neural Networks.

Oxide-based memristors have been demonstrated as suitable options for memory components in neuromorphic systems. In such devices, the resistive switching characteristics are caused by the formation of conductive filaments (CFs) comprising oxygen vacancies. Thus, the electrical performance is primarily governed by the CF structure. Despite various approaches for regulating the oxygen vacancy distributions in oxide memristors, controlling the CF structure without modifying the device configuration related to material compatibility is still a challenge. This study demonstrates an effective strategy for localizing CF distributions in memristors by suppressing charge injection during the formation of conducting paths. As the injected charge quantity is reduced in the electroforming process of the oxide memristor, the CF distributions become narrower, leading to more reproducible and stable resistive switching characteristics in the device. Based on these findings, a reliable hardware neural network comprising oxide memristors is constructed to recognize complex images. The developed memristor has been employed as a synaptic memory component in systems without degradation for a long time. This promising concept of oxide memristors acting as stable synaptic components holds great potential for developing practical neuromorphic systems and their expansion into artificial intelligent systems.

High Isolation, Double-Clamped, Magnetoelectric Microelectromechanical Resonator Magnetometer.

Magnetoelectric (ME)-based magnetometers have garnered much attention as they boast ultra-low-power systems with a small form factor and limit of detection in the tens of picotesla. The highly sensitive and low-power electric readout from the ME sensor makes them attractive for near DC and low-frequency AC magnetic fields as platforms for continuous magnetic signature monitoring. Among multiple configurations of the current ME magnetic sensors, most rely on exploiting the mechanically resonant characteristics of a released ME microelectromechanical system (MEMS) in a heterostructure device. Through optimizing the resonant device configuration, we design and fabricate a fixed-fixed resonant beam structure with high isolation compared to previous designs operating at ~800 nW of power comprised of piezoelectric aluminum nitride (AlN) and magnetostrictive (Co1-xFex)-based thin films that are less susceptible to vibration while providing similar characteristics to ME-MEMS cantilever devices. In this new design of double-clamped magnetoelectric MEMS resonators, we have also utilized thin films of a new iron-cobalt-hafnium alloy (Fe0.5Co0.5)0.92Hf0.08 that provides a low-stress, high magnetostrictive material with an amorphous crystalline structure and ultra-low magnetocrystalline anisotropy. Together, the improvements of this sensor design yield a magnetic field sensitivity of 125 Hz/mT when released in a compressive state. The overall detection limit of these sensors using an electric field drive and readout are presented, and noise sources are discussed. Based on these results, design parameters for future ME MEMS field sensors are discussed.

Transport of Steam-Gas Mixture in Hydrodynamic Devices: A Numerical Study of Steam Reforming of Methane

The paper introduces a mathematical model that describes the cavitation process occurring during the passage of a water steam flow in various geometric configurations of a hydrodynamic device. The flow experiences a localized constriction (convergent nozzle) followed by expansion (divergent nozzle), exemplified by a Venturi tube or a Laval nozzle. A narrow flow channel connecting the convergent and divergent sections is equipped with a narrow-section nozzle for injecting methane molecules into the high-speed steam flow. As the steam-gas mixture passes through this zone, it is irradiated with an electron beam and sprayed into a cylindrical chamber at atmospheric pressure, where the distribution of methane molecules in water vapor forms an aerosol. Key geometric parameters of the constriction and expansion zones of the hydraulic system (cavitation-jet chamber) are determined to ensure the uniform distribution of dispersed-phase particles (methane) in the dispersion medium (water vapor). Velocity and pressure distributions of the mixed steam-gas flow are calculated using a turbulent mathematical model, specifically the k-ω model, while the motion of methane particles is simulated using a particle tracing method. The uniformity of methane molecule distribution in water vapor is assessed using Ripley’s K-function. The best performance of the hydrogen-producing chamber was observed when the cavitation-inducing nozzle’s convergence angle exceeded 50 degrees. The divergence angle of the nozzle within the range of 30–40 degrees provided the best distribution in terms of uniformity of the methane particles in the chamber.

Metal organic framework derived NiCo layered double hydroxide anode aggregated with biomass derived reduced graphene oxide cathode: A hybrid device configuration for supercapattery applications

Metal-organic frameworks (MOFs), due to its exceptional characteristics like high specific surface area and design diversity, serve as an outstanding sacrificial template in forming layered double hydroxides (LDHs) for highly efficient electrodes in supercapattery devices. In this work, we have prepared bimetallic layered Nickel Cobalt LDH via in-situ etching of Co-ZIF, in different Nickel concentrations directly on Ni foam that enhances the interfacial contact between substrate and the material. The optimised NiCo LDH-2 sample exhibited remarkable electrochemical behaviour with fast electrolyte ion diffusion kinetics ideal for supercapattery device and delivered a high specific capacitance of 2567 Fg−1 at 1 Ag−1. Further, the supercapattery device assembled with Ni-Co LDH as anode and rGO derived from a sustainable source as cathode demonstrated an energy density of 21 Whkg−1, power density of 0.307 kWkg−1 and good cyclic stability with capacitance retention of 88.89 % along with coulombic efficiency of 90.58 % over 1500 cycles. This work proposes an effective approach for designing layered NiCo-LDH that can be further extended to the synthesis of other transition metal-derived LDH for supercapattery devices.

Non‐Carbon‐Dominated Catalyst Architecture Enables Double‐High‐Energy‐Density Lithium–Sulfur Batteries

AbstractThe commonly used “catalyst on carbon” architecture as a sulfur host is difficult to jointly achieve high gravimetric and volumetric energy densities for lithium–sulfur (Li–S) batteries due to the contradiction between low tap density/poor catalytic activity of carbon and the easy agglomeration of metal‐based compounds without carbon. Here, a non‐carbon‐dominated catalytic architecture using macroporous nickel/cobalt phosphide (NiCoP) is reported as the sulfur host for Li–S batteries. The macroporous framework, which accommodates a large amount of sulfur, can accelerate the electrochemical reaction kinetics by accelerated e− transport, Li+ diffusion, and superior adsorption and catalytic activity of inherent Ni2P/CoP heterostructures. The high tap density (0.45 g cm−3) and mechanically hard features contribute to the excellent structural and physicochemical stability of the NiCoP@S electrode after the pressing and rolling process. These features enable the Li–S coin cell to exhibit excellent electrochemical performance under conditions of high sulfur loading (10.2 mg cm−2) and lean electrolyte (electrolyte/sulfur of 2 µL mg−1). Inspiringly, the assembled pouch cell can simultaneously deliver a gravimetric energy density of 345.2 Wh kg−1 and an impressive volumetric energy density of 952.7 Wh L−1 based on the entire device configuration.

DEVELOPMENT OF A VIRTUAL DEVICE FOR CONTROLLING THE CONDITION OF INDUSTRIAL UNITS NODES USING LABVIEW TOOLS

This article is devoted to the research, construction, configuration and implementation of a virtual device for monitoring the condition of nodes ofcomplex industrial units. Modern units used in heavy engineering require no less modern means of management, control and diagnostics of damage tosuch units and their components. The development of the structure of control tools is based on multi-level or multi-stage procedures of transformationsof incoming measuring signals from aggregates. As the structure of the control device, a structure with a two-stage implementation of the spectraltransformation of measurement signals – with a primary static transformation and a secondary static transformation – was chosen. The basis of theprimary static transformation is the spectral transformation procedure based on the wavelet transformation. The basis of the secondary statictransformation is the procedure of linear discrimination with the indication of the decisive rule. The article demonstrates and implements approaches tobuilding a virtual device in terms of creating a block diagram, developing software, organizing the front panel of the device, setting up and carryingout simulation modeling for blocks of primary and secondary static transformations. The research uses the LabView platform. To prepare incomingmeasurement signals from nodes of industrial units, in the first block, the procedures of graduation, calibration and normalization of the target functionare carried out. To receive input measuring signals from units of industrial nodes, the COM port of the computer is used which, according to thedeveloped program, polls the COM port and inputs measuring signals to the primary static transformation procedure. The article describes a completevirtual control device that is formed and tested, which structurally contains all the blocks for achieving the control result and indicating the controlresult on the graphic interpretation of the computer.

Carrier multiplication in perovskite solar cells with internal quantum efficiency exceeding 100%

Carrier multiplication (CM) holds great promise to break the Shockley-Queisser limit of single junction photovoltaic cells. Despite compelling spectroscopic evidence of strong CM effects in halide perovskites, studies in actual perovskite solar cells (PSCs) are lacking. Herein, we reconcile this knowledge gap using the testbed Cs0.05FA0.5MA0.45Pb0.5Sn0.5I3 system exhibiting efficient CM with a low threshold of 2Eg (~500 nm) and high efficiency of 99.4 ± 0.4%. Robust CM enables an unbiased internal quantum efficiency exceeding 110% and reaching as high as 160% in the best devices. Importantly, our findings inject fresh insights into the complex interplay of various factors (optical and parasitic absorption losses, charge recombination and extraction losses, etc.) undermining CM contributions to the overall performance. Surprisingly, CM effects may already exist in mixed Pb-Sn PSCs but are repressed by its present architecture. A comprehensive redesign of the existing device configuration is needed to leverage CM effects for next-generation PSCs.

Interaction graph-based characterization of quantum benchmarks for improving quantum circuit mapping techniques

To execute quantum circuits on a quantum processor, they must be modified to meet the physical constraints of the quantum device. This process, called quantum circuit mapping, results in a gate/circuit depth overhead that depends on both the circuit properties and the hardware constraints, being the limited qubit connectivity a crucial restriction. In this paper, we propose to extend the characterization of quantum circuits by including qubit interaction graph properties using graph theory-based metrics in addition to previously used circuit-describing parameters. This approach allows for an in-depth analysis and clustering of quantum circuits and a comparison of performance when run on different quantum processors, aiding in developing better mapping techniques. Our study reveals a correlation between interaction graph-based parameters and mapping performance metrics for various existing configurations of quantum devices. We also provide a comprehensive collection of quantum circuits and algorithms for benchmarking future compilation techniques and quantum devices.

Accurate Weight Update in an Electrochemical Random‐Access Memory Based Cross‐Point Array Using Channel‐High Half‐Bias Scheme for Deep Learning Accelerator

AbstractRecently cross‐point arrays of synaptic memory devices have been intensively studied to accelerate deep neural network computations. Among various synaptic devices, electrochemical random‐access memory (ECRAM) is emerging as a promising non‐volatile memory candidate owing to its superior synaptic characteristics. However, an optimized update scheme for a three‐terminal ECRAM‐based cross‐point array is yet to be developed. In this study, a metal‐oxide‐based ECRAM (MO‐ECRAM) shows superior synaptic characteristics and the weight update of devices in the MO‐ECRAM cross‐point array is analyzed using the half‐bias (HB) scheme. Additionally, A channel‐high half‐bias (CHB) scheme is proposed to overcome the degraded selectivity of the weight update caused by the three‐terminal configuration of the ECRAM device. In the CHB scheme, the conductance change in the selected device can be increased considerably by applying a calculated additional voltage to the channel. Using the CHB scheme, parallel and selective updates are successfully performed in a 2 × 2 MO‐ECRAM cross‐point array. Finally, an experimental demonstration of the training algorithm shows the impact of selective updates when using the CHB scheme. This new update scheme is expected to improve training accuracy in ECRAM cross‐point array‐based deep learning accelerators.

6-20 GHz 30% ScAlN Lateral Field-Excited Cross-Sectional Lamé Mode Resonators for Future Mobile RF Front Ends.

This article reports on 30% scandium-doped AlN (ScAlN) lateral field-excited (LFE) cross-sectional Lame' mode resonators (CLMRs) with unprecedented performance in the 6-20 GHz range. By combining high-crystallinity 30% ScAlN piezoelectric thin films, a lithographic tunability of the resonance frequency, and a simple three-mask post-CMOS compatible fabrication process, we propose a technology platform that can enable the mass production of low-loss, wideband, and compact microacoustic filtering devices spanning a wide spectrum portion on the same chip for the next-generation radio frequency front ends (RFFEs) of handsets. This article demonstrates a successful scaling of the microacoustic technology well beyond the sub-6-GHz fifth-generation (5G) band, as well as the outstanding capabilities of high-crystallinity 30% ScAlN piezoelectric layers in delivering high-quality factor ( Q ) and high-electromechanical coupling ( kt2 ) resonators, notably exceeding the state of the art in terms of relevant figures of merit (FOMs). Furthermore, we experimentally investigate the impact of geometrical parameters, such as tethering configuration and width-over-length ratio on the devices' 3-dB quality factor ( [Formula: see text]), power linearity (PL), and temperature coefficient of frequency (TCF). By adopting a statistical approach for data analysis, we determine the optimal geometry to maximize the Q value. Moreover, we experimentally demonstrate that a fully tethered device's configuration ensures superior PL, lower TCF, and higher device yield and select that as the best design tradeoff between all the variables under consideration. Finally, we discuss a further scaling of LFE CLMRs, both in terms of higher doping levels in the piezoelectric layer, in order to enhance the performance of microacoustic filters, and in terms of higher operation frequencies, in order to reach and cover the mm-wave spectrum.

Computational optimization of acoustofluidic devices for advanced particle micromanipulation

Acoustofluidic devices, which combine principles of acoustics and microfluidics, have emerged as a promising platform for biological micro-object micromanipulation due to their non-invasive, accurate, rapid, and label-free qualities. Acoustofluidic devices have found utility in various biomedical applications including single-cell studies, point-of-care testing, lab-on-a-chip studies, and tissue engineering. In this work, we present novel device configurations which enable complex and high-resolution control of suspended micro-objects. The studies presented here utilize computational analysis to optimize (1) traveling surface acoustic wave device dimensions, (2) the configuration of a planar acoustic resonator that integrates a structured surface, (3) the thickness of the coupling layer and superstrate materials for bulk-wave transmission, and (4) the shape of acoustically actuated 3-D microstructures. These devices were verified experimentally to generate highly localized acoustic fields and acoustic streaming effects enabling rapid and spatially controllable particle capture, transport, and patterning. In doing so, this work demonstrates that computational analysis is an integral part of the development of acoustofluidic devices for advanced micromanipulation, which have extensive potential in biomedical applications.

Comparing the benefits of hearing aids and cochlear implants in real-world listening environments

Comparing outcomes between patients with bilateral hearing aids (HAs), bilateral cochlear implants (CIs), and bimodal fittings (CI + HA) are difficult because of the variations in hearing performance between the different devices and patient groups. This may impact patient counselling, device selection, and hearing outcomes for listeners with more severe hearing loss. This study seeks to identify the factors impacting the listening abilities of adults fitted with bilateral HAs, bilateral CIs, and bimodal fittings in noisy environments by comparing outcomes from commonly used clinical tests and a new task that emphasises realistic listening in background noise. By identifying these limiting factors from a variety of tests, optimising hearing aid fittings, and comparing between device configuration groups, the study will help understand where hearing aid devices no longer meet satisfactory individual outcomes, and a cochlear implant may improve long-term performance. This approach pushes toward considering real-world outcomes through realistic test measures when informing clinical counsel and device implantation or configuration recommendations. As such, adults with hearing loss can receive more tailored advice that validates their daily listening concerns and clinicians are granted a better understanding of how to improve the quality of life for their clients.

The effect of pressure anisotropy on 3-D MHD stability for low magnetic field LHD equilibria

The magnetohydrodynamic stability of plasmas with an anisotropic pressure component is analysed for a low magnetic field configuration of the large helical device. Magnetic equilibria are calculated by the anisotropic Neumann inverse moments equilibrium code, an extension of the three-dimensional variational moments equilibrium code. A modified version of the bi-Maxwellian is used to model the anisotropic particle velocity distribution. Magnetohydrodynamic stability calculations for the $n=1$ mode family are carried out by TERPSICHORE, which has been expanded by the Kruskal–Oberman energy principle. For on-axis particle deposition, the growth rate and plasma displacement show that the parallel dominant plasmas are significantly more stable than isotropic or perpendicular dominant plasmas. For off-axis particle deposition, the growth rate and the Mercier criterion in the peripheral region $\rho =0.9$ , show that low field (LF) deposition perpendicular dominant plasmas are most unstable. For the most realistic off-axis deposition profile, it is found that parallel dominant plasmas are most stable for LF deposition, while perpendicular dominant plasmas are most stable for high field deposition. We conclude that, under low magnetic field conditions in the large helical device, tangential neutral beam injection heating has a stabilising influence on the plasma.

Study of thermally evaporated Sb2Se3-based substrate-configured solar cell

Antimony selenide (Sb2Se3) has emerged as a promising absorber material for thin film solar cell (TFSC) application. In this work, a (120) oriented substrate-configured Sb2Se3 based TFSC has been fabricated using the thermally evaporated Sb2Se3 thin films. Pre-synthesized bulk Sb2Se3 was used as a source material and the films were subjected to post-deposition selenization. TFSCs were fabricated in a device configuration of Glass/Mo/Sb2Se3/CdS/ITO/Ag. It was found that there is a significant increment in the power conversion efficiency (PCE) with increased Voc and Jsc in the devices, wherein the Sb2Se3 absorber films were subjected to post-deposition selenization compared to the devices made with as-deposited films. TFSC with as grown Sb2Se3 film was showing an efficiency of ∼ 1% with Voc ∼ 208 mV, Jsc∼16 mA cm−2 and fill factor (FF) ∼ 29.9%. The device with selenized Sb2Se3 films showed a power conversion efficiency of 3.38% with Voc, Jsc and FF values of 362 mV, 18.54 mA cm−2 and 50.39%, respectively. The increase in PCE for selenized films is attributed to better grain growth and suppression of selenium vacancy defects. Overall, the findings of this work demonstrate the potential prospects of Sb2Se3 as an absorber material for TFSCs applications and suggest that post-deposition selenization plays a significant role in the enhancement of device efficiency. The obtained results are contributive in the understanding and development of low-cost Sb2Se3-based TFSCs.

Attacks and vulnerabilities of Wi-Fi Enterprise networks: User security awareness assessment through credential stealing attack experiments

Enterprise Wi-Fi networks are essential for businesses and public administrations as they provide a perfectly scalable and secure system. In the university environment, they are often deployed to offer services to students. One of the most famous university Wi-Fi Enterprise networks is Eduroam, which stands for education roaming; it is a worldwide Wi-Fi access and roaming service widely adopted by the international research and education community. It is based on 802.1x mechanisms that use TLS tunnels for achieving mutual authentication goals, and, as such, it requires careful configuration of mobile devices and responsible users’ behaviors to avoid trivial attacks carried out with rogue Access Points (APs). Differently than employees in a corporate network whose devices are properly configured by ICT teams, the user base of Eduroam consists of (likely) millions of students and professors around the world, with a myriad of different and uncontrolled devices. To assess the security of 802.1x in general, and more specifically that of Eduroam, we ran attacks against two communities of students of increasing size in order to test how users (and their devices) react when rogue 802.1x APs appear in the list of available networks. We then focused our attention on devices, and investigated their detailed dependence on different WPA-Enterprise configurations and certificate settings. The aftermath is that, even with a completely passive attack (users are keeping devices in their pockets), it is possible to steal credentials from more than one-third of the students. While most of the 802.1x vulnerabilities employed in this work should be considered somewhat known (being disclosed in former technical papers), our work appears to raise a threefold concern: (i) most pragmatic 802.1x configurations appear to be grossly insecure; (ii) no Apple’s iPhone felt in our attack unless explicitly forced by the user, owing to its reduced possibility for a user to misconfigure the terminal; and (iii) the awareness of Wi-Fi authentication threats even in relatively skilled end users is close to zero.

Photosensitivity reversal in solution-processed Copper Zinc Tin Sulphide/Cadmium Sulphide superstrate junction

Inverse photosensitivity is a sought-after property for the development of photonic devices and non-volatile memories with low power conversion. Herein, we report on the development of a superstrate-type thin film junction exhibiting inverse photosensitivity which does not involve the use of a pricy transparent conducting oxide layer, providing a method for engineering low-cost thin film devices. Sequential ionic layer adsorption reaction (SILAR) was used to grow Copper Zinc Tin Sulphide (CZTS) and Cadmium sulphide (CdS) large area thin film p-n diode junction. Uniform CZTS thin films with an area of ∼10 cm2 which were free of pin holes or voids could be deposited using an optimized SILAR process recipe. The grown CZTS films exhibited an electrical resistivity of 4.4 × 10−4 Ωm using silver (Ag) electrodes. CdS thin films were sub-sequentially grown over the CZTS layer to form a p-n junction. A knee voltage of 0.2 V in the device configuration “glass/CZTS/CdS/Ag” was observed in the current voltage characteristics. The as-prepared and the vacuum-annealed p-n junction exhibited negative photosensitivity of magnitude 0.21 and 0.16 respectively. The air-annealed device structure exhibited photosensitivity of 216.

Should lateral wall collapse be a contraindication for hypoglossal nerve stimulation?

ObjectiveThe purpose of this study is to examine how lateral wall collapse affects treatment outcomes for hypoglossal nerve stimulation (HNS) patients. MethodsPatients (n = 111) queried from a single surgeon's database of HNS cases were divided into groups based on their degree of oropharyngeal lateral wall collapse noted on drug-induced sleep endoscopy (DISE): Complete, Partial, None. For each group, apnea hypopnea index (AHI) reduction, Epworth Sleepiness Scale (ESS) score, stimulation voltage, average nightly usage, need for alternate device configuration/awake sleep endoscopy, and rate of surgical success were collected. Patients with Complete collapse were compared to those with Partial/None via Student's t-tests and Pearson's Chi-square test. ResultsOf the 111 eligible patients, 45 had complete, 30 partial, and 36 had no lateral oropharyngeal wall collapse. There were no statistically significant differences found between the Complete and Partial/None groups in terms of age, BMI, sex, AHI (pre and post-op), ESS (pre and post-op), voltage, alternate device configuration, or nightly adherence. Notably, a significantly greater number of the Partial/None group had surgical success (84.84 % vs 66.67 %, p = 0.024). ConclusionsPatients with Partial/None oropharyngeal collapse were significantly more likely than patients with Complete lateral wall collapse to see surgical success. There are many factors to weigh when assessing a patient's surgical candidacy, it is clear that complete lateral wall collapse at the level of the oropharynx is a negative predictor for success in HNS.

Polycrystalline phases grown in-situ engendering unique mechanism of charge storage in polyaniline-graphite composite

We report on a simple surfactant/template free chemical route for the synthesis of semi-polycrystalline polyaniline-graphite (SPani-graphite) composite and its application as an electroactive material in electrochemical charge storage. The synthesized material exhibits well-defined poly-crystallographic lattices in high resolution transmission electron micrographs and sharp peaks in x-ray diffraction spectra suggesting crystalline nature of the material. The specific capacitance computed from the galvanostatic charge-discharge (GCD) data obtained from 3-electrode cell configuration using 1 M aq. Na2SO4 as an electrolyte was 111.4 F g−1 at a current density of 0.1 A g−1 which rises to 269 F g−1 at an elevated current density of 1.0 A g−1. A similar pattern of increase in the specific capacitance values with an increase in the current density was observed in the results obtained from 2-electrode symmetric device configuration using polymer gel electrolyte (xanthan gum in 1 M aq. Na2SO4). The specific capacitance computed from the GCD data obtained from the device configuration was 20 F g−1 at the current density of 1.0 A g−1. The device delivers an energy density of 1.7 Wh kg−1 and a power density of 2.48 kWh kg−1 at an applied current density of 0.5 A g−1 suggesting an excellent rate capability and power management. In addition, the device exhibits ⁓92 % specific capacitance retention up to 8000 continuous GCD cycles and ⁓80 % coulombic efficiency up to 10,000 continuous GCD cycles indicating excellent cycling stability. The unique feature of increasing specific capacitance with respect to applied current density is attributed to the presence of semi-polycrystalline phases in the SPani-graphite matrix. The material behaves as a surface redox supercapacitor and its unique mechanism of charge storage is discussed in detail in the article.

Funabot-Suit: A bio-inspired and McKibben muscle-actuated suit for natural kinesthetic perception

In recent years, there has been extensive utilization of actuators driven by artificial muscles in wearable devices. However, the muscle distribution configurations of most wearable devices have been specifically designed and are difficult to generalize. Consequently, wearable devices that allow direct installation of actuators onto existing clothing are better suited for a wider range of application scenarios. This letter presents the development and evaluation of Funabot-Suit, a human muscle configuration inspired wearable assist device that employs McKibben artificial muscles to induce natural kinesthetic perception in the wearer’s torso. By integrating thin McKibben muscles into an existing motion capture suit, the Funabot-Suit is capable of generating four fundamental motions: forward and backward bending, and left and right twisting. The suit’s performance was assessed through experiments involving three subjects who wore the suit while standing and seated, with the subjects reporting the direction of their kinesthetic perception. The subjects also rated the perceived ease of kinesthetic perception direction on a five-point scale. Our results demonstrate that the Funabot-Suit successfully induces kinesthetic perceptions for the wearer, with a one hundred percent detection ratio for accurate responses in the command direction across all subjects and positions. We observed variations in the sensitivity of left–right and up-down sensations, which can be attributed to the positioning of artificial muscles and individual differences.