Design of an exoskeleton with minimized energy consumption based on using elastic and dissipative elements

This study proposes the design of an exoskeleton featuring minimized energy consumption during stand-to-sit and sit-to-stand (STS) motion and walking while carrying a load through the utilization of elastic and dissipative elements. In order to determine which phase and joint can utilize elastic and dissipative elements, we analyzed a human’s walk and STS motions. With this human motion data, we propose an elastic element for hip adduction and abduction (Ad/Ab), series dissipative actuation (SDA) using a semi-active hydraulic system for hip flexion and extension (Fl/Ex) and parallel elastic and series dissipative actuation (PESDA) for the knee Fl/Ex, which is combined with the SDA and the parallel elastic element. The effect of the developed exoskeleton (EXO) with a hip Ad/Ab spring, hip SDA and knee PESDA was evaluated by measuring the user’s ground reaction force (GRF). When wearing the EXO with a hip Ad/Ab spring, hip SDA and knee PESDA, the subject’s GRF was smaller as compared to when the subject was not wearing the EXO while walking and performing the STS motion under a 20-kg load condition, except during the heel strike of the walk motion.

     

Numerical and experimental assessments of focused microwave thermotherapy system at 925 MHz

This work investigated three‐dimensional (3D) focused microwave thermotherapy (FMT) at 925 MHz for a human tissue mimicking phantom using the time reversal (TR) principle for musculoskeletal disorders. We verified the proposed TR algorithm by evaluating the possibility of 3D beam focusing through simulations and experiments. The simulation, along with the electromagnetic and thermal analyses of the human tissue mimicking phantom model, was conducted by employing the Sim4Life commercial tool. Experimental validation was conducted on the developed FMT system using a fabricated human tissue mimicking phantom. A truncated threshold method was proposed to reduce the unwanted hot spots in a normal tissue region, wherein a beam was appropriately focused on a target position. The validation results of the simulation and experiments obtained by utilizing the proposed TR algorithm were shown to be acceptable. Effective beam focusing at the desired position of the phantom could be achieved.     

Performance Optimization of Parallel‐Like Ternary Organic Solar Cells through Simultaneous Improvement in Charge Generation and Transport

Ternary organic photovoltaic (OPV) devices with multiple light‐absorbing active materials have emerged as an efficient strategy for realizing further improvements in the power conversion efficiency (PCE) without building complex multijunction structures. However, the third component often acts as recombination centers and, hence, the optimization of ternary blend morphology poses a major challenge to improving the PCE of these devices. In this work, the performance of OPVs is enhanced through the morphological modification of nonfullerene acceptor (NFA)‐containing binary active layers. This modification is achieved by incorporating fullerenes into the layers. The uniformly dispersed fullerenes are sufficiently continuous and successfully mediate the ordering of NFA without charge or energy transfer. Owing to the simultaneous improvement in the charge generation and extraction, the PCE (12.1%) of these parallel‐linked ternary devices is considerably higher than those of the corresponding binary devices (9.95% and 7.78%). Moreover, the additional energy loss of the ternary device is minimized, compared with that of the NFA‐based binary device, due to the judicious control of the effective donor:acceptor composition of the ternary blends.     

Adiponitrile (C6H8N2): A New Bi‐Functional Additive for High‐Performance Li‐Metal Batteries

Rechargeable batteries with a Li metal anode and Ni‐rich Li[Ni_xCo_yMn_1?x?y]O₂ cathode (Li/Ni‐rich NCM battery) have been emerging as promising energy storage devices because of their high‐energy density. However, Li/Ni‐rich NCM batteries have been plagued by the issue of the thermodynamic instability of the Li metal anode and aggressive surface chemistry of the Ni‐rich cathode against electrolyte solution. In this study, a bi‐functional additive, adiponitrile (C₆H₈N₂), is proposed which can effectively stabilize both the Li metal anode and Ni‐rich NCM cathode interfaces. In the Li/Ni‐rich NCM battery, the addition of 1 wt% adiponitrile in 0.8 m LiTFSI + 0.2 M LiDFOB + 0.05 M LiPF₆ dissolved in EMC/FEC = 3:1 electrolyte helps to produce a conductive and robust Li anode/electrolyte interface, while strong coordination between Ni⁴⁺ on the delithiated Ni‐rich cathode and nitrile group in adiponitrile reduces parasitic reactions between the electrolyte and Ni‐rich cathode surface. Therefore, upon using 1 wt% adiponitrile, the Li/full concentration gradient Li[Ni_0.73Co_0.10Mn_0.15Al_0.02]O₂ battery achieves an unprecedented cycle retention of 75% over 830 cycles under high‐capacity loading of 1.8 mAh cm^?2 and fast charge–discharge time of 2 h. This work marks an important step in the development of high‐performance Li/Ni‐rich NCM batteries with efficient electrolyte additives.     

Heterogeneous,Porous 2D Oxide Sheets via Rapid Galvanic Replacement: Toward Superior HCHO Sensing Application

2D heterogeneous oxide nanosheets (NSs) have attracted much attention in various scientific fields owing to their exceptional physicochemical properties. However, the fabrication of 2D oxide NSs with abundant p–n interfaces and large amounts of mesopores is extremely challenging. Here, a facile synthesis of highly porous 2D heterogeneous oxide NSs (e.g., SnO₂/CoO_x) is suggested through a 2D oxide exfoliation approach combined with a fast galvanic replacement reaction (GRR). The ultrathin (<5 nm) layered CoO_x NSs are simply prepared by ion‐exchange exfoliation and a subsequent GRR process that induces a rapid phase transition from p‐type CoO_x to n‐type SnO₂ metal oxides (<10 min). The controlled GRR process enables the creation of heterogeneous SnO₂/CoO_x NSs consisting of small SnO₂ grain sizes (<10 nm), high porosity, numerous heterojunctions, and sub‐10 nm thickness, which are highly advantageous characteristics for chemiresistive sensors. Due to the advantage of these features, the porous SnO₂/CoO_x NSs exhibit an unparalleled HCHO‐sensing performance (R_air/R_gas > 35 @ 5 ppm with a response speed of 9.34 s) with exceptional selectivity compared to that of the state‐of‐the‐art metal oxide‐based HCHO gas sensors.     

High Dielectric,Robust Composite Protective Layer for Dendrite‐Free and LiPF6 Degradation‐Free Lithium Metal Anode

The development of lithium metal anodes for next generation batteries remains a challenge. Uncontrolled Li dendrite growth not only induces severe safety issues but also leads to capacity fading by continuously consuming the electrolyte. This study demonstrates the design and fabrication of a composite protective layer composed of a high dielectric polymer, inorganic particles, and an electrolyte to overcome these obstacles. This layer not only suppresses dendrite growth, but also prevents LiPF₆ degradation. The electrolyte introduced in the protective layer remains within the coating layer after solvent removal and acts as an ion transport channel at the interface. This enables the protective layer to exhibit high ionic conductivity and mechanical strength. The composite protective layer, which exhibits synergistic soft‐rigid characteristics, is placed on the Li metal anode and facilitates superior interfacial stability during long‐term cycles. LiMn₂O₄/coated lithium full cells using the composite protective layer show a superior rate capability and enhanced capacity retention compared to the cells using a bare lithium anode. The proposed strategy opens new avenues to fabricate a sustainable composite protective layer that affords superior performance in lithium metal batteries.