Dual-Ion Co-Regulation System Enabling High-Performance Electrochemical Artificial Yarn Muscles with Energy-Free Catch States

Artificial yarn muscles show great potential in applications requiring low-energy consumption while maintaining high performance. However, conventional designs have been limited by weak ion-yarn muscle interactions and inefficient “rocking-chair” ion migration. To address these limitations, we present an electrochemical artificial yarn muscle design driven by a dual-ion co-regulation system. By utilizing two reaction channels, this system shortens ion migration pathways, leading to faster and more efficient actuation. During the charging/discharging process, PF_6~- ions react with carbon nanotube yarn, while Li~+ ions react with an Al foil. The intercalation reaction between PF_6~- and collapsed carbon nanotubes allows the yarn muscle to achieve an energy-free high-tension catch state. The dual-ion coordinated yarn muscles exhibit superior contractile stroke, maximum contractile rate, and maximum power densities, exceeding those of “rocking-chair” type ion migration yarn muscles. The dual-ion co-regulation system enhances the ion migration rate during actuation, resulting in improved performance. Moreover, the yarn muscles can withstand high levels of isometric stress, displaying a stress of 61 times that of skeletal muscles and 8 times that of “rocking-chair” type yarn muscles at higher frequencies. This technology holds significant potential for various applications, including prosthetics and robotics.

Hollow Gradient-Structured Iron-Anchored Carbon Nanospheres for Enhanced Electromagnetic Wave Absorption

In the present paper,a microwave absorber with nanoscale gradient structure was proposed for enhancing the electromagnetic absorption performance.The inorganic-organic competitive coating strategy was employed,which can effectively adjust the thermodynamic and kinetic reactions of iron ions during the solvothermal process.As a result,Fe nanoparticles can be gradually decreased from the inner side to the surface across the hollow carbon shell.The results reveal that it offers an outstanding reflection loss value in combination with broadband wave absorption and flexible adjustment ability,which is superior to other relative graded distribution structures and satisfied with the requirements of lightweight equipment.In addition,this work elucidates the intrinsic microwave regulation mechanism of the multiscale hybrid electromagnetic wave absorber.The excellent impedance matching and moderate dielectric parameters are exhibited to be the dominative factors for the promotion of microwave absorption performance of the optimized materials.This strategy to prepare gradient-distributed microwave absorbing materials initiates a new way for designing and fabricating wave absorber with excellent impedance matching property in practical applications.

A multifunctional flexible sensor based on PI-MXene/SrTiO_(3) hybrid aerogel for tactile perception

The inadequacy of tactile perception systems in humanoid robotic manipulators limits the breadth of available robotic applications.Here,we designed a multifunctional flexible tactile sensor for robotic fingers that provides capabilities similar to those of human skin sensing modalities.This sensor utilizes a novel PI-MXene/SrTiO_(3) hybrid aerogel developed as a sensing unit with the additional abilities of electromagnetic transmission and thermal insulation to adapt to certain complex environments.Moreover,polyimide(PI)provides a high-strength skeleton,MXene realizes a pressure-sensing function,and MXene/SrTiO_(3) achieves both thermoelectric and infrared radiation response behaviors.Furthermore,via the pressure response mechanism and unsteady-state heat transfer,these aerogel-derived flexible sensors realize multimodal sensing and recognition capabilities with minimal cross-coupling.They can differentiate among 13 types of hardness and four types of material from objects with accuracies of 94%and 85%,respectively,using a decision tree algorithm.In addition,based on the infrared radiation-sensing function,a sensory array was assembled,and different shapes of objects were successfully recognized.These findings demonstrate that this PI-MXene/SrTiO_(3) aerogel provides a new concept for expanding the multifunctionality of flexible sensors such that the manipulator can more closely reach the tactile level of the human hand.This advancement reduces the difficulty of integrating humanoid robots and provides a new breadth of application scenarios for their possibility.

A machine learning-assisted multifunctional tactile sensor for smart prosthetics

The absence of tactile perception limits the dexterity of a prosthetic hand and its acceptance by amputees.Recreating the sensing properties of the skin using a flexible tactile sensor could have profound implications for prosthetics,whereas existing tactile sensors often have limited functionality with cross-interference.In this study,we propose a machine-learning-assisted multifunctional tactile sensor for smart prosthetics,providing a human-like tactile sensing approach for amputations.This flexible sensor is based on a poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS)-melamine sponge,which enables the detection of force and temperature with low cross-coupling owing to two separate sensing mechanisms:the open-circuit voltage of the sensor as a force-insensitive intrinsic variable to measure the absolute temperature and the resistance as a temperature-insensitive extrinsic variable to measure force.Furthermore,by analyzing the unsteady heat conduction and characterizing it using real-time thermal imaging,we demonstrated that the process of open-circuit voltage variation resulting from the unsteady heat conduction is closely correlated with the heatconducting capabilities of materials,which can be utilized to discriminate between substances.Assisted by the decision tree algorithm,the device is endowed with thermal conductivity sensing ability,which allows it to identify 10 types of substances with an accuracy of 94.7%.Furthermore,an individual wearing an advanced myoelectric prosthesis equipped with the above sensor can sense pressure,temperature,and recognize different materials.We demonstrated that our multifunctional tactile sensor provides a new strategy to help amputees feel force,temperature and identify the material of objects without the aid of vision.

Thermally driven carbon nanotube@polycaprolactone coaxial artificial muscle fibers working in subzero environments

Artificial muscle fibers driven electrothermally with excellent properties of response,stroke,and work capacity are expected to serve in some intelligent structures and systems.However,muscle fibers that operate in subzero environments are highly needed in industrial production and aerospace applications but remain challenging.Herein,we reported a coaxial artificial muscle fiber by electrospinning a sheath of polycaprolactone(PCL)nanofibers on the surface of a carbon nanotube(CNT)fiber core,achieving the actuation in response to thermal at subzero temperatures.The CNT@PCL coaxial muscle fiber under 0.3 MPa achieved a maximum contractile stroke of~18%as the temperature changed from−130℃ to 45℃.The actuation mechanism at subzero temperatures of this muscle fiber was analyzed in combination with the temperature-deformation schematic curve of different polymers.Furthermore,a temperature sensor based on this muscle fiber was developed,due to the excellent linear relationship between the contraction and temperature.A 3D-printed prosthetic arm was designed to further exhibit the application demonstrations of this muscle fiber in subzero environments.This work provides new insights into artificial muscle fibers for serving in extreme environments with ultralow temperatures.

Fast Zn^(2+)mobility enabled by sucrose modified Zn^(2+)solvation structure for dendrite-free aqueous zinc battery

Aqueous zinc battery has been regarded as one of the most promising energy storage systems due to its low cost and environmental benignity.However,the safety concern on Zn anodes caused by uncontrolled Zn dendrite growth in aqueous electrolyte hinders their application.Herein,sucrose with multi-hydroxyl groups has been introduced into aqueous electrolyte to modify Zn^(2+)solvation environment and create a protection layer on Zn anode,thus effectively retarding the growth of zinc dendrites.Atomistic simulations and experiments confirm that sucrose molecules can enter into the solvation sheath of Zn^(2+),and the as-formed unique solvation structure enhances the mobility of Zn^(2+).Such fast Zn^(2+)kinetics in sucrose-modified electrolyte can successfully suppress the dendrite growth.With this sucrose-modified aqueous electrolyte,Zn/Zn symmetric cells present more stable cycle performance than those using pure aqueous electrolyte;Zn/C cells also deliver an impressive higher energy density of 129.7 Wh·kg^(−1)and improved stability,suggesting a great potential application of sucrose-modified electrolytes for future Zn batteries.

Carbon nanotube fibers with excellent mechanical and electrical properties by structural realigning and densification

Floating catalysis chemical vapor deposition(FCCVD)direct spinning process is an attractive method for fabrication of carbon nanotube fibers(CNTFs).However,the intrinsic structural defects,such as entanglement of the constituent carbon nanotubes(CNTs)and inter-tube gaps within the FCCVD CNTFs,hinder the enhancement of mechanical/electrical properties and the realization of practical applications of CNTFs.Therefore,achieving a comprehensive reassembly of CNTFs with both high alignment and dense packing is particularly crucial.Herein,an efficient reinforcing strategy for FCCVD CNTFs was developed,involving chlorosulfonic acid-assisted wet stretching for CNT realigning and mechanical rolling for densification.To reveal the intrinsic relationship between the microstructure and the mechanical/electrical properties of CNTFs,the microstructure evolution of the CNTFs was characterized by cross-sectional scanning electron microscopy(SEM),wide angle X-ray scattering(WAXS),polarized Raman spectroscopy and Brunauer–Emmett–Teller(BET)analysis.The results demonstrate that this strategy can improve the CNT alignment and eliminate the inter-tube voids in the CNTFs,which will lead to the decrease of mean distance between CNTs and increase of inter-tube contact area,resulting in the enhanced inter-tube van der Waals interactions.These microstructural evolutions are beneficial to the load transfer and electron transport between CNTs,and are the main cause of the significant enhancement of mechanical and electrical properties of the CNTFs.Specifically,the tensile strength,elastic modulus and electrical conductivity of the high-performance CNTFs are 7.67 GPa,230 GPa and 4.36×10^(6)S/m,respectively.It paves the way for further applications of CNTFs in high-end functional composites.

High‑Temperature‑Tolerant Artificial Muscles Using Poly(p‑phenylene benzobisoxazole)Composite Yarns

Today the developed yarn muscles or actuators still cannot satisfy the requirements of working in high-temperature environ-ments.Thermal resistivity is highly needed in aerospace and industrial protection applications.Herein,an artificial muscle with high-temperature tolerance is prepared using carbon nanotube(CNT)wrapped poly(p-phenylene benzobisoxazole)(PBO)composite yarns.A thermal twisting method was utilized to reorientate the stiff PBO molecular chains into a uniform and twist-stable coiled structure.The CNT/PBO composite yarn muscle generates reversible contractile strokes up to 18.9%under 5.4 MPa tension and outputs 1.3 kJ kg^(-1) energy density.In contrast to previous actuators,which are normally oper-ated at room temperatures,the CNT/PBO composite yarn muscles can work at ambient temperatures up to 300℃ with high contractile stroke and long-term stability.A bionic inchworm robot,a deployable structure,and smart textiles driven by the high-temperature-tolerant yarn muscles were demonstrated,showing the promise as a soft actuator towards high-temperature environment applications.