Constructing Anisotropic Conductive Networks inside Hollow Elastic Fiber with High Sensitivity and Wide‑Range Linearity by Cryo‑spun Drying Strategy

Stretchable conductive fibers composed of conductive materials and elastic substrates have advantages such as braiding abil-ity,electrical conductivity,and high resilience,making them ideal materials for fibrous wearable strain sensors.However,the weak interface between the conductive materials and elastic substrates restricts fibers flexibility under strain,leading to challenges in achieving both linearity and sensitivity of the as-prepared fibrous strain sensor.Herein,cryo-spun drying strategy is proposed to fabricate the thermoplastic polyurethane(TPU)fiber with anisotropic conductive networks(ACN@TPU fiber).Benefiting from the excellent mechanical properties of TPU,and the excellent interface among TPU,silver nanoparticles(AgNPs)and polyvinyl alcohol(PVA),the prepared ACN@TPU fiber exhibits an outstanding mechanical performance.The anisotropic conductive networks enable the ACN@TPU fiber to achieve high sensitivity(gauge factor,GF=4.68)and excellent linearity within a wide working range(100%strain).Furthermore,mathematical model based on AgNPs is established and the resistance calculation equation is derived,with a highly matched fitting and experimental results(R2=0.998).As a conceptual demonstration,the ACN@TPU fiber sensor is worn on a mannequin to accurately and instantly detect movements.Therefore,the successful construction of ACN@TPU fiber with anisotropic conductive networks through the cryo-spun drying strategy provides a feasible approach for the design and preparation of fibrous strain sensing materials with high linearity and high sensitivity.

A review of methods for evaluating effectiveness of cosmetic products and ingredients based on mechanisms of the human hair growth cycle

With the increasing incidence of hair loss and especially among younger population in recent years,the demand for diversified products on anti-hair loss solutions is growing and the market of cosmetic products expanding accordingly.Worldwide attention is being paid to the research and development of anti-hair loss actives,while there is no unified standard for the efficacy evaluation and testing methods of anti-hair loss cosmetics.Therefore,it is critical to establish standardized methodology for assessing the effectiveness of anti-hair loss actives and their cosmetic products.In this review,an overview of the human hair follicle structure,the hair follicle cycle,and the biological pathways and signaling mechanisms involved in hair growth are summarized.This provides the fundamental understanding of human hair growth for reviewing anti-hair loss actives and cosmetic hair loss products,and respective methods and techniques applied for evaluating their efficacy.Additionally,changes in the normal hair cycle,and corresponding cosmetic strategies to slow down and reduce hair loss have been provided.This review aims to provide recommendations for evaluating the effectiveness of anti-hair loss actives on the mechanisms involved in the hair follicle growth cycle,and so provide criteria for new technology development and scientific research for cosmetic products.

Dense Hydrogen-Bonding Network Boosts Ionic Conductive Hydrogels with Extremely High Toughness,Rapid Self-Recovery,and Autonomous Adhesion for Human-Motion Detection

The construction of ionic conductive hydrogels with high transparency,excellent mechanical robustness,high toughness,and rapid self-recovery is highly desired yet challenging.Herein,a hydrogen-bonding network densification strategy is presented for preparing a highly stretchable and transparent poly(ionic liquid)hydrogel(PAM-r-MVIC)from the perspective of random copolymerization of 1-methyl-3-(4-vinylbenzyl)imidazolium chloride and acrylamide in water.Ascribing to the formation of a dense hydrogen-bonding network,the resultant PAM-r-MVIC exhibited an intrinsically high stretchability(>1000%)and compressibility(90%),fast self-recovery with high toughness(2950 kJ m^(-3)),and excellent fatigue resistance with no deviation for 100 cycles.Dissipative particle dynamics simulations revealed that the orientation of hydrogen bonds along the stretching direction boosted mechanical strength and toughness,which were further proved by the restriction of molecular chain movements ascribing to the formation of a dense hydrogen-bonding network from mean square displacement calculations.Combining with high ionic conductivity over a wide temperature range and autonomous adhesion on various surfaces with tailored adhesive strength,the PAM-r-MVIC can readily work as a highly stretchable and healable ionic conductor for a capacitive/resistive bimodal sensor with self-adhesion,high sensitivity,excellent linearity,and great durability.This study might provide a new path of designing and fabricating ionic conductive hydrogels with high mechanical elasticity,high toughness,and excellent fatigue resilience for skin-inspired ionic sensors in detecting complex human motions.

受关节软骨启发的耐疲劳和耐苛刻环境的三维超弹海绵导体

海绵导体在承受极端压缩和恶劣环境时,面临着机械脆性和导电网络易发生不可逆破坏等瓶颈.发展轻质、超弹和耐疲劳的海绵导体具有非常重要的研究和应用前景.本论文提出表面受限雾化水模板策略,获得了聚合物海绵骨架承载蜂窝状碳纳米管的新型海绵导体(h-SCNTC).通过借鉴在反复形变下具有梯度能量耗散机制的关节软骨结构,h-SCNTC展现出可快速恢复的压缩回弹性能(宽的压缩应变范围:0–90%)以及高的抗疲劳性(5000次循环后海绵高度保持率>95%).归因于在低压缩应变下骨架表面蜂窝状导电结构的“连通-断开”机制和在高压缩应变下海绵导电骨架“形变-接触”机制的结合,所得压阻传感器展现出超弹性、高稳定性和在宽应变范围内(0–90%)具有高灵敏度等卓越特征.该海绵导体能够有效抑制环境中水的侵蚀作用,在极端湿度和机器洗涤等恶劣环境中仍能保持耐久性.本研究提出的表面受限雾化水模板策略,有望为制备超弹性耐疲劳海绵导体及其耐变形电子设备提供新的思路.