Ionic Electroactive Polymers Used in Bionic Robots： A Review

Ionic electroactive polymers （IEAPs） are a category of intelligent soft materials exhibiting large displacement under electric excitation, based on inner ion or solvent transport. Due to their unique advantages such as flexibility, low driving voltage, large bending displacement and aquatic-environment adaptability, IEAPs have been documented as very promising actuators for the applications in bionic robots. This review presents an analysis to the current research status of IEAPs exploited in bionic robots. According to the specific bionic parts, those robots are divided into four classes： imitation of fins, limbs, joints and trunks. Their dimension, weight, voltage amplitude, frequency and maximum speed were summarized to show the optimum design range. The results show that the approach velocity of the current robots were higher （〉 35 mm· s-1） when the robot weighted 60 g - 180 g and the body was 90 mm - 130 mm long. For voltage from 1 V - 3 V and frequencies from 0.7 Hz - 1.2 Hz, the speed was relatively higher （〉 35 mm·s-1）.To some extent, the maximum speed decreases when the area of the IEAP material used in bionic robot increases. For underwater circumstances, IEAP materials are most suitable for designing bionic robots swimming with Body and/or Caudal Fin （BCF）. This review provides important guidance for the design of lEAP bionic robots.

Integrated fabrication process with multiple optimized factors for high power density of IPMC actuator

Ionic polymer-metal composites(IPMCs)are typical smart mate-rials that are commonly used in bionic applications,including soft robots,bionic flapping aircraft,and bionic fish.However,their low output force seriously limits device performance.Stacking of multiple IPMC actuators to improve the overall performance of soft actuators is a strategy that is used in practical applications.Under the energy dissipation condition in the IPMC stacking structure,if each single IPMC in the struc-ture has high power density,the structure will produce excel-lent performance with high efficiency that can greatly promote wider application of IPMC actuators.To meet this requirement,a method for fabrication process integration with multiple opti-mized factors was used to obtain IPMC materials in this paper.Carbon nanotube(CNT)doping,isopropyl alcohol-assisted plat-ing,and hot pressing with a mesoscopic structural mold were selected as typical optimization methods for process integration and were initially investigated separately to determine the opti-mal process parameters.By combining the best process para-meters in an integrated process,the IPMC treated by isopropyl alcohol-assisted plating and CNT doping process(No.AC7)showed excellent actuation performance and high work density(~9.71/12.36 gf,~14.93/31.89 kJ/m^(3) under 3/4 VDC).The enhanced performance meets the requirements for practical bionic applications.