Investigation on output-force tremor characteristics of the bionic electric actuator modified by CaCl2 and glycerol

Abstract

Research into output-force tremor characteristics has a major part to play in preventing unstable and inefficient work of biocompatible Bionic Electric Actuator (BEA). Since its output force is small with a scale of mN level, it is susceptible to the surroundings during measurement, and then erratic continuous minor waves are not called the output-force tremor behavior. Precisely, it is defined as the unstable and obvious fluctuations in the BEA output force. In this paper, effects and active mechanisms of CaCl2 cross-linking and doping glycerol on output-force tremor characteristics of the BEA were researched in depth. And its structure was similar to ‘sandwich’, which was made up of the middle electrically actuating membrane made from Sodium Alginate (SA) and bilateral non-metallic electrode membranes blended with Multi-walled Carbon Nanotube (MWCNT). Furthermore, by microscopic picturing, Cyclic Voltammetry (CV) and tensile test, the micro morphology, specific capacitance and elastic modulus of BEA were acquired to clearly clarify its output-force tremor mechanism, and then the control methods were proposed. Experiments revealed that, in the quick growth phase, there was no tremor behavior occurring on the output force, except for a few slight fluctuations. Afterwards, the output force gradually increased and its tremor started to appear frequently, then the amplitude was larger and larger over time. Besides, all the BEA specimens occurred output-force tremors in varying degrees, where they were the slightest at 0.85 g L−1 CaCl2. And as glycerol doping amounts increased, occurrence time of the maximum output force and its tremor was delayed greatly. Thus, by specifying working hours of the BEA, it was applied in the stage of steady growth of the output force before its tremors happening. Generally, our work presents practical approaches to the control of BEA capable of achieving both good output force properties and wide engineering applications.