A Flexible ER Microactuator Using Homogeneous Electro-Rheological Fluid

Abstract

The paper proposed and developed a flexible ER microactuator called FERMA for in-pipe working micromachines, medical micro robots, and so on. An ER microvalve has a narrow flow channel with electrodes and controls flow of homogeneous electro-rheological (ER) fluid using the apparent viscosity change in an electric field. A conventional ER microactuator that consists of the ER microvalve and a fluid microactuator features simple structure, however, it is difficult to realize a flexible actuator due to the rigidity of the ER microvalve having sufficient channel length for pressure drop. To overcome the problem, we proposed an FERMA having a flexible ER valve called FERV inside a flexible tube. In the proposed FERV, an insulating thin flexible spacer with a slit was sandwiched by a pair of thin electrode sheets and they were wrapped by rubber. The slit in the spacer and two electrode sheets formed a flow channel for an ER valve. In this paper, we fabricated a two-port FERV with 4×3×9 mm3 in size and confirmed the low flexural rigidity and the static characteristics experimentally. Then, we fabricated a three-port FERV and clarified the static and dynamic characteristics experimentally. Finally, we fabricated an FERMA with the three-port FERV and a bellows type flexible tube with 8 mm outside diameter and 8 mm length and investigated experimentally the static and dynamic characteristics in linear and bending motions. The feasibility of the proposed FERMA was demonstrated.