Soft fiber-reinforced bending finger with three chambers actuated by ECF (electro-conjugate fluid) pumps

Abstract Fluidic elastomer actuators (FEAs) have been used for various purposes such as grippers, soft robots, artificial muscles etc. A major challenge for the FEAs is their big and cumbersome power sources, which include valves, regulators, hydraulic pumps and air cylinders. Therefore, we integrated an ECF jet generator (a hydraulic pressure source) into a soft fiber-reinforced bending tube with three chambers. ECF (electro-conjugate fluid) is a kind of functional and dielectric fluid, which can generate a strong and active ECF jet when a high DC voltage is applied to its corresponding anode & cathode in ECF. The ECF jet generator has three ECF pumps with three pairs of electrodes, namely, needle-ring electrodes, which are manufactured by machining. The flexible tube consists of three soft chambers fabricated by replicating the molds. The principle is that one chamber (two chambers) of the soft finger expands as the inner pressure is generated by the ECF pump and two other chambers (one chamber), acting as an ECF container, shrinks, which finally causes the finger to bend. We introduce two types of commonly used ECFs and investigate their impact on the soft fiber-reinforced bending finger. Then, we numerically simulate the pressure generated by the ECF generator and the displacement of the bending finger, which are validated by the experiments. Finally, we research the dynamic performance of the bending finger. The work contributes to the miniaturization of power sources in the field of soft robots with spatial motions and is also helpful for the development of other ECF-based soft robots.