Applying IPMC to soft robots

Soft robots have a great potential for realizing human-friendly robots with adaptability and gentleness. An actuator is a crucial element for realizing them; various types of soft actuators have been developed, such as pneumatic actuators and polymer actuators. We have focused on ionic polymer metal composites (IPMC), and applied them to soft robots. In this paper, new design and fabrication processes are presented with several examples of soft actuators/robots developed in our lab. Two topics are shown in this paper. The first one is a hose-free pneumatic actuator driven by gas/liquid chemical reaction through the IPMC membrane. The pneumatic or gas-driven actuators are one of the most promising actuators in soft robotics. However, they need airsupply hoses, valves, and gas sources, which makes their work as mobile or portable actuators difficult. We have applied the IPMC membrane to control water electrolysis/synthesis, where IPMC works as an ion-exchange membrane. It controls the gas pressure and drives air-driven actuators without a hose. Two examples are shown in this paper— electrically driven thin McKibben muscles and tether-less pneumatic robots. The second topic is on IPMC actuators/robots with various 3D shapes. Most of the previous robots driven by IPMC actuators have been made by cutting and assembling the IPMC sheets, or they are very simple robots for the demonstration of IPMC actuators. Two design and fabrication processes developed in our lab to realize soft robots with arbitrary 3D structures are discussed in this paper, which are multi-layer casting and paper/fabric assisted IPMC actuators or PF-IPMC process.