Typical pneumatic soft micro actuators can be created without the use of heavy driving components like pumps and power supplies by using an independent battery-powered mechanism. The fabrication of a thermopneumatically operated soft micro bellows actuator and its experimentally proven standalone operation are presented in this study. Thermopneumatic actuation works by heating a compartment sealed by the actuator’s elastomer to increase pressure, which causes the elastomer to deflect. To eliminate leakage, which is prevalent in soft lithography due to individual layer bonding, the bellows actuator was created by casting polydimethylsiloxane (PDMS) using a 3D-printed soluble mould method. A heater constructed separately from winding copper wire was inserted into the cavity of the bellows actuator to make a thermopneumatic actuator. The use of both a 3D coil heater and a bellows actuator allowed for fast heat transfer as well as unrestricted movement of the actuator in the desired direction, which is impossible to do with traditional microfabrication. At a voltage of 0.55 V, the manufactured actuator produced a stroke of around 2200 m, or 62 percent of its body length, and exerted a force of roughly 90 mN. The thermopneumatic actuator was also able to demonstrate a repeating freestanding operation using the system consisting of alkaline batteries and a control circuit, rather than the traditional pneumatic operation.
Department of Control and Instrumentation Engineering, Korea University, Sejong Campus, Republic of Korea.