A quick response soft actuator by miniaturized liquid-to-gas phase change mechanism with environmental thermal source

Soft actuators driven by liquid-to-gas phase changes do not require large air pumps or power supply equipment, making them ideal for flexible and compact mechanisms. However, the response time of conventional liquid-to-gas phase change actuators is slow, lasting 10 s. In this study, we proposed a silicone actuator with an improved thermodynamic response by downsizing the actuator to reduce the liquid amount and silicone volume. When placed in hot water at 75 °C, the proposed actuator bends. The wall thickness ratio of the silicone tube and the liquid amount sealed inside could be used to control the bending angle. The proposed actuator’s response time was improved to 1.70 s, close to the theoretical response time. In addition, a liquid replenishment mechanism was installed and evaluated to address the actuator performance degradation caused by gas permeation when elastomers are used. Finally, we demonstrated that the proposed actuator could catch and release an object by combining multiple actuators. We believe the proposed actuator will perform as a tool to efficiently sense external physical changes and convert them into motions in nature.