Modelling and hydrogen-induced stress characterization of hydrogen-driven soft actuator using water splitting

Hydrogen production by water splitting is expected to be a significant power source in future because of its cleanness and environment-friendliness. In this study, an actuator driven by hydrogen produced by water splitting is studied and a hydrogen-induced stress model for a bimorph-type hydrogen actuator is developed. From the examination of the soft actuator having electrodes made of polyvinyl chloride with palladium electrode (Pd-PVC), the stress and bending moment induced by hydrogen absorption during water splitting are quantitatively evaluated. The results show that the thickness of the palladium electrode affects the mechanical performance of the Pd-PVC actuator, with the thinner palladium electrode showing a larger bending moment and tip displacement. A simple mechano-electro-chemical coupling equation is proposed to describe the relationship between bending moment, stress, and the electric charge used for water splitting. A palladium electrode soft actuator can work as a hydrogen generator/storage mechanism and as a mechanical actuator, and it can be useful for the power source of small systems or micro- or nano-devices.