Abstract: This paper presents the design and analysis of an osmosis-based artificial muscle inspired by the leaf movements of Mimosa pudica. M. pudica’s leaves quickly contract using osmosis pressure in the pulvinus when they are stimulated. We analyzed and simulated an osmosis system to identify the factors for fast osmosis reactions and designed a prototype artificial muscle based on the results. The osmosis phenomenon was mathematically modeled, analyzed, and verified through several experiments. The analysis shows that fast osmosis responses require a large diffusion coefficient with a high-flux membrane or small ratio of the cross-sectional area to the volume of the osmosis system. We designed a micro-scale system to achieve the required ratio. The contraction and relaxation of the artificial muscle are realized by changes of the local concentration of potassium ions, which can be aggregated by a controllable electric field. As a result, the artificial muscle shows controllable behavior with fast reactions.

Key words: Mimosa pudica, osmosis, artificial muscle, cross-sectional area to volume ratio, micro-scale