Investigation of self-actuated hydrogel-elastomer hybrid sheets at the air-water interface using numerical simulation method

Active hydrogel-elastomer hybrid sheets suspended at the fluid interface (e.g., air-water) exhibit interesting shape morphing behaviors when self-actuated. Incorporating temperature-responsive poly(N-isopropylacrylamide) (PNIPAM) hydrogels with the passive polydimethylsiloxane (PDMS) elastomers, we construct thin hybrid sheets with controllable geometric designs that self-actuate at the air-water interface by the decreased water temperature below the LCST condition. Through numerical simulation approach. this study aims to investigate the positive and negative Gaussian curvatures emerging from the suspended hydrogel-elastomer sheets at the air-water interface. The effect of variations in initial sheet geometries such as sheet thickness, concentric radii, and overall geometric shapes to the fully actuated curvatures were qualitatively analyzed. Our numerical study showcases that employing the hydrogel-elastomer hybrid systems under physical constraints like suspension at air-water interfaces can lead to interesting shape actuation capabilities, which can be extended to new design insights for self-actuating applications in soft robotics, biomedical devices, etc.