Conformably Skin-Adherent Piezoelectric Patch with Bioinspired Hierarchically Arrayed Microsuckers Enables Physical Energy Amplification

An intimate contact interface between wearable energy harvesting devices and nonflat human surfaces is critical for harvesting energy from the body's movements. The device can only absorb the deformation strain under stable interfacial adhesion to biological surfaces. Past developments have mainly examined the active layer of such devices, but the device/body adhesive interface effects are rarely considered. Here, we introduce a hierarchically arrayed octopus-inspired pattern (h-OP) formed on piezoelectric composite patch devices. The h-OP enables robust wet adhesion to skin because its dome-like architecture achieves interfacial adhesion by generating cohesive forces among liquid molecules. We used finite element method simulation to investigate decohesion behaviors with bending-induced stress distribution. The enhanced adhesion provided efficient energy generation under strain according to body movements. With 90° wrist bending, the h-OP devices demonstrated approximately triple the energy generation of implementations with no pattern, exhibiting stable adhesion and high energy generation efficiency, even on the wet skin.