Stretchable, Skin-Adherent Piezoelectric Patch with Hierarchically Bio-Inspired Architectures for Energy Amplification

Recently, the piezoelectric energy harvester with advantages including high-power density, simple design, and high scalability under low strain changes has emerged as an alternative to supply electrical energy to intelligent technologies such as wearable healthcare electronics, robots, and biomedical devices. However, the low adhesion between the wearable energy harvesting device and the biological skin interface has limited its ability to generate electrical energy from physical movements of the body. Here, we report a Stretchable skin-adherent piezoelectric patch with a hierarchically designed octopus-beetle inspired array (HOBA). HOBA is composed of adhesion layer, stretchable electrode, and piezoelectric energy composite. Each layer is based on a polymer material, which helps HOBA to be monolithic and has excellent mechanical stability between layers. The adhesion layer has high normal adhesion and shear adhesions in rough skin. Stretchable electrodes with a wrinkle structure show stable electrical conductivity even in omnidirectional stretching and bending. The energy composite layer is based on a lead-free material that can be used on the human body and has a constant power density of 1.52 W/cm³ in repeated bending (150°). Finally, our energy patch shows potential for use as a self-powered sensor for monitoring muscle movement and finger movement for medical applications.