Skin-like Elastomer Embedded Zinc Oxide Nanoarrays for Biomechanical Energy Harvesting

Energy harvesting (EH) technologies have been rapidly developed to replace the batteries of biomechanical electronics, but efforts are still needed to close the technology gaps in achieving flexible and biocompatible energy harvesters. Current flexible energy harvesters based on ZnO nanoarrays require complex fabrication processes, and they are non-stretchable as they are usually fabricated on hard substrates. In this work, a facile approach is reported for fabricating a substrate-free energy harvester with ZnO nanoarrays directly and fully embedded in a skin-like polydimethylsiloxane (PDMS) elastomeric matrix that shares a similar mechanical property with that of human skin. The flexible device, with an elastic modulus of 3.3 MPa, can be stretched to 250% of its original length, generates an open-circuit voltage up to 9.2 V_pp and power LEDs from finger-hand motions. Further, the device collects energy from hand-finger motions and heartbeats through ex and in vivo tests. A ≈0.3 V_pp open circuit voltage is generated from the device installed on a leadless pacemaker in a porcine model. This work suggests a generic design strategy that overcomes the mechanical mismatch between the energy materials and soft tissues for a wide range of biomechanical EH applications from wearables to implantable ones.