Hybrid resonant energy harvester integrating ZnO NWs with MEMS for enabling zero-power wireless sensor nodes

This work introduces a novel concept for energy scavenging from ambient vibrations utilizing ZnO nanowires (NWs). This concept relies on the combination into a single device of a resonant element (i.e. an inertial mass suspended by four serpentine springs) and two arrays of NWs grown at both sides of the inertial mass. The NWs can be bent as a result of the resonant motion of the mass. Due to the zigzag-shaped profile of the inertial mass, this bending generates an electric current between the electrodes. This power can be used to supply wireless sensor nodes at the micro and nanoscale level. In addition, this generator can be integrated with other elements that can be achieved by taking advantage of the ZnO NWs and their unique properties such as chemical sensors, optoelectromechanical systems or logic circuits driven by mechanical or optical signals. A detailed fabrication process, containing the NW growth method, is described in this paper. Theoretical calculations and FEM simulations have been performed and show the possibility of using these kinds of devices to scavenge energy from sonic and ultrasonic waves.