An Omnidirectional MEMS Ultrasonic Energy Harvester for Implanted Devices

This paper presents the design and characterization of a microelectromechanical systems (MEMS)-based energy harvester with target applications, including implanted biomedical sensors and actuators. The harvester is designed to utilize ultrasonic waves from an external transmitter for mechanical excitation, with electrostatic transducers being used to convert the vibrations of a central mass structure into electrical energy. The device features a novel 3-degrees of freedom design, which enables energy to be produced by the harvester in any orientation. The harvester is fabricated using a conventional silicon-on-insulator MEMS process, with experimental testing showing that the system is able to generate 24.7, 19.8, and 14.5 nW of electrical power, respectively, via the device's x-, y-, and z-axis resonance modes over a 15-s period.