Acoustic energy transfer for wireless charging of low-power sensors, control devices, and communication networks

Virginia Polytechnic Institute And State University, Blacksburg VA

Investigators

Abstract

Energy transfer without the use of physical plugs or wires, referred to as contactless energy transfer, is a transformative technology with potentially endless applications. It is particularly relevant in applications where wired electrical contact is dangerous or impractical. Furthermore, it would enhance the development, use and reliability of low-power sensors, control devices and communication networks in applications where wired connections or changing batteries are not practical or may not be a viable option (e.g. medical implants), add to the complexities associated in the systems design and operation (e.g. homes, cars and airplanes) or may pose their own hazards (e.g. fire hazard). As an alternative to the relatively well-studied method of contactless energy transfer, namely the inductive method, ultrasonic acoustic energy transfer, which is based on the propagation of acoustic waves at ultrasonic frequencies to a piezoelectric receiver, offers the potential for wireless charging systems over increased transmitter-receiver distances, with reduced power losses, and elimination of hazards associated with electromagnetic fields. This award supports fundamental research to establish an experimentally-validated mathematical framework for the acoustic-electroelastic dynamics of piezoelectric transmission and reception when subjected to an acoustic medium over broad ranges of low-to-high electrical and acoustic excitation levels. The proposed experiments and analytical multiphysics modeling approach aim at filling a knowledge gap in terms of considering nonlinear effects associated with high excitation levels in ultrasound acoustic energy transfer systems. These effects include the coupled nonlinear acoustic field with non-conservative electroelastic structural responses along with reflections due to impedance mismatch that lead to spatial resonances, energy loss and appearance of higher harmonics during wave propagation in a nonlinear dispersive medium. This research will lead to new understanding of resonant acoustic-piezoelectric systems that will influence the design of ultrasonic acoustic energy transfer systems for various applications -- through innovative mechanisms for wireless charging of low-power sensors by an acoustic-based novel power delivering system, selectively and noninvasively. The research team will provide recommendations at the fundamental level for enhancing system performance through addressing power output for different transducer designs, resistive and resistive-reactive loading, acoustic impedance matching layers, and the material and nonlinearity effects. The output of the research effort will help in the design of optimal acoustic systems that can transfer higher power levels at higher efficiencies in various applications. This project will also reach and inspire a large number of underrepresented and minority students through a complementary and engaging educational plan, prepared in collaboration with Center for Enhancement of Engineering Diversity at Virginia Tech.