The transformation of ambient mechanical energy such as vibrational energy into low-power electricity for enabling self-powered wireless electronic components has been heavily investigated over the last decade. This method of energy transfer is possible as long as sufficient ambient energy is readily available in the vicinity of small devices. There are several conditions where there is no ambient energy available or battery replacement or tethered charging is either undesirable or impossible, for example, deep-implanted medical devices or sensors located in hazardous environments such as nuclear waste containers. In such cases, contactless power transfer is needed. The primary objective of this theoretical and experimental research is to perform a system-level investigation of contactless ultrasonic power transfer dynamics to lay the foundation for its implementation in next-generation wireless devices. One particular method of contactless power transfer that has lately received growing attention is the use of ultrasound waves (which are acoustic waves with frequencies higher than the human hearing range). The use of ultrasound offers several advantages such as relatively long power transmission distances using smaller transducers, and elimination of magnetic fields, as compared to popular power transfer methods such as inductive coupling. The research has significant potential for technological and broad societal impact. Contactless powering of wireless electronic components can reduce the maintenance costs in sensor networks and chemical waste of discarded batteries. Wireless charging of deep-implanted medical devices can eliminate the surgery-related complications associated with battery replacement. The project involves efforts to recruit women and minority undergraduate students and involvement of high school teachers in research experience.
The effective use of ultrasonic power transfer as an enabling technology in wireless applications faces difficult challenges due to the presence of obstacles, reflections, diffractions, losses, and acoustic or electromechanical impedance matching issues resulting from the multiple domains involved. The objective of this research program is to perform a system-level theoretical and experimental investigation of contactless ultrasonic power transfer by coupling the dynamics of electromechanical systems, piezoelectricity, ultrasonic wave physics, and acoustic metamaterials. The project will generate a comprehensive knowledge of the underlying multiphysics dynamics to be exploited in next-generation wireless electronic devices spanning from medical implants to remote sensors with no direct physical access. System-level, experimentally validated, high-fidelity multiphysics modeling frameworks that combine transmitter-receiver-electrical load dynamics with acoustic propagation across multiple domains can enable the design of efficient ultrasonic power transfer systems. Additionally, concepts from phononic crystals and metamaterials can be exploited for combined wave focusing and impedance matching, and phased arrays can be leveraged for obstacle circumventing in power transfer. The specific research goals are to (1) establish fully coupled modeling frameworks to analyze multiphysics dynamics of contactless ultrasonic power transfer; (2) leverage various piezoelectric transmitter-receiver architectures including phased arrays; and (3) exploit phononic crystals and metamaterials for combined wave focusing and impedance matching.