SUMMARY

Acoustic power transfer, or ultrasonic power transfer (UPT) more specifically, has received growing attention as a viable approach for wireless power delivery to low-power electronic devices. It has found applications in powering biomedical implants, sensors in sealed metallic enclosures, and sensors deep in the ocean. The design of an efficient UPT system requires coupled multiphysics modeling to establish strategies toward maximizing the transferred power. This work, first, investigates different analytical and numerical models to analyze the performance of UPT systems. Various electromechanical models are developed to represent transducers with a broad range of aspect ratios. The main challenges that limit UPT system efficiency such as attenuation, power divergence, and reflection due to impedance mismatch issues are investigated using the developed models. A complete system for transferring power through metals from a battery to a DC load is designed and simulated, then experimentally tested. The experimental results of the system with bonded transducers agree well with the modeling predictions, and the system delivers 17.5W to a DC load with a total DC-to-DC efficiency of 66%. A second system with a portable and detachable dry-coupled transmitter is also experimentally tested. The dry-coupled system delivers 3W of DC power with 50% efficiency from a 9V battery. Novel approaches using acoustic metamaterials/phononic crystals are introduced to enhance the efficiency of UPT through wave focusing. Specifically, two 3D phononic crystal structures based on air in a 3D-printed polymer matrix are introduced to manipulate acoustic waves both under water and in air. Two designs for gradient-index lenses are fabricated and experimentally characterized to focus acoustic waves on a piezoelectric receiver, thereby dramatically enhancing the power output. Finally, acoustic and electrical impedance matching are investigated for sending both power and data using ultrasonic waves. Several impedance matching techniques are proposed to maximize transducer bandwidth, power efficiency, as well as sensitivity for underwater data transfer. These techniques are also leveraged to achieve simultaneous power and data transfer using a single transducer through frequency multiplexing. Online link: https://bluejeans.com/297031140/4516?src=calendarLink