Principles, Development History, and Future Prospects of Underwater Ultrasonic Wireless Power Transfer Technology

With the continuous advancement of ocean exploration and development, energy supply for underwater electronic equipment has become a key bottleneck restricting long-term operation. Traditional wired power supply and battery-powered operation suffer from corrosion, high maintenance costs, limited endurance, and replacement difficulties. Underwater ultrasonic wireless power transfer (UUWPT) achieves contactless electric–acoustic–electric conversion via piezoelectric transducers. It offers unique advantages, including insensitivity to electromagnetic interference, metal-penetration capability, excellent directivity, and medium-to-long-distance transmission. This paper systematically reviews the technical principles and development history of UUWPT. We trace its evolution from early feasibility verification, through theoretical improvements, to current system engineering and industrialization. Key frontier research directions are highlighted, such as MIMO/MISO arrays, simultaneous wireless power and data transfer (SWPDT), adaptive tuning, and novel transducer structures. Application prospects in marine monitoring, AUV endurance replenishment, marine energy development, and the Internet of Underwater Things are also analyzed. Finally, we discuss remaining challenges, including the trade-off between transmission efficiency and distance, insufficient adaptability to complex marine environments, and the lack of standardized system frameworks. Future research should prioritize high-efficiency long-distance power transfer, system reliability, and engineering applications.