Manufactured laminated piezoelectric element-based ultrasonic harvester (SW-PUSH). Credit: Manufactured laminated piezoelectric element-based ultrasonic harvester (SW-PUSH). Biosensors and Bioelectronics (2025). DOI: 10.1016/j.bios.2025.117789
A research team led by Professor Jinho Chang from the Department of Electrical Engineering and Computer Science at DGIST has developed an "ultrasound-based wireless charging technology" capable of rapidly and efficiently charging the batteries of implantable medical devices. This technology has achieved world-class energy efficiency, fully charging a commercial battery within two hours, even inside the human body.
The research is published in the journal Biosensors and Bioelectronics.
Recently, due to population aging, diseases, and accidents, a rapid increase in demand for implantable medical devices (e.g., pacemakers and neural stimulators) has been observed. However, the batteries in these devices must be replaced periodically, requiring patients to undergo repeated surgeries—posing both inconveniences and risks. To address this issue, developing technology that can wirelessly transmit energy from outside the body is essential in order to charge the batteries without the need for additional surgeries.
Although wireless charging technologies using ultrasound have existed previously, harvesters (energy receivers) that can be implanted in the human body have faced limitations in size and structure. Additionally, the ultrasound intensity that can be safely used in the human body is restricted, resulting in insufficient power output.
To overcome these limitations, Professor Chang's research team at DGIST developed a new type of "sandwich-structured piezoelectric energy harvester." Two piezoelectric layers are stacked such that the front layer harvests incoming ultrasound energy to generate electricity, while the rear layer captures the residual ultrasound to produce additional power. By combining the output from both layers, the harvester achieves over 20% greater efficiency compared to that of conventional designs.
Using this technology, the research team demonstrated that a 140mAh commercial battery could be fully charged in just one hour and 40 minutes at an underwater distance of 30mm. In another experiment using 30mm-thick pig tissue, a 60mAh battery was fully charged within one hour and 20 minutes. These results represent a world-leading performance, achieving at least twice the power output of previously reported technologies.
Professor Chang stated, "This research presents an innovative technology that effectively harvests ultrasound energy, which has not been fully utilized in the past, for wireless charging of implantable medical devices. We aim to commercialize a system capable of fully charging within one hour by combining this ultrasound-based wireless charging technology with high-efficiency semiconductor components."
Provided by Daegu Gyeongbuk Institute of Science and Technology