A research team led by Prof. 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. The technology has achieved world-class energy efficiency, fully charging a commercial battery within two hours, even inside the human body.
Recently, a rise in an aging population, diseases, and accidents has driven an increase in demand for implantable medical devices (e.g., pacemakers and neural stimulators). 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, 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 percent greater efficiency compared to that of conventional designs.
Using this technology, the research team demonstrated that a 140 mAh commercial battery could be fully charged in just one hour and 40 minutes at an underwater distance of 30 mm. In another experiment using 30-mm-thick pig tissue, a 60 mAh 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.
“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,” Chang says.
This research was supported by the Ministry of Science and ICT through the Future Pioneering Convergence Science and Technology Development Project (formerly known as the STEAM Research Program). Results of the study were published in Biosensors and Bioelectronics.
For more information, contact Jin Ho Change at
