Ultrasonic wireless charging for implanted medical devices

Korea University collaborates with KIST to enhance biocompatible ultrasonic receivers, enabling efficient power transfer for medical devices.

From National Research Council of Science & Technology 27/05/25 (first released 30/04/25)

A schematic of an ultrasonic receiver that demonstrates how it can be bent and deformed during the process of wirelessly charging the battery of a body-inserted medical device, while maintaining its performance during close attachment to the human body. Credit: Korea Institute of Science and Technology(KIST)

With the increasing demand for underwater and implantable medical electronics, a stable and continuous power supply is essential.

However, conventional wireless charging methods (such as electromagnetic induction and radio frequency-based charging) used in smartphones and wireless earphones suffer from short transmission distances, low energy transfer efficiency in biological tissues, and electromagnetic interference.

To overcome these limitations, researchers are now considering the use of ultrasound as a new wireless power transfer technology.

Ultrasound has the advantage of being human-friendly and less absorbed by tissues, allowing for more reliable energy transfer in implantable and skin-adherent devices.

As a result, wireless charging technology utilizing ultrasonic energy is emerging as the next generation of power transfer.

A research team led by Dr. Sunghoon Hur of the Electronic and Hybrid Materials Research Center at the Korea Institute of Science and Technology (KIST) and Professor Hyun-Cheol Song of Korea University has developed a biocompatible ultrasonic receiver that maintains its performance even when bent.

The receiver overcomes many of the limitations of existing wireless power transmission methods while improving biocompatibility, and is expected to be applied to next-generation wearable and implantable electronic devices.

The researchers also demonstrated wireless charging of batteries by receiving ultrasonic waves, which is an important step toward commercializing the technology.

In particular, the researchers dramatically improved the power conversion efficiency compared to conventional ultrasonic receivers by using high-efficiency piezoelectric materials and a unique structural design.

By designing a stretchable and biocompatible ultrasonic receiver that conforms closely to the curves of the human body while achieving stable power conversion, they were able to transmit 20 mW of power at a distance of 3 cm underwater and 7 mW at a depth of 3 cm from the skin.

This is enough power to continuously power low-power wearable devices or implantable medical devices.

The findings are expected to help accelerate the commercialization of ultrasonic-based wireless charging technology for underwater electronics and implantable medical electronics.

In particular, it is expected to provide a new paradigm for providing safe and continuous power to low-power medical devices such as implantable pacemakers, neurostimulators, and wearable sensors.

It is also expected to be applied not only to medical devices, but also to underwater drones and marine sensors that require long-term power supply.

“Through this research, we have demonstrated that wireless power transmission technology using ultrasound can be applied practically,” said Dr. Sunghoon Hur at KIST.

“We plan to conduct further research for miniaturization and commercialization to accelerate the practical application of the technology.”

(Left) Proposed application of a triboelectric ultrasonic receiver in an implantable medical device.(Right) A comprehensive block diagram of the device Credit: Korea Institute of Science and Technology(KIST)