A research team led by 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 flexible, biocompatible ultrasonic receiver that enables wireless charging underwater. The new technology has potential applications in implantable medical devices and underwater electronics.
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, the researchers turned to ultrasound, which has the advantage of being human-friendly and less absorbed by tissues, allowing for more reliable energy transfer in implantable and skin-adherent devices.
The new device offers a dramatically improved power conversion efficiency compared to conventional ultrasonic receivers thanks to the use of 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, the researchers were able to transmit 20 mW of power at a distance of three centimetres underwater and 7 mW at a depth of three centimetres 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 commercialisation of ultrasonic-based wireless charging technology for underwater electronics and implantable medical electronics. According to the researchers, their work 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 could also be applied to underwater drones and marine sensors that require long-term power supply.
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‘Through this research, we have demonstrated that wireless power transmission technology using ultrasound can be applied practically,’ said Hur. ‘We plan to conduct further research for miniaturisation and commercialisation to accelerate the practical application of the technology.’
The research has been published in Advanced Materials.