Providing power to medical implants has been a challenge, as batteries require routine replacements via Schematic of ultrasound passing through skin to the triboelectric device. Source: Sungkyunkwan Universityinvasive surgery, and external power packs are associated with a high risk of infection where wires enter the body. An alternative devised by researchers from Sungkyunkwan University in South Korea focuses on a triboelectric generator that converts externally applied ultrasound into an internal electricity source capable of delivering sufficient energy to recharge a battery.

An ultrasound probe delivers mechanical energy through skin and liquids, enabling its harvest by a thin implantable vibrating triboelectric generator. As it absorbs the ultrasound waves, the generator yields an electric current that is substantial enough to power cardiac implants and other medical devices.

The technology was demonstrated by recharging a lithium-ion battery suspended in water at 166 microcoulombs per second. The generator produced 2.4 V and 156 microamps when placed within pig tissue and resonated using an external ultrasound transducer.