The increasing miniaturization of pacemakers and other medical implants poses an energy challenge: device designers are tasked with developing charging systems without the need for clunky external power sources or repeated invasive surgeries for battery replacement. An energy harvesting solution that converts ultrasound power into electric energy to wirelessly power implants through the skin is being developed by researchers in Saudi Arabia.

Engineers from King Abdullah University of Science and Technology (KAUST) and King Saud bin Abdulaziz University for Health Sciences formulated a flexible, electricity-conducting hydrogel that absorbs sound waves passed through the body. The hydrogel is synthesized with water, polyvinyl alcohol and nanoflakes of MXene, a 2D film of transition metal carbides, nitrides or carbonitrides. Applied pressure exerted by ultrasound energy forces the flow of electrical ions in water, filling the hydrogel and generating an electrical current.

The encapsulated hydrogel generator successfully charged an electrical device buried in a centimeter-thick piece of beef by harvesting energy from ultrasound tips and ultrasound imaging probes.

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