Implantable biomedical devices—like pacemakers, insulin pumps and neurostimulators—are becoming smaller, but hurdles remain for powering them. A new wireless charging device developed by Penn State scientists could improve powering capability for implants while still being safe for our bodies, according to the researchers.

The new device can harvest energy from magnetic fields and ultrasound sources simultaneously, converting this energy to electricity to power implants within safety limits for human tissue, the scientists reported in the journal Energy & Environmental Science.

Higher power miniaturized device

“Our device may unlock next-generation biomedical applications because it can generate 300% higher power than the current state-of-the-art devices,” said Bed Poudel, research professor in the Department of Materials Science and Engineering at Penn State and co-author of the study. “By combining two energy sources in a single generator, power generated from a given volume of the device can be significantly improved, which can unlock many applications that were not possible before.”

Using this technology, battery-free bioelectronic devices could be miniaturized to millimeter-sized dimensions, making them easily implantable and allowing distributed networks of sensors and actuators to measure and manipulate physiological activity throughout the body. This would enable precise and adaptive bioelectronic therapies with minimal risks or interference with daily activities, according to the scientists.

Problems with current implants

Traditional implants like pacemakers are typically powered by batteries and charged using cables, with limited battery lifespan and required surgery to replace them—posing a risk of infection or other medical complications.

Charging or directly powering implants wirelessly could extend their lifespan, but conventional wireless charging technology (used for cell phones and electric vehicles, for example) may not be safe as implants continue to shrink. This requires increased power, which could be harmful to the body, say the researchers.

Converting a magnetic field and piezoelectric layer into a safe electric current

The new devices use a two-layer process for converting energy to electricity. One layer is magnetostrictive, which converts a magnetic field into stress. And the other is piezoelectric, which converts ultrasound energy (vibrations) into an electric field. The combination allows the device to generate an electric current without damaging tissue.

The technology also has implications for powering things like wireless sensor networks in smart buildings to monitor energy and operational patterns, and to use that information for remotely adjusting control systems, the scientists noted.

The National Science Foundation supported this work. Some of the researchers on this study received support from the DARPA MATRIX program and the Army RIF program.

Citation: Schneider, S., Lee, J.H. & Mathis, M.W. Learnable latent embeddings for joint behavioural and neural analysis. Nature 617, 360–368 (2023). https://doi.org/10.1038/s41586-023-06031-6 (open-access)

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