Dual-energy harvesting device could power future wireless medical implants

Implantable biomedical devices, such as pacemakers, insulin pumps and neurostimulators, are becoming smaller and use wireless technology, but obstacles remain to powering next-generation implants. A new wireless charging device developed by Penn State scientists could significantly improve the power capability of implants while remaining safe for our bodies, researchers said.

The new device can simultaneously harvest energy from the magnetic field and ultrasound sources, converting that energy into electricity to power the implants, the scientists reported in the journal. Energy and environmental sciences. This is the first device capable of harvesting these dual-energy sources simultaneously with high efficiency and operating within the safety limits of human tissue, the team said.

“Our device could unlock next-generation biomedical applications because it can generate 300 percent more power than current state-of-the-art devices,” said Bed Poudel, research professor in Penn’s Department of Materials Science and Engineering. State et co. -author of the study.

“By combining two energy sources into a single generator, the 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 dimensions, making them easily implantable and enabling distributed networks of sensors and actuators to measure and manipulate physiological activity throughout the body. According to scientists, this would enable precise and adaptive bioelectronic therapies with minimal risk or interference with daily activities.

More traditional implants like pacemakers are typically powered by batteries and charged using cables. But batteries have a limited lifespan and surgery may be required to replace them, posing a risk of infection or other medical complications.

Directly charging or powering the implants wirelessly could extend their lifespan, the scientists said. But conventional wireless charging technology used for cell phones and electric vehicles may not be ideal as implants continue to shrink.

“The problem is that as you make these implants less invasive by making them smaller and smaller, the efficiency of wireless charging becomes much lower,” said Mehdi Kiani, associate professor of electrical engineering at Penn State and co-author of the study. “To solve this problem, the power needs to be increased. But the problem is that high-frequency electromagnetic waves could be harmful to the body.”

According to the researchers, magnetic field and ultrasound energy operating at lower frequencies are attractive options for powering or wirelessly charging implants. Previous work by other scientists has focused on creating devices that can harvest one of these energy sources, but not at the same time, the scientists said. However, this single-source approach may not provide enough power to charge future, smaller medical implants.

“We can now combine two modalities in a single receptor,” said Sumanta Kumar Karan, a postdoctoral researcher in Penn State’s Department of Materials Science and Engineering and lead author of the paper. “It can exceed any individual modality because we now have two energy sources. We can increase the power by four times, which is really significant.”

The devices use a two-step process to convert magnetic field energy into electricity. One layer is magnetostrictive, which converts a magnetic field into stress, and the other is piezoelectric, which converts stress or vibrations into an electric field. The combination allows the device to transform a magnetic field into an electric current.

And the piezoelectric layer can also simultaneously convert ultrasound energy into electric current, the researchers said.

“We have combined these energy sources in the same footprint, and we can generate enough energy that can be used to do the things that the next generation implants will be called upon to do,” Poudel said. “And we can do it without damaging the tissue.”

The technology also has implications for powering things like wireless sensor networks in smart buildings. These networks notably monitor energy and operational patterns and use this information to adjust remote control systems, the scientists said.