Implantable device gives electrical stimulation without battery

The ultrasound-powered technology may have potential as Parkinson's therapy

Marisa Wexler, MS avatar

by Marisa Wexler, MS |

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A human brain is shown with electric currents running across its base.

Scientists have created an implantable device that can provide electrical stimulation in the body without need for a battery.

The new technology, which is powered by ultrasound, may serve as a useful platform to develop next-generation implantable devices to treat conditions such as Parkinson’s disease.

The team described its breakthrough in the study “High-Performing and Capacitive-Matched Triboelectric Implants Driven by Ultrasound,” which was published in Advanced Materials.

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“We have addressed the challenges in the field of implantable medical devices using ultrasound-based energy transmission technology that is harmless to the human body,” Sung-Min Park, PhD, a professor at Pohang University of Science and Technology in Korea, said in a press release.

Park added that the team expects this new tech “will promote the emergence of a next-generation medical industry, including the treatment of intractable diseases using implantable devices.”

Over the past few decades, there have been major breakthroughs in the development of electrical devices that can be implanted into the body to help manage health conditions. In Parkinson’s, a procedure called deep brain stimulation (DBS) — where an electrode is implanted to provide electrical stimulation to specific regions of the brain — can be used to help ease disease symptoms.

Charging the implantable device has been an obstacle

Electrodes for DBS and similar devices require a power source to function, which traditionally has consisted of a battery implanted alongside the device. This has notable drawbacks because the battery eventually will run out of power and need to be replaced, which is expensive and burdensome for patients, and poses a high risk of surgical complications.

In theory, wireless charging technologies could be used to charge implanted batteries. But these devices usually are encased in titanium, which helps ensure the device stays stable and doesn’t cause problems with body tissue. But is also stops radio waves, the power source for wireless charging, from getting to the device.

Here, researchers devised a device that can be charged using ultrasound, a type of high-frequency sound wave that’s already used for many medical applications including imaging of the inside of the body. Ultrasound has the advantage of already being proven safe for people.

The device consists of several layers of specialized materials. When ultrasound is applied, these layers vibrate and rub against each other, which generates static electricity. The device then can capture this electricity and use it for power.

The researchers noted that the device’s “energy transmission efficiency is the highest among those reported so far.”

Tests using human cells in dishes showed that the device didn’t cause noteworthy toxic effects. When implanted into rats, the device caused some local inflammation, but no more than reactions seen with devices that are currently used for procedures like DBS.

As a proof-of-concept, the researchers used the device to stimulate a nerve in the ankle of rats, which is an established method for treating overactive bladder. Results showed that, as designed, the ultrasound-charged device was able to reduce bladder function.

‘A promising solution”

“The technical advances reported herein strongly suggest that the proposed battery-free device system … is a promising solution toward the permanent implantation of bioelectric devices to treat various chronic dysfunctions,” the scientists concluded.

“Devices manufactured based on highly biocompatible materials exhibit excellent mechanical and chemical stability, making them suitable for treating various diseases requiring long-term therapy,” said Sang-Woo Kim, PhD, a professor at Pohang and study co-author. “Non-battery, miniaturized components with established long-term stability are expected to bring forth new innovations in the market of human-insertable medical devices,” Kim said.