Ultrasound Powers Medical Implants Wirelessly

Advancements in Wireless Power for Medical Implants and Underwater Electronics

Medical implants and underwater electronics have long faced a significant challenge: how to power them safely and continuously. Traditional wireless charging methods, such as electromagnetic induction or radio frequency waves, work well for everyday devices like earbuds or phones. However, when these technologies are used inside the human body or underwater, they encounter serious limitations. Energy transfer becomes less efficient through biological tissues, and electromagnetic waves can cause interference or even harm sensitive organs.

To address this issue, researchers have turned to ultrasound technology. Unlike radio waves, ultrasound waves can pass more easily through biological tissue without being absorbed or causing damage. They also do not rely on electromagnetic fields, making them a safer option for use within the human body. This innovation is now being applied to power wearable devices and implanted medical electronics, offering new possibilities for healthcare and marine technology.

A Breakthrough in Ultrasound-Powered Devices

A recent study from the Korea Institute of Science and Technology (KIST), in collaboration with Korea University, has introduced a flexible and biocompatible ultrasonic receiver. Published in the journal Advanced Materials, this device can bend and stretch with the body while still converting sound waves into usable electrical power. The technology is expected to power medical devices such as pacemakers and neurostimulators, as well as underwater sensors and marine drones.

Dr. Sunghoon Hur of KIST explained, “Through this research, we have demonstrated that wireless power transmission technology using ultrasound can be applied practically. We plan to conduct further research for miniaturization and commercialization to accelerate the practical application of the technology.”

How the New Receiver Works

The key to this innovation lies in a tiny, thin material called a triboelectric nanogenerator, or TENG. When paired with ultrasound waves, it converts mechanical energy into electricity. This process occurs within a stretchable and flexible layer made of advanced polymers.

The team developed a structure called a dielectric-ferroelectric boosted ultrasonic TENG (US-TENGDF-B). This design solves common issues that previous triboelectric generators faced, such as stiffness or low energy output. The new system remains effective even when bent or twisted, which is essential for medical devices that must fit into curved parts of the human body.

Using this technology, the researchers successfully transmitted 20 milliwatts of power across 3 centimeters underwater and 7 milliwatts at a depth of 3 centimeters inside the human body. These amounts are sufficient to power many types of medical implants, including pacemakers and sensors.

Design and Performance

The new material’s strength comes from its layered design. One critical component is a mix of polyvinylidene fluoride-trifluoroethylene (P(VDF-TrFE)) and tiny particles of calcium copper titanate (CCTO). Together, these materials increase charge capacity and improve energy capture from ultrasound.

The device is sealed in a clear, flexible coating made from PDMS, a silicon-based substance commonly used in medical tools. This outer layer makes the device waterproof and safe for the body.

Flexibility and Adaptability

Medical implants must adapt to movement and shifting body positions. To test this, the researchers bent the ultrasonic receiver into different shapes—concave (curved inward) and convex (curved outward)—and measured energy output. In the concave position, energy production increased because the shape trapped more ultrasound waves, causing them to collide more frequently with the surface. In the convex position, there was a slight drop in output due to tension in the PFA film, but the device still performed well overall.

The device is just 0.4 millimeters thick, allowing it to fit snugly against tissues and organs for long-term use in implantable systems.

The Science Behind the Boost

At the heart of this innovation is an improved triboelectric effect, where two materials generate electricity by rubbing or separating. The researchers added an extra layer of science to boost performance: ferroelectric materials. These have tiny dipoles that can be aligned using an electric field. When the dipoles in the ferroelectric layer match the electric field of the triboelectric layer, energy generation improves, especially when the dipoles are aligned downward. This alignment increases the internal electric field and enhances charge separation.

Tests showed that the downward-polarized setup could generate up to 6.7 milliwatts of power and around 26 volts from a distance of 35 millimeters—enough for short-term charging of implantable batteries deep in the body.

Future Applications and Benefits

The development of the US-TENGDF-B could change how medical implants are powered. Instead of requiring repeated surgeries for battery replacement, this technology allows for remote charging through skin and muscle. This would reduce the risk of infection, lower patient stress, and decrease healthcare costs.

The technology is particularly promising for pacemakers, neurostimulators, glucose sensors, and future artificial hearts. It could also be used to power underwater robots, long-term marine sensors, and other equipment in extreme environments.

The team from KIST and Korea University hopes to further shrink the size of the receiver and boost its energy output, enabling deeper placement in the body or longer periods between charges.

Wireless ultrasound charging may soon become a reality, offering a safer, easier, and more reliable way to power implants and wearable electronics.