Body-motion-powered device could promote bone healing

Zhong Lin Wang has created a device, which gathers power from kinetic energy produced by humans, and converts it to electricity to power wearable devices or implants

Zhong Lin Wang, a materials scientist at Georgia Tech in Atlanta and the Chinese Academy of Sciences in Beijing, has already shown his group's energy-scavenging device can power a pacemaker.

Now he and his Beijing team have shown that they can also power a laser for accelerating bone-healing.

Wang's power converting devices rely on static electricity. They sandwich two flexible films with oppositely charged surfaces, one of polydimethylsiloxane and the other of indium tin oxide, together in an electrical circuit.

With the bend of an elbow or the rise and fall of the chest, the films are squashed, changing the voltage between them and driving a current in the circuit that can power lasers, LEDs, or other devices.

Biologists have shown that low-intensity light from infrared lasers can encourage the growth of early-stage bone cells, a key part of bone healing.

Wang and his team wanted to make a simple, self-powered device to carry out this kind of light therapy.

In vitro tests showed that an implantable, generator-powered, infrared laser accelerated the proliferation of early-stage mouse bone cells by 15% after two days.

They also showed that, when implanted in mice in between the diaphragm and the liver, the generator produced power from the diaphragm's motion.

The device converts about 50% of mechanical energy into electrical energy which, Wang says, is good enough for proof-of-concept medical devices, but practical systems will require higher conversion rates.

Next Wang’s team plan to work on boosting the generator's power output.

Wang said: "We want to continue improving the power output so that we can speed up wound healing."