Without the inconvenience of batteries, wearable technology such as fitness trackers and patient monitors could harvest biometric data virtually non-stop. A self-powered solution would also remove a big barrier that has slowed the progress of bringing smart garments to market; it’s hard to convince consumers they need battery-powered clothes that weigh more and have to be plugged at night. An innovative new device developed at the UCLA Samueli School of Engineering could soon power wearables via a flexible magnetic field that converts body motions into energy.

We’ve covered other creative designs that obtain energy from the human body, including a piezoelectric device powered by fingertip sweat and a wearable microgrid that can store the energy it harvests for future use. The novel approach by the UCLA bioengineers is particularly noteworthy because flexible magnetic technology has some practical benefits compared to other self-powering methods. 

The UCLA team based their device on the magnetoelastic effect: a phenomenon in which the magnetic properties of rigid metal alloys change when subjected to mechanical stress. Rather than hard alloys, however, the team designed a silicone polymer matrix containing a network of microscopic magnets. 

When attached to a soft, silicone band and worn on the elbow, the paper-thin matrix becomes a magnetoelastic generator. Bending the elbow causes mechanical stress that triggers minuscule magnetoelastic changes; these continuous magnetic shifts generate electricity.

In testing, the researchers observed that elbow movements caused the flexible device to generate a magnetoelastic effect that was four times greater than tiny systems made of rigid alloys. They also point out that the device can even convert the subtle movements of the pulse at the wrist into electricity. The bioengineers published their research in the journal Nature Materials.

One advantage the UCLA device has over previous endeavors is that it doesn’t require sweat or any active movements. As long as you have a pulse, you’ve got continuous power. Additionally, sweat and other variables such as humidity won’t interfere with its ability to produce energy. The device is still in the earliest stages of development, but its impact on wearables and smart garments looks promising due to the practical nature of magnetic technology.