DEVICE GENERATING ELECTRICITY

 WEARABLE DEVICE USES SMALL MAGNETS TO GENERATE ELECTRICITY

UCLA's self powered,stretchable,waterproof,soft magnetoelastic generator Jun Chen UCLA

While we've heard a lot about wearable piezoelectric devices that generate electricity from the movement of people, they don't work well under certain conditions. However, a new transport of bioelectric energy could attract attention where it failed

While piezoelectric devices generate an electric current when pressed or pushed, this new tool is a little different. It uses the so-called magnetoelastic effect, in which the magnets in a material are compressed and separated by mechanical stress, creating an electric current with a change in the strength of that material's magnetic field.

In the past, magnetoelastic generators were made of hard metal alloys that were too hard to fit comfortably on the body. However, under the direction of Assistant Professor Jun Chen, the team at UCLA has developed a model that is soft and flexible enough to be worn on parts of the body that move frequently. It consists of a platinum catalyst silicon polymer matrix with nanoscale neodymium-iron-boron magnets inside.

Tied to the volunteer's elbow with silicone tape, the device generated an electric current of 4.27 milliamperes per square centimeter. This happened when the man's elbow moved, causing the tiny magnet to be repeatedly released and compressed. Experiments have also shown that the device is so sensitive that it can even convert a human pulse wave into an electrical signal - that is, it can be integrated into a self-driving heart rate monitor.

According to Chen, generators have several key advantages over existing alternatives.

"Current technologies for converting biomechanics into electrical energy, including triboelectric and piezoelectric nanogenerators, face unavoidable challenges such as very low current densities and high internal impedances," he said. "More importantly, their electrical performance is susceptible to environmental humidity caused by sweat and the human body's fluid environment, which severely limits their practical application on the body."

In contrast, soft magnetoelastic generators have a higher output and are not affected by moisture. Chen added that while other types of generators can be protected from moisture with a waterproof coating, adding such a coating usually reduces their efficiency in converting biomechanics into electrical energy.

The research is described in a paper that was recently published in the journal Nature Materials.

Source: UCLA via EurekAlert