UCLA Bioengineers Create New Class of Giant Magnetoelastic Effect That Converts Human Motions To Electricity

A team of bioengineers at the University of California, Los Angeles (UCLA) has in a technological breakthrough invented a novel soft and flexible self-powered bioelectronic device that converts human body motions into electricity that can be used to power wearable and implantable diagnostic sensors. The new technology uses human actions like bending an elbow, a pulse on one’s wrist and some other subtle actions to generate electricity.

In a paper that has UCLA Samueli postdoctoral scholar Yihao Zhou and graduate student Xun Zhao as co-first authors of the study, it was discovered the change of how much a material is magnetized when tiny magnets are constantly pushed together and pulled apart by mechanical pressure, known as the ‘magnetoelastic effect’ can be found in a soft and flexible system, aside from the known rigid systems.

The team while trying to prove this concept made use of microscopic magnets dispersed in a paper-thin silicon matrix to bring about a magnetic field that has changes in strength when the matrix is undulated. In this process, with the shift in magnetic field strength, electricity is generated.

Popular journal, Nature Materials on September 30published a research study highlighting the discovery, detailing the theoretical model behind the breakthrough, and its demonstration, in a research study also highlighted by Nature.

“Our finding opens up a new avenue for practical energy, sensing and therapeutic technologies that are human-body-centric and can be connected to the Internet of Things,” said study leader Jun Chen, an assistant professor of bioengineering at UCLA Samueli. “What makes this technology unique is that it allows people to stretch and move with comfort when the device is pressed against human skin, and because it relies on magnetism rather than electricity, humidity and our own sweat do not compromise its effectiveness.”

Chen together with his team created a small, flexible magnetoelastic generator that consisted of a platinum-catalyzed silicone polymer matrix and neodymium-iron-boron nanomagnets, then affixed it to a subject’s elbow with a soft, stretchy silicone band. The resultant magnetoelastic effect seen was four times more than rigid metal alloys of similar setups. The device generated electrical currents of 4.27 milliamperes per square centimeter, 10,000times better than the next best comparable technology.

The sensitivity of the flexible magnetoelasticgenerator is so inherent that it can convert human pulse waves into electrical signals while acting as a self-powered, waterproof heart-rate monitor. Wearable devices such as a sweat sensor or a thermometer can be powered by the subsequent electricity generated.

There have been consistent moves to use wearable generators that harvest energy from human body movements to power sensors and other devices but the progress was inhibited by lack of practicality. An instance in this case is a rigid metal alloys with magnetoelastic effect, it is unable to sufficiently bend against the skin to be able to produce sizeable power for viable applications.

Devices that based its reliance on static electricity may have issues generating enough energy, with their performances suffering in humid  conditions or when the human skin has a sweat, this prompted some scientists to encapsulate the devices to keep out water, but that has been seen to reduce their effectiveness.

The wearable generators the team at UCLA worked on was able to test well after it was soaked in artificial perspiration for a week, a gratifying espouse we must say.

Reference: “Giant magnetoelastic effect in soft systems for bioelectronics” 30 September 2021, Nature Materials.
DOI: 10.1038/s41563-021-01093-1