Amay Bandodkar

Wearable technology can provide real-time information about a person’s health and fitness, but creating sensors that can collect data without a cumbersome and impractical system of staying powered has proved difficult. Amay Bandodkar thinks he’s hit on a new way of creating “self-powered” biochemical sensors through unconventional technologies, making wearable tech lighter and less cumbersome. It’s about four times smaller and 20 times lighter than similar devices produced two years ago, he says.

The key to shrinking the sensor was overhauling how it’s powered. “All the groups that were working on this were using these really bulky batteries, and the sensor was around 3% of the total size and weight,” he says. So he built a sensor that doesn’t require a battery: it harnesses the catalytic properties of enzymes to generate signals without the need for power sources. While this concept can be used to develop self-powered sensors for some chemicals, for other kinds of sensors that still need a power source, Bandodkar has developed a lightweight battery that runs on sweat. It’s made of a magnesium anode and a cathode made of silver and silver chloride, separated by a dry cellulose membrane. When a person wearing it starts to perspire, the cellulose membrane absorbs the sweat and acts as an electrolyte, effectively turning the battery on and powering the sensor.

Bandodkar has successfully tested out a heart-rate sensor running on his battery, opening the gateway for heart-monitoring wearables.