Triboelectric Generator Built From Low-Cost Flexible PCBs Can Power Bodily Sensors Without Batteries
Built from low-cost flexible PCBs, the nanogenerator is capable of powering a body-worn sweat sensor — even if the user is sedentary.
Researchers at Caltech and Peking University have unveiled a triboelectric sensor that can power wearables through simple bodily motion — proving the concept with an an energy-harvesting sweat sensor built from low-cost, commonly-available materials.
Wearable sensors which can track everything from health to athletic performance are great in concept, but hampered by the need for battery power — either because the batteries make them bulky or because you need to remember to charge the devices between uses. A team led by Assistant Professor Wei Gao has an alternative approach: A triboelectric generator, powering a sensor by harvesting energy from movement.
"Our triboelectric generator, also called a nanogenerator, has a stator, which is fixed to the torso, and a slider, which is attached to the inside of the arm," Gao explains. "The slider slides against the stator during human motion, and, an electrical current is generated at the same time. The mechanism is quite simple. Friction results in electrical generation. This is not something new, concept-wise."
What is new is how the nanogenerator was built: "Instead of using fancy materials, we use commercially available flexible circuit boards," Gao notes. "This material is cheap and very durable and mechanically robust over long periods of time."
The resulting generator can't produce much power — the team estimates it would take one with 100 square metres of surface area to power a single 40-watt lightbulb — but it's enough to feed a capacitor which, when charged, can drive a sweat sensor and transmit readings to a nearby smartphone or tablet via Bluetooth.
The team's work has been published under open-access terms in the journal Science Advances.