You’re just about to start your workout. You tap your smartwatch, ready to track your heart rate, steps, distance, calories, and so many other juicy health data metrics. But alas, you forgot to charge your device, and now your staring at a useless black hole strapped to your wrist. You can still work out, but there’s no capturing that fascinating data… because lithium-ion batteries can only hold so much power.
An international research team — comprising members from Penn State University in the United States and China’s Minjiang University and Nanjing University — has developed an alternative power source that could eliminate the need to charge wearable devices. The team created a stretchable, micro-supercapacitor array (MSCA) that harvests bioenergy from the wearer’s respiration and movement.
Existing MSCAs consist of sandwich-like layers of electrodes. That approach has limitations when it comes to smartwatches and other diagnostic and monitoring wearables because these MSCAs don’t stretch well or integrate smoothly with wearable technology.
To address this issue, the research team designed a new type of MSCA based on hybrid electrodes. They used a bridge-like, single plane architecture anchored to graphene foam to achieve durable, reversible stretchability. The device also acts as a triboelectric nanogenerator (TENG), which converts bioenergy to electricity. The team published their findings in the March 2021 issue of the journal Nano Energy.
The conductivity and stability of the new MSCA suggest that it could out-perform batteries in terms of energy density, charging time, and longevity. MSCAs also have eco-friendly value because of their small footprint, a feature that most wearables don’t yet have on their own. Best of all, you might never have to wonder how many calories you burned on your morning run ever again.