Triboelectric Generators Paired with Unique Stretchable Micro-Supercapacitors Could Power Wearables

As portable and wearable electronics devices become more and more common and increasingly important parts of our lives, it is more apparent than ever before that our energy storage technology is lacking. Even your smartphone, with its relatively large battery, struggles to make it through the day without needing a charge. The problem is even more pronounced with small wearable devices like sensor patches. Supercapacitors have a higher energy density than conventional batteries, but are bulky and rigid. That’s why researchers from Pennsylvania State University have developed flexible, stretchable micro-supercapacitors that could provide limitless power when combined with triboelectric generators.

Triboelectric generators and nanogenerators are energy-harvesting devices that are able to convert minuscule movement and vibration into usable electricity. At a small scale, these triboelectric generators could use your own natural body movement to produce enough energy to power wearable sensors. But you aren’t always moving, which means energy needs to be stored for the moments when you are still. Micro-supercapacitors are ideal for this situation, because they have a high power density, can charge and discharge quickly, and can be made very small. Unfortunately, today’s micro-supercapacitors are fabricated in rigid, three-dimensional packages that limit how much a wearable sensor patch could flex and stretch. These new micro-supercapacitors are fabricated in a novel way that makes them suitable for electronic skin patches.

Conventional micro-supercapacitors have a structure that is similar to battery, with stacked cell geometry. These new micro-supercapacitors are constructed in a completely different way, with a series of cell “islands” arranged in a serpentine pattern and interconnected by trace “bridges.” Those islands and bridges are printed onto very thin zinc-phosphorus nanosheets using 3D laser-induced graphene foam. Each island is rigid, but the winding bridges between them can be stretched and flexed without damaging the circuit. The result is a micro-supercapacitor that could be easily integrated into electronic patches that can be comfortably worn on the skin for long periods of time. The micro-supercapacitor would be charged by a triboelectric nanogenerator as you move, ensuring that the sensors embedded in the patch receive continuous power without requiring that users manually recharge batteries. This power generation and storage system would only be suitable for very low-power sensors, but that would still be incredibly useful for applications like health monitoring.