Researchers have created highly stretchable supercapacitors for powering wearable electronics that consist of crumpled carbon nanotube (CNT) forests. The supercapacitors demonstrated solid performance and stability, even when stretched to 800% of their original size for thousands of stretching/relaxing cycles.

An improved power source for wearables is provided via crumpled carbon nanotube (CNT) forests. (Image: MSU)

Instead of having a flat, thin film strictly constrained during fabrication, the design enables a three-dimensionally interconnected CNT forest to maintain good electrical conductivity, making it much more efficient, reliable, and robust.

In the medical field, stretchable/wearable electronics are being developed that are capable of extreme contortions and can conform to complicated, uneven surfaces. In the future, these innovations could be integrated into biological tissues and organs to detect disease, monitor improvement, and even communicate with medical practitioners. Another application could be patches of smart skin for burn victims that can monitor healing while powering themselves.

The crumpled standing CNTs grow like trees with their canopies tangled on wafers. This forest, however, is merely 10 to 30 micrometers high. After transferred and crumpled, the CNT forest forms stretchable patterns like a blanket. The 3D-interconnected CNT forest has a larger surface area and can be easily modified with nanoparticles or adapted to other designs.

Even when stretched up to 300% along each direction, they still conduct efficiently. Other designs lose efficiency, can usually be stretched in only one direction, or malfunction completely when they are stretched at much lower levels.

Metal oxide nanoparticles can be easily impregnated into the crumpled CNTs so that the invention’s efficiency improves much more. The approach can spark the advancement of self-powered, stretchable electronic systems.

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