'Washable, wearable devices could be woven into clothes'

Cambridge scientists have developed wearable electronic components that can be incorporated directly into fabrics.

The devices could be used for flexible circuits, healthcare monitoring, energy conversion, and other applications, according to the study published in the journal Nanoscale.

Researchers have shown how graphene -- a two-dimensional form of carbon -- and other related materials can be directly incorporated into fabrics to produce charge storage elements such as capacitors.

This paves the way for textile-based power supplies which are washable, flexible and comfortable to wear.

The research demonstrates that graphene inks can be used in textiles able to store electrical charge and release it when required.

The new textile electronic devices are based on low-cost, sustainable and scalable dyeing of polyester fabric.

The inks are produced by standard solution processing techniques.

Building on previous work by the same team, the researchers at the University of Cambridge in the UK designed inks which can be directly coated onto a polyester fabric in a simple dyeing process.

The versatility of the process allows various types of electronic components to be incorporated into the fabric.

Most other wearable electronics rely on rigid electronic components mounted on plastic or textiles.

These offer limited compatibility with the skin in many circumstances, are damaged when washed and are uncomfortable to wear because they are not breathable.

"Other techniques to incorporate electronic components directly into textiles are expensive to produce and usually require toxic solvents, which makes them unsuitable to be worn," said Felice Torrisi from Cambridge.

"Our inks are cheap, safe and environmentally-friendly, and can be combined to create electronic circuits by simply overlaying different fabrics made of two-dimensional materials on the fabric," Torrisi said.

The researchers suspended individual graphene sheets in a low boiling point solvent, which is easily removed after deposition on the fabric, resulting in a thin and uniform conducting network made up of multiple graphene sheets.

The subsequent overlay of several graphene and hexagonal boron nitride (h-BN) fabrics creates an active region, which enables charge storage.

This sort of 'battery' on fabric is bendable and can withstand washing cycles in a normal washing machine.

"Textile dyeing has been around for centuries using simple pigments, but our result demonstrates for the first time that inks based on graphene and related materials can be used to produce textiles that could store and release energy," said Professor Chaoxia Wang from Jiangnan University in China.

"Our process is scalable and there are no fundamental obstacles to the technological development of wearable electronic devices both in terms of their complexity and performance," Wang said.

The work opens a number of commercial opportunities for ink based on two-dimensional materials, ranging from personal health and well-being technology, to wearable energy and data storage, military garments, wearable computing and fashion.

"Turning textiles into functional energy storage elements can open up an entirely new set of applications, from body-energy harvesting and storage to the Internet of Things," said Torrisi.

"In the future our clothes could incorporate these textile-based charge storage elements and power wearable textile devices," Torrisi said.