Electron microscopy image of a conductive graphene/cotton fabric. Photo credit: Jiesheng Ren

Electron microscopy image of a conductive graphene/cotton fabric. Photo credit: Jiesheng Ren

UK researchers have developed a new method for depositing graphene-based inks onto cotton to produce a conductive textile, in a development that could lead to commercial opportunities for graphene-based inks in sectors such as high-performance sportswear, military garments and wearable technology.

Working alongside scientists at Jiangnan University in China, the team at the University of Cambridge's Cambridge Graphene Centre (CGC) says the technology opens up new possibilities for flexible and wearable electronics, without the use of expensive and toxic processing steps.

Based on work by the CGC's Dr Felice Torrision on the formulation of printable graphene inks for flexible electronics, the team created inks of chemically modified graphene flakes that are more adhesive to cotton fibres than unmodified graphene.

"Turning cotton fibres into functional electronic components can open to an entirely new set of applications from healthcare and wellbeing to the Internet of Things," says Dr Torrisi "Thanks to nanotechnology, in the future our clothes could incorporate these textile-based electronics and become interactive."

According to the researchers, the adhesion of the modified graphene to the cotton fibre is similar to the way cotton holds coloured dyes, and allows the fabric to remain conductive after several washes. Meanwhile, heat treatment after depositing the ink on the fabric improves the conductivity of the modified graphene.

Graphene is carbon in the form of single-atom-thick membranes, and is highly conductive. The group's work is based on the dispersion of tiny graphene sheets – each less than one nanometre thick – in a water-based dispersion. The individual graphene sheets in suspension are chemically modified to adhere well to the cotton fibres during printing and deposition on the fabric, leading to a thin and uniform conducting network of many graphene sheets. This network of nanometre flakes is the secret to the high sensitivity to strain induced by motion.

A simple graphene-coated smart cotton textile used as a wearable strain sensor has been shown to reliably detect up to 500 motion cycles, even after more than ten washing cycles in normal washing machine, the researchers say.

They add that, while numerous researchers around the world have developed wearable sensors, most of the current wearable technologies rely on rigid electronic components mounted on flexible materials such as plastic films or textiles. These offer limited compatibility with the skin in many circumstances, and are damaged when washed and uncomfortable to wear because they are not breathable.

"Other conductive inks are made from precious metals such as silver, which makes them very expensive to produce and not sustainable, whereas graphene is both cheap, environmentally-friendly, and chemically compatible with cotton," explains Dr Torrisi.

The teams hope the development will lead to commercial opportunities for graphene-based inks in sectors such as high-performance sportswear, military garments and wearable technology.