RESEARCHERS say their new process paves the way to scalable, green, production of conductive cotton textiles for use in wearable electronics.
The collaborative team from the Cambridge Graphene Centre, UK, and Jiangnan University in China produced a wearable strain sensor by depositing graphene-based ink on cotton. This stands in stark relief to other wearable sensors that rely on rigid electronic components mounted on the likes of plastic films, which are damaged when washed and can be uncomfortable to wear because they are not breathable.
‘Dyeing’ breathable cotton with conductive graphene-based inks is an attractive alternative, but the methods for doing so have until now relied on inefficient processes and toxic chemicals. The team used vacuum filtration to deposit graphene oxide ink onto cotton. Graphene oxide is used over graphene alone because it bonds more easily with cotton. However it is also insulating, the team reports, so efforts have been made to use reduced graphene oxide, which overcomes this issue.
Unfortunately, fabricating conductive cotton fabrics with reduced graphene oxide requires many dipping-dying cycles to deposit enough of the ink, and moreover, reducing the graphene oxide requires toxic reductants such as titanium trichloride and hydrazine.
The team has solved this issue by reducing the deposited graphene oxide inks with a hot press – heating the fabric to 180°C for 60 minutes. The resulting textile was used as a wearable strain sensor and was shown to reliably detect up to 500 motion cycles even after more than 10 washing cycles.
Felice Torrisi, research author from the Cambridge Graphene Centre added: “Turning cotton fibres into functional electronic components can open an entirely new set of applications from healthcare and wellbeing, to the Internet of Things.”
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