Stretchy, breathable circuits can be printed directly onto fabric
Image credit: Felice Torrisi
An international research team has printed integrated circuits straight onto fabric using standard inkjet printing techniques, raising the possibility for more comfortable smart clothing and other wearable technologies.
Consumers can already buy a huge range of wearable devices, although these are typically made from rigid components mounted on or incorporated into rubber, fabric and other materials. These devices tend to limit movement and are not breathable, proving uncomfortable to wear for extended periods.
The development of stretchable, breathable electronic components and whole circuits that can be printed directly onto polyester is a step forward from existing impractical wearable electronics.
A team led by researchers at the University of Cambridge has demonstrated that it is possible to print graphene directly onto fabric. Graphene – an atom-thick layer of carbon – has a range of extremely useful properties, including high electrical conductivity.
The researchers developed cheap, environmentally friendly inks based on graphene and other two-dimensional materials. These inks have low boiling points, and can be directly printed onto polyester fabric using a standard inkjet printing technique to create transistors.
The researchers found that by adapting the roughness of the synthetic fabric, they were able to optimise the performance of the components so that they were able to print not just single components but fully integrated circuits with a variety of components.
The use of conventional printing equipment and methods, such as inkjet or screen printing, in order to create electronic devices and circuits is likely to allow for more low-cost and flexible electronic devices to be developed, such as flexible display screens and smart clothing.
“Other inks for printed electronics normally require toxic solvents [that] are not suitable to be worn, whereas our inks are […] cheap, safe and environmentally friendly,” said Dr Felice Torrisi, senior author of the Nature Communications paper describing the work, and a researcher at the Cambridge Graphene Centre.
“[They] can be combined to create electronic circuits by simply printing different two-dimensional materials on the fabric.”
These simple integrated circuits were capable of surviving up to 20 washes in a standard washing machine.
“Digital textile printing has been around for decades to print simple colourants on textiles, but our result demonstrates for the first time that such technology can also be used to print the entire electronic integrated circuits on textiles,” said Professor Roman Sordan, a researcher at Politecnico di Milano, who collaborated with the Cambridge team on the project.
“Although we demonstrated very simple integrated circuits, 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.”
According to the team, the possibilities for applications of this technique include stretchy, breathable devices for personal health monitoring, energy harvesting, military apparel and smart fashion.
“Turning textile fibres into functional electronic components can open up an entirely new set of applications from healthcare and well-being to the Internet of Things,” said Dr Torrisi. “Thanks to nanotechnology, in the future our clothes could incorporate these textile-based electronics, such as displays or sensors, and become interactive.”