New technique can insert metals into 'smart' fabrics

Scientists have devised an innovative technique that could be used to incorporate batteries, wireless devices and sensors into fabrics like paper and cotton textiles.

The researchers from Imperial College London in the UK used the technique to print metals such as silver, gold and platinum onto fabrics.

Ultimately these technologies could be used for new classes of low-cost medical diagnostic tools, wirelessly powered sticker-sensors to measure air pollution or clothing with health monitoring capabilities, they said.

Metals have been printed onto fabrics, but until now the process has essentially coated the fabric with plastic which renders the fabric waterproof and brittle.

Described in the journal Advanced Functional Materials, the approach would allow metal inks to cover entire fibres rather than simply coating the surface of the fabric.

"Fabrics are ubiquitous and some forms such as paper, are ancient. With this new method of metallising fabrics it will be possible to create new classes of advanced applications," said Max Grell, a PhD candidate at Imperial College London.

To coat the fibres, the researchers first covered them in microscopic particles of silicon, and then submerged the material into a solution containing metal ions.

This preparatory process, known as SIAM, allows metals to 'grow' throughout the material as the ions are deposited on the silicon particles.

This approach coats metal throughout the fabric, allowing paper and textiles to maintain their ability to absorb water and their flexibility alongside providing a large metallic surface.

These properties are important to the functioning of many advanced technologies, particularly sensors and batteries, where ions in solution must interact with electrons in metals.

The team dropped the silicon ink by hand onto the fabrics, but the process could be scaled up and performed by large conventional printers.

The researchers demonstrated its ability to fabricate the elements required for a number of examples of advanced technologies.

The team also used the method to deposit silver onto paper and then added zinc onto the same paper to form a battery.

The new approach was also used to produce a range of sensors. This included a paper-based sensor to detect the genetic indicators of a disease that is fatal to grass-eating animals and associated with Crohn's disease in humans.

According to the researchers, sensors fabricated within natural fabrics would be cheaper, easy to store and transport, and ultimately could be used in clothing that monitors health.

"We chose applications from a range of different areas to show how versatile and enabling this approach could be," said Grell.

"It involved a lot of collaboration and we hope we have demonstrated the potential of this method so people who specialise in different areas can then develop these applications," he said.