An innovative method for printing metals such as silver, gold and platinum onto natural fabrics could lead to new classes of low-cost medical diagnostic tools, wirelessly powered sticker-sensors for measuring air pollution or clothing with health monitoring capabilities.
Until now, efforts to print metal onto fabrics have typically involved first coating the fabric with plastic, rendering it waterproof and brittle. But the new technique, developed by a cross-disciplinary team at Imperial College, allows metal inks to cover entire fibres rather than simply coating the surface of the fabric.
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 (Si ink-enabled autocatalytic metallization), 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 group used the technique to create silver coil antennas on paper, which can be used for data and power transmission in wireless devices such as Oyster cards and contactless payment systems. It also used the method to deposit silver onto paper and then added zinc onto the same paper to form a battery.
The method was also used to produce a range of sensors including a paper-based sensor to detect the genetic indicators of a disease that is fatal to grass-eating animals (Johne’s disease).
Whilst the researchers dropped the silicon ink by hand onto the fabrics they claim that the process could be scaled up and performed by large conventional printers.
The group claims that sensors fabricated within natural fabrics would be cheaper, easy to store and transport, and ultimately could be used in clothing that monitors health.
Commenting on the technique, first author of a paper on the work PhD candidate Max Grell said: “The beauty of this approach is that it can…combine different technologies to serve a more complex application, for example low-cost sensors can be printed on paper that can then transmit the data they collect through contactless technology. This could be particularly useful in the developing world where diagnostic tests need to be conducted at the point of care, in remote locations and cheaply.”
The team has applied for a patent and is now looking for industry partners to help commercialise the technology.