A Japanese research Group, led by Takao Someya, professor at the School of Engineering, the University of Tokyo, has developed a new type of conductive ink which can be used to print fine circuits on clothes. Using the ink, everyday clothes can be screen printed to have computing capabilities, and can be made to perform a variety of computational jobs. The lead image in this feature demonstrates a touch sensor using a circuit printed on a cloth.
The ink retains its conductivity almost in a lossless manner even when the fabric it’s printed on is stretched up to 3.15 times. In earlier experiments to facilitate wearable computing, conductive thread and cloth have been proposed. However, with the thread materials being interwoven, and because of a variety of other limitations, these conductive threads are difficult to be given the shape of a digital circuit.
The printed circuit on cloth, along with the printable conductive ink
The conductive ink, on the other hand, makes it really simple to print a circuit on the cloth. Existing screen printing technologies can be used to create functional circuits. Really fine circuit patterns with a line width as small as about 100μm can be printed in one go. With its high conductivity even with the cloth in a highly stretched state, the technology can effectively turn clothes into a printed-circuit board.
The screen used to print the circuit on cloth, along with the output
In the research group’s experiments, the conductivity of the ink when the cloth was stretched by 3.15 times was still 182S/cm. This is substantially higher than the conductivity of the previous materials developed by Someya in 2009, which went as low as 6S/cm when the material was stretched by 2.34 times.
Lighting an LED bulb using printed circuit on cloth
The ink used for these conductive circuit boards on clothes is comprised of a fluorine-based surfactant in addition to silver flakes which act as the conductive material and fluorine-based rubber solvent.
The use of such printable conductive ink can help in the development of sportswear which measures pulse and other biological information for more productive sports training. It can also be used to keep a tab on various heath parameters of patients suffering for ailments which require constant monitoring. In its more evolved forms, the printing technology can be used to collect more complex biological information such as pulse and brain waves.
While the concept is still ages away from achieving the high computational power of the modern digital circuit boards, it may just be the first step towards a revolution in personal computing.
Original source: Nikkei Technology