New conductive ink makes your clothing smarter

 

A new conductive ink can be applied to clothing and other textiles in a single-step printing process, thereby turning fabrics into sensors and wearable electronics (Credit: Someya Laboratory) A new single-step printing process uses an elastic conducting ink to turn clothing and other textiles into flexible, wearable electronic devices or sensors. Researchers at the University of Tokyo developed the ink, which remains highly conductive even when stretched to more than three times its original length. They believe it has applications in sensors built into sportswear and underwear and that it could be part of a shift toward more comfortable wearable electronics. The ink contains a mix of silver flakes, organic solvent, fluorine rubber, and fluorine surfactant. It can be applied with the same convenience of a Voltera V-One and other desktop printed ink-based paper and plastic circuits. And unlike another recent research project that produced flexible circuits using nanoparticle liquid-metal ink, the Japanese researchers' solution requires just a single step – print the ink onto the surface and you're done. It works in one step because the silver flakes self-assemble at the surface of the printed pattern, which gives the material high conductivity. As a proof of concept, the researchers used their ink to print a muscle activity sensor onto a stretchable cloth, with the electrodes printed on both sides and the wiring printed only on the external side of the material. This wristband muscle activity sensor could measure the electrical potential of the muscle(s) beneath it over an area of 16 sq cm (2.5 sq in) thanks to its nine electrodes placed 2 cm (0.8 in) on a 3 by 3 cm grid. The researchers hope that their technique helps make wearable devices more comfortable and widespread. The future of technology, as we've reported before, may be all about molding electronics to your body and integrating sensors in everything you wear. A paper describing the research was published in the journal Nature Communications Source: University of Tokyo

New conductive ink for electronic apparel

 

Thu, 06/25/2015 - 10:45am University of Tokyo Electrodes, wires, and via holes can be printed by a single step printing process. The muscle activity sensor was produced by printing once on each side of the material's surface.  Image: 2015 Someya Laboratory University of Tokyo researchers have developed a new ink that can be printed on textiles in a single step to form highly conductive and stretchable connections. This new functional ink will enable electronic apparel such as sportswear and underwear incorporating sensing devices for measuring a range of biological indicators such as heart rate and muscle contraction. Current printed electronics, such as transistors, light-emitting diodes and solar panels, can be printed on plastic or paper substrates, but these substrates tend to be rigid or hard. The use of soft, stretchable material would enable a new generation of wearable devices that fit themselves to the human body. However, it has proved difficult to make an ink that is both highly conductive and elastic without a complicated multi-step printing process. Now, Prof. Takao Someya's research group at the Univ. of Tokyo's Graduate School of Engineering has developed an elastic conducting ink that is easily printed on textiles and patterned in a single printing step. This ink is comprised of silver flakes, organic solvent, fluorine rubber and fluorine surfactant. The ink exhibited high conductivity even when it was stretched to more than three times its original length, which marks the highest value reported for stretchable conductors that can be extended to more than two and a half times their original length. Using this new ink, the group created a wrist-band muscle activity sensor by printing an elastic conductor on a sportswear material and combining it with an organic transistor amplifier circuit. This sensor can measure muscle activity by detecting muscle electrical potentials over an area of 4x4 square centimeters with nine electrodes placed 2 cm apart in a 3x3 grid. "Our team aims to develop comfortable wearable devices. This ink was developed as part of this endeavor," says Someya. "The biggest challenge was obtaining high conductivity and stretchability with a simple one-step printing process. We were able to achieve this by use of a surfactant that allowed the silver flakes to self-assemble at the surface of the printed pattern, ensuring high conductivity." Source: University of Tokyo