Textile Insight

New Research Emerges that Allows Creating Smarter Textiles Faster. By Kathlyn Swantko he current process for developing smart clothes limits researchers and man- ufacturers to using available conductive materials and components, including con- trollers, actuators, and sensor units, which can also alter the feel or performance of the fabric. In comparison, "In-situ" PolySense technology makes it easy to customize and add electrical functionality to everyday fab- rics without affecting the fabric properties. PolySense is the result of a collaboration between researchers at Saarland University in Germany and the Massachusetts Institute of Technology (MIT). Interestingly, the inspi- ration for the PolySense project came from the custom tie-dyed fabrics of the sixties. The history of these tie-dye novelty fabrics can actually be traced back centuries to their early roots in ancient Japanese shibori textiles, a manual resist-dyeing technique to produce different patterns on the fabric. Through Saarland and MIT's new PolySense research project, smart fabrics can be as accessible and easy-to-make as the tradi- tional tie-dyed T-shirt. In polymer chemistry, PolySence uses "in-situ" polymerization. The word "in-situ" means that the polymerization occurs within the fabric itself. This process is different from regular dyeing or common DIY methods where a coating or bonding layer is applied to the surface of the fabric to add custom colors or patterns onto the fabric. "In-situ" polymerization can create elec- trical properties at a specific place on the fabric where the functional properties are needed. This enables the transfer of existing dye-based technologies to the creation of electrically functional textiles. The process renders the fabric electrically conductive, sensitive to stretching and pressure, and communicates the change in the electrical resistance properties of the textile. With the "in-situ" PolySense method, the fabric is soaked in a chemical "dye" prepa- ration bath, which applies the functional technology to the individual fibers within the fabric. The process is easy to replicate, and can be concluded within an hour. The pro- cess begins with the fabric being immersed in a mixture of water and Pyrrole for about 10 minutes. Then, iron chloride is added to the chemical bath mixture, which creates a chemical reaction. To complete the polymerization process, the textile is stimulated through a 30-minute wash procedure, in which polymer nanocomposites are developed from nanoparticles. When the fabric is removed from the solution, each indi- vidual fiber of the fabric has been completely wrapped in conductive polymer chains, making the fabric electrically conductive. Project Goals Jürgen Steimle, computer science professor at Saarland University and a leader on the project, explains, "Instead of just attaching electronic components onto the surface of the fabric, our goal is to integrate interactive functionalities directly into the fibers of textiles." Existing approaches in the production of smart textiles are complicated and can influence the original characteristics of the material. The new PolySense polymerization method makes it possible to convert textiles into e-textiles and garments, without affecting the fabric's original properties. The process also offers new options for quick and versatile experimentation with new forms of e-textiles and their integration into IT devices. "Especially for devices worn on the body, it is important that these devices don't minimize or restrict the movement of the wearer, while at the same time have the ability to process high-resolution input signals," says Paul Strohmeier, one of the initiators of the project and a scientist in Steimle's research group. l T EDUCATION | SAARLAND UNIVERSITY & MIT Making PolySense of E-Textiles Kathlyn Swantko, president of the FabricLink Network, created www.TheTechnicalCenter.com for Industry networking and marketing of specialty textiles, and www.fabricklink.com for consumer education involving everything fabric. Contact: kgswantko@fabriclink.com Polymerized glove that can digitally capture hand movements. Photo: Oliver Dietze For more information: Saarland University's and MIT's PolySense research, contact, Cedric Honnet, honnet@mit.edu, MIT, Media Laboratory. textileinsight.com January/February 2021 ~ Textile Insight • 33

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