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At the Advanced Textiles Conference in October in Charlotte, N.C., Anil Kircalianli, head of automation, Orbital Composites (OC), discussed the important role of textiles as a driver for sustainability, particularly in footwear design. Kircalianli argued that the company’s use of 3D printing and robotic manufacturing has created a more sustainable and efficient means of making typically expensive composites, including large scale applications such as airplane wings and wind generator blades, which are not recycled, he said.
“The need for composites at large scale and low cost is at an all-time high,” Kircalianli said. Furthermore, most composites are thermosets, which he said is also not sustainable, and it’s not just in terms of money or environmental issues. It’s also the time needed to make them. Wind turbine blades, for example, are essentially made by hand.
Robots, though, are cheap, flexible and compact. “We need a new paradigm for composites manufacturing,” he said. “The way to do this is with automation and robotics.”
It was a partnership with Lore, a small Seattle-based startup, that instigated the development of a 3D-printed, hard-shelled, high-performance road bike shoe. Using scan-to-print carbon technology featuring OC’s robotic 3D printing platform, the LoreOne shoe is customized to each cyclist’s individual foot shape and printed with continuous fiber composites.
The design increases power transfer and pedaling efficiency via a more direct connection between rider and bicycle when compared to conventional bike shoes. Kircalianli says the complexity of the shoe required creating a flexible micro-factory to produce it.
Comfortable and effective wearables
In her presentation at the Advanced Textiles Conference, Erin Parker, Mississippi State University graduate research assistant, addressed the issue of bringing together designers, developers and engineers to make e-textile wearables that better address their customers’ needs. E-textiles, she stressed, can be made into comfortable and effective wearables for applications in a variety of market segments, but it’s important to understand the particular needs of each one.
Using the phrase “athlete personas,” she discussed four types of “athletes” who may use wearables—sports, tactical, at-risk athlete, and industrial—to make the point that each type has its own concerns. For example, “Sports athletes can be very superstitious,” Parker said, which affects their priorities and decisions concerning their interest in using wearables. This means that a willingness to trust in the data is among the considerations for the sports athlete.
A tactical athlete, such as a soldier, would more likely be concerned about security issues, effective placement of sensors, and high-risk or dangerous conditions. An at-risk athlete could have a range of needs, depending on the individual challenges of the wearer. It’s also important that the wearable is user friendly.
In an industrial setting, the wearer must conform to company operations, but companies, “either don’t know what data they need, or they know, and they feel any wearable will do,” she said. Workers, however, are concerned about how data will be used and may get suspicious of their employer’s motivation.
Otherwise, ergonomics is an important factor, as workers often perform small, repetitive-motion tasks. “Consider how workers already work, so they are comfortable with the wearable,” she said.
Regardless of the type of wearer, she stressed that “the more you can integrate the technology in the garment so it can’t be seen or even felt, the more likely it will be accepted.”
3D printing on textiles
Stratasys, an innovator in 3D printing technology, presented and exhibited at IFAI Expo for the first time this year. The technology itself is around 35 years old, but the recent move to 3D printing onto a textile substrate with the FabriX Innovation Kit takes it to the next level of access and usability.
Colton Mehlhoff presented the technology at the AT conference, with the printer and sample fabrics showcased at the Stratasys booth. The direct-to-textile 3D printing uses the Stratasys TechStyle 3D printer that is capable of printing up to 2 m2 on a range of flat textile substrates up to 2.5mm thickness including carbon fiber, flexible polymers, mylar and netting.
With 600,000 colors, it offers full color, and translucent and transparent options, with the possibility to embed electroconductive materials during the printing process by pausing and placing.
Until now, 3D printing has largely been hard once cured during the production. What this process offers is greater flexibility in the softness and density of the print, improving its drape and lightness. Apparel and footwear designers have already made creative use of the technology. The smart and advanced textile sector may also find it useful in future developments.
Commercializing wearables
The e-textiles focus at IFAI Expo 2022 was directed towards innovation, both new products and, notable this year, was the high interest in advances aimed at reducing barriers to commercialization.
The German Fiber and Fabric Research Institute (DITF) showcased both with their sensorial yarn and invisible ink developments at their booth on the show floor, and Dr Reinhold Schneider gave a presentation on textile-based sensors and electrical switches made using printing technology at the Advanced Textiles Conference.
The market demand for integrated electronics in textiles is wide ranging and includes Global Positioning Systems (GPS), displays, audio, heating and sensing technologies. Wearers and their demands and needs can be very different, as is their use, life expectance and function.
However, what is commonly shared is the need for comfort and a soft handle. Inherent to most fabrics produced for apparel, the process of silk-screen or ink-jet printing sensors and actuators can compromise these qualities adding stiffness, for example. The user expectation is that the e-textile and wearable not just have the electronics integrated, but that this be done seamlessly so that the garment is indistinguishable from clothing not made with e-textiles.
Inkjet printing was the main focus of Dr Schneider’s presentation, but he began by offering some comparisons between inkjet and silk screen printing looking at capacitive sensing switch technology. He pointed out that inkjet printing offers the benefit of speed with the capability to print up to 250 square meters per minute, while screen printing is closer to 90.
Considering more digital production and the digital factory, inkjet can be integrated more seamlessly. However, it is not without its challenges, including finding the right viscosity for the ink to avoid clogging the print nozzles during printing.
Electro-conducting inkjet inks combine electrically conductive materials such as particles, metal salt and reducing agent, electro-conducting polymers, binders, thermal and UV-curable, then additives. It is the additives, humectants in particular, that offer control of the viscosity, and by extension the ability of the printer to produce e-textiles to scale for commercialization.
Selection and preparation of the textile, then protection of the print are important factors as described by Dr Schneider. A smooth rather than highly textured fabric is more suited to inkjet printing, with the application of a pre-treatment ensuring that the conductive ink sits on the surface rather than be absorbed into the fabric. A final coating provides protection from damage, which adds to its longevity.
The applications extend from textile-based switches to a heating element, motion sensing and luminescent textile 7-segment textile display. In offering solutions to issues around e-textile printing, the industry is moving closer to greater commercialization, which will benefit the whole sector.
Dr. Marie O’Mahony is an industry consultant, author and academic and an academic at the Royal College of Art (RCA), London. She is a frequent contributor to Textile Technology Source.
Janet Preus is senior editor of Textile Technology Source. She can be reached at janet.preus@textiles.org.