The main goal of this project is to develop novel, unprecedented textiles for garments that provide haptic stimulation. Being textile materials, they open new ways of designing wearable haptics and can be seamlessly integrated into fabrics and garments. They use low voltages, are silent, lightweight, soft and pliable, in contrast to other solutions that most often are hard, bulky, and noisy. Other than vibration motors, this haptic textile accesses receptors of our tactile sensory system that react on soft pressure or stroke.
The basis for these garments are textile muscles made from electromechanically active polymers (EAPs). When low voltage is applied to EAP coated yarns, they contract or elongate depending on the polarity of the applied voltage. Processing these yarns further into textiles multiplies the effect of the contraction and/or delivered force, depending on the textile construction used (weave or knit).
We foresee a huge range of applications in haptic garments: in ergonomics, motor learning in sports, wellness, or rehabilitation, for enhancement of virtual reality in gaming or for training purposes, for people with visual impairment, for stress reduction, social communication, and more.
One result of the project will be a demonstrator showing the potential of the textiles developed for garments with haptic stimulation. A relevant use case serves as concept for the demonstrator. Knowledge of human perception, e.g., how much force creates a sensation, allows to derive requirements for the textiles. The textile development spans from production of electroactive yarns to processing these into textiles. Finally, the fabrication of the demonstrator garment requires the integration of textile, electrical connectivity, sensors, and dedicated control.
Progress per Working Package:
Demonstrator: To show the potential of the developed technology, we will create a demonstrator garment. Relevant use cases were identified by brainstorm sessions, market research, online surveys, and involvement of our Advisory Board. The outcome was categorised based on market- type, feasibility, and target group. The consortium preselected four use cases (posture, navigation for blind, buddy-locator for deaf blind people, and social touch), which were elaborated w.r.t. background, user scenarios, personas, and impact. Aligning requirements derived with the current status of the technology development, the consortium decided to focus on the use case of social touch.
Human perception: We explore when people perceive textile muscles and how they experience it. For the perception part, we developed an experimental setup that simulates textile contraction, including a controllable hardware device, and a series of dedicated sleeves. The setup allows accurate control of the stimuli, for instance, to determine detection thresholds. In addition to this setup using servo motors, also a setup using pneumatic muscles was designed. For the experience part, we developed a semi-structured interview with visuals to make an inventory of the qualities of passive touch. All tools are used in experiments with volunteers starting in 2021.
Electroactive textile: We made yarn muscles by coating commercial yarns such as polyamide, viscose, and polyester with EAP. They were optimized w.r.t. the coating parameters (e.g. using additives), and the thicknesses of the various coating layers. The yarns showed good actuation properties and the performance was considerably enhanced as compared to the pre-WEAFING yarn actuators. Upscaling of the production of coated EAP yarns has been addressed. EAP yarn expands and contracts when stimulated by voltage by expelling or absorbing ions. In order to operate in open-air, ions must be provided to the yarn using ionic polymer gel coatings. These “ionogel” coatings must allow fast motion of ions, to make the yarn reaction fast, must be safe for skin contact, and robust to be compatible with textile production and garment life. We developed UV curable ionogel that can be coated continuously on long yarns, with state-of-the-art ionic conductivities and stretchability above 100%.
The yarn actuators were coated with the ionogels, resulting in yarns that can move in open air. The transition from passive to mechanically active yarns is a paradigm shift for the textile community that requires new textile constructions. This has been explored twofold: i) On-fabric actuation where we investigated the possibilities for coating fabrics with EAPs, studied the fabric characteristics needed, and developed coating methods. ii) In-fabric actuation, where we have developed new textile patterns that enable the integration of actuating yarns and the support the additive effects of actuation. We have for the first time demonstrated that in-air actuated fabrics can be woven on real warped looms. We have developed weaving techniques that enable handling of the yarns while maintaining the integration of the fabric. We have also developed new knitting techniques for handling the yarns.
Actuation: The electroactive textiles developed are a new class of actuators, requiring dedicated control strategies. For their development simulation models of single yarns have been made, and also of actuated knitted and woven fabric. To verify these models, reference setups using pneumatic actuators and shape memory alloy have been developed.
Communication: We developed a multi-media communication and dissemination plan. It tackles scientific peers, industries, in development and applications (Inclusion, Ergonomics, Sports, Medical, Gaming, Labour, Communication, Art/Fashion, and Safety) and end consumers to address market pull and technology push innovation. Over time over 300 live and virtual/online communication and dissemination activities (conferences, workshops, lectures, exhibitions, (scientific) publications, social media posts, videos, press releases, interviews) were received by tens of thousands of people and a potential of millions. So far, a patent analysis uncovered few to none technically similar patents. Some industrial stakeholders already reached out to the consortium for collaboration.
Textile that can be actuated with low voltage is not available yet. Before WEAFING, the working principle was shown for knitted textile coated with EAP in aqueous salt solution. Current progress is that we have developed the first woven fabrics that move in air. Whereas perception is well studied for vibration motors, it is not for pressure. We have developed devices that allows for systematic exploration of the relation between force and perception. Concerning expected results and impact, WEAFING will progress smart systems and (soft) robotics by developing multifunctional electroactive fabrics, using textile fabrication where sensors and actuators are woven or knitted into the fabric. A new form of smart material and new digitized products such as wearable haptic displays will be made possible. The research field of psychophysics will progress by new results for perception of touch. The electroactive fabrics will enable new ways to design smart garments, for applications ranging from health to inclusion, from remote communication to entertainment, and further also for exoskeleton-like suits, or applications in automotive or interior design. With the developed textile actuators and advanced textile fabrication methods, WEAFING generates new opportunities for European textile and smart material industries.