Wearable Conductive Textile with Controllable Piezoresistivity and Transiency for Vibrotactile Haptics Systems

Electronic waste is an exponentially increasing environmental issue, especially for wearable devices, due to their widespread diffusion into society and short life cycle.[1] To promote their enormous benefits, e.g., in assisting visually impaired individuals and making them more sustainable, biobased and/or biodegradable materials should be used instead of traditional components.<br/>Thus, we functionalized cotton with diverse conductive coatings made by mixing biodegradable binders such as polybutylene adipate terephthalate and environmentally friendly solvents such as water, alcohol, and anisole with carbon-based nanomaterials. Doing that, we obtained isotropic or anisotropic electrical resistance change with bending, depending on the coating composition, the textile twill, and the stress direction. The obtained materials were functioning either as a bendable-compliant electrode or a tunable piezoresistor. Transiency of the coatings was tuned, changing the binder type and composition, allowing the coating to shift from entirely transient within minutes to resisting washing cycles for hours without losing its electrical conductivity. By controlling the material composition and deformation direction, these versatile green electrical conductors may be used in various applications, such as sensors, actuators, or human motion sensing.<br/>Towards such vision, we engineered a specific class of inks to propose the first ECO-friendly wearable vibroTACtile device (Eco-Tac).[4] The design of Eco-Tac includes integration on a cotton T-shirt through the biodegradable conductive ink forming electrical tracks, a flexible commercially available solar panel, and the vibrotactile haptic device itself. As such, the feasibility of using a sustainable energy source to supply power to the device and the possibility of using biodegradable materials in its manufacturing are demonstrated. An experiment with twenty blindfolded subjects is conducted, reporting the device’s potential for assistance in manipulation tasks. Overall, the results of this work represent the first significant step towards creating wearable and sustainable haptic devices with green electronics and mechatronics approaches.<br/><br/><b>References:</b><br/>[1] Dulal, M.; Afroj, S.; Ahn, J.; Cho, Y.; Carr, C.; Kim, I.-D.; Karim, N. Toward Sustainable Wearable Electronic Textiles. ACS nano 2022.<br/>[2] Orts Mercadillo, V.; Chan, K. C.; Caironi, M.; Athanassiou, A.; Kinloch, I. A.; Bissett, M.; Cataldi, P. Electrically Conductive 2D Material Coatings for Flexible and Stretchable Electronics: A Comparative Review of Graphenes and MXenes. Advanced Functional Materials 2022, 2204772.<br/>[3] Cataldi, P.; et al., M. A Green Electrically Conductive Textile with Tunable Piezoresistivity and Transiency. Advanced Functional Materials 2023, 33 (30), 2301542.<br/>[4] Arbaud R. et al., Towards Sustainable Haptics: A Wearable Vibrotactile Solar-Powered System with Biodegradable Components. Advanced Materials Technology 2024.