Claiming a breakthrough in smart fabric comfort and durability through a process that is more environment-friendly, researchers from Washington State University (WSU) have demonstrated a particular 3D ink printing method that performs well even after repeated washings and abrasion tests.
THE RESEARCH by Hang Liu, a textile researcher and associate professor in the Department of Apparel, Merchandising, Design and Textiles, and the corresponding author of the paper—'Flexible and Durable Direct Ink Writing 3D-Printed Conductive Fabrics for Smart Wearables’—which was published in ACS Omega, has the potential for applications in health care, for first responders, in the military and for athletes. Smart fabrics are an emerging trend, offering the promise of clothing items that can perform some of the same tasks as smart watches and other such devices.
- The most recent work on 3D printing focused on the ability of fabrics to sense and monitor information; developing functional smart wearables will also require power source and data transmission technologies, and this research is only one part of the whole smart system.
THE TECH: Direct ink writing 3D printing technology was used to print solutions of polybutylene succinate—a biodegradable polyester that is compatible with natural fibres — containing carbon nanotubes onto two types of fabric.
- The printed fabrics showed excellent electrical conductivity, mechanical strength, gauge factor and stability under repeated strains, and the solution’s ability to penetrate and bond with fibres gave the fabrics an enhanced washability and resistance to abrasion.
- Tests on printed fabrics for tensile strength, electrical conductivity, their ability to function as motion sensors, and other qualities revealed that the fabrics continued to perform well after 20 cycles of washing and drying, and the surfaces did not scratch or crack after 200 cycles of abrasion testing or 500 cycles of tensile cyclic testing.
- The research team also used a biodegradable, nontoxic solvent, Cyrene, for processing, which is more environmentally friendly than commonly used toxic solvents.
THE STUDY was a part of the doctoral dissertation of one of Liu’s students, Zihui Zhao, who was the lead author.
- Liu has been working on various elements of smart fabrics for several years; she developed a fibre with the flexibility of cotton and the electrical conductivity of a polymer that could have use in wearable tech, as detailed in a paper published in 2023.
THE CONTEXT: So far, research in this field has focused on building technological functions into fabrics, without attention to the way fabrics might feel, fit, and endure through regular use and maintenance, such as washing.
- The materials used, or the technology used, generally produced rigid or stiff fabrics. For instance, if it is a T-shirt with 3D printed material for sensing purposes, it would neither give a snug body fit nor be comfortable. Besides, the sensing performance would be compromised.
- Initial methods of developing smart wearables involved gluing, weaving or sewing functional components such as conductive threads or sensors into fabrics. Newer approaches involving printing have shown promise, but have still faced problems with comfort and maintenance.
- The research was funded in part by a grant from the National Science Foundation.
