A research team led by the University of Southampton and UWE Bristol has shown wearable electronic textiles (e-textiles) can be both sustainable and biodegradable.
A new study, which also involved the universities of Exeter, Cambridge, Leeds and Bath, describes and tests a new sustainable approach for fully inkjet-printed, eco-friendly e-textiles named 'Smart, Wearable, and Eco-friendly Electronic Textiles', or 'SWEET'.
Findings are published in the journal Energy and Environmental Materials .
E-textiles are those with embedded electrical components, such as sensors, batteries or lights. They might be used in fashion, for performance sportwear, or for medical purposes as garments that monitor people's vital signs.
Such textiles need to be durable, safe to wear and comfortable, but also, in an industry which is increasingly concerned with clothing waste, they need to be kind to the environment when no longer required.
Professor Nazmul Karim at the University of Southampton's Winchester School of Art, who led the study, explains: "Integrating electrical components into conventional textiles complicates the recycling of the material because it often contains metals, such as silver, that don't easily biodegrade. Our potential ecofriendly approach for selecting sustainable materials and manufacturing overcomes this, enabling the fabric to decompose when it is disposed of."
The team's design has three layers, a sensing layer, a layer to interface with the sensors and a base fabric. It uses a textile called Tencel for the base, which is made from renewable wood and is biodegradable. The active electronics in the design are made from graphene, along with a polymer called PEDOT: PSS. These conductive materials are precision inkjet-printed onto the fabric.
The researchers tested samples of the material for continuous monitoring of human physiology using five volunteers. Swatches of the fabric, connected to monitoring equipment, were attached to gloves worn by the participants. Results confirmed the material can effectively and reliably measure both heart rate and temperature at the industry standard level.
Dr Shaila Afroj, an Associate Professor of Sustainable Materials from the University of Exeter and a co-author of the study, highlighted the importance of this performance: "Achieving reliable, industry-standard monitoring with eco-friendly materials is a significant milestone. It demonstrates that sustainability doesn't have to come at the cost of functionality, especially in critical applications like healthcare."
The project team then buried the e-textiles in soil to measure its biodegradable properties. After four months, the fabric had lost 48 percent of its weight and 98 percent of its strength, suggesting relatively rapid and also effective decomposition. Furthermore, a life cycle assessment revealed the graphene-based electrodes had up to 40 times less impact on the environment than standard electrodes.
Marzia Dulal from UWE Bristol, a Commonwealth PhD Scholar and the first author of the study, highlighted the environmental impact: "Our life cycle analysis shows that graphene-based e-textiles have a fraction of the environmental footprint compared to traditional electronics. This makes them a more responsible choice for industries looking to reduce their ecological impact."
The ink-jet printing process is also a more sustainable approach for e-textile fabrications, depositing exact numbers of functional materials on textiles as needed, with almost no material waste and less use of water and energy than conventional screen printing.
Professor Karim concludes: " Amid rising pollution from landfill sites, our study helps to address a lack of research in the area of biodegradation of e-textiles. These materials will become increasingly more important in our lives, particularly in the area of healthcare, so it's really important we consider how to make them more eco-friendly, both in their manufacturing and disposal."
The researchers hope they can now move forward with designing wearable garments made from SWEET for potential use in the healthcare sector, particularly in the area of early detection and prevention of heart-related diseases that 640 million people (source: BHF) suffer from worldwide.
