Many powerful processors, sensors, and other electronic components are now inexpensive enough to be discarded after a brief period of use. This accessibility naturally opens up many new opportunities for technology to be incorporated into our lives, yet for a variety of reasons, the potential has not been fully realized. One of the most prominent examples of disposable electronics in today’s world is electronic vape pens. These are hardly the sort of things that science fiction of the past — which is now nearly within reach — has promised us.
Aside from the disappointing real-world applications, these devices bring to mind another important point that we must consider as we move forward. In much the same way that discarded vape pens litter city streets today, other disposable electronics can be expected to do the same in the future. And since these devices are typically loaded with toxic chemicals and materials that are not biodegradable for hundreds or thousands of years, it will be a massive problem as the market for disposables grows — at least without substantial innovation in this area.
Strips of SWEET textiles (📷: Marzia Dulal)
We might get to a brighter future in which cheap, wearable electronics can monitor our health, increase our productivity, or enhance our entertainment yet, however. A team led by researchers at the University of Southampton and UWE Bristol has demonstrated a technique called Smart, Wearable, and Eco-friendly Electronic Textiles (SWEET) that makes it possible to produce functional electronic textiles that rapidly biodegrade in an environmentally-friendly manner when they are no longer needed. But while in use, they are durable, soft, and comfortable to wear.
At the core of the team’s design is Tencel, a biodegradable and renewable textile substrate derived from wood pulp that serves as the fabric’s base. Tencel was chosen not only for its eco-friendly properties but also for its softness, comfort, and resource-efficient production process, which recovers 99 percent of the water and solvents used.
The active sensing components of SWEET are made from graphene and PEDOT:PSS, two conductive materials that are both eco-friendly and high-performing. Graphene offers significant advantages over traditional non-biodegradable metals like silver and copper, as it is lightweight, flexible, and has a lower environmental footprint. PEDOT:PSS, a water-based polymer, mixes conductivity with biodegradability, enhancing the performance of the sensing layer. These materials are precisely deposited onto the textile using an inkjet-printing technology. This technique allows for direct, mask-free patterning with minimal material waste and exceptional resolution.
Samples after four months of being buried in soil (📷: Marzia Dulal)
The researchers fabricated swatches of the textile with inkjet-printed graphene and PEDOT:PSS-based electrodes and integrated them into wearable gloves to test their ability to measure electrocardiogram signals and skin temperature. These gloves were worn by five volunteers during the trials, with the sensors attached to their skin to capture measurements continuously. The SWEET electronic textiles reliably captured the targeted physiological signals at industry-standard accuracy levels, demonstrating their potential for real-world applications. Furthermore, the flexibility of the materials allowed the sensors to maintain conductivity even during movement, ensuring consistent performance.
To evaluate the biodegradability of the textile, samples were buried in the soil. Over a four-month period, the fabric lost 48 percent of its weight and 98 percent of its strength, demonstrating its ability to break down relatively quickly and effectively in natural conditions. The researchers also analyzed the soil microbial community around the buried samples and confirmed that the decomposition process did not negatively impact the environment.
To be certain, advancements will need to be made in other areas as well to build a fully biodegradable wearable electronic device. But this is an important step in the right direction. It could set us on a path toward a more connected future without the negative environmental impacts that would entail today.
