As wearable health-monitoring electronics miniaturize and integrate more deeply within our bodies, a critical concern emerges: How do we power them safely and sustainably?
With the surge in wearable and implantable devices, there’s a heightened demand for self-powered electronics. Current on-skin or implantable devices rely predominately on battery power, both rechargeable and non-rechargeable, but this isn’t sustainable. Batteries come with environmental concerns given their toxicity and post-recycling challenges, and size constraints and the need for periodic replacements highlight the need to develop alternatives.
A team of researchers at Khalifa University has turned to the realm of biomimicry and bio-derived materials to develop a biocompatible triboelectric nanogenerator (TENG). Dr. Bushara Fatma, Postdoctoral Fellow, and Dr. Charalampos Pitsalidis, Assistant Professor of Physics, collaborated with researchers from the Indian Institute of Technology Kanpur, to create a green energy harvester using bacterial cellulose to create energy generators that can be used in healthcare wearable applications. They published their results in Nano Energy, a top 1% journal in the field of electrical and electronic engineering.
Triboelectric nanogenerators integrated into clothing or wearable patches harvest mechanical energy from body movements, enabling continuous power for health-monitoring sensors that can track heart rate, breathing, or other vital signs.
Easy to fabricate, cost-effective and highly efficient, TENGs could offer the panacea to the conundrum of battery-driven wearables and implants. However, many TENGs still employ non-environmentally friendly materials that can cause discomfort or even skin infections.
Bacterial cellulose has potential as a triboelectric layer in a TENG. Produced under the right conditions by bacteria, bacterial cellulose offers a web-like morphology, good mechanical strength, breathability, and high surface area, among other beneficial traits. It is also cost-effective and eco-friendly to produce. By chemically modifying bacterial cellulose and introducing nanocoatings, the research team was able to finely tune its triboelectric properties, paving the way for high-performance, bio-friendly TENG devices.
Developing efficient TENGs is only the first part of the process. For integration with the human body, materials must pass the stringent tests of biocompatibility and bioabsorption. Preliminary results suggest bacterial cellulose-based triboelectric devices meet these criteria, opening the door for their use as implants.
Bacterial cellulose also stands out for its stability in aqueous environments — a vital requirement for implants. To showcase its versatility, the research team developed a device capable of harnessing energy from various foot motions.
“This TENG technology provides a unique combination of properties and has the potential to be implemented in wearables electronics and in vivo applications,” Dr. Pitsalidis said. “We are currently working on various cellulose-based materials which are combined with 2D materials like graphene for high-performance TENG devices. Our long term goal is to implement this technology into smart wearable electronics for health monitoring and wound patch applications.”