Researchers have developed a soft and flexible thermoelectric generator based on a biodegradable polymer, which can convert temperature differences into electricity. Traditional thermoelectric generators (TEGs) have typically been made from expensive and toxic semiconductor materials such as bismuth telluride and lead telluride, limiting their widespread use. However, the new generator can be easily integrated onto a fabric base, enabling the creation of heat-powered body-worn sensors or disposable face masks that can measure temperature.
TEGs generate electric current through the flow of charges between hot and cold regions. The new generator, developed by scientists from the Korean Institute of Science and Technology, uses a zebra-stripe-inspired pattern to create a temperature difference between the stripes large enough to generate electricity. The white sheet made from a flexible and biodegradable polycaprolactone polymer is evenly coated with stripes of black polymer. The white stripes reflect sunlight and radiate heat in the infrared range, while the black stripes absorb heat. This creates hot and cold areas on the elastic polymer base. The striped sheet is placed on top of the “silicon nanomembrane”, which is an array of wave-shaped semiconductor nanowires that can stretch without breaking.
The alternating black and white stripes were tested on a sunny day and created a maximum temperature difference of 22°C, generating a maximum power of about 6 microwatts per square meter (µW/m²). While this is sufficient for low-power sensors, it is less than ideal for commercial applications. Using more thermoelectrically efficient materials would increase the power output, but the device’s main advantages of cheapness, elasticity and biodegradability would be lost. The device was also found to completely dissolve into harmless by-products in 35 days when placed in a saline solution.
The new generator’s flexibility and biodegradability make it ideal for a range of applications, including wearable sensors and medical implants. The device can be integrated into fabrics, allowing the creation of wearable sensors that are powered by body heat. It can also be used to create disposable temperature measuring devices for use in hospitals and clinics. The biodegradable nature of the device means that it could be used for temporary implants, such as sutures, that would naturally degrade over time.
While the new generator is not yet suitable for commercial applications, the researchers hope that their work will inspire further development of low-cost, flexible and environmentally-friendly TEGs. With further advances, these generators could help to reduce energy waste by turning heat from appliances and electronics into usable energy, and could have significant applications in a range of industries.
