Cotton fabric generates electricity from humidity; powers LEDs, devices

Scientists have developed a novel cotton fabric coated with two polymers—polypyrrole and polydopamine—that can generate continuous electricity by harvesting moisture from the air. Polypyrrole absorbs sunlight and converts it into heat, accelerating water evaporation on one side of the fabric, while polydopamine reflects light and retains moisture on the other side. This asymmetrical coating creates a persistent moisture gradient that drives ion transport through the cotton fibers, enabling stable electrical output without batteries or external power sources. The manufacturing process involves polymerizing pyrrole directly on untreated cotton fibers to form a conductive, light-absorbing layer, followed by coating half the fabric with an ultra-thin polydopamine film that creates a thermal contrast. Under sunlight, the temperature difference between the two sides sustains water evaporation and ion flow. Multiple fabric units connected in series produced voltages up to 1.18 V under simulated sunlight and 0.72 V at night, powering LED lights continuously for over 24 hours