Forget hunting for a power socket — the heat from your wrist might soon be enough to keep your smartwatch running indefinitely.
A team of Chinese scientists has developed a groundbreaking plastic film capable of converting body heat into electricity with record-breaking performance. The research, published Friday in the journal Science, could transform how we power the wearable devices that have become part of daily life.
As smartwatches, fitness trackers, and medical patches become more widespread, the inconvenience of daily charging is becoming a real friction point. Thermoelectric materials — which convert temperature differences into power through the Seebeck effect — offer a tantalising alternative: harvest the heat your body is already producing.
The problem has always been that the best thermoelectric materials are rigid, heavy, and often toxic. Flexible plastics are lighter and easier to wear, but historically terrible at converting heat to electricity. The fundamental challenge is a molecular contradiction: good thermoelectric materials need to block heat from moving across them while allowing electricity to flow easily. Usually, if a material is good at one, it's good at both — which ruins the energy conversion.
The breakthrough came from a team led by Liu Liyao at the Chinese Academy of Sciences' Institute of Chemistry. They created a 'hierarchical porous structure' — essentially a plastic sponge filled with holes of all different sizes, from nanometers to micrometers.
This chaotic, hole-filled structure acts like a rugged mountain range for heat, making it difficult for heat waves to pass through. Meanwhile, the narrow bridges between the holes force the polymer molecules to line up in neat rows — creating high-speed highways for electrons.
The result? Heat leakage reduced by 72%. Electrical flow increased by 52%.
The new film achieved a 'thermoelectric figure-of-merit' — a measure of conversion efficiency — of 1.64 at around 70°C, shattering the previous record of 1.4 for flexible materials.
In laboratory tests, a piece of film measuring 10cm by 8cm attached to a person's body generated 9 millivolts of electricity. That's small, but researchers estimate that scaling up could power wireless sensors and other ultra-low-power electronics.
Because the material is a type of plastic, it's compatible with industrial printing techniques — meaning it could eventually be produced in massive rolls, like newspapers.
Liu says that with further development, this 'power-generating plastic' could be used for everything from medical sensors to green energy systems — and even power generation in space. 🔋
*Sources: Science journal · China Daily · Chinese Academy of Sciences*
