The e-skin is powered by sweat. (Credit: Caltech)

A researcher has developed an electronic skin that is applied directly on top of real skin. The e-skin, made from soft, flexible rubber, can be embedded with sensors that monitor information like heart rate, body temperature, levels of blood sugar, and metabolic byproducts that are indicators of health, and even the nerve signals that control muscles. It does so without the need for a battery, as it runs solely on bio-fuel cells powered by one of the body’s own waste products.

The fuel cells built into the e-skin absorb that lactate and combine it with oxygen from the atmosphere, generating water and pyruvate, another by-product of metabolism. As they operate, the biofuel cells generate enough electricity to power sensors and a Bluetooth device, allowing the e-skin to transmit readings from its sensors wirelessly.

The biofuel cells are made from carbon nanotubes impregnated with a platinum/cobalt catalyst and composite mesh holding an enzyme that breaks down lactate. They can generate continuous, stable power output (as high as several milliwatts per square centimeter) over multiple days in human sweat.

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