Portable electronics: A stretchable and flexible biofuel cell that runs on sweat

A unique new flexible and stretchable device, worn against the skin and capable of producing electrical energy by transforming the compounds present in sweat, was recently developed and patented by CNRS researchers from l'Université Grenoble Alpes and the University of San Diego (USA). This cell is already capable of continuously lighting an LED, opening new avenues for the development of wearable electronics powered by autonomous and environmentally friendly biodevices. This research was published in Advanced Functional Materials on September 25, 2019.

The potential uses for wearable electronic devices continue to increase, especially for medical and athletic monitoring. Such devices require the development of a reliable and efficient energy source that can easily be integrated into the human body. Using "biofuels" present in human organic liquids has long been a promising avenue.

Scientists from the Département de chimie moléculaire (CNRS/Université Grenoble Alpes), who specialize in bioelectrochemistry, decided to collaborate with an American team from the University of San Diego in California, who are experts in nanomachines, biosensors, and nanobioelectronics. Together they developed a flexible conductive material consisting of carbon nanotubes, crosslinked polymers, and enzymes joined by stretchable connectors that are directly printed onto the material through screen-printing.

The biofuel cell, which follows deformations in the skin, produces electrical energy through the reduction of oxygen and the oxidation of the lactate present in perspiration. Once applied to the arm, it uses a voltage booster to continuously power an LED. It is relatively simple and inexpensive to produce, with the primary cost being the production of the enzymes that transform the compounds found in sweat. The researchers are now seeking to amplify the voltage provided by the biofuel cell in order to power larger portable devices.