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.

flex2.jpgScientists 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.

Study of the biofuel cell’s mechanical and electrochemical resistance under 20% stretching in 2D directions. © Xiaohong Chen, Département de chimie moléculaire (CNRS/Université Grenoble Alpes)Image of the wearable biofuel cell applied to the arm, powering a diode attached to the black armband on the forearm. © Xiaohong Chen, Département de chimie moléculaire (CNRS/Université Grenoble Alpes)