Flexible biofuel cell runs on sweat

A new flexible and stretchable device, worn against the skin and capable of producing electrical energy by transforming the compounds present in sweat, has been developed and patented by researchers from the French National Centre for Scientific Research (CNRS) and the University of California San Diego.

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.

CNRS scientists from l’Université Grenoble Alpes, who specialise in bioelectrochemistry, decided to collaborate with a team from UC San Diego, 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.

Study of the biofuel cell’s mechanical and electrochemical resistance under 20% stretching in 2D directions. Image© Xiaohong Chen, Département de chimie moléculaire (CNRS/Université Grenoble Alpes).

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, opening new avenues for the development of wearable electronics powered by autonomous and environmentally friendly biodevices.

Described in the journal Advanced Functional Materials, the cell 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.

Top image caption: The wearable biofuel cell applied to the arm, powering a diode attached to the black armband on the forearm. Image© Xiaohong Chen, Département de chimie moléculaire (CNRS/Université Grenoble Alpes).

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