University of Cincinnati professor Jason Heikenfeld and US Air Force Research Laboratory’s Joshua Hagen are developing a perspiration sensor patch to monitor electrolytes, metabolites and other biomarkers.

The patch currently includes a sodium sensor, a voltage meter, a communications antenna, microfluidics, and a controller chip that’s externally powered by a smartphone. It is printed onto a flexible substrate and coated with a sweat-porous adhesive so that it could stick to the skin. In tests, this patch performed as well as the benchtop electrolyte-sensing systems used by doctors to test for cystic fibrosis.

Digital signal processing and algorithms to analyze the raw electrical measurements of biomarkers in sweat must still be improved. But a physical-exertion sensor patch is a near reality, about to be tested on hundreds of people.