This paper introduces a wireless, passive, conformable sweat sensor sticker for measuring sweat loss volume and conductivity under clothing. The sticker uses a laser-ablated microfluidic channel and a resonant sensor, wirelessly interrogated by a handheld vector network analyzer. Sweat conductivity and volume are determined from the peak transmission loss magnitude and frequency, respectively. A four-person study assessed sensor variance due to tissue heterogeneity and sensor-reader orientation.

Adam R Carr, Yash H Patel, Charles R Neff, Sadaf Charkhabi, Nathaniel E Kallmyer, Hector F Angus, Nigel F Reuel