System-level design of an RFID sweat electrolyte sensor patch.

Wearable digital health devices are dominantly found in rigid form factors such as bracelets and pucks. An adhesive RFID sensor bandage (patch) is reported, which can be made completely intimate with human skin, a distinct advantage for chronological monitoring of biomarkers in sweat. In this demonstration, a commercial RFID chip is adapted with minimum components to allow potentiometric sensing of mM ionic solutes in sweat, and surface temperature, as read by an Android smart-phone app (in-vitro tests).