Wearable Sensor System for Detection of Lactate in Sweat

TLDR

Increased development of wearable sensors for physiological monitoring has spurred interest in detecting biochemical indicators of health and performance. The study reports a wearable sensor system for non‑invasive detection of excreted human biomarkers in sweat and demonstrates its use with an organic electrochemical transistor to monitor lactate concentration. The system is a thin, flexible Kapton patch (2.5 × 7.5 cm) that attaches to the skin, is controlled via NFC, charged wirelessly, and streams data to a smartphone app; it uses a low‑profile socket for a sensing element that can be swapped, and the authors optimized sensor performance by varying electrode materials, immobilization techniques, and operating voltages. The OECT sensor showed high sensitivity to lactate but its sensing range is limited to concentrations below about 1 mM.

Abstract

Abstract Increased development of wearable sensors for physiological monitoring has spurred complementary interest in the detection of biochemical indicators of health and performance. We report a wearable sensor system for non-invasive detection of excreted human biomarkers in sweat. The system consists of a thin, flexible, kapton patch (2.5 × 7.5 cm) that can be coated with adhesive and affixed to the skin. The system can be controlled by a cell phone via a near-field communications protocol, charged wirelessly, and the data can be downloaded and displayed in a smart phone app. The system is designed such that the sensing element plugs into a low-profile socket, and can easily be removed and replaced as needed due to saturation or aging effects. As a demonstration case, we examined using an organic electrochemical transistor (OECT) within this system to monitor lactate concentration. Several different methods for optimizing the sensor performance were compared, including altering electrode materials, employing various immobilization techniques, and tailoring operating voltages. Resulting functional response of the lactate oxidase enzyme was compared as a function of the sensor variables. The OECT sensor was shown to have high sensitivity to lactate, however the sensing range is limited to lactate concentrations below approximately 1 mM.