Wearable textile-based sensor for sweat sodium chloride monitoring applications

Continuous monitoring of physiological analytes like sweat is extremely beneficial in fields such as healthcare and physical fitness. Commercially available physiological monitors have good working quality, but they are unpleasant and cumbersome. Here, we proposed a textile-based flexible, low-cost, easy-to-manufacture impedimetric sensor based on layered assembly for sweat monitoring applications. This proof-of-concept model explores the changes in the impedance of textile sensors due to variations in quantity and concentrations of saline concentrations. Initially, the textile capacitive sensor was fabricated by sandwiching a textile between perforated copper electrodes. The surface property of the selected fabric was characterized using standard SEM and drop shape analyzer. Later, the performance of fabricated sensor was evaluated using an impedance analyzer for different concentrations of saline in the range of 0.3 - 0.9% and at certain intervals for 1 h. Permeable structure and high wettability (water contact angle similar to 25 degrees) of selected textile fabric indicated its high suitability for sweat sensing. For the given geometry of developed sensors, 900 mu l of saline solution and 60 min drying time at 37 degrees C, were the optimum volume for completely wetting and the duration for completely drying the textile sensor, respectively. In addition, the impedance variation was linear (R2 similar to 0.862), and the sensor showed good reproducibility. Its sensitivity and limit of detection were 128.6 Omega/% saline concentrations and 0.334% saline concentration, respectively. The fabricated sensor demonstrated similar device behavior in both laboratory and real-time testing. We believe that the proposed textile-based sensor is highly suitable for future non-invasive health monitoring applications.