Wearable strain sensor for real-time sweat volume monitoring

Reliably monitoring sweat volume has attracted much attention due to its important role in the assessment of physiological health conditions and the prevention of dehydration. Here, we present the first example of wearable strain sensor for real-time sweat volume monitoring. Such sweat volume monitoring sensor is simply fabricated via embedding strain sensing fabric in super-absorbent hydrogels, the hydrogels can wick sweat up off the skin surface to swell and then trigger the strain sensing fabrics response. This sensor can realize real-time detection of sweat volume (0.15–700 μL), shows excellent repeatability and stability against movement or light interference, reliability in the non-pathological range (pH: 4–9 and salinity: 0–100 mM NaCl) in addition. Such sensor combing swellable hydrogels with strain sensing fabrics provides a novel measurement method of wearable devices for sweat volume monitoring.