Wet Interface Technologies for Wearable Sweat Sensors

Biosensors for noninvasively monitoring the physiological information from the compounds in externally secreted bodily fluids have been developed to support the realization of daily healthcare. Sweat, which is easily accessible from the human skin surface, is one of the most expected bodily fluids that contain promising biomarkers of some diseases. However, the development of the easy and repeatable sampling method of at-rest sweat is one of the biggest issues to be solved for achieving daily monitoring of the concentration of sweat components. In this chapter, we describe the basic physiology of perspiration and its components and then summarize the current methods for sweat collection. In particular, the promising method for non-invasive sweat collection using hydrogel touchpad-based wet interface, and the sweat sensors implementing them are summarized to introduce and discuss the recent advances and issues of this type of sensor for at-rest sweat-based non-invasive diagnosis.