Continuous measurement of sweating by electrical conductivity

Summary form only given. A method of measuring sweating was proposed in which pure water was perfused through a chamber having a small opening facing the skin surface. Sweating was detected by the change in electrical conductivity of the water, as measured by electrodes placed at the outlet of the flow channel. Ion-free isotonic sucrose solution was perfused with a flow rate of about 2 ml/min. When a bolus of ion was loaded at the opening, the 90% response time was about 0.12 s. For the observation of single-sweat-gland activity, a special chamber was prepared in which the area of the opening to the skin was about 0.2 mm 2. A quantitative sudomotor axon reflex test (QSART) was performed using a chamber having a concentric well filled by acetylcholine solution, which can be transported into the tissue by iontophoresis. It was confirmed that mental sweating could be monitored successfully. Whilst only the amount of electrolyte is measured in this method, the mental sweating responses observed were quite similar to those recorded by an air-ventilated chamber. Axon reflex sweating during QSART was also successfully observed using the chamber.