An electrocapillary flowmeter usable as a quantitative sweat detector

Abstract

A quantitative sweat detector was devised as part of a noninvasive portable warning apparatus intended for the surveillance of unstable insulin-treated diabetics who may have nocturnal hypoglycemic attacks. The sweat sensor consists of a pair of electrodes embedded in a porous material that is infiltrated under capillary drive by sweat as it oozes out of the skin. It was shown that the detector is almost insensitive to insensible perspiration but undergoes graded variation of impedance as it is filled with sweat. It thus works as a transducer of sweat flux (flow rate through unit skin area) as long as the porous material is not saturated. This device has already proved useful as a hypogycemic alarm and could certainly be used for the measurement of sweating rate in place of more cumbersome devices involving ventilated chambers.