Abstract: Moisture may build up inside an alcohol monitor that is securely attached to a human subject due to the inlet air from the subject's skin surface which constantly emits water vapor in the form of insensible skin perspiration. As the warm moist air which has very high humidity flows along the air flow path through decreasing temperatures within the alcohol monitor, moisture will be removed from the air through condensation. The condensation problem is solved by lowering the humidity level in the air sample by mixing the very humid air sample from the body with less humid ambient air, which increases the dew point for condensation. Increasing the dew point in the air sample means that there must be a greater change in temperature along the air flow path of the air sample in order to cause the moisture in the air sample to condense and become water.

Abstract: Moisture buildup inside an alcohol monitor that is securely attached to a human subject is due to the inlet air from the subject's skin surface, which constantly emits water vapor in the form of insensible skin perspiration. As the warm moist air flows along the air flow path through decreasing temperatures within the alcohol monitor, moisture will be removed from the air through condensation. The present invention solves this condensation problem by first simplifying the air flow path, eliminating barriers that can trap water. Second, additional changes to the air flow path take advantage of gravity, allowing water to drain out of the alcohol monitor. Third, by better balancing the volume of air sample between the sample collection chamber and the fuel cell sample chamber, the total volume of air taken in is reduced, resulting in an overall reduction in the volume of potential moisture introduced into the alcohol monitor.