A dermal patch to be worn on the skin for increasing the concentration of an analyte expressed through the skin in perspiration to a conveniently measurable level. Included are patches and methods of using such patches to determine the quantity of an analyte in a given volume of perspiration, to determine a subject's sensitivity to an allergen, to allow an analyte to be detected with conventional detection systems, and to dissolve the structural components of a patch to facilitate analyte detection.