Method and apparatus for determination of chemical species in perspiration

DETAILED DESCRIPTION In one aspect, the present invention comprises a dermal patch to be worn on the skin of a subject mammal for quantitatively determining the presence and amount of an analyte in that subject's perspiration.
This dermal patch includes: a fluid permeable support layer in fluid communication with the subject's skin when the patch is worn on the subject's skin, wherein the support layer comprises a rate-limited structure that limits the rate of diffusion of perspiration through the support layer; and an absorbent material in fluid communication with the support layer for collecting non-aqueous components of perspiration which diffuse through the support layer, the support layer being located between the absorbent material and the subject's skin when the patch is worn on the subject's skin.
In a preferred embodiment, a gas permeable layer is located between the absorbent material and the outside of the patch, wherein water and other fluids expressed through the skin of the subject are permitted to escape through the gas permeable layer in their vapor phase to the outside of the patch.
In order to attach a patch to the skin of a subject according to this aspect of the present invention, the gas permeable layer can further include an adhesive composition applied to the outer perimeter of the outer protective layer on the side of the outer protective layer in contact with the skin of the subject.
The gas permeable layer can also be used to form a pooling area between the gas permeable layer and the subject's skin when the patch is worn on the subject's skin.
Such a pooling area is used to collect excess perspiration that is not diffused across the support layer.
In one embodiment, the absorbent material is in fluid communication with the pooling area only through the support layer.
The absorbent material in this aspect of the present invention can be made from various materials, including paper or cotton gauze.
In one embodiment, the collection of an analyte of interest from the perspiration of the subject in the absorbent material is improved by providing the absorbent material with a specific binding partner for the analyte