Interstitial fluid capture device and method of measuring electrolyte levels using same

An interstitial fluid capture device, comprising:

• a main body portion configured for temporary retention in a mouth of a user between an inner surface of a lip of the user's mouth and a forward surface of teeth of the user's mouth, said main body portion having an elongate shape defining a retained, curve shape which extends along a longitudinal axis of the main body portion and includes a curved inner surface which faces, contracts, and contours to the inner surface of the lip when the interstitial fluid capture device is worn and a curved outer surface which faces, contacts, and contours to the forward surface of the teeth when the interstitial fluid capture device is worn, and wherein the curved inner surface and the curved outer surface are co-direction and aligned such that the curved inner surface and curved outer surface define, at least in part, the retianed, curve shape;
• a solution reservoir located within, and defined at least in part by, the main body portion, the reservoir forming an opening along a fluid extraction side of the main body portion comprising the curved outer surface, wherein the main body portion is configured such that, when properly positioned in the mouth of the user, the fluid extraction side of the main body portion and the solution reservoir opening thereof faces the inner surface of the lip of the user, and the semipermeable membrane contacts the inner surface of the lip of the user;
• a solution residing in the solution reservoir of the main body portion, wherein the solution is hypertonic with respect to interstitial fluid present in the lip of a human mouth;
• and
• a semipermeable membrane covering the solution reservoir opening and sealing the hypertonic solution within the solution reservoir, the semipermeable membrane constructed from a material that permits the interstitial fluid from mouth tissue of the user, including through the inner surface of the lip of the user contacting the semipermeable membrane, to be drawn through the semipermeable membrane and into the solution reservoir during use and retained therein, and wherein said semipermeable membrane is penetrable by a test strip to access the interstitial fluid stored therein.