US 4,444,193 A · Fluid absorbent quantitative test device

Abstract

An absorbent quantitative test device in the form of a flat patch. When placed on the skin of a subject; the device collects a fixed volume of sweat. It is particularly intended to be used in screen testing for cystic fibrosis by measuring the chloride level in sweat and providing a visual indication when the level is in excess of a predetermined concentration. A fill tab indicator undergoes a color change when the fixed volume of sweat has been collected signifying completion of the test. The device includes two concentric circular reaction areas of chemically treated absorbent paper or the like. The sweat sample is introduced into the device at the center of the first or inner circular reaction area which contains a chemical composition capable of reacting with all chloride in the sweat sample below a predetermined concentration value to screen out that amount of chloride. A second or outer ring-shaped reaction area contains a chemical composition which indicates a color change for any chloride reaching it in excess of the predetermined concentration value. The color change in the outer ring-shaped portion thereby provides a quantitative indication of the presence of a concentration of chloride in the subject' s sweat in excess of the predetermined concentration level.

Claims22

Dependent claims

A test device which provides a visual indication of the content of a substance in a fluid in excess of a predetermined amount, comprising:

absorbent means of a predetermined absorbency for absorbing a predetermined volume of fluid, the absorbent means defining first and second reaction areas;
the first reaction area being circular in shape, of a predetermined diameter and including means defining a substantially centrally located inlet to the first reaction area for the introduction of the substance-containing fluid thereto;
the second reaction area being arranged in interconnecting relationship with the first reaction area about the perimeter of the first reaction area whereby fluid introduced into the center of the first area migrates radially outward through the first area and into the second area;
the first reaction area including a composition of predetermined amount which reacts with an initial amount of the substance in the fluid, up to the predetermined amount, so as to preclude any substantial effect of such initial amount of the substance in the second reaction area;
the second reaction area including a composition which undergoes a visual change in appearance upon contact with any of the substance remaining in the fluid after migration of the fluid through the first reaction area to produce a visual change in appearance of at least a portion of the second reaction area upon migration of substance-containing fluid into the second reaction thereby indicating the presence of the substance in the fluid in excess of the predetermined amount.

2 more elements

Dependencies are inferred from the claim text.

Fluid absorbent quantitative test device

Life of this patent

Fluid absorbent quantitative test device

Life of this patent

Abstract

Claims22