Diagnostic device

A method, comprising:

• applying a sample solution to an assay device, the assay device comprising:
• a sensor stack comprising panels disposed in face-to-face contact with each other, each panel including a hydrophobic region and a hydrophilic region, the hydrophilic regions co-operatively defining a sample flow path for migration of a fluid sample through the sensor stack, and the hydrophobic regions each including an arrangement of entangled fibers that are coated with a polymeric material to define interconnected interstitial passages between the fibers, thereby providing at least one path through the panels that allows gas flow therethrough and repels the intrusion of the fluid sample into the hydrophobic region;
• and
• a wicking layer on a surface of the sensor stack to draw the fluid sample through the sample flow path;
• migrating the sample solution through the sample flow path;
• separating the wicking layer from the sensor stack to expose the surface of the sensor stack;
• and
• applying a color solution to a color zone on the surface that chemically reacts with an analyte captured in the sensor stack and thereby produces a detectable chromogenic product indicating the presence or absence of an analyte in the sample.

A method of making a diagnostic device using an elongate web of a fibrous material comprising a first major surface and a second major surface, wherein the web has a thickness extending from the first major surface to the second major surface, and a first edge and a second edge, the web comprising a plurality of adjacent web regions extending from the first edge to the second edge, wherein at least a portion of the web regions are separated from adjacent web regions by border regions, the method comprising:

• applying a first portion of a hardenable hydrophobic polymeric ink composition to the first major surface of the web in at least one web region, wherein the first portion of the hardenable hydrophobic polymeric ink composition wicks a distance less than the thickness from the first major surface of the web toward the second major surface of the web;
• applying a second portion of the hardenable hydrophobic polymeric ink composition to the at least one web region on the second major surface of the web, wherein the second portion of the hardenable hydrophobic polymeric ink composition wicks from the second major surface of the web toward the first major surface of the web, wherein the first portion of the hardenable hydrophobic polymeric ink composition meets the second portion of the hardenable hydrophobic polymeric ink composition to form a hydrophobic area comprising the hardenable hydrophobic polymeric ink composition and a hydrophilic area substantially free of the hardenable hydrophobic polymeric ink composition;
• at least partially hardening the hardenable hydrophobic polymeric ink composition in the hydrophobic areas of the at least one web region to provide a hydrophobic ink on fibers of the fibrous material and interconnected interstitial passages between the fibers, the interconnected interstitial passages between the fibers providing at least one open ink-free path between the first major surface of the web and the second major surface of the web that allows gas flow therethrough and repels the intrusion of a fluid sample into the hydrophobic areas;
• and
• folding the web along the border regions to form a stack of panels, each of the panels including registered hydrophilic areas that define a sample flow path therebetween.