Patent ID: 8142722

Claim:
A test element in combination with an associated electronic tester for determining a characteristic of an aqueous solution, the combination comprising: the tester comprising a test element receiving port at least partially defined by a pair of opposed walls of a housing of the tester, with the walls extending upwardly from and juxtaposed about a test element placement member with at least a portion of the placement member being transparent to an interrogating radiation produced by the tester, the test element receiving port being attached to the opposed walls of the housing to create a seal isolating an interior of the housing from an exterior environment, including from aqueous solution on the test element, a source of the interrogating radiation disposed in the interior of the housing for illuminating the test element when positioned on the test element placement member, and a sensor disposed in the interior of the housing to detect interrogating radiation reflected from the illuminated test element, the test element comprising: an opaque substrate; a first side of the opaque substrate comprising a non-reflective surface; and a test pad attached to the first side of the opaque substrate and comprising a reagent responsive in color to a characteristic of an aqueous solution and disposed to have a portion flattened against the test element placement member; a radiation guide member disposed between the test element placement member and both the source of interrogating radiation and the sensor, the radiation guide member comprising a wall that does not transmit the interrogating radiation, with the radiation guide member at least partially defining a first passageway transmitting the interrogating radiation from the source of interrogating radiation to the flattened portion of the test pad and further defining a second passageway transmitting the reflected interrogating radiation from the flattened portion of the test pad to the sensor; wherein the opaque substrate, the radiation guide wall and the non-reflective surface are configured to block transmission of ambient light to the sensor and to direct reflections of radiation from the test pad to the sensor during interrogation of the test pad by the tester when the test element is placed into the test element receiving port with the test pad disposed flat against the test element placement member.