A system for controlling fluid flow movement between a sample receiving pad and a test strip, comprising: a cartridge with a top portion and a bottom portion; a sample receiving pad; a test strip in contact with the sample receiving pad; the sample received pad and the test strip located between the top portion and the bottom portion; the top portion including a hole for receiving a sample; a pinch wall protruding from the top portion and/or bottom portion and sitting on top of the sample receiving pad, the pinch wall compressing the sample receiving pad; the pinch wall comprising: a first portion separating a sample receiving portion of the sample receiving pad from a portion of the sample receiving pad positioned adjacent to the test strip, and a second portion separating the sample receiving portion of the sample receiving pad from a portion of the sample receiving pad positioned away from the test strip; wherein the first and second portions (45B, 45A) of the pinch wall together continuously surround the sample receiving portion of the sample receiving pad; wherein the sample receiving portion of the sample receiving pad that receives the sample thereon is positioned on an opposite side of the pinch wall from the portion of the sample receiving pad positioned away from the test strip, wherein the first portion of the pinch wall compresses the sample receiving pad to a lesser degree than the second portion of the pinch wall, wherein fluid seeps more quickly under the first portion of the pinch wall than under the second portion of the pinch wall, such that the test strip becomes saturated prior to excess fluid being absorbed in the portion of the sample receiving pad away from the test strip such that the test strip does not become flooded, the portion of the sample receiving pad positioned away from the test strip being sufficiently sized to absorb the excess fluid; and characterized in that a dam protrudes from the top portion of the cartridge and is arranged to sit on top of the sample receiving portion of the sample receiving pad, the dam preventing the backflow of fluid from an area near the first portion of the pinch wall. a sample receiving pad; a test strip in contact with the sample receiving pad; the sample received pad and the test strip located between the top portion and the bottom portion; the top portion including a hole for receiving a sample; a pinch wall protruding from the top portion and/or bottom portion and sitting on top of the sample receiving pad, the pinch wall compressing the sample receiving pad; the pinch wall comprising: a first portion separating a sample receiving portion of the sample receiving pad from a portion of the sample receiving pad positioned adjacent to the test strip, and a second portion separating the sample receiving portion of the sample receiving pad from a portion of the sample receiving pad positioned away from the test strip; wherein the first and second portions (45B, 45A) of the pinch wall together continuously surround the sample receiving portion of the sample receiving pad; wherein the sample receiving portion of the sample receiving pad that receives the sample thereon is positioned on an opposite side of the pinch wall from the portion of the sample receiving pad positioned away from the test strip, wherein the first portion of the pinch wall compresses the sample receiving pad to a lesser degree than the second portion of the pinch wall, wherein fluid seeps more quickly under the first portion of the pinch wall than under the second portion of the pinch wall, such that the test strip becomes saturated prior to excess fluid being absorbed in the portion of the sample receiving pad away from the test strip such that the test strip does not become flooded, the portion of the sample receiving pad positioned away from the test strip being sufficiently sized to absorb the excess fluid; and characterized in that a dam protrudes from the top portion of the cartridge and is arranged to sit on top of the sample receiving portion of the sample receiving pad, the dam preventing the backflow of fluid from an area near the first portion of the pinch wall.