A test cartridge for use in sample analysis is provided. The test cartridge includes a reservoir card that further includes a reagent that includes living biological cells; and a test cartridge base configured to accept the reservoir card. The reservoir card is configured to interface with a test cartridge base through at least one fluid port. The test cartridge base includes an elliptical reaction chamber having a central axis and an inlet channel connected to the reaction chamber. The inlet channel is positioned above the reaction chamber at an angle of 15-60 degrees above the horizontal and is offset from the central axis of the reaction chamber. Upon introducing a sample to be analyzed into the test cartridge base through the inlet channel, the sample is homogeneously mixed with the reagent while minimizing damage to the living biological cells.