A cartridge assembly for preparing a test sample and sensing analytes therein using a sensor, the cartridge assembly comprising: a sample processing card comprising: an injection port for receiving the test sample within a body of the card; at least one metering chamber for receiving the test sample injected into the injection port; a mixing material source (260, 265) for introducing one or more mixing materials to the at least one metering chamber; communication channels fluidly connecting the injection port and the mixing material source to the at least one metering chamber; and at least one output port, fluidly connected to the at least one metering chamber via channels, for delivering the test sample and the one or more mixing materials to the sensor; and a substrate attached to the sample processing card, the substrate having associated therewith: the sensor for sensing analytes in the test sample, the sensor being configured to receive the test sample and the one or more mixing materials via the at least one output port of the sample processing card; electrical contact portions configured to establish an electrical connection with a reader unit; and a memory chip for storing information related to processing of the test sample within the sample processing card; wherein the cartridge assembly further comprises a pneumatic interface comprising at least one pneumatic control port and a corresponding communication channel fluidly connected to the at least one metering chamber of the sample processing card, the pneumatic interface configured for connection to an off-board pneumatic system of the reader unit, the pneumatic interface configured to enable application of positive and negative pressurized fluid to the sample processing card to move the test sample and one or more mixing materials within the communication channels and to the sensor, and characterised in that the memory chip stores a pneumatic system protocol that includes steps and settings for selectively applying pressure to the pneumatic interface upon connection with the reader unit and thus delivering at least the test sample from the sample processing card to the sensor. a sample processing card comprising: an injection port for receiving the test sample within a body of the card; at least one metering chamber for receiving the test sample injected into the injection port; a mixing material source (260, 265) for introducing one or more mixing materials to the at least one metering chamber; communication channels fluidly connecting the injection port and the mixing material source to the at least one metering chamber; and at least one output port, fluidly connected to the at least one metering chamber via channels, for delivering the test sample and the one or more mixing materials to the sensor; an injection port for receiving the test sample within a body of the card; at least one metering chamber for receiving the test sample injected into the injection port; a mixing material source (260, 265) for introducing one or more mixing materials to the at least one metering chamber; communication channels fluidly connecting the injection port and the mixing material source to the at least one metering chamber; and at least one output port, fluidly connected to the at least one metering chamber via channels, for delivering the test sample and the one or more mixing materials to the sensor; and a substrate attached to the sample processing card, the substrate having associated therewith: the sensor for sensing analytes in the test sample, the sensor being configured to receive the test sample and the one or more mixing materials via the at least one output port of the sample processing card; electrical contact portions configured to establish an electrical connection with a reader unit; and a memory chip for storing information related to processing of the test sample within the sample processing card; the sensor for sensing analytes in the test sample, the sensor being configured to receive the test sample and the one or more mixing materials via the at least one output port of the sample processing card; electrical contact portions configured to establish an electrical connection with a reader unit; and a memory chip for storing information related to processing of the test sample within the sample processing card; wherein the cartridge assembly further comprises a pneumatic interface comprising at least one pneumatic control port and a corresponding communication channel fluidly connected to the at least one metering chamber of the sample processing card, the pneumatic interface configured for connection to an off-board pneumatic system of the reader unit, the pneumatic interface configured to enable application of positive and negative pressurized fluid to the sample processing card to move the test sample and one or more mixing materials within the communication channels and to the sensor, and characterised in that the memory chip stores a pneumatic system protocol that includes steps and settings for selectively applying pressure to the pneumatic interface upon connection with the reader unit and thus delivering at least the test sample from the sample processing card to the sensor.