A system for detecting analytes in a test sample, and a method for processing the same, is provided. The system includes a cartridge reader unit that has a control unit and a pneumatic system, and a cartridge assembly that prepares the samples with mixing material(s) through communication channels. The assembly has a memory chip with parameters for preparing the sample and at least one sensor (GMR sensor) for detecting analytes in the sample. The assembly is pneumatically and electronically mated with the reader unit via a pneumatic interface and an electronic interface such that the parameters may be implemented via the control unit. The pneumatic system is contained within the unit and has pump(s) and valve(s) for selectively applying fluid pressure to the pneumatic interface of the assembly, and thus through the communication channels, to move the sample and mixing material(s) through and to sensor. The control unit activates the pneumatic system to prepare the sample and provide it to the sensor for detecting analytes, and also processes measurements from the sensor to generate test results.