Abstract: An analyzer system includes a motor, a dock coupled to the motor, and a cartridge held in the dock. The cartridge includes a fluid circuit configured to receive a sample, isolate a target analyte of the sample, and collect a quantity of a first label that is proportional to a quantity of the target analyte in the sample. The fluid circuit includes a sample port configured to receive a sample, a mixing chamber in fluid communication with the sample port, and a fluid inlet port in fluid communication with the mixing chamber. The fluid circuit includes an isolated path extending from the fluid inlet port to the mixing chamber. The system also includes a fluid delivery line configured to be coupled to the fluid inlet port so as to deliver fluid to the cartridge through the fluid inlet port and push the fluid along the isolated path toward the mixing chamber.