Abstract: This invention relates to a cartridge for an immunoassay test. The cartridge comprises (a) a probe well comprising a probe and a cap, the cap being in a closed position to enclose the probe in the probe well, wherein the probe has a bottom tip coated with analyte-binding molecules, (b) a sample well to receive a sample, (c) one or more reagent wells, (d) a plurality of wash wells each containing a first aqueous solution, and (e) a measurement well having a light transmissive bottom, the measurement well containing a second aqueous solution, wherein the openings of the sample well, reagent well, measurement well and wash wells are sealed. The present invention also relates to an apparatus for loading and releasing a probe. The apparatus comprises a push pin and a groove to load and transfer the probe to a plurality of locations, such as different wells in the above-mentioned cartridge, to conduct the immunoassay test.