Abstract: A microfluidic chip device (MCD) and its use for performing miniaturized assays on magnetic microbeads (MMs) are described. The MCD is particularly useful for carrying out miniaturized transcript analysis by aiding affinity capturing (TRAC) assays, including PCR. The MCD comprises at least one reaction chamber with sealable liquid connections and at least one fluidic pillar filter in each chamber. The fluidic pillar filter comprises rods with spacings allowing MMs to pass. The sealable liquid connections feed liquid to the reaction chamber, wherein air bubbles are removed. The liquid stream contacts the MMs, which are manipulated with a magnetic rod. The liquid connections enable trapping of the MMs behind the pillar filters or in the channel, while the liquid is changed.