An experimental study was carried out to evaluate the performance of a polydimethylsiloxane (PDMS) based micromixer for heterogeneous immunoassays of insulin. The detection method is based on coupling the highly specific double-antibody sandwich immunoassay with the sensitive chemiluminescence of the Luminol-Hydrogen Peroxide reaction. Both the immune and chemiluminescence reactions are conducted in the micromixer, and the resultant light emission is detected by a highly sensitive photometer. The behavior of the luminol based chemiluminescence is parabolic with respect to time, and the maximum light intensity is used here to represent the output of the reaction. The current results indicate that at an actuation pressure of 15psi, an actuation frequency of 30Hz leads to the best reaction result. At these operating conditions, the detection limit of insulin is about 10^-14mol/L while the total reaction time of the insulin immunoassay in the micromixer is less than 5 minutes. ©2010 IEEE.