A rectangular microchannel was fabricated with polydimethylsiloxane (PDMS) material and MnO2 catalysts were deposited on the wall of the microchannel. The growth and detachment process of oxygen bubbles generated by the catalytic reaction of H2O2 solution were recorded by a high speed camera. The effects of reactant concentration and flow rate on bubble growth rate and detachment diameter were also analyzed. The growth and detachment process of bubbles generated on the catalytic surface in the microchannel occurred periodically. Moreover

the bubble growth consisted of two processes

the initial fast growth process and the later slow growth process. Before 3 s

the generated bubbles were in a fast growth period

and reaction kinetics dominated the process. However

after 3s

reaction rate was controlled by diffusion

resulting in the fact that bubble growth rate increased with increasing reactant concentration. In addition

bubble detachment diameter was slightly affected by reactant concentration

while it was significantly affected by reactant flow rate and dropped linearly as Reynolds number increased.