The formation and elimination of polymer bulges in CO2 laser microfabrication

CO2 laser is a quick and cheap method for the fabrication of microfluidic chip. However, bulges will form at the rim of the laser ablation zone due to the thermal stress induced by great temperature gradient. The bulges will result in bonding problems, microchannels clogging and electrophoresis sample leak. The method to eliminate the bulges still requires further investigation. In this paper, the formation process of the bulges was recorded synchronously. The relationship between laser fabrication parameters and the height of bulge was established. The effects of the extruding direction of the plate on the forming of the bulge were evaluated. A simple method of “two times of laser cutting” is presented to eliminate the bulges. Results showed that the laser fabrication parameters, such as output power of laser beam and laser beam moving speed, have significant influence on the forming of bulge. The height of bulge also has relationship with the extruding direction of the commercial plate. The method of two times of laser cutting is an effective and simple way to eliminate the bulges.