Rapid prototyping of glass-based microfluidic chips utilizing two-pass defocused CO2 laser beam method

A method is proposed for the scribing of glass substrates utilizing a commercial CO2 laser system. In the proposed approach, the substrate is placed on a hotplate and the microchannel is then ablated using two passes of a defocused laser beam. The aspect ratio and surface quality of the microchannels formed after the first and second laser passes are examined using scanning electron microscopy and atomic force microscopy. The observation results show that the second laser pass yields an effective reduction in the surface roughness. The practicality of the proposed approach is demonstrated by fabricating a microfluidic chip for formaldehyde concentration detection. It is shown that the detection results obtained for five Chinese herbs with formaldehyde concentrations ranging from 5 to 55 ppm deviate by no more than 5.5 % from those obtained using a commercial macroscale device. In other words, the results confirm that the proposed defocused ablation technique represents a viable solution for the rapid and low-cost fabrication of a wide variety of glass-based microfluidic chips.