Fabrication of trapezoidal cross-sectional microchannels on PMMA with a multi-pass translational method by CO2 laser

Abstract

CO2 lasers with a wavelength of 10.6 μm are often used to produce PMMA microchannels, as non-metallic materials have a strong absorption capability at this wavelength. Generally, triangular cross-section microchannels have been fabricated by conventional laser ablation method due to the Gaussian distribution of laser intensity. In many cases, the traditional method cannot meet the requirements of the microfluidic chips’ manufacture. In this paper, a multi-pass translational method is introduced. The method based on the lateral heat-affected zone (HAZ) formed by single ablation and multiple ablation with its width as the translation distance. The multi-pass translational method not only produces a clean bottom like the static multi-pass method but can modify the cross-sectional topography to produce a clean trapezoidal microchannel. In this research, the topography of microchannel is evaluated by introducing a new parameter "S", the variations in surface roughness and HAZ. Furthermore, the width and the depth of microchannels via laser translational writing are studied by analytical modeling. The experimental results confirmed that the multi-pass translational method is a quick and economical way of fabricating high quality trapezoidal microchannel on PMMA for microfluidic devices application.