Optimizing laser-based micro-cutting for PMMA microfluidic device fabrication: thermal analysis and parameter optimization

Abstract Laser processes have gained popularity in microfluidic device fabrication. This study aims to determine the optimal parameters for laser-based micro-cutting to achieve the desired width, depth, profile, and material removal, considering the thermal properties of PMMA. A CNC CO2 laser was used, and 29 trials tested various speed and power combinations. Two theoretical models based on trial results focused on depth and width. COMSOL Multiphysics FEA software estimated surface temperature. Theoretical depth estimation matched experimental data more accurately when the P/S ratio was below 0.15 and the scanning speed was set at 500 mm/s or 750 mm/s. At 500 mm/s, width estimation was most accurate, up to 30 W. At 750 mm/s, experimental width exceeded predictions. Material removal increased proportionally with increasing P/S ratio, but beyond a threshold of 0.15, material removal remained nearly constant despite rising heat input. Laser-cut track shape varied, resembling a ‘U’ at lower and a ‘V’ at higher ratios. The groove shape transitioned from ‘U’ to ‘V’ when the temperature surpassed 1200 K. A V-shaped groove required a temperature exceeding 1500 K. Optimization confirmed a microchannel depth of 0.197 mm, width of 0.256 mm, and ‘U–V’ channel shape achievable at 30 W and 200 mm/s scanning speed, with a surface temperature of 1325 K.