Effective methods for fabricating trapezoidal shape microchannel of arbitrary dimensions on polymethyl methacrylate (PMMA) substrate by a CO2 laser

The typical triangular-shaped microchannels fabricated by CO2 laser-based microchanneling of polymethyl methacrylate yield low performance in heat sinks, chemical reactors, and other microfluidic devices. Trapezoidal and rectangular microchannels are more commonly used and desired. To fabricate high-quality trapezoidal microchannels using a CO2 laser on polymethyl methacrylate substrates, a two-pass fabrication method is introduced using the offset ratio of 45% to yield a clean cross section. To determine the optimal process parameters to achieve trapezoidal microchannels of desired dimensions, the effects of process parameters were further investigated and groups of equations were derived based on nonlinear regression models. A microfluidic chip was fabricated to compare the performance of triangular and trapezoidal microchannels of the same cross sectional area. The results demonstrated the superior performance of the trapezoidal microchannel fabricated using two-pass fabrication. This indicates that the two-pass fabrication method is a viable rapid and economic solution for fabrication of high-quality microchannels on polymethyl methacrylate-based devices.