A Novel Fabrication Procedure for the Preparation of Polymethyl Methacrylate Lab-on-a-Chip Substrates

Modification of a minicomputer numerical controller with a low cost diode laser for fabrication of polymethyl methacrylate chips has been demonstrated. The maximum power of diode laser was 5 W at 808 nm. The scanning speed was 1.0 to 10.0 mm s−1 by the movement of x and y stages. The patterns of microchannels on the chip were designed using drawing software and then applied to software that controlled the operation of the controller. The parameters that affected the channel depth, width, and smoothness were studied by varying the laser power and speed of polymethyl methacrylate sheets with surface area of 4.0 × 6.0 cm2 and thickness of 0.1 cm. The optimum conditions were used to fabricate microchannels on each sheet giving different depths and widths over the range of 74 µm to 554 µm and 147 µm to 393 µm, respectively. The most appropriate conditions for polymethyl methacrylate chip fabrication were 5 W and 3 mm s−1 for the laser diode power and the speed, respectively. The optimal dimensions of the microchannel on the polymethyl methacrylate sheet were 226 µm in width and 202 µm in depth based on sensitivity, reproducibility, and low background signals. The microchannels were sealed with a polymethyl methacrylate cover plate by thermal bonding. The resulting chips were tested for iron(III) determination in water based on microreverse flow analysis.