Near-IR nanosecond laser direct writing of multi-depth microchannel branching networks on silicon

Multi-depth microchannel network is fabricated on silicon using near-IR nanosecond laser direct writing followed by chemical etching. An 11-level branching network, for which the depth ranges from 20 to 200 μm, is designed and fabricated to be used as a mold for PDMS replica. The bifurcation of the microchannels is designed according to Murray's law so that the total cost function is minimized. The detailed fabrication procedure and parameters are presented, and method of roughness control using both laser processing parameters and etching parameters are discussed. The efficient manufacturing of such microchannels with minimal roughness can pave new roads for realizing microdevices with multi-depth microchannels. Such devices have proven use in environmental/biomedical applications such as artificial lungs.