Authors:
Dong Hyuck Kam
Jyoti Mazumder
Center for Lasers and Plasmas for Advanced Manufacturing (CLPAM), University of Michigan, Ann Arbor Michigan 48105

Application of laser direct writing to the fabrication of microchannel networks for tissue engineering was presented. A Q-switched Nd:YAG laser with fundamental wavelength was used. Multidepth, multiwidth microstructures on silicon were machined without photolithography-based methods. The molten material inside the microchannel was ejected with a modified assist gas, and thus the volume of laser ablation was increased. The debris build-up due to the strong thermal reaction of silicon to the nanosecond IR laser pulse was cleaned up with chemical wet etching in a mixture of hydrofluoric acid (HF) and nitric acid (HNO₃). The chemical etching of the laser ablated silicon surface was studied to measure the etching rate and to observe the evolution of the surface morphology. Using the laser machined silicon structures as a mold, a poly(dimethylsiloxane) (PDMS) replica was created. Flow visualization was carried out with the patterned PDMS.