| Femtosecond laser ablation has interesting characteristics for micromachining, notably non-thermal interaction with materials, high peak intensity, precision and flexibility. In this dissertation, the potential of femtosecond laser ablation for fabrication of biomedical and electronic devices is studied. In a preliminary background discussion, some key literature regarding the basic physics and mechanisms that govern ultrafast laser pulse interaction with conductive materials and dielectric materials are summarized. In the dissertation work, results from systematic experiments were used characterize laser ablation of ITO (Indium Tin Oxide), stainless steel (hot embossing applications), polymers (PMMA, PDMS, PET, and PCL), glass, and fused quartz. Measured parameters and results include ablation threshold, damage threshold, surface roughness, single- and multiple-pulse ablation shapes and ablation efficiency. In addition to solid material, femtosecond laser light interaction with electrospun nano-fiber fiber mesh was analyzed and studied by optical property measurements. Ablation of channels in nano-fiber mesh was studied experimentally. Internal channel fabrication in glass and PMMA polymers was also demonstrated and studied experimentally. In summary, it is concluded that femtosecond laser ablation is a useful process for micromachining of materials to produce microfluidic channels commonly needed in biomedical devices such as micro-molecular magnetic separators and DNA stretching micro arrays. The surface roughness of ablated materials was found to be the primary issue for femtosecond laser fabrication of microfluid channels. Improved surface quality of channels by surface coating with HEMA polymer was demonstrated. |
