Femtosecond laser machining microfluidic structures inside photosensitive glass for biochemical analysis

摘要

We report our recent research on fabrication of microfluidic structures inside a bulk Foturan photosensitive glass by femtosecond (fs) laser sub-surface machining. The fs laser beam was linearly scanned to create a latent image of a micro-channel inside the glass. Subjected to a programmed thermal treatment cycle and soaking in a diluted hydrofluoric (HF) solution in an ultrasonic bath, the laser-exposed region was preferentially etched away. A hollow micro-channel structure was therefore formed inside the glass. Micro-Raman spectra revealed that the laser-exposed region was converted into crystalline structure, which is etched at a much higher rate than the amorphous structure. The tnicrochannel is normally tapered along the length direction. The width, aspect ratio and the cross-sectional profile of the microchannel were controllable through multiple beam scans at a pitch of a few microns. Post-annealing after HF etching was found to smoothen the hollow structure surfaces to optical finish. The proposed sub-surface fabrication procedure enabled us to create and integrate four microfluidic chambers and channels in the single glass without the need of assembling processes.