Femtosecond laser direct writing microfluidic channels inside photosensitive glass

In this study, we report our recent research in fabrication of microfluidic channels inside bulk Foturan photosensitive glass by femtoseond (fs) laser direct writing. First, a latent image of microchannel was written inside the glass using a fs laser. Then, a visible image of microchannel was obtained when the sample was subjected to a programmed thermal treatment. Next, the sample was soaked in a diluted hydrofluoric (HF) solution in an ultrasonic bath. The laser-exposed region was preferentially etched away with an etching selectivity of 20-40 times and finally, a hollow microstructure was formed inside the glass. The size and cross-sectional profile of microfluidic channels are crucial issues that affect the transport, mixture and / or reaction of reagents in micro-total analysis systems (mu-TAS). We therefore focused our effort on studying how laser processing parameters would affect the microchannel size and aspect ratio. By the one continues procedure of hollow structure formation, different configuration of microfluidic chambers and channel structure can be easily integrated in single glass chip without the cumbersome alignment and assembly processes of individual components.