Femtosecond laser ablation for microfluidics

We present some applications of femtosecond laser ablation for microfluidics. A doubled Ti:sapphire femtosecond laser (=400 nm; pulse width, 90 fs; pulse energy up to 350 µJ; pulse repetition rate, 1 kHz) is used to microstructure passive microfluidic devices (channels, reservoirs, through-holes) in polymers [polymethyl methacrylate (PMMA), polyimide (PI, Kapton)] and glass (Pyrex). These materials are selected because of their extended use in the fabrication of microfluidic chips. In all cases, channels of some tenths of micrometers are obtained with a good-quality finishing for fluid transport. In the same sense, reservoirs and holes are produced. These latter elements are fabricated in larger dimensions to combine them with channels in some presented prototypes. The well-known feature of ultrashort pulses is that no edge effects are observed because the absence of thermal effects enables a good sealing. For PMMA, polymer bonding technologies are used. For Pyrex, the well-known silicon sealing by anodic bonding is chosen. In both cases, the fabricated prototypes work properly with a good flow behavior and no leakage is observed.