Fabrication of microfluidic devices by using a femtosecond laser micromachining technique and μ-PIV studies on its fluid dynamics

Microfluidic devices with trapezoidal and triangular cross sections and with multiple channels are fabricated with commercially available sodalime glasses by using both femtosecond laser micromachining and glass direct thermal bonding methods. The fluid dynamics of the devices are investigated as a function of the flow rate, the channel depth, and the channel's geometry by using micro-particle image velocimetry measurements. All the observations are in good agreement with numerical calculations. The introduction of a smaller micro-channel array into the middle of a rather larger fluidic channel caused the fluid to mix, even when the fluids had very low Reynold's number of 2∼3. The numerical calculations for multi-channel devices show that the efficient mixing of the fluids in the micro channel is due to complex phenomena, such as mutual interference of fluids with different momenta and the viscosity effect of a material adjacent to the surface.