Laser micromachining of microchannel branching networks into silicon with a femtosecond fiber laser

We describe rapid prototyping of a micro-channel branching network into silicon wafer with a femtosecond pulsed fiber laser. The branching network is designed as a blood oxygenator. This network bifurcates according to Murray’s Law over 9 generations with depths ranging from 50µm to 320µm, and satisfies the necessity of equal path lengths. In development of such micro-fluidic structures, Minimal thermal damage and associated debris of femtosecond pulses provides better machined quality and resolution than IR nanosecond pulses. In combination with a galvanometric scanning system, overall fabrication speed is increased using a high repetition rate femtosecond laser. Influences of operating parameters, such as the pulse energy, the focal position, the scan speed, and the number of scan passes, on the depth and the surface roughness of micro-channels are investigated. Based on the result, combinations of laser parameters are selected to realize designed branching networks.