Fabrication of Microfluidic Tesla Valve Employing Femtosecond Bursts

Expansion of the microfluidics field dictates the necessity to constantly improve technologies used to produce such systems. One of the approaches which are used more and more is femtosecond (fs) direct laser writing (DLW). The subtractive model of DLW allows for directly producing microfluidic channels via ablation in an extremely simple and cost-effective manner. However, channel surface roughens are always a concern when direct fs ablation is used, as it normally yields an RMS value in the range of a few µm. One solution to improve it is the usage of fs bursts. Thus, in this work, we show how fs burst mode ablation can be optimized to achieve sub-µm surface roughness in glass channel fabrication. It is done without compromising on manufacturing throughput. Furthermore, we show that a simple and cost-effective channel sealing methodology of thermal bonding can be employed. Together, it allows for production functional Tesla valves, which are tested. Demonstrated capabilities are discussed.