A convenient direct laser writing system for the creation of microfluidic masters

We describe a homebuilt direct laser writing (DLW) system centered on a fluorescence microscope as an alternative means for the creation of microfluidic masters. Such masters are often the starting point of microanalytical platforms and are usually made using transparency masks, which are inexpensive and very convenient. However, these masks can become expensive if features are <25 μm. The linewidth of features made by our DLW system spans from submicron to a millimeter depending on the objective lens, the focal position, the stage speed, and the laser power used. By adjusting these parameters during fabrication, we show that large and small features can be integrated in the same sample. Masters made by DLW were used to create polydimethylsiloxane microfluidic devices and also to perform microcontact printing of alkanethiol monolayers on gold. We also show that registration between sequential patterning steps is readily accomplished and can be used to repair structures or to add features to an existing pattern. The components required to modify a stage-equipped fluorescence microscope into our DLW system are commercially available for under $5000; we contend that this system is a convenient alternative to mask-based lithography for prototyping lab-on-a-chip devices.