Femtosecond laser microfabrication of 3D structures in Foturan glass

Currently, high throughput manufacture of Lab-on-a-chip devices integrated with both microoptics and microfluidics faces serious challenges, including assembly and packaging. Because of their different physical properties and functions, the optical and the fluidic elements are often first separately fabricated on different substrates, and then assembled into a single Lab-on-a-chip device. The alignment between the microoptical and microfluidic components requires micronscale precision. To overcome this difficulty, we recently developed a novel laser microfabrication technique to form 3D hollow structures buried in a photosensitive glass - Foturan. The formation of both the optical and the fluidic structures were completed in a unified fabrication process. The technique is based on femtosecond laser direct writing followed by post-baking and successive chemical etching, completely eliminating the assembling procedures such as alignment, fixation, stacking, and bonding that are inherent in traditional 3D microprocessing techniques. In this paper, we describe the fabrication of a broad variety of hollow structures in Foturan glass, and the integration of these structures to build functional micro-devices. Furthermore, we will discuss how to control the fabrication resolution in three dimensions by developing novel beam focusing schemes to generate isotropic focal spot shapes inside the transparent materials.