Hybrid integration in photosensitive glass using 3D femtosecond laser micromachining and its commercial potential

By shrinking a roomful of laboratory equipments and packing them into a palm-size chip, single Lab-on-a-chip devices are capable of performing a variety of chemical and biological analyses with reduction of reagent consumption, waste production, analysis time and labor cost. However, difficulties in packaging and assembly have been major challenging issues in the manufacture of Lab-on-a-chip devices. To tackle this problem, we recently combined the 3D femtosecond (fs) laser microfabrication technique and the multifunctionality of a photosensitive glass called Foturan. This development enables us to form various true 3D hollow micro structures inside or on the surface of Foturan glass with one continuous processing. Using this technique, a variety of micro-chemical reactor structures, including microchannels, microchambers, and microvalves, have been fabricated inside Foturan glass with an approximate spatial resolution of 10μm. Since the microstructuring of Foturan glass by fs laser is a non-ablative photochemistry processing, the fabricated internal surface is smooth and free of debris and cracks. The smooth surfaces can thus be used as microoptical elements to effectively reflect/deflect light beams. For the purpose of further smoothening the etched internal surface, we applied an additional annealing to the samples after etching by which the average roughness was brought down to ∼0.8nm on the laser scanned surface. Thus, we are able to fabricate microoptical mirrors, micro-beam splitters, freestanding optical fibers, and microoptical lenses in the glass. We have also demonstrated the functions of all these structures using a He-Ne laser. Functional micro-devices such as microfluidic dye lasers were successfully fabricated by integrating the microoptical and microfluidic components inside the glass, and lasing action was confirmed by analyzing the emission spectra at different pumping powers. The commercial potential of this technique is also discussed in this paper.