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The intent of this chapter is to review the use of sol-gel processing of silica and silica-titania optical coatings in recent research by the authors in three different areas: the synthesis of active gradient-index (GRIN) materials by multilayer deposition of erbium-and ytterbiumdoped silica-titania films, the improvement of the optical and morphological qualities of microlens arrays fabricated by laser ablation and the functionalization of polydimethylsiloxane (PDMS) channel preclinical devices. Through the use of sol-gel, layers with specific properties can be produced. In this regard, undoped and erbium-and ytterbium-doped SiO 2-TiO 2 films have been produced and characterized using atomic force microscopy (surface topography evaluation) and spectral ellipsometry (determination of optical constants, thickness and porosity of the films). In a second application, a silica sol has been synthesized to coat microlens arrays fabricated by laser ablation. The deposited layer reduces the surface roughness of the microlens array, which yields the improvement of the contrast and the homogeneity of the foci. Finally, PDMS channels fabricated with laser technologies and soft-lithography methods are coated with a sol-gel-derived silica film to avoid the degradation of the material with organic solvents, and their biocompatibility is studied.

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We report a laser-based process for microstructuring glass materials for microfluidics applications. The hybrid technique is composed of a nanosecond Q-Switch Nd:YVO 4 laser for fabricating the initial microfluidic microstructures on soda-lime glass substrates and a thermal treatment for reshaping and improving its morphological and optical qualities. The proposed technique preserves the advantages of the laser direct-write technique in terms of design flexibility, simplicity, fast prototyping, low cost, and so on. The beam spot size, pulse overlapping, ablation threshold, debris deposition, heating temperature, and time are investigated and optimized for fabricating optimal microfluidics structures on glass. The manufactured chips for circulating tumor cells (CTCs) capture were tested with tumor cells (Hec 1A) after being functionalized with an EpCAM antibody coating. Cells were successfully arrested on the pillars after being flown through the device giving our technology a translational application in the field of cancer research.

In this work, we present a laser-based process for fabricating a cell electrostimulator. The fabrication methodology comprises two laser processes: a pulse laser deposition (PLD) of an aluminum thin film on soda-lime glass and a laser-based selectively removal of the thin film. The laser set-up for PLD consist of Nd:YVO 4 Rofin Power line 20E (1064 nm wavelength, 20 ns pulse width) focused by a lens of 160 mm focal length inside a vacuum chamber to strike a target of the deposited material. The same laser is used for selectively removing the thin film but focused by a lens of 100 mm focal length. The geometry design is made in CAD-like software. Before microfabrication, a thin aluminum layer (1 μm thickness) is deposited on soda-lime glass using the PLD method. In order to assemble the device, the electrical stimulator is placed between two polycarbonate sheets of 1.5 mm thickness. To prevent any contact with the electric circuit, a thin silicate glass (100 μm) is placed over the electrostimulator. Simulations were performed using ANSYS Maxwell software, verifying that the induced electrical field achieves the minimum for cell stimulation.