Chapters authored
Laser-Based Fabrication for Microfluidics Devices on Glass for Medical Applications
We report a laser-based process for microstructuring glass materials for microfluidics applications. The hybrid technique is composed of a nanosecond Q-Switch Nd:YVO4 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.
Part of the book: Advances in Microfluidics
Sol-Gel Glass Coating Synthesis for Different Applications: Active Gradient-Index Materials, Microlens Arrays and Biocompatible Channels
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 ytterbium-doped 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 SiO2-TiO2 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.
Part of the book: Recent Applications in Sol-Gel Synthesis
In Vitro Evaluation of Laser-Induced Periodic Surface Structures on New Zirconia/Tantalum Biocermet for Hard-Tissue Replacement
This study investigates the biological response of zirconia/tantalum biocermet materials with laser-induced periodic surface structures (LIPSS) generated using a femtosecond laser working at 1030 nm wavelength. LIPSS were formed by laser radiation slightly above the applied threshold fluence. LIPSS features were characterized using techniques such as atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). LIPSS were generated in this study by applying femtosecond pulses with 500 fs pulse duration at a high-repetition rate to smooth-polished zirconia/tantalum biocermet surfaces, with an original roughness value of 3.8 ± 0.2 and 3.1 ± 0.2 nm, respectively. We have demonstrated in vitro that LIPSS are an efficient option to increase osteoblastic differentiation of human bone marrow mesenchymal stem cells (hBMSCs) in ZrO2:Ta biocermets. LIPSS created increase cell metabolism statistically (best values in 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay) and decrease inflammatory response to the material (IL-6 and TNF-alpha values). Extracellular matrix production (ECM) is produced in more quantity and cells differentiate to osteoblast easily. These differences are seen from the beginning until the endpoint (day 20).
Part of the book: Laser Ablation
Fabrication of a Cell Electrostimulator Using Pulse Laser Deposition and Laser Selective Thin Film Removal
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:YVO4 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.
Part of the book: Laser Ablation