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Microfluidic devices provide a platform with wide ranging applications from environmental monitoring to disease diagnosis. They offer substantive advantages but are often not optimized or designed to be used by nonexpert researchers. Microchannels of a microanalysis platform and their geometrical characterization are of eminent importance when designing such devices. We present a method that is used to optimize each microchannel within a device using high-throughput particle manipulation. For this purpose, glass-based microfluidic devices, with three-dimensional channel networks of several geometrical sizes, were fabricated by employing laser fabrication techniques. The effect of channel geometry was investigated by employing an optical tweezer. The optical trapping force depends on the flow velocity that is associated with the dimensions of the microchannel. We observe a linear dependence of the trapping efficiency and of the fluid flow velocity, with the channel dimensions. We determined that the highest trapping efficiency was achieved for microchannels with aspect ratio equal to one. Numerical simulation validated the impact of the device design dimensions on the trapping efficiency. This investigation indicates that the geometrical characteristics, the flow velocity, and trapping efficiency are crucial and should be considered when fabricating microfluidic devices for cell studies. [ABSTRACT FROM AUTHOR]

Abstract Cladding waveguides are fabricated in Yb,Na:CaF 2 crystal by applying femtosecond laser inscription. Waveguide properties are investigated in terms of guiding behaviors and confocal micro-Raman characterizations. In addition, under 946 nm excitation, visible cooperative up-conversion emissions at 478 nm induced by Yb 3 + ion pairs are observed while other visible bands are detected owing to the impurities of Er 3 + and Tm 3 + ions. Highlights • Cladding waveguides are fabricated in Yb,Na:CaF 2 by femtosecond laser inscription. • Low propagation losses and single-mode waveguides are obtained. • Modification mechanism is revealed by investigating the confocal μ -Raman properties. • Visible cooperative up-conversion emissions are achieved in the waveguides. [ABSTRACT FROM AUTHOR]

We report on the fabrication of dual-line waveguides with low propagation losses and single-mode guidance in Pr:CaF 2 crystals by applying femtosecond laser inscription. In contrast to the typical highly elliptic modes previously reported in dual-line waveguides, the guiding mode obtained in our work is highly-localized with a near-circular profile at wavelength of 633 nm. The investigations on confocal micro-photoluminescence and micro-Raman imaging enable us to illustrate the effect of different femtosecond laser filamentations on the localized refractive index change in Pr:CaF 2 crystals. In company with the mode simulation by finite element method, we further reconstruct the refractive index distribution of the fabricated waveguides. Our results indicate that highly-localized refractive-index increment caused by compressive stress between the lower parts of the filaments is the main mechanism for waveguiding, whereas the damage-induced refractive-index reductions at filaments and in the region between the upper parts of the filaments are responsible for the strong light confinement in both horizontal and vertical directions. • Dual-line waveguides with low propagation losses are fabricated in Pr:CaF 2 by applying FLI. • The waveguides possess single-mode guidance with near-circular mode profile. • Micro-spectral imaging reveal the effect of fs-laser on the localized RI change. • RI is reconstructed based on micro-spectral imaging and finite element method. • The simulated modal profile shows an excellent agreement with the experimental data. [ABSTRACT FROM AUTHOR]