Avanços em Engenharia Automobilística
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Novel concepts and materials for microfluidic optical devices

Mitsunori Saito and Yusuke Itai

Energy concentration is essential to create compact, efficient microfluidic optical devices. Polyethylene glycol (PEG) is a suitable fluid for this aim with its bipolarity (molecular dissolvability), nonvolatility, and high index of refraction (waveguiding). Its illustrious feature is a bistability in the phase transition process; i.e., a mixture of two PEG types (molecular weight: 300 and 2000), for example, takes both the liquid and solid phases in the temperature range of 2???38 °C. One can use this phase transition to pause a sample flow at a specific position in small channels. The bistability also realizes a rewritable signboard with a PEG droplet array, since both the clear (liquid) and milk-white (solid) states are stable at room temperature. The strong scattering in the solid phase is useful to confine a light beam (photonic localization). Mirrorless lasers, which have been studied extensively with microdroplets, can be constructed with dye-dispersed PEG, since the confined fluorescence induces a stimulated emission. A bistable laser emission has been demonstrated in the phase transition process of the microfluid. The light confinement is also useful to enhance the absorbance of inorganic materials, which hardly absorb excitation or probe light particularly in a microchannel. Scientific experts have as of late created natural inorganic cross breed phosphors with an upgraded excitation effectiveness. Spectroscopic examination of these mixtures needs time-settled estimations, since both fast and moderate cycles happen in natural ligands and metal particles. The time-space transformation ghastly estimation is reasonable for microfluidic gadgets, since a nanosecond goal is achievable with no requirement for an enormous beat laser. For every material devoted to microfluidic applications, inborn microfabrication and explicit physico