Optics-Integrated Microfluidic Platforms for Biomolecular Analyses

Abstract

Compared with conventional optical methods, optics implemented on microfluidic chips provide small, and often much cheaper ways to interrogate biological systems from the level of single molecules up to small model organisms. The optical probing of single molecules has been used to investigate the mechanical properties of individual biological molecules; however, multiplexing of these measurements through microfluidics and nanofluidics confers many analytical advantages. Optics-integrated microfluidic systems can significantly simplify sample processing and allow a more user-friendly experience; alignments of on-chip optical components are predetermined during fabrication and many purely optical techniques are passively controlled. Furthermore, sample loss from complicated preparation and fluid transfer steps can be virtually eliminated, a particularly important attribute for biological molecules at very low concentrations. Excellent fluid handling and high surface area/volume ratios also contribute to faster detection times for low abundance molecules in small sample volumes. Although integration of optical systems with classical microfluidic analysis techniques has been limited, microfluidics offers a ready platform for interrogation of biophysical properties. By exploiting the ease with which fluids and particles can be precisely and dynamically controlled in microfluidic devices, optical sensors capable of unique imaging modes, single molecule manipulation, and detection of minute changes in concentration of an analyte are possible.

Analytic model for the complex effective index of the leaky modes of tube-type anti-resonant hollow core fibers

“…Besides guidance mechanisms such as photonic band gap confinement 13 , omnidirectional reflection 14 , 15 or effective medium reflection 16 , 17 , the anti-resonant effect has recently been identified to be highly relevant for future high-performance HCFs, as it enables efficient waveguiding on the basis of a straightforward-to-fabricate microstructure 18 , 19 . The concept of anti-resonant guidance traces back to close-to-unity reflection of dielectric multilayers in the case of near-grazing incidence and has been successfully employed in, e.g., biosensing 20 , 21 or gas analysis 22 using planar anti-resonant reflecting optical waveguides (ARROWs) 23 . Various types of anti-resonant fiber geometries such as the negative curvature 19 , 24 , the double revolver 25 , the single ring 26 , 27 or the hypocycloid core contour 28 designs have been recently implemented, exhibiting low optical losses at mid- and near-infrared 28 , visible, and even UV wavelengths 26 , 27 , 29 , and low susceptibility to bending 30 .…”

Robust polarization active nanostructured 1D Bragg Microcavities as optofluidic label-free refractive index sensor

“…The use of 2D and 3D PCs to determine the RI of liquids and solutions in microfluidic systems has been amply discussed in literature [1,[11][12][13][14][15][16][18][19][20][21] [1,[11][12][13][14][15][16][18][19][20][21]. Other methods based on plasmonic detection have also been proposed.…”

“…The development of multifunctional "lab on a chip" microfluidic systems requires very sophisticated transducers and robust, cheap and reliable interrogation procedures capable of providing reversible and straightforward detection functions. [1] Photonic crystal (PC) detection systems are very common in microfluidics because of their flexibility, non-destructive character and the rich variety of physical principles available for detection. [2,3] These include many examples related to plasmonic detection.…”

Vertically sheathing laminar flow-based immunoassay using simultaneous diffusion-driven immune reactions

“…14 Various microuidics-based immunoassay methods have been developed to address the limitations of conventional assay platforms. They exploited a variety of different approaches, such as the automated lab-on-a-disc devices, 15,16 integration of an optical system in the microuidic devices, [17][18][19] a quantum dot (QD) "barcoding" system, 20,21 and the three-dimensional microuidic connement. 22,23 Despite considerable efforts in the microuidic immunoassay platforms in the past decades, most researches have focused on automation, [24][25][26] increased surface areas, 27,28 improved reporter probes, 29,30 and distinctive detection principles; 31,32 however, the efficient delivery of antibody reagents to the reaction sites has been rarely explored.…”