Optical biosensor based on whispering gallery mode excitations in clusters of microparticles

Abstract

A new concept for an optical biosensor based on whispering gallery mode (WGM) excitations in clusters of spherical microresonators is presented. Clusters of microresonators offer the advantage to exhibit specific WGM spectra that can be considered as their fingerprint. Therefore, individual clusters can be traced throughout an experiment even without knowledge of their precise positions. Polyelectrolyte adsorption onto clusters of 10μm polystyrene spheres is monitored in situ. It is shown that the WGMs shift to the same amount as those of a single microresonator and thus sensitivity does not depend on the number of microresonators present in the cluster.

Giant resonant light forces in microspherical photonics

“…52 Microspheres with resonant WGMs can be used as building blocks of delay lines, 30 ultranarrow spectral filters, laser-resonator arrays, 53 waveguides, [29][30][31][32] focusing devices, 54,55 microspectrometers 56 and sensors. 57 Such spheres are also required in biomedical applications 58 where they are used as markers, fluorescent labels and spectral fingerprints. …”

Whispering gallery mode biosensor operated in the stimulated emission regime

“…6 Now, we were able to show that these systems are also applicable to the detection of thin films of adsorbates in an aqueous environment. In this study on biosensing in the stimulated emission regime, we used somewhat larger particles than in previous work [18][19][20] because of their higher stability against bleaching. Future activities will therefore aim at a reduction in the sensor diameter, thus further improving the detection limit and versatility of low-Q WGM sensors.…”

“…On this basis, recently also microresonators of a few micrometers in diameter made from silica particles or PS beads have been applied as miniature remote refractometers 7,8 and biosensors. [18][19][20] In particular, the increased free spectral range ␦ of such smaller resonators enables mode detection and distinction by diffraction optics and therefore allows the excitation of a whole range of modes, for example, by means of the fluorescence emission of embedded semiconductor quantum dots 21 or fluorescent dyes 11 ͑cf. Fig.…”

Self-organized internal architectures of chiral micro-particles

“…The method used to create the micro-particles with controlled internal chiral architectures presents great flexibility providing several advantages connected to the acquired optical and photonics capabilities and allowing to envisage novel strategies for the development of chiral colloidal systems and materials. © 2014 Author (s Micro and nano-scale particles have recently attracted considerable attention in several research areas, as optical trapping and manipulations, [1][2][3][4][5] microfluidics and optofluidics, [6][7][8][9][10] sensors, [11][12][13][14][15][16] photonics, photonics crystals, [17][18][19] colloidal and materials science. [20][21][22][23][24][25][26][27] Strategies to create multifunctional micro-particles even with dissymmetric properties, like Janus particles, have been successfully explored.…”