naa a22 4500 510815944 CHVBK 20180411083507.0 cr unu---uuuuu 180411e20130301xx s 000 0 eng 10.1007/s11468-012-9423-8 doi (NATIONALLICENCE)springer-10.1007/s11468-012-9423-8 Refractometric Sensing with Silicon Quantum Dots Coupled to a Microsphere [Elektronische Daten] [Y. Zhi, C. Manchee, J. Silverstone, Z. Zhang, A. Meldrum] Quantum dots (QDs) coupled to an optical microsphere can be used as fluorescent refractometric sensors. The QD emission couples to the whispering gallery resonances of the microsphere, leading to sharp, periodic maxima in the fluorescence spectrum. Silicon QDs (Si-QDs) are especially attractive fluorophores because of their low toxicity and ease of handling. In this work, a thin layer of Si-QDs was coated onto the surface of a microsphere made by melting the end of a tapered optical fiber. Refractometric sensing experiments were conducted using two methods. First, the sphere was immersed directly into a cuvette containing methanol-water mixtures. Second, the sphere was inserted into a silica capillary and the solutions were pumped through the capillary channel. The latter method enables microfluidic operation, which is otherwise difficult to achieve with a microsphere. In both geometries, high-visibility (V = 0.83) modes were observed with Q factors up to 1,700. Using standard signal processing methods applied to the whispering gallery mode (WGM) spectrum, sensorgram-type measurements were conducted using single Si-QD-coated microspheres. The WGM resonances shifted as a function of the refractive index of the analyte solution, giving sensitivities ranging from ~30 to 100nm/refractive index unit (RIU) for different microspheres and a detection limit on the order of 10−4 RIU. Springer Science+Business Media, LLC, 2012 Whispering gallery mode nationallicence Refractometric sensing nationallicence Microsphere nationallicence Silicon quantum dots nationallicence Zhi Y. Department of Physics, University of Alberta, Edmonton, AB, Canada aut Manchee C. Department of Physics, University of Alberta, Edmonton, AB, Canada aut Silverstone J. Department of Physics, University of Alberta, Edmonton, AB, Canada aut Zhang Z. Department of Physics, University of Alberta, Edmonton, AB, Canada aut Meldrum A. Department of Physics, University of Alberta, Edmonton, AB, Canada aut Plasmonics Springer US; http://www.springer-ny.com 8/1(2013-03-01), 71-78 1557-1955 8:1<71 2013 8 11468 https://doi.org/10.1007/s11468-012-9423-8 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s11468-012-9423-8 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Zhi Y. Department of Physics, University of Alberta, Edmonton, AB, Canada aut NATIONALLICENCE 700 1- Manchee C. Department of Physics, University of Alberta, Edmonton, AB, Canada aut NATIONALLICENCE 700 1- Silverstone J. Department of Physics, University of Alberta, Edmonton, AB, Canada aut NATIONALLICENCE 700 1- Zhang Z. Department of Physics, University of Alberta, Edmonton, AB, Canada aut NATIONALLICENCE 700 1- Meldrum A. Department of Physics, University of Alberta, Edmonton, AB, Canada aut NATIONALLICENCE 773 0- Plasmonics Springer US; http://www.springer-ny.com 8/1(2013-03-01), 71-78 1557-1955 8:1<71 2013 8 11468 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer