{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,9]],"date-time":"2026-04-09T20:36:26Z","timestamp":1775766986364,"version":"3.50.1"},"reference-count":113,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2017,3,8]],"date-time":"2017-03-08T00:00:00Z","timestamp":1488931200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100000002","name":"NIH","doi-asserted-by":"publisher","award":["1R21MH111109-01"],"award-info":[{"award-number":["1R21MH111109-01"]}],"id":[{"id":"10.13039\/100000002","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Sensitive and rapid label-free biological and chemical sensors are needed for a wide variety of applications including early disease diagnosis and prognosis, the monitoring of food and water quality, as well as the detection of bacteria and viruses for public health concerns and chemical threat sensing. Whispering gallery mode optical resonator based sensing is a rapidly developing field due to the high sensitivity and speed of these devices as well as their label-free nature. Here, we describe the history of whispering gallery mode optical resonator sensors, the principles behind detection, the latest developments in the fields of biological and chemical sensing, current challenges toward widespread adoption of these devices, and an outlook for the future. In addition, we evaluate the performance capabilities of these sensors across three key parameters: sensitivity, selectivity, and speed.<\/jats:p>","DOI":"10.3390\/s17030540","type":"journal-article","created":{"date-parts":[[2017,3,8]],"date-time":"2017-03-08T07:42:58Z","timestamp":1488958978000},"page":"540","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":74,"title":["Label-Free Biological and Chemical Sensing Using Whispering Gallery Mode Optical Resonators: Past, Present, and Future"],"prefix":"10.3390","volume":"17","author":[{"given":"Judith","family":"Su","sequence":"first","affiliation":[{"name":"College of Optical Sciences, Department of Chemistry &amp; Biochemistry, University of Arizona Cancer Center, University of Arizona, Tucson, AZ 85721, USA"}]}],"member":"1968","published-online":{"date-parts":[[2017,3,8]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"e16001","DOI":"10.1038\/lsa.2016.1","article-title":"Label-free detection of single nanoparticles and biological molecules using microtoroid optical resonators","volume":"5","author":"Su","year":"2016","journal-title":"Light Sci. Appl."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"268","DOI":"10.1016\/0003-2697(91)90424-R","article-title":"Immobilization of Proteins to a Carboxymethyldextran-Modified Gold Surface for Biospecific Interaction Analysis in Surface-Plasmon Resonance Sensors","volume":"198","author":"Johnsson","year":"1991","journal-title":"Anal. Biochem."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"71","DOI":"10.1016\/0030-4018(83)90047-0","article-title":"A Simple Fiber Fabry-Perot Sensor","volume":"45","author":"Kersey","year":"1983","journal-title":"Opt. Commun."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"971","DOI":"10.1039\/C4LC01208A","article-title":"Two-dimensional photonic crystals for sensitive microscale chemical and biochemical sensing","volume":"15","author":"Baker","year":"2015","journal-title":"Lab Chip"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"18529","DOI":"10.1364\/OE.19.018529","article-title":"Deterministic design of wavelength scale, ultra-high Q photonic crystal nanobeam cavities","volume":"19","author":"Quan","year":"2011","journal-title":"Opt. Express"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"8629","DOI":"10.1039\/c3cs60128e","article-title":"Photonic crystal fibres for chemical sensing and photochemistry","volume":"42","author":"Cubillas","year":"2013","journal-title":"Chem. Soc. Rev."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"839","DOI":"10.1038\/nature01939","article-title":"Optical microcavities","volume":"424","author":"Vahala","year":"2003","journal-title":"Nature"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"519","DOI":"10.1038\/nature05498","article-title":"Label-free immunodetection with CMOS-compatible semiconducting nanowires","volume":"445","author":"Stern","year":"2007","journal-title":"Nature"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"339","DOI":"10.1038\/nnano.2015.32","article-title":"Inertial imaging with nanomechanical systems","volume":"10","author":"Hanay","year":"2015","journal-title":"Nat. Nanotechnol."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"442","DOI":"10.1038\/nmat2162","article-title":"Biosensing with plasmonic nanosensors","volume":"7","author":"Anker","year":"2008","journal-title":"Nat. Mater."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"203","DOI":"10.1038\/nnano.2011.44","article-title":"Comparative advantages of mechanical biosensors","volume":"6","author":"Arlett","year":"2011","journal-title":"Nat. Nanotechnol."},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Ghali, H., Chibli, H., Nadeau, J., Bianucci, P., and Peter, Y.-A. (2016). Real-Time Detection of Staphylococcus Aureus Using Whispering Gallery Mode Optical Microdisks. Biosensors, 6.","DOI":"10.3390\/bios6020020"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"20701","DOI":"10.1073\/pnas.0808988106","article-title":"Single virus detection from the reactive shift of a whispering-gallery mode","volume":"105","author":"Vollmer","year":"2008","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"5976","DOI":"10.1073\/pnas.1017962108","article-title":"High sensitivity nanoparticle detection using optical microcavities","volume":"108","author":"Lu","year":"2011","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"933","DOI":"10.1038\/nnano.2014.180","article-title":"Single-molecule nucleic acid interactions monitored on a label-free microcavity biosensor platform","volume":"9","author":"Baaske","year":"2014","journal-title":"Nat. Nanotechnol."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1241","DOI":"10.1021\/acsphotonics.5b00142","article-title":"Label-Free Single Exosome Detection Using Frequency-Locked Microtoroid Optical Resonators","volume":"2","author":"Su","year":"2015","journal-title":"ACS Photonics"},{"key":"ref_17","first-page":"e53180","article-title":"Label-free Single Molecule Detection Using Microtoroid Optical Resonators","volume":"106","author":"Su","year":"2015","journal-title":"J. Vis. Exp."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"3347","DOI":"10.1021\/nl401633y","article-title":"Label-free detection of single protein using a nanoplasmonic-photonic hybrid microcavity","volume":"13","author":"Dantham","year":"2013","journal-title":"Nano Lett."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1001","DOI":"10.1080\/14786441008636993","article-title":"CXII. The problem of the whispering gallery","volume":"20","author":"Rayleigh","year":"1910","journal-title":"Philos. Mag."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"100","DOI":"10.1080\/14786440108635067","article-title":"Further applications of Bessel\u2019s functions of high order to the Whispering Gallery and allied problems","volume":"27","author":"Rayleigh","year":"1914","journal-title":"Philos. Mag. Ser. 6"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"42","DOI":"10.1038\/108042a0","article-title":"Whispering Gallery phenomena at St Paul\u2019s Cathedral","volume":"108","author":"Raman","year":"1921","journal-title":"Nature"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"391","DOI":"10.1063\/1.1707320","article-title":"Dielectric resonators","volume":"10","author":"Richtmyer","year":"1939","journal-title":"J. Appl. Phys."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"3019","DOI":"10.1364\/AO.17.003019","article-title":"Narrow resonance structure in the Mie scattering characteristics","volume":"17","author":"Chylek","year":"1978","journal-title":"Appl. Opt."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"1807","DOI":"10.1103\/PhysRev.124.1807","article-title":"Stimulated Emission into Optical Whispering Modes of Spheres","volume":"124","author":"Garrett","year":"1961","journal-title":"Phys. Rev."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"499","DOI":"10.1364\/OL.9.000499","article-title":"Laser-Emission from Individual Droplets at Wavelengths Corresponding to Morphology-Dependent Resonances","volume":"9","author":"Tzeng","year":"1984","journal-title":"Opt. Lett."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"486","DOI":"10.1126\/science.231.4737.486","article-title":"Lasing Droplets\u2014Highlighting the Liquid-Air Interface by Laser-Emission","volume":"231","author":"Qian","year":"1986","journal-title":"Science"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"926","DOI":"10.1103\/PhysRevLett.56.926","article-title":"Multiorder Stokes Emission from Micrometer-Size Droplets","volume":"56","author":"Qian","year":"1986","journal-title":"Phys. Rev. Lett."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"151","DOI":"10.1364\/JOSAB.6.000151","article-title":"Generation and Suppression of Stimulated Brillouin-Scattering in Single Liquid Droplets","volume":"6","author":"Zhang","year":"1989","journal-title":"J. Opt. Soc. Am. B Opt. Phys."},{"key":"ref_29","unstructured":"Barber, P.W., and Chang, R.K. (1988). Optical Effects Associated with Small Particles, World Scientific."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"925","DOI":"10.1038\/nature01371","article-title":"Ultra-high-Q toroid microcavity on a chip","volume":"421","author":"Armani","year":"2003","journal-title":"Nature"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"393","DOI":"10.1016\/0375-9601(89)90912-2","article-title":"Quality-Factor and Nonlinear Properties of Optical Whispering-Gallery Modes","volume":"137","author":"Braginsky","year":"1989","journal-title":"Phys. Lett. A"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"453","DOI":"10.1364\/OL.21.000453","article-title":"Ultimate Q of optical microsphere resonators","volume":"21","author":"Gorodetsky","year":"1996","journal-title":"Opt. Lett."},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Novotny, L., and Hecht, B. (2012). Principles of Nano-Optics, Cambridge University Press. [2nd ed.].","DOI":"10.1017\/CBO9780511794193"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"654","DOI":"10.1109\/JSTQE.2009.2032510","article-title":"Label-Free Biosensor Arrays Based on Silicon Ring Resonators and High-Speed Optical Scanning Instrumentation","volume":"16","author":"Iqbal","year":"2010","journal-title":"IEEE J. Sel. Top. Quantum Electron."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"1104","DOI":"10.1364\/OL.18.001104","article-title":"Strain-Sensitive Elastic-Scattering from Cylinders","volume":"18","author":"Huston","year":"1993","journal-title":"Opt. Lett."},{"key":"ref_36","first-page":"209","article-title":"Microdroplet Missing Resonance Spectroscopy","volume":"1862","author":"Eversole","year":"1993","journal-title":"Laser Appl. Combust. Combust. Diagn."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"373","DOI":"10.1366\/0003702944028254","article-title":"Absorption-Spectroscopy Using Microdroplet Resonance Fluorescence Intensities","volume":"48","author":"Eversole","year":"1994","journal-title":"Appl. Spectrosc."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"654","DOI":"10.1364\/OL.20.000654","article-title":"Excitation of Resonances of Microspheres on an Optical-Fiber","volume":"20","author":"Serpenguzel","year":"1995","journal-title":"Opt. Lett."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"272","DOI":"10.1364\/OL.28.000272","article-title":"Shift of whispering-gallery modes in microspheres by protein adsorption","volume":"28","author":"Arnold","year":"2003","journal-title":"Opt. Lett."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"2408","DOI":"10.1021\/nl100501d","article-title":"Optical Manipulation with Planar Silicon Microring Resonators","volume":"10","author":"Lin","year":"2010","journal-title":"Nano Lett."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"7610","DOI":"10.1364\/OE.15.007610","article-title":"Silicon-on-Insulator microring resonator for sensitive and label-free biosensing","volume":"15","author":"Bartolozzi","year":"2007","journal-title":"Opt. Express"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"76","DOI":"10.1016\/j.optlastec.2015.09.012","article-title":"[INVITED] Optical microfibre devices","volume":"78","author":"Brambilla","year":"2016","journal-title":"Opt. Laser Technol."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"17764","DOI":"10.1364\/OE.18.017764","article-title":"All-optical signal processing at ultra-low powers in bottle microresonators using the Kerr effect","volume":"18","author":"Pollinger","year":"2010","journal-title":"Opt. Express"},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"1155","DOI":"10.1002\/adom.201400322","article-title":"Direct Sensing in Liquids Using Whispering-Gallery-Mode Droplet Resonators","volume":"2","author":"Avino","year":"2014","journal-title":"Adv. Opt. Mater."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"3863","DOI":"10.1002\/smll.201400813","article-title":"Large-Scale Parallel Surface Functionalization of Goblet-type Whispering Gallery Mode Microcavity Arrays for Biosensing Applications","volume":"10","author":"Bog","year":"2014","journal-title":"Small"},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"3826","DOI":"10.1364\/OL.40.003826","article-title":"Vertical optical ring resonators fully integrated with nanophotonic waveguides on silicon-oninsulator substrates","volume":"40","author":"Madani","year":"2015","journal-title":"Opt. Lett."},{"key":"ref_47","doi-asserted-by":"crossref","unstructured":"Wang, P.F., Ward, J., Yang, Y., Feng, X., Brambilla, G., Farrell, G., and Chormaic, S.N. (2015). Lead-silicate glass optical microbubble resonator. Appl. Phys. Lett., 106.","DOI":"10.1063\/1.4908054"},{"key":"ref_48","doi-asserted-by":"crossref","unstructured":"Lutti, J., Langbein, W., and Borri, P. (2008). A monolithic optical sensor based on whispering-gallery modes in polystyrene microspheres. Appl. Phys. Lett., 93.","DOI":"10.1063\/1.2998652"},{"key":"ref_49","doi-asserted-by":"crossref","unstructured":"Francois, A., and Himmelhaus, M. (2008). Optical biosensor based on whispering gallery mode excitations in clusters of microparticles. Appl. Phys. Lett., 92.","DOI":"10.1063\/1.2907491"},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"45","DOI":"10.1038\/385045a0","article-title":"Ray and wave chaos in asymmetric resonant optical cavities","volume":"385","author":"Nockel","year":"1997","journal-title":"Nature"},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"1312","DOI":"10.1364\/JOSAB.25.001312","article-title":"Optical resonances in microcylinders: Response to perturbations for biosensing","volume":"25","author":"Chantada","year":"2008","journal-title":"J. Opt. Soc. Am. B Opt. Phys."},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"270","DOI":"10.1109\/LPT.2011.2177518","article-title":"Vertically Coupled Polymer Microracetrack Resonators for Label-Free Biochemical Sensors","volume":"24","author":"Delezoide","year":"2012","journal-title":"IEEE Photonics Technol. Lett."},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"4320","DOI":"10.1364\/OL.38.004320","article-title":"Whispering gallery mode diamond resonator","volume":"38","author":"Ilchenko","year":"2013","journal-title":"Opt. Lett."},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"166","DOI":"10.1364\/OL.32.000166","article-title":"Ultralow-threshold Raman lasing with CaF2 resonators","volume":"32","author":"Grudinin","year":"2007","journal-title":"Opt. Lett."},{"key":"ref_55","doi-asserted-by":"crossref","first-page":"139","DOI":"10.1007\/978-1-60327-567-5_7","article-title":"Label-free detection with the liquid core optical ring resonator sensing platform","volume":"503","author":"White","year":"2009","journal-title":"Methods Mol. Biol."},{"key":"ref_56","doi-asserted-by":"crossref","first-page":"92","DOI":"10.1364\/OL.31.000092","article-title":"White-light whispering gallery mode resonators","volume":"31","author":"Savchenkov","year":"2006","journal-title":"Opt. Lett."},{"key":"ref_57","doi-asserted-by":"crossref","unstructured":"Rosenblum, S., Lovsky, Y., Arazi, L., Vollmer, F., and Dayan, B. (2015). Cavity ring-up spectroscopy for ultrafast sensing with optical microresonators. Nat. Commun., 6.","DOI":"10.1038\/ncomms7788"},{"key":"ref_58","doi-asserted-by":"crossref","first-page":"69","DOI":"10.1021\/ac902451b","article-title":"Quantitative, label-free detection of five protein biomarkers using multiplexed arrays of silicon photonic microring resonators","volume":"82","author":"Washburn","year":"2010","journal-title":"Anal. Chem."},{"key":"ref_59","doi-asserted-by":"crossref","first-page":"818","DOI":"10.1016\/j.cbpa.2013.06.014","article-title":"Biomolecular analysis with microring resonators: Applications in multiplexed diagnostics and interaction screening","volume":"17","author":"Kindt","year":"2013","journal-title":"Curr. Opin. Chem. Biol."},{"key":"ref_60","doi-asserted-by":"crossref","first-page":"793","DOI":"10.1021\/ac2029024","article-title":"High-Q Optical Sensors for Chemical and Biological Analysis","volume":"84","author":"Luchansky","year":"2011","journal-title":"Anal. Chem."},{"key":"ref_61","doi-asserted-by":"crossref","first-page":"41501","DOI":"10.1063\/1.4816934","article-title":"Protein immobilization techniques for microfluidic assays","volume":"7","author":"Kim","year":"2013","journal-title":"Biomicrofluidics"},{"key":"ref_62","doi-asserted-by":"crossref","first-page":"041104","DOI":"10.1063\/1.4789755","article-title":"Fine-tuning of whispering gallery modes in on-chip silica microdisk resonators within a full spectral range","volume":"102","author":"Henze","year":"2013","journal-title":"Appl. Phys. Lett."},{"key":"ref_63","doi-asserted-by":"crossref","first-page":"33","DOI":"10.1016\/j.optcom.2006.03.028","article-title":"Ultra high Q crystalline microcavities","volume":"265","author":"Grudinin","year":"2006","journal-title":"Opt. Commun."},{"key":"ref_64","doi-asserted-by":"crossref","first-page":"097006","DOI":"10.1117\/1.JBO.19.9.097006","article-title":"Photonic detection and characterization of DNA using sapphire microspheres","volume":"19","author":"Murib","year":"2014","journal-title":"J. Biomed. Opt."},{"key":"ref_65","doi-asserted-by":"crossref","first-page":"118","DOI":"10.3390\/bios5010118","article-title":"Whispering gallery mode resonators for rapid label-free biosensing in small volume droplets","volume":"5","author":"Wildgen","year":"2015","journal-title":"Biosensors"},{"key":"ref_66","doi-asserted-by":"crossref","first-page":"668","DOI":"10.1038\/nmat1225","article-title":"Diamond films\u2014Precious biosensors","volume":"3","author":"Carlisle","year":"2004","journal-title":"Nat. Mater."},{"key":"ref_67","doi-asserted-by":"crossref","first-page":"091114","DOI":"10.1063\/1.1873043","article-title":"Erbium-doped and Raman microlasers on a silicon chip fabricated by the sol-gel process","volume":"86","author":"Yang","year":"2005","journal-title":"Appl. Phys. Lett."},{"key":"ref_68","doi-asserted-by":"crossref","first-page":"1974","DOI":"10.1007\/s10439-009-9713-2","article-title":"Whispering Gallery Mode Biosensors Consisting of Quantum Dot-Embedded Microspheres","volume":"37","author":"Beier","year":"2009","journal-title":"Ann. Biomed. Eng."},{"key":"ref_69","doi-asserted-by":"crossref","first-page":"043902","DOI":"10.1103\/PhysRevLett.91.043902","article-title":"Ideality in a fiber-taper-coupled microresonator system for application to cavity quantum electrodynamics","volume":"91","author":"Spillane","year":"2003","journal-title":"Phys. Rev. Lett."},{"key":"ref_70","doi-asserted-by":"crossref","first-page":"1129","DOI":"10.1364\/OL.22.001129","article-title":"Phase-matched excitation of whispering-gallery-mode resonances by a fiber taper","volume":"22","author":"Knight","year":"1997","journal-title":"Opt. Lett."},{"key":"ref_71","doi-asserted-by":"crossref","first-page":"147","DOI":"10.1364\/JOSAB.16.000147","article-title":"Optical microsphere resonators: Optimal coupling to high-Q whispering-gallery modes","volume":"16","author":"Gorodetsky","year":"1999","journal-title":"J. Opt. Soc. Am. B Opt. Phys."},{"key":"ref_72","doi-asserted-by":"crossref","first-page":"704","DOI":"10.1109\/50.754802","article-title":"Analytic theory of coupling from tapered fibers and half-blocks into microsphere resonators","volume":"17","author":"Little","year":"1999","journal-title":"J. Lightwave Technol."},{"key":"ref_73","doi-asserted-by":"crossref","first-page":"723","DOI":"10.1364\/OL.24.000723","article-title":"Pigtailing the high-Q microsphere cavity: A simple fiber coupler for optical whispering-gallery modes","volume":"24","author":"Ilchenko","year":"1999","journal-title":"Opt. Lett."},{"key":"ref_74","doi-asserted-by":"crossref","first-page":"1467","DOI":"10.1364\/JOSA.61.001467","article-title":"Optimum Excitation of Optical Surface Waves","volume":"61","author":"Ulrich","year":"1971","journal-title":"J. Opt. Soc. Am."},{"key":"ref_75","unstructured":"Nussenzveig, H.M. (2006). Diffraction Effects in Semiclassical Scattering, Cambridge University Press. [1st pbk. ed.]."},{"key":"ref_76","doi-asserted-by":"crossref","first-page":"343","DOI":"10.1364\/JOSAA.10.000343","article-title":"Theory of morphology-dependent resonances: Shape resonances and width formulas","volume":"10","author":"Johnson","year":"1993","journal-title":"J. Opt. Soc. Am. A"},{"key":"ref_77","doi-asserted-by":"crossref","first-page":"247","DOI":"10.1364\/OL.23.000247","article-title":"High-Q measurements of fused-silica microspheres in the near infrared","volume":"23","author":"Vernooy","year":"1998","journal-title":"Opt. Lett."},{"key":"ref_78","unstructured":"Vollmer, F. (2004). Resonant Detection of Nano to Microscopic Objects Using Whispering Gallery Modes. [Ph.D. Thesis, Rockefeller University]."},{"key":"ref_79","doi-asserted-by":"crossref","first-page":"256","DOI":"10.1364\/OL.26.000256","article-title":"Microtorus: A high-finesse microcavity with whispering-gallery modes","volume":"26","author":"Ilchenko","year":"2001","journal-title":"Opt. Lett."},{"key":"ref_80","doi-asserted-by":"crossref","first-page":"1209","DOI":"10.1109\/TMTT.2007.897850","article-title":"Traceable 2-D finite-element simulation of the whispering-gallery modes of axisymmetric electromagnetic resonators","volume":"55","author":"Oxborrow","year":"2007","journal-title":"IEEE Trans. Microw. Theory Tech."},{"key":"ref_81","doi-asserted-by":"crossref","unstructured":"Vahala, K. (2004). Optical Microcavities, World Scientific.","DOI":"10.1142\/9789812565730"},{"key":"ref_82","unstructured":"Schwinger, J., and Radiation Laboratory, Massachusetts Institute of Technology (1943). The Theory of Obstacles in Resonant Cavities and Wave Guides, Radiation Laboratory, Massachusetts Institute of Technology."},{"key":"ref_83","doi-asserted-by":"crossref","first-page":"428","DOI":"10.1038\/nnano.2011.99","article-title":"Detecting single viruses and nanoparticles using whispering gallery microlasers","volume":"6","author":"He","year":"2011","journal-title":"Nat. Nano"},{"key":"ref_84","doi-asserted-by":"crossref","first-page":"46","DOI":"10.1038\/nphoton.2009.237","article-title":"On-chip single nanoparticle detection and sizing by mode splitting in an ultrahigh-Q microresonator","volume":"4","author":"Zhu","year":"2010","journal-title":"Nat. Photonics"},{"key":"ref_85","doi-asserted-by":"crossref","first-page":"027406","DOI":"10.1103\/PhysRevLett.103.027406","article-title":"Purcell-Factor-Enhanced Scattering from Si Nanocrystals in an Optical Microcavity","volume":"103","author":"Kippenberg","year":"2009","journal-title":"Phys. Rev. Lett."},{"key":"ref_86","doi-asserted-by":"crossref","first-page":"071111","DOI":"10.1063\/1.3481352","article-title":"Demonstration of mode splitting in an optical microcavity in aqueous environment","volume":"97","author":"Kim","year":"2010","journal-title":"Appl. Phys. Lett."},{"key":"ref_87","doi-asserted-by":"crossref","first-page":"5616","DOI":"10.1002\/adma201302572","article-title":"Detection of Single Nanoparticles and Lentiviruses Using Microcavity Resonance Broadening","volume":"25","author":"Shao","year":"2013","journal-title":"Adv. Mater."},{"key":"ref_88","doi-asserted-by":"crossref","unstructured":"Yu, W.Y., Jiang, W.C., Lin, Q., and Lu, T. (2016). Cavity optomechanical spring sensing of single molecules. Nat. Commun., 7.","DOI":"10.1038\/ncomms12311"},{"key":"ref_89","doi-asserted-by":"crossref","first-page":"e110","DOI":"10.1038\/lsa.2013.66","article-title":"Cavity optomechanics on a microfluidic resonator with water and viscous liquids","volume":"2","author":"Kim","year":"2013","journal-title":"Light Sci. Appl."},{"key":"ref_90","first-page":"E3836","article-title":"Highly sensitive detection of nanoparticles with a self-referenced and self-heterodyned whispering-gallery Raman microlaser","volume":"111","author":"Zhu","year":"2014","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_91","doi-asserted-by":"crossref","first-page":"14657","DOI":"10.1073\/pnas.1408453111","article-title":"Single nanoparticle detection using split-mode microcavity Raman lasers","volume":"111","author":"Li","year":"2014","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_92","doi-asserted-by":"crossref","first-page":"600","DOI":"10.1126\/science.aah6516","article-title":"Microresonator soliton dual-comb spectroscopy","volume":"354","author":"Suh","year":"2016","journal-title":"Science"},{"key":"ref_93","doi-asserted-by":"crossref","first-page":"14694","DOI":"10.1364\/OE.17.014694","article-title":"High-Q polymer-coated microspheres for immunosensing applications","volume":"17","author":"Soria","year":"2009","journal-title":"Opt. Express"},{"key":"ref_94","doi-asserted-by":"crossref","first-page":"379","DOI":"10.1038\/nnano.2012.51","article-title":"Optical detection of single non-absorbing molecules using the surface plasmon resonance of a gold nanorod","volume":"7","author":"Zijlstra","year":"2012","journal-title":"Nat. Nanotechnol."},{"key":"ref_95","doi-asserted-by":"crossref","first-page":"733","DOI":"10.1038\/nphoton.2016.177","article-title":"Optical observation of single atomic ions interacting with plasmonic nanorods in aqueous solution","volume":"10","author":"Baaske","year":"2016","journal-title":"Nat. Photonics"},{"key":"ref_96","doi-asserted-by":"crossref","first-page":"14169","DOI":"10.1364\/OE.21.014169","article-title":"Finite element simulation of a perturbed axial-symmetric whispering-gallery mode and its use for intensity enhancement with a nanoparticle coupled to a microtoroid","volume":"21","author":"Kaplan","year":"2013","journal-title":"Opt. Express"},{"key":"ref_97","doi-asserted-by":"crossref","first-page":"183106","DOI":"10.1063\/1.4804243","article-title":"Detection of nanoparticles with a frequency locked whispering gallery mode microresonator","volume":"102","author":"Swaim","year":"2013","journal-title":"Appl. Phys. Lett."},{"key":"ref_98","doi-asserted-by":"crossref","first-page":"788","DOI":"10.1038\/nphoton.2016.217","article-title":"Optical microresonators as single-particle absorption spectrometers","volume":"10","author":"Heylman","year":"2016","journal-title":"Nat. Photonics"},{"key":"ref_99","doi-asserted-by":"crossref","first-page":"6230","DOI":"10.1364\/OE.17.006230","article-title":"Whispering gallery mode carousel\u2014A photonic mechanism for enhanced nanoparticle detection in biosensing","volume":"17","author":"Arnold","year":"2009","journal-title":"Opt. Express"},{"key":"ref_100","doi-asserted-by":"crossref","first-page":"63","DOI":"10.1049\/el:20040062","article-title":"Integrated optics ring-resonator chemical sensor with polymer transduction layer","volume":"40","author":"Ksendzov","year":"2004","journal-title":"Electron. Lett."},{"key":"ref_101","doi-asserted-by":"crossref","first-page":"969","DOI":"10.1364\/OL.39.000969","article-title":"Trace gas absorption spectroscopy using functionalized microring resonators","volume":"39","author":"Stievater","year":"2014","journal-title":"Opt. Lett."},{"key":"ref_102","doi-asserted-by":"crossref","first-page":"10254","DOI":"10.1364\/OE.16.010254","article-title":"Analysis of ring resonators for chemical vapor sensor development","volume":"16","author":"Sun","year":"2008","journal-title":"Opt. Express"},{"key":"ref_103","doi-asserted-by":"crossref","unstructured":"Cho, S.Y., Dobbs, G., Jokerst, N.M., Mizaikoff, B., and Cooper, T. (2007, January 6\u201311). Optical Microring Resonator Sensors with Selective Membrane Surface Customization. Proceedings of the 2007 Conference on Lasers & Electro-Optics\/Quantum Electronics and Laser Science Conference (CLEO\/QELS 2007), Baltimore, MD, USA.","DOI":"10.1109\/CLEO.2007.4453152"},{"key":"ref_104","doi-asserted-by":"crossref","first-page":"1426","DOI":"10.1021\/acs.analchem.5b04187","article-title":"Integrating Whispering Gallery Mode Refractive Index Sensing with Capillary Electrophoresis Separations Using Phase Sensitive Detection","volume":"88","author":"Kim","year":"2016","journal-title":"Anal. Chem."},{"key":"ref_105","doi-asserted-by":"crossref","first-page":"6463","DOI":"10.1364\/AO.49.006463","article-title":"Ultrasensitive chemical sensors based on whispering gallery modes in a microsphere coated with zeolite","volume":"49","author":"Lin","year":"2010","journal-title":"Appl. Opt."},{"key":"ref_106","doi-asserted-by":"crossref","first-page":"1270","DOI":"10.1364\/OL.30.001270","article-title":"Synthesis of MFI zeolite films on optical fibers for detection of chemical vapors","volume":"30","author":"Xiao","year":"2005","journal-title":"Opt. Lett."},{"key":"ref_107","doi-asserted-by":"crossref","first-page":"11855","DOI":"10.1364\/OE.20.011855","article-title":"Selective and reversible ammonia gas detection with nanoporous film functionalized silicon photonic micro-ring resonator","volume":"20","author":"Yebo","year":"2012","journal-title":"Opt. Express"},{"key":"ref_108","doi-asserted-by":"crossref","first-page":"6788","DOI":"10.3390\/s100706788","article-title":"A Microring Resonator Sensor for Sensitive Detection of 1,3,5-Trinitrotoluene (TNT)","volume":"10","author":"Orghici","year":"2010","journal-title":"Sensors"},{"key":"ref_109","doi-asserted-by":"crossref","first-page":"10653","DOI":"10.1021\/ac402972d","article-title":"Subpicogram per milliliter detection of interleukins using silicon photonic microring resonators and an enzymatic signal enhancement strategy","volume":"85","author":"Kindt","year":"2013","journal-title":"Anal. Chem."},{"key":"ref_110","doi-asserted-by":"crossref","first-page":"5578","DOI":"10.1021\/ac060473+","article-title":"Theoretical and experimental analysis of arrayed imaging reflectometry as a sensitive proteomics technique","volume":"78","author":"Mace","year":"2006","journal-title":"Anal. Chem."},{"key":"ref_111","doi-asserted-by":"crossref","first-page":"1458","DOI":"10.1109\/LPT.2013.2266573","article-title":"Encapsulation of a Fiber Taper Coupled Microtoroid Resonator in a Polymer Matrix","volume":"25","author":"Monifi","year":"2013","journal-title":"IEEE Photonics Technol. Lett."},{"key":"ref_112","doi-asserted-by":"crossref","first-page":"2945","DOI":"10.1002\/adma.201504976","article-title":"Chip-Scale Fabrication of High-Q All-Glass Toroidal Microresonators for Single-Particle Label-Free Imaging","volume":"28","author":"Knapper","year":"2016","journal-title":"Adv. Mater."},{"key":"ref_113","doi-asserted-by":"crossref","first-page":"9282","DOI":"10.1039\/C5NR01780G","article-title":"Nanoparticle-coated micro-optofluidic ring resonator as a detector for microscale gas chromatographic vapor analysis","volume":"7","author":"Scholten","year":"2015","journal-title":"Nanoscale"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/17\/3\/540\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T18:30:01Z","timestamp":1760207401000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/17\/3\/540"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2017,3,8]]},"references-count":113,"journal-issue":{"issue":"3","published-online":{"date-parts":[[2017,3]]}},"alternative-id":["s17030540"],"URL":"https:\/\/doi.org\/10.3390\/s17030540","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2017,3,8]]}}}