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Politecnico Di Bari POLITECNICO DI BARI RESEARCH DOCTORATE IN INFORMATION ENGINEERING XXV CYCLE 2010-2012 SSD: ING-INF/01 DOCTORAL THESIS OPTICAL BIOCHEMICAL PLATFORMS FOR NANOPARTICLES DETECTION Supervisor: Prof. C. CIMINELLI Coordinator of the Ph.D. Course: Prof. B. TURCHIANO Ph.D. Candidate: Clarissa M. CAMPANELLA Per aspera sic itur ad astra. Thanks to all the minds and hearts I met in the past three years And to those pure souls I’ll never forget. LIST OF ABBREVIATIONS: CW Clockwise CCW Counter-Clockwise CMT Coupled Mode Theory ER Extinction Ratio FDTD Finite Difference Time Domain FWHM Full Width at Half Maximum IO Integrated Optics LOD Limit Of Detection NA Numerical Aperture NAIL Numerical Aperture Increasing Lens NP Nanoparticle Q Quality Factor RI Refractive Index RIU Refractive Index Unit SIL Solid Immersion Lens SPR Surface Plasmon Resonance WGM Whispering Gallery Mode TABLE OF CONTENTS Chapter 1 INTRODUCTION ............................................................................................... - 1 - 1.1 DISSERTATION OVERVIEW ................................................................ - 5 - 1.2 REFERENCES .......................................................................................... - 7 - Chapter 2 BIOCHEMICAL SENSORS ................................................................................ - 9 - 2.1 DEFINITION ............................................................................................ - 9 - 2.2 BIO-SENSORS PROPERTIES ............................................................... - 11 - 2.3 SENSITIVE LAYER .............................................................................. - 12 - 2.3.1 RECEPTORS IMMOBILIZATION ON THE SUBSTRATE ......... - 14 - 2.3.2 MOLECULAR RECOGNITION ELEMENTS ............................... - 16 - 2.4 SENSING MECHANISMS AND TRANSDUCING METHODS: OPTICAL DEVICES .................................................................................... - 18 - 2.4.1 ELECTRONIC ABSORPTION SPECTROSCOPY ........................ - 20 - 2.4.2 ELECTRONIC LUMINESCENCE SPECTROSCOPY .................. - 22 - 2.4.3 VIBRATIONAL SPECTROSCOPY ................................................ - 22 - 2.4.4 REFRACTIVE INDEX CHANGE ................................................... - 22 - 2.6 GEOMETRIES OF INTEGRATED OPTICS BIOSENSORS ............... - 25 - 2.6.1 PLANAR WAVEGUIDES ............................................................... - 25 - 2.6.2 PHOTONIC CRYSTAL DEVICES ................................................. - 30 - 2.6.3 FIBER OPTIC BIOSENSORS ......................................................... - 30 - 2.6.4 OPTICAL RESONATORS .............................................................. - 31 - 2.7 CONCLUSIONS ..................................................................................... - 34 - 2.8 REFERENCES ........................................................................................ - 35 - Chapter 3 WHISPERING GALLERY MODE BASED BIO-CHEMICAL SENSORS ......... - 37 - 3.1 OPTICAL RING RESONATOR CONFIGURATIONS AND PERFORMANCES OVERVIEW ................................................................. - 39 - 3.1.1 PLANAR RING RESONATORS .................................................... - 39 - 3.1.2 OPTO-FLUIDIC RING RESONATORS ......................................... - 42 - 3.1.3 MICROSPHERE RING RESONATORS ........................................ - 45 - 3.2 CAVITY DESIGN: DISCUSSION ......................................................... - 51 - 3.2.1 GUIDING STRUCTURE ................................................................. - 51 - 3.2.2 COUPLER SECTION ...................................................................... - 53 - 3.2.2.1.1 RESONATOR-WAVEGUIDE COUPLING ..................... - 59 - 3.2.2.1.2 INTERNAL MODAL COUPLING ................................... - 61 - 3.2.3 LOSS SOURCES .............................................................................. - 65 - 3.2.3.1 INTERNAL LOSS .................................................................... - 65 - 3.2.3.2 BENDING OR RADIATION LOSS ........................................ - 66 - 3.2.3.3 MODAL MISMATCH LOSS ................................................... - 67 - 3.2.4 NOISE SOURCES ............................................................................ - 67 - 3.3 CONCLUSIONS ..................................................................................... - 68 - 3.4 REFERENCES ........................................................................................ - 69 - Chapter 4 NANOPARTICLES DETECTION ..................................................................... - 77 - 4.1 MECHANICAL DETECTION ............................................................... - 79 - 4.2 ELECTRICAL DETECTION ................................................................. - 80 - 4.3 OPTICAL DETECTION ......................................................................... - 81 - 4.3.1 WGM BASED NP DETECTION .................................................... - 81 - 4.3.2 MICROSCOPY BASED NP DETECTION ..................................... - 84 - 4.4 CONCLUSIONS ..................................................................................... - 89 - 4.5 REFERENCES ........................................................................................ - 90 - Chapter 5 WISPERING GALLERY MODEs BASED SINGLE NANOPARTICLE DETECTION ..................................................................................................... - 95 - 5.1 THE HARMONIC OSCILLATOR ......................................................... - 96 - 5.2 NANOPARTICLE SIZING: MATHEMATICAL MODEL .................. - 98 - 5.2.1 DETECTION LIMIT ENHANCEMENT ...................................... - 109 - 5.3 CAVITY DESIGN: HYBRID RING RESONATOR ........................... - 116 - 5.3.1 SINGLE NANOPARTICLE DETECTION AND SIZING ........... - 127 - 5.4 DISCUSSION ....................................................................................... - 134 - 5.4.1 HYBRID RING RESONATORS ADVANTAGES ....................... - 136 - 5.4.2 BIOLOGICAL SENSING: GLUCOSE CONCENTRATION ...... - 138 - 5.4.3 CHALLENGES: ON CHIP PLATFORM ...................................... - 142 - 5.5 CONCLUSIONS ................................................................................... - 144 - 5.6 REFERENCES ...................................................................................... - 145 - Chapter 6 INTERFEROMETRIC REFLECTANCE IMAGING SENSOR BASED NANOPARTICLE DETECTION ..................................................................... - 149 - 6.1 BASICS OF INTERFEROMETRIC MICROSCOPY FOR NANOPARTICLE DETECTION ............................................................... - 150 - 6.2 ANGULAR SPECTRUM REPRESENTATION ................................. - 154 - 6.3 ANGULAR SPECTRUM REPRESENTATION OF A FAR FIELD .. - 156 - 6.4 FIELD FOCUSED BY AN APLANATIC LENS ................................ - 158 - 6.5 FIELD FOCUSED NEAR A PLANAR INTERFACE ......................... - 161 - 6.6 FIELD IN THE IMAGE SPACE .......................................................... - 166 - 6.7 BACK-SIDE ILLUMINATION MODELING ..................................... - 170 - 6.7.1 DIPOLE EXCITATION FIELD ..................................................... - 172 - 6.7.2 DIPOLE SCATTERED FIELD ...................................................... - 173 - 6.7.3 DIPOLE FIELD IN THE IMAGE SPACE .................................... - 174 - 6.7.4 TOTAL FIELD IN THE IMAGE SPACE ..................................... - 175 - 6.8 RESULTS .............................................................................................. - 175 - 6.8.1 DIELECTRIC NPs ......................................................................... - 176 - 6.9 CONCLUSIONS ................................................................................... - 184 - 6.10 REFERENCES .................................................................................... - 185 - Chapter 7 CONCLUSION ................................................................................................ - 187 - 7.1 REFERENCES ...................................................................................... - 190 - APPENDIX 1: RING RESONATORS THEORY .................................................. 191 APPENDIX 2: MICROSCOPY THEORY ............................................................ 198 List of publications Chapter 1. INTRODUCTION Preserving, monitoring, or anyway dealing with the human and environmental health state should be one of the major goals to be pursued in a world always more dominated by a strong correlation between industrial processes and technological advances. Due to their enormous potential, biosensors are widely used for detecting a wide range of analytes in the health care and food industries and in the environmental monitoring. Mainly, the widespread employment of these devices is attributed to the enormous demands of diseases diagnosis and control, as well as to the property of biosensors of offering a convenient, hygienic, rapid, and compact method for personal monitoring [1]. In recent years, indeed, the sensors market has been dominated by an increasing demand in the field of medical diagnostics relying on the individuation of disposable, reliable, user-friendly, cost-efficient devices that also demonstrate fast response times and that are suitable for mass production. All these criteria are potentially fulfilled by biosensor technologies that combine interdisciplinary approaches coming from nanotechnology,
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