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Analysis of an optical biosensor based on elastic light scattering from diamond‐, glass‐, and sapphire microspheres
Author(s) -
Murib Mohammed S.,
Tran Anh Quang,
De Ceuninck Ward,
Schöning Michael J.,
Nesládek Milos,
Serpengüzel Ali,
Wagner Patrick
Publication year - 2012
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201100795
Subject(s) - refractive index , whispering gallery wave , materials science , biosensor , diamond , optics , glass microsphere , biomolecule , sapphire , wavelength , total internal reflection , refractive index contrast , radius , resonator , optoelectronics , nanotechnology , microsphere , laser , fabrication , physics , composite material , medicine , alternative medicine , engineering , pathology , computer security , chemical engineering , computer science
Abstract Deoxyribonucleic acid (DNA) and protein recognition are now standard tools in biology. In addition, the special optical properties of microsphere resonators expressed by the high quality factor ( Q ‐factor) of whispering gallery modes (WGMs) or morphology dependent resonances (MDRs) have attracted the attention of the biophotonic community. Microsphere‐based biosensors are considered as powerful candidates to achieve label‐free recognition of single molecules due to the high sensitivity of their WGMs. When the microsphere surface is modified with biomolecules, the effective refractive index and the effective size of the microsphere change resulting in a resonant wavelength shift. The transverse electric (TE) and the transverse magnetic (TM) elastic light scattering intensity of electromagnetic waves at 600 and 1400 nm are numerically calculated for DNA and unspecific binding of proteins to the microsphere surface. The effect of changing the optical properties was studied for diamond (refractive index 2.34), glass (refractive index 1.50), and sapphire (refractive index 1.75) microspheres with a 50 µm radius. The mode spacing, the linewidth of WGMs, and the shift of resonant wavelength due to the change in radius and refractive index, were analyzed by numerical simulations. Preliminary results of unspecific binding of biomolecules are presented. The calculated shift in WGMs can be used for biomolecules detection.