Label-free optical biosensing using a horizontal air-slot SiNx microdisk resonator

We demonstrate label-free optical biosensing using a horizontal air-slotted silicon-rich silicon nitride (SiNx) microdisk resonator. Due to the strong confinement of light in the air-slot, a large resonance shift of 6.2 nm is observed upon reaction of the biotin-functionalized disk with a streptavid...

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Bibliographic Details
Published in:Optics express 2010-09, Vol.18 (20), p.20638-20644
Main Authors: Lee, Shinyoung, Eom, Seok Chan, Chang, Jee Soo, Huh, Chul, Sung, Gun Yong, Shin, Jung H
Format: Article
Language:English
Subjects:
Biosensing Techniques
Biotin - chemistry
Equipment Design
Hydrogen-Ion Concentration
Microscopy, Electron, Scanning - methods
Models, Statistical
Normal Distribution
Optics and Photonics
Refractometry - methods
Sensitivity and Specificity
Silicon Compounds - chemistry
Staining and Labeling
Streptavidin - chemistry
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Summary:We demonstrate label-free optical biosensing using a horizontal air-slotted silicon-rich silicon nitride (SiNx) microdisk resonator. Due to the strong confinement of light in the air-slot, a large resonance shift of 6.2 nm is observed upon reaction of the biotin-functionalized disk with a streptavidin solution with concentration of 2.5 μg/ml. Assuming a linear relationship between resonance shift and streptavidin concentration, we estimate the sensitivity to be 2.5 ± 0.2 nm/(μg/ml). Comparing this value with surface sensitivity of 5.7 nm/nm calculated using FDTD simulations, a detection limit of 30 ± 2 ng/ml, is extrapolated.
ISSN:1094-4087
DOI:10.1364/OE.18.020638