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Optics Express
|June 25, 2009
Summary
This study presents a theory for how bacteria on micro-optical resonators cause frequency shifts and linewidth broadening. Measurements with E.Coli confirm the whispering gallery mode (WGM) biosensor
Area of Science:
- Optics and Photonics
- Biophysics
- Biosensing Technology
Background:
- Micro-optical resonators are sensitive to their environment.
- Biological analytes can alter resonator properties.
- Whispering gallery modes (WGMs) are susceptible to surface binding events.
Purpose of the Study:
- To develop a theoretical model for optical shifts and linewidth broadening in micro-optical resonators caused by bound rodlike bacteria.
- To quantify the sensitivity of WGM biosensors for microorganism detection.
- To validate theoretical predictions with experimental measurements.
Main Methods:
- Theoretical modeling of frequency shift using a form factor for random bacterial orientation.
- Estimation of linewidth broadening from scattering losses.
- Experimental validation using E.Coli bacteria and micro-optical resonators.
Main Results:
- A theoretical framework was established for optical shifts and linewidth broadening induced by bacteria.
- The model accurately accounts for the influence of bacterial orientation and refractive index.
- Experimental results confirmed the theoretical predictions with high sensitivity (~10^2 bacteria/mm^2).
Conclusions:
- Whispering gallery mode (WGM) biosensors offer a sensitive technique for detecting and analyzing microorganisms.
- The developed theory provides a basis for understanding and optimizing WGM biosensor performance.
- This approach has potential applications in microbial detection and diagnostics.
