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Stand-off biodetection with free-space coupled asymmetric microsphere cavities
Zachary Ballard1, Martin D Baaske2, Frank Vollmer3
1Max Planck Institute for the Science of Light, Laboratory of Nanophotonics & Biosensing, Guenther-Scharowsky-Str. 1/Bldg. 24, Erlangen D-91058, Germany. zachscottballard@gmail.com.
Sensors (Basel, Switzerland)
|April 21, 2015
Summary
Asymmetric microsphere resonators enable "stand-off" biodetection by allowing researchers to measure whispering gallery modes (WGMs) from a distance. This optical fiber-based approach facilitates sensitive protein adsorption detection in aqueous solutions.
Area of Science:
- Optics and Photonics
- Biotechnology
- Materials Science
Background:
- Asymmetric microsphere resonators (ARCs) offer unique optical properties for sensing applications.
- Whispering gallery modes (WGMs) are sensitive to changes in the resonator's environment.
- Traditional WGM sensing often requires near-field coupling, limiting practical applications.
Purpose of the Study:
- To demonstrate free-space coupling to high-Q WGMs in ARCs fabricated from optical fibers.
- To enable non-contact, "stand-off" WGM resonance measurements.
- To detect biomolecular interactions in aqueous solutions using this novel approach.
Main Methods:
- Fabrication of asymmetric microsphere resonators from optical fibers.
- Excitation of high-Q WGMs via dynamical tunneling.
- Characterization of directional light emission using fluorescence imaging.
- Demonstration of free-space coupling in an aqueous environment.
- Monitoring protein adsorption kinetics.
Main Results:
- Successful excitation of high-Q WGMs in fiber-based ARCs.
- Demonstration of efficient free-space coupling to WGMs in aqueous media.
- Observation of coupled mode effects through dynamical tunneling.
- Quantification of protein adsorption kinetics on the resonator surface.
Conclusions:
- ARCs provide a robust platform for far-field WGM sensing.
- The developed method allows for non-invasive, stand-off biodetection.
- This technology paves the way for advanced microfluidic and in-vivo WGM biosensing platforms.
