Stand-Off Biodetection with Free-Space Coupled Asymmetric Microsphere Cavities

Sensors

Zachary Ballard¹  Martin D. Baaske²  Frank Vollmer¹ 

[1] Max Planck Institute for the Science of Light, Laboratory of Nanophotonics & Biosensing, Guenther-Scharowsky-Str. 1/Bldg. 24, Erlangen D-91058, Germany; E-Mail

关键词: Whispering Gallery Mode (WGM) biosensors;    free-space coupling;    asymmetric resonant cavities;    biosensing;    label-free detection;    protein adsorption;   

DOI  :  10.3390/s150408968

来源: mdpi

【 摘 要 】

Asymmetric microsphere resonant cavities (ARCs) allow for free-space coupling to high quality (Q) whispering gallery modes (WGMs) while exhibiting highly directional light emission, enabling WGM resonance measurements in the far-field. These remarkable characteristics make “stand-off” biodetection in which no coupling device is required in near-field contact with the resonator possible. Here we show asymmetric microsphere resonators fabricated from optical fibers which support dynamical tunneling to excite high-Q WGMs, and demonstrate free-space coupling to modes in an aqueous environment. We characterize the directional emission by fluorescence imaging, demonstrate coupled mode effects due to free space coupling by dynamical tunneling, and detect adsorption kinetics of a protein in aqueous solution. Based on our approach, new, more robust WGM biodetection schemes involving microfluidics and in-vivo measurements can be designed.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.