title: Plasmonic Mach-Zehnder interferometer for ultrasensitive on-chip biosensing.
abstract: We experimentally demonstrate a plasmonic Mach-Zehnder interferometer (MZI) integrated with a microfluidic chip for ultrasensitive optical biosensing. The MZI is formed by patterning two parallel nanoslits in a thin metal film, and the sensor monitors the phase difference, induced by surface biomolecular adsorptions, between surface plasmon waves propagating on top and bottom surfaces of the metal film. The combination of a nanoplasmonic architecture and sensitive interferometric techniques in this compact sensing platform yields enhanced refractive index sensitivities greater than 3500 nm/RIU and record high sensing figures of merit exceeding 200 in the visible region, greatly surpassing those of previous plasmonic sensors and still hold potential for further improvement through optimization of the device structure. We demonstrate real-time, label-free, quantitative monitoring of streptavidin-biotin specific binding with high signal-to-noise ratio in this simple, ultrasensitive, and miniaturized plasmonic biosensor.
authors: Center for Optical Technologies, Electrical and Computer Engineering Department, Lehigh University, Bethlehem, Pennsylvania 18015, United States.
authors: Yongkang
authors: Y
authors: Gao
authors: Qiaoqiang
authors: Q
authors: Gan
authors: Zheming
authors: Z
authors: Xin
authors: Xuanhong
authors: X
authors: Cheng
authors: Filbert J
authors: FJ
authors: Bartoli
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007118:Immunoassay / Q000295:instrumentation*; D007368:Interferometry / Q000295:instrumentation*; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*; D036103:Nanotechnology / Q000295:instrumentation*; D020349:Surface Plasmon Resonance / Q000295:instrumentation*