Plasmonic Mach-Zehnder interferometer for ultrasensitive on-chip biosensing

Yongkang Gao, Qiaoqiang Gan, Zheming Xin, Xuanhong Cheng, Filbert J. Bartoli

Research output: Contribution to journalArticlepeer-review

146 Scopus citations


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. © 2011 American Chemical Society.
Original languageEnglish (US)
Pages (from-to)9836-9844
Number of pages9
JournalACS Nano
Issue number12
StatePublished - Dec 27 2011
Externally publishedYes

ASJC Scopus subject areas

  • General Physics and Astronomy
  • General Materials Science
  • General Engineering


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