Evanescent field-based optical fiber sensing device for measuring the refractive index of liquids in microfluidic channels

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283 Scopus citations

Abstract

We report a simple optical sensing device capable of measuring the refractive index of liquids propagating in microfluidic channels. The sensor is based on a single-mode optical fiber that is tapered to submicrometer dimensions and immersed in a transparent curable soft polymer. A channel for liquid analyte is created in the immediate vicinity of the taper waist. Light propagating through the tapered section of the fiber extends into the channel, making the optical loss in the system sensitive to the refractive-index difference between the polymer and the liquid. The fabrication process and testing of the prototype sensing devices are described. The sensor can operate both as a highly responsive on-off device and in the continuous measurement mode, with an estimated accuracy of refractive-index measurement of ∼5×10-4.

Original languageEnglish (US)
Pages (from-to)1273-1275
Number of pages3
JournalOptics letters
Volume30
Issue number11
DOIs
StatePublished - Jun 1 2005

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

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