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 $\sim 5\times {10}^{-4}$.

© 2005 Optical Society of America

Diffraction grating-based sensing optofluidic device for measuring the refractive index of liquids

Sergio Calixto, Neil C. Bruce, and Martha Rosete-Aguilar
Opt. Express 24(1) 180-190 (2016)

Investigation of dual-channel fiber-optic surface plasmon resonance sensing for biological applications

Wei Peng, Soame Banerji, Yoon-Chang Kim, and Karl S. Booksh
Opt. Lett. 30(22) 2988-2990 (2005)

Holey fiber tapers with resonance transmission for high-resolution refractive index sensing

Vladimir P. Minkovich, Joel Villatoro, David Monzón-Hernández, Sergio Calixto, Alexander B. Sotsky, and Ludmila I. Sotskaya
Opt. Express 13(19) 7609-7614 (2005)

Silver halide fiber-based evanescent-wave liquid droplet sensing with room temperature mid-infrared quantum cascade lasers

J. Z. Chen, Z. Liu, C. F. Gmachl, and D. L. Sivco
Opt. Express 13(16) 5953-5960 (2005)

Integrated microfluidic flowmeter based on a micro-FBG inscribed in Co²⁺-doped optical fiber

Zhengyong Liu, Ming-Leung Vincent Tse, A. Ping Zhang, and Hwa-Yaw Tam
Opt. Lett. 39(20) 5877-5880 (2014)