Optofluidic Temperature and Pressure Measurements with Fiber Bragg Gratings Embedded in Microfluidic Devices

G.A. Cooksey, J.D. Wright, Z. Ahmed
National Institute of Standards and Technology,
United States

Keywords: optofluidic, microfluidics, temperature, pressure


(INTRODUCTION) The integration of photonic sensors into microfluidic devices provides opportunities for dynamic measurement of chemical and physical properties of fluids in very small volumes. Microfluidic platforms provide sub-microliter control of fluid transport and mixing of chemicals over a broad range of length and time scales. Meanwhile, advances in photonic technology are facilitating new sensing capabilities at the micro- and nanoscale. Fiber Bragg Gratings (FBGs) are highly sensitive to changes in temperature and strain, and their small size and commercial availability make them ideal sensors to embed in microfluidic devices. In this report, we demonstrate the integration of FBGs into easy-to-fabricate microfluidic devices and report on their sensitivity for temperature and pressure measurement in microliter or smaller volumes. (METHODS) These devices are easy to fabricate and assemble with off-the-shelf components. In this study we utilized commercially available FBGs with Bragg resonance in the range of 1540 to 1560 nm (os1100, Micron Optics). Peak resonance was determined after scanning a laser over the resonance region and measuring the power of the reflected signal from embedded fibers (Ahmed et al, 2015). Poly(dimethylsiloxane) (PDMS) membranes were purchased (Interstate Specialty Products) or cured from spun-coat PDMS (Sylgard 184, 10:1 base:crosslinker, Dow Corning). Laser-cut double-sided silicone tape (#96042, 3M™) was used to adhere layers (Cooksey and Atencia, 2014). (RESULTS) A microfluidic channel enabled direct contact of