Sensitive optofluidic flow rate sensor based on laser heating and microring resonator

Abstract

We demonstrate an optofluidic flow rate sensor based on the heat transfer effect in a microfluidic channel for the lab-on-a-chip applications. By employing an optofluidic ring resonator (OFRR), the wavelength shift of the resonant dip of the whispering gallery mode is detected as a function of the flow rate when the flow is heated by a 1480-nm laser. A measurement range of 2–100 μL/min, a minimum detectable change of 30 nL/min, and an accuracy of 5.2 % for the flow rate detection are achieved. Experimental results indicate that the OFRR flow rate sensor has good repeatability, and the inverse sensitivity is beneficial for detecting the low flow rate with high sensitivity.