Optical characterization of the heating performance of microchannel fluid flow

The temperature dependent quantum efficiency of fluorescent dyes can be used to measure changes in temperature of the fluorescent dye molecules. This paper describes the use of Rhodamine dye as a temperature sensitive based fluorescence indicator for the characterization of heating in a pressure driven microfluidic device with high spatial resolution. A microheating element is used to control the temperature of the fluid in order to create localized heating in the microchannel. The temperature dependent fluorescence intensity of Rhodamine 6G for a concentration of 1mmol/L is characterized with a 5th order polynomial then used to detect the temperature of the fluid in a microchannel. Fluid temperatures in the range of 2020–85°C are measured with an uncertainty of <2°C using a confocal fluorescence microscope. This method enables the characterization, imaging and mapping of three-dimensional temperature gradients within a microchannel.