Visualization of Temperature Distribution in Microchannel Using 2-Color Laser-induced Fluorescence

This paper presents a novel temperature measurement method for microfluidic devices; “2-Color Laser-induced Fluorescence (2-Color LIF)”. In general, a conventional method (1-Color LIF) strongly depends on the excitation intensity distribution which is generated by spatio-temporal intensity fluctuation of light itself and configuration of microchannel. In contrast, the proposed method can eliminate the undesirable influence using a ratio-metric technique with two fluorescence images, because fluorescence intensity can be approximately a linear function of the excitation light intensity. Therefore, it is possible to measure the temperature distribution quantitatively and simplify temperature calibration. In this experiment, this was applied to calibrate between the temperature and normalized ratio value which dividing the Rhodamine B fluorescence image with Rhodamine 110 fluorescence image in microchannel. As a result, spatial intensity error can be reduced to about 95% as compared with 1-Color LIF image. The temperature distribution in microchannel due to heat-diffusion was visualized with high resolution 0.24μm×0.24μm and sensitivity 1.48%/K.