Microscopic Fluid Temperature Measurements Using Fluorescence Polarization Method

A fluid temperature measurement method in microscopic scale using fluorescence polarization is described in this study. The present method has the advantages in not only noncontact but also markedly reducing the influences of solution pH and quenching on the measured fluid temperature, compared to other methods including LIF (laser induced fluorescence) method. In the case of a fluid at rest, the fluorescence intensity varied with pH and linearly decreased with the elapsed time, while the polarization degree remained nearly constant. The polarization degree showed a good correlation with the fluid viscosity and temperature that corresponded to the tendency of the analytical results. The microchannel flows case also showed a good correlation between the fluid temperature and the fluorescence polarization degree was observed, which was similar to the stationary fluid case. These results affirmed the feasibility of our method using fluorescence polarization for fluid temperature measurement.