A novel microsensor for measuring thermal conductivity of fluid based on three omega method.

A novel microsensor has been designed for the measurement of thermal conductivity of fluids based on the three omega (3ω) method. First, we theoretically analyzed the heat conduction using the 3ω method to demonstrate the mechanism of the microsensor to measure the thermal conductivity of a fluid. For the main structure of the microsensor, a heater was supported by the thin dielectric layers. In order to obtain the optimal parameters, we used the finite element method to simulate the working condition of the microsensor. In the simulation model, the effects of the thicknesses of the heater and dielectric layers on the thermal conductivity λ of the fluid were analyzed. The simulation results confirmed the validity and accuracy of conventional analytical calculations. Based on the simulation and theoretical calculation, a microsensor was optimally designed and fabricated to measure the thermal conductivity of fluids. Experimental data are consistent with those reported in the literature and demonstrate that the proposed sensor is effective for measuring thermal conductivity of fluids, including conductive ones.