The Influence of Size Effect on Sensitivity of Cu/CuNi Thin- film Thermocouple

In this paper, the influence of size effect on the sensitivity of Cu/CuNi thin-film thermocouple was studied through experiments and theoretical analysis. Cu/CuNi thin-film thermocouples with different thicknesses of 0.5 μm, 1.0 μm, 1.5 μm and 2.0 μm were fabricated on the substrate with SiO2 lining by means of reactive magnetron sputtering. After static calibration, the sensitivities of the thermocouples were obtained respectively of 46.49 μV/°C, 45.23 μ/°C, 44.56 μV/°C and 43.94 μV/°C. According to the experimental results, it can be seen that the sensitivity of Cu/CuNi thin-film thermocouple is higher than that of the bulk Cu/CuNi thermocouple, and the sensitivity S will increase with the reciprocal of the thickness 1/δ as long as the thickness of the film is greater than the critical value.