An Ultrahigh-Precision Thin-Film Platinum Resistance Sensor for Ocean Temperature Measurements

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This study presents the design and fabrication of an ultrahigh-precision platinum thin-film temperature sensor without an adhesion layer, which effectively eliminates the performance degradation caused by adhesion layer diffusion during high-temperature annealing. A 1-μm-thick platinum film was deposited on an alumina substrate via segmented magnetron sputtering, followed by annealing in air at temperatures ranging from500~∘C to900~∘C. The resistance-temperature relationships of the sensor were characterized over the0~∘C–35~∘C range under various annealing conditions, with a particular focus on the temperature coefficient of resistance (TCR). The morphological and grain size analyses of the platinum film were conducted using X-ray diffraction (XRD) and scanning electron microscopy. Results indicate that optim al sensor performance was achieved with an annealing temperature of800~∘C for 2 h, which leads to an increase in the TCR from2.36 × 10^-3/°C to3.65 × 10^-3/°C. Precision calibration and stability tests show that the sensor achieved an excellent measurement accuracy of0.0019~∘C and a maximum temperature drift of only0.0009~∘C per month over a six-month period. These results indicate that the platinum thin-film sensor exhibits outstanding performance, making it particularly suitable for high-precision ocean temperature measurement applications.