A Thick Film Capacitive Temperature Sensor Using Barium Strontium Titanate Glass Formulations

Abstract

This paper describes a novel use of thick film techniques to produce a temperature sensor. Ferroelectric materials above their Curie temperature exhibit a dielectric constant which is inversely dependent upon temperature. The measuring range of the sensor can be altered by varying the ratio of the ferroelectric components used (BaTiO3and SrTiO3). By using this ceramic together with a glass frit to form a paste, it is possible to employ standard thick film techniques to produce the sensors. Sensors with a composition (Ba0.5Sr0.5)TiO3were subjected to various temperature and ambient conditions to investigate their temperature performance and stability. The sensors were fundamentally stable and exhibited a capacitance change as large as 65% of their initial value over a temperature range of 100℃ and yet the dependence was linear to within 1.5℃.