Thick film resistors on alumina substrate as sensing elements

In this paper, thick film resistors (TFRs) on alumina substrate for strain sensor applications have been developed and evaluated. Thick film technology based ceramic pressure sensors (CPS) are fabricated by screen printing and firing four TFRs on a machined circular diaphragm and then the TFRs are connected in a Wheatstone bridge configuration. Finite element method (FEM) is used to optimize structural design and predict the optimal position where the piezoresistive TFRs are placed on the ceramic diaphragm. Preliminary tests show that the sensors exhibit a linearity of 0.4% full-scale (FS), the hysteresis and repeatability are 0.5% FS. Moreover, the thermal zero drifts and thermal sensitivity drifts of the sensors in the whole temperature range (-40 °C to 125 °C) are less than 3% FS. These results indicate that the sensor is a cost-effective choice for many application fields especially in automotive field.