An evaluation of materials and processes employed in the construction of novel thick film force sensors

Novel thick film strain gauges have been constructed using a z‐axis orientation on insulated stainless steel for a variety of force sensing applications. These devices exhibit high gauge factor and good thermal stability compared with conventional x‐axis devices and offer other mechanical advantages due to their mode of operation. The work reported here investigates the characteristics of different types of stainless steel substrate and different types of insulating material used in the construction of the sensors. Both ferritic and austenitic steels have been investigated, together with different resistive and insulative compositions. The temperature coefficient of resistance of the devices has been shown to be a complex function of device thickness, surface area and the difference between the thermal coefficients of expansion of the various materials employed.