Development of oxide thick film capacitors for a real time pressure monitoring system

Accurate pressure readings are essential tools in a wide range of applications. For example in monitoring intracranial pressure for patients with head injuries or tyre pressure to improve automobile safety. With this in mind, a real time monitoring system, which displays the change in sensor capacitance with pressure on a PC, has been developed. Thick film capacitors with an oxide dielectric layer formed using niobium pentoxide (Nb 2 O 5 ), titanium dioxide (TiO 2 ) and cerium dioxide (CeO 2 ) are investigated using this system. SEM was used to examine the morphology and particle size of the thick films. To aid in the development of a suitable interface circuitry, the frequency and temperature dependence of each device is investigated. Each sensor was then subjected to pressures in the region of 0–100 kPa. The results show that capacitors with an Nb 2 O 5 dielectric layer were most sensitive. It is thought that this is due to its particle size.