Low Cost Thick-Film Pressure Sensor

Pressure sensors in automobiles are used in connexion with electronic systems intended to control carburation. The pressure range to be measured is around the atmospheric pressure, a tolerance in the order of ±2% is required in the temperature range from 0 to 80°C good reproducibility and reliability, especially as for low infant mortality, together with low prices are mandatory.

A new type of pressure sensor aiming to fit the above mentioned characteristics has been developed taking advantage from the piezoresistive effect of thick-film resistors screened-and-fired on ceramic diaphragms.

The device consists of a ceramic diagphram bound around the edge, where in proper positions four resistors electrically connected according to Weathstone bridge configuration are screened-and-fired. The deformation of the diaphragm because of an applied pressure causes bridge unbalancing and output signal proportional to the pressure itself.