Development of pressure sensors by powder technology

Thick film deposition of conductive, dielectric and resistive pastes on ceramic membranes is a cost effective technique to manufacture piezoresistive pressure sensors. Thick-film resistors consist of a percolating network of conductive oxide nanoparticles dispersed in an insulating glassy matrix, the electrical properties of which depend on firing conditions and composition. Ceramic membranes are appropriate to withstand the firing temperatures of thick-film materials, which are about 850°C. However brittleness is a common drawback for high performance applications. In this work, the feasibility of producing piezoresistive films on metallic substrates is investigated. Two routes are explored: a) thick-film deposition of novel materials with low firing temperature on standard steels substrates, and b) standard thick-film deposition on special alloys, which do not undergo mechanical degradation at 850°C. The metallic substrates are manufactured by metal injection molding, or by cold compaction of powder blends followed by natural sintering. The mechanical and electrical properties of the novel sensors are evaluated.