Different thick-film methods in printing of one-electrode semiconductor gas sensors

Abstract

Different thick-film printing techniques have been used for the fabrication of one-electrode semiconductor gas sensors in the form of thick films on insulating alumina substrate. In a typical one-electrode sensor construction, a thin platinum wire (diameter 20 μm) spiral is embedded inside a sintered oxide semiconductor button. The platinum wire spiral is replaced by a platinum thick-film resistor in our prototype sensor, and the oxide semiconductor is screen printed over the platinum resistor. Both screen printing and gravure off-set printing (pad printing) were used for the printing of platinum thick-film resistors. Tin dioxide, an n-type semiconductor, was used as the sensing (shunting)_thick-film layer over the platinum resistor, and diferent amounts of either silver or antimony were used as additives in SnO 2. H 2S and CO at different concentrations in synthetic air were used to test the response properties of two different sensor types with, respectively, screen-printed and pad-printed platinum thick-film resistors.