Patent ID: 6861939
Filing Date: 2005-03-01
Classification: G01N

Abstract:
1. A gas sensor for sensing a gas or gas composition at high temperatures, said gas sensor comprising a substrate ( 1 ) having a sensor carrier section with a tip ( 10 ) and a conductor carrier section ( 9 ) connected to said sensor carrier section opposite said tip ( 10 ), said sensor carrier section having zones with varying heat dissipations, a gas sensor function layer ( 4 ) supported by said sensor carrier section of said substrate ( 1 ) next to said tip ( 10 ), an electrical heater ( 6 ) supported by said sensor carrier section in a position for heating said gas sensor function layer ( 4 ), electric power supply conductors ( 2 ) supported on said conductor carrier section ( 9 ) of said substrate ( 1 ) and electrically connected to said electrical heater ( 6 ), said electrical heater ( 6 ) comprising heater sections having different heating resistance values which depend on a spacing between any particular heater section and said tip ( 10 ) of said sensor carrier section, said different heating resistance values generating varying amounts of heat for compensating said varying heat dissipations, said gas sensor further comprising at least one temperature sensing conductor path ( 12 ) electrically connected to said electrical heater ( 6 ) at least at one contact point, wherein said at least one contact point between said electrical heater ( 6 ) and said at least one temperature sensing conductor path ( 12 ) is positioned on said sensor carrier section for measuring an operating temperature of said sensor carrier section to provide a closed loop control signal for said electrical heater to maintain said operating temperature at a minimal temperature gradient throughout said gas sensor function layer, wherein said electrical heater ( 6 ) comprises two meandering heater paths ( 6 A, 6 B) and an intermediate non-meandering heater portion ( 6 C) positioned next to said tip ( 10 ), said intermediate non-meandering heater portion ( 6 C) electrically connecting said two meandering heater paths ( 6 A, 6 B) in series with each other, said meandering heater paths ( 6 A, 6 B) having amplitudes forming said heater sections, and wherein said amplitudes except a first largest amplitude of said meandering heater paths are diminishing in their size relative to and from said first largest amplitude toward said tip ( 10 ) depending on said spacing between any particular heater section formed by a respective amplitude and said tip ( 10 ).