Flow sensor with thermocouples

A device for measuring a flow of a fluid comprising

• a substrate, wherein said substrate is divided into a measuring region and a regular region, wherein a thermal conductance in said measuring region is lower than a thermal conductance in said regular region,
• a heater arranged at least partially on said measuring region,
• at least one sensing thermocouple for generating a sensing signal, said sensing thermocouple being arranged at least partially on said measuring region, wherein a junction of said sensing thermocouple closest to said heater is arranged at a first distance from said heater,
• a control circuit adapted to measure the flow of the fluid over said heater and said sensing thermocouple from a flow-dependent heating of said sensing thermocouple by said heater, and
• in addition to and distinct from the sensing thermocouple at least one monitoring thermocouple for generating a monitoring signal, said monitoring thermocouple being arranged completely on said measuring region, wherein a junction of said monitoring thermocouple closest to said heater is arranged at a second distance from said heater, wherein said second distance is smaller than said first distance, wherein said sensing thermocouple extends parallel to said monitoring thermocouple.

A device for measuring a flow of a fluid comprising

• a substrate,
• a heater arranged on said substrate, wherein said heater comprises several conductors with at least one gap between said conductors,
• at least one sensing thermocouple for generating a sensing signal, said sensing thermocouple being arranged on said substrate, wherein a junction of said sensing thermocouple closest to said heater is arranged at a first distance from said heater,
• a control circuit adapted to measure the flow of the fluid over said heater and said sensing thermocouple from a flow-dependent heating of said sensing thermocouple by said heater, and
• in addition to and distinct from the sensing thermocouple a plurality of monitoring thermocouples for generating a monitoring signal, said monitoring thermocouples being arranged in said gap and comprising a first bar of a first material extending from a first end of said heater to a center of said heater and a second bar of a second material connected at said center of said heater to said first bar and extending to a second end of said heater.

A device for measuring a flow of a fluid comprising

• a substrate,
• a heater arranged on said substrate,
• at least one sensing thermocouple for generating a sensing signal, said sensing thermocouple being arranged on said substrate, wherein a junction of said sensing thermocouple closest to said heater is arranged at a first distance from said heater,
• a control circuit adapted to measure the flow of the fluid over said heater and said sensing thermocouple from a flow-dependent heating of said sensing thermocouple by said heater,
• in addition to and distinct from the sensing thermocouple at least one monitoring thermocouple for generating a monitoring signal, wherein said monitoring thermocouple is arranged on said substrate, wherein a junction of said monitoring thermocouple closest to said heater is arranged at a second distance from said heater, wherein said second distance is smaller than said first distance and
• an analog/digital converter for converting said sensing signal, wherein said analog/digital converter has a reference input and generates a digitized value of said sensing signal normalized by a signal at said reference input, wherein said monitoring signal is applied to said reference input.