Fluid sensor including an error detection device

• US 7,360,392 B2
• Filed: 03/07/2007
• Issued: 04/22/2008
• Est. Priority Date: 03/09/2006
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Konzelmann, Uwe, Wagner, Ulrich, Gmelin, Christoph, Baumann, Martin
• Primary Examiner(s): Williams; Hezron
• Assistant Examiner(s): FITZGERALD, JOHN P
• Application Number:
  US11/715,573
• Publication Number:
  US 20070289356A1
• Time in Patent Office: 412 Days
• Field of Search: 73/10.2, 73/10.6
• US Class Current: 73/1.02
• CPC Class Codes: G01N 25/18 by investigating thermal conductivity by calorimetry G01N25/20; by measuring change of resistance of an electrically-heated body G01N27/18

Abstract

A fluid sensor may be used for detecting fluid media, in particular hydrogen. The fluid sensor includes a sensor chip having a chip surface, which has a measuring surface and a body surface. Printed conductors of a central sensor circuit having at least one heating element and at least one temperature sensor are provided on the measuring surface. Furthermore, the fluid sensor has one additional fracture detection element and one fracture detection circuit situated on the sensor chip. The fracture detection circuit is designed for detecting fractures and/or cracks in and/or on the sensor chip, in particular in the area of a boundary between the measuring surface and body surface.

Claims

1. A fluid sensor for detecting fluid media, comprising:

a sensor chip having a chip surface which can be exposed to the fluid medium, the chip surface having a measuring surface and a body surface, and having printed conductors of a central sensor circuit having at least one heating element and at least one temperature sensor situated on the measuring surface;

at least one fracture detection element situated on the sensor chip; and

a fracture detection circuit for detecting at least one of (a) fractures and (b) cracks, in and/or on the sensor chip.

2. The fluid sensor according to claim 1, wherein the fluid media include gases.

3. The fluid sensor according to claim 1, wherein the detection is performed in an area of a boundary between the measuring surface and the body surface.

4. The fluid sensor according to claim 1, wherein the at least one fracture detection element includes at least one fracture detector printed conductor.

5. The fluid sensor according to claim 4, wherein the at least one fracture detector printed conductor extends in at least one area in one of a serpentine and meander pattern in an area of a boundary between the measuring surface and the body surface.

6. The fluid sensor according to claim 4, wherein the at least one fracture detector printed conductor includes at least one first printed conductor segment extending on the measuring surface at least substantially parallel to a boundary between the measuring surface and the body surface and at least one second printed conductor segment extending on the body surface at least substantially parallel to the boundary between the measuring surface and the body surface.

7. The fluid sensor according to claim 4, wherein the at least one fracture detector printed conductor crosses a boundary between the measuring surface and the body surface a plurality of times, in at least one area.

8. The fluid sensor according to claim 7, wherein the conductor crosses the boundary perpendicularly.

9. The fluid sensor according to claim 1, wherein the at least one fracture detection element is situated in at least one area on the measuring surface at a distance of 10 to 100 micrometers from a boundary between the measuring surface and the body surface.

10. The fluid sensor according to claim 9, wherein the distance is 20 to 50 micrometers.

11. The fluid sensor according to claim 9, wherein the distance is 25 micrometers.

12. The fluid sensor according to claim 1, wherein the at least one fracture detection element is situated in at least one area on the body surface at a distance of 10 to 100 micrometers from a boundary between the measuring surface and the body surface.

13. The fluid sensor according to claim 12, wherein the distance is 20 to 50 micrometers.

14. The fluid sensor according to claim 12, wherein the distance is 25 micrometers.

15. The fluid sensor according to claim 1, wherein the fracture detection circuit includes at least one circuit for detecting a resistance.

16. The fluid sensor according to claim 15, wherein the fracture detection circuit further includes at least one threshold circuit for comparing the detected resistance with at least one threshold value and generating at least one control signal as a function of a result of the comparison.