Sensor package for harsh environments

• US 6,911,894 B2
• Filed: 04/22/2002
• Issued: 06/28/2005
• Est. Priority Date: 12/07/1998
• Status: Expired due to Term

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Bonne, Ulrich, Satren, Ernest
• Primary Examiner(s): Easthom, Karl D.
• Application Number:
  US10/128,775
• Publication Number:
  US 20030107467A1
• Time in Patent Office: 1,163 Days
• Field of Search: 338/25, 338/28, 732/041.2, 732/041.3, 732/042.2, 732/042.5
• US Class Current: 338/25
• CPC Class Codes: G01F 1/6842 with means for influencing the fluid flow
• CPC Class Codes: G01F 1/6845 Micromachined devices
• CPC Class Codes: G01F 1/6847 where sensing or heating elements are not disturbing the fluid flow, e.g. elements mounted outside the flow duct
• CPC Class Codes: G01F 5/00 Measuring a proportion of the volume flow
• CPC Class Codes: G01N 1/2247 Sampling from a flowing stream of gas
• CPC Class Codes: G01N 2001/2285 Details of probe structures
• 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
• CPC Class Codes: G01N 25/488 Details
• CPC Class Codes: G01N 33/0014 by eliminating a gas G01N33/0013 and G01N33/0024 take precedence

Abstract

A sensor can be configured to generally include a flow channel block having a flow channel formed therein, and a sensor chip for sensing fluid flow, wherein a fluid in the flow channel surrounds the sensor chip. Alternatively, the sensor chip can be fastened at one side to a substrate and on another side of the substrate to a core tube inserted into the flow channel. This core tube provides electrical insulation and corrosion protection to the sensor chip, reduces flow noise, (and by the non-intrusive nature of the measurement) essentially eliminates the risk of fluid leakage, and maintains the fluid super-clean and contamination-free while improving structural integrity for the thermal measurements derived from the sensor chip. The use of such a core tube configuration also can protect the sensor from corrosion, radioactive or bacterial contamination, overheating, or freeze-ups. Such a core tube configuration also enables the core tube to be detachable and disposable, without requiring the replacement of the more costly sensor chip with its electronics and calibration.

Claims

1. A system for detecting fluids in harsh environments, said system comprising:

a flow channel block having a flow channel formed therein;

a microsensor chip for sensing fluid flow, wherein said microsensor chip is located proximate to said flow channel of said flow channel block and wherein said microsensor chip comprises a thermal microsensor that includes at least one sensing element for sensing a fluid parameter based on heat transfer and thermal conductivity;

a substrate in communication with said microsensor chip and at least one electrical contact bonded to it by at least one bonding element, wherein said flow channel is connected to said microsensor chip by a material that facilitates heat transfer and which is disposable upon completion of a fluid measurement;

a disposable core tube for molding said flow channel, wherein said disposable flow core tube possesses walls thereof and is removably located within said flow channel block to thereby permit detection of liquid flow in harsh environments through said walls of said core tube; and

wherein said walls of said disposable core tube comprise a wall thickness that removes said surface of said microsensor chip from direct contact with said fluid by a distance corresponding to said wall thickness.

2. The system of claim 1 further comprising a thin film applied to said at least one sensing element, wherein said thin film is applied thinly and comprises a self-supporting layer.

3. The sensor of claim 2 wherein said thin film layer is laminated with an electrical insulating material to provide hermetic sealing thereof.

4. The sensor of claim 1 wherein said microsensor chip is exposed to a fluid following a molding of said flow channel via said disposable core tube.

5. The sensor of claim 1 wherein said microsensor chip is shielded from a fluid when said disposable core tube is left in place within said flow channel block and wherein said substrate comprises silicon.

6. A system for detecting fluid in harsh environments, said system comprising:

a flow channel block having a flow channel formed therein, wherein said flow channel block is configured in a shape of tube, thereby permitting said flow channel block to comprise a flow tube;

a microsensor chip for sensing fluid flow, wherein said microsensor chip is located proximate to said flow channel of said flow channel block and wherein said microsensor chip comprises a thermal microsensor that includes at least one sensing element for sensing a fluid parameter based on heat transfer and thermal conductivity;

a thin film applied to said at least one sensing element, wherein said thin film is applied thinly;

a substrate comprising glass, wherein said substrate communicates with said microsensor chip and at least one electrical contact bonded to it by at least one bonding element, wherein said removable flow channel is removably connected to said microsensor chip by a material that facilitates heat transfer and which is disposable upon completion of a measurement of a fluid;

a disposable core tube for molding said flow channel, wherein said disposable core tube possesses walls thereof and is located within said flow channel block to thereby permit detection of liquid flow in harsh environments through said walls of said disposable core tube;

wherein said microsensor chip is exposed to said fluid following a molding of said flow channel via said core tube, if said disposable core tube is removed from said flow channel block; and

wherein said walls of said core tube possess a wall thickness that prevents a surface of said microsensor chip from direct contact with a fluid flowing through said core tube by a distance corresponding to said wall thickness, if said disposable core tube remains within said flow channel block.

7. The system of claim 6 wherein said disposable core tube comprises a constriction in a cross section of said disposable core tube at said microsensor chip.

8. The system of claim 6 wherein said disposable core tube and said substrate are replaceable by a flat film wrapped about a header and sealed by an O-ring to provide thermal conductivity measurement sensor capabilities thereof, in a zero forced-convection environment.

9. The system of claim 6 wherein a thickness of said thin film applied to said at least one sensing element is in an inclusive range of approximately 0.0001-in to 0.010-in.

10. The system of claim 9 wherein said thin film comprises a self-supporting layer.

11. The system of claim 10 further comprising an electrical insulating material laminated over said thin film to provide hermetic sealing thereof.

12. The system of claim 11 wherein said electrical insulating material comprises a polymeric material.

13. A system for detecting fluids in harsh environments, said system comprising:

a flow channel block having a flow channel formed therein;

a microsensor chip for sensing fluid flow, wherein said microsensor chip is located proximate to said flow channel of said flow channel block and wherein said microsensor chip comprises a thermal microsensor that includes at least one sensing element for sensing a fluid parameter based on heat transfer and thermal conductivity;

a substrate in communication with said microsensor chip and at least one electrical contact bonded to it by at least one bonding element, wherein said flow channel is connected to said microsensor chip by a material that facilitates heat transfer and which is disposable upon completion of a fluid measurement; and

a disposable core tube for molding said flow channel, wherein said disposable flow core tube possesses walls thereof and is removably located within said flow channel block to thereby permit detection of liquid flow in harsh environments through said wails of said core tube; and

wherein said microsensor chip is shielded from a fluid when said disposable core tube is left in place within said flow channel block and wherein said substrate comprises silicon.

14. The system of claim 13 further comprising a thin film applied to said at least one sensing element, wherein said thin film is applied thinly and comprises a self-supporting layer.

15. The sensor of claim 14 wherein said thin film layer is laminated with an electrical insulating material to provide hermetic sealing thereof.

16. The sensor of claim 13 wherein said microsensor chip is exposed to a fluid following a molding of said flow channel via said disposable core tube.