Microfabricated pressure and shear stress sensors

• US 7,509,869 B2
• Filed: 07/20/2007
• Issued: 03/31/2009
• Est. Priority Date: 06/06/2003
• Status: Active Grant

• Current Assignee: Board of Trustees of The University of Illinois
• Original Assignee: Board of Trustees of The University of Illinois
• Inventors: Chen, Jack, Engel, Jonathan, Liu, Chang
• Primary Examiner(s): Thompson; Jewel
• Application Number:
  US11/880,134
• Publication Number:
  US 20080022778A1
• Time in Patent Office: 620 Days
• Field of Search: 732/042.6, 732/041.6, 732/041.1, 732/042.3, 737/24, 737/26, 737/18
• US Class Current: 73/756
• CPC Class Codes: G01F 1/28 by drag-force, e.g. vane type or impact flowmeter
• CPC Class Codes: G01F 1/6845 Micromachined devices
• CPC Class Codes: G01K 7/015 using microstructures, e.g. made of silicon
• CPC Class Codes: G01K 7/186 using microstructures
• CPC Class Codes: G01L 19/0092 Pressure sensor associated with other sensors, e.g. for measuring acceleration or temperature G01L9/025, G01L9/045, G01L9/065, G01L9/085, G01L9/105, G01L9/125, G01L19/02, G01L19/04 take precedence; measuring two or more variable G01D21/02; temperature sensors with pressure compensation G01K1/26
• CPC Class Codes: G01L 5/228 using tactile array force sensors
• CPC Class Codes: G01N 13/00 Investigating surface or boundary effects, e.g. wetting power; Investigating diffusion effects; Analysing materials by determining surface, boundary, or diffusion effects scanning-probe techniques or apparatus G01Q
• CPC Class Codes: G01N 2203/0676 Force, weight, load, energy, speed or acceleration
• CPC Class Codes: G01P 5/12 using variation of resistance of a heated conductor
• CPC Class Codes: Y10T 29/49103 Strain gauge making

Abstract

A microfabricated pressure sensor. The pressure sensor comprises a raised diaphragm disposed on a substrate. The diaphragm is configured to bend in response to an applied pressure difference. A strain gauge of a conductive material is coupled to a surface of the raised diaphragm and to at least one of the substrate and a piece rigidly connected to the substrate.

Claims

1. A microfabricated pressure sensor comprising:

a polymer film providing a raised diaphragm, the raised diaphragm being disposed on a flexible polymer substrate, said diaphragm being configured to bend in response to an applied pressure difference;

a strain gauge of a conductive material coupled to a surface of the raised diaphragm and to at least one of the substrate and a piece rigidly connected to the substrate.

3. The pressure sensor of claim 1, wherein the surface of the raised diaphragm is exposed.

4. The pressure sensor of claim 1, wherein the strain gauge comprises a nichrome film formed on the surface of the raised diaphragm.

5. The pressure sensor of claim 1, wherein the polymer film comprises Parylene.

6. The pressure sensor of claim 5, wherein the substrate comprises polyimide.

7. The pressure sensor of claim 1, further comprising:

a plurality of additional pressure sensors disposed in an array on a surface of the substrate, each of said plurality of pressure sensors comprising;

an additional polymer film providing an additional raised diaphragm, the additional raised diaphragm being disposed on the substrate; and

an additional strain gauge of a conductive material coupled to a surface of the additional raised diaphragm and to the substrate.

8. The pressure sensor of claim 7, wherein the array is two-dimensional.

2. A microfabricated shear stress sensor comprising:

a polymer film providing a raised membrane, the raised membrane being disposed on a flexible polymer substrate;

a heated hot-wire element disposed on a surface of the membrane for sensing fluid stress.

9. The shear stress sensor of claim 2, wherein the surface of the raised membrane is exposed.

10. The shear stress sensor of claim 2, wherein the heated hot-wire element comprises a nickel thermoresistor formed on the surface of the raised membrane.

11. The shear stress sensor of claim 2, wherein the polymer film comprises Parylene.

12. The shear stress sensor of claim 11, wherein the substrate comprises polyimide.

13. The shear stress sensor of claim 2, further comprising:

a plurality of additional shear stress sensors disposed in an array on a surface of the substrate, each of said plurality of shear stress sensors comprising;

an additional polymer film providing an additional raised membrane, the additional raised membrane being disposed on the substrate; and

an additional heated hot-wire element disposed on a surface of the additional raised membrane.

14. The shear stress sensor of claim 13, wherein the array is two-dimensional.

15. A fluid flow sensing device comprising:

an array of sensor nodes disposed on a flexible polymer substrate, each of the sensor nodes comprising at least one microfabricated pressure sensor and at least one microfabricated shear stress sensor;

wherein each of the at least one microfabricated pressure sensor comprises a first polymer film providing a raised diaphragm, the raised diaphragm being disposed on the flexible polymer substrate, said raised diaphragm being configured to bend in response to an applied pressure difference, and a strain gauge of a conductive material coupled to a surface of the raised diaphragm and to at least one of the substrate and a piece rigidly connected to the substrate;

wherein each of the at least one microfabricated shear stress sensor comprises a second polymer film providing a raised membrane, the raised membrane being disposed on the flexible polymer substrate, and a heated hot-wire element disposed on a surface of the membrane for sensing fluid stress.

16. The fluid flow sensing device of claim 15, wherein the array is two-dimensional.

17. The fluid flow sensing device of claim 15, wherein the first polymer film and the second polymer film comprise Parylene.

18. The fluid flow sensing device of claim 17, wherein the flexible polymer substrate comprises polyimide.