RESONATOR SENSOR ASSEMBLY

• US 20100218353A1
• Filed: 05/19/2010
• Published: 09/02/2010
• Est. Priority Date: 03/21/2003
• Status: Active Grant

• Current Assignee: Hella KGaA Hueck & Company, Meas France
• Original Assignee: Hella KGaA Hueck & Company, Meas France
• Inventors: Wullner, Dirk, Lüdtke, Olaf, Buhrdorf, Andreas, Dobrinski, Heiko, Varni, John F., Dales, G. Cameron, Matsiev, Leonid, Kolosov, Oleg
• Granted Patent: US 8,732,938 B2
• Time in Patent Office: Days
• US Class Current: 29/25.350
• CPC Class Codes: G01F 23/2966 making use of acoustical resonance or standing waves
• CPC Class Codes: G01N 2009/006 vibrating tube, tuning fork
• CPC Class Codes: G01N 2291/0427 Flexural waves, plate waves, e.g. Lamb waves, tuning fork, cantilever
• CPC Class Codes: Y10T 29/42 Piezoelectric device making
• CPC Class Codes: Y10T 29/49005 Acoustic transducer
• CPC Class Codes: Y10T 29/4908 Acoustic transducer

Abstract

An improved method and assembly, wherein the method generally includes the steps of providing a coated or uncoated sensor element having an exposed sensing surface; attaching the sensor element to a platform so that the exposed sensing surface is spaced from the platform; and optionally applying a protective layer over the platform while maintaining the sensing surface as exposed. The assembly includes a resonator having a free portion with a sensing surface is incorporated onto a platform, components of the sensor are physically shielded from harsh operating conditions, the requisite space is maintained between the free portion of the resonator and the platform, and the sensing surface of the resonator remains exposed for sensing.

Claims

1. A method of packaging a sensor, the method comprising:

affixing a tuning fork to a platform, the tuning fork having tines comprising one or more surfaces, each tine further comprising an electrode;

affixing an application specific integrated circuit (ASIC) to the platform, and

providing electrical communication between the ASIC and the electrode of each tine for providing stimulus to the tuning fork and for receiving a response signal from the tuning fork.

2. The method of claim 1, wherein each tine further comprises a piezoelectric material and wherein the electrodes are positioned to apply electric fields to the piezoelectric materials in the respective tines to move the tines relative to the platform to displace a fluid in contact with the tines.

3. The method of claim 2, further including applying a protective layer covering the platform and the tuning fork while maintaining the surface of the tine such that the surface can displace the fluid in contact therewith.

4. The method of claim 3, wherein the protective layer is selectively applied by spraying, brushing, over molding, laminating or by combinations thereof.

5. The method of claim 4, further including blocking the surface with a removable protective barrier prior to applying the protective layer.

6. The method of claim 5, wherein the removable protective barrier is a consumable barrier that comprises a polymer, starch, wax, salt or other dissolvable crystal, low melting point metal, a photoresist, or another sacrificial material.

7. The method of claim 5 wherein the removable protective barrier is a reusable barrier that comprises a relatively soft material that will not plastically deform the tuning fork if it contacts the tuning fork.

8. The method of claim 1, further including affixing a secondary component on the platform and spaced from the ASIC, the secondary component being selected from a group consisting of a temperature sensor, a field programmable gate array, a calibration unit, a conductive path, a resistor, a capacitor, an amplifier, a filter, and combinations of two or more thereof.

9. The method of claim 8, further including providing electrical communication between the ASIC and the secondary component.

10. The method of claim 1, further including at least partially protecting the tuning fork from ambient or operational conditions through the use of a housing.

11. The method of claim 1, further comprising operating the tuning fork at temperatures between about −

60°

C. and about 300°

C.

12. The method of claim 1, wherein the tuning fork has a length or width smaller than about 5 mm.

13. The method of claim 1, wherein the platform having the tuning fork and the ASIC affixed thereto defines a package, the package having a volume of about less than about 15 cm³.

14. The method of claim 1, wherein the platform having the tuning fork and the ASIC affixed thereto defines a package, the package having a footprint of about less than about 40 cm².

15. A method of assembling a fluid sensor, the method comprising:

disposing a flexure resonator on a base, the flexure resonator comprising at least two prongs each having an electrode;

disposing a control circuit on the base, and

operatively connecting the control circuit to the electrodes for at least one of transmitting a signal to and receiving a signal from the flexure resonator.

16. The method of claim 15, further including applying a protective layer covering the base and the flexure resonator.

17. The method of claim 16, further including blocking a portion of the flexure resonator with a removable protective barrier prior to applying the protective layer.

18. The method of claim 15, further including disposing a Faraday cage around the flexure resonator.

19. The method of claim 15, further including placing the sensor in one of an engine, a transmission, a transfer case, a differential, a brake system, a steering system, an antifreeze system, a heating and cooling system, a washer system, or combinations thereof.

20. The method of claim 15, further including placing the sensor in one of a lubricant, a brake fluid, a steering fluid, an antifreeze fluid, a refrigerant fluid, a washer fluid, or combinations thereof.