SENSING DEVICES AND METHODS

• US 20120036917A1
• Filed: 08/11/2011
• Published: 02/16/2012
• Est. Priority Date: 08/11/2010
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Avramescu, Viorel, Bostan, Cazimir G., Georgescu, Ion
• Granted Patent: US 9,097,638 B2
• Time in Patent Office: Days
• US Class Current: 73/24.04
• CPC Class Codes: G01N 2291/02845 Humidity, wetness
• CPC Class Codes: G01N 2291/02881 Temperature
• CPC Class Codes: G01N 2291/0423 Surface waves, e.g. Rayleigh waves, Love waves
• CPC Class Codes: G01N 2291/106 one or more transducer arrays
• CPC Class Codes: G01N 29/022 Fluid sensors based on microsensors, e.g. quartz crystal-microbalance [QCM], surface acoustic wave [SAW] devices, tuning forks, cantilevers, flexural plate wave [FPW] devices microdevices per se B81B
• CPC Class Codes: G01N 29/2481 Wireless probes, e.g. with transponders or radio links
• CPC Class Codes: G01N 29/30 Arrangements for calibrating or comparing, e.g. with standard objects
• CPC Class Codes: Y10T 29/42 Piezoelectric device making

Abstract

Embodiments of the present disclosure include devices and methods for humidity and temperature sensing. For example, in one embodiment, a sensing device can include a first surface acoustic wave (SAW) component, wherein the first SAW component is a temperature component, a second SAW component, wherein the second SAW component is a humidity component, a third SAW component, wherein the third SAW component is a reference component, and a piezoelectric layer, wherein the first SAW component, the second. SAW component, and the third SAW component are on a surface of the piezoelectric layer.

Claims

1. A sensing device, comprising:

a first surface acoustic wave (SAW) component, wherein the first SAW component is a temperature component;

a second SAW component, wherein the second SAW component is a humidity component;

a third SAW component, wherein the third SAW component is a temperature reference; and

a piezoelectric layer, wherein the first SAW component, the second SAW component, and the third SAW component are on a surface of the piezoelectric layer.

2. The sensing device of claim 1, wherein the first SAW component, the second SAW component, and the third SAW component are resonators.

3. The sensing device of claim 1, wherein the first SAW component, the second SAW component, and the third SAW component are delay line components.

4. The sensing device of claim 1, wherein the second SAW component has a resonant frequency that is affected mainly by temperature and humidity.

5. The sensing device of claim 1, wherein the first SAW component has a resonant frequency that is affected mainly by temperature.

6. The sensing device of claim 1, wherein the first and third SAW components are sealed from the environment surrounding the sensing device and the second SAW component is exposed to the environment surrounding the sensing device.

7. The sensing device of claim 1, wherein the sensing device includes an antenna to transmit frequency data from the first, second, and third SAW components.

8. The sensing device of claim 1, wherein the piezoelectric layer is quartz.

9. The sensing device of claim 1, wherein the sensing device includes a cover coupled to the piezoelectric layer and the cover is made of the same material as the piezoelectric layer.

10. A method of forming a sensing device, comprising:

forming a first SAW component, a second SAW component, and a third SAW component on a surface of a piezoelectric layer;

forming a first reflector assembly, a second reflector assembly, and a third reflector assembly on the surface of the piezoelectric layer;

coupling a cover to the surface of the piezoelectric layer; and

forming an opening in the cover to expose the second SAW component to the environment surrounding the sensing device.

11. The method of claim 10, wherein coupling the cover to the surface of the piezoelectric layer includes bonding the cover to the surface of the piezoelectric layer using glass frit.

12. The method of claim 10, wherein coupling the cover to the surface of the piezoelectric layer seals the first SAW component and the third SAW component from the environment surrounding the sensing device.

13. The method of claim 10, wherein the method includes forming a first electrical connection and a second electrical connection on the surface of the piezoelectric layer coupled to the first, second, and third SAW components.

14. The method of claim 13, wherein the method includes coupling the first and second electrical connections to an interrogator unit.

15. The method of claim 10, wherein forming the first SAW component includes forming the first SAW component so the direction of propagation of the surface waves are at an angle with respect to the direction of propagation of the surface waves for the second and third SAW components.

16. A sensing device assembly comprising:

a reference SAW component;

a humidity SAW component;

a temperature SAW component;

a piezoelectric layer, wherein the reference, humidity, and temperature SAW components are on a surface of the piezoelectric layer;

a cover coupled to the piezoelectric layer, wherein the cover seals the reference SAW component and the temperature SAW component from the environment surrounding the sensing device and the cover includes an opening to expose the humidity SAW component to the environment surrounding the sensing device; and

wherein the normalized humidity frequency is the difference between the resonant frequency of the SAW humidity component and the resonant frequency of the SAW reference component and is calibrated to correlate to relative humidity and the normalized temperature frequency is the difference between the resonant frequency of the SAW temperature component and the resonant frequency of the SAW reference component and is calibrated to correlate to temperature.

17. The sensing device assembly of claim 16, wherein the sensing device assembly includes an antenna.

18. The sensing device assembly of claim 17, wherein the antenna wirelessly communicates with an interrogator to send piezoelectric layer surface frequency data from the reference, humidity, and temperature SAW components from the sensing device to the interrogator.

19. The sensing device of claim 16, wherein the cover is coupled to the piezoelectric layer by glass frit.

20. The sensing device of claim 16, wherein waves generated on the surface of the piezoelectric layer by the reference, humidity, and temperature SAW components are used by a transducer to generate electrical power which is used to send electromagnetic waves with piezoelectric layer surface frequency data from the antenna to the interrogator.