GAS SENSOR USING NANOTUBES

• US 20120006096A1
• Filed: 07/09/2010
• Published: 01/12/2012
• Est. Priority Date: 07/09/2010
• Status: Active Grant

• Current Assignee: Empire Technology Development LLC (Allied Inventors Management, LLC)
• Original Assignee: Napeequa Concepts, LLC
• Inventors: Ackley, H. Sprague, Wiklof, Christopher A.
• Granted Patent: US 8,567,232 B2
• Time in Patent Office: Days
• US Class Current: 73/24.01
• CPC Class Codes: G01N 33/0055 Radionuclides

Abstract

Techniques are generally described for detecting a concentration level of at least one gas. Some example devices may include a sensor including conductive plate on a surface of dielectric including a nanotube layer formed thereon. The conductive plate and the nanotube layer form a resonator that resonates at a frequency in response to an interrogation signal. The nanotube layer may be configured to associate with one or more gas molecules. The frequency at which the resonator resonates may shift according to which gas molecules are associated with the nanotube layer to identify a particular gas. An amount of resonance may be exhibited as a resonant response signal. An amplitude of the resonant response signal may be indicative of the concentration level of the detected gas.

Claims

1. A sensor configured to detect at least first and second gasses in a volume that includes a mixture of two or more gases, the sensor comprising:

a dielectric substrate;

a first conductive plate on a first surface of the dielectric substrate;

a first nanotube layer arranged on the first conductive plate, the first conductive plate in combination with the nanotube layer forming a first resonator, wherein the first resonator is configured to generate a first resonant response signal in response to a first interrogation signal, the first resonant response signal being indicative of a resonance characteristic of the first resonator that changes when the sensor is in contact with the first gas in the volume such that the first resonance characteristic of the first resonator identifies the first gas;

a second conductive plate on the first surface of the dielectric substrate; and

a second nanotube layer arranged on the second conductive plate, the second conductive plate in combination with the second nanotube layer forming a second resonator, wherein the second resonator is configured to generate a second resonant response signal being indicative of a resonance characteristic of the second resonator that changes when the sensor is in contact with the second gas in the volume such that the second resonance characteristic of the second resonator identifies the second gas.

2. The sensor of claim 1, wherein the second resonator is configured to generate a second resonant response signal in response to a second interrogation signal and the first interrogation signal is different from the second interrogation signal.

3. The sensor of claim 1, wherein the first nanotube layer comprises a layer of nanotubes, nanotubes all having substantially a same size.

4. The sensor of claim 1, wherein the first conductive plate comprises a high aspect ratio rectangle or other polygon and the first resonant response signal comprises a bi-modal resonant response.

5. The sensor of claim 1, wherein the first resonator and the second resonator have different sizes.

6. The sensor of claim 1, further comprising at least one feedline configured to provide the interrogation signal to the first resonator and the second resonator, and wherein the interrogation signal has one or more frequencies associated therewith.

7. The sensor of claim 1, further comprising a first feedline configured to selectively provide the interrogation signal to the first resonator, and a second feedline configured to selectively provide the interrogation signal to the second resonator.

9. The sensor of claim 1, wherein the first conductive plate comprises one or more of a circular plate and/or a copper plate.

10. The sensor of claim 1, further comprising a ground plane insulated from and subjacent to the first resonator.

25. The sensor of claim 1, wherein the first nanotube layer comprises nanotubes all having substantially a same diameter.

8. (canceled)

11. A system for detecting first and second gasses in a volume including a mixture of two or more gases, the system comprising:

a signal generator configured to provide at least one interrogation signal;

at least one first sensor configured to receive the at least one interrogation signal, wherein the at least one first sensor includes

a dielectric substrate; and

a first resonator formed from a first nanotube layer arranged on a first conductive plate, and configured to generate a first resonant response signal in response to the at least one interrogation signal, the first resonant response signal being indicative of a resonance characteristic of the first resonator that changes when the at least one first sensor is in contact with the first gas in the volume such that the resonance characteristic of the first resonator identifies the first gas;

at least one second sensor configured to receive a second interrogation signal of the plurality of interrogation signals, wherein the at least one second sensor includes;

a second resonator formed from a second nanotube layer arranged on a second conductive plate on the dielectric substrate, and configured to generate a second resonant response signal in response to the second interrogation signal, the second resonant response signal being indicative of a resonance characteristic of the second resonator that changes when the at least one second sensor is in contact with the second gas in the volume such that the resonance characteristic of the second resonator identifies the second gas; and

a detector configured to receive the first and second resonant response signals and generate a detection signal that indicates the resonance characteristic of the first resonator that identifies the first gas and/or the resonance characteristic of the second resonator that identifies the second gas.

12. The system of claim 11, wherein the signal generator and the detector are part of a sensor interface.

13. The system of claim 11, further comprising a controller that is operatively coupled to the detector and configured to receive the detection signal, wherein the controller is further configured to compare the detection signal with an expected value to determine the presence and/or absence of the first or second gas in the volume.

14. The system of claim 11, wherein the at least one sensor is wirelessly coupled to either the signal generator or the detector.

15. The system of claim 11, further comprising a control sensor including a control resonator, wherein the control sensor is located in a different volume including a known gas, wherein the control resonator is configured to generate a control response signal in response to the first interrogation signal, the control response signal being indicative of a resonance characteristic of the control resonator when the control sensor is in contact with the known gas in the different volume such that the resonance characteristic of the control resonator identifies the known gas.

16. The system of claim 15, further comprising a controller configured to compare the resonance characteristics of the control resonator to the resonance characteristics of the first resonator to identify a difference indicative of the presence of the at least one gas about the at least one first sensor.

17. The system of claim 16, wherein the identified difference corresponds to one or more of a difference in amplitude, a different in Q-factor, a difference in phase, a difference in resonant frequency, a shift in resonant frequency, and/or a difference in a plurality of resonant frequencies.

18. The system of claim 11, the first resonator in the at least one first sensor comprising a layer of carbon nanotubes disposed on a conductive plate and adapted to contact the mixture of two or more gases, wherein the first resonator has a resonant frequency when excited by the interrogation signal, wherein the resonant frequency of the first resonator shifts in the presence of the first gas.

26. The system of claim 11, wherein the first interrogation signal is different from the second interrogation signal.

19. A method for identifying two or more gases in a volume including a mixture of two or more gases, the method comprising:

applying one or more first interrogation signals to a first resonator, the resonator including first carbon nanotubes arranged on a first conductive plate, the first conductive plate on a first surface of a dielectric substrate;

measuring two or more first resonant responses of the first resonator when excited by first interrogation signals; and

applying one or more second interrogation signals to a second resonator, the second resonator including second carbon nanotubes arranged on a second conductive plate, the second conductive plate on a second surface of the dielectric substrate;

measuring two or more second resonant responses of the second resonator when excited by the second interrogation signals; and

determining the identity of two or more gases as a function of the first and second resonant responses, wherein

the first interrogation signals are different from the second interrogation signals.

20. The method of claim 19, wherein

the volume is a first volume,

the second resonator is in contact with a second volume, the second volume being different from the first volume, and

determining the identity of two or more gases comprises determining the identity of two or more gases from a difference between the two or more resonant responses of the first resonator and the two or more resonate responses of the second resonator.

21. The method of claim 20, wherein the first resonator resonates at approximately the same time as the second resonator.

22. The method of claim 19, wherein applying one or more first interrogation signals to the first resonator comprises applying one or more first interrogation signals to a plurality of first resonators, and wherein measuring two or more resonant responses of the first resonator comprises measuring two or more first resonant responses of each first resonator of the plurality of first resonators.

23. A method for identifying a first and second gas in a mixture including two or more gases, comprising:

receiving a radio based interrogation signal including a plurality of interrogation frequencies with an antenna that is operatively coupled to a first and second carbon nanotube resonators; and

generating at least one first resonant response in response to the radio based interrogation signal with the first carbon nanotube resonator, wherein the first resonant response of the first carbon nanotube resonator varies based on contents of the gas mixture that are in contact with the first carbon nanotube resonator;

generating at least one second resonant response in response to the radio based interrogation signal with the second carbon nanotube resonator, wherein the second resonant response of the second carbon nanotube resonator varies based on contents of the gas mixture that are in contact with the second carbon nanotube resonator;

identifying the first gas in contact with the first carbon nanotube resonator based on the at least one first resonant response and

identifying the second gas in contact with the second carbon nanotube resonator based on the at least one second resonant response.

24. The method of claim 23, wherein at least a portion of the antenna includes the first and/or second carbon nanotube resonator.