Energetic pulse clearing of environmentally sensitive thin-film devices

Patent metadata

Field	Value
Publication number	US-11385196-B2
Application number	US-201715695557-A
Country	US
Kind code	B2
Filing date	Sep 5, 2017
Priority date	Sep 5, 2016
Publication date	Jul 12, 2022
Grant date	Jul 12, 2022

Abstract

A process and electronic hardware and software system for rapidly heating and cooling an active sensing layer of a gas sensor is provided. A series of high-energy pulses is run through a CNT electrically-active layer, heating the layer to varying temperatures. The influence by various gases on the electrical conductivity of the layer can be used to identify gases (e.g., water vapor, alcohol, methane, O2, CO2, and CO). Advantageously, the same structure can also be used as a nanoheater, either within or outside the context of the gas sensor. The device can acquire a unique gas spectra in seconds, and thus accurately determine gas type and mixtures of gases based on a library of known spectra.

First claim

The invention claimed is:

1. An environmental sensor comprising:
first and second electrodes formed from electrically conductive material, the electrodes spaced apart from one another and positioned on a substrate,
the first and second electrodes configured to receive a sequence of electric voltage pulses from a high voltage source of about 25 V to about 500 V and a pulse modulator,
the electric voltage pulses having a duration of less than about 100 microseconds;
wherein the pulse modulator fixes a time between the pulses within a pulse train and the duration of the pulses; and
an active sensing layer, the active sensing layer positioned on the substrate and in direct contact with a top surface and left and right side surfaces of each electrode, the active sensing layer configured to experience a change in an electrical characteristic in response to a change in a characteristic of a constituent gas in proximity to the active sensing layer and further configured to receive energy directly from the electric voltage pulses from the electrodes to set a temperature of the active sensing layer to a specific value.

2. The environmental sensor of claim 1 , wherein the electrical characteristic is an electrical resistance.

3. The environmental sensor of claim 1 , further comprising a signal enhancement layer positioned in contact with a top surface of the active sensing layer and configured to react with the constituent gas when contacted by the constituent gas and enhance the change in the electrical characteristic of the active sensing layer.

4. The environmental sensor of claim 3 , wherein the signal enhancement layer is formed from a material selected from the group consisting of selective gas-absorbing materials, selective gas-adsorbing materials, and mixtures thereof.

5. The environmental sensor of claim 4 , wherein the signal enhancement layer includes metal oxides.

6. The environmental sensor of claim 1 , further comprising a filter layer positioned in contact with a top surface of the active sensing layer and configured to isolate the active sensing layer from selected environmental stimuli.

7. The environmental sensor of claim 1 , wherein the active sensing layer comprises carbon nanotubes.

8. The environmental sensor of claim 1 , wherein the active sensing layer is configured to receive thermal energy.

9. An environmental sensor array comprising:
a plurality of pixel sensors, each pixel sensor including first and second electrodes formed from electrically conductive material, the electrodes spaced apart from one another and positioned on a substrate,
the first and second electrodes configured to receive a sequence of electric voltage pulses from a high voltage source of about 25 V to about 500 V and a pulse modulator,
the electric voltage pulses having a duration of less than about 100 microseconds;
wherein the pulse modulator fixes a time between the pulses within a pulse train and the duration of the pulses; and
an active sensing layer, the active sensing layer positioned on the substrate and in direct contact with a top surface and left and right side surfaces of each electrode,
the active sensing layer configured to experience a change in an electrical characteristic in response to a change in a characteristic of a constituent gas in proximity to the active sensing layer and further configured to receive energy directly from the electric voltage pulses from the electrodes to set a temperature of the active sensing layer to a specific value.

10. The environmental sensor array of claim 9 , wherein the active sensing layer of each pixel sensor is individually formed from:
a. a single, uniform composition; or
b. a mixture of compositions.

11. The environmental sensor array of claim 10 , wherein the active sensing layer of at least one pixel sensor is formed from a single, uniform composition and the active sensing layer of at least one pixel sensor is formed from a mixture of compositions.

12. The environmental sensor array of claim 10 , wherein at least one pixel sensor comprises a signal enhancement layer positioned in contact with a top surface of the active sensing layer and configured to react with the constituent gas when contacted by the constituent gas and enhance the change in the electrical characteristic of the active sensing layer.

13. The environmental sensor array of claim 12 , wherein the signal enhancement layer comprises metal oxides.

14. The environmental sensor array of claim 10 , wherein the mixture of compositions comprises a signal enhancement material.

15. The environmental sensor array of claim 14 , wherein the signal enhancement material includes metal oxides.

16. The environmental sensor array of claim 10 , wherein the active sensing layer of each pixel sensor is individually formed from:
a. carbon nanotubes; or
b. carbon nanotubes mixed with a signal enhancement material responsive to a specific constituent gas, the mixture of the carbon nanotubes and the signal enhancement material forming a single layer.

17. The environmental sensor array of claim 16 , wherein the active sensing layer of at least one pixel sensor is formed from carbon nanotubes and the active sensing layer of at least one pixel sensor is formed from carbon nanotubes mixed with a signal enhancement material.

18. The environmental sensor array of claim 9 , wherein the electrical characteristic is an electrical resistance.

19. A method of determining a constituent gas with an environmental sensor, the method comprising:
a. generating a train of electrical pulses that is received by the first and second electrodes of the environmental sensor of claim 1 , the train of electrical pulses configured to set a temperature of the environmental sensor;
b. measuring a first electrical resistance between the first and second electrodes of the environmental sensor during the generation of the train of electrical pulses;
c. repeating a. and b. a plurality of times such that each train of electrical pulses sets the environmental sensor to a different temperature resulting in a first spectrum including a plurality of first resistance measurements, one first resistance measurement for each temperature; and
d. comparing the first spectrum to a plurality of response spectra, each response spectrum corresponding to a thermal spectral response of a successive one of a plurality of constituent gases.

20. The method of claim 19 , further comprising determining which response spectrum most closely matches the first spectrum.

21. The method of claim 19 , wherein each response spectrum corresponds to a thermal spectral response of a plurality of constituent gases in combination and the method further comprises determining which response spectrum most closely matches the first spectrum.

22. The method of claim 19 , further comprising determining a combination response spectrum for each of a plurality of combinations of constituent gases and determining which combination response spectrum most closely matches the first spectrum.

23. The method of claim 19 , wherein each electrical pulse is a pulse of electrical voltage.

24. The method of claim 19 , wherein each electrical pulse is a pulse of electrical current.

25. The method of claim 19 , wherein each train of electrical pulses is generated for a first time period and includes a plurality of electrical pulses, each electrical pulse having a pulse width time duration with the trai

Assignees

• Brewer Science Inc

Inventors

• Giedd Ryan E
• Fury Jonathan J
• Harker Erik
• Landorf Christopher

Classifications

• G01N33/0036

  specially adapted to detect a particular component (physical analysis of gaseous biological material G01N33/497) · CPC title

• G01N33/0031

  comprising two or more sensors, e.g. a sensor array · CPC title

• G01N27/123

  for controlling the temperature (temperature control per se G05D23/00) · CPC title

• G01N27/14 Primary

  of an electrically-heated body in dependence upon change of temperature · CPC title

• G01N27/128

  Microapparatus · CPC title