IP Library › Granted Patent US 12,339,245
Granted Patent B2
US 12,339,245 · App. 17/601,389 · Granted Jun 24, 2025

Methods and systems for determining a target gas concentration in a fluid environment

Inventors: Dylan Thomas (Canyon Country, CA); Tim Howard (Canyon Country, CA)
Assignee: H2Scan Corporation
G01N27/122G01N27/046G01N33/0004
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Quick Facts
Patent No.
US 12,339,245
App. No.
17/601,389
Granted
Jun 24, 2025
Kind
B2
Abstract

A system and method of determining a target gas concentrations in a fluid environment using a gas sensor that improves the efficiency and accuracy of the gas sensor's measurements by taking measurements of electrical characteristics of the gas sensor at different temperatures, taking measurements during a transition between a first temperature and a second temperature, taking more frequent measurements, detecting when the gas sensor has reached equilibrium, using multiple sensors, accounting for offsets and drifts, reducing the time the sensor is not live, using various algorithms, or any combination thereof.

Claims (107)

1. A method of determining a target gas concentration of a target gas in a fluid environment, the method comprising the steps of:

(a) exposing a gas sensor to the fluid environment, the gas sensor having an electrical characteristic that varies as a function of the target gas concentration;

(b) during step (a) modulating the temperature of the gas sensor, wherein the modulation is in a form of a repeating thermal waveform that induces a magnitude-frequency response in the electrical characteristics;

(c) monitoring the electrical characteristics during step (b); and

(d) calculating the target gas concentration as a function of the magnitude-frequency response of the electrical characteristics of the gas sensor, wherein the repeating thermal waveform is generated by a superposition of multiple sine waves, wherein each sine wave has a corresponding magnitude-frequency response calibration table.

2. The method of claim 1 , wherein the calibration table is generated by associating the target gas concentration with the magnitude-frequency response measured using a Short Time Fourier Transform.

3. The method of claim 2 , further comprising correcting a shift in the magnitude-frequency response by applying a known partial pressure of the target gas to the sensor, allowing the sensor to generate a second magnitude-frequency response, and applying a correction to the calibration table based on the second magnitude-frequency response.

4. The method of claim 2 , further comprising applying a correction to the calibration table by:

(a) allowing the sensor to generate a second magnitude-frequency response;

(b) changing an operating mode of the gas sensor to operate at two temperatures;

(c) alternately controlling the temperature of the gas sensor between a first temperature and a second temperature while the gas sensor is exposed to the gas, wherein the temperature of the gas sensor remains at the first temperature over a first period of time, transitions from the first temperature to the second temperature over a second period of time, remains at the second temperature over a third period of time, and transitions from the second temperature to a third temperature over a fourth period of time;

(d) monitoring the electrical characteristic of the gas sensor during the second and fourth periods of time;

(e) calculating the target gas concentration as a function of the electrical characteristics; and

(f) calculating the correction based on the second magnitude-frequency response and the calculated target gas concentration.

5. The method of claim 1 , wherein the multiple sine waves comprise a first set of sine waves having a first set of frequencies, and a second set of sine waves having a second set of frequencies, wherein the first set of frequencies is lower than the second set of frequencies, and wherein calculation of the target gas concentration is based on the magnitude-frequency response of one of the first set of frequencies or the second set of frequencies.

6. A method of determining a target gas concentration of a target gas in a fluid environment, the method comprising the steps of:

(a) exposing a gas sensor to the fluid environment, the gas sensor having an electrical characteristic that varies as a function of the target gas concentration;

(b) during step (a) modulating the temperature of the gas sensor, wherein the modulation is in a form of a repeating thermal waveform that induces a phase-frequency response in the electrical characteristics;

(c) monitoring the electrical characteristics during step (b); and

(d) calculating the target gas concentration as a function of the phase-frequency response of the electrical characteristics of the gas sensor, wherein the repeating thermal waveform is generated by a superposition of multiple sine waves, wherein each sine wave has a corresponding phase-frequency response calibration table.

7. The method of claim 6 , wherein the calibration table is generated by associating the target gas concentration with the phase-frequency response measured using a Short Time Fourier Transform.

8. The method of claim 7 , further comprising correcting a shift in the phase-frequency response by applying a known partial pressure of the target gas to the sensor, allowing the sensor to generate a second phase-frequency response, and applying a correction to the calibration table based on the second phase-frequency response.

9. The method of claim 7 , further comprising applying a correction to the calibration table by:

(a) allowing the sensor to generate a second phase-frequency response;

(b) changing an operating mode of the gas sensor to operate at two temperatures;

(c) alternately controlling the temperature of the gas sensor between a first temperature and a second temperature while the gas sensor is exposed to the gas, wherein the temperature of the gas sensor remains at the first temperature over a first period of time, transitions from the first temperature to the second temperature over a second period of time, remains at the second temperature over a third period of time, and transitions from the second temperature to a third temperature over a fourth period of time;

(d) monitoring the electrical characteristic of the gas sensor during the second and fourth periods of time;

(e) calculating the target gas concentration as a function of the electrical characteristics; and

(f) calculating the correction based on the second phase-frequency response and the calculated target gas concentration.

10. The method of claim 6 , wherein the multiple sine waves comprise a first set of sine waves having a first set of frequencies, and a second set of sine waves having a second set of frequencies, wherein the first set of frequencies is lower than the second set of frequencies, and wherein calculation of the target gas concentration is based on the phase-frequency response of one of the first set of frequencies or the second set of frequencies.

11. A method of determining a target gas concentration of a target gas in a fluid environment, comprising:

(a) exposing a first gas sensor to the fluid environment, the first gas sensor having an electrical characteristic that varies as a function of the target gas concentration, and monitoring electrical characteristics of the first gas sensor;

(b) exposing a second gas sensor to the fluid environment, the second gas sensor having an electrical characteristic that varies as a function of the target gas concentration;

(c) alternately controlling the temperature of the second gas sensor between a first temperature and a second temperature while the second gas sensor is exposed to the fluid environment, wherein the temperature of the second gas sensor remains at the first temperature over a first period of time, transitions from the first temperature to the second temperature over a second period of time, remains at the second temperature over a third period of time, and transitions from the second temperature to a third temperature over a fourth period of time;

(d) monitoring the electrical characteristic of the second gas sensor during the second and fourth periods of time; and

(e) calculating the target gas concentration as a function of the electrical characteristic of the first gas sensor, wherein data from the second gas sensor is used to correct for baseline sensor drift of the first gas sensor, wherein the third temperature of the second gas sensor is equal to the first temperature.

12. The method of claim 11 , wherein the first gas sensor operates at a single temperature.

13. The method of claim 12 , wherein the second gas sensor is in a constant state of system response to a repeating thermal waveform.

14. The method of claim 13 , further comprising the first gas sensor reporting to the second gas sensor, a change in a partial pressure of the target gas detected in the first gas sensor.

15. A method of determining a target gas concentration of a target gas in a fluid environment, comprising:

(a) exposing a first gas sensor to the fluid environment, the first gas sensor having an electrical characteristic that varies as a function of the target gas concentration, and monitoring electrical characteristics of the first gas sensor;

(b) exposing a second gas sensor to the fluid environment, the second gas sensor having an electrical characteristic that varies as a function of the target gas concentration;

(c) alternately controlling the temperature of the second gas sensor between a first temperature and a second temperature while the second gas sensor is exposed to the fluid environment, wherein the temperature of the second gas sensor remains at the first temperature over a first period of time, transitions from the first temperature to the second temperature over a second period of time, remains at the second temperature over a third period of time, and transitions from the second temperature to a third temperature over a fourth period of time;

(d) monitoring the electrical characteristic of the second gas sensor during the second and fourth periods of time; and

(e) calculating the target gas concentration as a function of the electrical characteristic of the first gas sensor, wherein data from the second gas sensor is used to correct for baseline sensor drift of the first gas sensor, wherein the third temperature of the second gas sensor is equal to the first temperature, wherein the first gas sensor operates at two temperatures, and further comprising alternately controlling the temperature of the first gas sensor between a first temperature and a second temperature while the first gas sensor is exposed to the fluid environment, wherein the temperature of the first gas sensor remains at the first temperature over a first period of time, transitions from the first temperature to the second temperature over a second period of time, remains at the second temperature over a third period of time, and transitions from the second temperature to a third temperature over a fourth period of time; wherein the temperatures of the first gas sensor and the second gas sensor are staggered such that when the first gas sensor is in the first period of time or third period of time of the first gas sensor, the second gas sensor is in the second period of time or the fourth period of time of the second gas sensor.

16. A method of determining a target gas concentration of a target gas in a fluid environment, comprising:

(a) exposing a first gas sensor to the fluid environment, the first gas sensor having an electrical characteristic that varies as a function of the target gas concentration, and monitoring electrical characteristics of the first gas sensor;

(b) exposing a second gas sensor to the fluid environment, the second gas sensor having an electrical characteristic that varies as a function of the target gas concentration;

(c) alternately controlling the temperature of the second gas sensor between a first temperature and a second temperature while the second gas sensor is exposed to the fluid environment, wherein the temperature of the second gas sensor remains at the first temperature over a first period of time, transitions from the first temperature to the second temperature over a second period of time, remains at the second temperature over a third period of time, and transitions from the second temperature to a third temperature over a fourth period of time;

(d) monitoring the electrical characteristic of the second gas sensor during the second and fourth periods of time; and

(e) calculating the target gas concentration as a function of the electrical characteristic of the first gas sensor, wherein data from the second gas sensor is used to correct for baseline sensor drift of the first gas sensor, wherein the third temperature of the second gas sensor is equal to the first temperature, wherein the first gas sensor operates at two temperatures, and further comprising alternately controlling the temperature of the first gas sensor between a first temperature and a second temperature while the first gas sensor is exposed to the fluid environment, wherein the temperature of the first gas sensor remains at the first temperature over a first period of time, transitions from the first temperature to the second temperature over a second period of time, remains at the second temperature over a third period of time, and transitions from the second temperature to a third temperature over a fourth period of time; wherein the temperatures of the first gas sensor and the second gas sensor are staggered such that when the first gas sensor is in the first period of time or third period of time of the first gas sensor, the second gas sensor is in the second period of time or the fourth period of time of the second gas sensor, wherein the transition from the first temperature to the second temperature of the first gas sensor comprises a plurality of stepped increases of the temperature from the first temperature to the second temperature of the first gas sensor.

17. A method of determining a target gas concentration of a target gas in a fluid environment, comprising:

(a) exposing a first gas sensor to the fluid environment, the first gas sensor having an electrical characteristic that varies as a function of the target gas concentration, and monitoring electrical characteristics of the first gas sensor;

(b) exposing a second gas sensor to the fluid environment, the second gas sensor having an electrical characteristic that varies as a function of the target gas concentration;

(c) alternately controlling the temperature of the second gas sensor between a first temperature and a second temperature while the second gas sensor is exposed to the fluid environment, wherein the temperature of the second gas sensor remains at the first temperature over a first period of time, transitions from the first temperature to the second temperature over a second period of time, remains at the second temperature over a third period of time, and transitions from the second temperature to a third temperature over a fourth period of time;

(d) monitoring the electrical characteristic of the second gas sensor during the second and fourth periods of time;

(e) calculating the target gas concentration as a function of the electrical characteristic of the first gas sensor, wherein data from the second gas sensor is used to correct for baseline sensor drift of the first gas sensor, wherein the third temperature of the second gas sensor is equal to the first temperature, wherein the first gas sensor operates at two temperatures, and further comprising alternately controlling the temperature of the first gas sensor between a first temperature and a second temperature while the first gas sensor is exposed to the fluid environment, wherein the temperature of the first gas sensor remains at the first temperature over a first period of time, transitions from the first temperature to the second temperature over a second period of time, remains at the second temperature over a third period of time, and transitions from the second temperature to a third temperature over a fourth period of time; wherein the temperatures of the first gas sensor and the second gas sensor are staggered such that when the first gas sensor is in the first period of time or third period of time of the first gas sensor, the second gas sensor is in the second period of time or the fourth period of time of the second gas sensor, wherein the transition from the first temperature to the second temperature of the first gas sensor comprises a plurality of stepped increases of the temperature from the first temperature to the second temperature of the first gas sensor; and

(f) calculating the target gas concentration as a function of the electrical characteristics of the first gas sensor at each of the plurality of stepped increases of the temperature.

18. The method of claim 11 , wherein the transition from the first temperature to the second temperature of the second gas sensor comprises a plurality of stepped increases of the temperature from the first temperature to the second temperature.

19. A method of determining a target gas concentration of a target gas in a fluid environment, comprising:

(a) exposing a first gas sensor to the fluid environment, the first gas sensor having an electrical characteristic that varies as a function of the target gas concentration, and monitoring electrical characteristics of the first gas sensor;

(b) exposing a second gas sensor to the fluid environment, the second gas sensor having an electrical characteristic that varies as a function of the target gas concentration;

(c) alternately controlling the temperature of the second gas sensor between a first temperature and a second temperature while the second gas sensor is exposed to the fluid environment, wherein the temperature of the second gas sensor remains at the first temperature over a first period of time, transitions from the first temperature to the second temperature over a second period of time, remains at the second temperature over a third period of time, and transitions from the second temperature to a third temperature over a fourth period of time;

(d) monitoring the electrical characteristic of the second gas sensor during the second and fourth periods of time; and

(e) calculating the target gas concentration as a function of the electrical characteristic of the first gas sensor, wherein data from the second gas sensor is used to correct for baseline sensor drift of the first gas sensor, further comprising the step of:

(f) determining whether the first gas sensor and the second gas sensor each reach an equilibrium state,

(g) when the first gas sensor and the second gas sensor reach their respective equilibrium state, determining a prior time when the first gas sensor and the second gas sensor reached their respective equilibrium state, and

(h) if the prior time is greater than a predetermined time, then invalidating the electrical characteristics of the first gas sensor and the second gas sensor measured at the prior time.

20. The method of claim 19 , wherein the first gas sensor operates at a single temperature.

21. The method of claim 20 , wherein the second gas sensor is in a constant state of system response to a repeating thermal waveform.

22. A method of determining a target gas concentration of a target gas in a fluid environment, comprising:

(a) exposing a first gas sensor to the fluid environment, the first gas sensor having an electrical characteristic that varies as a function of the target gas concentration, and monitoring electrical characteristics of the first gas sensor;

(b) exposing a second gas sensor to the fluid environment, the second gas sensor having an electrical characteristic that varies as a function of the target gas concentration;

(c) alternately controlling the temperature of the second gas sensor between a first temperature and a second temperature while the second gas sensor is exposed to the fluid environment, wherein the temperature of the second gas sensor remains at the first temperature over a first period of time, transitions from the first temperature to the second temperature over a second period of time, remains at the second temperature over a third period of time, and transitions from the second temperature to a third temperature over a fourth period of time;

(d) monitoring the electrical characteristic of the second gas sensor during the second and fourth periods of time;

(f) determining whether the first gas sensor and the second gas sensor each reach an equilibrium state;

(g) when the first gas sensor and the second gas sensor reach their respective equilibrium state, determining a prior time when the first gas sensor and the second gas sensor reached their respective equilibrium state; and

(h) if the prior time is greater than a predetermined time, then invalidating the electrical characteristics of the first gas sensor and the second gas sensor measured at the prior time, wherein the first gas sensor operates at a single temperature, wherein the second gas sensor is in a constant state of system response to a repeating thermal waveform, wherein the first gas sensor reports to the second gas sensor, a change in a partial pressure of the target gas detected in the first gas sensor.

23. A method of determining a target gas concentration of a target gas in a fluid environment, comprising:

(a) exposing a first gas sensor to the fluid environment, the first gas sensor having an electrical characteristic that varies as a function of the target gas concentration, and monitoring electrical characteristics of the first gas sensor;

(b) exposing a second gas sensor to the fluid environment, the second gas sensor having an electrical characteristic that varies as a function of the target gas concentration;

(c) alternately controlling the temperature of the second gas sensor between a first temperature and a second temperature while the second gas sensor is exposed to the fluid environment, wherein the temperature of the second gas sensor remains at the first temperature over a first period of time, transitions from the first temperature to the second temperature over a second period of time, remains at the second temperature over a third period of time, and transitions from the second temperature to a third temperature over a fourth period of time;

(d) monitoring the electrical characteristic of the second gas sensor during the second and fourth periods of time;

(f) determining whether the first gas sensor and the second gas sensor each reach an equilibrium state;

(g) when the first gas sensor and the second gas sensor reach their respective equilibrium state, determining a prior time when the first gas sensor and the second gas sensor reached their respective equilibrium state;

(h) if the prior time is greater than a predetermined time, then invalidating the electrical characteristics of the first gas sensor and the second gas sensor measured at the prior time; and

(i) calculating the target gas concentration as a function of the electrical characteristic of the first gas sensor, wherein data from the second gas sensor is used to correct for baseline sensor drift of the first gas sensor, wherein the first gas sensor operates at two temperatures, and further comprising alternately controlling the temperature of the first gas sensor between a first temperature and a second temperature while the first gas sensor is exposed to the fluid environment, wherein the temperature of the first gas sensor remains at the first temperature over a first period of time, transitions from the first temperature to the second temperature over a second period of time, remains at the second temperature over a third period of time, and transitions from the second temperature to a third temperature over a fourth period of time; wherein the temperatures of the first gas sensor and the second gas sensor are staggered such that when the first gas sensor is in the first period of time or third period of time of the first gas sensor, the second gas sensor is in the second period of time or the fourth period of time of the second gas sensor.

24. A method of determining a target gas concentration of a target gas in a fluid environment, comprising:

(a) exposing a first gas sensor to the fluid environment, the first gas sensor having an electrical characteristic that varies as a function of the target gas concentration, and monitoring electrical characteristics of the first gas sensor;

(b) exposing a second gas sensor to the fluid environment, the second gas sensor having an electrical characteristic that varies as a function of the target gas concentration;

(c) alternately controlling the temperature of the second gas sensor between a first temperature and a second temperature while the second gas sensor is exposed to the fluid environment, wherein the temperature of the second gas sensor remains at the first temperature over a first period of time, transitions from the first temperature to the second temperature over a second period of time, remains at the second temperature over a third period of time, and transitions from the second temperature to a third temperature over a fourth period of time;

(d) monitoring the electrical characteristic of the second gas sensor during the second and fourth periods of time;

(e) determining whether the first gas sensor and the second gas sensor each reach an equilibrium state;

(f) when the first gas sensor and the second gas sensor reach their respective equilibrium state, determining a prior time when the first gas sensor and the second gas sensor reached their respective equilibrium state;

(h) if the prior time is greater than a predetermined time, then invalidating the electrical characteristics of the first gas sensor and the second gas sensor measured at the prior time;

(i) calculating the target gas concentration as a function of the electrical characteristic of the first gas sensor, wherein data from the second gas sensor is used to correct for baseline sensor drift of the first gas sensor, wherein the first gas sensor operates at two temperatures, and further comprising alternately controlling the temperature of the first gas sensor between a first temperature and a second temperature while the first gas sensor is exposed to the fluid environment, wherein the temperature of the first gas sensor remains at the first temperature over a first period of time, transitions from the first temperature to the second temperature over a second period of time, remains at the second temperature over a third period of time, and transitions from the second temperature to a third temperature over a fourth period of time; wherein the temperatures of the first gas sensor and the second gas sensor are staggered such that when the first gas sensor is in the first period of time or third period of time of the first gas sensor, the second gas sensor is in the second period of time or the fourth period of time of the second gas sensor, wherein the transition from the first temperature to the second temperature of the first gas sensor comprises a plurality of stepped increases of the temperature from the first temperature to the second temperature of the first gas sensor.

25. A method of determining a target gas concentration of a target gas in a fluid environment, comprising:

(a) exposing a first gas sensor to the fluid environment, the first gas sensor having an electrical characteristic that varies as a function of the target gas concentration, and monitoring electrical characteristics of the first gas sensor;

(b) exposing a second gas sensor to the fluid environment, the second gas sensor having an electrical characteristic that varies as a function of the target gas concentration;

(c) alternately controlling the temperature of the second gas sensor between a first temperature and a second temperature while the second gas sensor is exposed to the fluid environment, wherein the temperature of the second gas sensor remains at the first temperature over a first period of time, transitions from the first temperature to the second temperature over a second period of time, remains at the second temperature over a third period of time, and transitions from the second temperature to a third temperature over a fourth period of time;

(d) monitoring the electrical characteristic of the second gas sensor during the second and fourth periods of time;

(f) determining whether the first gas sensor and the second gas sensor each reach an equilibrium state;

(g) when the first gas sensor and the second gas sensor reach their respective equilibrium state, determining a prior time when the first gas sensor and the second gas sensor reached their respective equilibrium state;

(h) if the prior time is greater than a predetermined time, then invalidating the electrical characteristics of the first gas sensor and the second gas sensor measured at the prior time; and

(i) calculating the target gas concentration as a function of the electrical characteristic of the first gas sensor, wherein data from the second gas sensor is used to correct for baseline sensor drift of the first gas sensor, wherein the first gas sensor operates at two temperatures, and further comprising alternately controlling the temperature of the first gas sensor between a first temperature and a second temperature while the first gas sensor is exposed to the fluid environment, wherein the temperature of the first gas sensor remains at the first temperature over a first period of time, transitions from the first temperature to the second temperature over a second period of time, remains at the second temperature over a third period of time, and transitions from the second temperature to a third temperature over a fourth period of time, wherein the temperatures of the first gas sensor and the second gas sensor are staggered such that when the first gas sensor is in the first period of time or third period of time of the first gas sensor, the second gas sensor is in the second period of time or the fourth period of time of the second gas sensor, wherein the transition from the first temperature to the second temperature of the first gas sensor comprises a plurality of stepped increases of the temperature from the first temperature to the second temperature of the first gas sensor; and

(i) calculating the target gas concentration as a function of the electrical characteristics of the first gas sensor at each of the plurality of stepped increases of the temperature.

26. The method of claim 19 , wherein the transition from the first temperature to the second temperature of the second gas sensor comprises a plurality of stepped increases of the temperature from the first temperature to the second temperature.

Assignments (1)
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Oct 4, 2021
From: THOMAS, DYLAN; HOWARD, TIM
To: H2SCAN CORPORATION
Reel/Frame 057695/0322 →
Continuity (2)
Provisional Application 62830182 · Apr 5, 2019
Related Publication 20220187230A1 · Jun 16, 2022
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