Gas concentration detection by means of thermoacoustic sound wave

Patent metadata

Field	Value
Publication number	US-2022074897-A1
Application number	US-202117446507-A
Country	US
Kind code	A1
Filing date	Aug 31, 2021
Priority date	Sep 10, 2020
Publication date	Mar 10, 2022
Grant date	—

Abstract

A gas sensor having a heater, a receiver, and a space arranged between the heater and the receiver, is described, the heater being configured to generate a thermoacoustic sound wave propagating through the space by using a stimulation signal. The receiver is in this case configured to receive the thermoacoustic sound wave that has propagated through the space and to convert it into a reception signal that has a time-of-flight-dependent shift with respect to the stimulation signal and therefore information relating to the gas concentration in the space.

First claim

1 . A gas sensor comprising:
a heater, a receiver, and a space arranged between the heater and the receiver, the heater being configured to generate a thermoacoustic sound wave propagating through the space by using a stimulation signal, and the receiver being configured to receive the thermoacoustic sound wave that has propagated through the space and to convert the thermoacoustic sound wave into a reception signal that has a time-of-flight-dependent shift with respect to the stimulation signal and therefore information relating to the gas concentration in the space.

2 . The gas sensor as claimed in claim 1 , wherein the receiver comprises a microphone.

3 . The gas sensor as claimed in claim 1 , wherein the receiver comprises a temperature sensor.

4 . The gas sensor as claimed in claim 1 further comprising:
a gas concentration determination circuit that is configured to determine:
a phase shift between the reception signal and a heater signal, or
based on the reception signal, a time of flight of the thermoacoustic wave through the space, which are respectively a measure of the gas concentration in the space.

5 . The gas sensor as claimed in claim 4 , wherein the heater signal is the stimulation signal or a temperature signal that indicates a temperature of the heater.

6 . The gas sensor as claimed in claim 5 , wherein the electrical resistance of the heater is temperature-dependent, the gas sensor being configured to generate the temperature signal as a function of the electrical resistance of the heater.

7 . The gas sensor as claimed in claim 1 , which furthermore comprises a thermal conductivity determination circuit that is configured to determine the thermal conductivity of the space based on the heater signal.

8 . The gas sensor as claimed in claim 1 further comprising a driver circuit that is configured to apply the stimulation signal to the heater.

9 . The gas sensor as claimed in claim 1 , wherein at least the heater, the receiver, and the space arranged between the heater and the receiver, are integrated into a microsystem or a MEMS system.

10 . The gas sensor as claimed in claim 9 , wherein the microsystem or the MEMS system comprises a first terminal for application of the stimulation signal to the heater and a second terminal for output of the reception signal.

11 . The gas sensor as claimed in claim 9 , wherein the heater is arranged on a first side of a cavity in the microsystem or the MEMS system, and the receiver comprises a membrane that is arranged at a distance from the heater on a second side of the cavity in the microsystem or the MEMS system.

12 . A method for determining a gas concentration, comprising:
applying a stimulation signal to a heater to generate a thermoacoustic sound wave that propagates through a space arranged between the heater and a receiver, receiving the thermoacoustic sound wave at the receiver to generate a reception signal, determining a time-of-flight-dependent shift between a heater signal and the reception signal, and determining the gas concentration in the space based on the time-of-flight-dependent shift.

13 . The method as claimed in claim 12 , wherein the heater signal is a periodic signal and the determination of the time-of-flight-dependent shift comprises determining a phase shift between the reception signal and the heater signal.

14 . The method as claimed in claim 12 , wherein the determination of the time-of-flight-dependent shift comprises determining a time of flight of the thermoacoustic sound wave through the space.

15 . The method as claimed in claim 12 , wherein the heater signal is the stimulation signal that indicates a temperature of the heater or a temperature signal that indicates the temperature of the heater.

16 . The method as claimed in claim 15 , wherein the electrical resistance of the heater is temperature-dependent, and the temperature signal is generated as a function of the electrical resistance of the heater.

17 . The method as claimed in claim 12 , which furthermore comprises determining the thermal conductivity of the space based on the heater signal.

Assignees

• Infineon Technologies Ag

Inventors

• Eberl Matthias
• Jost Franz
• Kolb Stefan

Classifications

• G01N29/2431 Primary

  using other means for acoustic excitation, e.g. heat, microwaves, electron beams (sound producing devices not otherwise provided for G10K15/04) · CPC title

• G01N29/024 Primary

  by measuring propagation velocity or propagation time of acoustic waves · CPC title

• G01N2291/02809

  Concentration of a compound, e.g. measured by a surface mass change · CPC title

• G01N2291/015

  Attenuation, scattering · CPC title

• G01N29/4427

  with stored values, e.g. threshold values · CPC title