Photoacoustic gas sensor and pressure sensor

Patent metadata

Field	Value
Publication number	US-11519848-B2
Application number	US-202016905295-A
Country	US
Kind code	B2
Filing date	Jun 18, 2020
Priority date	Jun 19, 2019
Publication date	Dec 6, 2022
Grant date	Dec 6, 2022

Abstract

A MEMS photoacoustic gas sensor includes a first membrane and a second membrane opposing the first membrane and spaced apart from the first membrane by a sensing volume. The MEMS photoacoustic gas sensor includes an electromagnetic source and communication with the sensing volume to deflect the first membrane and the second membrane.

First claim

What is claimed is:

1. A MEMS photoacoustic gas sensor, comprising:
a housing enclosing:
a first membrane;
a second membrane opposing the first membrane and spaced apart from the first membrane by a sensing volume; and
an electromagnetic source in communication with the sensing volume,
wherein the first membrane is supported by a semiconductor substrate having an opening through the housing, the first membrane overlying the opening, wherein the electromagnetic source is supported by the semiconductor substrate, and wherein the electromagnetic source is an infrared source comprising a heater, and
wherein the first membrane is disposed between the sensing volume and a first volume, and the second membrane is disposed between the sensing volume and a third volume, wherein the first volume is a front volume and the third volume is a back volume; or wherein the first volume is a back volume and the third volume is a front volume, wherein a first stiffness of the first membrane and a second stiffness of the second membrane are selected such that an acoustic signal travelling from the front volume through the sensing volume to the back volume leads to a same magnitude of deflection of the first membrane and the second membrane within a tolerance range, and wherein the first stiffness is different than the second stiffness.

2. The sensor according to claim 1 , wherein the first membrane includes at least one first opening fluidly coupling the first volume and the sensing volume, and the second membrane includes at least one second opening fluidly coupling the third volume and the sensing volume.

3. The sensor of claim 2 , wherein the at least one first opening and the at least one second opening are differently sized.

4. The sensor according to claim 1 , further comprising a backplate disposed between and spaced apart from the first membrane and the second membrane.

5. The sensor according to claim 1 , further comprising one or more connectors mechanically coupled between the first membrane and the second membrane.

6. The sensor of claim 5 , wherein the one or more connectors are electrically conductive.

7. The sensor of claim 5 , wherein the one or more connectors are electrically insulating.

8. The sensor according to claim 5 , wherein the one or more connectors divide the sensing volume into a plurality of partial sensing volumes, the electromagnetic source configured to cause alternating bowings of the first membrane and the second membrane in adjacent partial sensing volumes.

9. The sensor according to claim 1 , wherein the sensing volume is a first sensing volume, wherein the sensor comprises at least a third membrane forming at least a part of a stack with the first membrane and the second membrane and defining a second sensing volume in the stack.

10. The sensor according to claim 1 , further comprising a circuit configured to process at least one signal generated by a first deflection of the first membrane and a second deflection of the second membrane.

11. A MEMS pressure sensor, comprising:
the sensor according to claim i; and
a circuit configured to measure a capacitance between the first membrane and the second membrane.

12. The sensor according to claim 1 , wherein the tolerance range is ± 5 %.

Assignees

• Infineon Technologies Ag

Inventors

• Manz Johannes
• Glacer Christoph
• Tumpold David

Classifications

• G01L23/12

  by changing capacitance or inductance · CPC title

• G01N29/2425

  optoacoustic fluid cells therefor · CPC title

• G01N2021/1704

  in gases · CPC title

• G01L19/0092

  Pressure sensor associated with other sensors, e.g. for measuring acceleration or temperature (G01L9/025, G01L9/045, G01L9/065, G01L9/085, G01L9/105, G01L9/125, G01L19/02, G01L19/04 take precedence; measuring two or more variable G01D21/02; temperature sensors with pressure compensation G01K1/26) · CPC title

• G01L9/0073

  using a semiconductive diaphragm · CPC title