(cantilever) gas sensor with MOS technology - How does it work?

[lufer17]

Hello everyone, I'm having trouble understanding how the gas sensor with MOS technology works. I cannot find a study material with the basic principles of operation. I can find some subjects, but with information such as too deep knowledge, I have no in-depth knowledge on the subject.
Could someone please explain give me a link, document (PDF) that talks about this subject in a fundamental way how it works?

 

[d123]

Hi,

Try searching for MOS gas sensor working principle.


Learn about Gas Sensors by Animation

Operating principle

Metal Oxide Gas Sensing Material and MEMS Process

Hope that's what you meant.

 

[lufer17]

Hi,

Try searching for MOS gas sensor working principle.


Learn about Gas Sensors by Animation

Operating principle

Metal Oxide Gas Sensing Material and MEMS Process

Hope that's what you meant.

Thank you, I found some animations, before posting my question here, but as I heard, I am not English and it is very difficult. I needed a text to better understand how it works (example: book).


will tell you what I understand. when we have the resonant cavities in the case of this cantilever device, when there is a molecule on the surface of this device, it will respond at a certain frequency. That way we will know what substance is on the surface of the device. Because it will vibrate at that frequency x. My problem is: I cannot understand this relationship with the mosfet when we deal with gas sensors, I cannot understand the basic principle associated with the mosfet device (attention I know how the mosfet works). I can't find a simple relationship about understanding (explanation of the subject)

 

[d123]

Hi,

Probably not adding to anything... It apparently compares gas resistance to oxygen resistance on surface, which affects a voltage divider, that is compared to a reference voltage. It's sort of a Wheatstone Bridge, I suppose. Would the frequency change be like changing the resistor in an RC network? MOSFETS have a lot of capacitance on every side, maybe or maybe not that is part of functioning. Pardon my ignorance and guessing things.

 

[FvM]

The silicon MEMS sensor described in post #1 has nothing to do with the metal oxixyde semiconductor sensors addressed in the post #2 links. The MOS sensor element doesn't even use SiO2 but semiconducting SnO2 or similar material.

The last link discusses MOS sensors carried by a silicon MEMS structure.

You really need to look sharp what's the specific sensor mechanism and how it's implemented. The post #1 sensor seems to measure the adsorption on or the absorption of a substance in a sensor layer by its mass increase, indicated by the mechanical resonance frequency.

 

[d123]

Hi FvM,

The silicon MEMS sensor described in post #1 has nothing to do with the metal oxixyde semiconductor sensors addressed in the post #2 links. The MOS sensor element doesn't even use SiO2 but semiconducting SnO2 or similar material.

The last link discusses MOS sensors carried by a silicon MEMS structure.

You really need to look sharp what's the specific sensor mechanism and how it's implemented. The post #1 sensor seems to measure the adsorption on or the absorption of a substance in a sensor layer by its mass increase, indicated by the mechanical resonance frequency.

Thanks for pointing out my mistake.

My apologies to lufer17 for not noticing the difference.