In the chemo-resistive gas sensors, it has been observed that some semiconducting oxides are showing a very good response at high temperature, towards a particular gas but it is also showing a partially good response towards more other two or three gases simultaneously. Now, this tendency is disastrous if anyone wants to commercialize the sensor devices. Therefore, how anyone can carefully design the active materials, manipulating by the precise selection of the dopping element, so that good selectivity at low-temperature sensing material can be synthesized.
Bochenkov, V.E. and Sergeev, G.B., 2010. Sensitivity, selectivity, and stability of gas-sensitive metal-oxide nanostructures. Metal oxide nanostructures and their applications, 3, pp.31-52.
High selectivity for MOS gas sensors is still challenging. Following answers as well.
Hi Debmallya,
That's a good question! That's the hard part of using chemo-resistive gas sensors, I believe. You can try the following to see if they can solve the problem:
1. What gases, in what concentration, are present in the sample?
Your sensor might be sensitive to another gas, but maybe that gas is not present in high concentration in the real samples you want to test. For example, if you are designing a gas sensor for an environment with a maximum of 10 ppm NH3, and your sensor is sensitive to 100 ppm NH3 but shows an insignificant response to 10 ppm NH3, you will not have cross-sensitivity to NH3 "at that environment".
2. Changing the sensing layer: There might be some papers on a material that is more selective to the target gas you're working on.
I think for metal oxide , whenever you can increase the roughness of your metal oxide you can get what you want
Dear Debmallya Das,
the low selectivity of gas sensors based on Semiconducting Metal Oxides (SMOX) is the major problem, which with some exceptions will be found for most analyte gases. Yes, tuning the material properties of SMOX by additives is one way to partially overcome this problem, namely to change the selectivity. Still, additives do not result in a specific response to only one analyte. There are additional possibilities like filters, that can be used to get a more selective response.
Another other approach is using an array of different gas sensors - either actual different sensors (differently doped/loaded SMOX) or operating a sensor at different temperatures. The sensor array will provide a certain pattern of a certain analyte mixture; using chemometrics/patter recognition, one can analyse this pattern and identify and quantify a certain gas.
Best regards,
David Degler
- Badges
- Science topic
- Similar topics
- Linguistics
- Composition Studies
- Publication