Development of a Portable and Sensitive CO₂ Measurement Device with NDIR Sensor Clusters and Minimizing Water Vapor Impact

Round 1

Reviewer 1 Report

1.Consideration should be given to the fact that the measured carbon dioxide concentration also depends on atmospheric pressure.

2.A description of the microcomputer for the device is also needed.

3.What modifications are needed when temperatures are as low as 0 degrees Celsius or as high as 30 degrees Celsius or more?

4.CO2 sensor of electrochemistry method should be mentioned.

5.K30 data sheet is needed as a reference.

 

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

The work contributes a well method that can overcome individual sensor drift and irreproducibility by clustering of sensors. The regression analysis process is reasonable, and the corrected measurement results have a good agreement with Picarro.

However, this manuscript should solve the issues that listed below before it can be accepted.

1.      In section 2.3 of manuscript, please explain the meaning of “zero air”.

2.      The same section 2.3 of manuscript, the calibration curves are very close between 35% and 50% relative humidity, and the difference increases when increasing from 50% to 65%. This may indicate that the optimal RH condition for applying CO2 sensors is about 50%. There seems to be insufficient cause-and-effect relationship between the preceding and following text here, please explain.

3.      Please explain the meaning of each variable in Eq 1.

4.      In section 3.3, The measurement results of the last 3 days, the agreement between the corrected values of some NDIR sensors and Picarro’s measurements has decreased compared to the previous four days, please give the available measurement time for this correction method.

5.      Please change to a higher resolution image, for example, Figure1, the part of sensors is not very clear. Other images can be saved in a higher resolution format and replaced one by one. Or it could just be that the resolution of the picture in the PDF file I received was not high.

Author Response

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Reviewer 3 Report

A good paper - some minor improvements are needed to the English.

I note the extensive discussion of the effect of humidity but see no discussion of the possible interference from other pollutants, particularly those which night have signals in the relevant bands.  While i think this is only minor I would like to see it clearly stated and have assurance that such interferences have been assessed and can be dismissed

Author Response

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Reviewer 4 Report

I don't find any novelty in this work. The introduction is very weak and limited. I don't find any comparisons and limitations of earlier techniques. 
Many parts of the intro are copied from:

1. Chamberless NDIR CO2 Sensor Robust against Environmental Fluctuations

   Mostafa Vafaei and Amir Amini

   ACS Sensors 2021 6 (4), 1536-1542

   DOI: 10.1021/acssensors.0c01863

 

The experimental setup's actual image should be added.

Explain the process flow of the experimental setup and how it was carried out

A table with all the settings of the devices and values should be summarized. 

Finally, the designed setup should be benchmarked with the recent state of the art. 

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 4 Report

Authors have thoroughly improved the article. All the suggested changes have been made. Good work