Terahertz Metamaterial Sensor for Sensitive Detection of Citrate Salt Solutions
, Qinnan Zhang 1, Dongxiong Ling 1, Dongfeng Liu 2 and Dongshan Wei 1,*
Round 1
Reviewer 1 Report
This is an experimental paper on the detection of citrate salts using terahertz metamaterials. It succeeds in distinguishing six different citrate salts based on differences in refractive index. The results are not surprising, but the paper is steady progress. We believe that the following points need improvement.
1. Poor discussion of the results. The frequency shift in Figure 8 is not consistent with the expected value from the sensitivity of the sensor shown in Figure 6(b) and the refractive index in Figure 9, although the order is correct. Why is this? A quantitative discussion on this point should be needed.
2. Is the incident light polarized? If so, what is its direction?
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
In this manuscript, a sensor is designed to detect Citrate Salt. The manuscript is well written and the topic is interesting. Please Consider the comments below.
1. The manuscript does not have a comparison table. It is better to add a table in which the results of the proposed structure are compared with similar previous articles.
2. New structures have been designed based on photonic crystals that have a higher quality factor. What is the advantage of the proposed work over them? For example, a number of these articles have suggested that it is better to refer to and add the advantage of the proposal to the text.
https://doi.org/10.1016/j.yofte.2019.03.009, https://doi.org/10.1016/j.optlastec.2021.107397, https://doi.org/10.1016/j.rinp.2020.103022, https://doi.org/10.21203/rs.3.rs-1459722/v1
https://doi.org/10.1016/j.ijleo.2020.165994, https://doi.org/10.3390/s130202566
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
In the manuscript entitled “Terahertz Metamaterial Sensor for Sensitive Detection of Cit-1 rate Salt Solutions” an asymmetric double-opening ring metamaterial sensor is designed, fabricated and used to detect citrate salts combined with THz spectroscopy.
Citrate salts (CSs) as one type of organic salts have been widely used in food and phamaceutical industries. Accurate and quantitative detection of CSs in food and medicine is very important for health and safety. Factors that influence the sensitivity of the metamaterial sensor including the opening positions and the arrangement of the metal opening ring unit, the refraction index and the thickness of the analyte deposited on the metamaterial sensor have been analyzed and discussed from electromagnetic simulations and THz spectroscopy measurements. Based on the high sensitivity of the metamaterial sensor to the refractive index of the analyte, six different citrate salt solutions with low concentrations were well identified. Therefore, THz spectroscopy combined with a metamaterials sensor can provide a new, rapid and accurate detection of citrate salts.
The numerical simulated results are in good agreement with the theoretical analysis.
The manuscript structure is generally well processed, but there are some details that need to be modified. The most important are:
1- The introduction part of the manuscript can be improved by referring to new and more significant references.
2- On what basis the initial design of the proposed structure, is presented?
3- What are the losses of the proposed structure?
4- Write the necessary steps and conditions for fabrication of the proposed sensor in the text of the manuscript.
5- If possible, please compare the specifications of the structure provided by yourself with the specifications of some suitable references provided in recent years and bring them in a suitable table.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
