Dopamine-Sensing Characteristics and Mechanism by Using N2/O2 Annealing in Pt/Ti/n-Si Structure
Round 1
Reviewer 1 Report
The manuscript describes the preparation of MEMS structure sensor based on Pt as sensing element treated at various annealing conditions.
Although authors took great effort through the application of various sofisticated techniques in order to produce sensor structure, the manuscript suffers from a lack of simplicity of presentation and discussion of results. Also, the control experiment is missing.
The abstract contains irrelevant data (lines 14-22).
Section 2.2 is unnecessary since all relevant data is presented in Table 1.
Presented results in Figures lack clearness. For example, thick labels at the y-axis have values presented such as 100.0n or 10 micro. Most appropriate should be that labels contain these values. Also, the applied voltage is not comparable with other articles based on the electrochemical method, since the authors did not present voltage versus common reference electrode. Thus it is difficult to compare potentials, in order to get insight into possible side reactions.
Characterization of pH dependence is poorly done (only three pH values, mostly in low acid and alkali media). The criterion for this is not explained.
Also, the chemical equation that will describe the mechanism is missing. This is especially important since authors claim that dopamine autooxidaze to hydrogen peroxide (line 325)?!
Statement in line 334 is very debatable, since no relevant data concerning potential vs. reference electrode.
Electrochemical results are poorly explained and from an electrochemical point of view do not bring any relevant information. For example: scan-rate investigation.
Authors need to consult experts in electrochemistry, chemistry in order to design experiments appropriate to the presentation of the sensor-related investigation.
Overall, it is such a pity that this interesting approach to the development of the dopamine sensor did not realized its full potential in electrochemical measurements.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
1. This study is the follow-up work of Ref 27. Many sentences should be refined and significantly shortened.
2. Section 2.1
RCA is a standard cleaning method. The details could be shortened. Line 75 to Line 80 is not really necessary.
3. Section 2.2
Table 1 should be addressed here.
Figure 1 is similar to Ref 27, could put a reference here
4. Section 2.3
I assume the SU8 thickness is not important. The litho process is just to create the opening area for sensing. If so, this design concept could be addressed in this paragraph.
5. Figure 4
The scan rate figures for N52 are too cluttered. Please provide zoom-in view for both oxidation and reduction peaks. Same as the the later figures in the paper.
c & d why different concentration 1 um and 1 mM. Although the reason was addressed in the later part, 1st time readers might get confused here.
6. Line 327
327 The change in current value in case of dopamine with respect to pH7 solutions is more for N52 sensors.
could be rephrased as below
"The current value of N52 sensors shows clearer change between dopamine and pH7 solutions than O75 sensors."
7. Line302 should be figure b&d
Line 303 should be figure a&c
8. Line 371
why happened at 10 mV/s? no clear explanation
9. Line 373-374
Figure 6 d
the current stay lower from 10mV/s to 50mV/s, not a drastic drop. the statement at line 373 and 374 is doubtful.
Author Response
Please find the attached file.
Author Response File: Author Response.pdf
Reviewer 3 Report
In this paper the authors demonstrate sensing capability of thickness optimized and annealed Pt membrane in MEMS structure with a low dopamine concentration of 1 pM with a small volume of 10 μL. The authors utilised annealing temperatures ranging from 500 to 700oC in N2 and O2 ambient. Using optimised nitrogenated thin Pt membrane in N2 ambient at a lower scan rate of 50 mV/s, 1 pM dopamine was detected. The pH and dopamine sensing mechanisms are discussed to be attributed to Schottky barrier height modulation in contact of pH/dopamine. The sensing performance of the sensors is optimized and a stable time response is also obtained. This is a nice work. The conclusion is supported by data. I think this manuscript is suitable for publication in current journal. I encourage the authors to incorporate more discussions on the advantages and disadvantages of using Pt/Ti/n-Si structure annealed in N2/O2 for dopamine sensing. In addition the motivation of the work should be clearly highlighted in the introduction section
Author Response
Please find the attached file.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Comments are addressed. However, This is still a follow up work of Ref. 27. Even though, a adhesion layer was added, the work shows high similarity to the previous work.
Author Response
Comments are addressed. However, This is still a follow up work of Ref. 27. Even though, a adhesion layer was added, the work shows high similarity to the previous work.
Authors' response: We appreciate your valuable time to review our paper. According to your suggestion, we have added our previous work reference [27] in the caption of Fig. 1. We have tried our best to modify fluent English in the revised manuscript. Thank you very very much for your acceptance.
