What Is the Optimal Method for Cleaning Screen-Printed Electrodes?

Round 1

Reviewer 1 Report

1. In the part of material and methods, the author should add some subheadings and rearrange this part with clear descriptions.
2. Line 181, why did author use the gold and platinum as electrodes?
3. Line 191, why were the scanning rate of 100 mV/s and the potential range from -0.200 V to 0.600 V selected?
4. The figures and tables are not in good format, the author should rearrange these figures and tables.
5. In the part of results, there were little discussions and lacks of comparisons with other investigations.
6. The results of SEM and EDX should be placed before the introduction of the CV testing.

Author Response

Dear Reviewer,

We would like to thank you for taking the time to evaluate our work and for all your valuable observations, which we believe helped improve the overall quality of the manuscript. Please find our answers to all the comments in the attached document.

Author Response File: Author Response.docx

Reviewer 2 Report

The authors show different methods to clean screen-printed electrodes of gold or platinum and quantify the effect of the cleaning by data taken from CV and EIS measurements.

 

General remarks:

Unfortunately, the manuscript is written in a very confusing way as descriptions of the experiments and statements on results or general findings are mixed up and not clearly separated. The methods part is lacking a lot of information, the results are mixed up with discussions, and the discussion part is very poor and missing a lot of necessary considerations. In addition, there are a lot of small (grammar) errors and flaws in the manuscript. I tried to find them, marked them in the PDF of the manuscript or gave a comment in the following. All in all, I am disappointed, that the time and work of the reviewer is needed here, where ten (!) authors could have done a comprehensive writing and proof reading.

Remarks regarding special passages in the text:

Abstract: The mentioned values for Rp are confusing, as they are sometimes the difference between before and after treatment and sometimes absolute values. I think it would be easier for the reader, if a reduction of Rp (the difference between treated and untreated) would be given in %?

Line 24: Rp is mentioned here for the first time and should be explained here and not in line 30.

Introduction: For the statements from line 36 till 57 not a single reference is given. There should be at least one reference per statement or mentioned application.

Introduction: Your article focuses on cleaning of SPEs, but you did not give the state of the art regarding cleaning. This is a serious flaw.

Line 61: I assume “by” should be replaced by a “thus” or “such”?

Line 65: WE, RE and CE are mentioned here for the first time and thus should be explained.

Line 69: To which electrodes do the “these electrodes” refer to? WE, RE, CE or all kinds of electrodes?

Figure 1: The fonts in the labels are written in the same color as their background and thus cannot be read very well. Please select a darker color or black for the fonts of the labeling.

Line 90: “Drying can be done in an oven at room temperature…” I assume it should be “above” and not “at” room temperature? And there are a lot more drying/sintering methods than the use of an oven or UV light.

Figure 2 could be integrated in Figure 1 as part b) and in addition there should be labels marking which part of the electrodes is made of which material in the three examples.

Line 102: “…improve the viscosity OF THE INK FOR the printing process”

Line 106: There is a reference to figure 2 regarding gold as electrode material. But there is no help for the understanding of this information found in figure 2. I assume that the reference can be deleted.

Line 111: “…from the ink”: I assume that organic impurities have to be removed from the printed electrodes and not from the ink.

Line 113-115: There should be at least one reference for this sentence, as it is very important for the motivation of your paper.

Line 120: What is “working electrode substrate”? There is a substrate to be printed on and a WE. But not a “working electrode substrate“.

Line 140: The SPEs can be deposited. But they are not “disposable” in a way of being eco-friendly or recyclable, as this “disposable” implies. Everything is disposable as far as the amounts/concentrations are low, or a recycling is not economic. But Pt, Au or Ag should be recycled and by writing “disposable” you are stating, that this is not the case. In addition, the SPEs are a laminated system of different materials, which makes it even more complicated to recycle them. You should at least write “can be disposed” and perhaps should mention the problems.

Materials and Methods: In the introduction part you use the term “ink” and here you start to use “paste”. You should be consistent with the wording and explain both at the beginning of your manuscript.

Line 147: Can you give an article number for the used SPEs or more detailed information? In the Author Contributions you state that M.G. manufactured the gold SPEs. So you should be able to write more about it. In terms of reproducibility and general usability of your work, this is very important.

Line 149: “ZRA GAMRY INSTRUMENTS“ is not a machine. I assume it should be “interface 1010E from GAMRY INSTRUMENTS”?

Line 158: Give purity grades of the chemicals or exact article numbers, as this could be crucial for your results.

Line 171: You mention literature but you don’t refer to it. You should present a passage or a table giving an overview on the literature and your comments on the individual references. This could be placed here or in the introduction.

Line 180: You should state that this is done for degreasing, as this is just mentioned later in the text along the way.

Line 182-184: You did not state, if you removed the solvents afterwards or cleaned the SPEs by e.g. rinsing them with water? And I strongly assume that 1 µl of acetone will be evaporated faster than in 10 minutes.

Figure 4 and others: Please make plots of your measurement and not just paste a screenshot from the software used for the measurement. The fonts should be of the same size in all figures and not as small as in the lower plot of figure 4. Don’t give useless positions after decimal points such as 40.00 µA. You label the axis with abbreviations (Im and Vf) which are not explained in the text or the figures caption and m and f should be lower cases. In addition, there are several cases where the labels interfere with each other.

Figure 4: The figure's caption explains the blue and purple curves but not the red and green. I assume these are part of blue and purple, respectively, and this is another reason for doing an appropriate plot of your measurement data?

Line 200: “…which confirms the necessity and efficiency of the degreasing stage FOR PLATINUM ELECTRODES by removing…”

Table 1: You give absolute values for Im and Vf, but explained only for Im where you got them from.

Line 216 to 218: The information about the measurement procedure should be placed in the caption of figure 5 or the text before figure 5. In addition, table 2 does not show the EIS measurements, it shows results extracted from the measurements. This passage is confusing.

Table 2: In the caption you mention “constant transfer resistance Rct” but in the table itself you give Rp?

Line 224 to 227: I assume that this passage is misplaced, as it is located between the results and the short discussion regarding the difference between results from gold and platinum electrodes? Or is it a part of this discussion, then it should be in the same passage and not separated by a line break?

Line 233: Ethanol in the whole manuscript, but here you start to use “ethyl alcohol” in parallel. Please use a consistent wording.

Line 246 to 248: Same as in line 216 to 218

Table 4 and following: I disagree with using the exponent notation using E+x instead of 10^x. In addition, e.g. “3.09 E+3” could be written and read faster as 3090.

Line 260: Please give the exact composition of the H2O2 PBS solution.

Line 264-266: Is this a finding of your experiments? Then state this after the respective experiment. If this is a general statement made before setting up the experiment, state this and give a reference.

Line 269: After doing the CV in H2O2 / PBS solution, how did you clean the electrodes? Just letting the residual solution drip off or did you clean or dry the electrodes in a special way?

Line 287 “gold/platinum” should be “gold or platinum”?

Line 307: You state that a difference of 1 µA is an improvement. How reproducible are your measurements that you can be sure 1 µA is significant and not just a fluctuation?

Line 310 to 312: Give a reference for that statement.

Table 7 to 10 and Figure 11 to 12: The results for gold and platinum electrodes should be shown in merged tables and figures a done beforehand for the other cleaning methods.

Figure 13 and 14: The scale bars and their captions are too small to be read.

Line 390 to 392: I cannot follow that statement, as you don’t know which kind of contaminant you have on the two different electrode materials, and thus you cannot distinguish your results between electrode material or type of contaminant. Perhaps you can state this after EDX, but this was not done at this point.

Line 399: You don’t show data regarding this. You should show or delete this sentence.

Table 11: You should explain the different abbreviations like “Net int” or “Kratio” and Z, R, A and F used in the columns of the table. What are the essential numbers you need from table 11? I assume the weight %? You should reduce the data given to the data required for your explanation. All other data could be shown as supplemental material. Right now the table shows too many numbers and the reader doesn’t know on which he should focus.

I do not agree with your results taken from the EDX measurements as you do not show data regarding the addition of Na, Cd and Fe and the given weight % data for Au lets me assume, that the untreated electrode is the best as there is the highest amount of gold present. In addition, you do not show data for platinum but in different parts of the paper beforehand you talk about the different amount of contaminant on gold and platinum and you use this to support your findings in CV and EIS measurements. Even in the conclusion, you talk about contamination, but you do not measure them. All in all you should only talk of an effect of your treatment, you even don’t show that it is a cleaning as the measurements supporting this are missing.

Line 410 to 415: It is not reasonable that a solvent such as acetone removes platinum and your other methods do not remove the platinum. You yourselves  write in line 291 regarding the CV that “Increasing the number of cycles can lead to electrode damage”.

Discussion: Most of the information from literature should be placed in the introduction, and here just a short reference should be made. The discussion from line 436 on has nothing to do with your work as you did not investigate all these things and you are not able to give a comparison.

Line 428: You give an absolute value of reduction of Rp and the reference gives a factor. How should the reader be able to judge the difference?

Line 434: Literature gives Rct and you Rp, but you never explained the difference. How should the reader be able to compare this?

Discussion: All in all, the discussion part is very poor. You do a comparison with two reference values from literature. But:

1: You do not discuss the reliability or reasonability of your own findings.

2: You do not compare the different cleaning methods you used with each other and for different applications regarding their particular effort and hence efficiency. Give a short discussion of obtained improvement by the different cleaning methods vs. the amount of work or time needed for the cleaning. Thus, the reader could learn about the efficiency of the different methods and compare them.

3: You do not discuss, that the cleaning with polar solvent was done at a certain spot of the working electrode whereas H2O2 solution in CV treated the whole device including the reference and counter electrodes. What is the influence of including them into the treatment compared to the cleaning of only the working electrodes?

4: Throughout the paper you have small passages discussing your findings, often based on talking about contamination or roughness. You should move these to the conclusion part, line them up in an ordered way and clearly show, which of your findings or references from literature support them.

 

Comments for author File: Comments.pdf

Author Response

Dear Reviewer,

We would like to thank you for taking the time to evaluate our work and for all your valuable observations, which we believe helped improve the overall quality of the manuscript. Please find our answers to all the comments in the attached document.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Suggest the article be accepted.

Reviewer 2 Report

I thank you for your work. Your methods, findings and conclusions are more reasonable and traceable now.