Optimizing Piezoelectric Cantilever Design for Electronic Nose Applications

Round 1

Reviewer 1 Report

1. The optimization method is questionable. The optimization of length and width is carried out separately, and the joint optimization problem is not considered.

2. As an academic paper, the theory of optimization method is insufficient.

3. There are many repetitions in the manuscript, such as “Line75-Line91“ and “Line92-Line108”.

4. There are some problems in the structure of the whole manuscript. Section 2 is "result and discussion", and the section 3 is "method", which does not conform to the general structure of scientific papers.

5. English needs to be improved.

Author Response

Reply to Reviewer 1:

Please see the attachment or you can find the response below 

We thank Reviewer 1 for the thorough and valuable comments and suggestions. Please find our detailed answers to the points below: 

Ad 1.) We appreciate this valuable comment. Consequently, we included the used numerical optimization technique in the methodology section, (Line 50-Line 71). Specifically, we optimized the geometric cantilever parameters (such as length, width and thickness) simultaneously by the bound optimization by quadratic approximation (BOBYQA) algorithm. A reference is also added for the optimization algorithm (reference 26). The result of the optimization section can be found from Line 159-Line 170 and Table 3.

Ad 2.) We agree with the reviewer comment and consequently added a brief theoretical background to our methodology section from Line 50-Line 68 (see also point Ad 1.)).

Ad 3.) We removed the mentioned repetitions in the updated manuscript version.

Ad 4.) We re-structured the manuscript according to this valuable comment: Section 2 is “Methods” and Section 3 is “Results and discussion”. In that line, we also moved the description of mesh and the cantilever (originally Line41 to Line55) to Section 2 (“Methods”).

Ad 5.) We thoroughly went through the document and improved the English language to our best knowledge.  

Author Response File: Author Response.pdf

Reviewer 2 Report

In the presented work, the Authors have proposed a study for the development of a biosensor on a very interesting application of food safety. The submitted paper, in particular, proposes a well done study for the optimization of the transducer using Finite Element Method simulations, enhancing a series of already published works with which the Authors have demonstrated the importance of cadaverine as biomarker for meet ageing and the necessity to have a stand-alone systems for the detection.

The simulations are well organized and clearly explained. The assumptions and the conclusions about the optimization of the geometry of cantilever described are well supported by the reported data and graphs.

However some important details are missing and some clarification and small correction in the text are needed.

• In Table 2 “KH” is not the correct measure unit (kHz).
• In Table 2 is not clear, in relation of the resonant frequencies reported for each metal, which is the used piezoelectric material and vice versa. The Authors should clarify these data.
• Probably due to an editing error the text from row 92 to 108 is two times repeated.
• There aren’t any details about the fabrication of cantilevers. It is a significant activity that deserves more importance. The Authors should insert some information about the fabrication processes or some reference.
• In row 142 “kΩ” is not the correct measure unit (kHz).
• In order to “demonstrate the high sensitivity” of the biosensors (row 143), the Authors should have calculate the sensitivity from the calibration curve and report the data. Some information about these important details is missing. Alternatively, it is necessary to better explain the concept of sensitivity expected from this type of biosensor, since tests with known cadaverine levels have not yet been carried out.

Author Response

Reply to reviewer 2:

Please see the attachment or you can also see the response below.

We are happy for the positive feedback and the corrections pointed out from Reviewer 2. Please find the answer to the review below.

• We agree with the feedback and clarified the missing information in Table 2 through Line 121- Line 123.
• We have gone through the manuscript and removed the named repetitions.
• We have also added further information about the fabrication process in the (restructured) “Methods” section (Line 85 -Line 95)
• We appreciate the comment on the errors and corrected the measured units (from KH to kHz in Table 2, and from kOhm to kHz in Line 187)
• In Line 188, we now point to our previous work (reference 25), where we discuss more details about the sensitivity of these measurements. We also added Figure 11 to show measurements on the cantilever beam when a mass is added.

Author Response File: Author Response.pdf

Reviewer 3 Report

Similar sensors using cantilevers were developed but this publication focuses on optimization for high sensitivity. The results are promising and meaningful. 

hence I suggest the paper can be accepted for publication after minor amendment is made.

(1) minor language/spell check required.  such as (46)  both for bottom and top electrode(s). 

(2) Figure 10:  the readers want to see a clear, magnified photo of fabricated cantilever, as well as the driving circuit or diagram.  

 --------- End of comments ---------

Thanks & regards 

Author Response

Reply to reviewer 3:

Please see the attachment or you can also find the response below. 

We appreciate the positive feedback for our paper and please find the answers for the points raised below.

Ad 1.)  We appreciate the point on typos. We have gone through the manuscript and corrected the mentioned and other typos, including the one in Line 77.

Ad 2.)  Figure 10 is magnified as per the reviewer comment.

Ad 3.)  We agree with the comment about the circuit diagram. The details about the custom drive circuit and the device is described in our previous paper (reference 27). In this manuscript, we referred the paper about the details in Line 177.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The paper has improved a lot from the previous one, and it is acceptable.