Four Channel 6.5 kV, 65 A, 100 ns–100 µs Generator with Advanced Control of Pulse and Burst Protocols for Biomedical and Biotechnological Applications

Round 1

Reviewer 1 Report

Detailed comments attached. This manuscript provides valuable comments concerning a novel pulsed power architecture and warrants consideration for publication after addressing the attached comments. 

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

The article entitled "Four channel 6.5 kV, 65 A, 100 ns - 100 μs generator with advanced control of pulse and burst protocols for biomedical and biotechnological applications" by Kandratsyeu et. al. describes a high voltage modulator with flexible amplitude, pulse width, repetition rate, polarity, and timing. The described system additionally discusses the user interface and over current protection.

The design was interesting and would be useful if the stated operational parameters were actually achieved. One of the main issues with this paper is the statement of operational parameters and complete failure to achieve these parameters. There is no simulation results to provide where the stated capabilities come from. 

The power supply selected is drastically under powered for the desired operational parameters. This is clearly seen in Figure 7.

The impedance of the modulator is 100 Ω though most in vitro biological samples are 10 Ω and in vivo samples can vary depending on the water content and size.

The authors state that the biological loads are purely resistive which is incorrect. Pulses are applied between two electrodes for either in vivo or in vitro with the biological sample in between, which is the definition of a capacitor. 

The authors state that the delay in the current waveform in Figure 7 is due to measurement delays, however on this time scale the delay is most likely due to inductance in the circuit or in the load. If there was a delay due to the measurement setup this should have been addressed before submission.

The thermal effects due to the high current and long pulse duration should be acknowledged, as other researchers have presented studies on the thermal affects on biological samples. 

In addition to the issues listed above, major rework is required as it pertains to grammar and punctuation. Some examples are given below:

Line 14: Should read “Pulsed electric fields”

Line 19: The reviewer believes the authors meant capable not cable “The generator is cable…”

Line 24: To be consistent there should be a space between 5 and MHz

Line 42: There are many other references pertaining to unipolar electroporation, the authors should include these other works. The pulse parameters for effective electroporation vary depending on cell line used and associated cellular effects, i.e. intracellular organelles vs. cellular membrane.

Introduction, second paragraph: you list multiple references for various modulator parameters but there is not brief statement of what they were doing or how effective the results were. Each statement about a different set of modulator parameters should include the cell line and a brief statement of effectiveness.

Line 51: This sentence is punctuated incorrectly as there is a list in the middle of a sentence. Additionally, the original references for each modulator topology should be cited rather than a review paper.

Line 63: circuit should be plural, unnecessary commas

Line 69: The modulator is not capable of use in all electroporation applications due to the lower pulse width limit. Many studies have used 10 ns pulses at much higher voltage levels to achieve electroporation and calcium release by the mitochondria. The flexibility of the modulator presented is very wide however, this statement is incorrect and should be altered.

Last paragraph of Introduction is redundant

Section 2: command labels should be in italics or quotes

Line 104: this sentence is poorly worded

Line 129: “each stage must…triggered..”

First paragraph of 2.2 is very poorly worded.

Line 207: f should be in italics ,f ,

Section 2.4 first paragraph: poorly worded

Line 248: width not with

Line 258: space required between just and 20

Line 263: Overhead?

Line 306: Figure 7

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

This paper focuses a new electrical pulse generator, which offers great experimental flexibility: ultrashort pulses, high repetition frequency, arbitrary pulse generation and good current handling. The generator has high applicability in the context of electroporation. 

The operation principle is overviewed well. The output characteristics are also shown in detail and in an understandable manner. The circuit itself is not fundamentally novel, however, the high applicability of the generator and novelty in the field of electroporation are exceptional. Nevertheless there are some crucial remarks, which in my opinion should be addressed:

1) How does the generator operate with 1-10+ kOhm range loads? Is it capable to deliver the same pulses? What is the dependence of the pulse shape on the increase of impedance? These characteristics should be shown or discussed. The need for impedance matching should be overviewed. 

2) The short circuit protection module and its' operation principle should be reviewed in more detail, i.e. the position of the current loop, other elements.

3) Without the actual circuits, electronic elements/models, it is hard to understand how the dynamic characteristics were ensured (e.g. the short circuit model), or synchronized driving. It prevents repeatability. Authors show general concepts without explaining specific solutions and elements in the circuits, which make the generator unique. 

In my opinion it's an excellent device, which is novel in the field where it is applied. Nevertheless, the paper looks like a commercial advertisement now. It shows only general concepts, but the concepts themselves are not new - the implementation as a whole is. Therefore, in my opinion, more detail on crucial circuits should be provided to enable repeatability, which is fundamental for science. The data could be provided as supplementary or any other way.

 

 

 

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The article entitled "Four channel 6.5 kV, 65 A, 100 ns - 100 μs generator with advanced control of pulse and burst protocols for biomedical and biotechnological applications" by Kandratsyeu et. al. has been corrected and the additional information provided by the authors presents a much clearer story to the readers. There are a few minor edits that the reviewer believes would increase the clarity of the article.

Line 51: currently reads “ for vivo experiment treating” should read “ for in vivo…”

Line 299: currently reads “type or generator” it is believed it should read “type of generator”

Section 2: it would be helpful for the authors to ensure that any labels used for the modulator commands are in italics to differentiate them from standard text in the manuscript (this has been done in some instances).

The statement confining the pulse burst duration and repetition rate to 100 W average power provides the limitations of the modulator and clarifies the choice of power supplies selected for the modulator.

Overall, the corrections made to the manuscript are well done and greatly clarify the operation and functionality of the proposed modulator.

Author Response

Dear Reviewer

Authors thank your comments about the paper, which contributed to increase the interest of the paper to readers and the archival value of it. We tried to answer to all the comments.

The corrections were made and the English was checked.

 

Reviewer 3 Report

Authors in part addressed my comments. I don't have additional comments.

Nevertheless, I find the answer strange:

"However, they have not gone into too much detail about the electronic circuits, as this would lengthen the article too much, and make it cumbersome for the readers of this journal, as it would be outside the scope of it."

The paper does not focus applied research, but focuses the electronics, the working principle and the generator itself. Not providing the used electronics circuits in a 100% electronics paper describing the generator could be compared to not providing the type of cells and used reagents in a biological paper. Sounds strange. Authors can always use supplementary material if the length of the text is a concern. However, I have no doubts about the overall merit of the generator, so I leave the technical requirements for the Editors.

Author Response

Dear Reviewer

Authors thank your comments about the paper, which contributed to increase the interest of the paper to readers and the archival value of it. We tried to answer to all the comments.

No further comments and the English was checked.