Design, Fabrication, and Evaluation of 3D Biopotential Electrodes and Intelligent Garment System for Sports Monitoring
Round 1
Reviewer 1 Report (New Reviewer)
Comments and Suggestions for Authors(1) This study explores the potential application of smart clothing that can measure the wearer’s ECG and EMG in real-time by wearing garments equipped with low-resistance electrodes made of silver-plated nylon yarn. To do so, the accuracy of these conductive knitted electrodes in measuring ECG and EMG must first be confirmed. For this purpose, it is necessary to compare the results with those obtained from widely used Ag/AgCl gel electrodes in hospitals, but such experimental data is not available. Therefore, the experimental results used in reference (34) cited by the authors are essential.
(2) The ECG signal pattern shown in Figure 16 of this paper is entirely different from the typical ECG signals measured using Ag/AgCl gel electrodes. Compare it with Figure 7 in reference (34).
(3) The EMG signal pattern shown in Figure 17(a) of this paper is also entirely different from the typical EMG signals measured using Ag/AgCl gel electrodes. There is no explanation of what an EMG value is or how it was obtained. Compare it with Figure 8(a) in reference (34).
(4) The paper states that muscle fatigue can be assessed by the fluctuation pattern of the EMG signal shown in Figure 17(a), but this is not understandable. It also mentions that muscle fatigue is determined by the frequency spectrum obtained from FFT of the EMG signal shown in Figure 17(a), but there is no citation provided. Here too, a comparative analysis with experimental results obtained using standard Ag/AgCl gel electrodes is necessary.
In conclusion, the paper cannot be approved for publication in its current state and must undergo a major revision for re-evaluation.
Comments on the Quality of English LanguageNo further suggestions..
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report (New Reviewer)
Comments and Suggestions for AuthorsThe authors reported the design, fabrication, and evaluation of 3D biopotential electrodes and intelligent garment system for sport monitoring. Although being interesting, I find that there are some major issues with the paper that require addressing prior to this being considered for publication in this journal. I have identified the main points for consideration below:
1. This manuscript has some spelling typos, style errors and grammatical errors. Please carefully check the whole manuscript.
2. In the introduction section, semi-dry electrodes as a representative biopotential electrodes are missing. So, I advise the authors add the introduction of semi-dry electrodes. In addition, some recent references related to semi-dry electrodes are recommended to be cited, such as SmartMat, 2024, 5, e1173; J. Neural Eng. 20 (2023) 026017; J. Neural Eng. 18 (2021) 046016; J. Neural Eng. 17 (2020) 051004.
3.The electrode-skin impedance is an important index for the interface stability. So, I am curious about how the impedance of the 3D knitted silver electrodes changes over time.
4. The electrode potential of 3D knitted silver electrodes should be measured in the revised manuscript. The offset potential and potential shifts should be compared with wet electrodes.
5. To remove the influence of electrode area, the area-normalized electrode-skin impedance should be reported. Please refer to Sensors & Actuators: B. Chemical 277 (2018) 250–260.
6. Nyquist plots for 3D knitted silver electrodes should be fitted by the proposed equivalent circuit model.
7. At least ten subjects should be enrolled for in-vivo measurements including electrode-skin impedance and in-vivo biopotential signal recording.
8. The signal quality should be quantificationally compared with the wet electrodes.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report (New Reviewer)
Comments and Suggestions for AuthorsI apperiate the novel of the aouthors. The manscuript is systemetic presents the matter. However, the following information should be inculded in the manscuript before the acceptence.
1. Title should be revised as "Development of 3D Biopotential electrodes and Intelligent garment system for sprt monitoring"
2. Need of the sudy should be strength with more information
3. For any monitoring device, accuracy is vital. In this case, i don't see any information related to that matter. What about accuracy of newly developed device? What method has been involved to estimate the accuracy of the device? RMSE? Error?
4. Similarly, for reliability, i don't. Same question as like accuracy. What method? How much reliable? etc.
5.No limiation has been inculded. Its should inculded
6. Future research directions also need to inculded.
Overall, the manscuript can be published after these minor revise.
6.
Comments on the Quality of English LanguageNone
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report (New Reviewer)
Comments and Suggestions for AuthorsThe manuscript is ready for publication in this journal after minor revision. Reference 20 "SmartMat 2023, e1173" should be corrected as "SmartMat, 2024, 5:e1173".
Author Response
Comments 1: The manuscript is ready for publication in this journal after minor revision. Reference 20 "SmartMat 2023, e1173" should be corrected as "SmartMat, 2024, 5:e1173".
Response 1: Thank you very much for your valuable suggestions. We have made the necessary correction to Reference 20, updating it to " SmartMat, 2024, 5:e1173" as recommended. Page 24, Line 732
This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsIn my opinion, manuscript #2911058: “Design, Fabrication, and Evaluation of 3D Biopotential Electrodes and Intelligent Garment System for Sport Monitoring”, needs major revision before being published. I strongly believe that this work is in the initial stage and can be significantly improved due to its high potential, however further research and state-of-the-art must be performed.
The manuscript describes a novel system of dry electrodes made with low-resistance silver fibres for integration into intelligent garment systems designed for sports monitoring. The authors were successful in recording ECG and EMG signals using their electrodes. However, validation tests with reference electrodes are necessary before the authors can claim a significant advancement for long-term sports monitoring.
Therefore, I recommend that the authors address the following questions and comments before publication:
1. Limited references and knowledge of the current state-of-the-art in dry electrodes: Scientific publications require a solid understanding and acknowledgement of previous work in the field. The manuscript should be thoroughly revised to incorporate more information and references to relevant studies.
1.1. Line 43: While the authors mention conductive elastomeric materials as an alternative to wet electrodes, several other promising approaches using conductive textiles have been explored in the literature. Please complete the manuscript providing specific examples with references.
1.2. Line 54-59: “The most used technologies are coating and embroidery. However, they demonstrate some significant limitations”. Please specify these limitations and provide supporting references.
1.3. Line 250: “Skin phantoms made from agar have been widely used in literature to evaluate the performance of biopotential electrode designs”. If so, please include relevant references.
2. The experimental design adopted for this work needs to be carefully revised, which once again requires an extra effort from the authors to revise the state-of-the-art and of course, the rules that need to be addressed during the biopotentials’ acquisition and recording.
2.1. According to the SENIAM rules, only two electrodes are needed to monitor the deltoid muscle. The authors used three electrodes. Even if one serves as a reference, it should be placed over a bone. The current configuration deviates from SENIAM guidelines and necessitates correction of electrode placement for both the deltoid and erector spinae muscles.
2.2. The authors referred to the use of laser-cut sponges matching the electrodes in size and thickness, assisted by velcro straps to maintain a close-skin electrode fit (Line 207). After a very interesting study regarding the influence of the pressure on the electrode's impedance, do the authors have any data on the pressure exerted by the electrode/garment on the skin?
2.3. The authors should revise the terminology employed in the manuscript. The most serious case is named the ADS1292R integrated circuit as sensors. The ADS1292R is a processing unit used for biopotentials recording that makes the interface with the electrodes/sensors of silver fibres. In this work, the 3D knitted silver electrodes detect the electrical signals generated by muscle activity, and the signals are then processed by the ADS1292R or similar ICs for amplification, filtering, and conversion into digital data. In the same vein, the manuscript refers to the use of actuators (line 191). Please clarify the function of these actuators in the context of this work.
2.4. The authors adapted a phantom from another study for impedance tests. Explain how this adaptation was performed. The phantom's white colour, contrasting with the black carbon phantom used by Goyal et al., is noteworthy. Please, provide a clear and detailed explanation for this difference.
3. Missing explanations in the Results and Discussion section: The results section lacks explanations for the observations presented. While the figures show trends in impedance magnitude and phase response, only impedance is discussed. In some cases, the figures show different trends for both parameters, yet the phase response is not analyzed (Figures 12-15). Here are additional suggestions for improvement:
3.1. Figure 3: SEM image. The authors need to revise the figures and provide the scale of the micrograph magnification.
3.2. Please clarify how the resistivity of the nylon filament with silver was measured. The SI unit for resistivity is Ωm, not Ω/m. Did the authors perhaps measure resistance instead?
3.3. Once again, I need to refer to the lack of discussion and explanation in the manuscript. “…the impedance incrementally rising as the pressure diminishes, a phenomenon that is especially marked at lower frequencies.” (Line 296) Why does that happen? Also, the electrodes with heights of 2.5 mm and 3 mm “display remarkably similar impedance behaviours” (line 280), Given this similarity, why was the 3 mm height chosen for further analysis?
4. Considering the Bio-Measurement Results several important information are missing.
4.1. How long take the cycling tests? As one volunteer participated in the study, was the study approved by an ethics committee?
4.2. The ECG results in Figure 17 lack discussion. What part of the exercise does this ECG correspond to? What is the reader supposed to interpret from this figure?
4.3. Please specify the scale of the EMG signals in Fig. 18-a.
Validation of biopotential electrodes requires a rigorous design, and to conclude about the performance of the electrodes it is necessary to conduct a parallel study with standard materials used in biopotential recordings (e.g. Ag/AgCl). While the authors express optimism, Figure 15 indicates that Ag/AgCl electrodes exhibit superior stability across frequencies compared to the 3D silver electrodes used in this study. Silver is highly susceptible to corrosion, especially in environments like sweat, which is prevalent during sports activities. More research is needed to address this critical concern before definitive conclusions can be drawn.
5. Several typos need to be revised in the manuscript. The most evident is the number of figures (Pag.11 all the figures mentioned are 14 and not 12) and in line 143 we have Figure 4 and not Fig.3. Also, the colour of the lines in Fig.18 (black and red) are wrongly mentioned in the manuscript as purple and orange (line 375).
Comments for author File: Comments.pdf
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThis paper introduces a novel approach utilizing 3D knitted electrodes for sport monitoring within continuous and integrated health monitoring systems employing digital devices. Overall, the article is well-structured, understandable, and effectively communicates relevant information. However, there is potential for enhancement in certain paragraphs and research content. Here are the specific comments on these aspects.
Comments:
1) The utilization of 3D knitted silver electrodes for sport monitoring is an innovative approach, offering promising results in reducing skin-to-electrode impedance. However, it would be great to conduct material-side research to prove its biocompatibility and long-term use age as a sport knit type physiological monitoring electrode system.
2) Regarding impedance measurement methodology, to enhance clarity, it would be great to provide a comparison with existing impedance measurement techniques, highlighting the advantages and limitations of the proposed method in relation to conventional approaches.
3) The adhesion between the skin and electrode is crucial as it directly impacts the quality of the signal. However, there is a lack of investigation regarding its attachment and the associated electrode performance.
4) Need to describe the skin issue with suggested optimized pressure on the electrode to have better signal quality since it is an on-skin clothing electrode system for sport. or conduct a further study regarding it.
5) The study related to skin sweat and electrode performance is to be confirmed.
6) I suggest including statistical analysis to quantify the accuracy and reliability of signal acquisition, providing robust evidence to support the system's performance.
Comments on the Quality of English LanguageOverall, the text is well-organized in terms of grammar and logic. However, there are some awkward expressions and grammatical errors that need to be corrected.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsSee the comments
Comments for author File: Comments.pdf
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for AuthorsThis study focused on design, fabrication, and evaluation of 3D biopotential electrodes and intelligent garment system. This 3D electrodes provide the low skin to electrode impedance and therefore a good quality bio-signals acquisition.
Some comments:
Should Figure 12 (a) and Figure 12 (b) be Figure 14 (a) and Figure 14 (b) on Line 305 and 306 ?
As Figure 15, at frequencies below 10Hz, the impedance of the 3D knitted silver electrodes is higher than that of Ag/AgCl electrodes. However, most physiological signals are at low frequency, such as ECG, EEG. PPG etc. The impedance at low frequency is more important.
This 3D knitted silver electrodes are more available to monitor EMG with high frequency.
In figure 17, could you compare ECG and its spectrum recorded by 3D knitted silver electrodes and Ag/AgCl electrodes at the same time?
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsDespite the authors' efforts to address minor revisions, such as completing the state-of-the-art and increasing the number of references, the main structural problems of the manuscript were not rectified. Additionally, the authors' responses indicate a high ambition for publication but also a disregard for basic rules. When fundamental questions related to pre-clinical tests were raised, the authors responded with statements such as: Our intelligent garment system is also designed with a holistic view, considering functional integration and wearer comfort alongside technical guidelines. While we appreciate the SENIAM standards, our design was optimized for a balance between functionality and user experience, which may not align perfectly with traditional EMG sensor designs” or "Our approach employed three electrodes, including a reference, due to the specific requirements of our wearable EMG sensor design". Rules exist to ensure that devices are tested consistently. If these rules were not followed, the proposed 3D Biopotential Electrodes cannot be properly evaluated. There are no guarantees about the signals being measured, and the authors are testing electrodes that cannot be claimed as biopotential electrodes, rendering the Intelligent Garment System for Sport Monitoring ineffective. I understand that such studies take time because they involve human beings. If the authors are unwilling to wait, they should consider monitoring other types of signals that do not involve humans to test the materials created.
The lack of scientific accuracy is evident, as the authors reference ECG recording without analysis and fail to use standard electrodes to compare the signals recorded. Additionally, they mention an anti-corrosion treatment for the Ag electrodes that was never discussed in the manuscript.
While I acknowledge the importance of scientific publication for authors, journals, and editors, scientific rigour cannot be compromised. The authors cannot create their own rules for publishing. For this manuscript to be considered for publication, it needs to undergo a complete revision. Alternatively, the authors could explore applications that do not involve human use, or they could submit the study for ethical approval and adhere to the standard rules for biopotential electrodes.
Reviewer 3 Report
Comments and Suggestions for AuthorsWell done
