Multi-Source Energy Harvesting Systems Integrated in Silicon: A Comprehensive Review

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The provided manuscript is devoted to attempt of analysis of publications with possible ways of combinations of multiple electrical sources for powering of autonomous low-power devices. The performed comparison is relevant and is interesting for readers. But the current version of the document looks like only the preliminary draft of the first analysis section. The considered multi-source circuits are trivial in itself, but they may represent models as the part of the method that would be proposed by authors in the next manuscript versions.

At the same time, the statistical comparison of existing parameters of solutions in publications does not have prognostic features and would be useless in nearest future. Moreover, it is not entirely clear what exactly is the main result of the work. Also, the formatting of the manuscript not fits the MDPI template, including format of all tables. The text requires partial reformulation for clarity.

It is necessary to consider following recommendations of improvement.

 

1. Please formulate clear goal and tasks of the work in academic form. If the second part of last paragraph in the Introduction section is the definition please reformulate it with obtaining of the universal multi-input system model of circuit as the result. It would summarize the already performed study for obtaining practically significant and reproducible result.

It can be formulated based on the results announced in the Abstract section that is good enough in current form. In the tasks list for the work in the last paragraph of Introduction section the generalization of model of multi-input energy harvesting system can be formulated.

 

2. It is proposed to consider the reorganization of all structure of the manuscript. Sections 2, 3, and 4 could be combined in a single section with subsections for each individual classification element. But after it is reasonable to add the section with the results or summarization of the analysis, and add the Discussion section before Conclusions.

It is reasonable after classification of possible ambient energy sources to highlight the existing multi-input circuits as the universal scalable models of acquisition because they are valid for different scales, not only for low power electronics, but for accumulator packs with currents of hundreds Amperes in electric vehicles or electric bikes. After that, it is reasonably to focus on the integrated implementations of such circuits with the analysis of known implementations and providing of the results in informative form. The Table 1 and Table 2 can be considered here as form of analysis results, but it would be interesting to analyze here the callings and drawbacks of integrated implementations, like the problem of powering the device if no one of the source is available or the power arrives as the rare pulses. These challenges would be the part of the proposed solutions or ideas within the entire work. After the end of the analysis of publication it is reasonable to add the section with the formulation of the challenges and probably the proposed solution for the problems of implementation of such integrated solutions for multi-sources acquisition.

Actually, even if the tracing of publication is the part of the current section with state of the art analysis, it is possible to move focus from the comparison results from the results provided at figures 6, 7, 8, 10, 11, 12, and 14 to the problem of energy harvesting models implementation (that were formulated in previous section). This result fits the announced in Abstract “to enhance efficiency, reliability, and scalability” and would be usefully as the basis for father researchers and publications. This is the key thing, because the model and problems are not depends on the time, but the tracing of current publications is relevant only today and won't be interesting in five or ten years. It is important as the result to provide the summarization that is already partially presented in your manuscript, but should be correctly highlighted.

 

3. Please consider renaming subsection titles to better represent the ideas and the study process in the manuscript. Subtitle '2.1. DC Output' must be reformulated, as well as '2.2. AC Output'. And please do the same for all subsections.

 

4. Please use MDPI template of electronics journal for proper presenting of tables 1, 2 and 3. While FoM is used in the analysis, please represent it as the formula with numeration.

 

5. Please also consider following recommendations and comments.

– If this manuscript is a Review, it is necessary to replace Article by Review in the line before title.

– Affiliation text should also provide initials of author (the shortings of the author's name) that are also presented in section Author Contributions. For authors 2 and 3 the initials are missed.

– Some sentences and paragraphs must be reformulated, because in the current form they are not informative for readers.

– Please ensure the explanation for all abbreviations before the first use (DC, AC). It should be done once.

– Part of the statements in Introduction section is more suitable for the Discussion section.

– Last paragraph in section 2 is separated from the rest text by new line.

– The Figure 2 appears before the reference to this figure (Fig. 2). The mentioning in the text should be before the Figure of Table. The same for Fig. 4., Table 1 and Table 2.

– The closing bracket at the end of keywords is redundant.

– Please rework the direct copying of text blocks from referenced publications (lines 124-126, 130-131, 133-136, 190-192, 210-211, 236-237, 256-257, 270-271, and second parts of pages 8, 9, 10, 15, 16 and pages 12, 13, 14 completely).

– Current version of the Conclusions section looks like a brief draft. Please provide here with the added Discussion section. The detailed information of the results should be provided here in direct from.

 

Comments on the Quality of English Language

Careful reading and reformulation of part of the long sentences will be enough for clear presentation of results in text.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Firstly, I would like to express my sincere gratitude for your submitted article, "Multi-Source Energy Harvesting Systems Integrated in Silicon: A Comprehensive Review." Given the current energy landscape and the explosive growth of IoT devices, your work could not be more timely and relevant. Your meticulous analysis of various energy harvesting technologies, along with your in-depth discussion of system architectures and performance metrics, provides readers with valuable insights.

The article exhibits a well-structured flow, progressing logically from the introduction to the conclusion. Your research on energy sources is extensive, covering photovoltaic, thermoelectric, mechanical energy harvesting, and RF energy harvesting. Moreover, your exploration of the advantages, challenges, and future directions for each technology is both comprehensive and thought-provoking. This thorough and detailed coverage enables readers to quickly grasp the current state of the field and its potential future developments.

However, I have a few suggestions that I believe could further enhance the quality of the paper. While your discussion of various energy harvesting technologies is highly comprehensive, supplementing it with experimental data or real-world application examples—such as organic solar cells and triboelectric nanogenerators—would be greatly beneficial. Such additional information would help readers develop a more concrete understanding of the potential and limitations of these technologies.

Additionally, although you have clearly defined and analyzed performance metrics and key parameters, I believe placing greater emphasis on the interrelationships between these metrics would be advantageous. For instance, a deeper discussion on the trade-offs between energy conversion efficiency and output power, along with strategies for optimizing these parameters in real-world scenarios, would be highly valuable. This would provide readers with a clearer understanding of the various considerations in designing multi-source energy harvesting systems.

Furthermore, while you effectively highlight the advantages of silicon integration, a more thorough discussion of the associated challenges would make your presentation more balanced. For example, although silicon integration indeed helps reduce parasitic losses and improve system reliability, it would be worthwhile to briefly mention the technical obstacles encountered during actual manufacturing, such as material compatibility and cost considerations. This would enhance the article’s practical relevance.

Lastly, the figures included in the article play a crucial role in conveying complex technical concepts. I recommend optimizing some of these visual aids to improve their intuitiveness and clarity. For instance, using color coding or more precise labeling could help distinguish different energy sources and system components, thereby enhancing reader comprehension.

In summary, your paper provides a comprehensive and insightful overview of silicon-integrated multi-source energy harvesting systems, making a significant contribution to advancing the field. I believe that by considering the above suggestions, the manuscript will be further refined and offer even greater value to readers.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

This is a well-structured and comprehensive review of multi-source energy harvesting systems integrated in silicon. The paper provides valuable insights into the state-of-the-art architectures, challenges, and trends in the field, with a focus on applications such as IoT, biomedical devices, and wireless sensor networks. Additionally, the inclusion of a figure of merit to evaluate performance is a strong point. However, there are areas that could be improved to enhance the manuscript's clarity, coherence, and overall quality. Below are the specific suggestions:

1. When mentioning energy harvest, people often associate it with wpt, such as Blind-zone-free metal object detection for wireless EV chargers employing DD coils by passive electromagnetic sensing, Noncooperative metal object detection using pole-to-pole EM distribution characteristics for wireless EV charger employing DD coils, Foreign object detection considering misalignment effect for wireless EV charging system, etc. Please clarify the boundaries between the two concepts in the Introduction, using the above literature.

2. In the introduction, the paper does a good job of motivating the study. However, it does not clearly articulate how this review differs from previous works in the field. I understand it is a review. However, novelty is still needed.

3. Line 86: "These attributes make these cells ideal for powering modern low-power IoT devices, including sensors, RFID tags, and Bluetooth beacons." The use of "these" is awkward and incorrect.

4. The tables, particularly Table 1 and Table 2, are highly dense and difficult to interpret at a glance. Please revise.

5. I understand that Figure 6 is about energy utilization, so the total does not equal 100%. However, it is strange to use a pie chart for this kind of data. Additionally, why are the values for each harvesting method so precise rather than presented as a range?

6. The section on simultaneous energy harvesting is promising but underdeveloped. It does not provide a detailed comparison of charge pump designs and inductor-based systems in terms of efficiency, scalability, and practical applications. Adding more critical analysis would help enhance the impact of this section.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Thank you for consideration the recommendations and comments. Your responce and improvements in the manuscript makes an impression. The significant work is done.
It can be useful for readers now.
During the final editing it is possible to pay attention to following:
- remove dot before citation [13] (was [10] in previous version) in the line 107 (remove '.' before [13].).

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Good efforts. No more comments.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf