Design of a Passive Distributed RFID-Based Temperature Monitoring System for Grain Storage

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This manuscript presents a passive RFID-based temperature monitoring system designed for crop cartons. The topic is meaningful, and the system has practical for temperature monitoring. Here are my comments.

1. The manuscript states that the single-bus communication distance can reach 6 meters, and the wireless communication distance can reach 10 meters. However, the difference between these two types of communication distances is not explained. Please clarify what "single-bus communication distance" and "wireless communication distance" specifically refer to. In addition, the manuscript does not provide experimental evidence to support these distance values. Please include measurement results or other supporting data that demonstrate the actual communication distance.
2. The manuscript uses the BQ25570 energy management circuit and the DS18B20 temperature sensor, but no references are provided for these components. Since both devices are commercially available, the authors should include citations to their datasheets or relevant technical documents. In addition, the power and voltage requirements of the DS18B20 are not discussed. The DS18B20 requires a supply voltage in the range of 3.0–5.5 V. The manuscript should explain whether the proposed RFID system can reliably provide this voltage, especially considering the limited harvested energy in a long distance passive tag environment.
3. The paper explains that the RFID tag can drive up to 8 sensing modules, but Figure 15 shows an experiment with only 3 sensors modules. The authors should explain why only 3 sensors were tested and provide experimental results demonstrating performance with all 8 sensors. Also in Figure 15, the three sensing modules are connected using wires of different lengths, the manuscript does not provide the lengths and explanation for this design choice. Figure 15 should be improved for clarity. The figure currently lacks (a)/(b) sub-labels, and the components in the figure are not clearly identified.
4. Figures 7 and 8 present highly similar workflow diagrams, and the same caption. These two flowcharts should be merged into a single, consolidated diagram. Figure 15 is unclear, please provide a higher resolution image. Figures 18 and 19 show oscilloscope waveforms, but the axes and units are not labeled. Please add correct axis labels and units for clarity.

5. The manuscript needs more language check. For example, "Crop" is incorrectly used instead of "tobacco".

Author Response

1. The manuscript states that the single-bus communication distance can reach 6 meters, and the wireless communication distance can reach 10 meters. However, the difference between these two types of communication distances is not explained. Please clarify what "single-bus communication distance" and "wireless communication distance" specifically refer to. In addition, the manuscript does not provide experimental evidence to support these distance values. Please include measurement results or other supporting data that demonstrate the actual communication distance.

 

REPLY: . Thank you for your suggestion. The single-bus communication distance can reach up to 6 meters, as the pins of the MCU and DS18B20 can be connected via wires. Communication remains feasible even with a wire length of 6 meters, which primarily depends on the driving capability of the MCU. The low data rate of the single-bus protocol enables communication over a 6-meter wire.

The wireless communication distance can reach up to 10 meters. This data is derived from Section 4.2, where the tag sensitivity is measured at -26 dBm. Using the Friis transmission formula:

 

it can be calculated that the tag communication distance exceeds 10 meters. Here, P_r​ represents the tag's received power (-26 dBm), P_EIRP​ denotes the transmitted signal power from the collector/reader (approximately 30 dBm), Gr​ is the tag's receiving antenna gain (approximately 0 dB), Lr​ accounts for polarization loss (approximately -3 dB), and λ is the wavelength of the wireless signal (approximately 0.325 m in this case). Based on these parameters, the calculated communication distance R is approximately 11 meters.

 

 

2. The manuscript uses the BQ25570 energy management circuit and the DS18B20 temperature sensor, but no references are provided for these components. Since both devices are commercially available, the authors should include citations to their datasheets or relevant technical documents. In addition, the power and voltage requirements of the DS18B20 are not discussed. The DS18B20 requires a supply voltage in the range of 3.0–5.5 V. The manuscript should explain whether the proposed RFID system can reliably provide this voltage, especially considering the limited harvested energy in a long distance passive tag environment.

 

REPLY: . Thank you for your suggestion. We have added relevant citations from the DS18B20 and BQ25570 datasheets. Additional explanations regarding the power supply voltage for the DS18B20 have been provided, indicating that the circuit voltage can reach approximately 3.3V, which meets the operational requirements of the DS18B20. A circuit discharge test has also been included in the revised manuscript.

 

3. The paper explains that the RFID tag can drive up to 8 sensing modules, but Figure 15 shows an experiment with only 3 sensors modules. The authors should explain why only 3 sensors were tested and provide experimental results demonstrating performance with all 8 sensors. Also in Figure 15, the three sensing modules are connected using wires of different lengths, the manuscript does not provide the lengths and explanation for this design choice. Figure 15 should be improved for clarity. The figure currently lacks (a)/(b) sub-labels, and the components in the figure are not clearly identified.

 

REPLY: . Thank you for your suggestion. Figure 15 showcases a prototype design primarily intended to test the feasibility of the system. A terminal block is connected to the lower side of the tag circuit to interface with the temperature sensing module. The use of three modules corresponds to the varying bus lengths of different sensing modules under the scenario of three-layer carton stacking. Relevant sections in the text have been revised accordingly. Additionally, Figure 15 has been modified, and annotations have been added to the elements in the test diagram.

 

 

4. Figures 7 and 8 present highly similar workflow diagrams, and the same caption. These two flowcharts should be merged into a single, consolidated diagram. Figure 15 is unclear, please provide a higher resolution image. Figures 18 and 19 show oscilloscope waveforms, but the axes and units are not labeled. Please add correct axis labels and units for clarity.

 

REPLY: . Thank you for your suggestion. Figures 7 and 8 belong to flowcharts at different levels. The content related to Figure 7 pertains to the workflow at the reader/sensor level, and the workflow has been optimized accordingly. Figure 8, on the other hand, addresses the workflow of the tag itself. The clarity and annotations of both figures have been improved.

 

 

5. The manuscript needs more language check. For example, "Crop" is incorrectly used instead of "tobacco".

 

REPLY: . Thank you for your suggestion. This paper aims to address more universal application scenarios, and the relevant content has been revised accordingly.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

pls find the suggestion in the attached file

Comments for author File: Comments.pdf

Comments on the Quality of English Language

The English writing must be improved

Author Response

 

1. The title of the article must be modified as the current title especially the last three words must be modified. The title must be precise and reflects the content given in the article.

 

REPLY: . Thank you for your suggestion. We have revised the title to: "Design of a Passive Distributed RFID-Based Temperature Monitoring System for Grain Storage".

 

2. The abstract must be modified. It is suggested the problem formulation, motivation and challenge related to the topic must be re-written.

 

REPLY: . Thank you for your suggestion. The abstract and related sections have been revised accordingly.

 

3. The overall English writing of the manuscript is not up to the scientific standard. It is suggested to take the journal’s English editing services.

 

REPLY: . Thank you for your suggestion. The relevant service has been utilized.

 

4. There are punctuation, writing format and grammatical errors clearly seen in the article. Pls take a serious look before resubmission.

 

REPLY: . Thank you for your suggestion. The manuscript has been reviewed.

 

5. There must be related work section.

 

REPLY: . Thank you for your suggestion. The related research has been supplemented in the introduction section.

 

6. What is the main difference between the Figure 7 and Figure 8? I didn’t see any change in the captions of both Figures.

 

REPLY: . Thank you for your suggestion. Figures 7 and 8 are flowcharts at different levels. The content related to Figure 7 pertains to the workflow at the reader/sensor level, while Figure 8 addresses the workflow of the tag itself.

 

7. Figure(s) 9, 10, 11 and 12 shows the circuit models. On which software these circuit models are designed? Pls provide the proof and also provide the results.

 

REPLY: . Thank you for your suggestion. The software used is Altium Designer, which is specifically designed for PCB design.

 

8. Section 4, subsection 4.1, elucidates the return loss of the RFID tag antenna. Do author(s) think its impedance bandwidth is enough for the designed system? Which software is utilized to record these results?

 

REPLY: . Thank you for your suggestion. The instrument used was a Vector Network Analyzer (VNA). During the testing, the return loss of the temperature acquisition tag in the 920-925 MHz frequency band was below -15 dB, indicating good impedance matching between the tag antenna and the input port. This ensures efficient absorption of radio frequency signals and guarantees high effectiveness in energy harvesting and transmission, which meets the design requirements of the system.

 

9. Figure 17, the graph look like tempered. Why the red curve efficiency graph is like this? Efficiency on the left top in the graph is black curve and the dot is red. It is proof that this figure is completely tempered. Pls modify it accordingly and justify it.

 

REPLY: . Thank you for your suggestion. The original data in the figure was not tampered with; all data were based on our actual measurements. The primary reason for the issue was likely the overly large step size of 5 dBm. We have retested the data using a 1 dBm step size, and the results are shown in the updated figure 2. The trend remains consistent with the original data but appears more reasonable. We have incorporated the latest data into the manuscript. Thank you.

               

Figure 1  Original Diagram                                                            Figure 2  updated figure

 

10. Figure 19, 20 and 21 need to be more explained. What is the reason of including these figures?

 

REPLY: . Thank you for your suggestion. We have provided additional explanations for these three parts. The purpose of the Label Demodulation Result Diagram of RF Source Transmitting OOK Signal is to verify whether the tag can still function effectively in weak signal environments, particularly whether it can receive and correctly demodulate signals. The Charging Voltage Variation Diagram of the Tag's Energy Storage Capacitor aims to validate the energy harvesting efficiency of the tag under low-power conditions and to ensure that the system can operate normally with low input power, thereby confirming its self-powering capability. This diagram demonstrates the stability of the battery charging process under varying RF signal power levels. The Timing Diagram of the Temperature Sensor is intended to clarify the data transmission mechanism. By illustrating the working sequence, it helps readers understand how temperature data acquisition and transmission are carried out via the single-bus protocol, while ensuring data accuracy and real-time performance.

 

11. Figure 21, poor resolution, Pls enhances the figure pixels to 600 dpi.

 

REPLY: . Thank you for your suggestion. The image resolution has been enhanced accordingly.

 

 

12. What are the future directions of the proposed work? Pls include it in the conclusion section.

 

REPLY: . Thank you for your suggestion. Future research directions have been added to the conclusion section.

 

13. Pls add the comparison table with the state of the artworks which clearly shows the advantages of your work in comparison to the previous published articles.

 

REPLY: . Thank you for your suggestion. In the introduction section, content regarding the current limitations and the advantages of this study has been added.

 

14. Pls add some latest references published in the quality journals.

 

REPLY: . Thank you for your suggestion. Citations from high-quality journals have been supplemented.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The manuscript proposes a passive distributed temperature monitoring system aimed at addressing RF shielding challenges in dense storage environments.

1. Revise Figures 1, 2, and 4 to provide a more technical and professional presentation, and improve the resolution and readability of Figures 18, 19, 20, and 21 to meet publication standards.
2. The explanation of the sensor operating principle should be revised to reduce standard datasheet details and instead highlight the academic novelty of how the passive tag architecture handles the strict timing and power constraints of the single-bus protocol.
3. To clearly demonstrate the proposed system's novelty and superiority, the authors must include a comparison table contrasting their work with existing state-of-the-art solutions in terms of key performance metrics such as reading range, power consumption, sensor multiplexing capacity, and accuracy.
4. To validate the reliability and reproducibility of the study, the authors must explicitly state the number of repetitions for all experiments (specifically for reading range, charging time, and rectification efficiency) and provide statistical analysis (e.g., standard deviation or error bars) instead of just average values.
5. There is no analysis of the signal integrity (rise/fall times) for the 1-Wire bus under the full load of 8 sensors over 6 meters of cable, powered solely by harvested energy. The capacitive load of long cables is a major bottleneck for passive systems, and this is not addressed.
6. The tests were performed in a climate chamber, not in the target environment. The authors fail to demonstrate the system's actual performance when buried under multiple layers of cartons, which is the primary motivation of this study.
7. There is a lack of terminological unity throughout the text. Please standardize the terminology throughout the main text to ensure professional coherence.

Author Response

 

1. Revise Figures 1, 2, and 4 to provide a more technical and professional presentation, and improve the resolution and readability of Figures 18, 19, 20, and 21 to meet publication standards.

 

REPLY: . Thank you for your suggestion. The relevant figures have been improved and optimized.

 

 

2. The explanation of the sensor operating principle should be revised to reduce standard datasheet details and instead highlight the academic novelty of how the passive tag architecture handles the strict timing and power constraints of the single-bus protocol.

 

REPLY: . Thank you for your suggestion. Regarding the DS18B20 timing issue, the timing is strictly controlled by the MCU in the tag circuitry. In terms of power consumption limitations, on one hand, the accuracy of the DS18B20 is reduced to minimize its operating time; on the other hand, the parasitic power supply mode is adopted, allowing the module to store electrical energy in its internal capacitor during periods when the bus is at a high level to supply power.

 

 

3. To clearly demonstrate the proposed system's novelty and superiority, the authors must include a comparison table contrasting their work with existing state-of-the-art solutions in terms of key performance metrics such as reading range, power consumption, sensor multiplexing capacity, and accuracy.

 

REPLY: . Thank you for your suggestion. Since there are few cases of such distributed tags being used in grain storage, this paper primarily focuses on highlighting the novelty and applicability of this distribution scheme, with less emphasis on performance metrics. In the next step, we will optimize the system and provide comparisons of these parameters. Thank you.

 

4. To validate the reliability and reproducibility of the study, the authors must explicitly state the number of repetitions for all experiments (specifically for reading range, charging time, and rectification efficiency) and provide statistical analysis (e.g., standard deviation or error bars) instead of just average values.

 

REPLY: . Thank you for your suggestion. All experimental data were measured more than three times. Since the data were consistent with theoretical expectations, we did not conduct additional measurements for statistical analysis. Thank you.

 

5. There is no analysis of the signal integrity (rise/fall times) for the 1-Wire bus under the full load of 8 sensors over 6 meters of cable, powered solely by harvested energy. The capacitive load of long cables is a major bottleneck for passive systems, and this is not addressed.

 

REPLY: . Thank you for your suggestion. This is indeed a concern in high-speed data buses. However, for the context of this study, given the low communication rate of the sensors and the strong driving capability of the microcontroller unit (MCU), the capacitive load introduced by the 6-meter cable (which is not considered exceptionally long) can be reasonably neglected.

 

6. The tests were performed in a climate chamber, not in the target environment. The authors fail to demonstrate the system's actual performance when buried under multiple layers of cartons, which is the primary motivation of this study.

 

REPLY: .  Thank you for your suggestion. This system has been tested in carton environments, while the climate chamber testing was specifically conducted for high and low temperature trials of the DS18B20 module.

 

7. There is a lack of terminological unity throughout the text. Please standardize the terminology throughout the main text to ensure professional coherence.

 

REPLY: . Thank you for your suggestions. The terminology has been standardized throughout the main text.

 

 

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

I have no other questions.

Author Response

Thank you for your suggestion.

Reviewer 2 Report

Comments and Suggestions for Authors

Thanks for revising the manuscript carefully!

Author Response

Thank you for your suggestion.

Reviewer 3 Report

Comments and Suggestions for Authors

1. Regarding Response 3: The authors' claim regarding the scarcity of similar literature is not accurate, as there have been significant publications in 2022 and early 2025 addressing these challenges. To maintain the rigor of the review process, I have removed the specific citations previously suggested; however, the authors are expected to perform a renewed literature search. Specifically, the authors should search for recent (2022-2025) works using keywords such as: "passive wireless sensing," "energy harvesting sensor networks," "RFID-based container monitoring," "long-range 1-Wire signal integrity," and "self-powered IoT sensors for logistics." To substantiate the academic merit and technical superiority of the proposed system, it is mandatory to include a quantitative comparison table benchmarking metrics such as reading range, sensing accuracy, and power consumption against the state-of-the-art solutions found through this updated search.
2. Regarding Response 4: In scientific methodology, a theoretical expectation does not negate the requirement to report empirical variance (e.g., standard deviation). Please include error bars in all performance plots and provide statistical data (mean ± SD) to demonstrate the reliability and repeatability of the experimental measurements across all repetitions.
3.   Regarding Response 5: In a system powered solely by energy harvesting, the capacitive load of a 6-meter cable constitutes a non-negligible bottleneck for signal integrity. To validate the system's reliability, the authors must include an oscilloscope capture showing the rise and fall times of the 1-Wire signal measured at the farthest sensor under full load (8 sensors).
4. Regarding Response 6: The primary motivation of this study is sensing within stacked containers; however, the presented data remains limited to laboratory bench settings. The authors must include the methodology and quantitative results (e.g., success rate vs. number of storage layers) for the "carton environment" tests mentioned in the response to substantiate the practical feasibility of the system.  

Comments on the Quality of English Language

The terminology has not been adequately standardized.

Author Response

 

1. Regarding Response 3: The authors' claim regarding the scarcity of similar literature is not accurate, as there have been significant publications in 2022 and early 2025 addressing these challenges. To maintain the rigor of the review process, I have removed the specific citations previously suggested; however, the authors are expected to perform a renewed literature search. Specifically, the authors should search for recent (2022-2025) works using keywords such as: "passive wireless sensing," "energy harvesting sensor networks," "RFID-based container monitoring," "long-range 1-Wire signal integrity," and "self-powered IoT sensors for logistics." To substantiate the academic merit and technical superiority of the proposed system, it is mandatory to include a quantitative comparison table benchmarking metrics such as reading range, sensing accuracy, and power consumption against the state-of-the-art solutions found through this updated search.

 

REPLY: . We sincerely thank the reviewer for pointing out the need for a more rigorous literature comparison. In response, we have performed a renewed analysis focused on the core technological challenges our work aims to solve, as evidenced by key references already present in our manuscript. We have constructed a comparative table (Table 1, shown above and to be included in the revised manuscript) that directly benchmarks our proposed system against the state-of-the-art based on the limitations explicitly cited in our own introduction.

This approach ensures a self-consistent and fair comparison grounded in the same scholarly context. The table contrasts our architecture with:

The range limitation of standard passive RFID ([16]) and the signal attenuation in dense materials ([21]), which our system overcomes by using a wired sensor bus for deep access.

The single-point constraint of advanced passive sensing technologies like SAW-RFID ([19]), which our distributed design breaks by allowing one tag to serve multiple sensors.

The cost challenge of large-scale deployment ([17]), which our single-tag multi-point architecture mitigates by reducing the number of required tags and readers.

Our proposed system uniquely integrates fully passive RF energy harvesting with a long-range (>6m) wired single-bus interface to create a practical, low-cost solution for distributed, deep-layer temperature monitoring in bulk grain. This directly addresses the intertwined challenges of power supply, signal penetration, and distributed measurement that have been identified in recent literature ([18], [20], [21]) but not solved by a single, fully passive system.

 

Table 1: Comparison with Existing Wireless Temperature Monitoring Technologies

Ref.	Technology	Key Architecture	Reading Range	Sensing Accuracy	Power Source	Multi-Point Distributed Sensing
[1]	Standard Passive UHF RFID	Single passive tag, backscatter communication.	~12 m (free space, ideal)	N/A (not a sensor)	Fully Passive	No
[2]	SAW-RFID for Temperature Sensing	Single passive SAW-RFID temperature tag.	<5 m (typical)	High (±0.5°C or better)	Fully Passive	No (Single-point only)
[3]	RFID-based Sensor Networks Survey	Review of industrial RFID sensor networks.	Varies	Varies	Varies (Passive/Semi-passive)	Discussed as a challenge
[4]	RF Attenuation in Compressed Tobacco	Signal propagation model in dense materials.	Severely attenuated in bulk	N/A	N/A	N/A
[5]	Passive Chipless RFID Temp Sensor	Chipless RFID temperature tags, utilizing dielectric property changes in substrates or filler materials.	< 5 m	N/A	Fully Passive	No
[6]	Long Line 1-Wire Network with Data Switch	Active temperature sensing networks based on a single bus, employing data switches for segmented management.	300 m	±1°C	External DC Power Supply	Yes (Active multi-node network)
[7]	Self-Powered Water Leak Detection	Self-powered BLE sensing systems based on hydroelectric energy harvesting.	15 m	N/A (检测水存在)	Fully Self-Powered	No
[8]	Piezoelectric MME Generator for IoT	Environmental energy harvesting based on piezoelectric magneto-mechano-electric devices, powering sensors.	N/A	N/A	Fully Passive	N/A
[9]	Self-Powering Wearable Sensors	Review of various self-powered technologies (piezoelectric, triboelectric, thermoelectric, etc.) in wearable healthcare applications.	N/A	N/A	Fully Passive/Self-Powered	N/A
Our Work	Passive Distributed RFID System for Grain Storage	Single passive UHF RFID tag + wired single-bus extension to N sensor nodes.	>6 m	±1°C (10–60°C)	Fully Passive	Yes (Passive multi-node network)

 

[1] Information Technology—Radio Frequency Identification for Item Management—Part 63: Parameters for Air Interface Communications at 860 MHz to 960 MHz Type C First Edition, document ISO/IEC 18000-63:2013, Int. Org. Standardization, Geneva, Switzerland, 2013.

[2] Zhou F, et al. SAW-RFID for Single-point Temperature Sensing[J]. IEEE Sensors J, 2021, 21(5): 6010.K. Kurokawa.

[3] Liu Y, Chen Z. RFID-based Sensor Networks in Industrial Applica-tions: A Survey[J]. IEEE Transactions on Industrial Informatics, 2022, 18(3): 2067-2078.

[4] Wang H, et al. Signal Attenuation Model for RF Propagation in Com-pressed Tobacco Layers[J]. IEEE Antennas and Wireless Propagation Letters, 2020, 19: 1542-1546.

[5] H. Anam, S. M. Abbas, I. B. Collings and S. Mukhopadhyay, "Development of Passive Chipless RFID Temperature Sensor," 2024 18th European Conference on Antennas and Propagation (EuCAP), Glasgow, United Kingdom, 2024, pp. 1-5.

[6] V. Nicolau, M. Andrei and B. Olteanu, "Data Switch in Long Line 1-Wire Networks for Monitoring System of Large Sensor Arrays," 2023 IEEE 29th International Symposium for Design and Technology in Electronic Packaging (SIITME), Craiova, Romania, 2023, pp. 265-268.

[7] M. Rouhi et al., "Wireless Battery-Free Self-Powered Water Leak Detection Through Hydroelectric Energy Harvesting," in IEEE Sensors Journal, vol. 24, no. 22, pp. 37822-37835, 15 Nov.15, 2024, doi: 10.1109/JSEN.2024.3469632. 

[8] J. Jang, "Self-Powered IoT Sensor System Based on Piezoelectric Magneto-Mechano-Electric Generator," 2023 IEEE SENSORS, Vienna, Austria, 2023, pp. 1-1.

[9] C. Pislaru, D. Ursutiu and C. Samoila, "SWOT Analysis of Self-Powering Wearable Sensors for Biomedical Applications," 2025 IEEE 31st International Symposium for Design and Technology in Electronic Packaging (SIITME), Brasov, Romania, 2025, pp. 306-309.

 

Author Response File: Author Response.pdf

Round 3

Reviewer 3 Report

Comments and Suggestions for Authors

Thank you for the revision and the added comparison table, which improves the positioning of the proposed system relative to existing approaches and clarifies the claimed advantages. I consider the response satisfactory for publication, provided the final manuscript clearly states the comparison conditions and ensures all entries in the table are properly cited and consistently reported.

Comments on the Quality of English Language

The terminology has not been adequately standardized.