Design and Implementation of a Low-Cost Chlorophyll Content Meter
<p>The low-cost chlorophyll meter presented in this work: external (<b>a</b>) and internal view (<b>b</b>).</p> "> Figure 2
<p>The experimental prototype sensor clip part of the device. Figures (<b>a</b>–<b>i</b>) show details from the concept design stage to the final implementation.</p> "> Figure 3
<p>The wiring diagram of the experimental chlorophyll meter device’s prototype.</p> "> Figure 4
<p>The designed model’s front (dimensions-WxLxH: 100 mm × 149.18 mm × 17 mm) and back cover (dimensions-WxLxH: 100 mm × 149.18 mm × 29.02 mm) of the “control box” are shown in (<b>a</b>,<b>b</b>), along with the 3D-printed parts (<b>c</b>). The designed (<b>d</b>) and constructed (<b>e</b>) simple, one-sided, auxiliary PCB is shown. In (<b>f</b>), the experimental meter is shown along with the two commercial chlorophyll meters, the SPAD-502 and atLeaf CHL Plus.</p> "> Figure 5
<p>Flowchart of the proposed chlorophyll meter device software’s operation pipeline.</p> "> Figure 6
<p>In (<b>a</b>), the 30 lemon leaves samples of experiment 1 are shown, selected to span a wide range of color shades (slightly yellow to dark green). In (<b>b</b>), a snapshot of some of the young Brussels sprouts growing in an experimental garden that were used for the measurements referred to in experiment 2. The chlorophyll meter measurements were all performed on-site, using all sensors and trying to avoid the major veins and to reach the leaf areas marked with the letters A to E in Figure (<b>c</b>) and A to C in Figure (<b>d</b>), in most cases. In each of these areas, 5 measurements were acquired, and the values were averaged prior to model fitting. The samples in (<b>a</b>) were collected to be photographed after being measured on-site.</p> "> Figure 7
<p>Color plastic filters in 5 different shades of green (no. 1, 2, 3, 4, 7, 8, 9, 10 in (<b>a</b>) and 13 in (<b>c</b>)) and 3 different shades of blue (no. 5, 6 in (<b>a</b>), 11, 12 in (<b>c</b>)) used for a low-cost evaluation of accuracy and repeatability of the 3 sensors. In (<b>b</b>,<b>d</b>) the transmission spectra of the samples are shown as acquired with a spectrophotometer. The numbers in the transmission spectra correspond to the numbers of the sample color filter used.</p> "> Figure 8
<p>In (<b>a</b>), a scatter plot showing the relation of data measurements with atLeaf CHL Plus and (<b>b</b>) with SPAD-502 as compared to the proposed sensor, on all 13 green and blue color filters.</p> "> Figure 9
<p>In (<b>a</b>), a scatter plot showing the correlation of data measurements with atLeaf CHL Plus and in (<b>c</b>), with SPAD-502 as compared to the proposed sensor, with only the 9 green color filters (numbered as 1, 2, 3, 4, 7, 8, 9, 10, and 13 in <a href="#sensors-23-02699-f007" class="html-fig">Figure 7</a>) used. (<b>b</b>,<b>d</b>) Plots of the residuals (marked with + in the Figure) for the simple linear regression model fit applied on data and plotted on (<b>a</b>,<b>b</b>). The norm of the residuals was calculated to be 0.2205 and 0.4520, for the atLeaf and SPAD-502, respectively.</p> "> Figure 10
<p>In Figures (<b>a</b>,<b>b</b>) the repetitive measurements on the 9 green-only color filters (numbered no. 1, 2, 3, 4, 7, 8, 9, 10, and 13 in <a href="#sensors-23-02699-f007" class="html-fig">Figure 7</a>) are shown. In (<b>a</b>), the measurements with atLeaf and SPAD are plotted while in (<b>b</b>) the same measurements with the proposed device are shown. The numbers on the plot correspond to the filters presented in <a href="#sec2dot3dot2-sensors-23-02699" class="html-sec">Section 2.3.2</a>, <a href="#sensors-23-02699-f007" class="html-fig">Figure 7</a>. The red and blue asterisks as well as the magenta star represent the mean of the 10 values plotted for each filter. Each value plotted is the mean of 5 measurements per point.</p> "> Figure 11
<p>Plot showing the standard deviation among each of the measurements performed, with the 3 sensors used, on the 9 green filters only (90 points in total, 10 random areas per filter, 5 measurements per point).</p> "> Figure 12
<p>(<b>a</b>) A scatter plot showing the relation of data measurements with atLeaf CHL Plus and the proposed sensor in this work, on 30 lemon tree leaves, while in (<b>c</b>) the relation with the SPAD-502 is shown for the same data measurements. The red (dotted) lines correspond to 95% confidence prediction intervals. In (<b>b</b>,<b>d</b>), plots of the residuals (marked with +) for the simple linear regression model fit in each case applied on data plotted on (<b>a</b>,<b>c</b>) are shown, respectively.</p> "> Figure 13
<p>(<b>a</b>) A scatter plot showing the relation of data measurements with atLeaf CHL Plus as compared to the proposed sensor in this work, on 32 Russel’s cabbage leaves, while in (<b>c</b>) the relation with the SPAD-502 is shown for the same data measurements. In (<b>b</b>,<b>d</b>), plots of the residuals (marked with +) for the simple linear regression model fit in each case, applied on data and plotted on (<b>a</b>,<b>c</b>) are shown, respectively.</p> ">
Abstract
:1. Introduction
2. Materials and Methods
2.1. Experimental Design
2.2. Device’s Operation and Software Pipeline
2.3. Data Acquisition
2.3.1. Data Acquisition on Leaves
2.3.2. Data Acquisition on Non-Leaves Samples
2.4. Device Accuracy Evaluation and Validation Metrics
3. Results and Discussion
3.1. Experimental Resuslts on Non-Leaves Samples—Accuracy Repeatability Evaluation
3.2. Experimental Results on Leaves Samples
3.3. Limitations and Comparison with Previous Studies
4. Conclusions and Future Outlook
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Acknowledgments
Conflicts of Interest
References
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Leaf Chlorophyll Meter | LED Light Sources Wavelengths Used (nm) |
---|---|
Konica Minolta SPAD-502+ | 650, 940 |
FT Green atLeaf CHL PLUS | 640, 940 |
Opti-Sciences CCM-200 | 653, 931 |
Force-A Dualex 4 Scientific | 710, 850 |
Hansatech Instruments CL-01 | 660, 940 |
PhotosynQ MultispeQ V1.0 | 655, 950 |
Apogee Instruments MC-100 | 653, 931 |
Yara International N-tester | 650, 960 |
Chlorophyll Meters | Lemon Tree (r) | Young Brussels Sprouts (r) | Blue and Green Filters (r) | Green Filters (r) |
---|---|---|---|---|
AtLeaf—proposed device | ||||
SPAD-502—proposed device |
Manufacturer’s Manual [23,25] | Estimated Values in This Study | |||
---|---|---|---|---|
Chlorophyll Meter | Accuracy | Repeatability | Accuracy | Repeatability |
atLeaf CHL Plus (atLeaf units) | [−0.6, +0.5] | 0.054 * | [−0.7, +0.6] | 0.0218 |
SPAD-502 (SPAD units) | .0 ** | 0.3 ** | [−0.6, +0.9] | 0.06 |
[−0.03, +0.02] | 0.0044 | |||
Proposed device (CHL-meter units) | n/a | n/a | 1.34 (atLeaf-units) | 0.2999 (atLeaf units) |
1.22 (SPAD units) | 0.2780 (SPAD units) |
Samples Measured | atLeaf CHL Plus Conversion Values * | SPAD-502 Conversion Values * |
---|---|---|
Lemon tree leaves | ||
Brussels sprouts leaves | ||
Non-leaves |
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Kamarianakis, Z.; Panagiotakis, S. Design and Implementation of a Low-Cost Chlorophyll Content Meter. Sensors 2023, 23, 2699. https://doi.org/10.3390/s23052699
Kamarianakis Z, Panagiotakis S. Design and Implementation of a Low-Cost Chlorophyll Content Meter. Sensors. 2023; 23(5):2699. https://doi.org/10.3390/s23052699
Chicago/Turabian StyleKamarianakis, Zacharias, and Spyros Panagiotakis. 2023. "Design and Implementation of a Low-Cost Chlorophyll Content Meter" Sensors 23, no. 5: 2699. https://doi.org/10.3390/s23052699