Electrode device for bioimpedance measurements of garden strawberry leaves

Abstract

FIELD: agriculture.SUBSTANCE: invention can be used in devices for diagnosing fungal diseases of garden strawberries, implementing the method of bioimpedance spectroscopy of leaves. The electrode device consists of two non-polarizing disk electrodes lubricated with conductive gel, mounted on clamp jaws. In working condition, the electrodes are positioned coaxially, with one electrode pressed against the upper surface of the strawberry leaf and the other against the lower surface. Thin-walled rings are placed on the electrodes so that cups are formed, the bottom of which are the electrodes, and the walls are the rings. The constancy of the gap between the electrodes is ensured by a limiter. The diameter of the electrodes allows them to be installed between the veins of the strawberry leaf.EFFECT: reduction in the influence of electrical interelectrode capacitance on the results of bioimpedance measurements of garden strawberry leaves.1 cl, 1 dwg

Description

[0001] The invention relates to the field of agriculture, namely to horticulture, and can be used in devices for diagnosing fungal diseases of garden strawberries, implementing the method of bioimpedance spectroscopy of leaves.

[0002] Garden strawberries account for a significant share of the global berry production. For example, in 2019, the harvest of garden strawberries accounted for 72% of the gross harvest of all berries in the world (9.7 million tons out of 13.4 million tons) [Ozhereliev VN, Ozherelieva MV, Grin AM, Somin VV Dynamics of garden strawberry production by country / / Bulletin of the Bryansk State Agricultural Academy. 2019. No. 4 (74). Pp. 60-66]. One of the limiting factors in strawberry production is the infection of cultivated varieties with fungal diseases, which leads to a decrease in the productivity of plantations, and sometimes to their death. The most common fungal diseases are white, brown and angular spot [Govorov DN, Govorov GF All about strawberries and strawberries. Moscow: ACT; Moscow: Kladez, 2023. 174 p.] As a result of the impact of pathogenic fungi on plants, the latter, in addition to mechanical [Domracheva L.I., Skugoreva S.G., Starikov P.A., Gornostaeva E.A., Ashikhmina T.Ya.Antagonist microbes against phytopathogenic bacteria and fungi (review) / / Theoretical and Applied Ecology. 2022. No. 2. pp. 6-14] and chemical changes [Dyakov Yu. T., Elansky S. N. General phytopathology: a textbook for the academic bachelor's degree. Moscow: Yurait Publishing House, 2016. 230 p], electrical properties also change. There is a change in the content of calcium, sodium, potassium and proton ions in the cytosol, depolarization of the plasma membrane and tonoplast, as well as a change in the parameters of the plasma membrane transport system [Tarchevsky I. A. Effect of elicitors on ion flows and electrical potentials of plants / / Bulletin of the Nizhny Novgorod University named after N. I. Lobachevsky. Biology Series. 2001. pp. 60-63]. From the point of view of express diagnostics, electrical changes are of greater interest, since they can be detected immediately after their occurrence, for example, by electrical impedance spectroscopy (EIS) methods [Wang YQ, Zhao PF, Fan LF, Zhou Q., Wang ZYDetermination of water content and characteristic analysis in substrate root zone by electrical impedance spectroscopy / / Computers and Electronics in Agriculture. 2019. Vol. 156. P. 243-253]. These methods require the installation of electrodes directly in plant tissue, usually in a leaf or stem, where measurements are taken between the electrodes. However, the invasive introduction of electrodes changes the properties of tissues in the damaged area and leads to necrosis of these tissues. For bioimpedance measurements of garden strawberry leaves, non-invasive methods of installing electrodes are more acceptable. In the work [Burynin D.A., Smirnov A.A., Proshkin Yu.A., Kachan S.A., Dolgalev A.P. Diagnostics in plant factories: a review of non-invasive methods for monitoring plant health for closed regulated agro-ecosystems / / Agroengineering. 2022. Vol. 24, No. 6. [P.70-75] a diagram of the measurement of the impedance of biological tissue of leaves using polymer electrodes is given.However, there is insufficient information on specific practical applications. Scientists from Singapore are working on creating an electrode device that can be attached to various plants with uneven or excessively hairy leaf surfaces [https: / / fb.ru / news / science / 2021 / 3 / 17 / 2952111. For this purpose, a special thermogel is being developed, which has a denser structure, which helps the electrode better cling to the microscopic leaf hairs. The thermogel is applied to the leaves in a liquid state and only then begins to thicken. This improves contact with the plant. Tests of the new thermogel are being conducted on sunflower stems covered with microscopic fluff. In the future, the scientists plan to make it available for all plants. An electrode device is known consisting of two "clothespin"-type clamps attached to the edge of a lettuce leaf at a distance of 3 cm from each other [Nouaze JC, Kim J.Hy., Jeon GR, Kim JHMonitoring of Indoor Farming of Lettuce Leaves for 16 Hours Using Electrical Impedance Spectroscopy (EIS) and Double-Shell Model (DSM). Sensors, 2022. 22. 9671. pp. 1–20. https: / / doi.org / 10.3390 / s22249671]. This method measures the impedance of the area of ​​plant tissue located between the clamps, which in this case serve as electrodes. A disadvantage of this device is that only the peripheral areas of the plant leaf are accessible for study. The closest to the claimed device is an electrode device (prototype) used in the study of the possibility of detecting spotting of garden strawberries by determining the parameters of the elements of equivalent electrical circuits based on the data of measurements of the bioimpedance of plant tissues of strawberry leaves using a precision impedance analyzer WK 6505 B (Wayne Kerr Electronics, UK) [Application of equivalent electrical circuits for the diagnosis of fungal diseases of garden strawberries / V.V. Mineev, O.V. Elkin, V.A.[Rikhter / / Information technologies, systems and devices in the agro-industrial complex. AGROINFO-2021: Proceedings of the 8th International scientific and practical conference, Krasnoobsk, October 21-22, 2021. Krasnoobsk: SFNTSA RAS, 2021. - Pp. 200-203]. The electrode device for bioimpedance measurements of garden strawberry leaves contains two non-polarizing disk electrodes with a diameter of 8 mm, lubricated with an electrically conductive gel, mounted on the jaws of a clothespin-type clamp in such a way that in the operating state they are coaxial, with one electrode pressed to the upper surface of the garden strawberry leaf, and the other to the lower. This device is characterized by the following disadvantages, leading to a change in the electrical capacitance between the electrodes and, as a consequence, to an additional error in determining the parameters of the elements of the equivalent electrical circuits.Firstly, the electrodes' dimensions prevent them from being positioned between the veins of the strawberry leaf, resulting in an inconsistent gap between the electrodes on both sides of the leaf. Secondly, inconsistency in the contact pressure also leads to variations in the gap between the electrodes. Thirdly, the flat surface of the electrodes prevents a consistent contact area with the strawberry leaf surface due to the gel applied to the electrode spreading when the electrode is pressed against the leaf.

[0003] The technical result of the invention is to reduce the influence of interelectrode electrical capacitance on the results of bioimpedance measurements of garden strawberry leaves.

[0004] The technical result is achieved in that the electrode device for bioimpedance measurements of garden strawberry leaves consists of two non-polarizing disk electrodes lubricated with an electrically conductive gel, mounted on the jaws of the clamp in such a way that in the working state they are coaxial, wherein one electrode is pressed to the upper surface of the garden strawberry leaf, and the other to the lower, thin-walled rings are put on the electrodes and secured so that cups are formed, the bottom of which are the electrodes, and the walls are the rings, and the clamp is equipped with a limiter, ensuring a constant gap between the electrodes when installing the device on a garden strawberry leaf, and the dimensions of the electrodes and rings are selected so that in the working state they allow their installation between the veins of the garden strawberry leaf.Thus, due to the fact that the dimensions of the electrodes are smaller than the distance between the veins of the strawberry leaf and the cup-shaped design of the electrodes does not allow the conductive gel to spread over the surface of the strawberry leaf, and the limiter does not allow the electrodes to come closer to each other than a specified distance, the electrical capacity of the electrodes, which depends on their area and the gap between them, remains practically unchanged when the electrodes are rearranged to different points on the strawberry leaf.

[0005] The figure shows a drawing (photograph) of the electrode device (for clarity - in the non-working open position with the help of a ring placed on the ends of the electrode device), explaining the essence of the invention.

[0006] Non-polarizing disk electrodes 1 are attached to connectors 2 using a detachable connection that ensures electrical contact between them. Connectors 2 are attached to jaws 3 of clamp 4 using glue. At clamp 4, jaws 3 are cut so that the surfaces of electrodes 1 are parallel in the working position. The necessary force for pressing the electrodes to the strawberry leaf is provided by a specially made spring 5. Thin-walled rings 6 made of fluoroplastic are placed on electrodes 1 in such a way as to form cups, the bottom of which are electrodes 1, and the walls are rings 6. The resulting bead limits the spreading of conductive electrode gel (not shown in the figure) when pressing electrodes 1 to the strawberry leaf. Thin fluoroplastic plates 7 are placed on thin-walled rings 6 for electrical insulation of the metal surface of connectors 2 in case of accidental contact with conductive electrode gel.A limiter 8, shaped like a needle with a pointed end, is attached to one of the plates 7. Limiter 8 ensures an initial gap between rings 6 approximately equal to the thickness of a strawberry leaf and a constant gap between electrodes 1 by pressing against the opposite plate 7 through a small puncture in the strawberry leaf. Alternatively, a non-invasive, but more complex, limiter design is possible. For example, it could be a "cylinder-piston" pair (not shown in the figure), secured to the corresponding ends of clamp 4, opposite jaws 3.

[0007] The electrode device operates in conjunction with electrical impedance meters, both industrial and specialized, for example, for diagnosing biological objects of plant origin, including fungal diseases of garden strawberries [Development of a portable impedance meter for diagnosing biological objects of plant origin / O.V. Elkin, V.B. Morozov, V.A. Richter, V.V. Mineev / / Information technologies, systems and devices in the agro-industrial complex. AGROINFO-2021: Proceedings of the 8th International Scientific and Practical Conference, Krasnoobsk, October 21-22, 2021. Krasnoobsk: Siberian Federal Scientific Center of the Russian Academy of Sciences, 2021. - P.178-180] and [Kuznetsov V.V., Novikov A.A. Technical implementation of bioimpedance polyfrequency spectrometry in diagnostic studies / / Omsk Scientific Bulletin. - No. 2 (120). - 2013. - P. 272-277].To conduct bioimpedance measurements on strawberry leaves, the garden operator, using the thumb and index finger of the left hand, presses the ends of clamp 4 opposite jaws 3, converting clamp 4 from its working (compressed) state to its open state. Using a brush, the operator then uses the right hand to fill the cups formed by rings 6 and the surface of electrodes 1 with electrode gel. Using a pad, the operator then smooths the applied gel mass flush with the edges of rings 6, removing any excess gel. Using the same hand, the operator inserts a strawberry leaf between the electrodes (without touching them), and using the left hand, by releasing the thumb and index finger, converts clamp 4 from its open state to its working (compressed) state at a selected point between the leaf veins. Connection to an impedance meter or specialized device is established via the electrical conductors of connectors 2.

[0008] The invention is implemented using the following main components. Electrodes 1 are taken from disposable H124SG electrodes from COVIDIEN (USA), their diameter is reduced by mechanical processing from 8 to 5 mm. Connectors 2 are manufactured by Neurosoft (Russia). Clothespins and garden plant tying devices, widely available on the market, were used as analogues in the manufacture of clamp 4. Electrode gel is "Akugel-Electro" manufactured by MediKraft LLC (Russia).

Claims

An electrode device for bioimpedance measurements of garden strawberry leaves, consisting of two non-polarizable disk electrodes lubricated with an electrically conductive gel, mounted on the jaws of a clamp in such a way that in the working state they are coaxial, wherein one electrode is pressed to the upper surface of the garden strawberry leaf, and the other - to the lower, characterized in that thin-walled rings are placed and secured on the electrodes so that cups are formed, the bottom of which are the electrodes, and the walls are the rings, and the clamp is equipped with a limiter, ensuring a constant gap between the electrodes when installing the device on a garden strawberry leaf, and the dimensions of the electrodes and rings are selected so that in the working state they allow their installation between the veins of the garden strawberry leaf.

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