Plant stalk carbon sink in-situ measurement device and method

Abstract

The invention relates to the technical field of plant physiology and ecology monitoring, in particular to a plant stalk carbon sink in-situ measuring device which comprises a split type shell used for being buckled on a plant stalk. A self-adaptive dynamic sealing system is arranged at a port, used for buckling plant stalks, of the split type shell; the self-adaptive dynamic sealing system comprises an inflatable elastic sealing piece and a pressure adjusting unit connected with the inflatable elastic sealing piece through a gas circuit. The invention also relates to a method for measuring the carbon sink of the plant stalk. The method comprises the following steps: closing the split shell on the periphery of the plant stalk to be measured through the two-stage locking mechanism; a dynamic measurement mode is entered; gas exchange data is recorded, and the split type shell is opened; the device can automatically fill gaps generated due to non-uniform stalk thickness and irregular surface texture, ensures airtightness, and ensures that the radial pressure intensity of the plant stalk is always limited in a safe range in which phloem tissues of the plant stalk are not damaged, so that the physiological authenticity of measured data is ensured.

Description

Technical Field

[0001] This application relates to the field of plant physiological and ecological monitoring technology, and requests protection for an in-situ measurement device for carbon sequestration in plant stems, as well as a method for measuring carbon sequestration in plant stems. Background Technology

[0002] In the context of global carbon cycle research and the "carbon peak, carbon neutrality" strategy, accurately quantifying the carbon sequestration capacity of forest ecosystems is crucial. Plants, as the main body of carbon fixation in ecosystems, have their different organs contributing significantly to carbon balance, making this a core area of ​​research. Traditional photosynthesis and respiration measurements primarily focus on leaves, as leaves are the main site of photosynthesis. However, plant stems (including tree branches and herbaceous plant stems) also undergo respiration, and under certain conditions, cortical photosynthesis, making them an indispensable part of the overall plant carbon balance. Ignoring the carbon flux of stems will lead to a systematic bias in the assessment of the carbon sequestration capacity of the entire ecosystem. To achieve in-situ measurement of carbon flux in plant stems, existing technologies typically employ a "stem chamber" (or "assimilation chamber") device. The basic principle is to attach a transparent or opaque cavity to the stem of the plant being measured, forming a sealed space isolated from the external environment. This space is connected to an external gas analyzer (such as a portable photosynthesis measurement system) via a gas pipeline, forming a closed-loop or open-loop measurement system. The respiration or photosynthetic rate of the stem is calculated by monitoring the rate of change of the concentration of gases such as CO2 in the cavity.

[0003] However, existing in-situ carbon sequestration measurement devices for plant stems generally suffer from problems such as poor sealing adaptability, easy damage to plants, susceptibility to air leakage due to environmental temperature, uneven internal flow field, and unsatisfactory optical environment, resulting in low measurement accuracy, poor data repeatability, and narrow applicability.

[0004] Specifically, this manifests as follows:

[0005] First, there are inherent defects in terms of sealing reliability and plant compatibility. Traditional stem chambers mostly use fixed-size rubber or silicone gaskets for sealing. The drawbacks of this "hard seal" method are obvious: 1) Poor compatibility: For plant stems of different diameters or with irregular surface textures (such as rough or segmented), a single size gasket is difficult to use universally, requiring frequent component replacements and limiting the applicability of the device. 2) Uncontrollable pressure: The locking force applied during installation depends entirely on the operator's experience. Excessive pressure can easily damage the epidermis and phloem tissues of the stem, affecting the normal physiological activities of the plant; insufficient pressure will not achieve an effective seal, leading to air leakage. To solve this problem, although some solutions (such as Chinese utility model patent CN206523490U) have proposed using inflatable airbag-type sealing rings, they can usually only be inflated once and lack a real-time monitoring and dynamic closed-loop control mechanism for sealing pressure. During long-term in-situ monitoring, the initial sealing pressure may change due to weak plant growth, changes in environmental temperature and humidity, or external disturbances, which may lead to seal failure or cause continuous stress on the plant.

[0006] Secondly, maintaining the airtightness of the measurement chamber itself presents challenges. For ease of installation, the housing of the measuring device is typically constructed from two or more parts joined together. During long-term field observations, diurnal variations or seasonal fluctuations in ambient temperature cause significant thermal expansion and contraction of the housing material. This deformation creates minute, dynamically changing gaps at the joints of the housing, compromising the airtightness of the entire measurement path and allowing external gases to infiltrate, causing unquantifiable interference with the measurement results. Current technologies generally lack effective solutions to this problem.

[0007] Third, there are shortcomings in the accuracy of simulating the internal environment of the measurement chamber. On the one hand, existing devices have relatively simple airflow organization designs within the chamber, typically only having simple inlets and outlets. This makes it difficult to create a uniformly mixed flow field within the chamber, easily generating gas concentration gradients or flow "dead zones" in local areas, resulting in unrepresentative samples collected by the gas analyzer and introducing measurement errors. On the other hand, to simulate the natural photosynthetic environment of plants, the chamber needs to be made of transparent materials. However, ordinary transparent materials lack spectral selectivity, potentially allowing excessive infrared radiation to pass through, leading to abnormally high internal temperatures (i.e., the "greenhouse effect"), or filtering out some photosynthetically active radiation. These issues can interfere with the true physiological state of the plant stems, reducing the reliability of the measurement data.

[0008] Therefore, developing an in-situ measurement device for carbon sequestration in plant stems that can achieve high precision, high adaptability, and high stability is of great practical significance for promoting plant physiological ecology research and serving the national "dual carbon" goals. Summary of the Invention

[0009] To address the technical problems mentioned in the background section, this application provides an in-situ measurement device for carbon sequestration in plant stems. This application also relates to a method for measuring carbon sequestration in plant stems.

[0010] This application provides an in-situ carbon sequestration measurement device system for plant stems, comprising: a split-type housing with an air inlet and an air outlet; the split-type housing is used to fasten onto a plant stem, and a cavity for measurement is formed between the inner wall of the split-type housing and the plant stem; the port of the split-type housing used to fasten onto the plant stem is provided with an adaptive dynamic sealing system; the adaptive dynamic sealing system includes: an inflatable elastic seal and a pressure regulating unit connected to the inflatable elastic seal via an air passage; the pressure regulating unit is used to maintain the internal pressure of the inflatable elastic seal constant within a set pressure threshold range.

[0011] Optionally, the inflatable elastic seal has a flexible contact layer facing the plant stem and a rigid contact layer that forms a mechanical seal connection with the port of the split housing for engaging the plant stem.

[0012] Optionally, the pressure regulating unit includes: a miniature air pump, a pressure sensor disposed in the air delivery pipeline, a pressure relief valve, and a controller; the controller is electrically connected to the miniature air pump, the pressure sensor, and the pressure relief valve respectively.

[0013] Optionally, the flexible contact layer has a different wall thickness than the rigid contact layer;

[0014] The flexible contact layer is a first silicone layer with a Shore hardness of 10A-20A. The surface of the first silicone layer is uniformly distributed with micron-level hydrophobic protrusions of irregular texture for adhering to the surface of plant stems.

[0015] The rigid contact layer is a second silicone layer with a Shore hardness of 40A-60A. The rigid contact layer and the first silicone layer are formed into an independent gas expansion cavity by a high-frequency hot pressing process.

[0016] The rigid contact layer and the split shell are bonded together at the port for fastening the plant stem to form an airtight sealed connection.

[0017] Optionally, the controller includes a pressure maintenance module; the maintenance module includes a hysteresis comparison circuit, the hysteresis comparison circuit being configured with a first voltage threshold corresponding to the lower limit of the pressure threshold and a second voltage threshold corresponding to the upper limit of the pressure threshold;

[0018] The pressure maintenance module is configured to prevent high-frequency oscillations in the pneumatic circuit at critical pressure points. It only outputs a control signal to change the on / off state of the micro air pump or pressure relief valve when the voltage signal output by the air pressure sensor jumps out of the hysteresis range defined by the first voltage threshold and the second voltage threshold.

[0019] Optionally, the joint surface of the split shell is sealed by a thermal response compensation sealing mechanism; the thermal response compensation sealing mechanism includes a shape memory alloy material with bidirectional memory effect, which is embedded in the sealing groove opened on the joint surface of the split shell, and is used to actively compensate for the gap caused by thermal expansion and contraction of the joint surface of the split shell when the ambient temperature changes.

[0020] Optionally, the thermal response compensation sealing mechanism includes an elastic rubber matrix and a nickel-titanium shape memory alloy wire array embedded in the matrix; the nickel-titanium shape memory alloy wire array is heat-treated and configured to undergo an austenitic phase transformation when the ambient temperature rises to the phase transformation point, generating a restoring force that contracts axially or bends radially, driving the elastic rubber matrix to deform to fill the gaps caused by the thermal expansion of the split shell.

[0021] Optionally, the split housing is made of a spectrally selective composite material; the composite material includes a transparent polymer substrate and a multilayer dielectric film deposited on the inner surface of the substrate by magnetron sputtering; the multilayer dielectric film is configured to have a transmittance of more than 90% for visible light with wavelengths of 400nm-700nm and a reflectance of more than 85% for infrared light with wavelengths of 700nm-2500nm.

[0022] Optionally, the cavity used for measurement is provided with a brushless vortex fan for generating a spiraling, downward, uniform airflow; the brushless vortex fan is fixedly connected to the inner wall of one of the split housings.

[0023] This application also provides a method for measuring carbon sequestration in plant stems, comprising the following steps:

[0024] S1: Close the split shell to the outer periphery of the stem of the plant to be tested through a two-stage locking mechanism;

[0025] S2: Perform airtightness self-test procedure: The controller controls the micro air pump to inflate the inflatable elastic seal to the upper limit of the damage threshold, then turns off the air pump and monitors the pressure drop within 30 seconds. If the pressure drop is less than the preset value, the seal is deemed qualified.

[0026] S3: Enter dynamic measurement mode: The controller dynamically maintains the pressure inside the inflatable elastic seal between 1.0 kPa and 2.0 kPa according to the logic of the hysteresis comparison circuit. At this time, the swirling flow field generating component is activated and the external gas analyzer is connected.

[0027] S4: Record gas exchange data, and after the measurement is completed, open the pressure relief valve to fully contract the inflatable elastic seal, and then open the split housing.

[0028] The advantages of this application compared to the prior art are:

[0029] This invention employs an adaptive dynamic sealing system that can automatically fill gaps caused by uneven stem thickness and irregular surface texture, ensuring airtightness. By dynamically maintaining the sealing pressure within a safe threshold range, it ensures that the radial pressure on the plant stem is always limited to a safe range that will not damage its phloem tissue, thereby guaranteeing the physiological authenticity of the measurement data.

[0030] This invention employs an inflatable elastic seal that combines a flexible contact layer and a rigid contact layer. This design satisfies both the rigid mechanical seal required for airtight connection between the seal and the split housing, and the flexible airtight connection between the split housing and the plant stem. This structural design provides excellent fit and conformability on the side facing the plant stem, while providing a secure mechanical fixation on the side facing the housing, preventing the seal from twisting or detaching from the mounting groove during inflation. This design also avoids the contradiction between the rigidity and flexibility requirements of a single material, resulting in a seal that not only possesses excellent sealing performance but also has a longer service life and higher structural stability.

[0031] This invention constructs a complete negative feedback control system through the coordinated operation of a pressure sensor, controller, micro air pump, and pressure relief valve, which upgrades the sealing pressure from "open-loop" manual adjustment to "closed-loop" intelligent automatic maintenance, significantly improving the automation level and reliability of the device.

[0032] This invention ensures ultra-flexible contact with the stem surface by using a low-hardness silicone layer of 10A-20A, minimizing stress concentration; while a high-hardness silicone layer of 40A-60A guarantees installation stability. This gradient design is key to performance optimization. Furthermore, the micron-level hydrophobic protrusions not only increase hydrophobicity, preventing moisture retention and stem disease, but also reduce the contact area, lowering the risk of adhesion and damage to the stem epidermis during disassembly. High-frequency hot-pressing ensures a robust, airtight gas expansion cavity between the two layers, preventing interlayer delamination or leakage and guaranteeing the reliability of the seal as an actuator.

[0033] This invention employs a key control strategy—a hysteresis comparator circuit—to ensure stable system operation. By setting a "hysteresis range" comprised of upper and lower pressure thresholds, the controller only activates when the pressure significantly exceeds this range. This effectively prevents frequent start-stop cycles of the miniature air pump and pressure relief valve due to minute fluctuations at critical pressure points, avoiding mechanical wear and energy waste. Furthermore, this design effectively prevents vibration, resulting in smooth and deterministic control actions. This significantly enhances the stability and reliability of the entire system under long-term unattended operation, providing a crucial technical guarantee for achieving the goal of "long-term in-situ measurement."

[0034] The structural solution of this invention employs a mechanism of "driving elastic rubber matrix deformation," combining the macroscopic mechanical properties of SMA with the elasticity of rubber. By further providing active and intelligent gap compensation, it clearly utilizes the phase transformation characteristics (austenitic phase transformation) of shape memory alloy (SMA) to generate restoring force, thereby driving the deformation of the sealing strip. This is an active, temperature-triggered adaptive behavior, and compared to passive elastomers, its compensation effect is more timely and effective.

[0035] This invention employs a shell made of spectrally selective composite material, whose performance, combined with the thermal response compensation mechanism, creates a synergistic effect, suppressing thermal interference at its source: By utilizing highly reflective infrared light (700nm-2500nm), it significantly reduces the "greenhouse effect" temperature rise in the measurement cavity caused by sunlight exposure, providing a more stable and natural microenvironment for measurement; by utilizing highly transmittance visible light (400nm-700nm), it ensures normal photosynthesis in the measured stem segment, avoiding measurement errors introduced by changes in light conditions and fully protecting the plant's normal physiological activities. Furthermore, the above-mentioned methods, in conjunction with the thermal response compensation sealing mechanism, constitute a systematic, multi-layered solution for compensating for thermal deformation and addressing environmental temperature changes.

[0036] This invention optimizes the gas mass transfer efficiency within the cavity by employing a brushless vortex fan as the swirling flow generation component. By generating swirling flow, the static gas boundary layer tightly adhering to the stem surface is effectively disrupted, allowing gases produced by stem respiration or photosynthesis to quickly mix with the main airflow, thus improving the measurement response speed and accuracy. More uniform gas mixing means that the gas analyzer can detect minute changes in gas concentration more quickly and accurately, thereby improving the timeliness and accuracy of the entire system's measurement data. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the in-situ carbon sequestration measurement device for plant stems in Embodiment 1 of this application.

[0038] Figure 2This is a schematic diagram of the adaptive dynamic sealing system in Embodiment 1 of this application.

[0039] Figure 3 This is a schematic diagram of the structure of the inflatable elastic seal in Embodiment 2 of this application.

[0040] Figure 4 This is a partial cross-sectional view of the thermal response compensation sealing mechanism in Embodiment 3 of this application. Detailed Implementation

[0041] The following are examples of specific implementation processes provided to illustrate the technical solutions to be protected in this application. However, this application may also be implemented in other ways different from those described herein. Those skilled in the art can implement this application by different technical means under the guidance of the concept of this application. Therefore, this application is not limited to the specific embodiments below.

[0042] Example 1:

[0043] like Figure 1 The accompanying drawing illustrates one possible structural form of the in-situ carbon sequestration measurement device for plant stems in this embodiment. The structure includes a split-type housing. This split-type housing is detachable and combinable, designed to easily wrap around the stems of living plants without damaging them. In one possible implementation, as shown, the split-type housing can be composed of an upper hemispherical housing 100 and a lower hemispherical housing 200 interlocked. Of course, the specific form of the split-type housing is not limited to this; for example, it can be two semi-cylinders, or composed of three or more interlocking lobes, as long as they can be combined to form a closed structure surrounding the plant stem. For easy opening and closing, the different parts of the split-type housing can be connected by existing pivoting mechanisms such as hinge components 300, and an existing locking component 400 (a transparent locking component as shown) is provided on the other side for closing and locking. The materials used for the split-type shells are usually those with good light transmittance, such as optical-grade polymethyl methacrylate (PMMA), to ensure that external natural or artificial light sources can effectively illuminate the surface of the wrapped plant stems when photosynthesis measurements are being performed.

[0044] The split-type housing is equipped with an air inlet 500 and an air outlet 600. These two interfaces serve as channels for gas communication between the device and external gas analysis equipment (such as a photosynthesis unit). The air inlet 500 introduces gas from the gas analysis equipment into the housing, while the air outlet 600 discharges gas from the housing after gas exchange with the plant stems back to the analysis equipment, thus forming a closed-loop or open-loop gas circulation measurement system. These interfaces can utilize standard connectors commonly used in the art, such as Luer joints, to ensure quick connection and airtightness.

[0045] When the split-type shell is attached to the plant stem, a cavity for measurement is naturally formed between its inner wall and the outer surface of the plant stem. This cavity is a relatively sealed space, and changes in its internal gas composition, such as carbon dioxide concentration and water vapor content, will directly reflect the physiological activities of the measured stem segment, including but not limited to photosynthesis or respiration.

[0046] like Figure 2 As shown, as one of the core improvements of this invention, the port of the split-type shell used to fasten the plant stem is equipped with an adaptive dynamic sealing system. Here, the port refers to the opening reserved on the split-type shell for the plant stem to pass through. Since the surface of plant stems is often irregular and varies in diameter, traditional fixed-size sealing rings are difficult to achieve universal and reliable sealing. The adaptive dynamic sealing system in this embodiment aims to solve this technical problem. The system includes an inflatable elastic seal 700 and a pressure regulating unit 800 connected to the inflatable elastic seal via an air passage. The inflatable elastic seal 700 is a flexible component whose shape and sealing pressure can be changed by inflating or deflating. Structurally, it can be a hollow, annular airbag made of elastic material (such as silicone rubber, latex, etc.) containing a C-shaped opening, such as... Figure 2 An inflatable silicone sealing ring is set around the stem passage hole. When not inflated, its inner diameter and C-shaped opening are large, making it easy for the plant stem to pass through; when inflated, it expands inward and gently conforms to the surface of the plant stem to fill all irregular gaps, thereby forming a reliable airtight seal between the two ends of the C-shaped opening and the inner wall of the inflatable silicone sealing ring and the plant stem.

[0047] In the above structural scheme, to achieve the adaptive and dynamic adjustment of the adaptive dynamic sealing system, the pressure regulating unit is functionally configured to maintain the internal pressure of the inflatable elastic seal constant within a set pressure threshold range. The pressure regulating unit can be broadly defined as an integrated system including a pressure source, a pressure release mechanism, a pressure sensing component, and control logic.

[0048] Its working principle can be explained as follows: First, the operator or system presets a suitable pressure threshold range, such as 1.0 kPa to 2.0 kPa. This range is set based on the principle that the lower limit must ensure sufficient sealing pressure to prevent leakage, while the upper limit must ensure that the pressure does not cause physical damage to tissues such as the phloem of the plant stem. After measurement begins, the controller within the pressure regulating unit starts working. It continuously acquires the real-time pressure value inside the inflatable elastic seal from the pressure sensing component.

[0049] When the controller detects a real-time pressure value below the set lower pressure threshold (e.g., below 1.0 kPa), it may indicate insufficient sealing pressure due to temperature changes or minor material deformation. The controller will then activate a pressure source (e.g., a miniature air pump) to replenish the inflatable elastic seal with gas, restoring its pressure. Conversely, when the controller detects a real-time pressure value above the set upper pressure threshold (e.g., above 2.0 kPa), this could pose a risk of damage to the plant. The controller will then activate a pressure release mechanism (e.g., a miniature pressure relief valve) to release some gas, allowing the pressure to drop back to a safe range.

[0050] Through this closed-loop negative feedback control method, the pressure regulating unit ensures that the sealing pressure applied to the plant stem by the inflatable elastic seal is always maintained within an optimal, dynamically balanced range. It not only adapts to plant stems of different diameters and surface roughnesses, achieving effective sealing upon one-time installation, but also automatically compensates for pressure fluctuations caused by factors such as changes in ambient temperature, weak plant growth, or creep of the device materials during long-term continuous monitoring, thus ensuring that the airtightness of the measuring chamber remains stable and reliable.

[0051] By adopting the above technical solution, the in-situ carbon sequestration measurement device for plant stems of the present invention utilizes an adaptive dynamic sealing system including a pressure regulating unit to achieve flexible, non-destructive, and dynamically stable sealing of plant stems. This fundamentally solves the problems of air leakage or plant damage caused by poor adaptability and uncontrollable pressure in traditional sealing methods, greatly improving the accuracy and reliability of in-situ measurement data, and providing a solid technical guarantee for accurately quantifying the carbon sequestration capacity of plant stems.

[0052] It should be noted that the in-situ carbon sequestration measurement device for plant stems provided in this embodiment has integrated control logic and data processing functions that can be executed by one or more processors. In a specific application scenario, the technical solution of this device can be implemented by a controller integrated on the device, or by an external control terminal connected to the device via wired or wireless connection. This embodiment uses the controller described later as the execution subject of the method, but this should not be regarded as the only limitation on the execution subject.

[0053] Example 2:

[0054] like Figure 3As shown, in this embodiment, the structure of the inflatable elastic seal is further optimized. In a preferred embodiment, the inflatable elastic seal 700 has a flexible contact layer 710 facing the plant stem and a rigid contact layer 720 that forms a mechanical seal with the port of the split housing for engaging the plant stem. This dual-layer composite structure design aims to balance flexible protection for the plant with a rigid and stable connection with the device body, achieving functional decoupling and optimization.

[0055] Specifically, the flexible contact layer is the part of the inflatable elastic seal that directly contacts the surface of the plant stem. To best adapt to the irregular surface texture of the plant stem and avoid any damage, this layer is made of a very soft and highly elastic material. When inflated, it can adhere to every tiny bump and groove of the stem with extremely low stress, enveloping the stem surface like a liquid, thus forming a seamless airtight barrier without damaging the plant tissue. The rigid contact layer is the part that securely connects the inflatable elastic seal to the split housing. Its function is to provide a stable base and structural support for the entire elastic seal. Therefore, the material of this layer has relatively high hardness, is relatively stable in shape, and is not easily deformed. Through this rigid contact layer, the inflatable elastic seal can be firmly and airtightly installed on the port of the split housing, for example, by adhesive, snap-fit, or screw connection. This firm connection ensures that the elastic seal will not detach from the housing or shift during inflation and pressurization, long-term use, or external disturbances, guaranteeing the structural integrity and long-term stability of the entire sealing system.

[0056] By designing the inflatable elastic seal as a composite structure with a flexible contact layer and a rigid contact layer, this invention achieves a clever division of functions: the flexible contact layer is dedicated to seamlessly and perfectly conforming to the plant, achieving a seal for dynamic organisms; the rigid contact layer is dedicated to securely and reliably connecting the device, achieving a seal for static mechanical bodies. This design not only improves the reliability of the seal and the protection of the plant, but also simplifies the installation and maintenance process, as the rigid contact layer provides a stable and reliable mounting surface, making it easier to replace or repair the elastic seal.

[0057] Preferably, in one of the preferred technical solutions of this embodiment, the pressure regulating unit includes: a miniature air pump, a pressure sensor disposed in the air guide pipe, a pressure relief valve, and a controller; the controller is electrically connected to the miniature air pump, the pressure sensor, and the pressure relief valve respectively.

[0058] Example 3:

[0059] In one specific implementation of this embodiment, the wall thicknesses of the flexible contact layer and the rigid contact layer can be designed to be different. Typically, the flexible contact layer can be designed to be thinner so that it can deform more easily during inflation, thereby achieving full adhesion to the plant stem surface with less pressure. The rigid contact layer, on the other hand, can be designed to be thicker to provide sufficient structural strength and stability.

[0060] Regarding material selection, the flexible contact layer can be specifically defined as a component composed of a first silicone layer, with a Shore hardness preferably between 10A and 20A. Silicone materials within this hardness range are extremely soft, with a gel-like feel, ensuring that no indentation or mechanical damage occurs when in contact with living plant tissue. To further enhance its adaptability to irregular surfaces and sealing performance, the surface of the first silicone layer can also undergo special treatment, such as uniformly distributing micron-level hydrophobic protrusions to conform to the irregular texture of the plant stem surface. These micron-level protrusions, on the one hand, act like countless tiny tentacles, penetrating deep into the tiny crevices of the plant stem bark to form a more reliable labyrinthine seal; on the other hand, their hydrophobic properties effectively prevent the accumulation of plant sap or external rainwater and dew at the sealing interface, avoiding potential seal failure or maceration damage to the plant epidermis due to the presence of liquid.

[0061] Correspondingly, the rigid contact layer can be specifically defined as a component composed of a second silicone layer, preferably with a Shore hardness of 40A to 60A. Silicone materials in this hardness range have good rigidity and shape retention, while still retaining a certain degree of elasticity, making them very suitable as a base for rigid connection with the device housing.

[0062] These two silicone layers with different hardnesses—the rigid contact layer and the first silicone layer—can be integrally molded using processes such as high-frequency hot pressing, thereby forming an independent, closed gas expansion cavity between them. The high-frequency hot pressing process ensures that the two layers fuse at the molecular level at the interface, forming a uniform and strong bond, thus guaranteeing the long-term airtightness of the gas expansion cavity.

[0063] Finally, the outer surface of the rigid contact layer can be fixed to the inner wall of the port of the split housing used to fasten the plant stem by means of adhesive bonding, for example, to form a permanent, airtight seal. Because the rigid contact layer itself is morphologically stable, the bonding interface can be made very regular and smooth, thereby ensuring the strength and airtightness of the connection between the elastic seal and the device housing.

[0064] By specifying the wall thickness, material hardness, surface microstructure, and manufacturing process of the flexible and rigid contact layers as described above, the inflatable elastic seal of this invention not only achieves non-destructive flexible sealing but also further enhances its adaptability to complex surfaces, its anti-contamination ability, and its structural stability in connection with the device body, making the performance of the entire adaptive dynamic sealing system more outstanding and reliable.

[0065] Preferably, in one of the preferred technical solutions of this embodiment, the controller includes a pressure maintenance module; the maintenance module includes a hysteresis comparison circuit, the hysteresis comparison circuit is configured with a first voltage threshold corresponding to the lower limit of the pressure threshold and a second voltage threshold corresponding to the upper limit of the pressure threshold; the pressure maintenance module is configured to prevent the pneumatic circuit from oscillating at the critical pressure point, and only outputs a control signal to change the switching state of the micro air pump or pressure relief valve when the voltage signal output by the air pressure sensor jumps out of the hysteresis range defined by the first voltage threshold and the second voltage threshold.

[0066] Preferably, in one of the preferred technical solutions of this embodiment, the joint surface of the split shell is sealed by a thermal response compensation sealing mechanism; the thermal response compensation sealing mechanism includes a shape memory alloy material with bidirectional memory effect, which is embedded in the sealing groove opened on the joint surface of the split shell, and is used to actively compensate for the gap caused by thermal expansion and contraction of the joint surface of the split shell when the ambient temperature changes.

[0067] Preferably, such as Figure 4 As shown, in one preferred embodiment, the thermal response compensation sealing mechanism 900 includes an elastic rubber matrix and a nickel-titanium shape memory alloy wire array 910 embedded in the matrix. The nickel-titanium shape memory alloy wire array is heat-treated and configured to undergo an austenitic phase transformation when the ambient temperature rises to the phase transformation point, generating a restoring force that contracts axially or bends radially, driving the elastic rubber matrix to deform and fill the gaps caused by the thermal expansion of the split shell.

[0068] Preferably, in one of the preferred technical solutions of this embodiment, the split shell is made of a spectrally selective composite material; the composite material includes a transparent polymer substrate and a multilayer dielectric film deposited on the inner surface of the substrate by magnetron sputtering; the multilayer dielectric film is configured to have a transmittance of more than 90% for visible light with wavelengths of 400nm-700nm and a reflectance of more than 85% for infrared light with wavelengths of 700nm-2500nm.

[0069] Preferably, such as Figure 1 and Figure 2As shown, in one preferred embodiment, a brushless vortex fan WS for generating a spirally descending uniform airflow is provided in the measurement cavity; the brushless vortex fan WS is fixedly connected to the inner wall of one of the split housings. This invention optimizes the gas mass transfer efficiency within the cavity by employing a brushless vortex fan as the vortex field generating component: by generating vortex flow, the static gas boundary layer tightly adhering to the stem surface is effectively disrupted, allowing gases generated by stem respiration or photosynthesis to quickly mix with the main airflow, thus improving the measurement response speed and accuracy; more uniform gas mixing means that the gas analyzer can detect minute changes in gas concentration faster and more accurately, thereby improving the timeliness and accuracy of the entire system's measurement data.

[0070] It should be noted that the power supply method of the above-mentioned brushless vortex fan WS is based on existing technology. It can be preferably powered by connecting an external power source to an airtight through-wall electrode, or by using a built-in lithium battery and a charging induction coil for wireless charging with an external charging device.

[0071] Example 4:

[0072] This invention also provides a method for measuring carbon sequestration in plant stems. This method, through a series of standardized operating steps, ensures the convenience, accuracy, and repeatability of the measurement. The method mainly consists of the following steps:

[0073] Step S1: Close the split shell to the outer periphery of the stem of the plant to be tested through a two-stage locking mechanism.

[0074] In practice, the operator first selects the stem portion of the plant to be measured and places two or more parts of the split-type housing on both sides of the stem. Then, the split-type housing is closed and secured using a locking mechanism. This two-stage locking mechanism can be understood as a closing device with two locking stages or functions. For example, the first stage of locking can be a preliminary latch or positioning, allowing the split-type housing to be correctly aligned and closed around the stem, but not yet fully compressed; the second stage of locking, after confirming the correct position, uses a final pressing, rotating, or lever action to firmly clamp the housing, ensuring it will not shift during measurement. This staged locking method helps the operator accurately install the device, avoiding positional deviations or accidental damage to the plant caused by excessively rapid locking at once. In one possible implementation, this mechanism can be specifically represented as the locking assembly 4 shown in the attached drawings of the technical disclosure document.

[0075] It should be noted that the above two-stage locking mechanism is an existing mechanical locking connection method. It is preferable to use a combination of magnetic initial positioning and eccentric wheel mechanical locking structure to ensure convenient operation while achieving a firm closure effect.

[0076] Step S2: Perform the airtightness self-test procedure.

[0077] After the device is physically installed, to ensure the validity of subsequent measurements, the controller will automatically or under user instruction execute an airtightness self-check procedure. This step aims to quickly verify the integrity of the sealing system before commencing long-term measurements. Specifically, the controller first controls the miniature air pump to inflate the inflatable elastic seal until its internal pressure reaches a preset damage threshold. This damage threshold is higher than the normal operating pressure but far below the critical pressure that could damage the plant or the seal material; for example, it can be set to 3.0 kPa. Once this pressure is reached, the controller immediately shuts off the miniature air pump and the pressure relief valve, placing the air system in a closed, pressure-maintaining state. Next, the controller monitors and records the pressure drop inside the inflatable elastic seal over a set period (e.g., 30 seconds) using a pressure sensor. Finally, the controller compares the actual pressure drop during this period with a preset allowable pressure drop threshold. If the actual pressure drop is less than the preset value, the entire measuring chamber is considered sealed and the next step can proceed; if the pressure drop is greater than the preset value, it indicates a leak, and the system can issue an alarm to prompt the operator to check and reinstall the seal.

[0078] Step S3: Enter dynamic measurement mode.

[0079] Once the airtightness self-test is passed, the system officially enters the dynamic measurement mode. In this mode, the core task of the controller is to dynamically and precisely maintain the pressure within the inflatable elastic seal within a preset working pressure range that is safe for the plant and ensures effective sealing, such as 1.0 kPa to 2.0 kPa, using the logic of the hysteresis comparison circuit as described in claim 5. By employing hysteresis comparison logic, high-frequency switching actions of the air pump and pressure relief valve due to small fluctuations near the pressure critical point can be effectively avoided, thereby improving the system's energy efficiency and service life. While maintaining stable pressure, the controller activates the swirling flow field generating component to optimize gas mixing within the cavity. In one specific implementation, this swirling flow field generating component is the brushless vortex fan as described in claim 9. Simultaneously, the device's air inlet and outlet are connected to an external gas analyzer (such as a photosynthesis system) via a gas pipe, forming a complete measurement loop. The gas analyzer then begins analyzing the component concentrations in the circulating gas.

[0080] Step S4: Record the gas exchange data and perform the disassembly procedure after the measurement is completed.

[0081] In dynamic measurement mode, the external gas analyzer monitors and records the changes in carbon dioxide and water vapor concentrations in the gas flowing through the measurement chamber in real time. By calculating the rate of change of concentration per unit time, the photosynthetic rate or respiration rate of that plant stem segment, i.e., its carbon sequestration intensity, can be obtained. After the predetermined measurement time is completed and the data is recorded, the measurement ends. At this time, the controller executes the pre-disassembly preparation procedure. First, it controls the opening of the pressure relief valve to completely expel and contract the gas in the inflatable elastic seal, relieving its pressure on the plant stem. This is a crucial step to ensure safe and non-destructive disassembly. After the seal has fully contracted, the operator can release the two-stage locking mechanism and easily remove the split housing from the plant stem.

[0082] This invention, through the aforementioned methods and steps, particularly the introduction of automated airtightness self-checking and dynamic pressure maintenance based on hysteresis logic, provides a highly standardized, reliable, and plant-friendly in-situ measurement process. It not only simplifies field operations and reduces human error, but also significantly improves the accuracy and scientific value of plant stem carbon sequestration measurements by ensuring sealing stability and environmental controllability throughout the measurement process.

[0083] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. An in-situ measurement device for carbon sequestration in plant stems, comprising: A split housing with an air inlet and an air outlet; The split-type housing is used to fasten onto the plant stem, and a cavity for measurement is formed between the inner wall of the split-type housing and the plant stem; The feature is that the port of the split-type housing used to fasten the plant stem is provided with an adaptive dynamic sealing system; the adaptive dynamic sealing system includes: an inflatable elastic seal and a pressure regulating unit connected to the inflatable elastic seal via an air circuit; the pressure regulating unit is used to keep the internal pressure of the inflatable elastic seal constant within a set pressure threshold range.

2. The in-situ carbon sequestration measurement device for plant stems according to claim 1, characterized in that, The inflatable elastic seal has a flexible contact layer facing the plant stem and a rigid contact layer that forms a mechanical seal with the port of the split housing for fastening the plant stem.

3. The in-situ carbon sequestration measurement device for plant stems according to claim 1, characterized in that, The pressure regulating unit includes: a miniature air pump, a pressure sensor installed in the air delivery pipeline, a pressure relief valve, and a controller; the controller is electrically connected to the miniature air pump, the pressure sensor, and the pressure relief valve respectively.

4. The in-situ carbon sequestration measurement device for plant stems according to claim 2, characterized in that, The flexible contact layer has a different wall thickness than the rigid contact layer; The flexible contact layer is a first silicone layer with a Shore hardness of 10A-20A. The surface of the first silicone layer is uniformly distributed with micron-level hydrophobic protrusions of irregular texture for adhering to the surface of plant stems. The rigid contact layer is a second silicone layer with a Shore hardness of 40A-60A. The rigid contact layer and the first silicone layer are formed into an independent gas expansion cavity by a high-frequency hot pressing process. The rigid contact layer and the split shell are bonded together at the port for fastening the plant stem to form an airtight sealed connection.

5. The in-situ carbon sequestration measurement device for plant stems according to claim 3, characterized in that, The controller includes a pressure maintenance module; the maintenance module includes a hysteresis comparison circuit, the hysteresis comparison circuit being configured with a first voltage threshold corresponding to the lower limit of the pressure threshold and a second voltage threshold corresponding to the upper limit of the pressure threshold. The pressure maintenance module is configured to prevent high-frequency oscillations in the pneumatic circuit at critical pressure points. It only outputs a control signal to change the on / off state of the micro air pump or pressure relief valve when the voltage signal output by the air pressure sensor jumps out of the hysteresis range defined by the first voltage threshold and the second voltage threshold.

6. The in-situ carbon sequestration measurement device for plant stems according to claim 1, characterized in that, The joint surface of the split shell is sealed by a thermal response compensation sealing mechanism; the thermal response compensation sealing mechanism includes a shape memory alloy material with bidirectional memory effect, which is embedded in the sealing groove opened in the joint surface of the split shell, and is used to actively compensate for the gap caused by thermal expansion and contraction of the joint surface of the split shell when the ambient temperature changes.

7. The in-situ carbon sequestration measurement device for plant stems according to claim 6, characterized in that, The thermal response compensation sealing mechanism includes an elastic rubber matrix and a nickel-titanium shape memory alloy wire array embedded in the matrix. The nickel-titanium shape memory alloy wire array is heat-treated and configured to undergo an austenitic phase transformation when the ambient temperature rises to the phase transformation point, generating a restoring force that contracts axially or bends radially, driving the elastic rubber matrix to deform and fill the gaps caused by the thermal expansion of the split shell.

8. The in-situ carbon sequestration measurement device for plant stems according to claim 1, characterized in that, The split-type housing is made of a spectrally selective composite material; the composite material includes a transparent polymer substrate and a multilayer dielectric film deposited on the inner surface of the substrate by magnetron sputtering; the multilayer dielectric film is configured to have a transmittance of more than 90% for visible light with wavelengths of 400nm-700nm and a reflectance of more than 85% for infrared light with wavelengths of 700nm-2500nm.

9. The in-situ carbon sequestration measurement device for plant stems according to claim 1, characterized in that, The cavity used for measurement is equipped with a brushless vortex fan for generating a spiraling, uniform airflow; the brushless vortex fan is fixedly connected to the inner wall of one of the split housings.

10. A method for measuring carbon sequestration in plant stems, characterized in that, Includes the following steps: S1: Close the split shell to the outer periphery of the stem of the plant to be tested through a two-stage locking mechanism; S2: Perform airtightness self-test procedure: The controller controls the micro air pump to inflate the inflatable elastic seal to the upper limit of the damage threshold, then turns off the air pump and monitors the pressure drop within 30 seconds. If the pressure drop is less than the preset value, the seal is deemed qualified. S3: Enter dynamic measurement mode: The controller dynamically maintains the pressure inside the inflatable elastic seal between 1.0 kPa and 2.0 kPa according to the logic of the hysteresis comparison circuit. At this time, the swirling flow field generating component is activated and the external gas analyzer is connected. S4: Record gas exchange data, and after the measurement is completed, open the pressure relief valve to fully contract the inflatable elastic seal, and then open the split housing.

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