Soil pH detection method and device based on Raman spectroscopy

Abstract

The present invention relates to the technical field of soil detection, and specifically discloses a soil pH value detection method and device based on Raman spectroscopy. The device includes a detection body, wherein a detection execution unit is provided inside the detection body, and the detection execution unit uses laser to excite the Raman spectrum electrical signal of the soil sample solution. The detection execution unit includes: a sample cylinder, which is provided in the internal cavity of the detection body and is used to store the soil sample solution to be tested; a detection rod, which is vertically provided at the upper part of the sample cylinder, and the bottom end of the detection rod is provided with a detection end extending into the sample cylinder, a detection cavity is provided inside the detection end, and a spectrum detection component is provided inside the detection cavity. The spectrum detection component includes a Raman probe, an optical mechanism and a base plate; a plurality of through holes connected to the detection cavity are formed around the middle position of the outer peripheral surface of the detection end, and a filter is provided in the through holes, thereby achieving accurate and efficient detection of the soil pH value.

Description

Technical Field

[0001] The present invention relates to the technical field of soil detection, and specifically discloses a soil pH value detection method and device based on Raman spectroscopy. Background Art

[0002] Soil pH is a key parameter for measuring soil's physical and chemical properties, directly impacting crop growth and nutrient availability. Traditional detection methods, such as potentiometric methods, rely on contact measurements between a glass electrode and a reference electrode, which poses challenges such as easy electrode contamination and cumbersome maintenance. In recent years, optical detection technologies have gained increasing attention, with Raman spectroscopy, in particular, garnering attention due to its non-invasive nature and high molecular specificity.

[0003] Existing approaches have explored direct detection of soil particles through Raman spectroscopy, for example, using a fixed sample chamber coupled with an external light source to invert pH values ​​by collecting surface scattering spectra from soil particles. However, these methods require grinding, drying, and pressing soil samples into sheets, which involves complex pretreatment processes. Furthermore, solid particles can easily block or scatter light, resulting in a low signal-to-noise ratio and making it difficult to accurately extract pH-related characteristic peaks. Furthermore, the static sample chamber design lacks dynamic mixing, and uneven distribution of soil components can lead to measurement deviations, compromising detection sensitivity and stability. Summary of the Invention

[0004] The present invention aims to provide a soil pH detection method and device based on Raman spectroscopy to solve one of the above-mentioned technical problems existing in the prior art.

[0005] Specifically, the present invention is achieved through the following technical solutions:

[0006] A soil pH value detection device based on Raman spectroscopy includes a detection body, wherein a detection execution unit is provided inside the detection body, and the detection execution unit uses laser to excite the Raman spectrum electrical signal of the soil sample solution;

[0007] The detection execution unit includes: a sample cylinder, which is arranged in the internal cavity of the detection body and is used to store the soil sample solution to be tested; a detection rod, which is vertically arranged at the upper part of the sample cylinder, and the bottom end of the detection rod is provided with a detection end extending into the sample cylinder, a detection cavity is provided inside the detection end, and a spectrum detection component is provided inside the detection cavity, the spectrum detection component includes a Raman probe, an optical mechanism and a base plate, the Raman probe is vertically installed at the upper part of the detection cavity, the optical mechanism includes a laser transmitter and a laser receiver, the laser transmitter is installed at the bottom end of the Raman probe, the laser receiver is provided on the outside of the Raman probe, and the base plate is provided at the bottom of the detection cavity and directly opposite the position of the laser transmitter;

[0008] A plurality of through holes communicating with the detection cavity are arranged around the middle of the outer peripheral surface of the detection end, and filters are arranged in the through holes.

[0009] This solution prepares soil samples into a solution state for testing, completely abandoning the cumbersome pretreatment processes such as grinding, drying, and tableting in traditional methods. In other words, through the dynamic detection mechanism of soil sample solution and the integrated optical detection system, it overcomes the technical defects of traditional soil pH detection methods, effectively solves the problems of complex soil sample pretreatment, severe signal interference, and insufficient detection accuracy caused by uneven component distribution in existing technologies, and improves detection efficiency and stability.

[0010] Furthermore, a detection and analysis unit is further provided inside the detection body, and the detection and analysis unit includes a spectrometer electrically connected to the laser receiver, and the spectrometer is connected to an external processing device through a data interface;

[0011] In the above solution, the spectrometer is used to receive and analyze the Raman spectrum electrical signal, and then transmit the Raman spectrum electrical signal to the external processing device through the data interface, so that the external processing device processes the Raman spectrum electrical signal and generates a pH value detection result.

[0012] Specifically, a transparent partition is provided inside the detection cavity and above the through hole. The transparent partition is used to divide the detection cavity into a closed cavity and an excitation cavity from top to bottom. The Raman probe and the optical mechanism are located in the closed cavity, and the base plate is located in the excitation cavity.

[0013] In the above scheme, by setting up a transparent partition and placing the Raman probe and optical structure in a closed cavity, the moisture, dust and other pollutants in the external soil solution can be effectively isolated, preventing the optical components from getting damp or contaminated, and ensuring long-term detection stability. The transparent partition can ensure the efficient penetration of the laser and will not affect the collection of Raman signals.

[0014] Furthermore, an optical lens group is provided on the upper part of the transparent partition, and the optical lens group includes a first focusing lens and a second focusing lens. The first focusing lens is provided at the transmitting end position of the laser transmitter, and the second focusing lens is provided at the receiving end position of the laser receiver.

[0015] Based on the above-mentioned arrangement of the first focusing lens and the second focusing lens, the laser optical path is optimized, and high energy density incident laser light and maximum capture of weak Raman signals are guaranteed, thereby ensuring detection stability and improving detection sensitivity.

[0016] Preferably, a mounting plate for mounting a laser receiver is fixedly provided on the outside of the Raman probe, the bottom surface of the mounting plate is recessed upward and is in the shape of an inverted bowl, a plurality of laser receivers are provided, and an array of the plurality of laser receivers is attached to the bottom surface of the mounting plate.

[0017] Through the above-mentioned mounting plate, the geometric curvature of the bottom allows multiple laser receivers to be arranged in an array to expand the receiving field of view. At the same time, the reflection effect of the bowl-shaped structure of the mounting plate is used to converge the edge scattered light that may escape to the receiver for a second time, thereby improving the integrity of the Raman spectrum electrical signal acquisition and facilitating subsequent detection.

[0018] Furthermore, the top of the sample cylinder is closed, and a feed pipe and a discharge pipe extending to the outside of the detection body are connected to both sides of the sample cylinder, which facilitate the filling and discharge of the soil sample solution.

[0019] Further preferably, a bearing sealing ring is provided at a position where the outer portion of the detection end and the top end of the sample tube penetrate each other, the detection end is rotationally matched with the sample tube through the bearing sealing ring, and the detection end is rotationally connected to the detection rod;

[0020] A driving device is also provided at the top end of the sample tube. The output end of the driving device is connected to the detection end via a transmission mechanism, and the detection end is driven to rotate by the driving device.

[0021] It should be noted that the measurement results of Raman spectroscopy are easily affected by sample heterogeneity. For example, uneven distribution of soil particles and local concentration differences will cause deviations in the final detection results, making it impossible to correctly measure the soil pH value. Based on this, the above technical solution sets a bearing sealing ring at the penetration position between the detection end and the sample barrel, so that the detection end can be rotated with the sample barrel through the bearing sealing ring, and combines with the driving device to drive the detection end to rotate through the transmission mechanism. Its purpose is to provide a dynamic mixing driving force for the soil sample solution through the rotation of the detection end, improve the uniformity of the distribution of soil particle components in the soil sample solution, thereby reducing the measurement deviation caused by uneven soil composition and improving the detection sensitivity and stability.

[0022] More preferably, a stirring member is provided at the bottom of the detection end at a position corresponding to the through hole.

[0023] This solution further incorporates a stirring element at the bottom of the detection end, corresponding to the through-hole. This design aims to enhance the dynamic mixing of the soil sample solution through the synergistic effect of mechanical stirring and detection end rotation, thereby more effectively eliminating the sedimentation of particulate matter in the solution or localized excessive concentrations, ensuring the uniformity and representativeness of the sample composition during Raman spectroscopy testing and ensuring the accuracy of the test results.

[0024] Furthermore, a layer of noble metal nanoparticles is coated on the upper portion of the base plate, and nano-spiral grooves are staggered on the surface of the noble metal nanoparticles layer.

[0025] In the above scheme, by coating a layer of precious metal nanoparticles on the surface of the substrate and opening staggered nano-spiral grooves, its core purpose is to utilize the surface-enhanced Raman scattering (SERS) effect to significantly improve the sensitivity and anti-interference ability of soil pH detection. At the same time, the fluid guidance effect of the nanostructure is used to optimize the interaction efficiency between the sample and the laser, so as to further improve the accuracy and sensitivity of detection.

[0026] The soil pH detection method based on Raman spectroscopy, according to the soil pH detection device based on Raman spectroscopy proposed above, specifically, the method includes the following steps:

[0027] Step 1: Mix the soil sample to be tested with a solvent to prepare a soil sample solution, and add the soil sample solution into the sample cylinder through a feeding tube;

[0028] Step 2: While the soil sample solution is being added, the driving device is started to rotate the detection end, which drives the stirring element to stir the soil sample solution entering the sample tube to form a uniformly dispersed system. At the same time, as the detection end and the stirring element rotate, the soil sample solution is forced to pass through the through hole into the excitation cavity of the detection cavity;

[0029] Step 3: After the soil sample solution enters the excitation chamber, the driving device is turned off to stop the rotation of the detection end, and the discharge pipe is opened to discharge the remaining soil sample solution in the sample tube. The laser emitter is then controlled to emit laser light. After being focused by the first focusing lens, the laser light passes through the transparent partition and is emitted to the soil sample solution in the holding tank in the excitation chamber. The soil particles in the soil sample solution interact with the laser light to generate Raman scattered light. The Raman scattered light passes through the transparent partition and is focused by the second focusing lens. It is received by the laser receiver located around the Raman probe and transmitted to the spectrometer.

[0030] Step 4: The spectrometer analyzes and processes the received Raman spectrum electrical signal and outputs it to an external processing device. The external processing device calculates the pH value of the soil sample solution based on a pre-established relationship model between the Raman spectrum and the soil pH value.

[0031] The detection method based on the above scheme forms a highly synergistic effect with the hardware structure design, and utilizes the multi-dimensional coupling of dynamic mixing, optical path optimization and signal enhancement to significantly improve the accuracy and reliability of soil pH detection.

[0032] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0033] 1. The present invention provides a sample tube and a detection rod with an integrated detection end, allowing soil samples to be directly detected in the form of a solution. The molecular diffusion characteristics of the solution sample reduce the risk of light path obstruction and effectively reduce the diffuse reflection interference of solid soil particles on the laser. This allows the laser to directly penetrate the soil sample solution, avoiding the obstruction of the light path by solid particles, thereby improving the signal-to-noise ratio of the Raman signal.

[0034] 2. This solution achieves the dual functions of dynamic circulation of the soil sample solution to be tested and solid particle filtration through the through-hole and filter structure arranged in a ring around the periphery of the detection end. When the soil sample solution enters the detection cavity through the through-hole, the soil sample solution can spontaneously undergo dynamic mixing through the flow to ensure that the soil components in the solution are evenly distributed. The filter can also simultaneously filter out undissolved larger impurity particles (such as sand particles and organic debris) to prevent them from blocking the light path or generating nonspecific scattering after entering the detection cavity, thereby avoiding interference with the laser by these impurity particles.

[0035] 3. The detection cavity of this solution is equipped with a reflective optical path consisting of a spectral detection component composed of a laser transmitter, a receiver, and a substrate. After the laser transmitter generates laser light and vertically incidents it into the soil sample solution, the substrate plate excites the Raman scattering signal of the soil solution. The signal is then reflected and received by the laser receiver, forming a closed-loop "excitation-scattering-collection" optical path, thereby enhancing the Raman signal intensity and achieving rapid and accurate detection of soil pH value.

[0036] 4. The present invention uses a rotating detection end in conjunction with a stirring element. Through the synergistic effect of mechanical stirring and rotation of the detection end, the dynamic mixing effect of the soil sample solution is enhanced, thereby more efficiently eliminating the sedimentation of particulate matter in the solution or the phenomenon of local excessive concentration, ensuring the uniformity and representativeness of the sample composition during Raman spectroscopy detection, and ensuring the accuracy of the test results;

[0037] 5. The present invention provides a cleaning piece at the through-hole position and links it with the stirring piece at the bottom. During the stirring process, when the stirring rod rotates, the stirring blades stir and push the soil sample solution, which simultaneously drives the rotating roller of the cleaning piece to rotate, so that the cleaning brush scrapes the filter in real time, thereby cleaning the filter in the through-hole, preventing particulate impurities in the soil sample solution from adhering to the filter and causing blockage, thereby further ensuring that the evenly dispersed soil sample solution smoothly enters the excitation chamber, thereby achieving high-precision detection results and improving the use effect of the detection device. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0039] Figure 1 This is a schematic diagram of the overall structure of embodiment 1 of the present invention;

[0040] Figure 2 This is a partial structural diagram of the mounting plate of the present invention, intended to illustrate the mounting plate and the laser receiver;

[0041] Figure 3 This is a bottom-up structural diagram of the mounting plate of the present invention, intended to illustrate the laser receiver array arrangement;

[0042] Figure 4 This is a schematic diagram of the detection end structure of the present invention, which is intended to illustrate the drive device and transmission mechanism;

[0043] Figure 5 This is a schematic diagram of a preferred structure of a receiving tank according to embodiment 1 of the present invention;

[0044] Figure 6 This is a flow chart of the method of embodiment 2 of the present invention;

[0045] Figure 7 Schematic diagram of the structure of the cleaning member of Example 3 of the present invention;

[0046] Figure 8 This is a schematic diagram of the detection end structure from above of the present invention, which is intended to show the state of the cleaning part;

[0047] Figure 9 Schematic diagram of the preferred structure of the stirring blade in Example 3 of the present invention.

[0048] The reference numerals represent: 1. detection body; 21. sample tube; 22. detection rod; 23. detection end; 231. Raman probe; 2321. laser emitter; 2322. laser receiver; 233. base plate; 234. through hole; 2341. filter; 235. transparent partition; 236. first focusing lens; 237. second focusing lens; 24. detection chamber; 241. sealed chamber; 242. excitation chamber; 2421. receiving tank; 25. driving device; 26. transmission mechanism; 261. driving gear; 262. transmission ring gear; 27. stirring member; 271. stirring rod; 272. stirring blade; 28. cleaning member; 281. rotating shaft; 282. rotating roller; 283. cleaning brush; 3. spectrometer; 4. feed pipe; 5. discharge pipe; 6. mounting plate. DETAILED DESCRIPTION

[0049] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the examples and accompanying drawings. The exemplary embodiments of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention. It should be noted that the present invention is already in the actual development and use stage.

[0050] Example 1;

[0051] See also Figures 1 to 4 As shown, this embodiment discloses a soil pH value detection device based on Raman spectroscopy, including a detection body 1, wherein a detection execution unit is provided inside the detection body 1, and the detection execution unit uses laser to excite the Raman spectrum electrical signal of the soil sample solution;

[0052] The detection execution unit includes: a sample cylinder 21, which is arranged in the internal cavity of the detection body 1 and is used to store the soil sample solution to be tested; a detection rod 22, which is vertically arranged at the upper part of the sample cylinder 21, and the bottom end of the detection rod 22 is provided with a detection end 23 extending into the sample cylinder 21, and a detection cavity 24 is provided inside the detection end 23, and a spectrum detection component is provided inside the detection cavity 24, and the spectrum detection component includes a Raman probe 231, an optical mechanism and a base plate 233, the Raman probe 231 is vertically installed at the upper part of the detection cavity 24, the optical mechanism includes a laser emitter 2321 and a laser receiver 2322, the laser emitter 2321 is installed at the bottom end of the Raman probe 231, the laser receiver 2322 is provided on the outside of the Raman probe 231, and the base plate 233 is provided at the bottom of the detection cavity 24 and directly facing the laser emitter 2321;

[0053] A plurality of through holes 234 communicating with the detection cavity 24 are formed around the middle of the outer circumference of the detection end 23 , and a filter 2341 is provided in each of the through holes 234 .

[0054] In the above embodiment, the present application provides a sample tube 21 and a detection rod 22 with an integrated detection end 23, so that the soil sample can be directly detected in the form of a solution. The molecular diffusion characteristics of the solution sample reduce the risk of light path obstruction, effectively reducing the diffuse reflection interference of solid soil particles on the laser, allowing the laser to directly penetrate the soil sample solution, avoiding the obstruction of the light path by solid particles, thereby improving the signal-to-noise ratio of the Raman signal.

[0055] In addition, the present application realizes the dual functions of dynamic circulation of the soil sample solution to be tested and solid particle filtration through the structure of the through holes 234 and the filter 2341 arranged in an annular manner on the periphery of the detection end 23. When the soil sample solution enters the detection cavity 24 through the through holes 234, the soil sample solution can spontaneously undergo dynamic mixing through the flow to ensure that the soil components in the solution are evenly distributed, while the filter 2341 can simultaneously filter out undissolved larger impurity particles (such as sand particles and organic debris) to prevent them from blocking the light path or generating nonspecific scattering after entering the detection cavity 24, thereby avoiding interference of the impurity particles with the laser.

[0056] At the same time, a reflective optical path composed of a spectral detection component consisting of a laser emitter 2321, a receiver and a base plate 233 is set in the detection cavity 24. After the laser generated by the laser emitter 2321 is vertically incident on the soil sample solution, the Raman scattering signal of the soil solution is excited and reflected by the base plate 233, and then received by the laser receiver 2322 to form an "excitation-scattering-collection" closed-loop optical path, thereby enhancing the Raman signal intensity and realizing rapid and accurate detection of soil pH value.

[0057] Accordingly, in this application, by making the soil sample into a solution for testing, the cumbersome pretreatment process of grinding, drying, and tableting in the traditional method is completely abandoned. That is to say, through the dynamic detection mechanism of the soil sample solution and the integrated optical detection system, the technical defects of the traditional soil pH detection method are overcome, and the problems of complex pretreatment, serious signal interference, and insufficient detection accuracy caused by uneven component distribution in the existing technology are effectively solved, thereby improving the detection efficiency and stability.

[0058] It should be noted that laser emitter 2321 and laser receiver 2322 are prior art and readily available to those skilled in the art through publicly available sources. This application does not further define or specifically describe these technologies. For example, laser emitter 2321 may utilize a common semiconductor laser to generate a laser beam of a specific wavelength (e.g., 532 nm or 785 nm suitable for Raman spectroscopy detection); while laser receiver 2322 utilizes a photodetector, such as a silicon-based photodiode or an avalanche photodiode, to convert the received weak Raman scattered light signal into a corresponding Raman spectroscopy electrical signal.

[0059] Based on the above embodiment, further, the detection body 1 is further provided with a detection and analysis unit. Figure 1 It has been shown that the detection and analysis unit includes a spectrometer 3 electrically connected to the laser receiver 2322, and the spectrometer 3 is connected to an external processing device through a data interface;

[0060] In a specific implementation, the spectrometer 3 is used to receive and analyze the Raman spectrum electrical signal, and then transmit the Raman spectrum electrical signal to an external processing device through a data interface, so that the external processing device processes the Raman spectrum electrical signal and generates a pH value detection result.

[0061] Exemplarily, the spectrometer 3 may be a compact fiber optic spectrometer 3, which forms an electrical signal transmission path with the laser receiver 2322 through a hardware circuit, and uses a standard data interface (such as USB3.0, Ethernet interface or fiber optic data interface) to establish a communication connection with an external processing device (such as a computer, a portable industrial computer or other mobile terminal, etc.), to ensure that the Raman spectrum electrical signal is directly introduced into the detector array inside the spectrometer 3, and the weak Raman spectrum electrical signal is converted into a digital signal. The original spectrum electrical signal is baseline corrected and noise filtered based on a preset wavelength calibration algorithm, and the characteristic spectral region related to the pH value (such as the hydroxyl vibration peak, the hydrated ion characteristic peak, etc.) is preliminarily extracted, and then output to the processing device through the data interface, and based on the pre-processing of the external processing device The onboard spectral analysis software can model and analyze the input Raman spectral data based on chemometric algorithms such as partial least squares (PLS) and artificial neural networks (ANN). For example, it can extract the main components in the spectral data through principal component analysis (PCA), eliminate the interference of background noise and irrelevant signals, and then match the characteristic spectral parameters with the pre-established soil pH correction model. Ultimately, it generates quantitative pH value detection results and displays them through a real-time visual interface, thereby forming a closed loop for the entire signal processing process. Starting from the capture of Raman scattered light by laser receiver 2322, through the photoelectric conversion and preliminary analysis by spectrometer 3, to the intelligent algorithm processing of external processing equipment, it finally achieves the precise conversion from spectral signal to pH value detection result.

[0062] It should also be noted that the above-mentioned explanation of the principles of the spectrometer 3 and the processing equipment is only an example, which is essentially the existing technology. Those skilled in the art can obtain the basic principles of Raman spectroscopy detection through public channels. Therefore, this application does not specifically limit or further explain the specific excitation parameters, signal processing flow and detection principles of its Raman spectrum. It is not within the scope of protection of this application. This application only aims at improving the structure of the detection device.

[0063] As a specific implementation method, Figure 1 As shown, a transparent partition 235 is provided inside the detection cavity 24 and above the through hole 234. The transparent partition 235 is used to divide the detection cavity 24 into a closed cavity 241 and an excitation cavity 242 from top to bottom. The Raman probe 231 and the optical mechanism are located in the closed cavity 241, and the base plate 233 is located in the excitation cavity 242.

[0064] As an example, the transparent partition 235 is made of quartz glass or polycarbonate, with a light transmittance of ≥97%, and a sealing ring is provided on the edge of the transparent partition 235, which is fixed to the inside of the detection cavity 24 by bolts.

[0065] In the above embodiment, by providing a transparent partition 235 and placing the Raman probe 231 and the optical mechanism in the closed chamber 241, moisture, dust and other pollutants in the external soil solution can be effectively isolated, the optical components can be prevented from being damp or contaminated, and long-term detection stability can be ensured. The transparent partition 235 can ensure efficient penetration of the laser and will not affect the collection of the Raman signal.

[0066] Specifically, the excitation cavity 242 is connected to the soil solution in the sample cylinder 21 via circumferentially distributed through-holes 234, forming an independent signal excitation region. Furthermore, the base plate 233 is fixed to the bottom of the excitation cavity 242, maintaining a certain optical distance from the lower surface of the transparent partition 235. This ensures that the laser light, after passing through the sealed cavity 241 and the transparent partition 235, forms a stable focused light spot in the excitation cavity 242.

[0067] Specifically, the laser emitted by the laser emitter 2321 enters the excitation cavity 242 through the transparent partition 235 and irradiates the solution on the base plate 233, thereby exciting the H⁺, OH⁻ plasma and water molecules in the soil solution to generate Raman scattered light. At the same time, the Raman scattered light signal is reflected by the base plate 233 and then passes upward through the transparent partition 235. It is received by the laser receiver 2322 in the closed cavity 241, forming a coaxial optical path of "excitation light downward-scattered light upward". In this way, the physical isolation characteristics of the transparent partition 235 are utilized to ensure the attenuation-free transmission of the optical signal, while constructing a dust-proof and liquid-proof enclosed space, ensuring the normal operation of the detection.

[0068] As a further possible embodiment of the above embodiment, Figure 1 As shown in FIG, an optical lens group is further provided on the upper portion of the transparent partition 235, and the optical lens group includes a first focusing lens 236 and a second focusing lens 237. The first focusing lens 236 is provided at the transmitting end position of the laser transmitter 2321, and the second focusing lens 237 is provided at the receiving end position of the laser receiver 2322.

[0069] Based on the first focusing lens 236 and the second focusing lens 237 of the above embodiment, the laser optical path is optimized, and high energy density incident laser light and maximum capture of weak Raman signals are guaranteed, thereby ensuring detection stability and improving detection sensitivity.

[0070] As a further preferred example, the first focusing lens 236 is a plano-convex lens, which effectively reduces thermal deformation and energy loss during laser transmission. At the same time, its plano-convex structure (the flat side is close to the laser) can accurately control the divergence angle of the laser beam, ensuring the uniformity and accuracy of the laser incident spot. The first focusing lens 236 is made of fused quartz and is directly connected to the laser emitter 2321 through a bracket.

[0071] The second focusing lens 237 is a biconvex lens, which is fixedly mounted on the outside of the Raman probe 231 and corresponds to the laser receiver 2322. Its surface is also coated with a Raman-enhanced anti-reflection film. The second focusing lens 237 includes a silicon dioxide layer, a silver noble metal nanoparticle layer and a magnesium fluoride protective layer deposited from the inside to the outside, which helps to enhance the signal strength of the Raman scattered light and realizes efficient collection of scattered light to ensure the sensitivity of subsequent detection.

[0072] As a preferred embodiment, further Figure 2 and Figure 3 As shown, a mounting plate 6 for mounting a laser receiver 2322 is fixedly mounted on the outside of the Raman probe 231. The bottom surface of the mounting plate 6 is recessed upward in an inverted bowl shape. There are multiple laser receivers 2322, and an array of multiple laser receivers 2322 is attached to the bottom surface of the mounting plate 6.

[0073] Through the above-mentioned installation plate 6, the geometric curvature of the bottom allows multiple laser receivers 2322 to be arranged in an array to expand the receiving field of view. At the same time, the reflection effect of the bowl-shaped structure of the installation plate 6 is utilized to converge the edge scattered light that may escape to the receiver for a second time, thereby improving the integrity of the Raman spectrum electrical signal acquisition, which is beneficial for subsequent detection.

[0074] Exemplarily, multiple laser receivers 2322 are arranged in a circular array, and the center distance between adjacent laser receivers 2322 is 10-15 mm, thereby expanding the receiving field angle of the laser receiver 2322 and optimizing the optical path focusing, thereby improving its Raman scattering spectral signal reception efficiency.

[0075] As a further supplement to the above embodiment, Figure 1 As shown in the figure, the top of the sample cylinder 21 is closed, and a feed pipe 4 and a discharge pipe 5 extending to the outside of the detection body 1 are connected to both sides of the sample cylinder 21. The provision of the feed pipe 4 and the discharge pipe 5 facilitates the filling and discharge of the soil sample solution.

[0076] In a further preferred embodiment, a bearing sealing ring is provided at a position where the outer portion of the detection end 23 and the top end of the sample tube 21 penetrate each other, and the detection end 23 is rotationally engaged with the sample tube 21 through the bearing sealing ring, and the detection end 23 is rotationally connected to the detection rod 22;

[0077] A driving device 25 is further provided at the top end of the sample tube 21 . The output end of the driving device 25 is connected to the detection end 23 via a transmission mechanism 26 , and the detection end 23 is driven to rotate by the driving device 25 .

[0078] It should be understood that the measurement results of Raman spectroscopy are easily affected by sample heterogeneity. For example, uneven distribution of soil particles and local concentration differences will lead to deviations in the final test results, making it impossible to accurately measure the soil pH value. Based on this problem, the present application sets a bearing sealing ring at the penetration position of the detection end 23 and the sample tube 21, so that the detection end 23 can achieve rotational cooperation with the sample tube 21 through the bearing sealing ring, and combines the driving device 25 to drive the detection end 23 to rotate through the transmission mechanism 26. The purpose is to provide a dynamic mixing driving force for the soil sample solution through the rotation of the detection end 23, improve the uniformity of the distribution of components in the solution, thereby reducing the measurement deviation caused by uneven soil components and improving the detection sensitivity and stability.

[0079] Furthermore, the present invention differs from the prior art in that the rotation of the detection end 23 is used to promote the flow of the soil sample solution, thereby ensuring uniform composition of the soil sample solution to be tested, and thus ensuring sample consistency during Raman spectroscopy signal acquisition. Furthermore, the design of the bearing sealing ring effectively prevents solution leakage while ensuring the rotation of the detection end 23, thereby ensuring the sealing and reliability of the device. Therefore, the present invention solves the problem in the prior art that the static sample chamber design cannot achieve dynamic mixing, thereby affecting detection accuracy. It optimizes the quality of the Raman spectroscopy signal and improves the accuracy and repeatability of pH detection.

[0080] Specifically, the detection end 23 and the detection rod 22 are connected via a high-precision bearing to ensure smooth rotation between the detection end 23 and the detection rod 22 .

[0081] For example, in the present application, the driving device 25 is mainly used for power output. Therefore, for the driving device 25, technicians in the relevant field can obtain the corresponding driving device 25 for providing power output through public channels for use in the present application. For the present application, it is preferably a motor. As for the transmission mechanism 26, it is mainly used to transmit the power output of the driving device 25 to the detection end 23 to realize the rotation of the detection end 23. Therefore, as the transmission mechanism 26 for power transmission, those skilled in the art can also obtain it through relevant public channels. In the present application, the transmission mechanism 26 is preferably a gear transmission, which includes a driving gear 261 installed at the output end of the motor, and a driven gear ring fixedly sleeved on the outside of the detection end 23 and meshing with the driving gear 261, as shown in FIG. Figure 4 and Figure 5 Then, the motor drives the driving gear 261 to rotate, which in turn drives the transmission ring gear 262 to rotate, thereby realizing the rotation of the detection end 23.

[0082] More preferably, see Figure 1As shown, a plurality of stirring members 27 are further provided at the bottom of the detection end 23 at positions corresponding to the through holes 234 .

[0083] This solution further provides a stirring element 27, the purpose of which is to enhance the dynamic mixing effect of the soil sample solution through the synergistic effect of mechanical stirring and the rotation of the detection end 23, thereby more efficiently eliminating the sedimentation of particles in the solution or the phenomenon of excessive local concentration, ensuring the uniformity and representativeness of the sample components during Raman spectroscopy detection, and ensuring the accuracy of the detection results; for example, specifically as follows Figure 5 As shown, the stirring member 27 includes a stirring rod 271 and stirring blades 272. The stirring rod 271 is connected to the detection end 23 via a rotating drum. The stirring rod 271 is rotatable within the rotating drum, with its bottom end protruding from the lower portion of the rotating drum. A plurality of stirring blades 272 are arranged in an array around the rotating bottom end. When the detection end 23 rotates, it drives the stirring member 27 to rotate within the soil sample solution, thereby stirring the soil sample solution. (It should be noted that this stirring is achieved by the stirring member 27 following the rotation of the detection end 23, which generates a large vortex in the soil sample solution.) As the stirring member 27 rotates, the stirring blades 272 collide with the vortex in the soil sample solution, generating a certain amount of thrust on the stirring blades 272, causing the stirring blades 272 to drive the stirring rod 271 to rotate within the rotating drum. The rotation of the stirring rod 271 and stirring blades 272 further promotes stirring of the soil sample solution.

[0084] It should be understood that compared with the mixing method relying on static diffusion or simple rotation in the prior art, the present application can achieve double stirring of the soil sample solution (or the combined action of stirring and disturbance) through the stirring action of the circumferential rotation of the stirring element 27 and the active turbulence effect generated by the rotation, thereby significantly improving the convection intensity inside the solution, reducing the fluctuation of the Raman spectrum electrical signal caused by uneven particle distribution or local enrichment of pH-sensitive molecules (such as H⁺, Al³⁺, etc.), and thus improving the sensitivity and accuracy of pH detection. At the same time, the combination of the stirring element 27 and the filter 2341 (the filter 2341 at the through hole 234 filters large particles of soil impurities) further optimizes the light path transmittance, reduces the interference of scattering noise on Raman characteristic peaks (such as vibration signals of functional groups such as silicate and carbonate related to soil pH), solves the measurement deviation problem caused by uneven distribution of soil samples in traditional Raman detection, and realizes rapid and accurate detection of soil pH.

[0085] Furthermore, a layer of noble metal nanoparticles is coated on the upper portion of the base plate 233 , and nano-spiral grooves are staggered on the surface of the noble metal nanoparticles layer.

[0086] By coating the surface of the substrate 233 with a layer of precious metal nanoparticles and providing staggered nano-spiral grooves, the core purpose is to utilize the surface-enhanced Raman scattering (SERS) effect to significantly improve the sensitivity and anti-interference ability of soil pH detection, while optimizing the interaction efficiency between the soil sample solution and the laser through the fluid guidance effect of the nanoparticle layer and the nano-spiral groove structure.

[0087] Specifically, the precious metal nanoparticle layer is preferably gold or silver nanoparticles, which can enhance the Raman signal through the localized surface plasmon resonance effect, thereby reducing the minimum limit of pH detection. The nanospiral groove can break the symmetric pattern of the traditional nanoparticle layer, so that the surface plasmon presents a non-uniform enhanced distribution, and can guide the solution to form a vortex flow when entering the holding groove 2421 in the excitation cavity, thereby promoting full contact between pH-sensitive molecules and the active sites of the nanoparticles, reducing the interference of bubble retention and particle sedimentation on the signal, and ensuring the stable collection of Raman characteristic peaks (such as symmetric / asymmetric stretching vibration peaks related to pH), so as to further improve the accuracy and sensitivity of detection.

[0088] As a preferred embodiment of the above-mentioned method, as shown in the figure, the bottom of the excitation cavity 242 is recessed downward to form a hemispherical receiving groove 2421, and the receiving groove 2421 transitions to the through hole 234 in an arc shape, and the base plate 233 is parallelly attached to the receiving groove 2421, so that the laser forms an omnidirectional reflection focusing effect in the soil sample solution in the receiving groove 2421, that is, the laser beam is evenly covered with the precious metal nanoparticle layer of the base plate 233 attached in the groove after multiple reflections, thereby avoiding the energy edge loss of the traditional planar substrate, and further enhancing the intensity of the Raman spectrum scattered light, so that it can be captured and received by the laser receiver 2322 located at the bowl-shaped bottom of the mounting plate 6, thereby facilitating the candidate precision detection equipment, so that the detection equipment can detect more efficiently and accurately.

[0089] Example 2;

[0090] See also Figure 6 This embodiment is based on the soil pH value detection device based on Raman spectroscopy proposed in Example 1. On this basis, a soil pH value detection method based on Raman spectroscopy is proposed. Specifically, the method includes the following steps:

[0091] Step 1: Mix the soil sample to be tested with a solvent to prepare a soil sample solution, and add the soil sample solution into the sample cylinder 21 through the feeding pipe 4;

[0092] Step 2: While the soil sample solution is being added, the driving device 25 is activated to rotate the detection end 23. The detection end 23 drives the stirring member 27 to stir the soil sample solution entering the sample cylinder 21 to form a uniform dispersion system. At the same time, as the detection end 23 and the stirring member 27 rotate, the soil sample solution is forced to enter the excitation chamber 242 of the detection chamber 24 through the through hole 234.

[0093] Step 3: After the soil sample solution enters the excitation chamber 242, the driving device 25 is turned off to stop the rotation of the detection end 23, and the discharge pipe 5 is opened to discharge the remaining soil sample solution in the sample tube 21. The laser emitter 2321 is then controlled to emit a laser. After being focused by the first focusing lens, the laser passes through the transparent partition 235 and is emitted to the soil sample solution in the receiving tank 2421 in the excitation chamber. The soil particles in the soil sample solution interact with the laser to generate Raman scattered light. The Raman scattered light passes through the transparent partition 235 and is then focused by the second focusing lens. It is then received by the laser receiver 2322 located around the Raman probe 231 and transmitted to the spectrometer 3.

[0094] In step 4, the spectrometer 3 analyzes and processes the received Raman spectrum electrical signal and outputs it to an external processing device. The external processing device calculates the pH value of the soil sample solution based on a pre-established relationship model between the Raman spectrum and the soil pH value.

[0095] The detection method based on the above scheme forms a highly synergistic effect with the hardware structure design, and utilizes the multi-dimensional coupling of dynamic mixing, optical path optimization and signal enhancement to significantly improve the accuracy and reliability of soil pH detection. Further, in step 1 of this method, the soil is prepared as a solution and injected into the sample tube 21, which directly avoids the problems of optical path obstruction and complex pre-processing in traditional solid particle detection; and in step 2, the detection end 23 is rotated and the stirring member 27 is disturbed by the driving device 25, combined with the design of the through hole 234 filter 2341, to achieve uniform dispersion of the soil solution and filtration of impurities, ensure that the sample entering the excitation cavity 242 has consistent composition, and reduce measurement deviations caused by particle sedimentation or uneven distribution; in step 3, the hemispherical receiving tank 2421 uses the geometric focusing effect to focus the laser energy. The nano-spiral groove structure is concentrated on the surface of the noble metal nanoparticle layer, guiding the solution to form a vortex flow, promoting full contact between pH-sensitive molecules such as H⁺ and the active sites of the nanoparticles. At the same time, the transparent partition 235 and the double lens group design optimize the optical transmission efficiency, thereby enhancing the Raman scattering signal intensity. Finally, step 4 uses the pre-built spectrum-pH model analysis, combined with the SERS enhancement effect and the signal stability brought by dynamic mixing, to ultimately achieve high-precision, interference-resistant rapid detection of pH values, solving existing technical problems such as low signal-to-noise ratio, poor repeatability and high detection limit in existing technologies.

[0096] As a further supplement to the above embodiments, Figure 6 As shown in the figure, after the pH value of the soil sample solution is calculated in step 4, step 5 is also included. Specifically, after the soil sample solution in the sample cylinder 21 is discharged through the discharge pipe 5, the driving device 25 is started again to drive the detection end 23 to rotate again, so as to use centrifugal force to throw the sample solution remaining in the excitation chamber 242 out of the holding tank 2421 and completely discharge it through the discharge pipe 5.

[0097] In summary, the present application not only realizes the dynamic sampling required for traditional Raman spectroscopy detection and improves the detection sensitivity and stability of soil pH value through the optimized design of the dynamic rotation function of the detection end 23, but also further realizes the self-cleaning of the detection equipment. That is, after the detection is completed, by starting the driving device 25, it drives the detection end 23 to rotate again, so as to use centrifugal force to direct the sample solution (such as soil suspension) remaining in the excitation cavity 242 through the arc transition between the hemispherical holding tank 2421 and the pupil, thereby reducing the liquid adsorption on the surface of the precious metal nanoparticle layer, effectively solving the cross-contamination problem of traditional static detection devices, and thus improving the service life of the detection device.

[0098] Example 3;

[0099] See also Figures 7 to 9 This embodiment is based on the soil pH detection device based on Raman spectroscopy proposed in Example 1. On this basis, it is proposed that compared with Example 1, its difference is that:

[0100] A cleaning member 28 is further provided at the position of the plurality of through holes 234, and the bottom ends of the plurality of cleaning members 28 are connected to the stirring member 27, each of the cleaning members 28 includes a rotating shaft 281 whose top end is connected to the detection end 23 through a rotating ring that rotates together, a rotating roller 282 fixedly sleeved on the outside of the rotating shaft 281, and a cleaning brush 283 that contacts the filter 2341 in the through hole 234 is uniformly distributed on the outer surface of the rotating roller 282, the bottom end of the rotating shaft 281 is connected to the top of the stirring rod 271, and Figure 7 and Figure 8 It has been shown in .

[0101] Accordingly, by arranging a cleaning piece 28 at the position of the through hole 234 and linking it with the stirring piece 27 at the bottom, it is achieved that during the stirring process, when the stirring rod 271 rotates, the soil sample solution is stirred and pushed by the stirring blade 272, and the rotating roller 282 of the cleaning piece 28 is synchronously driven to rotate, so that the cleaning brush 283 scrapes the filter 2341 in real time, and then cleans the filter 2341 in the through hole 234, avoiding particulate impurities in the soil sample solution adhering to the filter 2341 and causing blockage, thereby further ensuring that the evenly dispersed soil sample solution smoothly enters the excitation cavity 242, so as to achieve high precision of the detection results and improve the use effect of the detection device.

[0102] As a further preferred embodiment, Figure 9 As shown, during the rotation of the plurality of stirring blades 272 , a concave groove is formed on the side thereof facing the soil sample solution.

[0103] Accordingly, during the rotation of the stirring blade 272, the recessed groove structure can enhance the fluid shear force and accelerate the breakage of the agglomerates, ensuring that the soil sample solution forms a uniform dispersion system in a short time. At the same time, a large rotational torque is generated during rotation, which facilitates the rapid driving of the rotating roller 282 and helps to push the sample solution to accelerate through the through hole 234 into the excitation chamber 242.

[0104] The above specific implementation methods further illustrate the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific implementation methods of the present invention. The specific selection and related material process parameters are only used to explain the present invention and are not used to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

[0105] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are schematic diagrams, which serve only to match the contents disclosed in the specification for understanding and reading by those familiar with this technology, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modification of the structure, change in the proportional relationship, or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the efficacy and purpose that can be achieved by the present invention. At the same time, terms such as "upper", "lower", "left", "right", "middle", etc. quoted in this specification are only for the convenience of description and are not intended to limit the scope of the implementation of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

Claims

1. A soil pH detection device based on Raman spectroscopy, comprising a detection body (1), characterized in that: A detection execution unit is provided inside the detection body (1), and the detection execution unit comprises: A sample cylinder (21), the sample cylinder (21) being arranged in the internal cavity of the detection body (1) and being used for storing a soil sample solution to be tested; A detection rod (22), wherein the detection rod (22) is vertically arranged at the upper part of the sample tube (21), and the bottom end of the detection rod (22) is provided with a detection end (23) extending into the sample tube (21), a detection cavity (24) is provided inside the detection end (23), and a spectrum detection component is provided inside the detection cavity (24), wherein the spectrum detection component includes a Raman probe (231), an optical mechanism and a base plate (233), the Raman probe (231) is vertically installed at the upper part of the detection cavity (24), the optical mechanism includes a laser emitter (2321) and a laser receiver (2322), the laser emitter (2321) is installed at the bottom end of the Raman probe (231), the laser receiver (2322) is provided outside the Raman probe (231), and the base plate (233) is provided at the bottom of the detection cavity (24) and directly facing the laser emitter (2321); A plurality of through holes (234) communicating with the detection cavity (24) are provided around the middle of the outer peripheral surface of the detection end (23), and a filter (2341) is provided in the through hole (234); A transparent partition (235) is further provided inside the detection cavity (24) and above the through hole (234). The transparent partition (235) is used to divide the detection cavity (24) into a sealed cavity (241) and an excitation cavity (242) from top to bottom. The Raman probe (231) and the optical mechanism are located in the sealed cavity (241). The base plate (233) is located in the excitation cavity (242). The bottom of the excitation cavity (242) is recessed downward to form a hemispherical receiving groove (2421). The receiving groove (2421) transitions to the through hole (234) in an arc shape, and the base plate (233) is parallelly attached to the receiving groove (2421). A bearing sealing ring is provided at a position where the outside of the detection end (23) and the top end of the sample tube (21) penetrate each other. The detection end (23) is rotationally engaged with the sample tube (21) through the bearing sealing ring. The detection end (23) is rotationally connected to the detection rod (22). A stirring member (27) is also provided at a position corresponding to the through hole (234) at the bottom of the detection end (23). A layer of noble metal nanoparticles is also coated on the upper portion of the base plate (233), and nano-spiral grooves are staggered on the surface of the noble metal nanoparticle layer to guide the solution to form a vortex flow when entering the receiving groove (2421) in the excitation cavity.

2. The soil pH detection device based on Raman spectroscopy according to claim 1, characterized in that: A detection and analysis unit is further provided inside the detection body (1), the detection and analysis unit comprising a spectrometer (3) electrically connected to the laser receiver (2322), the spectrometer (3) being connected to an external processing device via a data interface.

3. The soil pH detection device based on Raman spectroscopy according to claim 1, characterized in that: An optical lens group is further provided on the upper portion of the transparent partition (235), the optical lens group comprising a first focusing lens (236) and a second focusing lens (237), the first focusing lens (236) being provided at the transmitting end of the laser transmitter (2321), and the second focusing lens (237) being provided at the receiving end of the laser receiver (2322).

4. The soil pH detection device based on Raman spectroscopy according to claim 1, characterized in that: A mounting plate (6) for mounting a laser receiver (2322) is fixedly mounted on the outside of the Raman probe (231), the bottom surface of the mounting plate (6) being recessed upward and shaped like an inverted bowl, a plurality of laser receivers (2322) are provided, and an array of the plurality of laser receivers (2322) is attached to the bottom surface of the mounting plate (6).

5. The soil pH detection device based on Raman spectroscopy according to claim 1, characterized in that: The top end of the sample cylinder (21) is closed, and a feed pipe (4) and a discharge pipe (5) extending to the outside of the detection body (1) are respectively connected to both sides of the sample cylinder (21).

6. The soil pH detection device based on Raman spectroscopy according to claim 1, characterized in that: A driving device (25) is further provided at the top end of the sample cylinder (21). The output end of the driving device (25) is connected to the detection end (23) via a transmission mechanism (26). The detection end (23) is driven to rotate by the driving device (25).

7. A soil pH detection method based on Raman spectroscopy, characterized in that: According to the soil pH detection device based on Raman spectroscopy according to any one of claims 1 to 6, the method comprises the following steps: Step 1: Mix the soil sample to be tested with a solvent to prepare a soil sample solution, and inject the soil sample solution into the sample cylinder (21) through the feeding tube (4); Step 2, while the soil sample solution is being added, the driving device (25) is started to drive the detection end (23) to rotate, and the detection end (23) drives the stirring member (27) to stir the soil sample solution entering the sample tube (21) to form a uniform dispersion system. At the same time, as the detection end (23) and the stirring member (27) rotate, the soil sample solution is prompted to enter the excitation cavity (242) of the detection cavity (24) through the through hole (234); Step 3, after the soil sample solution enters the excitation cavity (242), the driving device (25) is turned off to stop the rotation of the detection end (23), and the discharge pipe (5) is opened to discharge the remaining soil sample solution in the sample tube (21), and then the laser emitter (2321) is controlled to emit laser light. After the laser light is focused by the first focusing lens (236), it passes through the transparent partition (235) and is emitted to the soil sample solution in the receiving tank (2421) in the excitation cavity (242). The soil particles in the soil sample solution interact with the laser light to generate Raman scattered light. The Raman scattered light passes through the transparent partition (235) and is focused by the second focusing lens (237). It is then received by the laser receiver (2322) located around the Raman probe (231) and transmitted to the spectrometer (3); Step 4: The spectrometer (3) analyzes and processes the received Raman spectrum electrical signal and outputs it to an external processing device. The external processing device calculates the pH value of the soil sample solution based on a pre-established relationship model between the Raman spectrum and the soil pH value.

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