Nitrate sensor based on eight-wavelength led light source

Abstract

The utility model discloses a nitrate sensor based on eight wavelength LED light source, including the casing, the light source chamber, the detection chamber and the control chamber that set up from below to above in proper order in casing, set up the detachable composite package light source board in the light source chamber, set up four visible light LED and four mutual parallel ultraviolet LED on the composite package light source board, set up the flow cell and conductivity measuring electrode in the detection chamber, conductivity measuring electrode has a detection end that stretches into the flow channel of flow cell, on the opposite two sides inner wall of flow cell, set up respectively the first group of light window for visible light detection and the second group of light window for ultraviolet light detection, set up light intensity detection subassembly and control circuit mainboard in the control chamber, and light intensity detection subassembly includes four parallel visible detection photodiode and four parallel ultraviolet detection photodiode, the signal output end electric connection of light intensity detection subassembly is to control circuit mainboard, can realize the real -time detection of nitrate concentration in water quality.

Description

Technical Field

[0001] This utility model relates to the field of nitrate sensors, and more specifically to a nitrate sensor based on an eight-wavelength LED light source. Background Technology

[0002] Nitrate (NO3-) is one of the key pollutants causing eutrophication in water bodies and a core indicator for water quality monitoring. Currently, nitrate detection mainly relies on laboratory methods such as ion chromatography or spectrophotometry. While these methods offer high accuracy, they are cumbersome, time-consuming, and typically take several hours to complete, and involve the consumption of chemical reagents. For example, the current standard GB / T 35496-2017, "General Method for the Determination of Nitrate with Chemical Reagents," is insufficient to meet the demands of modern water environments for high-frequency, real-time online monitoring of sewage outlets, river sections, and groundwater.

[0003] Currently, wavelength detection technology based on ultraviolet absorption spectroscopy has become an effective means of detecting nitrate concentration in water. Its principle is to analyze the absorbance data of water samples in specific ultraviolet bands (such as the characteristic absorption peak of nitrate at 220 nm and reference wavelengths such as 275 nm and 340 nm), and use algorithms to compensate for common interferences such as dissolved organic matter (DOM) and turbidity, thereby achieving the inversion of nitrate concentration.

[0004] However, existing detection equipment for implementing this method has many limitations in its hardware structure, which severely restricts its accuracy and reliability in actual complex water samples. Specifically: 1) Simple optical path structure and insufficient anti-interference capability: Many existing devices use a single optical path or a small number of LEDs, making it difficult to simultaneously acquire high-quality optical signals of a sufficient number of wavelengths. This results in a lack of sufficient data foundation for algorithm compensation, limiting the compensation effect when dealing with water samples from environments with varying compositions, and still heavily relying on cumbersome sample pretreatment. 2) Lack of integrated design and inability to perform coordinated measurements: Nitrate detection is easily affected by various parameters such as water temperature and conductivity. Traditional equipment is mostly a simple stacking of functional modules, lacking an integrated structural design. This prevents efficient synchronous measurement and data fusion of multiple parameters (such as UV absorbance, conductivity, and temperature), limiting the improvement of its final detection accuracy. Utility Model Content

[0005] To address the shortcomings in the hardware structure of existing detection devices mentioned in the background section, this invention provides a nitrate sensor based on an eight-wavelength LED light source that does not require sample pretreatment and offers high detection accuracy.

[0006] This utility model discloses a nitrate sensor based on an eight-wavelength LED light source. The housing is provided with a light source cavity, a detection cavity and a control cavity arranged sequentially from bottom to top. A detachable composite packaged light source board is provided in the light source cavity. The composite packaged light source board is provided with four visible light LEDs and four ultraviolet LEDs connected in parallel to form a composite packaged light source. The detection chamber is equipped with a flow cell and a conductivity measuring electrode. The flow cell is connected to the outside and is used to hold the water sample of the environment to be tested. The conductivity measuring electrode has a probe end that extends into the flow channel of the flow cell. On the inner walls of opposite sides of the flow cell, a first set of light windows for visible light detection and a second set of light windows for ultraviolet light detection are respectively provided; wherein, the first optical axis formed by passing through the first set of light windows and the second optical axis formed by passing through the second set of light windows are both perpendicular to the flow direction of the fluid in the flow cell; The control cavity is equipped with a light intensity detection component and a control circuit main board. The light intensity detection component includes... Four visible detection photodiodes and four ultraviolet detection photodiodes are connected in parallel; the photosensitive surface of the visible detection photodiodes faces the first set of light windows, and the photosensitive surface of the ultraviolet detection photodiodes faces the second set of light windows, for receiving light beams passing through the flow cell; the signal output terminal of the light intensity detection component is electrically connected to the main board of the control circuit; the signal output terminal of the conductivity measurement electrode is electrically connected to the main board of the control circuit.

[0007] Furthermore, the housing is composed of a first module, a second module, and a third module that are detachably connected in sequence along the axial direction. The first module forms the light source cavity, the second module forms the detection cavity, and the third module forms the control cavity. A threaded connection structure is provided between the ends of the adjacent modules.

[0008] Furthermore, the first set of light windows includes a visible light incident window disposed near the light source cavity and a visible light receiving window coaxially opposite to it; the second set of light windows includes an ultraviolet light incident window disposed near the light source cavity and an ultraviolet light receiving window coaxially opposite to it.

[0009] Furthermore, it also includes an electrode mounting window for the probe end of the conductivity measurement electrode to pass through and extend into the flow channel of the flow cell; the electrode mounting window is located on the same plane as the visible light incident window and the ultraviolet light incident window, forming a first three-window structure; or it is located on the same plane as the visible light receiving window and the ultraviolet light receiving window, forming a second three-window structure.

[0010] Furthermore, the conductivity measuring electrode adopts a four-electrode structure, and the electrode material is 316 stainless steel or titanium alloy.

[0011] Furthermore, a base is provided inside the light source cavity, and the composite packaged light source board is detachably fixed to the upper surface of the base.

[0012] Furthermore, a communication interface is provided at the top of the housing, which is electrically connected to the main board of the control circuit. The communication interface is a two-in-one interface for power transmission and data communication.

[0013] Furthermore, the composite packaged light source includes ultraviolet LEDs with center wavelengths of 235±5 nm, 255±5 nm, 275±5 nm, and 340±5 nm, and visible light LEDs with center wavelengths of 450±5 nm, 520±5 nm, 660±5 nm, and 760±5 nm, respectively.

[0014] Furthermore, the three ultraviolet LEDs with center wavelengths of 255±5 nm, 275±5 nm, and 340±5 nm are arranged around the ultraviolet LED with a center wavelength of 235 nm±5 nm.

[0015] Furthermore, the light source emission window and the light signal receiving window are sealed to the side wall of the flow cell.

[0016] Furthermore, it also includes a temperature sensing element, which is disposed inside the light source cavity and electrically connected to the main board of the control circuit.

[0017] Furthermore, it also includes a pressure sensing element, which is disposed below the composite packaged light source inside the light source cavity and is electrically connected to the main board of the control circuit.

[0018] Furthermore, it also includes a cleaning brush assembly and a drive motor that are interconnected. The movable part of the cleaning brush assembly is reciprocated at the light incident window and light receiving window of the flow pool, and the drive motor is electrically connected to the main board of the control circuit.

[0019] Compared with the prior art, this utility model achieves the following effects: 1. By setting up four ultraviolet LEDs and visible LEDs of different wavelengths, a complete optical correction foundation is constructed. This structure can simultaneously acquire two independent physical signals: ultraviolet absorption and near-infrared scattering. Thus, by correcting the two interference sources using existing methods, direct and accurate measurement of nitrate concentration in water samples in complex environments is achieved, completely eliminating the dependence on cumbersome and time-consuming sample pretreatment.

[0020] 2. Determine the conductivity and nitrate concentration in the water sample by adding conductivity measuring electrodes. The relationship between the two factors helps to initially assess the confidence level of the nitrate concentration test results.

[0021] 3. The sensor has a simple and lightweight structure; it only needs to be placed in the water sample to be tested. The current continuous monitoring of nitrate concentration eliminates the need for sampling and returning to the laboratory for testing, greatly improving the convenience of testing.

[0022] 4. By integrating temperature, pressure and other sensing units into the nitrate sensor, the environment of the water sample to be tested can be effectively monitored, ensuring the safety of the nitrate sensor in use; at the same time, it achieves a compact and integrated structure, which facilitates mass production and unified calibration, improving product consistency and quality. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall structure of the nitrate sensor; Figure 2 This is a schematic diagram of the planar structure of a nitrate sensor; Figure 3 This is a schematic diagram of the internal structure of a nitrate sensor; Figure 4 A front view of a tetracrystalline composite packaged ultraviolet LED chip; Figure 5 A front view of a four-crystal composite packaged visible light LED chip; Reference numerals: 1. Light source cavity; 2. Detection cavity; 3. Control cavity; 4. Communication interface; 101. Base; 102. Composite packaged light source board; 103. Visible light LED; 104. Ultraviolet LED; 105. Temperature sensor; 201. Flow cell; 202. Conductivity measuring electrode; 203. Visible light incident window; 204. Ultraviolet light incident window; 205. Visible light receiving window; 206. Ultraviolet light receiving window; 207. Electrode mounting window; 208. Cleaning brush assembly; 301. Light intensity detection assembly; 302. Visible detection photodiode; 303. Ultraviolet detection photodiode; 304. Control circuit main board. Detailed Implementation

[0024] like Figure 1 , Figure 2 , Figure 3 As shown, this utility model discloses a nitrate sensor based on an eight-wavelength LED light source, including a housing, wherein a light source cavity 1, a detection cavity 2 and a control cavity 3 are arranged sequentially from bottom to top inside the housing; The light source cavity 1 includes a base 101 and a composite packaged light source plate 102. The composite packaged light source plate 102 is fixed to the upper surface of the base 101 by nuts. Four visible light LEDs 103 and four ultraviolet LEDs 104 connected in parallel are arranged on the composite packaged light source plate 102 to form a composite packaged light source. In addition to using a fixed composite packaged light source board with a detachable base, this utility model can also be achieved through snap-fit ​​connection structure, guide rail slide structure, plug-in structure or magnetic attraction structure, etc. The purpose is to achieve a quick and reliable detachable connection between the composite packaged light source board and the side wall of the light source cavity, either directly or indirectly through the base, connectors, etc., to the light source cavity, so as to ensure the stability during the operation of the light source. The detection chamber 2 is equipped with a flow cell 201 and a conductivity measuring electrode 202. The flow cell 201 is connected to the outside and is used to hold the water sample of the environment to be tested. The probe end of the conductivity measuring electrode 202 extends into the flow channel of the flow cell 201. The flow cell 201 is provided with a visible light incident window 203 and an ultraviolet light incident window 204 on one side near the light source cavity 1, and a visible light receiving window 205 and an ultraviolet light receiving window 206 that are coaxially opposite to the visible light incident window 203 and the ultraviolet light incident window 204, respectively, on the other side. A fixed bracket is provided on one inner wall of the control cavity 3. A light intensity detection component 301 and a control circuit main board 304 are movably connected to the fixed bracket and electrically connected to each other. The light intensity detection component 301 includes four parallel visible light detection photodiodes 302 and four parallel ultraviolet light detection photodiodes 303. The photosensitive surface of the visible light detection photodiodes 302 faces the visible light receiving window 205, and the photosensitive surface of the ultraviolet light detection photodiodes 303 faces the ultraviolet light receiving window 206, for receiving the light beams emitted by the corresponding visible light LEDs and ultraviolet light LEDs and passing through the flow cell 201. The signal output terminal of the light intensity detection component 301 is electrically connected to the control circuit main board 304. The signal output terminal of the conductivity measuring electrode 202 is also electrically connected to the control circuit main board 304. Furthermore, in this embodiment, the housing is composed of a first module, a second module, and a third module that are detachably connected in sequence along the axial direction. The first module forms the light source cavity 1, the second module forms the detection cavity 2, and the third module forms the control cavity 3. A threaded connection structure is provided between the ends of the adjacent modules, making the housing detachable for easy maintenance and replacement of components such as the light source.

[0025] Furthermore, in this embodiment, an electrode mounting window 207 is provided between the visible light receiving window 205 and the ultraviolet light receiving window 206, forming a three-window structure. The electrode mounting window 207 is provided with an electrode protrusion hole, and the probe end of the conductivity measuring electrode 202 extends into the flow channel of the flow cell through the electrode protrusion hole. By setting the three-window structure and installing it at the middle optical window position, maintaining a symmetrical distribution with the two optical windows on both sides, the representativeness of the conductivity measurement is ensured, and interference with the optical measurement is avoided. Without the need to add additional connecting parts, the conductivity measuring electrode is fixed and the conductivity value of the water sample in the flow cell is detected. The accuracy of the nitrate concentration can be preliminarily identified by the conductivity value in the water sample. In addition, this utility model can also have an electrode mounting window between the visible light incident window and the ultraviolet light incident window to form a three-window structure; an electrode protrusion hole is provided on the electrode mounting window, and the probe end of the conductivity measuring electrode is inserted into the flow channel of the flow cell through the electrode protrusion hole, which can also realize the measurement of the conductivity of the water sample in the fluid cell. Furthermore, in this embodiment, the conductivity measurement electrode adopts a four-electrode structure, and the electrode material is 316 stainless steel, graphite or titanium alloy, with the preferred model being WTW TetraCon 925 graphite four-electrode. Furthermore, in this embodiment, the packaged light source adopts two sets of four-wavelength light sources, specifically including ultraviolet LEDs with center wavelengths of 235 nm, 255 nm, 275 nm, and 340 nm, and visible light LEDs with center wavelengths of 450 nm, 520 nm, 660 nm, and 760 nm. Furthermore, such as Figure 4 As shown, in this embodiment, four ultraviolet LED light sources of different wavelengths are placed on the same motherboard in a counterclockwise direction, with the central 235 nm LED as the reference, and the 255 nm, 275 nm and 340 nm LED light sources all pointing to the same light intensity detection component, to ensure a high degree of consistency of the optical path. The central 235 nm wavelength falls within the nitrate ion absorption band, where the highest sensitivity can be achieved. The uppermost 275 nm wavelength represents the typical absorption peak of dissolved organic matter (such as humic acid and fulvic acid), while nitrate ions show almost no absorption at this point. This structure ensures that the 275 nm optical path nearly overlaps with the 235 nm main optical path, accurately reflecting the contribution of the DOM (Dissolved Organic Matter) to the main measurement signal in the same water sample. Through this vertical structure of "central main measurement, upper correction," not only is the optical path optimized, but more importantly, the hardware layout incorporates multi-level signal processing and verification mechanisms, ultimately enabling rapid in-situ detection of nitrate concentration in water. This effectively solves the key technical challenge of severe interference from dissolved organic matter in traditional methods.

[0026] Furthermore, such as Figure 5In this embodiment, four visible light LEDs of different wavelengths are shown. The LED with a wavelength of 450 nm is located in the center, while the visible light LEDs with wavelengths of 520 nm, 660 nm, and 760 nm are placed counterclockwise on the same motherboard and all point to the same light intensity detection component, ensuring a high degree of consistency in the optical path. This structure effectively overcomes the defect that a single wavelength is easily affected by the particle size and color of particles.

[0027] Furthermore, in this embodiment, the light source emission window, the light signal receiving window, and the flow cell sidewall are sealed together. This sealing and fixing can be achieved by adhesive, laser welding, or by using gaskets / O-rings.

[0028] Furthermore, this embodiment includes a temperature sensing element 105, which is fixedly disposed inside the light source cavity and electrically connected to the main board of the control circuit. It can directly and in real time sense the real temperature of the core working area of ​​the light source, avoiding the delay and error caused by measuring the external temperature. When the temperature exceeds the preset safety threshold, the control circuit can immediately take protective measures. Existing temperature sensors such as thermistor temperature sensor NTC 10K and platinum resistance temperature sensor can be used.

[0029] Furthermore, this embodiment also includes a pressure sensing element, which is disposed below the composite packaged light source inside the light source cavity and electrically connected to the main board of the control circuit. This embodiment uses a non-contact pressure sensing element, such as TE Connectivity MS5839-02BA, which can calculate the liquid level height by measuring the hydrostatic pressure of the liquid and determine whether the nitrate sensor is in an effective working state. This structural design effectively utilizes the vertical space of the light source cavity, avoiding the need for additional sensing cavities or external installation. The sensing element is located below the light source, closer to the water sample being measured, and can directly sense changes in the water sample, reducing measurement delay and path loss.

[0030] Furthermore, this embodiment also includes a cleaning brush assembly 208 and a drive motor connected to each other. The movable part of the cleaning brush assembly is reciprocally disposed at the light incident window and light receiving window of the flow pool. The drive motor is electrically connected to the control circuit motherboard. Furthermore, in this embodiment, a communication interface 4 is provided at the top of the housing. The communication interface is a two-in-one interface for power transmission and data communication, used for external communication and external power supply.

[0031] This utility model, based on an eight-wavelength LED light source, forms two optical paths during the above detection process. Specifically, the light beam emitted by the LED visible light source passes through the visible light incident window, the internal optical path of the pool, and the visible light receiving window, forming a first linear optical path; the light beam emitted by the LED ultraviolet light source passes through the ultraviolet light incident window, the internal optical path of the pool, and the ultraviolet light receiving window, forming a second linear optical path.

[0032] The core purpose of the above-mentioned hardware structure improvement of this utility model is to provide a more stable, reliable and highly integrated physical implementation platform for existing mature nitrate concentration detection algorithms, such as the dissolved organic matter compensation algorithm based on three wavelengths or differential spectroscopy, and the suspended matter compensation algorithm based on near-infrared band scattering signals. Specifically, this structure ensures a high degree of consistency between different optical signal sources in time and space through the coordinated design of "multi-wavelength ultraviolet LED light source array" and "multi-wavelength visible LED light source array". That is, the optical data of all wavelengths originate from the same area of ​​the same water sample to be tested and are collected synchronously or sequentially in a very short time.

[0033] In this utility model, the control circuit motherboard adopts the existing electrical connection between modules, specifically including a PCB board and a microcontroller unit, a light source driving module, a signal conditioning module, a communication interface module, a storage module, and a power management module integrated thereon; the modules are electrically connected through wiring on the PCB board, and the power management module can be integrated on the PCB board to supply power to the power-requiring modules inside the sensor; the light source driving module includes visible light LED driving and ultraviolet LED driving.

[0034] In this utility model, the core control logic of the control circuit motherboard is based on existing optical detection and signal processing technology. The specific algorithm executed itself is not improved. It can adopt any nitrate concentration inversion and interference correction model known to those skilled in the art that is suitable for multi-wavelength absorbance data. The basic workflow is as follows. The collaborative operation of the various functional modules involved in this process falls within the scope of existing technology. Specifically, the microcontroller unit (MCU) generates control signals to drive the visible light LED driver and the ultraviolet LED driver, thereby illuminating ultraviolet and visible light sources of specific wavelengths. The light signal after penetrating the water sample is received and converted into a corresponding weak current or voltage signal. This weak electrical signal is standardized by the signal conditioning module, which typically includes steps such as current-to-voltage conversion, amplification, and filtering to eliminate noise and improve signal quality. Finally, it is converted into a digital signal by the analog-to-digital converter (ADC) for the MCU to read. Based on the received digital signal, the MCU applies Lambert-Beer's law... The absorbance values ​​of the water sample at ultraviolet and visible wavelengths are calculated separately. Using the obtained visible absorbance values, the interference of suspended solids (SS) is quantitatively corrected using existing methods, such as by using a preset scattering model (e.g., a power function model) to estimate and subtract the scattering background interference caused by suspended solids at all other wavelengths. Based on the ultraviolet absorbance values, the absorption contribution of DOM can be effectively subtracted from the total absorbance at the characteristic absorption peak of nitrate (e.g., 220 nm) using the three-wavelength method or differential spectroscopy algorithm known in the art. The nitrate concentration is then obtained by calling the nitrate concentration calibration curve stored in the storage module. The result can be transmitted to the host computer or display unit through a data communication interface module (e.g., UART, I2C).

[0035] This utility model relates to a nitrate sensor that detects water conductivity to identify whether there is a significant error in nitrate concentration. Based on existing technology, the specific principle is as follows: the microcontroller unit reads the measurement value from the conductivity sensor and uses it as an auxiliary reference indicator reflecting the total ion concentration in the water. Since nitrate concentration is one of the contributing factors to water conductivity, under normal circumstances, the two should have a roughly positive correlation. Therefore, when the nitrate concentration value measured by the optical method is abnormally high, while the simultaneously measured conductivity value is low, it can be logically inferred that the optical detection may have produced a significant error due to some interference (such as bubbles, turbidity, etc.). Conversely, when the conductivity value is high, but the nitrate concentration measured by the optical method is abnormally low, it may indicate a specific problem with the optical detection system, such as severe contamination of the optical window, optical component failure, or other issues with the optical detection system, or a special condition in the water quality itself (such as illegal discharge, leakage, etc.). The microcontroller can then trigger an alarm or mark the data as invalid.

[0036] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A nitrate sensor based on an eight-wavelength LED light source, characterized in that, The device includes a housing, within which a light source cavity, a detection cavity, and a control cavity are arranged sequentially from bottom to top; a detachable composite packaged light source board is disposed within the light source cavity; and four visible light LEDs and four ultraviolet LEDs connected in parallel are disposed on the composite packaged light source board to form a composite packaged light source. The detection chamber is equipped with a flow cell and a conductivity measuring electrode. The flow cell is connected to the outside and is used to hold the water sample of the environment to be tested. The conductivity measuring electrode has a probe end that extends into the flow channel of the flow cell. On the inner walls of opposite sides of the flow cell, a first set of light windows for visible light detection and a second set of light windows for ultraviolet light detection are respectively provided; wherein, the first optical axis formed by passing through the first set of light windows and the second optical axis formed by passing through the second set of light windows are both perpendicular to the flow direction of the fluid in the flow cell; The control cavity is equipped with a light intensity detection component and a control circuit main board. The light intensity detection component includes four parallel visible detection photodiodes and four parallel ultraviolet detection photodiodes. The photosensitive surface of the visible detection photodiodes faces the first set of light windows, and the photosensitive surface of the ultraviolet detection photodiodes faces the second set of light windows, for receiving the light beam passing through the flow cell. The signal output terminal of the light intensity detection component is electrically connected to the control circuit main board. The signal output terminal of the conductivity measurement electrode is also electrically connected to the control circuit main board.

2. The nitrate sensor based on an eight-wavelength LED light source according to claim 1, characterized in that, The housing is composed of a first module, a second module, and a third module that are detachably connected in sequence along the axial direction. The light source cavity is formed inside the first module, the detection cavity is formed inside the second module, and the control cavity is formed inside the third module.

3. The nitrate sensor based on an eight-wavelength LED light source according to claim 1 or 2, characterized in that, The first set of light windows includes a visible light incident window disposed near the light source cavity and a visible light receiving window coaxially opposite it; the second set of light windows includes an ultraviolet light incident window disposed near the light source cavity and an ultraviolet light receiving window coaxially opposite it.

4. The nitrate sensor based on an eight-wavelength LED light source according to claim 3, characterized in that, It also includes an electrode mounting window for the probe end of the conductivity measurement electrode to pass through and extend into the flow channel of the flow cell; the electrode mounting window is located on the same plane as the visible light incident window and the ultraviolet light incident window, forming a first three-window structure; or it is located on the same plane as the visible light receiving window and the ultraviolet light receiving window, forming a second three-window structure.

5. The nitrate sensor based on an eight-wavelength LED light source according to claim 1, characterized in that, The composite packaged light source includes ultraviolet LEDs with center wavelengths of 235±5 nm, 255±5 nm, 275±5 nm, and 340±5 nm, and visible light LEDs with center wavelengths of 450±5 nm, 520±5 nm, 660±5 nm, and 760±5 nm, respectively.

6. The nitrate sensor based on an eight-wavelength LED light source according to claim 5, characterized in that, The three ultraviolet LEDs with center wavelengths of 255±5 nm, 275±5 nm, and 340±5 nm are arranged around an ultraviolet LED with a center wavelength of 235 nm±5 nm.

7. The nitrate sensor based on an eight-wavelength LED light source according to claim 1, characterized in that, The top of the housing is provided with a communication interface, which is electrically connected to the main board of the control circuit. The communication interface is a two-in-one interface for power transmission and data communication.

8. The nitrate sensor based on an eight-wavelength LED light source according to claim 1, characterized in that, It also includes a temperature sensing element, which is disposed inside the light source cavity and electrically connected to the main board of the control circuit.

9. The nitrate sensor based on an eight-wavelength LED light source according to claim 1, characterized in that, It also includes a pressure sensing element, which is disposed below the composite packaged light source inside the light source cavity and is electrically connected to the main board of the control circuit.

10. The nitrate sensor based on an eight-wavelength LED light source according to claim 1, characterized in that, It also includes a cleaning brush assembly and a drive motor that are connected to each other. The movable part of the cleaning brush assembly is reciprocally disposed at the light incident window and light receiving window of the flow pool. The drive motor is electrically connected to the main board of the control circuit.

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