Miniature absorbance method nitrate sensor

Abstract

The utility model discloses a miniature nitrate sensor adopting an absorbance method, and belongs to the field of water quality monitoring. An optical detection assembly in the micro absorbance method nitrate sensor comprises a UVC-LED light source, a light guide quartz column and a photodiode; wherein the center of the UVC-LED light source is opposite to the center of the photodiode through the light guide quartz column; the UVC-LED light source comprises a first light-emitting chip with the wavelength of 235 + / -5 nm and a second light-emitting chip with the wavelength of 275 + / -5 nm. The first light-emitting chip with the wavelength of 235 + / -5 nm and the second light-emitting chip with the wavelength of 275 + / -5 nm are packaged through a ceramic structure which is formed by double-core symmetrical integrated packaging. The photodiode is a silicon-based photodiode packaged by metal; the UVC-LED light sources with the double wavelengths of 235 + / -5nm and 275 + / -5nm are adopted, and miniaturization and high stability of the sensor are achieved through the integrated packaging technology.

Description

Technical Field

[0001] This utility model relates to the field of water quality monitoring technology, and more specifically, to a miniature absorbance nitrate sensor. Background Technology

[0002] Nitrate is a common water pollutant in environmental water bodies, mainly originating from agricultural fertilization, industrial wastewater, and domestic sewage. High concentrations of nitrate can lead to eutrophication, causing algal blooms and red tides, severely impacting the balance of aquatic ecosystems. In wastewater biological treatment, nitrate is a crucial water quality parameter; its concentration changes reflect the nitrogen removal efficiency of nitrification and denitrification processes. Therefore, sensitive and rapid monitoring of nitrate concentration is of great significance for water environment quality control and water treatment process regulation.

[0003] Traditional methods for nitrate detection mainly include chemical colorimetry, ion-selective electrode methods, ion chromatography, and absorption spectroscopy. Absorption spectroscopy utilizes the absorption characteristics of nitrates under ultraviolet light of specific wavelengths, and calculates the concentration by measuring its absorbance. It has high sensitivity and accuracy, and is fast, making it a widely used method.

[0004] In spectroscopic methods, traditional full-spectrum nitrate spectrometers typically use xenon lamps as the light source. However, xenon lamps are bulky, consume a lot of power, and are expensive, making them unsuitable for the design of portable and low-power devices. Furthermore, full-spectrum nitrate spectrometers require complex optical path designs and high-precision dispersive systems, further increasing the size and cost of the equipment. UVC-LED light sources offer advantages such as small size, low energy consumption, long lifespan, and low cost. Moreover, through material selection and structural design, they can achieve narrowband emission at specific wavelengths to meet specific analytical needs. Chinese patents CN215953347U (Dissolved Organic Matter and Nitrate Water Quality Monitoring Probe) and CN214844785U (Dissolved Organic Matter and Nitrate Nitrogen Water Quality Analyzer) disclose detection technologies for nitrate nitrogen and dissolved organic matter based on UVC-LED light sources. Their common feature is the use of independently packaged 235nm and 275nm LED light sources, employing two independent photodiodes and their corresponding operational amplifier circuits to detect the corresponding LED light intensity signals and calculate the absorbance at 235nm and 275nm. The absorbance at 235nm is used to quantify nitrate concentration, while the absorbance at 275nm is used to subtract the interference of organic matter on the nitrate absorbance at 235nm. Absorbance A = A 235 -α×A 275 The coefficient α is the A of organic matter. 235 / A 275However, the 235nm LED and 275nm LED in the scheme disclosed in the application are two independent devices, employing two detection optical paths and their structural designs, and the structure is still too large. Utility Model Content

[0005] 1. Technical problem to be solved by the utility model

[0006] To address the issue of large size in existing absorbance nitrate sensors with multiple detection optical paths, a miniature absorbance nitrate sensor is provided.

[0007] 2. Technical Solution

[0008] To achieve the above objectives, the technical solution provided by this utility model is as follows:

[0009] This invention relates to a miniature absorbance-based nitrate sensor.

[0010] It includes a housing, connectors, circuit boards, and aviation joints connected in sequence;

[0011] The housing includes a front protective housing, an optical detection component, and a rear protective housing connected in sequence.

[0012] The fixed column is provided with a UVC-LED light source, a first light guide quartz column, a second light guide quartz column, and a photodiode in sequence along the axial direction. The first light guide quartz column and the second light guide quartz column are spaced apart, and a notch is opened between the first light guide quartz column and the second light guide quartz column.

[0013] The UVC-LED light source includes a first light-emitting chip with a wavelength of 235±5nm and a second light-emitting chip with a wavelength of 275±5nm;

[0014] The first light-emitting chip with a wavelength of 235±5nm and the second light-emitting chip with a wavelength of 275±5nm are packaged in a dual-core symmetrical integrated ceramic structure.

[0015] The photodiode is a silicon-based photodiode with metal encapsulation.

[0016] Furthermore, the dimensions of the ceramic structure are 3.9×3.9mm, 3.5×3.5mm, or 5.0×5.0mm;

[0017] The photodiode is a silicon-based photodiode with a TO18, TO46, or TO39 metal package.

[0018] Preferably, the ceramic structure has dimensions of 3.9 × 3.9 mm.

[0019] Furthermore, the UVC-LED light source also includes internal pads and electrode pins.

[0020] The internal pads are electrically connected to the electrode pins via conductive posts.

[0021] Furthermore, the first light-emitting chip with a wavelength of 235±5nm is connected in parallel with a Zener diode;

[0022] The second light-emitting chip with a wavelength of 275±5nm is connected in parallel with a Zener diode.

[0023] Furthermore, the UVC-LED light source also includes heat dissipation pins for heat dissipation.

[0024] Furthermore, the optical detection assembly includes a fixed column with a notch;

[0025] The sidewalls on both sides of the notch are respectively provided with a first through hole and a second through hole on the same axis.

[0026] The first through hole contains a first light guide quartz pillar and a photodiode.

[0027] A second light guide quartz pillar and a UVC-LED light source are installed inside the second through hole;

[0028] Furthermore, the first through hole includes a coaxial first light-transmitting hole and a first cavity.

[0029] The diameter of the first light-transmitting hole is smaller than the diameter of the first cavity.

[0030] The first cavity is used to install a photodiode, and the first light-transmitting hole is used to install a first light-guiding quartz pillar;

[0031] The second through hole includes a coaxial second light-transmitting hole and a second cavity.

[0032] The diameter of the second light-transmitting hole is smaller than the diameter of the second cavity.

[0033] The second cavity is used to install a UVC-LED light source, and the second light-transmitting hole is used to install a second light-guiding quartz column.

[0034] Furthermore, the optical detection assembly includes a fixed column with a notch;

[0035] The sidewalls on both sides of the notch are respectively provided with a first through hole and a second through hole on the same axis.

[0036] The first light guide quartz pillar and UVC-LED light source are installed inside the first through hole;

[0037] A second light-guiding quartz pillar and a photodiode are installed inside the second through hole.

[0038] Furthermore, the first through hole includes a coaxial first light-transmitting hole and a first cavity.

[0039] The diameter of the first light-transmitting hole is smaller than the diameter of the first cavity.

[0040] The first cavity is used to install a UVC-LED light source, and the first light-transmitting hole is used to install a first light-guiding quartz column;

[0041] The second through hole includes a coaxial second light-transmitting hole and a second cavity.

[0042] The diameter of the second light-transmitting hole is smaller than the diameter of the second cavity.

[0043] The second cavity is used to install a photodiode, and the second light-transmitting hole is used to install a second light-guiding quartz column.

[0044] Furthermore, the rear protective housing is connected to the connector.

[0045] Furthermore, the circuit board includes a motherboard, an LED circuit board, and a photodiode mounting plate;

[0046] The motherboard is equipped with two LED driver circuits and two photodiode signal operational amplifier circuits.

[0047] The photodiode signal operational amplifier circuit includes a first-stage transimpedance operational amplifier circuit and a second-stage non-inverting amplifier circuit.

[0048] The first-stage transimpedance operational amplifier circuit is used to amplify the light intensity signals of the first and second light-emitting chips of the photodiode.

[0049] Furthermore, the motherboard is also equipped with a microcontroller chip and its auxiliary circuits, a power management circuit, and an RS485 communication circuit.

[0050] Furthermore, the motherboard is fixedly connected to the connector.

[0051] Furthermore, the fixed column is also provided with a wire-passing hole, which is used for the electrical connection between the UVC-LED light source and / or photodiode and the circuit board.

[0052] 3. Beneficial effects

[0053] Compared with the prior art, the technical solution provided by this utility model has the following advantages:

[0054] (1) The UVC-LED light source in the miniature absorbance nitrate sensor provided by this utility model includes a first light-emitting chip with a wavelength of 235±5nm and a second light-emitting chip with a wavelength of 275±5nm. The first light-emitting chip with a wavelength of 235±5nm and the second light-emitting chip with a wavelength of 275±5nm are packaged by a dual-core symmetrical integrated ceramic structure. The photodiode is a metal-packaged silicon-based photodiode. The use of dual-wavelength UVC-LED light sources of 235±5nm and 275±5nm, and the miniaturization and high stability of the sensor are achieved through integrated packaging technology. The use of a single photodiode to detect the light intensity of the dual-wavelength LED light source simplifies the optical path design and reduces the size and cost of the device. Compared with the structure of two detection optical paths in the prior art, the diameter can be reduced by 1 / 2.

[0055] (2) The miniature absorbance nitrate sensor provided by this utility model has two LED driving circuits and two photodiode signal operational amplifier circuits on its circuit board. The photodiode signal operational amplifier circuit includes a first-stage transimpedance operational amplifier circuit and a second-stage non-inverting amplifier circuit. When the second light-emitting chip is working, the microcontroller will collect the amplified signal in the first-stage transimpedance operational amplifier circuit as the light intensity emitted by the second light-emitting chip. When the first light-emitting chip is working, the amplified signal in the first-stage transimpedance operational amplifier circuit is weaker, so the signal in the second-stage non-inverting amplifier circuit is used as the light intensity emitted by the first light-emitting chip. For the signal output of the photodiode, dual operational amplifier circuits with different operational amplifier multiples are designed to collect the light intensity of the LED light source of two wavelengths respectively, thereby improving the sensitivity and accuracy of detection. Attached Figure Description

[0056] Figure 1 This is an overall structural diagram of a miniature absorbance nitrate sensor according to Embodiment 1 of this utility model.

[0057] Figure 2 This is an exploded view of the upper part of a miniature absorbance nitrate sensor according to Embodiment 1 of this utility model.

[0058] Figure 3 This is an exploded view of a miniature absorbance nitrate sensor according to Embodiment 1 of this utility model.

[0059] Figure 4 This is a schematic diagram of the optical detection component in Embodiment 1 of this utility model.

[0060] Figure 5 This is a schematic diagram of the structure of the UVC-LED light source in Embodiment 1 of this utility model.

[0061] Figure 6 This is a schematic diagram of the bottom structure of the UVC-LED light source in Embodiment 1 of this utility model.

[0062] Figure 7 The diagram shows (a) the structural dimensions and (b) the bottom structural dimensions of the UVC-LED light source in Embodiment 1 of this utility model.

[0063] Figure 8 This is a schematic diagram of the first-stage transimpedance operational amplifier circuit and the second-stage non-inverting amplifier circuit in the photodiode signal operational amplifier circuit of Embodiment 1 of this utility model.

[0064] Explanation of the labels in the diagram:

[0065] 100. Aviation connector;

[0066] 200. Circuit board;

[0067] 300. Connectors;

[0068] 400. Housing; 410. Rear protective housing; 420. Optical detection assembly; 421. Photodiode; 422. UVC-LED light source; 4221. First light-emitting chip; 4222. Second light-emitting chip; 4223. Zener diode; 4224. Internal pad; 4225. Conductive post; 4226. Electrode pin; 4227. Heat dissipation pin; 4231. First light guide quartz post; 4232. Second light guide quartz post; 4241. First through hole; 4242. Second through hole; 425. Through hole; 426. Fixing post; 430. Front protective housing. Detailed Implementation

[0069] To further understand the content of this utility model, a detailed description of this utility model will be provided in conjunction with the accompanying drawings and embodiments.

[0070] The structures, proportions, and sizes illustrated in the accompanying drawings are merely for illustrative purposes and to aid those skilled in the art in understanding and reading the invention. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and purpose of the invention, should still fall within the scope of the technical content disclosed in this utility model. Furthermore, terms such as "upper," "lower," "left," "right," and "middle" used in this specification are merely for clarity and not intended to limit the scope of implementation. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention's implementation.

[0071] Example 1

[0072] Combination Figures 1-3This embodiment of a miniature absorbance nitrate sensor includes a housing 400, a connector 300, a circuit board 200, and an aviation connector 100 connected in sequence. The housing 400 includes a front protective housing 430, an optical detection assembly 420, and a rear protective housing 410 connected in sequence. A UVC-LED light source 422, a first light-guiding quartz pillar 4231, a second light-guiding quartz pillar 4232, and a photodiode 421 are sequentially arranged along the axial direction inside the fixed column 426. The first light-guiding quartz pillar 4231 and the second light-guiding quartz pillar... The light guide quartz pillars 4232 and 4232 are spaced apart, with a notch between the first light guide quartz pillar 4231 and the second light guide quartz pillar 4232. The UVC-LED light source 422 includes a first light-emitting chip 4221 with a wavelength of 235±5nm and a second light-emitting chip 4222 with a wavelength of 275±5nm. The first light-emitting chip 4221 with a wavelength of 235±5nm and the second light-emitting chip 4222 with a wavelength of 275±5nm are packaged in a dual-core symmetrical integrated ceramic structure. The photodiode 421 is a metal-packaged silicon-based photodiode. The aviation connector 100 is used for power supply and data transmission. In one specific embodiment, the rear protective housing 410 can be fixedly connected to the connector 300 by a threaded connection, and both ends of the optical detection assembly 420 are fixedly connected to the front protective housing 430 and the rear protective housing 410 by threaded connections, respectively. Employing a dual-wavelength UVC-LED light source 422 (235±5nm and 275±5nm), the sensor achieves miniaturization and high stability through integrated packaging technology. A single photodiode 421 is used to detect the light intensity of the dual-wavelength LED light source, simplifying the optical path design and reducing the size and cost of the device. Furthermore, this sensor is compact, low-power, and low-cost, enabling sensitive, rapid, and accurate detection of nitrates in water.

[0073] As an optional implementation, the ceramic structure has dimensions of 3.9×3.9mm, 3.5×3.5mm, or 5.0×5.0mm, and the photodiode 421 is a silicon-based photodiode 421 with a TO18 metal package. As a preferred implementation, the ceramic structure has dimensions of 3.9×3.9mm. The first light-emitting chip 4221 with a wavelength of 235±5nm and the second light-emitting chip 4222 with a wavelength of 275±5nm can be existing UVC-LED light-emitting chips. For example, both the first light-emitting chip 4221 and the second light-emitting chip 4222 can be purchased from Qingdao Yingguang Innovation Technology Co., Ltd.

[0074] In one specific implementation, the connector 300 can be a cylinder with a cavity, the circuit board 200 is fixedly connected in the cavity of the connector 300, and the rear protective housing 410 and the aviation connector 100 can be threadedly connected to the connector 300.

[0075] Combination Figure 5 , Figure 6 Furthermore, the UVC-LED light source 422 also includes an internal pad 4224 and electrode pins 4226. The internal pad 4224 is electrically connected to the electrode pins 4226 via conductive posts 4225. Specifically, the conductive posts 4225 penetrate the internal pad 4224 on the upper surface of the ceramic structure and the electrode pins 4226 on the bottom surface. The electrode pins 4226 can be connected to the first light-emitting chip 4221 and the second light-emitting chip 4222 on the front side through through-holes, and can be in pairs.

[0076] A first light-emitting chip 4221 with a wavelength of 235±5nm is connected in parallel with a Zener diode 4223, and a second light-emitting chip 4222 with a wavelength of 275±5nm is also connected in parallel with a Zener diode 4223 to protect the light-emitting chips from electrostatic discharge. The UVC-LED light source 422 also includes a heat dissipation pin 4227 for heat dissipation to prevent the light-emitting chips from failing due to overheating. Specifically, the internal pads 4224, electrode pins 4226, the first light-emitting chip 4221, the second light-emitting chip 4222, the heat dissipation pin 4227, and the Zener diode 4223 are disposed on a ceramic structure. Figure 7 In one specific implementation, the ceramic structure has dimensions of 3.9 × 3.9 mm, i.e., W is 3.9 mm and L is 3.9 mm; the width d1 of the electrode pins 4226 is 0.53 mm, and the length d3 of a set of electrode pins 4226 is 3.3 mm; the electrode pins 4226 and the heat dissipation pins 4227 are arranged parallel to each other, and the distance d2 between the electrode pins 4226 and the heat dissipation pins 4227 is 0.45 mm. The UVC-LED light source 422 can achieve independent control of the first light-emitting chip 4221 and the second light-emitting chip 4222.

[0077] Combination Figure 3 , Figure 4In the optical detection assembly 420, a first through hole 4241 and a second through hole 4242 are respectively provided on the side walls of the notch on both sides of the fixed column 42. The first through hole 4241 houses a first light-guiding quartz column 4231 and a photodiode 421; the second through hole 4242 houses a second light-guiding quartz column 4232 and a UVC-LED light source 422. In one specific embodiment, the first through hole 4241 includes a coaxial first light-transmitting hole and a first cavity. The diameter of the first light-transmitting hole is smaller than the diameter of the first cavity. The first cavity is used to install the photodiode 421, and the first light-transmitting hole is used to install the first light-guiding quartz column 4231. The second through hole 4242 includes a coaxial second light-transmitting hole and a second cavity. The diameter of the second light-transmitting hole is smaller than the diameter of the second cavity. The second cavity is used to install the UVC-LED light source 422, and the second light-transmitting hole is used to install the second light-guiding quartz column 4232. In one specific implementation, the first light guide quartz post 4231 and the second light guide quartz post 4232 can be light guide quartz posts of the same size and shape. The two ends of the fixed post 426 are fixedly connected to the front protective housing 430 and the rear protective housing 410 by means of threads.

[0078] Furthermore, the circuit board 200 includes a main board, an LED mounting plate, and a photodiode mounting plate. The main board is equipped with a microcontroller chip and its auxiliary circuits, a power management circuit, an RS485 communication circuit, two LED driver circuits, and two photodiode signal operational amplifier circuits. The main board in the circuit board 200 is fixedly installed within the connector 300. The UVC-LED light source 422 is fixed through the LED mounting plate in the circuit board 200 and fixed in the second cavity of the fixing post 426. It can be connected to the two LED driver circuits on the main board through wires passing through the wire holes 425, thereby realizing independent switching control of the first light-emitting chip 4221 with a wavelength of 235±5nm and the second light-emitting chip 4222 with a wavelength of 275±5nm. The photodiode 421 is fixed through the photodiode mounting plate in the circuit board 200 and fixed in the first cavity of the fixing post 426. It is connected to the photodiode signal operational amplifier circuit on the main board through wires passing through the wire holes 425. As a specific implementation, the LED driver circuit can use a driver chip of model PT4115.

[0079] Because the output light power of the first light-emitting chip 4221 with a wavelength of 235±5nm and the second light-emitting chip 4222 with a wavelength of 275±5nm differs by thousands of times under the same driving current of 20mA, the first-stage transimpedance operational amplifier circuit and the second-stage non-inverting amplifier circuit included in the photodiode signal operational amplifier circuit amplify the light intensity signals emitted by the first light-emitting chip 4221 and the second light-emitting chip 4222. When the second light-emitting chip 4222 is working, the microcontroller will collect the signal amplified by the first-stage transimpedance operational amplifier circuit as the light intensity emitted by the second light-emitting chip 4222. When the first light-emitting chip 4221 is working, the signal amplified by the first-stage transimpedance operational amplifier circuit is weaker, so the signal in the second-stage non-inverting amplifier circuit is used as the light intensity emitted by the first light-emitting chip 4221 to improve the detection sensitivity and accuracy.

[0080] Combination Figure 8 Specifically, the first-stage transimpedance operational amplifier circuit includes operational amplifier U1. The negative input terminal (IN-) of operational amplifier U1 is connected to photodiode 421. The negative terminal (V-) and positive input terminal (IN+) of operational amplifier U1 are grounded. The signal output terminal (OUT) of operational amplifier U1 is connected to photodiode 421 after passing through capacitor C1 and resistor R1 connected in parallel. The positive terminal (V+) of operational amplifier U1 is connected to terminal P1.

[0081] The two-stage inverting amplifier circuit includes operational amplifier U2. The IN- terminal of operational amplifier U2 is grounded through resistor R3. The IN+ terminal of operational amplifier U2 is connected to the OUT terminal of operational amplifier U1. The OUT terminal of operational amplifier U2 is grounded after passing through resistor R2 and capacitor C2 connected in parallel, and then through resistor R3. The V- terminal of operational amplifier U2 is grounded. The V+ terminal of operational amplifier U2 is connected to terminal P2.

[0082] The working principle of the miniature absorbance nitrate sensor in this embodiment is as follows: The UVC-LED light source 422 in the miniature absorbance nitrate sensor includes a first light-emitting chip 4221 with a wavelength of 235±5nm and a second light-emitting chip 4222 with a wavelength of 275±5nm, so as to emit light with wavelengths of 235±5nm and 275±5nm respectively. Using the UVC-LED light source 422, the absorbance of the water sample at 235±5nm and 275±5nm is detected successively. Specifically, the absorbance of the water sample at 235nm and 275nm can be detected, and the interference of organic matter on the absorbance of nitrate at 235±5nm is removed. Since the output light power of the first light-emitting chip 4221 with a wavelength of 235±5nm and the second light-emitting chip 4222 with a wavelength of 275±5nm differs by thousands of times under the same driving current of 20mA, the photodiode signal operational amplifier circuit includes a first-stage transimpedance operational amplifier circuit and a second-stage non-inverting amplifier circuit. When the second light-emitting chip 4222 is working, the microcontroller will collect the signal amplified by the first-stage transimpedance operational amplifier circuit as the light intensity emitted by the second light-emitting chip 4222. When the first light-emitting chip 4221 is working, the signal amplified by the first-stage transimpedance operational amplifier circuit is weaker, so the signal in the second-stage non-inverting amplifier circuit is used as the light intensity emitted by the first light-emitting chip 4221 to improve the sensitivity and accuracy of detection.

[0083] Example 2

[0084] Basically the same as Example 1, except that:

[0085] The optical detection assembly 420 includes a fixed column 426 with a notch; a first through hole 4241 and a second through hole 4242 are respectively provided on the side walls on both sides of the notch. The first through hole 4241 is equipped with a first light guide quartz column 4231 and a UVC-LED light source 422; the second through hole 4242 is equipped with a second light guide quartz column 4232 and a photodiode 421.

[0086] Furthermore, the photodiode 421 is fixed in the second cavity of the fixing post 426 by the photodiode fixing plate, and is connected to the two parallel photodiode signal operational amplifier circuits on the main board by wires passing through the wire hole 425; the UVC-LED light source 422 is fixed in the first cavity of the fixing post 426 by the LED fixing plate, and is connected to the two independent LED driving circuits on the main board by wires.

[0087] The present invention and its embodiments have been described above illustratively. This description is not restrictive, and the figures shown are only one embodiment of the present invention; the actual structure is not limited thereto. Therefore, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the inventive spirit of the present invention, such designs should fall within the protection scope of the present invention.

Claims

1. A miniature absorbance nitrate sensor, characterized in that: It includes a housing (400), a connector (300), a circuit board (200), and an aviation connector (100) connected in sequence. The housing includes a front protective housing (430), an optical detection component (420), and a rear protective housing (410) connected in sequence. The optical detection component (420) includes a fixed column (426). A UVC-LED light source (422), a first light guide quartz column (4231), a second light guide quartz column (4232), and a photodiode (421) are sequentially arranged in the fixed column (426) along the axial direction. The first light guide quartz column (4231) and the second light guide quartz column (4232) are spaced apart, and a notch is opened between the first light guide quartz column (4231) and the second light guide quartz column (4232). The UVC-LED light source (422) includes a first light-emitting chip (4221) with a wavelength of 235±5 nm and a second light-emitting chip (4222) with a wavelength of 275±5 nm. The first light-emitting chip (4221) with a wavelength of 235±5 nm and the second light-emitting chip (4222) with a wavelength of 275±5 nm are packaged in a dual-core symmetrical integrated ceramic structure; The photodiode (421) is a metal-encapsulated silicon-based photodiode (421).

2. The miniature absorbance nitrate sensor according to claim 1, characterized in that: The UVC-LED light source (422) also includes internal pads (4224) and electrode pins (4226). The internal pad (4224) is electrically connected to the electrode pin (4226) via a conductive post (4225); The first light-emitting chip (4221) with a wavelength of 235±5 nm is connected in parallel with a Zener diode (4223). The second light-emitting chip (4222) with a wavelength of 275±5 nm is connected in parallel with a Zener diode (4223).

3. The miniature absorbance nitrate sensor according to any one of claims 1 to 2, characterized in that: The fixed column (426) has a first through hole (4241) and a second through hole (4242) on the side walls on both sides of the notch.

4. The miniature absorbance nitrate sensor according to claim 3, characterized in that: A first light-guiding quartz pillar (4231) and a photodiode (421) are installed inside the first through hole (4241); The second through hole (4242) is equipped with a second light guide quartz column (4232) and a UVC-LED light source (422). or, The first through hole (4241) is equipped with a first light guide quartz pillar (4231) and a UVC-LED light source (422). The second through hole (4242) contains a second light guide quartz pillar (4232) and a photodiode (421).

5. The miniature absorbance nitrate sensor according to claim 4, characterized in that: The first through hole (4241) includes a coaxial first light-transmitting hole and a first cavity, wherein the diameter of the first light-transmitting hole is smaller than the diameter of the first cavity; The second through hole (4242) includes a coaxial second light-transmitting hole and a second cavity, wherein the diameter of the second light-transmitting hole is smaller than the diameter of the second cavity.

6. The miniature absorbance nitrate sensor according to claim 5, characterized in that: The first cavity is used to install a photodiode (421), and the first light-transmitting hole is used to install a first light-guiding quartz pillar (4231). or, The first cavity is used to install a UVC-LED light source (422), and the first light-transmitting hole is used to install a first light-guiding quartz column (4231).

7. The miniature absorbance nitrate sensor according to claim 6, characterized in that: The second cavity is used to install a UVC-LED light source (422), and the second light-transmitting hole is used to install a second light-guiding quartz column (4232). or, The second cavity is used to install a photodiode (421), and the second light-transmitting hole is used to install a second light-guiding quartz pillar (4232).

8. The miniature absorbance nitrate sensor according to claim 7, characterized in that: The fixed column (426) is also provided with a wire hole (425), which is used for the electrical connection between the UVC-LED light source (422) and / or the photodiode (421) and the circuit board (200).

9. The miniature absorbance nitrate sensor according to claim 8, characterized in that: The circuit board (200) includes a main board; The motherboard is equipped with two LED driver circuits and two photodiode signal operational amplifier circuits. The photodiode signal operational amplifier circuit includes a first-stage transimpedance operational amplifier circuit and a second-stage non-inverting amplifier circuit. The first-stage transimpedance operational amplifier circuit is used to amplify the light intensity signals of the first light-emitting chip (4221) and the second light-emitting chip (4222) of the photodiode (421).

10. The miniature absorbance nitrate sensor according to claim 9, characterized in that: The main board in the circuit board (200) is fixedly connected to the connector (300).

Images