Apparatus and system for measuring substances in liquid under test by means of plasma spectroscopy

Abstract

The present disclosure provides an apparatus and system for measuring substances in a liquid under test by means of plasma spectroscopy. The apparatus comprises: an electrode, at least a part of which is adapted to be arranged in a liquid under test and is adapted to be in contact with said liquid, the electrode being adapted to generate plasma in said liquid by means of an applied voltage, wherein the plasma is located in bubbles generated by the applied voltage; and an optical detection element, which is adapted to detect an emission spectrum generated by the plasma in the bubbles, wherein the optical detection element is an optical fiber, and there is no light converging element between the optical detection element and the plasma.

Description

Devices and systems for detecting substances in a liquid using plasma spectroscopy

[0001] Cross-reference of related applications

[0002] This application claims priority to Chinese Patent Application No. 202411416260.7, filed on October 11, 2024, entitled "Apparatus and System for Detecting Substances in a Liquid by Plasma Spectroscopy", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure provides an apparatus, system, and method for detecting substances in a liquid, particularly an apparatus, system, and method for detecting substances in a liquid by means of plasma spectroscopy. Background Technology

[0004] Water quality testing is applied to monitor the water quality of various bodies of water, such as natural water bodies, domestic water, industrial water, wastewater discharge, and water quality in industrial processes. It is used in various occasions and fields for environmental monitoring, health monitoring, industrial safety monitoring, and production process monitoring to detect the water quality of different bodies of water and, based on this, to determine the relevant environmental safety status, production process status, or to monitor whether the wastewater discharge of factories meets environmental standards. Common water quality testing targets include the types and concentrations of heavy metals.

[0005] To effectively meet the continuous monitoring needs of various fields, taking industrial fields as an example, online real-time heavy metal detection is crucial for industrial applications. However, existing online continuous heavy metal detection technologies for industrial use are not only expensive, but also often only detect a single metal per device, have poor tolerance to interference from other substances, and may even generate other toxic waste liquids during the detection process, thus making them unsuitable for industrial use. In addition, devices that are too bulky, require complex operation, or are too expensive are also not convenient to carry to various fields for monitoring substances in aqueous solutions.

[0006] For example, experimental methods for detecting heavy metals, such as inductively coupled plasma optical emission spectrometry (ICP-OES) and flame atomic absorption spectrometry (FAAS), can detect multiple heavy metals and have low detection limits. However, due to the high cost of the instruments, cumbersome sample pretreatment procedures, and lengthy operator training time, they cannot obtain detection results effectively and quickly. In addition, commercially available portable heavy metal detection methods, such as chromogenic reaction and anodic stripping voltammetry, are portable, rapid, and easy to operate. However, they are prone to interactions between metals, which can affect their detection signals.

[0007] Therefore, existing methods or devices for detecting substances in aqueous solutions cannot simultaneously meet important requirements such as portability, small device size, ease of operation, low cost, simultaneous detection of multiple heavy metals, rapid detection, and minimal interference between different metals. Summary of the Invention

[0008] To address the aforementioned challenges in simultaneously achieving efficiency, speed, and accuracy in the detection of substances in aqueous solutions, one approach is to employ aqueous plasma. This involves generating plasma in an aqueous solution using electrodes, detecting the emission spectrum of the plasma optically, and then analyzing the emission spectrum to determine the substances contained in the aqueous solution.

[0009] However, existing aqueous plasma methods suffer from difficulties in effectively collecting the light signals emitted by the plasma. For example, the emission spectrum signal generated by the plasma is easily interfered with by bubbles generated with the plasma, significantly reducing the intensity and accuracy of the collected emission spectrum. The varying bubble sizes, bubble movement and changes, bubble formation and destruction, and optical phenomena such as reflection and refraction caused by the gas-liquid interface all significantly affect the signal intensity and accuracy of the collected plasma emission spectrum. Furthermore, the light signal emitted by the plasma is also easily affected by the properties of the aqueous solution itself, significantly reducing the intensity and accuracy of the collected plasma emission spectrum.

[0010] Therefore, the purpose of this disclosure is to provide a detection device, system, and method that combines the advantages of convenient portability, small device size, simple operation, low cost, simultaneous detection of multiple heavy metals, rapid detection, and minimal interference between different metals. Compared with existing aqueous plasma methods, it is less affected by the characteristics of bubbles or aqueous solutions, and can significantly improve the intensity and accuracy of plasma emission spectra, thereby enabling rapid, effective, and accurate detection of substances in aqueous solutions.

[0011] In view of this, the present disclosure provides an apparatus, system and method for detecting substances in a liquid by plasma spectroscopy, so as to significantly improve the intensity and accuracy of plasma emission spectra in aqueous plasma methods.

[0012] One embodiment of this disclosure provides an apparatus for detecting substances in a liquid by plasma spectroscopy, comprising: an electrode, at least a portion of which is adapted to be disposed in the liquid and adapted to be in contact with the liquid, the electrode being adapted to generate plasma in the liquid by an applied voltage, wherein the plasma is located in a bubble generated by the applied voltage; and a photodetector adapted to detect the emission spectrum generated by the plasma in the bubble, wherein the photodetector is an optical fiber and there is no focusing element between the photodetector and the plasma.

[0013] The apparatus for detecting substances in a liquid by plasma spectroscopy as described above, wherein at least a portion of a photodetector is adapted to be disposed in the liquid to be detected, and at least a portion of the photodetector includes a light-receiving end adapted to be located in a bubble to detect the emission spectrum generated by the plasma in the bubble.

[0014] The apparatus for detecting substances in a liquid by plasma spectroscopy as described above, wherein the photodetector is configured at a first angle relative to the normal direction of the contact surface between the electrode and the liquid, wherein the first angle is 0 degrees with the normal direction of the contact surface.

[0015] The apparatus for detecting substances in a liquid by plasma spectroscopy as described above, wherein at least a portion of a photodetector is adapted to be disposed in the liquid to be detected, and at least a portion of the photodetector includes a light-receiving end, the distance between the light-receiving end and the electrode being configured such that the light-receiving end is adapted to be located within the range of the bubble.

[0016] The apparatus for detecting substances in a liquid by plasma spectroscopy as described above, wherein at least a portion of the photodetector includes a light-receiving end, and the distance between the light-receiving end and the electrode is between 0.1 mm and 4 mm.

[0017] The apparatus for detecting substances in a liquid by plasma spectroscopy as described above, wherein the photodetector is configured at a second angle relative to the normal direction of the contact surface of the electrode in contact with the liquid, wherein the second angle is 90 degrees from the normal direction of the contact surface.

[0018] The apparatus for detecting substances in a liquid by plasma spectroscopy as described above, wherein at least a portion of a photodetector is adapted to be disposed in the liquid to be detected, and at least a portion of the photodetector includes a light-receiving end, the distance between the light-receiving end and the electrode being configured such that the light-receiving end is adapted to be located within the range of the bubble.

[0019] The apparatus for detecting substances in a liquid by plasma spectroscopy as described above, wherein at least a portion of the photodetector includes a light-receiving end, the distance between the light-receiving end and the electrode being between 0.05 mm and 3.5 mm.

[0020] As described above, in the device for detecting substances in a liquid by plasma spectroscopy, the photodetector is configured at a third angle relative to the normal direction of the contact surface between the electrode and the liquid, wherein the angle between the third angle and the normal direction of the contact surface is between a first angle and a second angle, wherein the angle between the first angle and the normal direction of the contact surface is 0 degrees, and the angle between the second angle and the normal direction of the contact surface is 90 degrees.

[0021] The apparatus for detecting substances in a liquid by plasma spectroscopy as described above, wherein at least a portion of a photodetector is adapted to be disposed in the liquid to be detected, and at least a portion of the photodetector includes a light-receiving end, the distance between the light-receiving end and the electrode being configured such that the light-receiving end is adapted to be located within the range of the bubble.

[0022] The apparatus for detecting substances in a liquid by plasma spectroscopy as described above, wherein at least a portion of the photodetector includes a light-receiving end, the distance between the light-receiving end and the electrode being between 0.05 mm and 3.5 mm.

[0023] The apparatus for detecting substances in a liquid by plasma spectroscopy as described above, wherein at least a portion of the photodetector is adapted to be disposed in the liquid to be detected, and at least a portion of the photodetector includes a light-receiving end, the distance between the light-receiving end and the electrode being between 0.05 mm and 10 mm.

[0024] One embodiment of this disclosure provides a system for detecting substances in a liquid by plasma spectroscopy, comprising: an apparatus for detecting substances in a liquid by plasma spectroscopy as described above; a sample chamber configured to hold electrodes and a photodetector and adapted to receive the liquid to be detected; a spectrometer coupled to the photodetector, configured to analyze the emission spectrum generated by the plasma in the bubble detected by the photodetector; and a power supply coupled to the electrodes, configured to provide an applied voltage to the electrodes.

[0025] The system for detecting substances in a liquid as described above via plasma spectroscopy also includes an electronic device electrically connected to the spectrometer, configured to analyze the emission spectrum via the spectrometer.

[0026] As described above, the system for detecting substances in a liquid by plasma spectroscopy includes an electronic device configured to be signal-connected to an external device to provide real-time analytical results of the emission spectrum associated with the liquid being detected.

[0027] The system for detecting substances in a liquid by plasma spectroscopy as described above also includes an electronic device electrically connected to a power source, configured to set parameters of an applied voltage via the power source to adjust the plasma generated in the liquid.

[0028] The system for detecting substances in a liquid by plasma spectroscopy as described above also includes an electronic device electrically connected to the power supply and the spectrometer. The electronic device is configured to synchronize the power supply and the spectrometer to synchronize the generation of plasma and the reception of emission spectra.

[0029] One embodiment of this disclosure provides a method for detecting substances in a liquid by plasma spectroscopy, comprising: providing an electrode in the liquid; contacting the electrode with the liquid; applying an external voltage to the liquid to generate plasma; and detecting the emission spectrum generated by the plasma using a photodetector, wherein the plasma is located in a bubble generated by the external voltage, wherein the photodetector is an optical fiber and there is no focusing element between the photodetector and the plasma.

[0030] The method for detecting substances in a liquid to be tested by plasma spectroscopy as described above, wherein the operation of detecting the emission spectrum generated by the plasma by a photodetector further includes: placing at least a portion of the photodetector in the liquid to be tested, and placing the light-receiving end of at least a portion of the photodetector in a bubble, so as to directly detect the emission spectrum generated by the plasma in the bubble.

[0031] The apparatus, system, and method for detecting substances in a liquid using plasma spectroscopy disclosed herein, by employing an optical fiber without a focusing element as the photodetector, effectively eliminates and removes signal attenuation and interference in the plasma emission spectrum caused by optical phenomena such as varying bubble sizes, bubble movement and changes, bubble generation and destruction, and reflection and refraction at the gas-liquid interface when focusing and coupling light signals to the optical fiber using lenses or other optical elements. It also effectively reduces the absorption of light signals by the liquid relative to the light signal. Therefore, it can effectively and completely collect the plasma emission spectrum signal of the liquid under applied voltage, thereby obtaining effective and accurate analytical and detection results for various substances in the liquid. Furthermore, the simple relative arrangement of electrodes and the photodetector allows detection via plasma emission spectrum, while also offering advantages such as portability, small device size, ease of operation, low cost, simultaneous detection of multiple heavy metals, rapid detection, and minimal interference between different metals.

[0032] Overview of the attached figures

[0033] Figure 1A is a schematic diagram of the configuration of a plasma detection device with a solution external lens group for light collection in the prior art;

[0034] Figure 1B is a schematic diagram of the configuration of a plasma detection device with an in-solution lens group for light collection in the prior art;

[0035] Figure 1C is a schematic diagram of the signal trend obtained by a plasma detection device using an in-solution lens group for light collection in the prior art;

[0036] Figure 2A is a schematic diagram of the configuration of a device for detecting substances in a liquid by plasma spectroscopy in an embodiment of this disclosure;

[0037] Figure 2B is a schematic diagram of the configuration of a device for detecting substances in a liquid by plasma spectroscopy in an embodiment of this disclosure;

[0038] Figure 3 is a schematic diagram comparing the signal intensities obtained by using the prior art and the device for detecting substances in the liquid to be detected by plasma spectroscopy in the embodiments of this disclosure.

[0039] Figure 4 is a comparative schematic diagram of the spectral distributions obtained by using the prior art and the apparatus for detecting substances in the liquid to be detected by plasma spectroscopy in the embodiments of this disclosure.

[0040] Figure 5A is a schematic diagram of the configuration of a device for detecting substances in a liquid by plasma spectroscopy in an embodiment of this disclosure;

[0041] Figure 5B is a schematic diagram of the configuration of a device for detecting substances in a liquid by plasma spectroscopy in an embodiment of this disclosure;

[0042] Figure 6A is a schematic diagram comparing the spectral intensities obtained at different distances between the photodetector and the electrode in one embodiment of this disclosure;

[0043] Figure 6B is a schematic diagram comparing the spectral intensities obtained at different distances between the photodetector and the electrode in one embodiment of this disclosure;

[0044] Figure 7A is a schematic diagram of the configuration of the photodetector and the electrode at different angles in one embodiment of the present disclosure;

[0045] Figure 7B is a schematic diagram comparing the spectral intensities obtained at different angles between the photodetector and the electrode in one embodiment of this disclosure;

[0046] Figure 7C is a schematic diagram comparing the spectral intensities obtained at different angles between the photodetector and the electrode in one embodiment of this disclosure;

[0047] Figure 8 is a schematic diagram of the spectral intensities obtained by applying different external voltages to the electrodes in one embodiment of this disclosure;

[0048] Figure 9 is a schematic diagram of the spectral intensities obtained using different electrode sizes in one embodiment of this disclosure;

[0049] Figure 10 is a schematic diagram of the spectral intensities obtained by applying different pulse times to the electrodes in one embodiment of this disclosure;

[0050] Figure 11 is a schematic diagram of the configuration of a system for detecting substances in a liquid by plasma spectroscopy in one embodiment of this disclosure;

[0051] Figure 12 is a schematic diagram of the configuration of a system for detecting substances in a liquid by plasma spectroscopy in one embodiment of this disclosure;

[0052] Figure 13 is a schematic diagram of the configuration of a system for detecting substances in a liquid by plasma spectroscopy in one embodiment of this disclosure;

[0053] Figure 14 is a flowchart of the steps of a method for detecting substances in a liquid by plasma spectroscopy in an embodiment of the present disclosure.

[0054] Figure 15 is a flowchart of the steps of a method for detecting substances in a liquid by plasma spectroscopy in an embodiment of this disclosure.

[0055] Reference numeral 11 Apparatus for detecting substances in a liquid by plasma spectroscopy 12 Apparatus for detecting substances in a liquid by plasma spectroscopy 21 System for detecting substances in a liquid by plasma spectroscopy 22 System for detecting substances in a liquid by plasma spectroscopy 23 System for detecting substances in a liquid by plasma spectroscopy 51 Apparatus for detecting substances in a liquid by plasma spectroscopy 52 Apparatus for detecting substances in a liquid by plasma spectroscopy 100 Sample area 110 Liquid to be detected 120 Plasma 130 Bubble 150 Sample chamber 200 Electrode 210 Conductive part 220 Insulating part 250 Power supply 300 Photodetector 310 Light-collecting area 320 Light-collecting end 350 Spectrometer 400 Electronic device 80 Existing plasma detection device with external lens group for light collection 801 Liquid to be detected 802 Plasma 803 Bubble 820 Electrode 830 Photodetector 831 Concentrating element 832 Light-collecting area 90 The existing plasma detection device with an in-solution lens assembly for light collection consists of: 901 (liquid to be detected), 902 (plasma), 903 (bubble), 920 (electrode), 930 (photodetector), 931 (focusing element), 932 (light-collecting area), A1 (first angle), A2 (second angle), A3 (third angles I, II, III).IV. Operations in areas S1410~S1440 and S1441~S1443.

[0056] Preferred embodiments of this disclosure

[0057] To illustrate the technical content of this disclosure in detail, the following description, in conjunction with embodiments and accompanying drawings, provides further explanation. It should be noted that, throughout this document, terms such as "first," "second," and "third" are used to distinguish between elements, rather than to limit the elements themselves or indicate a specific order of elements. Furthermore, throughout this document, unless a specific quantity is specifically indicated, the article "a" refers to one element or more than one element.

[0058] To fully understand the purpose, features and effects of this disclosure, the following specific embodiments, in conjunction with the accompanying drawings, will be used to provide a detailed description of this disclosure.

[0059] Figure 1A is a schematic diagram of the configuration of a plasma detection device using an external lens group in the solution for light collection in the prior art; Figure 1B is a schematic diagram of the configuration of a plasma detection device using an internal lens group in the solution for light collection in the prior art; Figure 1C is a schematic diagram of the signal trend obtained by a plasma detection device using an internal lens group in the solution for light collection in the prior art.

[0060] Please refer to Figures 1A and 1B. In the prior art, existing detection devices that use aqueous plasma method to detect the elemental analysis of substances in aqueous solution can be divided into two types: one is a method in which a lens group is placed outside the aqueous solution to collect light (as shown in Figure 1A), and the other is a method in which an underwater lens group is placed in the aqueous solution to collect light (as shown in Figure 1B).

[0061] In the existing plasma detection device 80 with external lens assembly for light collection shown in Figure 1A, an electrode 820 is immersed in the liquid 801 to be detected, and a photodetector 830 is located outside the liquid 801 to prevent interference and loss of the photodetector 830 by the liquid 801. In order to achieve accurate and effective light collection, a focusing element 831 is set at the light collection point of the photodetector 830 so that the light signal of the emission spectrum of the plasma 802 generated by the electrode 820 can be effectively collected into the photodetector 830. The emission spectrum of the plasma 802 is then analyzed by a spectrometer or similar device connected to the photodetector 830 to determine the substances, such as heavy metals, present in the liquid 801 to be detected.

[0062] However, before or simultaneously with the generation of plasma 802, a large number of bubbles 803 are generated around electrode 820 and plasma 802 due to the applied energy. The generation and elimination of these bubbles 803 affect the optical path of the light-collecting region 832 determined by the focusing element 831. In addition to the generation and elimination of bubbles 803, uncertainties such as the different sizes of bubbles 803, the movement of bubbles 803, and the optical properties of reflection and refraction at the gas-liquid interface of bubbles 803 all reduce the signal intensity and accuracy of the emission spectrum generated by plasma 802 collected by the photodetector 830, thus leading to interference and difficulties in subsequent material analysis. It should be noted that, for clarity, multiple bubbles of different sizes and uncertainties are not shown in Figure 1A. In reality, there may be multiple bubbles of different sizes and behaviors in the light-collecting region 832.

[0063] In the existing plasma detection device 90 with an intra-solution lens assembly for light collection shown in Figure 1B, both the photodetector 930 and the electrode 920 are immersed in the liquid to be detected 901 in an attempt to reduce the influence of the bubble 903 on the light collection area 932.

[0064] However, before or simultaneously with the generation of plasma 902, a large number of bubbles 903 will also be generated around the electrode 920 and plasma 902, as well as around the photodetector 930 and its focusing element 931, due to the applied energy. The generation and elimination of these bubbles 903 will also affect the optical path of the light-receiving area 932 defined by the focusing element 931. In addition, besides the aforementioned problems, the generated bubbles 903 may also adhere to the surface of the focusing element 931, further affecting the light-receiving efficiency and its accuracy.

[0065] Please refer to Figure 1C. The trend of signal intensity versus time for the photodetector in a conventional plasma detection device using an existing solution-based lens array is shown in Figure 1C. Due to the aforementioned factors of abundant bubble generation and interference, as the plasma generation time progresses, a large number of bubbles are generated, affecting the optical path for light collection and causing a significant decrease in signal intensity over time. This significantly impacts the signal intensity and resolution of the collected plasma emission spectrum.

[0066] Figure 2A is a schematic diagram of the configuration of an apparatus for detecting substances in a liquid by plasma spectroscopy in an embodiment of the present disclosure; Figure 2B is a schematic diagram of the configuration of an apparatus for detecting substances in a liquid by plasma spectroscopy in an embodiment of the present disclosure.

[0067] Please refer to Figure 2A. To address the issues of signal strength reduction and resolution degradation caused by bubbles, one embodiment of this disclosure provides a device 11 for detecting substances in a liquid using plasma spectroscopy. This device includes a sample region 100, an electrode 200, and a photodetector 300. The sample region 100 is adapted to contain the liquid 110 to be detected.

[0068] At least a portion of electrode 200 is disposed in sample region 100 and adapted to contact the liquid to be tested 110. Electrode 200 is adapted to generate plasma 120 in the liquid to be tested 110 by an applied voltage, wherein plasma 120 is located in bubbles 130 generated by the applied voltage. In one embodiment, electrode 200 extends externally and is partially immersed in the liquid to be tested 110, and generates plasma 120 and bubbles 130 in the defined sample region 100 by an applied voltage. In one embodiment, electrode 200 may be subdivided into a conductive portion 210 that is actually conductive and an insulating portion 220 that provides an insulating cover. At one end of electrode 200 (i.e., the portion in contact with the liquid to be tested 110 in sample region 100), it is, for example, a flat plane, a concave surface, a convex surface, but not limited thereto. That is, a portion of conductive portion 210 is exposed to the liquid to be tested 110, and the remaining portion is covered by insulating portion 220. In one embodiment, the conductive portion 210 and the insulating portion 220 of the electrode 200 may be, for example, a coaxial cylindrical structure. The conductive portion 210 is, for example, encased in the insulating portion 220 in a coaxial cylindrical manner. That is, the conductive portion 210 is a circular surface with a smaller radius in the sample region 100, while the remaining peripheral portion is a circular surface with a larger radius in the sample region 100 of the insulating portion 220. This defines an effective electrode region that can contact the test liquid 110 in the sample region 100 and generate plasma 120 in the test liquid 110. However, the above is only an example. The conductive portion 210 and the insulating portion 220 of the electrode 200 can actually be any combination of shapes, and may not need to be coaxial, with only the insulating portion 220 partially encasing the conductive portion 210. In addition, depending on how the electrode 200 is immersed in the test liquid 110, the electrode 200 may also only have the conductive portion 210 without the additional insulating portion 220. In one embodiment, the conductive portion 210 of electrode 200 is platinum, and the insulating portion 220 of electrode 200 is glass, making electrode 200 a glass-platinum electrode. Furthermore, electrode 200 as described herein refers to the positive electrode, and its negative electrode in one embodiment is made of silver wire, such as Silver wire (CAS: 7440-22-4) manufactured by Alfa Aesar. The negative electrode may be configured to be immersed in the liquid to be tested. In one embodiment, the other end of electrode 200 relative to the liquid to be tested 110 is electrically connected to a power source, such as a power supply, pulse generator, etc., supplying power of different voltages, intensities, periods, pulse widths, etc., to allow electrode 200 to generate plasma 120.

[0069] The photodetector 300 is adapted to detect the emission spectrum generated by the plasma 120 in the bubble 130. The photodetector 300 is an optical fiber, and there is no focusing element between the photodetector 300 and the plasma 120. That is, there is no focusing element on the optical path from the emission spectrum generated by the plasma 120 to the photodetector 300 to focus the light signal of the emission spectrum into the photodetector 300. In other words, in the embodiments of this disclosure, the optical fiber of the photodetector 300 refers to an optical fiber without a focusing element. Specifically, at the receiving end that receives the emission spectrum generated by the plasma 120, there is no focusing element such as a lens, microlens, or coupling connector. This allows the photodetector 300 to have a larger receiving area 310, without being limited to receiving light signals focused to a single focal point. Therefore, it can better collect the signal of the emission spectrum generated by the plasma 120 and is less susceptible to the influence of the bubble 130. For ease of explanation, the term "optical fiber without a focusing element" will be used later in this document to describe an optical fiber in which the light-receiving end of the photodetector 300 corresponding to the plasma 120 does not have a focusing element. In one embodiment, the other end of the photodetector 300 relative to the plasma 120 in the liquid to be detected is electrically connected to a spectrometer to obtain the emission spectrum information of the plasma 120, such as the distribution of wavelength and signal intensity, and can be further analyzed to obtain information on the elemental composition of the liquid to be detected 110. However, it should be noted that after the emission spectrum signal generated by the plasma 120 has entered the optical fiber of the photodetector 300 (i.e., the spectral signal has been collected by the photodetector 300), appropriate optical elements can be provided to transmit the spectral signal. For example, as mentioned above, after the emission spectrum signal generated by the plasma 120 has entered the optical fiber of the photodetector 300, a focusing element can be provided to effectively transmit the light signal collected in the photodetector 300 to the aforementioned spectrometer. Furthermore, in order to accommodate different usage environments and required sizes, the optical fiber can be a bare optical fiber or an optical fiber with a cladding layer for protection.

[0070] Furthermore, it should be noted that all components and the liquid to be tested 110 in the diagram can be located in a processing tank, in any container or device, or directly in a natural body of water without the need for other containers. Also, for clarity of illustration, external signal connections and fixing methods for elements such as electrode 200 and photodetector 300 are omitted. These can be achieved using any well-known fixing or signal transmission method, such as CNC machining of fixtures or signal transmission via wired or wireless connections.

[0071] Therefore, using the device 11 shown in Figure 2A, which detects substances in a liquid by plasma spectroscopy, the plasma 120 generated by the electrode 200 is detected by directly using an optical fiber without a focusing element as the photodetector 300. Since no focusing element such as a lens is used, the light-receiving area 310 and its range of the photodetector 300 can be effectively increased. Furthermore, because no focusing element is used, the light-receiving range of the photodetector 300 is not overly focused on the optical focal point. Therefore, when a large number of bubbles 130 are generated, moved, and changed randomly, one or more bubbles 130 will not significantly affect the focal point position, causing the light-receiving range to deviate from the actual position of the plasma 120. This allows for the effective collection of the light signal generated by the plasma 120, significantly improving the signal intensity, signal resolution, and accuracy of detecting the emission spectrum of the plasma 120.

[0072] Please refer to Figure 2B. The device 12 for detecting substances in a liquid by plasma spectroscopy shown in Figure 2B is largely the same as the device 11 for detecting substances in a liquid by plasma spectroscopy shown in Figure 2A, the only difference being the placement of the photodetector 300. In Figure 2A, the photodetector 300 is positioned directly above the electrode 200, that is, above the normal direction of the contact surface between the electrode 200 and the liquid 110 to be detected. Since it is located in the axial direction of the line connecting the electrode 200 and the plasma 120 it generates, it is also referred to as being positioned in the axial direction. In Figure 2B, the photodetector 300 is positioned in the horizontal direction where the plasma 120 is generated by the electrode 200, that is, in the direction perpendicular to the normal direction of the contact surface between the electrode 200 and the liquid 110 to be detected. Since it is located in the radial direction of the line connecting the electrode 200 and the plasma 120 it generates, it is also referred to as being positioned in the radial direction. The difference between positioning the photodetector 300 in the radial direction and positioning it in the axial direction is that, since the bubble 130 generally moves upward, the photodetector 300 located in the axial direction is more susceptible to the influence of the bubble 130 rising and approaching. Therefore, generally speaking, when both the photodetector 300 and the electrode 200 are in the liquid 110 to be detected but are far apart, the photodetector 300 located in the radial direction is less susceptible to the influence of the generated bubble 130 rising. However, when the photodetector 300 and the electrode 200 are close together, the photodetector 300 located in the axial direction is less susceptible to background interference and can have better signal strength and signal stability, which will be discussed later in this article.

[0073] Figure 3 is a comparative schematic diagram of the signal intensity obtained using the prior art (the existing plasma detection device 80 with external solution lens group and the existing plasma detection device 90 with internal solution lens group shown in Figures 1A and 1B) and the device for detecting substances in the liquid to be detected by plasma spectroscopy in the embodiments of this disclosure (11 in Figure 2A is axially arranged, and 12 in Figure 2B is radially arranged); Figure 4 is a comparative schematic diagram of the spectral distribution obtained using the prior art (the existing plasma detection device 80 with external solution lens group and the existing plasma detection device 90 with internal solution lens group shown in Figures 1A and 1B) and the device for detecting substances in the liquid to be detected by plasma spectroscopy in the embodiments of this disclosure (11 in Figure 2A is axially arranged, and 12 in Figure 2B is radially arranged).

[0074] Please refer to Figure 3, which is an experimental comparison diagram of the signal strength and relative standard deviation (RSD) of the prior art lens group (fourth column), underwater lens (third column), and the optical fiber radial (second column) and short-distance optical fiber axial (first column) provided by the embodiments of this disclosure.

[0075] As can be seen from the fourth column of Figure 3, when using an existing lens group placed outside the liquid to be detected as a photodetector, its signal intensity falls between approximately 6000 a.u. and 13000 a.u., and the RSD falls at 12.8%. It can be seen that although the optical element itself is not directly affected by the liquid to be detected, the generation and changes of bubbles, such as the aforementioned differences in bubble size, movement, and optical characteristics of the gas-liquid interface, will cause the signal received by the lens group to change drastically, resulting in poor stability.

[0076] As shown in the third column of Figure 3, when using an existing underwater lens group placed in the liquid to be detected as a photodetector, its signal intensity falls between approximately 550 a.u. and 1500 a.u., with an RSD of 17.1%. This indicates that although the optical element is placed directly underwater to try to reduce the influence of bubbles on the optical path, it also directly faces interference from a large number of bubbles around the underwater lens group, which also affects the optical path of the collected plasma emission. In addition, since the underwater lens group is located underwater, bubbles will adhere to the surface of the underwater lens group over time, further affecting the light collection efficiency and accuracy. As can be seen in the table, as the plasma generation time progresses, the signal intensity of the underwater lens group decreases significantly compared to other comparison groups, which significantly affects the signal intensity and signal resolution of the emission spectrum within the collected plasma.

[0077] As can be seen from the second column of Figure 3, when the optical fiber without a focusing element provided in one embodiment of this disclosure is used as the photodetector and the light is collected in the radial direction, the signal intensity falls between approximately 21,000 a.u. and 27,000 a.u., and the RSD falls at 5.6%. It can be seen that when the optical fiber is used radially without a focusing element for direct light collection, it can effectively collect the light emitted from the plasma. Unlike existing lens groups and underwater lenses that also collect light radially but with poor results, the radial light collection of the optical fiber in this disclosure (as shown in 12 of Figure 2B) can significantly reduce the interference or influence caused by the bubble because the light collection range is not significantly changed by the bubble as it is after the lens focuses. This results in obtaining a high-intensity and high-stability plasma emission spectrum light signal.

[0078] As can be seen from the first column of Figure 3, when the optical fiber without a focusing element provided in one embodiment of this disclosure is used as the photodetector and light is collected in a short-distance axial direction, the signal intensity falls between approximately 38,000 a.u. and 46,000 a.u., and the RSD falls at 2.3%. It can be seen that when using a short-distance optical fiber for axial light collection, the light emitted from the plasma can be collected optimally. This is because when the optical fiber is brought close to the electrode at a short distance, in addition to retaining the advantages of the original optical fiber without a focusing element, which is not affected by the change in focus caused by the bubble, the distance between the light-receiving end and the plasma can be reduced to reduce interference between optical paths. Furthermore, when the light-receiving end of the optical fiber without a focusing element used as the photodetector is sufficiently close to the electrode and the plasma it generates, the light-receiving end of the optical fiber can be directly located inside the bubble containing the plasma, thereby minimizing the influence of the bubble on light collection and significantly improving the intensity and stability of the optical signal of the plasma emission spectrum.

[0079] Figure 4 is a comparative schematic diagram of the spectral distributions obtained from the comparison results shown in Figure 3. As shown in Figure 4, when the spectral distributions of the existing lens group, underwater lens, and the optical fiber radial and short-distance optical fiber axial without a focusing element provided in this disclosure are examined under the same conditions, it can be seen that, regardless of whether the wavelength is less than about 300 nm or greater than about 330 nm, the uniform signal intensity of the optical fiber radial and short-distance optical fiber axial without a focusing element provided in this disclosure is significantly better than that of the existing lens group and underwater lens in all wavelength bands, except for a single peak. This demonstrates the significant advantage of using an optical fiber without a focusing element as a photodetector in the device for detecting substances in the liquid by plasma spectroscopy provided in this disclosure. Furthermore, in one embodiment, taking the presence of zinc (Zn) in the liquid to be detected as an example, compared to the existing lens groups and underwater lens light collection methods, the use of radial optical fibers without focusing elements or short-distance axial optical fibers as light detection devices provided in the embodiments of this disclosure can better detect the signal emitted by zinc contained in the liquid to be detected (as indicated by the arrow) in the spectrum.

[0080] Figure 5A is a schematic diagram of the configuration of an apparatus for detecting substances in a liquid by plasma spectroscopy in an embodiment of the present disclosure; Figure 5B is a schematic diagram of the configuration of an apparatus for detecting substances in a liquid by plasma spectroscopy in an embodiment of the present disclosure.

[0081] Please refer to Figure 5A. The device 51 for detecting substances in a liquid by plasma spectroscopy shown in Figure 5A is largely the same as the device 11 for detecting substances in a liquid by plasma spectroscopy shown in Figure 2A. The main difference is that at least a portion of the photodetector 300 is disposed in the sample region 100, and at least a portion of the photodetector 300 includes a light-receiving end 320, which is adapted to be located in the bubble 130 to detect the emission spectrum generated by the plasma 120 in the bubble 130.

[0082] Therefore, by directly placing one end of the photodetector 300 in the sample region 100 and by directly placing the light-receiving end 320 of the photodetector 300 near the electrode 200 to the position of the plasma 120 generated by the electrode 200, the light-receiving end 320 can be directly located within the bubble 130 containing the plasma 120. This minimizes the influence of the bubble 130 and its interface on the light collection, as well as the influence of the liquid phase (e.g., water) passed through part of the optical path on the absorption of part of the optical spectrum. The photodetector 300 can directly collect the optical signal of the plasma 120 through the light-receiving end 320 located within the bubble 130. Furthermore, since the light-receiving end 320 of the photodetector 300 is sufficiently close to the electrode 200, the photodetector 300 will no longer be subject to any interference or influence from other bubbles. This also minimizes noise contributions or influences from other gas-liquid interfaces on the background, and prevents the absorption of certain wavelengths of the light signal from the plasma 120 by the passing water. This maximizes the complete collection of the light signal from the emission spectrum generated by the plasma 120 and maximizes its optical path and light-receiving stability. Moreover, when the light-receiving end 320 of the photodetector 300 is sufficiently close to the electrode 200, regardless of whether the bubble 130 forms a film on the surface of the light-receiving end 320, it can remain stable throughout the entire light emission process of the plasma 120 without forming new bubbles or interfering with the interaction between the light-receiving end 320 and the plasma 120. In addition, outside the time when the photodetector 300 detects the emission spectrum generated by the plasma 120, such as before and after the plasma 120 is generated, the bubbles 130 will be generated and disappear as the voltage and time applied by the electrode 200 or other disturbances occur. The change in the interface of the bubbles 130 during the process of their generation from small to large and disappearance can also have a cleaning effect on the light receiving end 320 of the adjacent photodetector 300.

[0083] Please refer to Figure 5B. The device 52 for detecting substances in a liquid by plasma spectroscopy shown in Figure 5B is largely the same as the device 12 for detecting substances in a liquid by plasma spectroscopy shown in Figure 2B. The main difference is that at least a portion of the photodetector 300 is disposed in the sample region 100, and at least a portion of the photodetector 300 includes a light-receiving end 320, which is adapted to be located in the bubble 130 to detect the emission spectrum generated by the plasma 120 in the bubble 130.

[0084] Therefore, compared to the device 51 shown in Figure 5A, which uses plasma spectroscopy to detect substances in a liquid, where the photodetector 300 is axially positioned on the front of the electrode 200, the device 52 shown in Figure 5B uses plasma spectroscopy to detect substances in a liquid, where the photodetector 300 is radially positioned on the side of the electrode 200. Since the light-receiving ends 320 of the photodetectors 300 are positioned sufficiently close to the plasma 120 generated by the electrode 200, their light-receiving ends 320 are located within the bubbles 130 where plasma 120 is generated. This allows for effective and maximized collection of the light signal from the emission spectrum of the plasma 120 without interference from other bubbles or optical paths. When the light-receiving end 320 of the photodetector 300 is close enough to the electrode 200 to be located inside the bubble 130, the axially arranged photodetector 300 (51 in Figure 5A) will not be affected by the rising bubble and cause signal interference. This is because when the photodetector 300 is close enough, its space limitation will reduce the space and probability for the bubble 130 to rise and detach, and even if a bubble rises, it will not affect its light-receiving area 310. Furthermore, compared with the embodiment of the axially arranged photodetector 300 (51 in FIG. 5A) and the embodiment of the radially arranged photodetector 300 (52 in FIG. 5B), the axially arranged photodetector 300 is less susceptible to the influence of other background factors, and thus has higher signal strength and stability than the radially arranged photodetector 300. In addition, the axially arranged photodetector 300 can also hold the bubble 130 in place, making it less likely for the bubble 130 to detach or move relative to the radially arranged photodetector 300, thereby also providing higher signal strength and stability.

[0085] Figures 6A and 6B are schematic diagrams comparing the spectral intensities obtained at different distances between the photodetector and the electrode in the embodiments of this disclosure.

[0086] Please refer to Figure 6A. Figure 6A is a schematic diagram comparing the spectral intensity of the light-receiving end 320 of the photodetector 300 and the electrode 200 at distances of 1 mm (solid line) and 4 mm (dotted line), respectively, when the photodetector 300 is arranged in the axial direction (as shown in 51 of Figure 5A), in one embodiment. Figure 6B is a schematic diagram comparing the spectral intensity of the light-receiving end 320 of the photodetector 300 and the electrode 200 at distances of 0.1 mm (solid line) and 4 mm (dotted line), respectively, when the photodetector 300 is arranged in the axial direction (as shown in 51 of Figure 5A), in these embodiments. In these embodiments, the voltage used to generate the plasma 120 is 600V, the effective size of the electrode 200 (i.e., the conductive part 210 in Figure 5A, the same below) is 0.3 mm, the pulse on-time is 10 ms, and the pulse off-time is 10 ms. As can be seen from Figures 6A and 6B, when the photodetector 300 is close to the electrode 200, the axially positioned photodetector 300 is very close to the plasma 120, so that the photodetector 300 will no longer be interfered with by the bubble 130 and the light signal will not be absorbed by the water (or the liquid to be detected 110) passing by. It can be seen that bringing the photodetector 300 close to the electrode 200 has a significant effect.

[0087] Figure 7A is a schematic diagram of the configuration of the photodetector and the electrode at different angles in an embodiment of the present disclosure; Figure 7B is a schematic diagram comparing the spectral intensities obtained at different angles between the photodetector and the electrode in an embodiment of the present disclosure; Figure 7C is a schematic diagram comparing the spectral intensities obtained at different angles between the photodetector and the electrode in an embodiment of the present disclosure.

[0088] Please refer to Figure 7A, which illustrates the configurations of the photodetector 300 relative to the electrode 200 at first angle A1, second angle A2, and third angle A3, respectively. Specifically, the first angle A1 refers to the photodetector 300 being configured at an angle A1 relative to the normal direction of the contact surface between the electrode 200 and the liquid 110 to be detected. The angle between the first angle A1 and the normal direction of the contact surface is 0 degrees. That is, when the photodetector 300 is at the first angle A1, it is located in the axial direction of the electrode 200 relative to the plasma 120, which is the aforementioned axial direction. The second angle A2 refers to the photodetector 300 being configured at an angle A1 relative to the normal direction of the contact surface between the electrode 200 and the liquid 110 to be detected. The photodetector 300 is positioned at a second angle A2, where the angle between the second angle A2 and the normal direction of the contact surface is 90 degrees. This means that when the photodetector 300 is located at the second angle A2, the photodetector 300 is located in the radial direction of the electrode 200 relative to the plasma 120, which is the aforementioned radial direction. The third angle A3 refers to the photodetector 300 being configured at a third angle A3 relative to the normal direction of the contact surface where the electrode 200 contacts the liquid to be detected 110. The angle between the third angle A3 and the normal direction of the contact surface is between the first angle A1 and the second angle A2.

[0089] Please refer to Figure 7A. As shown in Figure 7A, when the photodetector 300 is positioned at different angles, four different light-collecting distance regions for the photodetector 300 can be defined, namely Region I, Region II, Region III, and Region IV. Among them, Region I is defined as the distance closest to both the electrode 200 and the plasma 120. However, when the photodetector 300 is too close to the electrode 200, it may interfere with the generation of the bubble 130 and the plasma 120 due to the excessively close distance, thus potentially hindering the collection of the emission spectrum of the plasma 120. Next, Region II is defined as the optimal distance for the photodetector 300. This means that when the receiving end 320 of the photodetector 300 is close enough to the electrode 200 without affecting the generation of the bubble 130 or plasma 120, it can most effectively collect the light signal of the emission spectrum generated by the plasma 120 directly within the range of the bubble 130, without being interfered with by the generation or changes of other bubbles, nor by the absorption interference of water or the liquid to be detected. This significantly improves the light collection intensity and accuracy, hence it is the optimal light collection distance for the photodetector 300. Subsequently, Region III is the region where the receiving end 320 gradually moves away from the electrode 200 and the plasma 120 it generates. At this time, the receiving end 320 of the photodetector 300 has detached from the bubble 130 containing plasma 120 itself and begins to be affected by some other bubbles or liquids. However, since the optical fiber is used as the photodetector 300, the emission spectrum signal generated by the plasma 120 will not be significantly affected by the change in focus, and can still be effectively collected into the optical fiber. Finally, in region IV, as the light receiving end 320 moves further away, its photodetector 300 is less likely to be attached to by other bubbles, but the increased distance will increase the impact of absorption by water or the liquid to be detected. However, compared to the existing light receiving methods, the use of optical fiber can still maintain a certain degree of effective light receiving, and will not be severely affected by the change of the existing focus.

[0090] In one embodiment, when the photodetector 300 is positioned at a first angle A1, since it is positioned in the axial direction relative to the electrode 200, it is preferably such that at least a portion of the photodetector 300 is disposed in the sample region 100, and at least a portion of the photodetector 300 includes a light-receiving end 320. The distance between the light-receiving end 320 and the electrode 200 is configured such that the light-receiving end 320 is suitable to be located within the range of the bubble 130, i.e., as described in region II above. Therefore, when the photodetector 300 is positioned at the first angle A1, the optimal light-receiving distance for the photodetector 300 in region II is between 0.1 mm and 4 mm, while in region I it is less than 0.1 mm, and in region III it is greater than 4 mm.

[0091] In one embodiment, when the photodetector 300 is positioned at a second angle A2, since it is positioned radially relative to the electrode 200, it is preferably positioned such that at least a portion of the photodetector 300 is disposed within the sample region 100. This at least portion of the photodetector 300 includes a light-receiving end 320, and the distance between the light-receiving end 320 and the electrode 200 is configured such that the light-receiving end 320 is suitable to be located within the range of the bubble 130, as described in region II above. Therefore, when the photodetector 300 is positioned at the second angle A2, since it is not located above the electrode 200 but to the side, the distance at which it can stabilize the bubble 130 is relatively shorter. The optimal light-receiving distance for the photodetector 300 in region II is between 0.05 mm and 3.5 mm, while in region I it is less than 0.05 mm, in region III it is between 3.5 mm and 4.5 mm, and in region IV it is greater than 4.5 mm.

[0092] In one embodiment, when the photodetector 300 is positioned at a third angle A3, since it is located between the axial and radial directions relative to the electrode 200, it is preferably positioned such that at least a portion of the photodetector 300 is disposed in the sample region 100. This at least portion of the photodetector 300 includes a light-receiving end 320, and the distance between the light-receiving end 320 and the electrode 200 is configured such that the light-receiving end 320 is suitable to be located within the range of the bubble 130, as described in region II above. Therefore, when the photodetector 300 is positioned at the third angle A3, since it is located between the top and side of the electrode 200, the distance at which it can stabilize the bubble 130 is close to the radial direction. The optimal light-receiving distance for the photodetector 300 in region II is between 0.05 mm and 3.5 mm, while in region I it is less than 0.05 mm, in region III it is between 3.5 mm and 4.5 mm, and in region IV it is greater than 4.5 mm.

[0093] Next, please refer to Figures 7B and 7C. As can be seen from the comparison diagram of the spectral intensity obtained at different angles in Figures 7B and 7C, under the same conditions, and when the distance between the photodetector 300 and the electrode 200 is in Region II, the results of light collection by the photodetector 300 at different relative angles show no significant difference in the intensity of the spectral distribution and the signal characteristics of each wavelength. The signal intensity and resolution of the characteristic peaks of each wavelength are stable and clear.

[0094] Figure 8 is a schematic diagram of the spectral intensities obtained by applying different external voltages to the electrodes in one embodiment of this disclosure.

[0095] Please refer to Figure 8, which is an experimental schematic diagram showing the spectral intensity distribution obtained with respect to different applied voltages on the electrodes. The upper part of Figure 8 shows the spectral intensity distribution with an applied voltage of 400V; the lower part shows the spectral intensity distribution with an applied voltage of 1200V. In this case, the electrode sizes for the other operating conditions are 0.3mm and 0.8mm, respectively; the pulse durations are 10ms on-time and 1ms off-time, and 0.2ms on-time and 50ms off-time. As can be seen from the results in Figure 8, the plasma emission spectra generated under applied voltages of 400V and 1200V still retain the main characteristics of their respective wavelengths after reception.

[0096] Figure 9 is a schematic diagram of the spectral intensities obtained using different electrode sizes in one embodiment of this disclosure.

[0097] Please refer to Figure 9, which is an experimental schematic diagram showing the spectral intensity distribution obtained with different electrode sizes. The upper part of Figure 9 shows the spectral intensity distribution with an electrode size of 0.3 mm; the lower part shows the spectral intensity distribution with an electrode size of 0.8 mm. In both cases, the voltage for the remaining operating conditions is 650 V; the on-time and off-time of the applied pulse are both 10 ms. As can be seen from the results in Figure 9, with electrode sizes of 0.3 mm and 0.8 mm respectively, the main characteristics of each wavelength in the generated plasma emission spectrum can still be distinguished after reception.

[0098] Figure 10 is a schematic diagram of the spectral intensities obtained by applying different pulse times to the electrodes in one embodiment of this disclosure.

[0099] Please refer to Figure 10. Figure 10 is an experimental schematic diagram showing the spectral intensity distribution obtained with respect to different pulse times when voltages are applied to the electrodes. The upper part of Figure 10 shows the spectral intensity distribution for an on-time of 800 ms and an off-time of 3000 ms; the lower part of Figure 10 shows the spectral intensity distribution for an on-time of 0.5 ms and an off-time of 0.5 ms. In this case, the voltage for all other operating conditions is 540 V; the electrode size is 0.3 mm. As can be seen from the results in Figure 10, the main characteristics of the plasma emission spectra generated at the applied pulse times of 800 ms on-time, 3000 ms off-time, 0.5 ms on-time, and off-time are still discernible after reception.

[0100] In summary, the apparatus for detecting substances in a liquid by plasma spectroscopy provided in one embodiment of this disclosure operates under the following basic conditions: voltage of 300V to 1200V; electrode size of 0.1mm to 1mm; pulse on-time of 0.01ms to 800ms; distance between the photodetector and the electrode of 0.05mm to 10mm; and light-receiving angle of the photodetector relative to the electrode of 0 degrees to 90 degrees. Under these conditions, the plasma emission spectrum generated can still distinguish the main characteristics of its different wavelengths after reception, thus achieving the purpose of detecting substances in the liquid by plasma spectroscopy and the aforementioned effects.

[0101] Figure 11 is a schematic diagram of the configuration of a system for detecting substances in a liquid by plasma spectroscopy in one embodiment of this disclosure.

[0102] Another embodiment of this disclosure provides a system for detecting substances in a liquid by plasma spectroscopy, comprising: an apparatus for detecting substances in a liquid by plasma spectroscopy as described in the foregoing embodiments (e.g., but not limited to 11, 12, 51, 52), a sample chamber 150, a spectrometer 350, and a power supply 250.

[0103] The sample chamber 150 is configured to hold the electrode 200 and the photodetector 300, forming a sample area 100 between the electrode 200 and the photodetector 300, and is adapted to receive the liquid 110 to be tested. In one embodiment, the sample chamber 150 may include a waterproof tank for accommodating the liquid 110 to be tested, and may have inlets, outlets, pipelines, valves, etc., for the liquid 110 to enter. In one embodiment, the sample chamber 150 may also be a simple rigid support for the electrode 200 and the photodetector 300, such as a one-piece molded structure manufactured by CNC, to provide holding and fixing of the electrode 200 and the photodetector 300. In one embodiment, the sample chamber 150 may further have an adjustable support structure, such as a linear or circular slide rail, a locking structure, or a pre-set slot with multiple angles and distances, to adjust the distance and angle of the photodetector 300 relative to the electrode 200. In one embodiment, the sample chamber 150 may not be a container for holding liquid, but rather a structure that provides a fixed electrode 200 and photodetector 300, allowing it to be directly immersed in any body of water for the detection of substances in the liquid, without the need for liquid sampling, transportation, or input into a device or system.

[0104] The spectrometer 350 is configured to be coupled to the photodetector 300 and to analyze the emission spectrum of the plasma 120 detected by the photodetector 300 in the bubble 130, thereby obtaining emission spectrum information of the plasma 120, such as the characteristic distribution of wavelength and signal intensity and peak signals, and thereby analyzing and obtaining information on the elemental composition of the substance in the liquid 110 to be detected. In one embodiment, the photodetector 300 can communicate optically with the spectrometer 350 using any optical method, such as directly connecting to the spectrometer 350 without other optical elements, continuing to transmit the optical signal to the spectrometer 350 via the original optical fiber, or transmitting the optical signal to the spectrometer 350 via other necessary optical elements, such as lenses, beam dividers, etc., so that the spectrometer 350 can receive the complete signal from the photodetector 300. It should be noted that the lines drawn in Figures 11 and 12 and 13 on the photodetector 300, the spectrometer 350 and the connections between them are only schematic and do not represent actual physical or spatial differences or sizes. Furthermore, the dimensions and proportions of the bubble 130, plasma 120, electrode 200, photodetector 300, and other components shown in the accompanying drawings are merely examples for clarity, and the dimensions, spacing, proportions, and angles depicted are for reference only and not as limitations.

[0105] The power supply 250 is configured to be coupled to the electrode 200, particularly to the conductive portion 210 of the electrode 200. The power supply 250 is configured to provide an applied voltage to the electrode 200, enabling the electrode 200 to generate plasma 120 and its bubbles 130 in the liquid 110 to be detected. In one embodiment, the power supply 250 can be a power supply, a function generator, a pulse generator, a high-voltage function generator, etc., capable of supplying electrical energy of different voltages, intensities, periods, pulse widths, etc., to enable the electrode 200 to generate plasma 120. It should be noted that the lines drawn in Figures 11 and 12 and 13 depicting the electrode 200, the power supply 250, and the connections between them are merely schematic and do not represent actual physical or spatial differences in size or distance, nor do they represent actual size proportions.

[0106] Figure 12 is a schematic diagram of the configuration of a system 22 for detecting substances in a liquid by plasma spectroscopy in an embodiment of the present disclosure; Figure 13 is a schematic diagram of the configuration of a system 23 for detecting substances in a liquid by plasma spectroscopy in an embodiment of the present disclosure.

[0107] Please refer to Figures 12 and 13. In one embodiment, the system 22 for detecting substances in a liquid by plasma spectroscopy disclosed herein may further include an electronic device 400, which is configured to be electrically connected to a spectrometer 350 and configured to further analyze information from the emission spectrum generated by the plasma 120 via the spectrometer 350.

[0108] In one embodiment, the electronic device 400 is further configured to be signal-connected to an external device (not shown) to provide the external device with the analysis results of the emission spectrum of the liquid 110 to be tested in real time. In one embodiment, the external device may be further connected to other external electronic devices, such as a user's computer, mobile phone, or a monitoring system of a home, company, factory, or government unit, to provide information on the detection results of the liquid 110 to be tested in real time to the aforementioned monitoring system. When abnormal substances are detected in the liquid, such as heavy metals or other elements that do not comply with environmental regulations, users and monitoring systems can be notified in real time to deal with the relevant water pollution situation. Therefore, the device and system for detecting substances in a liquid by plasma spectroscopy disclosed herein not only provide functions for case-by-case, non-continuous, and non-routine liquid or water quality detection, but also provide functions for fixed-location, long-term real-time or non-real-time liquid and water quality detection, and can be applied in a wide range of occasions and fields.

[0109] In one embodiment, the system 23 for detecting substances in a liquid by plasma spectroscopy may also include an electronic device 400 configured to be electrically connected to a power supply 250, and configured to set the parameters of an applied voltage via the power supply 250 to adjust the characteristics of the plasma 120 generated in the liquid 110, such as adjusting the voltage, intensity, period, and pulse width applied to the electrode 200. In one embodiment, the electronic device 400 is not necessarily an additional device, but may be a simple circuit module, microprocessor, IC circuit, etc., attached to the spectrometer 350 or the power supply 250. Furthermore, through the connection of the electronic device 400, programmable control of the spectrometer 350 and the power supply 250 can be achieved separately, or programmable control of the spectrometer 350 and the power supply 250 can be achieved together, and remote programmable control can be achieved, thereby realizing the functions of system information integration, automatic control, intelligent monitoring, and big data statistics. In one embodiment, the electronic device 400 can be electrically connected to the power supply 250 and the spectrometer 350. The electronic device 400 is configured to synchronize the power supply 250 and the spectrometer 350 to synchronize the generation of plasma 120 and the reception of the emission spectrum, so as to achieve signal synchronization. This allows the time period during which the photodetector 300 receives the light signal to be synchronized with the time period during which the electrode 200 generates plasma 120, so as to effectively receive the light signal of the emission spectrum generated by plasma 120.

[0110] In one embodiment, the aforementioned electronic device 400 and external device can be a smartphone, desktop computer, laptop computer, tablet computer, workstation, server, cloud server, computing device, etc. The electronic device 400 and external device can also provide a user interface for user operation. The electronic device 400 and external device can also be indirectly operated or controlled through other electronic devices or external devices via telecommunication transmission. Furthermore, the electronic device 400, external device, or the aforementioned power supply 250, spectrometer 350, etc., can be further equipped with input modules and output modules to provide visual and / or auditory user interfaces, such as displays, touch screens, projectors, speakers, telephone voice input, keyboards, mice, touch screens, motion detection, voice recognition, etc., as a medium for control and setting.

[0111] In one embodiment, the aforementioned electrodes may be, for example, glass platinum electrodes and silver wire (CAS: 7440-22-4); the aforementioned optical fiber of the photodetector may be, for example, an FG600AEA manufactured by Thorlabs; the aforementioned power supply may be, for example, a PSW 800-4.32 manufactured by GWINSTEK; the aforementioned electronic device or circuit module may be, for example, an individual or combination of a Paspberry Pi 4 Model B / 8GB and an Arduino Uno R3 and an IGBT (Insulated Gate Bipolar Transistor): IXYP30N120C3; and the aforementioned spectrometer may be, for example, a 2030-025-FUV2A, Li-ion.

[0112] Figure 14 is a flowchart of the steps of a method for detecting substances in a liquid by plasma spectroscopy in an embodiment of the present disclosure; Figure 15 is a flowchart of the steps of a method for detecting substances in a liquid by plasma spectroscopy in an embodiment of the present disclosure.

[0113] Referring to Figure 14, another embodiment of this disclosure provides a method for detecting substances in a liquid by plasma spectroscopy. This method is suitable for operation with any of the apparatus or system described in the foregoing embodiments for detecting substances in a liquid by plasma spectroscopy, but is not limited thereto. The method includes: operation (S1410) providing an electrode in the liquid; operation (S1420) contacting the electrode with the liquid; operation (S1430) applying an external voltage to the liquid to generate plasma; and operation (S1440) detecting the emission spectrum generated by the plasma using a photodetector. The plasma generated in operation (S1430) is located within a bubble generated by the applied voltage; the photodetector in operation (S1440) is an optical fiber, and there is no focusing element between the photodetector and the plasma.

[0114] Therefore, by using optical fibers without focusing elements as photodetectors, the signal attenuation and interference of the plasma emission spectrum caused by optical phenomena such as varying bubble sizes, bubble movement and changes, bubble generation and destruction, and reflection and refraction at the gas-liquid interface caused by bubbles can be effectively eliminated when focusing and coupling light signals to the optical fiber using optical elements such as lenses. Furthermore, the emission spectrum signal of the plasma when the liquid to be tested is subjected to an applied voltage to generate plasma and bubbles can be effectively and completely collected, thereby obtaining effective and accurate analytical and detection results for various substances in the liquid to be tested.

[0115] Referring to Figure 15, in one embodiment, the operation (S1440) of detecting the emission spectrum generated by the plasma using a photodetector further includes: operation (S1441) disposing at least a portion of the photodetector in the liquid to be detected; operation (S1442) disposing the light-receiving end of at least a portion of the photodetector in a bubble; and operation (S1443) directly detecting the emission spectrum generated by the plasma in the bubble.

[0116] Therefore, when the receiving end of the optical fiber without a focusing element, which serves as a photodetector, is directly placed in the liquid to be detected, and the receiving end of the optical fiber, which serves as a photodetector, can be directly placed inside a bubble containing plasma, the influence of the bubble on the light receiving is minimized. The emission spectrum generated by the plasma in the bubble can be directly detected without being interfered with by any bubble or liquid, and the intensity and stability of the optical signal of the plasma emission spectrum are greatly improved.

[0117] In summary, the apparatus, system, and method for detecting substances in a liquid using plasma spectroscopy disclosed herein, by employing only an optical fiber as the photodetector without a focusing element, effectively eliminates and removes the significant interference and alteration of the light-gathering focus caused by optical phenomena such as varying bubble sizes, bubble movement and changes, bubble generation and destruction, bubble adhesion to the photodetector, and reflection and refraction at the gas-liquid interface caused by bubbles when focusing and coupling light signals to the optical fiber using lenses or other optical elements. This interference leads to signal attenuation and interference in the plasma emission spectrum. Furthermore, the optical fiber without a focusing element can effectively and completely collect the plasma emission spectrum signal of the liquid being tested when plasma and bubbles are generated under an applied voltage, thereby obtaining effective and accurate analysis and detection results for various substances in the liquid. Simultaneously, the simple relative arrangement of electrodes and the photodetector allows detection via plasma emission spectrum, while also offering advantages such as portability, small device size, ease of operation, low cost, simultaneous detection of multiple heavy metals, rapid detection, and minimal interference between different metals.

[0118] Furthermore, by placing at least a portion of an optical fiber without a focusing element, which serves as a photodetector, in the sample region, and positioning the receiving end of at least a portion of the photodetector directly within the bubble generation area, it is possible to directly detect the emission spectrum generated by the plasma within the bubble, without being affected by other bubbles or liquids. That is, when the optical fiber is brought close to the electrode at a sufficiently short distance without affecting plasma and bubble generation, in addition to retaining the original advantages of the optical fiber—being unaffected by the change in focus due to the bubble—the distance between the receiving end and the plasma can be reduced to decrease interference from various interfaces or signal absorption along the optical path. Moreover, when the receiving end of the optical fiber, serving as a photodetector, is sufficiently close to the electrode and its generated plasma, the receiving end of the fiber can be directly located within the bubble containing the plasma, thereby minimizing the bubble's influence on light collection and significantly improving the intensity and stability of the optical signal in the plasma emission spectrum. Furthermore, by bringing the optical fiber sufficiently close to the bubble, a surface cleaning effect can also be achieved during periods other than the detection of the plasma optical signal, as the bubble generates, disappears, and changes.

[0119] Furthermore, due to the system integration and ease of use of plasma spectroscopy for detecting substances in liquids, the device and system disclosed herein can be applied to various fields and situations. These include single-use testing in target water bodies, laboratory testing, and real-time, continuous, long-term monitoring in various environments and factories. The device can provide immediate test results, notifications, and alerts without requiring high equipment and personnel training costs, and without generating additional negative byproducts. Remote, programmable control also provides functions such as system information integration, automatic control, intelligent monitoring, and big data statistics.

[0120] This disclosure has been described above with reference to preferred embodiments. However, those skilled in the art should understand that the embodiments are for illustrative purposes only and should not be construed as limiting the scope of this disclosure. It should be noted that all variations and substitutions equivalent to the described embodiments should be considered within the scope of this disclosure, and the above embodiments can be combined and modified in any way. Therefore, the scope of protection of this disclosure is determined by the claims as defined in the claims.

Claims

1. A device for detecting substances in a liquid by plasma spectroscopy, characterized in that, include: An electrode, at least a portion of which is adapted to be disposed in and in contact with the liquid to be tested, the electrode being adapted to generate plasma in the liquid to be tested by an applied voltage, wherein the plasma is located in a bubble generated by the applied voltage; A photodetector adapted to detect the emission spectrum generated by plasma in the bubble, wherein the photodetector is an optical fiber and there is no focusing element between the photodetector and the plasma.

2. The apparatus for detecting a substance in a liquid to be detected by plasma spectroscopy according to claim 1, characterized by, At least a portion of the photodetector is adapted to be disposed in the liquid to be detected, and at least a portion of the photodetector includes a light-receiving end adapted to be located in the bubble to detect the emission spectrum generated by the plasma in the bubble.

3. The apparatus for detecting a substance in a liquid to be detected by plasma spectroscopy according to claim 1, characterized by, The photodetector is configured at a first angle relative to the normal direction of the contact surface between the electrode and the liquid to be detected, wherein the first angle is 0 degrees with the normal direction of the contact surface.

4. The apparatus for detecting a substance in a liquid to be detected by plasma spectroscopy according to claim 3, characterized by, At least a portion of the photodetector is adapted to be disposed in the liquid to be detected, and at least a portion of the photodetector includes a light-receiving end, the distance between the light-receiving end and the electrode being configured such that the light-receiving end is adapted to be located within the range of the bubble.

5. The apparatus for detecting a substance in a liquid to be detected by plasma spectroscopy according to claim 3, characterized by, At least a portion of the photodetector includes a light-receiving end, the distance between the light-receiving end and the electrode being between 0.1 mm and 4 mm.

6. The apparatus for detecting a substance in a liquid to be detected by plasma spectroscopy according to claim 1, wherein The photodetector is configured at a second angle relative to the normal direction of the contact surface between the electrode and the liquid to be detected, wherein the second angle is 90 degrees from the normal direction of the contact surface.

7. The device for detecting a substance in a liquid to be detected by plasma spectroscopy according to claim 6, characterized by, At least a portion of the photodetector is adapted to be disposed in the liquid to be detected, and at least a portion of the photodetector includes a light-receiving end, the distance between the light-receiving end and the electrode being configured such that the light-receiving end is adapted to be located within the range of the bubble.

8. The apparatus for detecting a substance in a liquid to be detected by plasma spectroscopy according to claim 6, characterized by, At least a portion of the photodetector includes a light-receiving end, the distance between the light-receiving end and the electrode being between 0.05 mm and 3.5 mm.

9. The apparatus for detecting a substance in a liquid to be detected by plasma spectroscopy according to claim 1, wherein The photodetector is configured at a third angle relative to the normal direction of the contact surface between the electrode and the liquid to be detected, wherein the angle between the third angle and the normal direction of the contact surface is between a first angle and a second angle, wherein the angle between the first angle and the normal direction of the contact surface is 0 degrees, and the angle between the second angle and the normal direction of the contact surface is 90 degrees.

10. The device for detecting a substance in a liquid to be detected by plasma spectroscopy according to claim 9, characterized by, At least a portion of the photodetector is adapted to be disposed in the liquid to be detected, and at least a portion of the photodetector includes a light-receiving end, the distance between the light-receiving end and the electrode being configured such that the light-receiving end is adapted to be located within the range of the bubble.

11. The apparatus for detecting a substance in a liquid to be detected by plasma spectroscopy according to claim 9, wherein At least a portion of the photodetector includes a light-receiving end, the distance between the light-receiving end and the electrode being between 0.05 mm and 3.5 mm.

12. The apparatus for detecting a substance in a liquid to be detected by plasma spectroscopy according to claim 1, wherein At least a portion of the photodetector is adapted to be disposed in the liquid to be detected, and at least a portion of the photodetector includes a light-receiving end, the distance between the light-receiving end and the electrode being between 0.05 mm and 10 mm.

13. A system for detecting substances in a liquid by plasma spectroscopy, characterized in that, include: The device for detecting a substance in a liquid to be detected according to any one of claims 1 to 12; a sample chamber configured to hold the electrode and the light detecting member, and adapted to receive the liquid to be detected; a spectrometer coupled to the light detecting member, the spectrometer configured to analyze a luminescence spectrum generated by the plasma in the bubble detected by the light detecting member; a power supply coupled to the electrode, the power supply configured to provide the applied voltage to the electrode.

14. The system for detecting a substance in a liquid to be detected by plasma spectroscopy according to claim 13, characterized by, Further comprising an electronic device electrically connected to the spectrometer, the electronic device configured to analyze the luminescence spectrum by the spectrometer.

15. The system for detecting a substance in a liquid to be detected by plasma spectroscopy according to claim 14, characterized by, The electronic device is configured to be signal-connected with an external device to provide an analysis result related to the luminescence spectrum of the liquid to be detected in real time.

16. The system for detecting a substance in a liquid to be detected by plasma spectroscopy according to claim 13, wherein Further comprising an electronic device electrically connected to the power supply, the electronic device configured to set a parameter of the applied voltage by the power supply to adjust the plasma generated in the liquid to be detected.

17. The system for detecting a substance in a liquid to be detected by plasma spectroscopy according to claim 13, wherein Further comprising an electronic device electrically connected to the power supply and the spectrometer, the electronic device configured to synchronize the power supply and the spectrometer to synchronize the generation of the plasma and the reception of the luminescence spectrum.

18. A method of detecting a substance in a liquid to be detected by plasma spectroscopy, characterized by, Comprising: providing an electrode in a liquid to be detected; contacting the electrode with the liquid to be detected; applying an applied voltage to generate a plasma in the liquid to be detected; detecting a luminescence spectrum generated by the plasma by a light detecting member, wherein the plasma is located in a bubble generated by the applied voltage, wherein the light detecting member is an optical fiber, and there is no light collecting element between the light detecting member and the plasma.

19. The method of claim 18, wherein the method further comprises: determining the presence of the substance in the liquid based on the detected plasma light spectrum. The operation of detecting a luminescence spectrum generated by the plasma by the light detecting member further comprises: configuring at least a part of the light detecting member in the liquid to be detected, and configuring a light receiving end included in at least a part of the light detecting member in the bubble, to directly detect a luminescence spectrum generated by the plasma in the bubble.

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