Device, system and method for detecting substances in a liquid to be tested using plasma spectroscopy

Abstract

The present invention provides an apparatus for detecting substances in a liquid by means of plasma spectroscopy, comprising: an electrode, at least a portion of which is adapted to be disposed in the liquid to be detected and adapted to be in contact with the liquid to be detected, the electrode being adapted to generate a plasma in the liquid to be detected by means of an applied voltage, wherein the plasma is located in a bubble generated by the applied voltage; and a photodetector adapted to detect a light 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.

Description

Technical Field

[0001] The present invention provides an apparatus, system and method for detecting substances in a liquid, particularly an apparatus, system and method for detecting substances in a liquid to be tested using plasma spectroscopy. Prior Technology

[0002] Water quality testing is used 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 applied in various occasions and fields, including environmental monitoring, hygiene monitoring, industrial safety monitoring, and production process monitoring, to detect the water quality of different bodies of water and, based on this, to understand 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.

[0003] To effectively meet the continuous monitoring needs of various fields, taking industrial fields as an example, online real-time heavy metal detection is very important in industrial applications. However, conventional online continuous heavy metal detection technologies for industrial use are not only expensive, but also often only detect a single metal per device, and have poor tolerance to interference from other substances. Furthermore, they 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 complicated operation, or are too expensive are also not suitable for carrying to various fields to monitor substances in aqueous solutions.

[0004] For example, experimental-level heavy metal detection methods such as Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) and Flame Atomic Absorption Spectroscopy (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 simple to operate. However, they are prone to interactions between metals, which can affect their detection signals.

[0005] 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

[0006] To address the aforementioned challenges in simultaneously achieving efficiency, speed, and accuracy in the detection of substances in aqueous solutions, one approach involves using aqueous plasma. This method generates plasma in an aqueous solution through electrodes, and the emission spectrum of the plasma is detected optically. The substances contained in the aqueous solution can then be determined by analyzing the emission spectrum of the plasma.

[0007] 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 sizes of bubbles, their movement and changes, their formation and destruction, and optical phenomena such as reflection and refraction caused by the gas-liquid interface all significantly affect the intensity and accuracy of the collected plasma emission spectrum signal. 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.

[0008] Therefore, the purpose of this invention 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 the existing aqueous plasma method, it is less affected by bubbles or aqueous solution characteristics, and can significantly improve the intensity and accuracy of plasma emission spectrum, thereby rapidly, effectively, and accurately detecting the types of substances in aqueous solutions.

[0009] In view of this, the present invention provides an apparatus, system and method for detecting substances in a liquid by means of plasma spectroscopy, so as to significantly improve the intensity and accuracy of plasma emission spectrum in aqueous plasma method.

[0010] One aspect of the present invention provides an apparatus for detecting substances in a liquid by means of plasma spectroscopy, comprising: an electrode, at least a portion of which is adapted to be disposed in the liquid to be detected and adapted to be in contact with the liquid to be detected, the electrode being adapted to generate a plasma in the liquid to be detected by means of an applied voltage, wherein the plasma is located in a bubble generated by the applied voltage; and a photodetector adapted to detect a light 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.

[0011] As described above, in the apparatus for detecting substances in a liquid by means of plasma spectroscopy, 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 a bubble to detect the emission spectrum generated by plasma in the bubble.

[0012] As described above, in the apparatus for detecting substances in a liquid by means of plasma spectroscopy, 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.

[0013] As described above, in the apparatus for detecting substances in a liquid by means of plasma spectroscopy, 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.

[0014] As described above, in the apparatus for detecting substances in a liquid by means of plasma spectroscopy, 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.

[0015] As described above, in the apparatus for detecting substances in a liquid by means of plasma spectroscopy, the photodetector is configured at a second angle relative to the normal direction of the contact surface between the electrode and the liquid, wherein the second angle is 90 degrees from the normal direction of the contact surface.

[0016] As described above, in the apparatus for detecting substances in a liquid by means of plasma spectroscopy, 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.

[0017] As described above, in the apparatus for detecting substances in a liquid by means of plasma spectroscopy, 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.

[0018] As described above, in the device for detecting substances in a liquid by means of 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 to be detected. The angle between the third angle and the normal direction of the contact surface is between a first angle and a second angle. The first angle is 0 degrees and the angle between the first angle and the normal direction of the contact surface is 90 degrees.

[0019] As described above, in the apparatus for detecting substances in a liquid by means of plasma spectroscopy, 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.

[0020] As described above, in the apparatus for detecting substances in a liquid by means of plasma spectroscopy, 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.

[0021] As described above, in the apparatus for detecting substances in a liquid by means of plasma spectroscopy, 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.

[0022] One embodiment of the present invention 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, the spectrometer being configured to analyze the emission spectrum generated by plasma detected by the photodetector within the bubbles; and a power supply coupled to the electrodes, the power supply being configured to provide an applied voltage to the electrodes.

[0023] 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.

[0024] As described above, in the system for detecting substances in a liquid using plasma spectroscopy, the electronic device is configured to be signal-connected to an external device to provide real-time analysis results of the emission spectrum associated with the liquid being detected.

[0025] The system for detecting substances in a liquid as described above via plasma spectroscopy also includes an electronic device electrically connected to a power source. The electronic device is configured to set the parameters of the applied voltage via the power source to adjust the plasma generated in the liquid to be detected.

[0026] The system for detecting substances in a liquid by means of plasma spectroscopy, as described above, also includes an electronic device electrically connected to a power supply and a spectrometer. The electronic device is configured to synchronize the power supply and the spectrometer to synchronize the generation of plasma and the reception of the emission spectrum.

[0027] One aspect of the present invention provides a method for detecting a substance in a liquid by means of plasma spectroscopy, comprising: providing an electrode in a liquid to be detected; contacting the electrode with the liquid to be detected; applying an external voltage to generate a plasma in the liquid to be detected; and detecting a emission spectrum generated by the plasma through 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.

[0028] As described above, the method for detecting substances in a liquid by means of plasma spectroscopy includes, in which the operation of detecting the emission spectrum generated by plasma by means of a photodetector further includes: placing at least a portion of the photodetector in the liquid to be detected, and placing a light-receiving end of at least a portion of the photodetector in a bubble, so as to directly detect the emission spectrum generated by plasma in the bubble.

[0029] The apparatus, system, and method for detecting substances in a liquid using plasma spectroscopy, as described in this invention, utilizes an optical fiber without a focusing element for the photodetector. This effectively eliminates and removes signal attenuation and interference from 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 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 some liquid components. Therefore, it can effectively and completely collect the plasma emission spectrum signal when the liquid to be tested is subjected to an applied voltage to generate plasma and bubbles, thereby obtaining effective and accurate analytical and detection results for various substances in the liquid. Furthermore, the simple relative arrangement of the 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. Simple Explanation of the Diagram

[0030] Figure 1A shows a schematic diagram of the configuration of a plasma detection device with a solution external lens group for light collection, as is known in the prior art; Figure 1B shows a schematic diagram of the configuration of a plasma detection device for receiving light using an intra-solution lens group, as is known in the prior art; Figure 1C shows a schematic diagram of the signal trend obtained by a plasma detection device using a conventional solution-based lens group for light collection in the prior art; Figure 2A shows a schematic diagram of the configuration of a device for detecting substances in a liquid by means of plasma spectroscopy in an embodiment of the present invention; Figure 2B shows a schematic diagram of the configuration of a device for detecting substances in a liquid by means of plasma spectroscopy in an embodiment of the present invention; Figure 3 shows a schematic comparison of the signal intensities obtained by devices using prior art and those using plasma spectroscopy to detect substances in a liquid according to embodiments of the present invention; Figure 4 shows a comparative schematic diagram of the spectral distributions obtained by using prior art and by using the apparatus for detecting substances in a liquid by plasma spectroscopy in an embodiment of the present invention; Figure 5A shows a schematic diagram of the configuration of a device for detecting substances in a liquid by means of plasma spectroscopy in an embodiment of the present invention; Figure 5B shows a schematic diagram of the configuration of a device for detecting substances in a liquid by means of plasma spectroscopy in an embodiment of the present invention; Figure 6A shows a schematic diagram comparing the spectral intensities obtained at different distances between the photodetector and the electrode in one embodiment of the present invention; Figure 6B shows a schematic diagram comparing the spectral intensities obtained at different distances between the photodetector and the electrode in one embodiment of the present invention; Figure 7A shows a schematic diagram of different angles between the photodetector and the electrode in one embodiment of the present invention; Figure 7B shows a schematic diagram comparing the spectral intensities obtained at different angles between the photodetector and the electrode in one embodiment of the present invention; Figure 7C shows a schematic diagram comparing the spectral intensities obtained at different angles between the photodetector and the electrode in one embodiment of the present invention; Figure 8 shows a schematic diagram of the spectral intensities obtained by applying different external voltages to the electrodes in one embodiment of the present invention; Figure 9 shows a schematic diagram of the spectral intensities obtained using different electrode sizes in one embodiment of the present invention; Figure 10 shows a schematic diagram of the spectral intensities obtained by applying different pulse durations to the electrode in one embodiment of the present invention; Figure 11 shows a schematic diagram of the configuration of a system for detecting substances in a liquid by means of plasma spectroscopy according to an embodiment of the present invention; Figure 12 shows a schematic diagram of the configuration of a system for detecting substances in a liquid by means of plasma spectroscopy according to an embodiment of the present invention; Figure 13 shows a schematic diagram of the configuration of a system for detecting substances in a liquid by means of plasma spectroscopy according to an embodiment of the present invention; Figure 14 shows a flowchart of the steps of a method for detecting substances in a liquid by plasma spectroscopy according to an embodiment of the present invention; Figure 15 shows a flowchart of the steps of a method for detecting substances in a liquid by means of plasma spectroscopy in an embodiment of the present invention. Implementation

[0031] To illustrate the technical content of this invention 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.

[0032] To fully understand the purpose, features and effects of the present invention, the present invention will be described in detail below with reference to the following specific embodiments and accompanying drawings.

[0033] Figure 1A shows a schematic diagram of the configuration of a plasma detection device that receives light from an external lens group in the prior art; Figure 1B shows a schematic diagram of the configuration of a plasma detection device that receives light from an internal lens group in the prior art; Figure 1C shows a schematic diagram of the signal trend obtained by using a plasma detection device that receives light from an internal lens group in the prior art.

[0034] Please refer to Figures 1A and 1B. In the prior art, it is known that the aqueous plasma method is used as a detection device for detecting the elemental analysis of substances in aqueous solutions. It can be divided into two types: a method in which the photodetector is placed outside the aqueous solution and the lens group is used to collect light outside the solution (as shown in Figure 1A), and a method in which the photodetector is placed in the aqueous solution and the lens group is used to collect light underwater (as shown in Figure 1B).

[0035] In the conventional plasma detection device 80 with external lens assembly for light collection shown in Figure 1A, an electrode 820 is provided immersed in the liquid 801 to be detected, and a photodetector 830 is provided outside the liquid 801 to prevent interference and damage to the photodetector 830 by the liquid 801. In order to achieve accurate and effective light collection, a focusing element 831 is conventionally provided 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 present in the liquid 801, such as heavy metals.

[0036] 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 destruction of these bubbles 803 affect the optical path of the light-receiving area 832 determined by the focusing element 831. In addition to the generation and destruction of bubbles 803, uncertainties such as the different sizes of bubbles 803, the movement of bubbles 803, and the optical characteristics 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, thereby causing interference and difficulties in subsequent material analysis. It should be noted that, for clarity, a plurality of bubbles of different sizes and uncertainties are not shown in Figure 1A. In reality, there may be a plurality of bubbles of different sizes and behaviors in the light-receiving area 832.

[0037] In the conventional plasma detection device 90 for light collection by an intra-solution lens assembly shown in Figure 1B, both the photodetector 930 and the electrode 920 are immersed in the liquid to be tested 901 in an attempt to reduce the influence of the bubble 903 on the light collection area 932.

[0038] 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.

[0039] Please refer to Figure 1C. When using a conventional plasma detection device with a solution-based lens assembly for light collection, the trend of signal intensity received by the photodetector over time is shown in Figure 1C. Due to the aforementioned factors of large-scale bubble generation and interference, as the plasma generation time progresses, a large number of bubbles will also be generated, affecting the light-collecting optical path and causing the signal intensity to decrease significantly over time. This significantly affects the signal intensity and signal resolution of the collected plasma emission spectrum.

[0040] Figure 2A shows a schematic diagram of the configuration of an apparatus for detecting substances in a liquid by means of plasma spectroscopy in an embodiment of the present invention; Figure 2B shows a schematic diagram of the configuration of an apparatus for detecting substances in a liquid by means of plasma spectroscopy in an embodiment of the present invention.

[0041] Please refer to Figure 2A. To address the problems of reduced signal strength and resolution caused by air bubbles, one embodiment of the present invention is 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.

[0042] At least a portion of electrode 200 is disposed within 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 within 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 at 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, for example, be a coaxial cylindrical structure. The conductive portion 210 is, for example, encased within 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, the electrode 200 referred to herein is 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, for example, be configured to be immersed in the liquid to be tested. In one embodiment, the other end of electrode 200 that is in contact with the liquid 110 to be tested 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.

[0043] The photodetector 300 is adapted to detect the emission spectrum generated by the plasma 120 within 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 along 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 this embodiment of the invention, 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 coupler. 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 emission spectrum signal 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 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.

[0044] 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, the external signal connections and fixing methods of 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 wired or wireless communication for signal transmission.

[0045] Therefore, through the device 11 shown in Figure 2A, which detects substances in a liquid by means of 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, since no focusing element is used, the light-receiving range of the photodetector 300 will not be overly focused on the optical focal point. Therefore, when a large number of bubbles 130 are generated, moved, and changed randomly, the one or more bubbles 130 will not significantly affect the focal point position and cause the light-receiving range to deviate from the actual position of the plasma 120. This allows for the effective collection of light signals generated by the plasma 120, greatly improving the signal intensity, signal resolution, and accuracy of detecting the emission spectrum of the plasma 120.

[0046] Please refer to Figure 2B. The device 12 for detecting substances in a liquid using plasma spectroscopy shown in Figure 2B is largely the same as the device 11 for detecting substances in a liquid using 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 electrode 200 generates the plasma 120, 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 upwards, the photodetector 300 positioned 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 positioned 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 closer, the photodetector 300 positioned 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.

[0047] Figure 3 shows a comparative schematic diagram of the signal intensity obtained using the prior art (the conventional plasma detection device 80 with an external lens group for light collection shown in Figures 1A and 1B, and the conventional plasma detection device 90 with an internal lens group for light collection shown in Figures 2A and 2B respectively) and the device for detecting substances in the liquid to be detected by plasma spectroscopy in the embodiment of the present invention (11 in Figure 2A is axially arranged, and 12 in Figure 2B is radially arranged); Figure 4 shows a comparative schematic diagram of the spectral distribution obtained using the prior art (the conventional plasma detection device 80 with an external lens group for light collection shown in Figures 1A and 1B, and the conventional plasma detection device 90 with an internal lens group for light collection shown in Figures 1A and 2B respectively) and the device for detecting substances in the liquid to be detected by plasma spectroscopy in the embodiment of the present invention (11 in Figure 2A is axially arranged, and 12 in Figure 2B is radially arranged).

[0048] Please refer to Figure 3, which shows an experimental comparison 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 the present invention.

[0049] As can be seen from the fourth column of Figure 3, when a lens group conventionally positioned outside the liquid to be detected is used as the 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 drastic changes in the signal received by the lens group, resulting in poor stability.

[0050] As shown in the third column of Figure 3, when a conventional underwater lens assembly placed in the liquid to be detected is used as the 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 attempt 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 assembly, which similarly affects the optical path of the collected plasma. Furthermore, since the underwater lens assembly is located underwater, bubbles will adhere to its surface over time, further affecting the light collection efficiency and accuracy. As can be seen in the table, compared with other comparison groups, the signal intensity of the underwater lens assembly decreases significantly over time as plasma generation progresses, significantly affecting the signal intensity and signal resolution of the emission spectrum within the collected plasma.

[0051] As can be seen from the second column of Figure 3, when the optical fiber without a focusing element provided by an embodiment of the present invention is used as a photodetector and light is collected in the radial direction, the signal intensity is approximately between 21,000 a.u. and 27,000 a.u., and the RSD is 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 conventional lens groups and underwater lenses, which also collect light radially but with poor results, the radial light collection of the optical fiber of the present invention (as shown in Figure 2B-12) 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.

[0052] As can be seen from the first column of Figure 3, when the optical fiber without a focusing element provided by an embodiment of the present invention is used as the photodetector and light is collected in a short-distance axial direction, the signal intensity is approximately between 38,000 a.u. and 46,000 a.u., and the RSD is 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 due to the bubble, the distance between the light-receiving end and the plasma can be reduced to reduce interference between the 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.

[0053] Figure 4 shows 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 conventional lens groups and underwater lenses are examined under the same conditions with those of the optical fiber radial and short-distance optical fiber axial without a focusing element provided by the present invention, 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 by the present invention is significantly better than that of conventional lens groups and underwater lenses in all wavelength bands, except for a single peak. This demonstrates the significant advantage of the device for detecting substances in a liquid through plasma spectroscopy provided by the present invention in using an optical fiber without a focusing element as a photodetector. Furthermore, in one embodiment, taking the presence of zinc (Zn) in the liquid to be detected as an example, compared to conventional lens groups and underwater lenses, the use of radial optical fibers without focusing elements or short-distance axial optical fibers as light detectors in the embodiments of the present invention can better detect the signal emitted by zinc (as indicated by the arrow) in the liquid to be detected in the spectrum.

[0054] Figure 5A shows a schematic diagram of the configuration of an apparatus for detecting substances in a liquid by means of plasma spectroscopy in an embodiment of the present invention; Figure 5B shows a schematic diagram of the configuration of an apparatus for detecting substances in a liquid by means of plasma spectroscopy in an embodiment of the present invention.

[0055] 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.

[0056] By placing one end of the photodetector 300 directly in the sample region 100 and placing the light-receiving end 320 of the photodetector 300 directly near the electrode 200 to the position of the plasma 120 generated by the electrode 200, the light-receiving end 320 can be directly positioned within the bubble 130 containing the plasma 120. This minimizes the influence of the bubble 130 and its interface on 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 affected by any interference or influence from other bubbles. This also minimizes the noise contribution or influence of other gas-liquid interfaces on the background, and prevents the absorption of some 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 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, for example, 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.

[0057] 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.

[0058] Therefore, compared to the device 51 for detecting substances in a liquid using plasma spectroscopy shown in Figure 5A, where the photodetector 300 is axially positioned on the front of the electrode 200, the device 52 for detecting substances in a liquid using plasma spectroscopy shown in Figure 5B has its photodetector 300 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 (as shown in Figure 5A, 51) 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 (Figure 5A-51), the axially arranged photodetector 300 (Figure 5B-52) is less susceptible to the influence of other background factors. Therefore, the axially arranged photodetector 300 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, thus also providing higher signal strength and stability.

[0059] Figures 6A and 6B respectively show schematic diagrams comparing the spectral intensities obtained at different distances between the photodetector and the electrode in the embodiments of the present invention.

[0060] Please refer to Figure 6A. Figure 6A shows 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) when the photodetector 300 is arranged in the axial direction (as shown in 51 of Figure 5A) in one embodiment. Figure 6B shows 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) when the photodetector 300 is arranged in the axial direction (as shown in 51 of Figure 5A) in one embodiment. 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 brings significant benefits.

[0061] Figure 7A shows a schematic diagram of the configuration of the photodetector and the electrode at different angles in an embodiment of the present invention; Figure 7B shows a schematic diagram comparing the spectral intensities obtained at different angles between the photodetector and the electrode in an embodiment of the present invention; Figure 7C shows a schematic diagram comparing the spectral intensities obtained at different angles between the photodetector and the electrode in an embodiment of the present invention.

[0062] Please refer to Figure 7A, which illustrates the configuration of the photodetector 300 relative to the electrode 200 at three angles: a first angle A1, a second angle A2, and a third angle A3. 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 position of the first angle A1, the photodetector 300 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 set at a second angle A2, where the angle between the second angle A2 and the normal direction of the contact surface is 90 degrees. That is, when the photodetector 300 is located at the first angle A1, 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 set 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.

[0063] Please refer to Figure 7A. As shown in Figure 7A, when the photodetector 300 is set 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 close distance, and thus may hinder 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 light-receiving end 320 of the photodetector 300 is close enough to the electrode 200 without affecting the generation of the bubble 130 or the 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 by the generation or change of other bubbles, and without being interfered by the absorption of water or the liquid to be detected, thereby greatly improving the light-receiving intensity and accuracy. Therefore, this is the optimal light-receiving distance for the photodetector 300. Subsequently, in Region III, as the light-receiving end 320 gradually moves away from the electrode 200 and the plasma 120 it generates, the light-receiving end 320 of the photodetector 300 has detached from the bubble 130 containing the plasma 120 and begins to be affected by other bubbles or liquids. However, since the photodetector 300 uses an optical fiber, the emission spectrum signal generated by the plasma 120 is not 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, although the photodetector 300 is less likely to be attached to by other bubbles, the increased distance increases the absorption by water or the liquid to be detected. However, compared to conventional light-receiving methods, the use of optical fiber still maintains a certain degree of effective light collection and is not severely affected by the conventional change in focus.

[0064] 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 preferable that at least a portion of the photodetector 300 is disposed within the sample region 100, and that 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 adapted 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 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.

[0065] 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 suitably positioned 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.

[0066] 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 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 suitably positioned 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 similar 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.

[0067] Next, please refer to Figures 7B and 7C. As can be seen from the comparison diagram of the spectral intensity obtained at different angles shown 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.

[0068] Figure 8 shows a schematic diagram of the spectral intensities obtained by applying different external voltages to the electrodes in one embodiment of the present invention.

[0069] Please refer to Figure 8, which shows an experimental schematic diagram of 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.

[0070] Figure 9 shows a schematic diagram of the spectral intensities obtained using different electrode sizes in one embodiment of the present invention.

[0071] Please refer to Figure 9, which shows the experimental schematic diagram of 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 of Figure 9 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.

[0072] Figure 10 shows a schematic diagram of the spectral intensities obtained by applying different pulse times to the electrodes in one embodiment of the present invention.

[0073] Please refer to Figure 10. Figure 10 shows an experimental schematic diagram of 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 when the on-time is 800 ms and the off-time is 3000 ms; the lower part of Figure 10 shows the spectral intensity distribution when the on-time is 0.5 ms and the off-time is 0.5 ms. Under these conditions, 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 plasma emission spectra generated under the conditions of on-time 800 ms, off-time 3000 ms, and on-time 0.5 ms and off-time, respectively, still retain the main characteristics of their respective wavelengths after reception.

[0074] In summary, the device for detecting substances in a liquid by plasma spectroscopy provided in one embodiment of the present invention 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.

[0075] Figure 11 shows a schematic diagram of the configuration of a system for detecting substances in a liquid by means of plasma spectroscopy in an embodiment of the present invention.

[0076] Another aspect of the present invention 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.

[0077] 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 structure machined 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.

[0078] 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 within 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 can thereby analyze and obtain 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 concerning the photodetector 300, the spectrometer 350, and the connections between them are for illustrative purposes only and do not represent actual physical or spatial differences or sizes. Furthermore, the sizes and proportions of the bubble 130, plasma 120, electrode 200, and photodetector 300 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.

[0079] 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 tested. In one embodiment, the power supply 250 can be a power supply, a function generator, a pulse generator, a high-voltage function generator, etc., which can supply 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 for illustrative purposes only and do not represent actual physical or spatial differences in size or distance, nor do they represent actual size proportions.

[0080] Figure 12 shows a schematic diagram of the configuration of a system 22 for detecting substances in a liquid by means of plasma spectroscopy in an embodiment of the present invention; Figure 13 shows a schematic diagram of the configuration of a system 23 for detecting substances in a liquid by means of plasma spectroscopy in an embodiment of the present invention.

[0081] Please refer to Figures 12 and 13. In one embodiment, the system 22 of the present invention for detecting substances in a liquid by means of plasma spectroscopy may further include an electronic device 400. The electronic device 400 is configured to be electrically connected to the spectrometer 350 and configured to further analyze the information of the emission spectrum generated by the plasma 120 through the spectrometer 350.

[0082] In one embodiment, the electronic device 400 is further configured to be signal-connected to an external device (not shown) to provide real-time analysis results of the emission spectrum of the liquid 110 to the external device. In one embodiment, the external device may be further connected to other external electronic devices, such as a user's computer, mobile phone, or monitoring systems in a home, company, factory, or government unit, to provide real-time information on the detection results of the liquid 110 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 immediately to address the relevant water pollution situation. Thus, the device and system for detecting substances in a liquid using plasma spectroscopy of the present invention 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.

[0083] In one embodiment, the system 23 for detecting substances in a liquid using plasma spectroscopy may also include an electronic device 400 configured to be electrically connected to a power supply 250 and configured to set 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 may not be 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.

[0084] 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 provided with input modules and output modules to provide visual and / or auditory user interfaces, such as displays, touch screens, projectors, speakers, telephone voice, keyboards, mice, touch screens, motion detection, voice recognition, etc., as a medium for control and setting.

[0085] 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, a combination of Paspberry Pi 4 Model B / 8GB, Arduino Uno R3, and IGBT (Insulated Gate Bipolar Transistor): IXYP30N120C3; the aforementioned spectrometer may be, for example, 2030-025-FUV2A, Li-ion.

[0086] Figure 14 shows a flowchart of the steps of a method for detecting substances in a liquid by plasma spectroscopy in an embodiment of the present invention; Figure 15 shows a flowchart of the steps of a method for detecting substances in a liquid by plasma spectroscopy in an embodiment of the present invention.

[0087] Referring to Figure 14, another embodiment of the present invention provides a method for detecting substances in a liquid using plasma spectroscopy. This method is suitable for operation with any of the aforementioned embodiments of the apparatus or system for detecting substances in a liquid using plasma spectroscopy, but is not limited thereto. The method includes: operation (S1410) providing an electrode in the liquid to be detected; operation (S1420) contacting the electrode with the liquid to be detected; operation (S1430) applying an external voltage to generate plasma in the liquid to be detected; and operation (S1440) detecting the emission spectrum generated by the plasma using a photodetector. In operation (S1430), the plasma generated is located within bubbles generated by the applied voltage; and in operation (S1440), the photodetector is an optical fiber, and there is no focusing element between the photodetector and the plasma.

[0088] Therefore, by using optical fibers without focusing elements as photodetectors, the signal attenuation and interference of plasma luminescence 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 plasma luminescence spectrum signal of the liquid being tested, generated by an applied voltage, can be effectively and completely collected, thereby obtaining effective and accurate analytical and detection results for various substances in the liquid.

[0089] Referring to Figure 15, in one embodiment, the operation (S1440) of detecting the emission spectrum generated by plasma through the light detector further includes: operation (S1441) disposing at least a portion of the light detector in the liquid to be detected; operation (S1442) disposing the light-receiving end of at least a portion of the light detector in the bubble; and operation (S1443) directly detecting the emission spectrum generated by the plasma in the bubble.

[0090] 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 light signal of the plasma emission spectrum are greatly improved.

[0091] In summary, the apparatus, system, and method for detecting substances in a liquid using plasma spectroscopy of the present invention, by using 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 optical elements such as lenses. This interference leads to a weakening and interference of the plasma emission spectrum signal. Furthermore, by using an optical fiber without a focusing element, the emission spectrum signal of the plasma when the liquid to be tested is subjected to an applied voltage and generates plasma and bubbles can be effectively and completely collected, thereby obtaining effective and accurate analysis and detection results for various substances in the liquid to be tested. Meanwhile, detection can be completed through the emission spectrum of plasma by simply setting up the electrodes and photodetectors. It also has the advantages of being portable, small in size, easy to operate, low in cost, capable of detecting multiple heavy metals at the same time, rapid detection, and less likely to interfere with each other between different metals.

[0092] Furthermore, by placing at least a portion of an optical fiber (without a focusing element) serving as a photodetector within 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 of plasma generated 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, it retains the advantages of the original optical fiber, being unaffected by the focus being altered by the bubble. It also reduces the distance between the receiving end and the plasma, minimizing interference from various interfaces or signal absorption along the optical path. Moreover, when the receiving end of the optical fiber serving as the 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 influence of the bubble on light collection and significantly improving the intensity and stability of the plasma emission spectrum. Furthermore, by bringing the optical fiber close enough to the bubble, the surface cleaning effect of the optical fiber can also be achieved during periods other than when detecting plasma light signals, as the bubble is generated, disappears, and changes.

[0093] Furthermore, by integrating a system for detecting substances in a liquid using plasma spectroscopy and leveraging the simplicity of the device, the apparatus and system of this invention can be applied to various fields and situations. These include being easily portable to the target water body for single-use testing, conducting tests in a laboratory, or being installed in various environments and factories for real-time, continuous, long-term monitoring. The system 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.

[0094] The present invention has been disclosed above with reference to preferred embodiments. However, those skilled in the art should understand that these embodiments are merely illustrative of the invention and should not be construed as limiting its scope. It should be noted that all variations and substitutions equivalent to these embodiments should be considered within the scope of the present invention, and the above embodiments can be combined and modified in any way. Therefore, the scope of protection of the present invention should be determined by the claims as defined in the patent applications.

[0095] 11: A device for detecting substances in a liquid using plasma spectroscopy. 12: A device for detecting substances in a liquid using plasma spectroscopy. 21: A system for detecting substances in a liquid using plasma spectroscopy 22: A system for detecting substances in a liquid using plasma spectroscopy 23: A system for detecting substances in a liquid using plasma spectroscopy. 51: A device for detecting substances in a liquid using plasma spectroscopy. 52: A device for detecting substances in a liquid using plasma spectroscopy. 100: Sample area 110: Liquid to be tested 120: Plasma 130: Bubbles 150: Sample Chamber 200: Electrode 210: Conductive part 220: Insulation section 250: Power Supply 300: Optical Detection Component 310: Light-receiving area 320: Receiver 350: Spectrometer 400: Electronic Devices 80: Conventional plasma detection device using external lens group for light collection in a solution 801: Liquid to be tested 802: Plasma 803: Bubbles 820: Electrode 830: Optical Detection Component 831: Concentrating element 832: Light-receiving area 90: A conventional plasma detection device using a lens group within a solution for light collection. 901: Liquid to be tested 902: Plasma 903: Bubbles 920: Electrode 930: Optical Detection Device 931: Concentrating element 932: Light-receiving area A1: First Angle A2: Second angle A3: Third Angle I, II, III, IV: Regions S1410~S1440: Operation S1441~S1443: Operation

Claims

1. An apparatus for detecting a substance in a liquid by plasma spectroscopy, comprising: an electrode, at least a portion of which is adapted to be disposed in and in contact with the liquid, the electrode being adapted to generate a plasma in the liquid by an applied voltage, wherein, The plasma is located within a bubble generated by the applied voltage; and a photodetector adapted to detect a light emission spectrum generated by the plasma within the bubble, wherein the photodetector is an optical fiber and there is no focusing element between the photodetector and the plasma; wherein 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, and 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 0.1 mm and 4 mm.

2. The apparatus for detecting a substance in a liquid as described in claim 1 via plasma spectroscopy, wherein, The distance between the light-receiving end and the electrode is configured such that the light-receiving end is positioned within the range of the bubble.

3. An apparatus for detecting a substance in a liquid by plasma spectroscopy, comprising: an electrode, at least a portion of which is adapted to be disposed in and in contact with the liquid, the electrode being adapted to generate a plasma in the liquid by an applied voltage, wherein, The plasma is located within a bubble generated by the applied voltage; and a photodetector adapted to detect a light emission spectrum generated by the plasma within the bubble, wherein the photodetector is an optical fiber and there is no focusing element between the photodetector and the plasma; 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 with the normal direction of the contact surface, and 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.

4. The apparatus for detecting a substance in a liquid by plasma spectroscopy as described in claim 3, wherein, The distance between the light-receiving end and the electrode is configured such that the light-receiving end is positioned within the range of the bubble.

5. An apparatus for detecting a substance in a liquid by plasma spectroscopy, comprising: an electrode, at least a portion of which is adapted to be disposed in and in contact with the liquid, the electrode being adapted to generate a plasma in the liquid by an applied voltage, wherein, The plasma is located within a bubble generated by the applied voltage; and a photodetector adapted to detect a light emission spectrum generated by the plasma within the bubble, wherein the photodetector is an optical fiber and there is no focusing element between the photodetector and the plasma; 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 first angle is 0 degrees and the angle between the first angle and the normal direction of the contact surface is 90 degrees, and 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.

6. The apparatus for detecting a substance in a liquid by plasma spectroscopy as described in claim 5, wherein, The distance between the light-receiving end and the electrode is configured such that the light-receiving end is positioned within the range of the bubble.

7. An apparatus for detecting a substance in a liquid by plasma spectroscopy, comprising: an electrode, at least a portion of which is adapted to be disposed in and in contact with the liquid, the electrode being adapted to generate a plasma in the liquid by an applied voltage, wherein, The plasma is located within a bubble generated by the applied voltage; and a photodetector adapted to detect a light emission spectrum generated by the plasma within the bubble, wherein the photodetector is an optical fiber and there is no focusing element between the photodetector and the plasma; 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.

8. A system for detecting a substance in a liquid by plasma spectroscopy, comprising: an apparatus for detecting a substance in a liquid by plasma spectroscopy as described in any one of claims 1 to 7; a sample chamber configured to hold the electrode and the photodetector and adapted to receive the liquid to be detected; a spectrometer coupled to the photodetector, the spectrometer being configured to analyze the emission spectrum of plasma detected by the photodetector within the bubble; and a power supply coupled to the electrode, the power supply being configured to provide the applied voltage to the electrode.

9. The system for detecting a substance in a liquid by plasma spectroscopy as described in claim 8, further comprising an electronic device electrically connected to the spectrometer, the electronic device being configured to analyze the emission spectrum by the spectrometer.

10. A system for detecting a substance in a liquid by plasma spectroscopy as described in claim 9, wherein, The electronic device is configured to connect to an external device to provide real-time analysis results of the emission spectrum associated with the liquid being tested.

11. The system for detecting a substance in a liquid to be tested by plasma spectroscopy as described in claim 8, further comprising an electronic device electrically connected to the power source, the electronic device being configured to set parameters of the applied voltage via the power source to adjust the plasma generated in the liquid to be tested.

12. The system for detecting a substance in a liquid by means of plasma spectroscopy as described in claim 8, further comprising an electronic device electrically connected to the power supply and the spectrometer, the electronic device being configured to synchronize the power supply and the spectrometer to synchronize the generation of plasma and the reception of the emission spectrum.

13. A method for detecting a substance in a liquid to be tested using plasma spectroscopy, comprising: providing an electrode in a liquid to be tested; contacting the electrode with the liquid to be tested; applying an external voltage to generate a plasma in the liquid to be tested; and detecting an emission spectrum generated by the plasma using a photodetector, wherein, The plasma is located within a bubble generated by the applied voltage. The photodetector is an optical fiber, and there is no focusing element between the photodetector and the plasma. 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.

14. The method for detecting a substance in a liquid by plasma spectroscopy as described in claim 13, wherein, The operation of detecting the emission spectrum generated by the plasma through the photodetector further includes: placing the light-receiving end in the bubble to directly detect the emission spectrum generated by the plasma in the bubble.

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