An optical sensing device and system for detecting the ph of a deep-sea environment

Abstract

The application provides a kind of deep sea environment pH optical sensing detection device and system, it is related to marine sensor field.The application provides a kind of deep sea environment pH optical sensing detection device and system, it is related to marine sensor field.The application provides a kind of deep sea environment pH optical sensing detection device and system, it is related to marine sensor field.The application provides a kind of deep sea environment pH optical sensing detection device and system, it is related to marine sensor field.The application provides a kind of deep sea environment pH optical sensing detection device and system, it is related to marine sensor field.The application provides a kind of deep sea environment pH optical sensing detection device and system, it is related to marine sensor field.The application provides a kind of deep sea environment pH optical sensing detection device and system, it is related to marine sensor field.The application provides a kind of deep sea environment pH optical sensing detection device and system, it is related to marine sensor field.The application provides a kind of deep sea environment pH optical sensing detection device and system, it is related to marine sensor field.The application provides a kind of deep sea environment pH optical sensing detection device and system, it is related to marine sensor field.The application provides a kind of deep sea environment pH optical sensing detection device and system, it is related to marine sensor field.The application provides a kind of deep sea environment pH optical sensing detection device and system, it is related to marine sensor field.The application provides a kind of deep sea environment pH optical sensing detection device and system, it is related to marine sensor field.The application provides a kind of deep sea environment pH optical sensing detection device and system, it is related to marine sensor field.The application provides a kind of deep sea environment pH optical sensing detection device and system, it is related to marine sensor field.The application provides a kind of deep sea environment pH optical sensing detection device and system, it is related to marine sensor field.The application provides a kind of deep sea environment pH optical sensing detection device and system, it is related to marine sensor field.The application provides a kind of deep sea environment pH optical sensing detection device and system, it is related to marine sensor field.The application provides a kind of deep sea environment pH optical sensing detection device and system, it is related to marine sensor field.The application provides a kind of deep sea environment pH optical sensing detection device and system, it is related to marine sensor field.The application provides a kind of deep sea environment pH optical sensing detection device and system, it is related to marine sensor field.The application provides a kind of deep sea environment pH optical sensing detection device and system, it is related to marine sensor field.The application provides a kind of deep sea environment pH optical sensing detection device and system, it is related to marine sensor field.The application

Description

Technical Field

[0001] This invention relates to the field of marine sensors, and more specifically, to an optical sensing device and system for detecting the acidity and alkalinity of deep-sea environments. Background Technology

[0002] The pH value of the deep-sea environment can affect metal solubility, mineral precipitation-dissolution balance, and microbial activity, and control deep-sea mineralization processes. Therefore, achieving high-precision, continuous, and real-time monitoring of deep-sea pH values ​​has become an urgent need in the field of deep-sea exploration and resource discovery.

[0003] During deep-sea exploration, sensing and detection devices must operate in a completely sealed environment to prevent damage to internal core components from high pressure and corrosive media. Therefore, the sensing system must be integrated into a pressure-resistant, sealed device, which places stringent requirements on the system's pressure resistance and resistance to marine corrosion. Current pH sensors mostly use glass electrodes, offering high measurement accuracy, but they are expensive and susceptible to seawater electrochemical corrosion and interference from the complex electromagnetic environment of the deep sea. They also pose potential failure risks such as electrolyte leakage and electrode contamination, making them unsuitable for long-term stable monitoring. In contrast, optical pH sensors employ an all-solid-state optical element design with no moving mechanical parts and no risk of liquid-filled cavities or electrolyte leakage. Their detection principle based on optical signal response completely avoids electrochemical interference, exhibiting stronger environmental adaptability and long-term stability, making them more suitable for continuous, long-term in-situ pH measurement tasks in deep-sea environments.

[0004] However, the deep-sea environment places high demands on the corrosion resistance and pressure resistance of detection devices, making it difficult for optical pH sensor probes to operate for extended periods in the deep sea. Therefore, designing a deep-sea optical pH sensor that is simple in structure, easy to fabricate, and highly pressure-resistant is an important research topic. Summary of the Invention

[0005] In view of this, the present invention provides an optical sensing and detection device for pH in deep-sea environments.

[0006] One aspect of the present invention provides an optical sensing and detection device for pH in a deep-sea environment, comprising: a pressure-resistant housing; a front end cover fixed to a first side; a tapered hole on the front end cover; a sapphire pH detection component fixed within the tapered hole; the sapphire pH detection component includes a sapphire optical window and a pH-sensitive membrane covalently bonded to the side of the sapphire optical window facing the seawater; an optical component and a detection component are fixed within a sealed cavity formed by the pressure-resistant housing and the front end cover; the optical component generates excitation light and transmits the excitation light to the sapphire pH detection component to excite the pH-sensitive membrane to generate detection light, the intensity of which is related to the pH of the seawater; the detection component receives detection light, excitation light, and deep-sea ambient light from the sapphire pH detection component to generate a detection signal; a transmission interface is provided on a second side of the pressure-resistant housing opposite to the front end cover, electrically connected to the detection component, to transmit the detection signal through the transmission interface.

[0007] According to an embodiment of the present invention, the angle of the conical hole and the size of the conical hole are in a preset matching relationship, so that the peak pressure inside the conical hole is the minimum pressure among multiple matching relationships; the preset matching relationship includes: the ratio of the depth of the conical hole along the height direction to the radius of the bottom circle of the conical hole is 1, and the angle of the conical hole is between 40° and 50°.

[0008] According to an embodiment of the present invention, the sapphire-pH detection component further includes a copper mesh, which is disposed on the side of the pH sensitive membrane away from the sapphire light window. The bottom circular of the conical hole is opposite to the copper mesh. A preset matching relationship causes seawater to generate a vortex zone between the conical hole and the copper mesh, forming a backflow vortex attached to the front of the sapphire light window, so as to clean the seawater attachment on the copper mesh through the backflow vortex.

[0009] According to an embodiment of the present invention, the surface of the sapphire window is modified with hydroxyl groups; the pH-sensitive film includes a pH-sensitive dye and a linking segment, one end of the linking segment is bonded to the hydroxyl group of the sapphire window through a silicon-oxygen bond, and the other end is bonded to the pH-sensitive dye through an amide bond; the excitation light emitted by the pH-sensitive dye is in the visible light band.

[0010] According to embodiments of the present invention, the acid-base sensitive dye includes at least one of the following: quantum dots, photoinduced electron transfer dyes, or conventional dyes.

[0011] According to an embodiment of the present invention, when the acid-base sensitive dye is a carboxylated water-soluble quantum dot, the linking segment is formed by amidation of the carboxyl group of the acid-base sensitive dye with a silane coupling agent having an amino group at the end, and silanization of the hydroxyl group of the sapphire window.

[0012] According to an embodiment of the present invention, the optical component includes: a light source module for generating excitation light through an electrical signal provided by a transmission interface; the wavelength of the excitation light generated by the light source module corresponds to the pH-sensitive film; and a first focusing lens for focusing the excitation light and transmitting the focused excitation light to the sapphire-pH detection component.

[0013] According to an embodiment of the present invention, the detection component includes: a filter for receiving detection light, excitation light and deep-sea ambient light from the sapphire-pH detection component, and filtering out the deep-sea ambient light and excitation light; a second focusing lens for receiving detection light from the filter and focusing the detection light onto a photodetector; and a photodetector for converting the detection light into a detection signal.

[0014] According to an embodiment of the present invention, the pressure-resistant housing is made of titanium alloy.

[0015] Another aspect of the present invention provides an optical sensing and detection system for pH in a deep-sea environment, comprising: an optical sensing and detection device for pH in a deep-sea environment; and a cable electrically connected to the transmission interface of the optical sensing and detection device for pH in a deep-sea environment, so as to provide an electrical signal to the optical sensing and detection device for pH in a deep-sea environment and / or transmit an in-situ detection signal through the cable.

[0016] According to an embodiment of the present invention, the system can withstand a pressure range of 0 to 60 MPa and can detect water depths of 0 to 6000 m.

[0017] This invention employs a pressure-resistant housing and an integrated sapphire-alkalinity detection component, eliminating the interface gaps and weak sealing points present in traditional split structures. This not only withstands the continuous pressure of the deep sea, preventing signal drift or interface peeling caused by pressure fluctuations, but also ensures the structural integrity of the sensing device under high pressure, thereby guaranteeing high measurement accuracy. Furthermore, the acid-alkalinity sensitive membrane is legally fixed to the sapphire surface via covalent bonds. Covalent bonds, as strong interactions formed between atoms through electron pair sharing, have bond energies far exceeding those of physical adsorption such as van der Waals forces. This results in a stable integrated structure between the acid-alkalinity sensitive membrane and the sapphire window, preventing leakage of the acid-alkalinity dye and enabling continuous, stable, and reliable acid-alkalinity monitoring in deep-sea environments. Attached Figure Description

[0018] The above and other objects, features and advantages of the present invention will become clearer from the following description of embodiments of the invention with reference to the accompanying drawings.

[0019] Figure 1 A structural diagram of an optical sensing device for detecting the acidity and alkalinity of a deep-sea environment according to an embodiment of the present invention is shown.

[0020] Figure 2 A schematic diagram illustrating the preparation process of a carboxyl-based water-soluble quantum dot pH-sensitive membrane for a deep-sea environment pH optical sensing and detection device according to an embodiment of the present invention is shown.

[0021] Figure 3 A schematic diagram and a physical image of a sapphire pH detection component for a deep-sea environment pH optical sensing device according to an embodiment of the present invention are shown.

[0022] Figure 4 A schematic diagram of the grid division of an optical sensing and detection device for pH in a deep-sea environment according to an embodiment of the present invention is shown.

[0023] Figure 5A A simulated pressure cloud map of a cross-section of an optical sensing device for pH in a deep-sea environment, according to an embodiment of the present invention, is shown.

[0024] Figure 5B A simulated velocity vector diagram of an optical sensing device for detecting pH in a deep-sea environment, according to an embodiment of the present invention, is shown.

[0025] Figure 6 An optical sensing device for detecting the acidity and alkalinity of a deep-sea environment is shown according to a specific embodiment of the present invention.

[0026] Figure 7 A schematic diagram of the experimental spectrum of an optical sensing device for pH in a deep-sea environment according to an embodiment of the present invention is shown.

[0027] Figure 8 A sensitivity trend graph of an optical sensing device for pH in a deep-sea environment according to an embodiment of the present invention is shown. Detailed Implementation

[0028] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the invention. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the invention for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0029] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0030] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0031] When using expressions such as "at least one of A, B and C", they should generally be interpreted in accordance with the meaning that is commonly understood by those skilled in the art (e.g., "a system having at least one of A, B and C" should include, but is not limited to, a system having A alone, a system having B alone, a system having C alone, a system having A and B, a system having A and C, a system having B and C, and / or a system having A, B and C, etc.).

[0032] Significant progress has been made in the field of optical pH sensors. Optical pH sensing principles include fluorescence emission and surface plasmon resonance, but none of them involve the design of pressure resistance of optical sensing probes. Therefore, their structural strength and sealing performance cannot be adapted to the high-pressure environment of the deep sea, making it difficult to achieve long-term stable operation. Therefore, there is an urgent need for a pressure-resistant pH detection device adapted to deep-sea scenarios.

[0033] Figure 1 A structural diagram of an optical sensing device for detecting acidity and alkalinity in a deep-sea environment, according to an embodiment of the present invention, is shown. Figure 1 As shown, the device includes: a pressure-resistant housing 10, a front end cover 60 fixed on the first side, the front end cover 60 having a conical hole, and a sapphire pH detection component 20 fixed inside the conical hole. The sapphire pH detection component 20 includes a sapphire optical window and a pH-sensitive membrane fixed to the sapphire optical window facing the seawater contact side by covalent bonding. An optical component 30 and a detection component 40 are fixed inside a sealed cavity formed by the pressure-resistant housing 10 and the front end cover 60. The optical component 30 is used to generate excitation light and transmit the excitation light to the sapphire pH detection component 20 to excite the pH-sensitive membrane to generate detection light. The intensity of the detection light is related to the pH of the seawater. The detection component 40 is used to receive detection light, excitation light, and deep-sea ambient light from the sapphire pH detection component 20 to generate a detection signal. A transmission interface 50 is provided on the second side of the pressure-resistant housing 10 opposite to the front end cover 60, which is electrically connected to the detection component 40 to transmit the detection signal through the transmission interface 50.

[0034] In practical applications such as deep-sea exploration and underwater equipment maintenance, the pressure generated by seawater can reach tens or even hundreds of times that of atmospheric pressure as the exploration depth increases. This extreme pressure environment poses a severe challenge to the structural integrity, sealing performance, and normal operation of core sensing components of the device. To ensure the long-term stable operation of the sensing and monitoring device under complex deep-sea conditions and to prevent shell deformation, seal failure, or damage to internal circuits and sensitive components due to pressure loads, thereby ensuring the accuracy and reliability of the detection data, this invention first provides a pressure-resistant shell 10 to ensure that the device can effectively withstand the high-pressure loads of the deep sea and continuously perform accurate acid and alkalinity detection. Through the synergistic effect of reasonable structural design and material properties, the pressure-resistant shell 10 can balance external pressure loads and disperse stress, avoiding structural deformation and thus ensuring the integrity and effectiveness of the internal core components.

[0035] The front end cap 60 on the first side of the pressure-resistant housing 10 has a conical hole, within which a sapphire pH detection component 20 is fixed. The sapphire pH detection component 20 includes a sapphire optical window and a pH-sensitive membrane. The sapphire optical window, with its extremely high mechanical strength and pressure resistance, completely physically isolates the internal electronic and optical components from the external high-pressure seawater, serving as the core pressure-bearing and sealing structure that ensures the device can operate in deep sea conditions. Simultaneously, the sapphire optical window possesses high light transmittance across an extremely wide wavelength range from ultraviolet to infrared, allowing efficient transmission of 470nm excitation light and emitted fluorescence, while itself generating almost no fluorescence, ensuring an extremely high signal-to-noise ratio.

[0036] Traditional split-type pH-sensitive membranes, which are fixed by physical adsorption based on van der Waals forces, hydrogen bonds, or electrostatic interactions—all weak interactions—are easily detached by water currents under the high pressure of the deep sea, making long-term in-situ measurements in deep-sea environments difficult. Therefore, this invention uses a covalent bonding method to prepare a uniformly thick pH-sensitive membrane on a sapphire optical window, ensuring a strong bond between the membrane and the window. Since covalent bonds have higher energy than weakly interacting bonds, the pH-sensitive membrane prepared using this method can withstand the high-pressure cycling of the deep-sea environment, preventing leakage of the pH-sensitive dye.

[0037] To detect the fluorescence of the pH-sensitive membrane, an optical component 30 and a detection component 40 are fixed within a sealed cavity formed by the pressure-resistant housing 10 and the front cover 60. The core function of the optical component 30 is to construct a stable signal transmission system. Through the generated excitation light, it excites the pH-sensitive membrane to produce fluorescence of varying degrees based on the pH of the seawater; this fluorescence can then be used as the detection light. It should be noted that for the pH-sensitive membrane in the integrated sapphire-pH detection component 20, when the hydrogen ions (H+) in the seawater... +When the concentration changes, the chemical state of the pH-sensitive dye on the pH-sensitive membrane changes, resulting in a corresponding change in fluorescence intensity, thus enabling subsequent seawater pH measurement. The detection component 40 is used to capture and convert the detection light, transforming the optically interacted detection light into a detection signal. To facilitate the transmission of the detection signal, a transmission interface 50 is provided on the second side of the pressure-resistant housing 10 opposite to the front cover 60, allowing external devices to be electrically connected to the detection component 40 via the transmission interface 50.

[0038] This invention employs a pressure-resistant housing and an integrated sapphire-alkalinity detection component, eliminating the interface gaps and weak sealing points present in traditional split structures. This not only withstands the continuous pressure of the deep sea, preventing signal drift or interface peeling caused by pressure fluctuations, but also ensures the device maintains structural integrity under deep-sea pressure, thus maintaining high measurement accuracy. Furthermore, the sensitive membrane is legally fixed to the sapphire surface via covalent bonds, making it leak-proof and enabling continuous, stable, and reliable acid-alkalinity detection in deep-sea environments.

[0039] According to an embodiment of the present invention, the pressure-resistant shell 10 is made of titanium alloy. Titanium alloy has a stable structure and its surface easily forms a dense and firmly bonded oxide film, thus exhibiting excellent corrosion resistance and maintaining the structural integrity of the shell for a long time. Titanium alloy combines high strength and high toughness, which can resist plastic deformation under deep-sea high pressure and effectively disperse stress concentration, preventing shell rupture.

[0040] According to an embodiment of the present invention, the surface of the sapphire window is modified with hydroxyl groups; the pH-sensitive film includes a pH-sensitive dye and a linking segment, one end of the linking segment is bonded to the hydroxyl group of the sapphire window through a silicon-oxygen bond, and the other end is bonded to the pH-sensitive dye through an amide bond.

[0041] The excitation light emitted by acid-base sensitive dyes is in the visible light band, meaning that the fluorescence of acid-base sensitive dyes is in the visible light band.

[0042] Acidity-base sensitive dyes include at least one of the following: quantum dots, photoinduced electron transfer dyes, or conventional dyes. For example, quantum dot-type acidity-base sensitive dyes may include carboxylated water-soluble quantum dots, and photoinduced electron transfer dyes may include 4-amino-1,8-naphthylimine-ethyl-2,6-dichlorophenol. Specifically, the excitation wavelength of the carboxylated water-soluble quantum dots is 575 nm, and the excitation wavelength of the 4-amino-1,8-naphthylimine-ethyl-2,6-dichlorophenol is 522.6 nm.

[0043] According to an embodiment of the present invention, when the acid-base sensitive dye is a carboxylated water-soluble quantum dot, the linking segment is formed by amidation of the carboxyl group of the acid-base sensitive dye with a silane coupling agent having an amino group at the end, and silanization of the hydroxyl group of the sapphire window.

[0044] Figure 2 A schematic diagram illustrating the preparation process of a carboxyl-based water-soluble quantum dot pH-sensitive membrane for a deep-sea environment pH optical sensing device according to an embodiment of the present invention is shown. Figure 2 As shown, taking the preparation of a carboxyl water-soluble quantum dot pH-sensitive membrane as an example, the pH-sensitive membrane uses water-soluble quantum dots as pH-sensitive dyes and is rich in carboxyl groups that can be used for covalent bonding on its surface. The covalent bonding method mainly includes the following process steps.

[0045] Hydroxylation: The surface of the sapphire window is treated with oxygen plasma to introduce a large number of hydroxyl groups (–OH) into the surface, while removing organic contaminants.

[0046] Silanization: The hydroxylated substrate is immersed in an APTES (3-aminopropyltriethoxysilane) solution and reacted for 2 hours. The ethoxy groups of APTES undergo a condensation reaction with the surface hydroxyl groups to form Si–O–Al covalent bonds, thereby introducing amino groups onto the surface.

[0047] Amide formation: EDC (1-ethyl-3-(3-dimethylaminopropyl)carbodiimide) and NHS (N-hydroxysuccinimide) are added as catalysts. The surface amino groups react with the activated carboxyl groups to form stable amide bonds (–CO–NH–). The reaction time is about 4 hours.

[0048] It should be noted that amide bonds (–CO–NH–) and silicon-oxygen bonds (Si–O–Al) are saturated σ bonds with energies much higher than the excited state energy levels of carboxyl water-soluble quantum dots. They do not participate in the photoelectron transition process. Furthermore, covalent bonding is an end modification that does not affect the core structure of the quantum dot's photophysical activity. The energy level matching mechanism of the hydrogen ion response is completely preserved. Therefore, the covalent bonding method of film formation will not affect the detection mechanism of the acid-base sensitive film.

[0049] It is understandable that for other photoinduced electron transfer dyes such as 4-amino-1,8-naphthimine-ethyl-2,6-dichlorophenol, or other traditional dyes, the corresponding linker segments can be selected and legally fixed to the surface of the sapphire window through covalent bonds, thereby ensuring that the acid-base sensitive film and the sapphire window are tightly fixed by strong chemical bonds.

[0050] Covalent bonds, as strong interactions formed between atoms through the sharing of electron pairs, possess a bond energy that is orders of magnitude greater than that of van der Waals forces and electrostatic adsorption. This allows the pH-sensitive membrane and the sapphire window to be tightly integrated into a stable, unified structure, rather than simply being physically attached. This effectively confines pH dye molecules, preventing their desorption and dissolution from the membrane matrix during high-pressure immersion in the deep sea, fluid scouring, or long-term operation. It fundamentally avoids the dye leakage problem caused by weak interfacial bonding in physical adsorption methods, ensuring the long-term stability of the membrane's fluorescence response performance and providing a guarantee for pH detection in deep-sea environments.

[0051] Figure 3 A schematic diagram and physical image of a sapphire-acidity detection component for a deep-sea environment acidity / alkalinity optical sensing device according to an embodiment of the present invention are shown. Figure 3 As shown, this is a sapphire pH detection component obtained based on the above operations.

[0052] The sapphire optical window and the pH-sensitive membrane are tightly bonded by covalent bonds. This not only avoids the scattering of the probe light and energy loss caused by seawater and air bubbles in the gap, ensuring the efficient and stable transmission of excitation and probe light, but also blocks the intrusion of high pressure, corrosive media and microorganisms in the deep sea, preventing the sensitive membrane from falling off, swelling and contaminating the optical window. This improves the device's response speed and anti-interference ability, making it more suitable for the high-precision, long-cycle, real-time pH monitoring needs in the extreme environment of the deep sea.

[0053] According to an embodiment of the present invention, the angle of the conical hole and the size of the conical hole are in a preset matching relationship so as to minimize the peak pressure inside the conical hole; the preset matching relationship includes: the ratio of the depth of the conical hole along the height direction to the radius of the bottom circle of the conical hole is 1, and the angle of the conical hole is between 40° and 50°.

[0054] To ensure free flow of seawater, prevent seawater deposits from remaining inside the front cover, and reduce the frontal impact pressure of seawater on the front cover, computational fluid dynamics simulation was used to establish the matching relationship between the angle α of the conical hole, the depth of the conical hole, and the ratio β of the top circle radius of the conical hole facing the sapphire. The optimal α and β were then selected to achieve the above effects.

[0055] Figure 4 A schematic diagram of the grid division for an optical sensing and detection device for pH in a deep-sea environment, according to an embodiment of the present invention, is shown. Figure 4 As shown, a model of an optical pH sensing and monitoring device with a conical orifice design was established using simulation software, and the model was meshed. The model was imported into the simulation module, and the initial seawater flow velocity was set to 1 m / s to simulate and calculate the pressure distribution across the sensing chamber profile. The simulation results show the relationship between the maximum pressure F inside the conical orifice and α and β, as shown in Table 1.

[0056] Table 1

[0057]

[0058] To reduce the impact pressure of seawater on the front end cover, preferably, the front end cover has a conical hole with an angle of α=45° and a structural parameter of β=1, where the depth of the conical hole along the height direction is β=1.

[0059] According to an embodiment of the present invention, the sapphire pH detection component further includes a copper mesh disposed on the side of the pH sensitive film away from the sapphire light window.

[0060] To ensure the device's corrosion resistance, a copper mesh is precision laser-cut into a microporous array on a thin sheet and then laser-welded to the outermost side of the pressure-resistant housing 10, serving as the first physical barrier. The mounting interface is designed with grooves and embedded O-rings to ensure a good seal between the copper mesh pressure ring and the pressure-resistant housing 10, preventing seawater from seeping into the device through side gaps. In marine environments, microorganisms, algae, barnacles, and other organisms can adhere to the device surface, forming a biofilm. This severely hinders the contact between seawater and the sensing membrane, contaminates the optical window, and leads to measurement signal drift and eventual failure. The copper mesh can slowly release copper ions. As a transition metal ion, copper ions possess both strong redox properties and coordination binding ability. They can disrupt the permeability of microbial cell membranes, bind to the active sites of enzymes and inhibit key enzyme functions, blocking energy metabolism and genetic material replication. They can also catalyze the production of reactive oxygen species that damage biomolecules, ultimately inhibiting microbial growth and reproduction or causing their death, thus effectively preventing organisms from attaching and growing on its surface.

[0061] According to an embodiment of the present invention, the bottom circular portion of the conical aperture faces away from the copper mesh. Under the aforementioned preset matching relationship, the peak pressure inside the conical aperture is the minimum pressure among multiple matching relationships. Furthermore, guided by the conical aperture, seawater generates a vortex zone between the conical aperture and the copper mesh, forming a backflow vortex attached to the front of the sapphire optical window. This backflow vortex cleans the seawater deposits on the copper mesh. This backflow vortex is a pressurized liquid flow with a certain velocity, acting on the inner surface of the sapphire optical window to wash away any microorganisms, sediments, seawater salt, and other contaminants that may be attached to the surface of the sapphire optical window. This prevents the accumulation of contaminants from causing a decrease in the light transmittance of the optical window, thereby ensuring the stability and integrity of the signals transmitted by the optical components and ensuring that the device maintains accurate detection performance during long-term deep-sea operation.

[0062] Figure 5A A simulated pressure cloud map of a cross-section of an optical sensing device for pH in a deep-sea environment, according to an embodiment of the present invention, is shown. Figure 5A As shown, the maximum frontal impact pressure exerted by seawater on the front end cap is 2.67 × 10⁻⁶. 3 Pa. Figure 5B A simulated velocity vector diagram of an optical sensing device for pH detection in a deep-sea environment, according to an embodiment of the present invention, is shown. Figure 5B As shown in the velocity vector diagram, the fluid flows around the conical head, forming a distinct, closed vortex streamline. All seawater flows in and out, leaving no residue inside the conical orifice. The stable vortex zone generated at the device head enables non-contact active cleaning of the optical window, ensuring that ions released from the anti-biofouling copper mesh effectively cover the sensing interface. Simultaneously, the conical orifice transforms the incoming high-speed seawater into low-speed seawater, demonstrating its buffering effect on the seawater.

[0063] By rationally designing the angle and size of the conical aperture, pollutants such as marine microorganisms, sediments, and salt deposits attached to the surface of the sapphire window can be removed in a timely manner. This avoids the degradation of the light transmission performance of the window caused by biofilm formation and impurity accumulation, ensuring efficient transmission of excitation and detection light, maintaining the detection sensitivity and measurement accuracy of the device, and reducing the impact pressure of seawater on the device. This provides key support for the accurate and continuous monitoring of deep-sea pH values.

[0064] According to an embodiment of the present invention, the optical component includes: a light source module for generating excitation light through an electrical signal provided by a transmission interface, wherein the wavelength of the excitation light generated by the light source module corresponds to the pH-sensitive film; and a first focusing lens for focusing the excitation light and transmitting the focused excitation light to the sapphire-pH detection component.

[0065] The light source can be selected according to the absorption band of different acid-base sensitive membranes (that is, the absorption band of acid-base sensitive fuel in acid-base sensitive membranes). For example, the light source is generally a light source in the ultraviolet to visible band, such as a 405nm or 470nm laser.

[0066] In one specific embodiment, the light source can be a 470nm laser diode (LD) light source, which has the characteristics of good monochromaticity and stable light intensity.

[0067] The first focusing lens is located behind the light source, which focuses the excitation light emitted by the light source into a more concentrated and collimated beam to improve the efficiency and intensity of the excitation light reaching the sapphire pH detection component, thereby enhancing the sensitivity and stability of the entire device system for detecting pH values ​​in the deep-sea environment.

[0068] According to an embodiment of the present invention, the detection component includes: a filter for receiving detection light, excitation light and deep-sea ambient light from the sapphire-pH detection component, and filtering out the deep-sea ambient light and excitation light; a second focusing lens for receiving detection light from the filter and focusing the detection light onto a photodetector; and a photodetector for converting the detection light into a detection signal.

[0069] The second focusing lens, located in the return optical path, is used to maximize the collection of fluorescence and reflected excitation light generated from the sapphire-pH detection component 20 and efficiently converge it onto the photosensitive surface of the photodetector. A filter is positioned in front of the photodetector, allowing only the detection light generated by the pH-sensitive film to pass through, while strongly blocking reflected excitation light and deep-sea ambient light. This is one of the key components for improving the detection signal-to-noise ratio and ensuring measurement accuracy. The photodetector converts the detection light into a detection signal, detects and receives the detection light returned from the sapphire-pH detection component 20, and proportionally converts its intensity into a weak detection signal (current or voltage signal).

[0070] According to an embodiment of the present invention, the system further includes: a cable electrically connected to the transmission interface of the optical sensing and detection device for pH in the deep-sea environment, so as to transmit electrical signals of the optical sensing and detection device for pH in the deep-sea environment and / or in-situ detection signals via the cable.

[0071] In this invention, the cable serves as a core connecting component, providing bidirectional functional support: on the one hand, it accurately transmits the stable electrical signal output by the external drive unit to the device's light source, providing reliable energy for the light source; on the other hand, the cable simultaneously transmits the detection signal outward, transmitting the electrical signal captured and converted by the device's detection components to the external data processing unit, providing high-quality signal support for subsequent data analysis and application, ultimately achieving bidirectional coordination of energy input and signal output, ensuring the smooth operation of the overall detection process of the device.

[0072] According to embodiments of this disclosure, the pH optical sensing detection system constructed using the above-described device possesses deep-sea pressure resistance (pressure-resistant design such as titanium alloy shell and integrated sapphire pH detection component), eliminating the interface gaps and weak sealing links present in traditional split structures. This enables the pH optical sensing detection system to withstand the continuous action of 6000-meter deep-sea high pressure (0 ~ 60 MPa), preventing signal drift or interface peeling caused by pressure fluctuations, and further ensuring that the sensor maintains structural integrity and measurement accuracy under 6000m deep-sea high pressure.

[0073] Figure 6 An optical sensing device for detecting pH in a deep-sea environment is shown according to a specific embodiment of the present invention. For example... Figure 6As shown, the pressure-resistant housing 10 provides the entire device with comprehensive high-pressure bearing capacity, ensuring structural integrity and sealing reliability under extreme deep-sea pressure environments, and creating a stable working space for internal optical and detection components. The copper mesh 23 at the front cover utilizes the chemical properties of copper ions to effectively inhibit the attachment and growth of marine microorganisms, preventing the formation of biofilms on sensitive components and thus preventing the attenuation of optical sensitivity due to biological contamination, ensuring the stability of long-term deep-sea detection. When seawater comes into contact with the pH-sensitive membrane 22 fixed on the sapphire window 21, the pH-sensitive membrane 22 changes its properties due to differences in seawater pH. At this time, the excitation light emitted by the light source 32 acts on the pH-sensitive membrane 22, causing it to generate pH-related detection light. The first focusing lens 31 optically focuses the emitted detection light, enhancing its concentration and intensity. In the receiving optical path, the filter 41 filters out interference signals, ensuring that only pH-related detection light passes through. The filtered detection light is focused by the second focusing lens 42 and efficiently transmitted to the photodetector 43. The photodetector 43 converts the detection light into a quantifiable detection signal. Subsequent signal processing enables precise measurement and output of the pH value of the deep-sea environment, providing reliable data support for deep-sea chemical environment monitoring. The transmission interface 50 is used to transmit the detection signal.

[0074] According to an embodiment of the present invention, taking the photoinduced electron transfer dye 4-amino-1,8-naphthimine-ethyl-2,6-dichlorophenol as an example, the steps for measuring acidity and alkalinity using the device of the present invention include:

[0075] Setting up the sensing system: The sapphire window was ground and polished to make its surface smooth and flat. The end face was cleaned with alcohol and purified water. The photoinduced electron transfer dye 4-amino-1,8-naphthimine-ethyl-2,6-dichlorophenol was embedded in ethyl cellulose and hydrogel and centrifuged until homogeneous. A composite sensing material was spin-coated onto the surface of the sapphire window and allowed to dry and form a film. A small hole was made in the center of a metal disk, and the uncoated side of the sapphire window was attached to the metal disk. The other side of the metal disk was connected to the cable. The surface of the sensing device was wiped clean with alcohol, and the sensing system was assembled. An LD light source with a center wavelength of 470 nm was used as the excitation source. The emitted probe light was received by a spectrometer, and the spectral data was finally saved and processed by computer software.

[0076] It should be noted that the pH optical sensing detection device uses the photoinduced electron transfer dye 4-amino-1,8-naphthylimine-ethyl-2,6-dichlorophenol as the pH-sensitive dye. This pH-sensitive dye is composed of a fluorescent group (4-amino-1,8-naphthylimine), a spacer group (ethyl), and an acceptor (2,6-dichlorophenol). The fluorescent group is responsible for absorbing light energy and emitting probe light. The spacer group separates the fluorescent group and the acceptor, and also connects them into a single molecule. The acceptor, also known as the recognition group, can bind to the analyte. When the acceptor is not bound to the analyte, light irradiation excites the fluorescent group, and correspondingly, an electron transitions from the Highest Occupied Molecular Orbital (HOMO) level to the Lowest Unoccupied Molecular Orbital (LUMO) level. At this point, the HOMO level of the acceptor lies between the HOMO and LUMO levels of the fluorophore. Electrons in the HOMO level of the acceptor will transition to the HOMO level of the fluorophore, transferring electrons to the vacated HOMO level. Although the LUMO level of the fluorophore receives electrons from the HOMO level, there are no electrons that can transition back to the HOMO level; that is, excited-state electrons cannot return to the ground state. Therefore, no fluorescence is produced, and fluorescence quenching occurs. When the acceptor binds to the analyte, the HOMO level of the acceptor is lower than that of the fluorophore, so there is no electron donation and acceptance relationship between the fluorophore and the acceptor. In this case, electrons in the LUMO level of the fluorophore relax and can transition back to the HOMO level, resulting in fluorescence emission.

[0077] A certain volume of pH buffer solution was placed in a beaker, immersing the sensor probe in it, and the changes in the fluorescence spectrum of the spectrometer were observed sequentially. Figure 7 A schematic diagram of the experimental spectrum of an optical sensing device for pH in a deep-sea environment according to an embodiment of the present invention is shown. Figure 7 As shown, the device detects light intensity spectra in solutions with pH values ​​of 7.0, 7.5, 8.0, 8.5, and 9.0. After excitation by an LD light source, the sensitive membrane in the water exhibits different spectral responses at different hydrogen ion concentrations. Based on this core characteristic, the optical detection system accurately captures the detection light intensity of the pH-sensitive membrane at a specific wavelength. The unit of detection light intensity is the Augmentation Unit (au). Combined with a preset detection light intensity-pH calibration model, the pH value of the target water body can be derived in reverse, thus achieving efficient and accurate detection of pH parameters.

[0078] Figure 8 A sensitivity trend graph of an optical sensing device for pH in a deep-sea environment, according to an embodiment of the present invention, is shown. Figure 8 As shown, the probe light intensity and fitting curves are presented in solutions with pH values ​​of 7.0, 7.5, 8.0, 8.5, and 9.0. The unit of probe light intensity is Augmentation Unit (au). The results show a linear relationship between pH and probe light intensity, further demonstrating that pH can be accurately measured using probe light intensity. Experimental verification showed that the device remained intact after immersion in a pH 8 buffer solution for 30 consecutive days, providing a reliable technical approach for long-term monitoring of pH values ​​in the deep sea.

[0079] This invention employs a pressure-resistant housing and an integrated sapphire-pH detection component, eliminating the interface gaps and weak sealing points present in traditional split structures. This not only withstands the continuous pressure of the deep sea, preventing signal drift or interface peeling caused by pressure fluctuations, but also ensures the device maintains structural integrity under deep-sea pressure, thereby guaranteeing high measurement accuracy. Furthermore, the sensitive membrane is legally fixed to the sapphire surface via covalent bonds, making it leak-proof and enabling continuous, stable, and reliable pH monitoring in deep-sea environments.

[0080] The embodiments of the present invention have been described above. However, these embodiments are merely illustrative and not intended to limit the scope of the invention. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of the invention, and all such substitutions and modifications should fall within the scope of the invention.

Claims

1. A pH optical sensing and detection device for deep-sea environments, characterized in that, The device includes: A pressure-resistant housing has a front cover fixed on the first side. The front cover has a conical hole, and a sapphire pH detection component is fixed inside the conical hole. The sapphire pH detection component includes a sapphire window and a pH-sensitive membrane that is covalently bonded to the side of the sapphire window facing the seawater. Optical components and detection components are fixed inside the sealed cavity formed by the pressure-resistant housing and the front end cover; The optical component is used to generate excitation light and transmit the excitation light to the sapphire-pH detection component to excite the pH-sensitive membrane to generate detection light, the intensity of which is related to the pH of seawater; the detection component is used to receive the detection light, excitation light and deep-sea ambient light from the sapphire-pH detection component to generate a detection signal. The pressure-resistant housing is provided with a transmission interface on the second side opposite to the front end cover, which is electrically connected to the detection component to transmit the detection signal through the transmission interface; The angle of the tapered orifice and the size of the tapered orifice are in a preset matching relationship so that the peak pressure inside the tapered orifice is the minimum pressure among multiple matching relationships; The preset matching relationship includes: the ratio of the depth of the conical hole along the height direction to the radius of the bottom circle of the conical hole is 1, and the angle of the conical hole is between 40° and 50°; The sapphire pH detection component also includes a copper mesh, which is disposed on the side of the pH sensitive film away from the sapphire light window; The bottom circle of the conical hole is opposite to the copper mesh. The preset matching relationship causes the seawater to generate a vortex zone between the conical hole and the copper mesh, forming a backflow vortex attached to the front of the sapphire window, so as to clean the seawater deposits on the copper mesh through the backflow vortex.

2. The apparatus according to claim 1, characterized in that, The surface of the sapphire window is modified with hydroxyl groups; The pH-sensitive membrane includes a pH-sensitive dye and a linker segment. One end of the linker segment is connected to the hydroxyl group of the sapphire window via a silicon-oxygen bond, and the other end is connected to the pH-sensitive dye via an amide bond. The wavelength of the excitation light emitted by the acid-base sensitive dye is in the visible light band.

3. The apparatus according to claim 2, characterized in that, The pH-sensitive dye includes at least one of the following: quantum dots, photoinduced electron transfer dyes, or conventional dyes.

4. The apparatus according to claim 3, characterized in that, In the case where the pH-sensitive dye is a carboxylated water-soluble quantum dot, the linking segment is formed by amidation of the carboxyl group of the pH-sensitive dye with a silane coupling agent having an amino group at the end, and silanization of the hydroxyl group of the sapphire window.

5. The apparatus according to claim 1, characterized in that, The optical components include: A light source module is used to generate the excitation light through an electrical signal provided by the transmission interface, wherein the wavelength of the excitation light generated by the light source module corresponds to the pH-sensitive membrane. The first focusing lens is used to focus the excitation light and transmit the focused excitation light to the sapphire-pH detection component. The detection component includes: A filter is used to receive the detection light, the excitation light, and the deep-sea ambient light from the sapphire-pH detection component, and to filter out the deep-sea ambient light and the excitation light; The second focusing lens is used to receive the probe light from the filter and converge the probe light to the photodetector; A photodetector is used to convert the detection light into the detection signal.

6. The apparatus according to claim 1, characterized in that, The pressure-resistant shell is made of titanium alloy.

7. A deep-sea environment pH optical sensing and detection system, characterized in that, The system includes: The optical sensing and detection device for acidity and alkalinity in deep-sea environments as described in any one of claims 1 to 6; The cable is electrically connected to the transmission interface of the optical sensing device for pH in the deep-sea environment, so as to provide electrical signals to the optical sensing device for pH in the deep-sea environment and / or transmit in-situ detection signals through the cable.

8. The system according to claim 7, characterized in that, The system can withstand pressures ranging from 0 to 60 MPa and can detect water depths ranging from 0 to 6000 m.

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