Flexible hydrogen leakage sensing patch, preparation method thereof and hydrogen leakage monitoring system

Abstract

The application discloses a flexible hydrogen leakage sensing patch, a preparation method thereof and a hydrogen leakage monitoring system. The patch comprises a flexible substrate, a functional layer, an electrode layer and a packaging layer. The functional layer comprises a conductive metal film layer arranged on the top surface of the flexible substrate and a nanowire array arranged on the top surface of the conductive metal film layer. The functional layer is peeled off from a rigid substrate and transferred to the flexible substrate. The electrode layer is arranged on the top surface of the nanowire array and used for forming an electrical signal lead-out end. The packaging layer covers the electrode layer and the nanowire array, and a hydrogen permeation window for passing hydrogen into the nanowire array is arranged on the packaging layer. The hydrogen leakage sensing patch is based on the flexible substrate, can be directly attached to a complex curved surface, has excellent conformal fitting characteristics, and the functional layer of the application is peeled off from the rigid substrate and transferred to the flexible substrate. The transfer process avoids the problems caused by the fact that the flexible substrate cannot adapt to high temperature and the surface roughness of the flexible substrate, and guarantees the high quality and consistency of the nanowire array.

Description

Technical Field

[0001] This invention relates to a flexible hydrogen leak sensing patch and its preparation method, as well as a hydrogen leak monitoring system, belonging to the field of hydrogen energy safety monitoring and gas sensing technology. Background Technology

[0002] With the rapid development of the hydrogen energy industry, the application of hydrogen fuel cell vehicles, high-pressure hydrogen storage tanks, and hydrogen transportation pipelines is becoming increasingly widespread. Due to the characteristics of hydrogen—colorless and odorless, rapid diffusion, wide explosion limits (4%-75%), and low ignition energy—leaks can easily lead to safety accidents. Therefore, monitoring hydrogen leaks at key points of hydrogen storage facilities is a prerequisite for ensuring the safety of hydrogen energy applications.

[0003] Currently, there are two main types of hydrogen sensors: one type is based on rigid structures such as ceramic tubes or silicon wafers. These sensors are difficult to fit tightly into complex curved structures such as high-pressure hydrogen storage cylinders, pipeline valves, and joints, and cannot meet the requirements for conformal fitting monitoring. The other type is based on flexible substrates. In the fabrication of these sensors, high-performance metal oxide nanomaterials usually require high-temperature environments (>400℃) to ensure good crystallinity and gas-sensing performance. However, flexible substrates are not heat-resistant (easily carbonized) and have rough surfaces, making it difficult to directly grow a uniformly oriented, highly ordered array structure on their surface. Therefore, existing flexible sensors mostly use disordered nanonetworks as the gas-sensing layer. When subjected to mechanical deformation such as bending, the contact points between materials are prone to breakage or slippage, causing strong resistance drift. This drift can easily mask the response of trace amounts of hydrogen, thus producing false positives. Summary of the Invention

[0004] This invention provides a flexible hydrogen leak sensing patch and its preparation method, as well as a hydrogen leak monitoring system, which solves the problems disclosed in the background art.

[0005] According to one aspect of this application, a flexible hydrogen leak sensing patch is provided, comprising:

[0006] Flexible substrate;

[0007] The functional layer includes a conductive metal thin film layer disposed on the top surface of a flexible substrate and a nanowire array disposed on the top surface of the conductive metal thin film layer; the functional layer is peeled off from the rigid substrate and transferred to the flexible substrate; wherein, the nanowires in the nanowire array have resistive response characteristics to hydrogen gas.

[0008] An electrode layer, disposed on the top surface of the nanowire array, is used to form electrical signal lead-out terminals;

[0009] The encapsulation layer covers the electrode layer and the nanowire array, and a hydrogen permeation window is provided on the encapsulation layer to allow hydrogen gas to pass into the nanowire array.

[0010] Furthermore, the electrode layer, nanowire array, and conductive metal thin film layer corresponding to the hydrogen permeation window constitute a hydrogen measurement channel. A reference channel is also provided on the patch. The reference channel and the hydrogen measurement channel are isomorphic or approximately isomorphic in terms of the conductive metal thin film layer, electrode layer pattern, and electrode wiring structure. The nanowire array surface of the reference channel is covered with a barrier layer, which is connected to the surrounding encapsulation layer.

[0011] Furthermore, the functional layer, electrode layer, and encapsulation layer constitute a sensing unit, and an array of sensing units is disposed on the same flexible substrate.

[0012] Furthermore, the nanowires in the nanowire array are independent of each other and oriented along the normal direction of the flexible substrate. The structural parameters of the nanowire array include nanowire diameter, nanowire height and array spacing.

[0013] Finite element mechanical simulation or experimental calibration is used to optimize the structural parameters, with the critical constraints being that adjacent nanowires do not physically contact each other during bending and that the bottom of the nanowires does not break. The goal is to minimize the bending radius that matches the surface of the target device and meets the baseline resistance relative drift rate requirement.

[0014] Furthermore, an adhesive layer is provided between the flexible substrate and the functional layer; the electrode layer includes paired contact electrodes or interdigitated electrodes, which are formed on the top surface of the nanowire array after the functional layer has been transferred.

[0015] According to another aspect of this application, a method for preparing a flexible hydrogen leak sensing patch is provided, comprising:

[0016] An interface transition layer and a conductive metal thin film layer are sequentially formed on the top surface of a rigid substrate;

[0017] A nanowire array is formed on the top surface of a conductive metal thin film layer;

[0018] A soluble support layer is coated on a nanowire array; wherein the soluble support layer fills the gaps in the nanowire array and fixes the nanowires during the film formation process;

[0019] The composite film, which includes a soluble support layer, a nanowire array, and a conductive metal thin film layer, is peeled off from a rigid substrate and inverted and transferred to the top surface of a flexible substrate.

[0020] Remove the soluble support layer to expose the nanowire array, and form an electrode layer on the top surface of the exposed nanowire array;

[0021] The patch forming the electrode layer is encapsulated, and hydrogen permeation windows are opened on the encapsulation layer.

[0022] Furthermore, forming a nanowire array on the top surface of the conductive metal thin film layer includes: forming precursor nanowires on the top surface of the conductive metal thin film layer using a pore array template-assisted electrochemical deposition method, obtaining the nanowire array through in-situ or post-treatment oxidation, and removing the pore array template.

[0023] According to another aspect of this application, a hydrogen leak monitoring system is provided, comprising:

[0024] The above patch;

[0025] The signal processing module acquires the resistance value output from the patch, calculates the hydrogen response signal based on the change of the resistance value relative to the baseline resistance R0, and sends the hydrogen response signal to an external terminal; wherein, the hydrogen response signal is the resistance change ΔR = R - R0 and / or the relative resistance change ΔR / R0, where R is the resistance value.

[0026] Furthermore, if the patch is equipped with a hydrogen measurement channel and a reference channel, the signal processing module generates a compensated hydrogen response signal using a differential compensation method or a normalized differential compensation method based on the resistance value output by the hydrogen measurement channel and the resistance value output by the reference channel.

[0027] Furthermore, if the patch is a patch that includes an array of sensing units, the signal processing module also determines the location of the hydrogen leak based on the resistance value and coordinates of each sensing unit, and sends the location of the hydrogen leak to an external terminal.

[0028] The beneficial effects achieved by this invention are as follows: This invention realizes a hydrogen leakage sensing patch based on a flexible substrate, which can be directly attached to complex curved surfaces and has excellent conformal bonding characteristics. Furthermore, the functional layer of this invention is peeled off from the rigid substrate and transferred to the flexible substrate. The transfer process avoids the problems caused by the flexible substrate's inability to adapt to high temperatures and the surface roughness of the flexible substrate. Moreover, it can generate an ordered nanowire array, thereby eliminating resistance drift caused by contact point breakage or slippage and ensuring electrical stability under complex curved surface bonding. Attached Figure Description

[0029] Figure 1 A schematic diagram of the structure of a flexible hydrogen leak sensing patch;

[0030] Figure 2 Electron micrograph of the nanowire array;

[0031] Figure 3 This is a top view with two channels;

[0032] Figure 4 This is a two-channel sectional view;

[0033] Figure 5 A flowchart illustrating the preparation method of a flexible hydrogen leak sensing patch;

[0034] Figure 6 The diagram shows the dynamic response characteristics of a flexible hydrogen leak sensing patch under flat conditions.

[0035] Figure 7 A comparison graph showing the rate of change of resistance under bending conditions;

[0036] Figure 8 A schematic diagram for determining the location of a hydrogen leak;

[0037] Figure 9 A schematic diagram illustrating the first application scenario of the flexible hydrogen leak sensing patch;

[0038] Figure 10 This is a schematic diagram of a second application scenario for the flexible hydrogen leak sensing patch. Detailed Implementation

[0039] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this application or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0040] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application.

[0041] At the same time, it should be understood that, for ease of description, the dimensions of the various parts shown in the accompanying drawings are not drawn according to actual scale.

[0042] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0043] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0044] It should be noted that similar symbols and letters in the accompanying drawings represent similar items; therefore, once an item is defined in one accompanying drawing, it does not need to be discussed further in subsequent accompanying drawings.

[0045] See Figure 1 , Figure 1This is a schematic diagram of the structure of a flexible hydrogen leak sensing patch provided in an embodiment of this application. The patch may include at least a flexible substrate 1, a functional layer, an electrode layer 5, and an encapsulation layer 6. The functional layer is peeled off from the rigid substrate 9 and transferred to the flexible substrate 1. The functional layer may include at least a conductive metal thin film layer 3 attached to the top surface of the flexible substrate 1 and a nanowire array 4 attached to the top surface of the conductive metal thin film layer 3. The nanowires in the nanowire array 4 have resistance response characteristics to hydrogen. The electrode layer 5 is patterned on the top surface of the nanowire array 4 to form an electrical signal lead-out terminal. The encapsulation layer 6 covers the electrode layer 5 and the nanowire array 4, and a hydrogen permeation window 7 is provided on the encapsulation layer 6 to allow hydrogen to pass into the nanowire array 4.

[0046] It should be noted that the flexible substrate 1 is the main support structure of the patch and is a flexible polymer substrate. Its material can be a polymer film with high elastic recovery performance and chemical stability, such as polyimide, polydimethylsiloxane, thermoplastic polyurethane or its composite material. Its thickness can preferably be 50μm to 150μm to balance the mechanical strength and flexible bonding ability of the patch. The bottom surface of the flexible substrate 1 is the mounting surface, which can conform to the curved outer surface of high-pressure hydrogen storage tanks, hydrogen pipelines, valves and joints.

[0047] In some embodiments, to enhance the interfacial adhesion between the flexible substrate 1 and the conductive metal thin film layer 3, an adhesive layer 2 can be coated between the flexible substrate 1 and the conductive metal thin film layer 3. The adhesive layer 2 is uniformly coated on the top surface of the flexible substrate 1 to enhance the interfacial adhesion, thereby improving the reliability of structural fixation after transfer and preventing interlayer delamination of the patch during repeated bending. The adhesive layer 2 can be a cured elastomer thin layer or a flexible adhesive layer, such as a cured liquid polydimethylsiloxane elastomer thin layer or a modified acrylic flexible adhesive layer, with a thickness controlled between 5 μm and 20 μm.

[0048] It should be noted that the conductive metal thin film layer 3, which provides a stable electrical path and serves as the carrier / support structure for the nanowire array 4, is a dense metal thin film completely transferred from a rigid substrate 9 (such as a silicon wafer or glass) through a transfer process. Its material is preferably gold or platinum, and its thickness is preferably 50 nm to 100 nm. This conductive metal thin film layer 3 not only serves as the physical carrier platform for the nanowire array 4, maintaining its structural integrity through its flat surface, but can also be used as a common bottom electrode or conductive channel for the patch.

[0049] Nanowire array 4 can be a nanowire array made of p-type metal oxide, used to react with hydrogen gas and induce detectable changes in electrical parameters, such as resistance. Copper oxide or cuprous oxide nanowire arrays are preferred. The nanowires in nanowire array 4 are independent of each other (see details). Figure 2(Electron micrograph of the image), the nanowires are aligned along the normal direction of the flexible substrate 1 to reduce the fluctuation of the equivalent conductive path caused by collapse and abrupt changes in contact state when bending or fitting curved surfaces. The nanowires are independent of each other and maintain spacing to avoid collapse, entanglement and abrupt changes in contact state common in random interwoven structures during bending, fitting or slight stretching, thereby reducing contact resistance fluctuations caused by deformation and improving the stability of the electrical baseline.

[0050] It should be noted that the nanowire array 4 here can be formed by electrochemical deposition assisted by a porous array template, making the geometric parameters of the nanowires designable. Specifically, the pore size of the porous array template determines the nanowire diameter, the thickness / channel length of the porous array template and the electrodeposition time determine the nanowire height, and the pore spacing of the porous array template determines the array spacing (i.e., the nanowire spacing). By pre-selecting and optimizing the structural parameters of the nanowire array 4 (i.e., nanowire diameter, nanowire height, and array spacing), the structural stability and electrical baseline stability of the nanowire array 4 during the bending and bonding process can be improved while meeting the requirements for hydrogen response sensitivity and response time. Furthermore, the minimum bending radius Rmin of the patch under curved surface conditions of the target device can be designed.

[0051] In a hydrogen-free environment (e.g., air), the patch can be fixed on bending fixtures with different bending radii. After the resistance stabilizes, the baseline resistance R01 at the corresponding bending radius can be obtained. The baseline resistance R02 in the straight state or the specified reference state can be used as the baseline. The requirement of |R01-R02| / R02≤5% for the relative drift rate of the baseline resistance can be used. Finite element mechanical simulation calculation or experimental calibration can be used. The critical constraint conditions are that adjacent nanowires do not make physical contact during bending and the bottom of the nanowires does not break. The goal is to minimize the bending radius that matches the surface of the target device and meets the requirement of relative drift rate of the baseline resistance (i.e., |R01-R02| / R02≤5%). The structural parameters can be optimized, so that the minimum bending radius that matches the surface of the target device can be mapped while performing optimization calculations on the combination of structural parameters.

[0052] It should be noted that electrode layer 5, used to form positive and negative contact terminals and extract electrical signals, is preferably formed on the top surface of nanowire array 4 after the functional layer transfer is completed. It can be formed by screen printing or inkjet printing of conductive silver paste or carbon nanotube composite ink, thus avoiding the process problems caused by vacuum deposition or complex sensitive layer construction on flexible polymer substrates. Electrode layer 5 includes paired contact electrodes or interdigitated electrodes, which form electrical contacts with nanowire array 4 to extract resistance change signals. The top-contact structure of electrode layer 5 effectively avoids the process risks of high-temperature vacuum evaporation of electrodes 8 on flexible substrates.

[0053] It should be noted that the encapsulation layer 6 covers the outermost layer of the patch and is used for protection and long-term stability. The material can preferably be a hydrophobic and breathable polytetrafluoroethylene porous membrane or a breathable encapsulating adhesive. The hydrogen permeability window 7 of the encapsulation layer 6 can be of any shape, allowing hydrogen gas in the environment to diffuse through and contact the nanowire array 4 quickly, ensuring that hydrogen gas enters the sensitive area and achieves a response. Correspondingly, the surface of the nanowires corresponding to the hydrogen permeability window 7 remains exposed in the sensitive area to ensure that hydrogen molecules can reach and achieve a rapid response. At the same time, the part of the encapsulation layer 6 without the hydrogen permeability window 7 can effectively block external moisture, dust and mechanical friction from damaging the sensitive structure, thereby achieving long-term and stable online monitoring of hydrogen leakage on the surface of the hydrogen storage device.

[0054] To reduce the impact of ambient temperature fluctuations and bending deformation during the flexible bonding process on the electrical baseline, in some embodiments, see [reference needed]. Figure 3 A dual monitoring channel is constructed in the patch, defined as a hydrogen measurement channel and a reference channel, respectively. The hydrogen measurement channel is formed by the electrode layer 5, nanowire array 4 and conductive metal thin film layer 3 corresponding to the hydrogen permeation window 7. The reference channel can be set to avoid the hydrogen permeation window 7, but it is necessary to ensure that the reference channel and the hydrogen measurement channel are isomorphic or approximately isomorphic in the pattern of the conductive metal thin film layer 3, the electrode layer 5 and the wiring structure of the electrode 8, so that the two have similar intrinsic resistance drift characteristics under temperature changes, thermal expansion / contraction and bending stress.

[0055] The hydrogen measurement channel corresponds to hydrogen permeation window 7, exposing the corresponding nanowire to the external gas environment to output a hydrogen-sensitive resistance signal, defined as the hydrogen measurement resistance signal, specifically a resistance value. The reference channel is used to output a reference resistance signal (also a resistance value), see [link to relevant documentation]. Figure 4 The surface of the nanowire array 4 of the reference channel needs to be covered with a barrier layer, which is connected to the surrounding encapsulation layer 6. The barrier layer can suppress hydrogen diffusion into the sensitive interface of the reference channel. Therefore, the reference resistance signal mainly characterizes the baseline drift caused by temperature and mechanical deformation.

[0056] It should be noted that the barrier layer is a dense barrier layer, which can be at least one of a dense polymer thin layer or an inorganic dense thin layer. It covers the surface of the nanowire array 4 of the reference channel and is continuously connected to the surrounding encapsulation layer 6 to form a barrier path for hydrogen diffusion. The material and thickness of the dense barrier layer can be selected according to the target barrier performance and flexible adhesion requirements, so as to achieve low hydrogen permeability without significantly changing the bending and bonding ability of the patch.

[0057] It should be noted that during monitoring, compensation calculations can be performed based on the signals from the two channels to obtain the compensated hydrogen response signal. This can offset the common mode drift caused by temperature and mechanical deformation. The compensation method can be differential compensation or normalized differential compensation. For example, the two signals can be differentially divided to obtain the compensated signal, or the differential component can be normalized according to the reference resistance signal before output. This can improve the zero-point stability and anti-interference capability of hydrogen monitoring.

[0058] In some embodiments, a sensor unit array can be disposed on the same flexible substrate 1. The sensor unit is a unit composed of the functional layer, electrode layer 5 and encapsulation layer 6. This array arrangement can realize the monitoring of a large area, and can also locate the hydrogen leakage location within the coverage area based on the signal output by each sensor unit.

[0059] The aforementioned hydrogen leakage sensing patch based on the flexible substrate 1 can be directly attached to complex curved surfaces, exhibiting excellent conformal bonding characteristics. Furthermore, the functional layer of the patch is peeled off from the rigid substrate 9 and transferred to the flexible substrate 1. The transfer process avoids the problems caused by the flexible substrate 1's inability to adapt to high temperatures and the surface roughness of the flexible substrate 1, and can generate an ordered nanowire array 4. This can eliminate resistance drift caused by contact point breakage or slippage, ensuring electrical stability under complex curved surface bonding.

[0060] See Figure 5 , Figure 5 This is a flowchart illustrating a method for preparing a flexible hydrogen leak sensing patch according to an embodiment of this application. The method for preparing the patch may include at least the following steps:

[0061] Step 1: An interface transition layer 10 and a conductive metal thin film layer 3 are sequentially formed on the top surface of the rigid substrate 9.

[0062] It should be noted that a polished single-crystal silicon wafer or quartz glass with extremely low surface roughness can be selected as the rigid substrate 9. After removing surface organic matter and particulate impurities using a standard cleaning process, an interface transition layer 10 is deposited on the surface of the rigid substrate 9 using magnetron sputtering or electron beam evaporation. The interface transition layer 10 is preferably made of titanium, chromium, or a self-assembled monolayer, and its thickness is controlled at the nanoscale (e.g., 2 nm to 10 nm). Its function is to adjust the bonding energy between the upper metal layer and the rigid substrate 9, ensuring both the adhesion stability requirements of subsequent fabrication processes and low-damage interface separation during the transfer and peeling stage. Subsequently, a conductive metal thin film layer 3 with a thickness of 50 nm to 100 nm is deposited on the interface transition layer 10.

[0063] Step 2: Form a nanowire array 4 on the top surface of the conductive metal thin film layer 3.

[0064] In some embodiments, a porous array template can be used to assist electrochemical deposition to form a nanowire array 4, thereby enabling the designability of nanowire structure parameters.

[0065] A porous array template can be attached or constructed on the top surface of the conductive metal thin film layer 3. AAO (Anodic Aluminum Oxide) template is preferred. The pore size of the AAO template is preferably 20 nm to 200 nm, the pore spacing is preferably 40 nm to 500 nm, and the thickness (channel length) is preferably 0.5 μm to 50 μm. The pore size of the AAO template determines the nanowire diameter, the thickness / channel length of the AAO template and the electrodeposition time determine the nanowire height, and the pore spacing of the AAO template determines the array spacing.

[0066] After electrically connecting the bottom of the AAO template channels to the conductive metal thin film layer 3, AAO template-assisted electrochemical deposition is performed in an electrolyte system containing a copper salt precursor to obtain metal or metal oxide precursor nanowires of the desired height. After deposition, the formed precursor nanowires are subjected to in-situ or post-treatment oxidation, and heat-treated in air or an oxygen-containing atmosphere at 150 °C to 450 °C for 5 min to 180 min to obtain a vertically ordered nanowire array 4. Subsequently, the AAO template is gently dissolved, for example using an alkaline solution or a phosphoric acid system solution at room temperature to low temperature to minimize mechanical damage to the nanowire array 4.

[0067] Step 3: Cover the nanowire array 4 with a soluble support layer 11; wherein, the soluble support layer 11 fills the gaps in the nanowire array 4 and fixes the nanowires during the film formation process.

[0068] It should be noted that a polyvinyl alcohol aqueous solution with a mass fraction of 10wt% to 15wt% can be prepared and uniformly spin-coated or scraped onto the nanowire array 4. The solution is then dried and cured at a temperature of 60℃ to 90℃ to form a soluble support layer 11 with a thickness of 30μm to 60μm. This soluble support layer 11 penetrates into the pores of the nanowire array 4 and plays a role in coating and temporarily fixing the nanowires, which facilitates subsequent peeling and transfer.

[0069] Step 4: The composite film containing the soluble support layer 11, the nanowire array 4 and the conductive metal thin film layer 3 is peeled off from the rigid substrate 9 and transferred upside down to the top surface of the flexible substrate 1.

[0070] It should be noted that the composite film consisting of the soluble support layer 11, the nanowire array 4, and the conductive metal thin film layer 3 can be completely peeled off from the rigid substrate 9 using mechanical peeling. During this process, due to the presence of the interface transition layer 10, the peeling fracture surface occurs precisely between the conductive metal thin film layer 3 and the rigid substrate 9 (or inside the interface transition layer 10), thereby ensuring the integrity of the nanowire array 4 and the conductive metal thin film layer 3.

[0071] The peeled structure is flipped over so that the conductive metal thin film layer 3 faces downwards and the nanowire array 4 and soluble support layer 11 face upwards. Simultaneously, a flexible substrate 1 is prepared, and a layer of liquid polydimethylsiloxane elastomer or modified acrylic flexible adhesive is pre-coated onto its surface as an adhesive layer 2. The flipped structure is then flattened and adhered to the adhesive layer 2, and the adhesive layer 2 is cured under heating or ultraviolet light, thereby achieving permanent physical anchoring of the nanowire array 4 and the conductive metal thin film layer 3.

[0072] Step 5: Remove the soluble support layer 11 to expose the nanowire array 4, and form an electrode layer 5 on the top surface of the exposed nanowire array 4.

[0073] It should be noted that the bonded overall structure can be immersed in deionized water or pure water to fully dissolve the top soluble support layer 11 and allow it to be carried away by the water flow, thus cleanly exposing the underlying nanowire array 4. At this point, the vertically ordered nanowire array 4 has been successfully transferred to the flexible substrate 1 while maintaining the high-quality morphology grown on the rigid substrate 9. Subsequently, an electrode layer 5 is fabricated on the top surface of the nanowire array 4 using screen printing or inkjet printing processes.

[0074] Step 6: Encapsulate the patch forming electrode layer 5 and open hydrogen permeation window 7 on the encapsulation layer 6.

[0075] It should be noted that if dual monitoring channels are constructed in the patch, a dense barrier layer can be formed / set in the area corresponding to the reference channel during encapsulation to suppress hydrogen diffusion to the nanowire array 4 of the reference channel. The barrier layer and the encapsulation layer 6 are continuously connected, and no hydrogen permeation window 7 is opened in the area corresponding to the reference channel.

[0076] The above method employs a process route of prefabricating a conductive metal thin film layer 3 and a nanowire array 4 on a rigid substrate 9 and then transferring them to a flexible substrate 1. This avoids the process bottleneck of directly constructing a high-quality nanowire sensitive structure on a flexible polymer substrate, improving the consistency and repeatability of the sensitive structure. Furthermore, during the peeling and transfer process, a soluble support layer 11 penetrates into the gaps between the nanowire array 4 during film formation and encapsulates and temporarily fixes the nanowire array 4, thereby improving the structural integrity of the composite film peeling and flipping transfer process. Simultaneously, the interface transition layer 10 is used to balance the adhesion stability during the prefabrication stage and the low-damage, controllable separation during the peeling stage, so that the peeling fracture surface preferably occurs between the conductive metal thin film layer 3 and the rigid substrate 9 (or inside the interface transition layer 10), thereby reducing damage to the conductive metal thin film layer 3 and the nanowire structure.

[0077] Furthermore, the concentration, thickness, and film-forming / drying conditions of the soluble support layer 11 can be matched with the structural parameters of the nanowire array 4 and the parameters of the conductive metal thin film layer 3 / interface transition layer 10 (which can be determined through simulation calculation or experimental calibration) to improve the transfer yield and reduce the risk of damage or residue to sensitive structures. During the bonding stage, the permanent physical anchoring of the transferred conductive metal thin film layer 3 to the flexible substrate 1 is achieved through the curing of the adhesive layer 2, thereby improving the adhesion reliability and bending resistance stability after transfer. In addition, an electrode 8 is formed on the top surface of the nanowire array 4 after transfer. The process path is flexible and suitable for low-cost, large-area manufacturing. The prepared patch is a flexible and bendable structure, which is convenient for bonding to the curved outer surfaces of hydrogen storage tanks, pipelines, etc.

[0078] To verify the performance of the patch prepared by the above method, hydrogen dynamic response characteristics and bending mechanics tests were conducted.

[0079] 1) Conduct dynamic response characteristic tests on hydrogen;

[0080] The patch prepared using the above method was placed in a standard gas testing chamber. Under room temperature and standard atmospheric pressure, pure air and a 1% (volume ratio) mixed gas (hydrogen and air mixture) were alternately introduced into the testing chamber through a mass flow controller. The change rate of the patch's resistance over time was recorded, and the results are shown below. Figure 6 As shown, the test results indicate that when exposed to a 1% concentration of hydrogen, the resistance of the patch increases sharply within a very short time, with a relative resistance change of approximately 20%. After stopping the hydrogen flow and purging with air, the resistance quickly returns to its initial baseline level. This resistance change originates from the carrier concentration modulation caused by the reduction reaction between adsorbed oxygen and hydrogen on the p-type metal oxide surface. This demonstrates that the patch exhibits excellent sensitivity, rapid response, and good reversibility to low-concentration hydrogen, meeting the real-time requirements for early warning of hydrogen leaks.

[0081] 2) Bending mechanics test, specifically the resistance stability and anti-interference test under bending conditions;

[0082] To evaluate the signal reliability of the patch when bonded to a curved surface, the patch of this application and a control patch prepared using a conventional process (direct growth on a flexible substrate 1) were respectively fixed on a precision bending test platform. The changes and drift of baseline resistance under different bending radii and in a straight state were tested. The bending radius was defined by the radius of the cylindrical / arc clamp of the bending test platform; a smaller bending radius indicates a greater degree of bending. See the results below. Figure 7 For the control patch (shown by dashed lines), the rate of change of resistance increased significantly with increasing bending angle, with a baseline drift exceeding 16% under minimum bending radius conditions. This is mainly due to the change in the number of collapse and overlap points of the randomly interwoven nanostructures under bending / stretching, leading to significant fluctuations in contact resistance and equivalent conductive paths. In contrast, the patch of this application (shown by solid lines) exhibits extremely high electrical stability throughout the bending test range, with its rate of change of resistance controlled within 5% (typically less than 1%) even under minimum bending radius conditions.

[0083] By comparison Figure 6 and Figure 7 The data shows that the resistance change signal intensity caused by the reduction reaction of the patch in this application is significantly higher than the background noise caused by bending deformation. This strongly demonstrates that by introducing the conductive metal thin film layer 3 and the nanowire array 4 structure, this application has successfully achieved effective decoupling between the "gas response signal" and the "mechanical deformation signal", ensuring the detection accuracy in complex curved surface application scenarios.

[0084] In conjunction with the aforementioned patch, this application also relates to a hydrogen leak monitoring system, which may include at least the aforementioned patch and a signal processing module connected to the output terminal of the patch; wherein, the signal processing module acquires the resistance value output by the patch, calculates the hydrogen response signal based on the change of the resistance value relative to the baseline resistance R0, and sends the hydrogen response signal to an external terminal; wherein, the hydrogen response signal is the resistance change ΔR = R - R0 and / or the relative resistance change ΔR / R0, where R is the resistance value.

[0085] It should be noted that if the patch has dual monitoring channels, the signal processing module generates a compensated hydrogen response signal using a differential compensation method or a normalized differential compensation method based on the resistance value output from the hydrogen measurement channel and the resistance value output from the reference channel, and then sends the hydrogen response signal to the external terminal. Through the dual monitoring channel design and differential compensation algorithm, common-mode interference from ambient temperature fluctuations and substrate residual strain is effectively eliminated, solving the problem of false positives under complex operating conditions.

[0086] To verify the effectiveness of the dual-channel compensation, temperature and bending disturbance tests were performed on the patch. In the temperature disturbance test, the patch was placed in a temperature-controlled environment with varying ambient temperature. The baseline drift of the hydrogen resistance signal and the reference resistance signal was recorded as a function of temperature, and the drift amplitude of the output signal before and after compensation was compared. In the bending disturbance test, the patch was fixed on a bending test platform, and the baseline changes of the hydrogen resistance signal and the reference resistance signal were recorded under different bending radii. The deformation-related drift of the output signal before and after compensation was compared. The test results show that the reference channel can effectively characterize the intrinsic drift components caused by temperature and bending deformation. Dual-channel compensation calculation can significantly reduce the temperature drift and deformation drift of the output signal, thereby improving the reliability and stability of hydrogen leakage monitoring in complex curved surface application scenarios.

[0087] It should be noted that if there are multiple sensing units on the patch, the signal processing module also determines the hydrogen leak location based on the resistance value and coordinates of each sensing unit, and sends the hydrogen leak location to the external terminal.

[0088] See also Figure 8 The sensor unit array is 4×4 as an example, with each grid / space corresponding to one sensor unit. It should be understood that the number and arrangement of sensor units are not limited to 4×4, and can be an array with any number of rows and columns or other regular / irregular arrays. Each sensor unit adopts the above hierarchical structure and is connected to the signal processing module through multiplexing circuits or row and column addressing.

[0089] When hydrogen leaks at a point on the surface of a hydrogen storage device, the released hydrogen will create a concentration gradient distribution centered on the leak point within the patch-covered area (i.e., Figure 8 (The concentric circle region in the image). At this time, sensing units at different locations will output resistance signals (i.e., resistance values) of different amplitudes based on their distance from the leakage source. The signal processing module collects the signals from each sensing unit in real time and performs calculations using a weighted centroid positioning algorithm. Specifically, this algorithm uses the coordinates of each sensing unit as a reference and the change in the output signal strength as a weighting factor to calculate the coordinates of the "signal centroid" of the current leakage area. This effectively overcomes the deficiency of a single sensing unit that can only alarm but not locate, and can improve the positioning accuracy of the leakage point to sub-pixel resolution, thereby guiding maintenance personnel to quickly locate the fault area.

[0090] See Figure 9If the patch of the above system is attached to the cylindrical outer wall of a high-pressure hydrogen storage tank or hydrogen pipeline, the patch can integrate a miniaturized power management module and a low-power wireless communication module to transmit monitoring signals to an external terminal in real time via wireless communication. Once the concentration of leaked hydrogen exceeds a preset safety threshold, for example, when any sensor unit measures a hydrogen integral number ≥ 0.4 vol% (approximately 4000 ppm, about 10% of the lower limit flammable concentration of hydrogen in air, which is approximately equal to 4 vol%), the system immediately triggers an audible and visual alarm and / or a linkage alarm. The system also maps the physical coordinates of the sensor unit that triggered the safety threshold to its row and column address in the array, thereby displaying the specific location of the leak in the external terminal software.

[0091] Furthermore, thanks to the excellent flexibility and thinness of the patch, its application scenarios can be further expanded to the field of personal safety protection. For example... Figure 10 As shown, the patch can be worn as a wearable tag on the wrist of the worker or integrated into the surface of protective clothing. When inspection personnel enter a high-risk area and the ambient hydrogen concentration is abnormal, the patch can communicate with the worker's mobile terminal (such as an explosion-proof mobile phone or smartwatch) via Bluetooth to immediately issue an audible, visual, or vibration warning, thereby achieving proactive safety protection for personnel working with hydrogen.

[0092] The above description is only a preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A flexible hydrogen leak sensing patch, characterized in that, include: Flexible substrate; The functional layer includes a conductive metal thin film layer disposed on the top surface of the flexible substrate and a nanowire array disposed on the top surface of the conductive metal thin film layer; The functional layer is peeled off from the rigid substrate and transferred to the flexible substrate; the nanowires in the nanowire array have resistive response characteristics to hydrogen gas. An electrode layer, disposed on the top surface of the nanowire array, is used to form electrical signal lead-out terminals; The encapsulation layer covers the electrode layer and the nanowire array, and a hydrogen permeation window is provided on the encapsulation layer to allow hydrogen gas to pass into the nanowire array.

2. The patch according to claim 1, characterized in that, The electrode layer, nanowire array, and conductive metal thin film layer corresponding to the hydrogen permeation window constitute the hydrogen measurement channel. A reference channel is also provided on the patch. The reference channel is isomorphic or approximately isomorphic to the hydrogen measurement channel in terms of the conductive metal thin film layer, electrode layer pattern, and electrode wiring structure. The nanowire array surface of the reference channel is covered with a barrier layer, which is connected to the surrounding encapsulation layer.

3. The patch according to claim 1 or 2, characterized in that, A sensing unit is formed by a functional layer, an electrode layer, and an encapsulation layer, and an array of sensing units is disposed on the same flexible substrate.

4. The patch according to claim 1, characterized in that, The nanowires in the nanowire array are independent of each other and oriented along the normal of the flexible substrate. The structural parameters of the nanowire array include nanowire diameter, nanowire height and array spacing. Finite element mechanical simulation or experimental calibration is used to optimize the structural parameters, with the critical constraints being that adjacent nanowires do not physically contact each other during bending and that the bottom of the nanowires does not break. The goal is to minimize the bending radius that matches the surface of the target device and meets the baseline resistance relative drift rate requirement.

5. The patch according to claim 1, characterized in that, An adhesive layer is also provided between the flexible substrate and the functional layer; the electrode layer includes paired contact electrodes or interdigitated electrodes, which are formed on the top surface of the nanowire array after the functional layer has been transferred.

6. A method for preparing a flexible hydrogen leak sensing patch, characterized in that, The patch is the patch according to any one of claims 1 to 5, and the method includes: An interface transition layer and a conductive metal thin film layer are sequentially formed on the top surface of a rigid substrate; A nanowire array is formed on the top surface of a conductive metal thin film layer; A soluble support layer is coated on a nanowire array; wherein the soluble support layer fills the gaps in the nanowire array and fixes the nanowires during the film formation process; The composite film, which includes a soluble support layer, a nanowire array, and a conductive metal thin film layer, is peeled off from a rigid substrate and inverted and transferred to the top surface of a flexible substrate. Remove the soluble support layer to expose the nanowire array, and form an electrode layer on the top surface of the exposed nanowire array; The patch forming the electrode layer is encapsulated, and hydrogen permeation windows are opened on the encapsulation layer.

7. The method according to claim 6, characterized in that, A nanowire array is formed on the top surface of a conductive metal thin film layer, including: A precursor nanowire was formed on the top surface of a conductive metal thin film using a pore array template-assisted electrochemical deposition method. The nanowire array was then obtained by in-situ or post-treatment oxidation, and the pore array template was removed.

8. A hydrogen leak monitoring system, characterized in that, include: The patch according to any one of claims 1 to 5; The signal processing module acquires the resistance value output from the patch, calculates the hydrogen response signal based on the change of the resistance value relative to the baseline resistance R0, and sends the hydrogen response signal to an external terminal; wherein, the hydrogen response signal is the resistance change ΔR = R - R0 and / or the relative resistance change ΔR / R0, where R is the resistance value.

9. The system according to claim 8, characterized in that, If the patch is the patch as described in claim 2, the signal processing module generates a compensated hydrogen response signal using a differential compensation method or a normalized differential compensation method based on the resistance value output by the hydrogen measurement channel and the resistance value output by the reference channel.

10. The system according to claim 8, characterized in that, If the patch is the patch as described in claim 3, the signal processing module also determines the hydrogen leak location based on the resistance value and coordinates of each sensing unit, and sends the hydrogen leak location to an external terminal.

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