Nanowire hydrogen sensing chip and hydrogen leakage detection system and method

Abstract

The invention discloses a nanowire hydrogen sensing chip and a hydrogen leakage detection system and method.The chip comprises a substrate, a conductive seed crystal layer is arranged on the top face of the substrate, a physical isolation groove is formed in the conductive seed crystal layer, and a first nanowire array is arranged on the portion, on the first side of the physical isolation groove, of the top face of the conductive seed crystal layer; an electrode is arranged at the top end of the first nanowire array, and a second nanowire array is arranged on the top surface of the conductive seed crystal layer on the second side of the physical isolation groove. According to the invention, the first nanowire array and the second nanowire array are arranged on the same liner and are electrically isolated by the physical isolation groove, so that two different detection mechanisms are combined into the same chip, and the false alarm rate in a complex environment can be reduced by combining the detection results of the two detection mechanisms.

Description

Technical Field

[0001] This invention relates to a nanowire hydrogen sensing chip, a hydrogen leak detection system and method, belonging to the field of hydrogen detection technology. Background Technology

[0002] Hydrogen, as a highly efficient and clean energy source, is increasingly widely used in fuel cell vehicles, hydrogen refueling stations, and industrial production. However, hydrogen is colorless and odorless, and has an extremely wide explosion limit (4%-75%), making it highly susceptible to safety accidents. Therefore, developing high-performance hydrogen sensing chips is crucial for the safe utilization of hydrogen energy. Current miniaturized hydrogen sensing chips mainly employ a single detection mechanism, such as resistive sensors that detect hydrogen through chemical redox reactions. Chips with this single detection mechanism exhibit a certain false alarm rate in complex environments. Summary of the Invention

[0003] This invention provides a nanowire hydrogen sensing chip, a hydrogen leak detection system and method, which solves the problems disclosed in the background art.

[0004] According to one aspect of this application, a nanowire hydrogen sensing chip is provided, comprising a substrate, a conductive seed layer disposed on the top surface of the substrate, a physical isolation trench disposed on the conductive seed layer, a first nanowire array disposed on the top surface of the conductive seed layer on a first side of the physical isolation trench, an electrode disposed at the top of the first nanowire array, and a second nanowire array disposed on the top surface of the conductive seed layer on a second side of the physical isolation trench; wherein the structures on both sides of the physical isolation trench are electrically isolated, the first nanowire in the first nanowire array is a metal oxide semiconductor nanowire with resistive response characteristics to hydrogen, and the second nanowire in the second nanowire array is a core-shell structure nanowire with localized surface plasmon resonance response characteristics to hydrogen.

[0005] Furthermore, the first nanowire array is a vertically ordered cylindrical nanowire array.

[0006] Furthermore, a core-shell alloy transition layer is disposed between the core and shell of the second nanowire.

[0007] Furthermore, the electrodes are interdigitated electrodes, opposed electrodes, or multi-point array electrodes. By adjusting the electrode positions, the detection sensitivity of the conductive path can be optimized.

[0008] Furthermore, the first nanowire array is in a completely exposed state with no filler between the first nanowires; the second nanowire array is embedded or partially embedded in a hole array template, which is located on the top surface of the conductive seed layer.

[0009] According to another aspect of this application, a method for fabricating a nanowire hydrogen sensing chip is provided, wherein the chip is the aforementioned chip, and the fabrication method includes: A conductive seed layer and a hole array template are sequentially formed on the substrate surface; Etch physical isolation trenches to cut off the conductive seed layer and the hole array template; The physical isolation trench and the structure on the first side of the physical isolation trench are shielded, and the core material nanowires are formed in the pore array template channels on the second side of the physical isolation trench. The physical isolation trench and the second side structure of the physical isolation trench are shielded, and metal nanowires are formed in the pore array template channels on the first side of the physical isolation trench; Remove the shielding and perform thermal annealing in an oxygen-containing atmosphere to oxidize the metal nanowires into metal oxide semiconductor nanowires, thereby eliminating the defects in the core material nanowires. The hole array template on the second side of the physical isolation trench is enlarged to shield the physical isolation trench and the structure on the first side of the physical isolation trench, forming a shell on the surface of the core material nanowire; The template for the pore array was selectively removed, and an electrode was fabricated at the top of the first nanowire array.

[0010] According to another aspect of this application, a hydrogen leak detection system is provided, including a light source, a filter, a photodetector, a signal processing module, and the aforementioned chip; The light source is used to illuminate the second nanowire array of the chip, and the photodetector is used to detect the total intensity of the reflected or scattered light after passing through the filter; wherein, the reflected light is the light reflected by the second nanowire array, and the scattered light is the light scattered by the second nanowire array; the edge of the transmission spectral line of the filter is located at the point where the slope of the plasmon resonance absorption peak of the second nanowire array is the largest. The electrodes of the chip and the conductive seed layer containing the first nanowire array are connected to the input terminal of the signal processing module and output a resistance signal to the signal processing module. The output terminal of the photodetector is connected to the input terminal of the signal processing module and outputs a light intensity signal to the signal processing module. The signal processing module performs hydrogen leakage detection based on the resistance signal and the light intensity signal.

[0011] According to another aspect of this application, a method for detecting hydrogen leaks is provided, employing the aforementioned system for detection, the detection method comprising: Receive the resistance signal and the light intensity signal at the current moment; Calculate the rate of change of resistance and the rate of change of light intensity based on the current resistance signal, the current light intensity signal, the resistance reference value, and the light intensity reference value; Hydrogen leak detection is performed based on the rate of change of electrical resistance and the rate of change of light intensity.

[0012] Furthermore, hydrogen leak detection is performed based on the rate of change of electrical resistance and the rate of change of light intensity, including: If the rate of change of resistance is greater than the electrical drift threshold and the absolute value of the rate of change of light intensity is less than the optical stability threshold, then environmental drift is determined, the current resistance signal is updated to the resistance reference value, the hydrogen leak detection at the current moment ends, and the updated resistance reference value is used for the hydrogen leak detection at the next moment. If the jitter index of the light intensity change rate is greater than the jitter threshold and the absolute value of the resistance change rate is less than the electrical stability threshold, then the light source fluctuation or optical path noise is determined, the light intensity change at the current moment is ignored or the current leakage detection state is maintained unchanged, and the light intensity signal collected at the next moment is smoothed and filtered. If, within a preset time window, the absolute value of the rate of change of resistance is greater than the electrical response threshold, the absolute value of the rate of change of light intensity is greater than the optical response threshold, and the resistance signal and light intensity signal simultaneously undergo step changes with the direction of the step changes conforming to the preset hydrogen response characteristics, then a hydrogen leak is determined to have occurred.

[0013] Furthermore, the detection method also includes, if hydrogen leakage is detected, fusing the hydrogen concentration value corresponding to the resistance signal at the current moment and the hydrogen concentration value corresponding to the light intensity signal at the current moment, and outputting the fused hydrogen concentration value and leakage alarm status flag.

[0014] The beneficial effects achieved by this invention are as follows: 1. This invention sets a first nanowire array and a second nanowire array on the same pad and uses physical isolation trenches for electrical isolation, thereby combining two completely different detection mechanisms into the same chip. This allows for the combination of the detection results of both mechanisms, reducing the false alarm rate in complex environments. 2. The fabrication method of this invention uses a partitioned masking and step-by-step growth process, which cleverly solves the problem of compatible fabrication of two heterogeneous materials on the same pad, making it suitable for wafer-level mass production in semiconductor processes. 3. The system of this invention uses a "photodetector + filter + total light intensity detection" to replace the expensive and bulky spectrometer, which significantly reduces the cost of the optical detection side and shrinks the size to the chip level. Furthermore, by actively illuminating the second nanowire array with a light source, it solves the problem that "passive structural color" materials cannot work in environments without light, such as inside pipes and in the interlayer of storage tanks. 4. The detection method of this invention combines the detection results of different detection mechanisms. That is, hydrogen leakage is only judged when both detection results meet the preset conditions, effectively reducing the false alarm rate in complex environments. Moreover, it uses optical signals to identify and self-calibrate the baseline drift of electrical signals in real time. Attached Figure Description

[0015] Figure 1 This is a cross-sectional schematic diagram of a nanowire hydrogen sensing chip. Figure 2 Electron micrograph of the morphology of the first nanowire array; Figure 3 This is a schematic diagram of the fabrication method of a nanowire hydrogen sensor chip. Figure 4 This is a schematic diagram of the optical detection side in a hydrogen leak detection system. Figure 5 The redshift of the plasmon resonance absorption peak of the second nanowire array and the response spectrum at the edge of the narrowband filter; Figure 6 A flowchart of a hydrogen leak detection method; Figure 7 This is a time-domain detection diagram of the electrical detection side in a hydrogen leak detection system. Figure 8 This is a time-domain detection diagram of the optical detection side in a hydrogen leak detection system. Detailed Implementation

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] Furthermore, in the description of the embodiments of this application, the terms "first," "second," etc., are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance. Therefore, features defined with "first" or "second" may explicitly or implicitly include one or more features.

[0023] See Figure 1 , Figure 1 This is a cross-sectional schematic diagram of a nanowire hydrogen sensing chip provided in an embodiment of this application. The chip may include at least a substrate 1, a conductive seed layer 2 attached to the top surface of the substrate 1, a physical isolation trench 8 formed on the conductive seed layer 2, a first nanowire array 3 grown on the top surface of the conductive seed layer 2 on the first side of the physical isolation trench 8, and an electrode fabricated at the top of the first nanowire array 3. Figure 1 (Not shown in the drawing), a second nanowire array 4 is grown on the top surface of the conductive seed layer 2 on the second side of the physical isolation trench 8; wherein, the structures on both sides of the physical isolation trench 8 are electrically isolated, the first nanowire in the first nanowire array 3 is a metal oxide semiconductor nanowire with resistance response characteristics to hydrogen, and the second nanowire in the second nanowire array 4 is a core-shell structure nanowire with local surface plasmon resonance response characteristics to hydrogen.

[0024] It should be noted that substrate 1 can be made of silicon, quartz or glass as a support substrate. Here, silicon dioxide or silicon wafers with an oxide layer on the surface can be selected. The surface is flat and has good insulation, providing mechanical support for the growth of the nanostructure above.

[0025] The conductive seed layer 2 can be a gold film with a thickness of about 5nm-50nm that is sputtered onto the top surface of the substrate 1 by magnetron sputtering. This gold film runs through the entire region and serves as both a common cathode for subsequent electrochemical deposition and a nucleation site for nanowire growth.

[0026] The physical isolation groove 8 can be achieved through photolithography or mechanical scribing, from Figure 1 It can be seen that the physical isolation trench 8 penetrates the conductive seed crystal layer 2. Through the physical isolation trench 8, electrical isolation between the two sides of the structure is achieved, thereby effectively preventing the two sides of the structure from affecting each other.

[0027] See Figure 2The first nanowire array 3 is a vertically ordered cylindrical nanowire array, a structurally stable array obtained through template-confined growth and in-situ thermal oxidation. The first nanowires can be p-type semiconductor copper oxide nanowires, with a diameter of approximately 50 nm-100 nm and a height of approximately 1-3 μm. This array constitutes a semiconductor gas-sensitive layer for detecting resistance changes. Due to the extremely high specific surface area and nanoscale diameter of the copper oxide nanowires, the electron depletion layer formed by oxygen adsorption can penetrate the entire radial dimension of the wire, allowing the electron injection effect upon hydrogen introduction to cause a significant resistance change. Simultaneously, its vertically ordered cylindrical geometry significantly shortens the diffusion path of gas molecules, achieving a millisecond-level kinetic response. Benefiting from the high surface activity brought about by the nanoscale effect, this copper oxide nanowire array does not require traditional high-temperature heating; it only needs micro-heating at 40℃-80℃ or chip self-heating conditions to overcome the reaction energy barrier and obtain a significant resistance response signal, thereby significantly reducing the overall power consumption of the chip.

[0028] It should be noted that in order to detect the resistance change caused by the hydrogen reduction reaction, an electrode is connected to the top of the first nanowire array 3. Here, the conductive seed layer 2 can be used as a common cathode, so only the top of the first nanowire array 3 needs to be set with an electrode. The electrode can be an interdigitated electrode, a counter electrode, or a multi-point array electrode. Interdigitated electrodes are preferred, as they can increase the effective sampling area and reduce the contact resistance.

[0029] To further explore the chip's ultimate detection capabilities, the aforementioned electrode positions are highly configurable. By adjusting the electrode positions, the detection sensitivity of the conductive path can be optimized. Specifically, different equivalent conductive loops can be formed in the nanowire array by configuring different electrode positions (e.g., adjusting the finger spacing and width of the interdigitated electrodes, or using a multi-point array arrangement). This design allows for detection based on the density distribution characteristics of the nanowire growth, such as prioritizing the current path with the strongest signal response or the highest signal-to-noise ratio; or by using multiple electrode positions to construct a four-probe test circuit, effectively eliminating the interference of contact resistance on weak signals, thereby significantly improving the sensitivity and stability of the resistive response.

[0030] It should be noted that the second nanowire array 4 is a composite nanowire array, and each second nanowire may include an inner gold nanowire core 41 and an outer palladium shell 42. The gold nanowire core 41 ( Figure 1 The scalloped portion serves as the main body for exciting local surface plasmons, while the palladium shell 42, with a thickness of approximately 5nm-10nm, acts as a hydrogen trapping layer. This ultrathin palladium layer can rapidly adsorb hydrogen and undergo lattice expansion without completely shielding the optical properties of the internal gold nanowires.

[0031] In some embodiments, there is a core-shell alloy transition layer between the core and shell of the second nanowire, namely at the interface between the gold nanowire core 41 and the palladium shell 42. During and / or after the deposition of the palladium shell 42, a dense gold-palladium alloy transition layer is formed in situ due to interdiffusion / atomic mixing at the interface. This transition layer not only optimizes lattice matching and reduces interface defects, but more importantly, it significantly increases the effective contact surface area and provides more highly active hydrogen storage sites, thereby giving the chip higher response sensitivity and millisecond-level response speed.

[0032] The second nanowire array 4 is not connected to the resistance measurement circuit, but serves as an optical calibration reference. The intensity of reflected / scattered light of the entire array is adjusted by the change in refractive index after the palladium shell 42 absorbs hydrogen. It is located on the same planar substrate 1 as the first nanowire array 3, with a physical isolation groove 8 between them, so that they do not contact each other and ensure that the electrical signal and the optical signal are generated independently and do not interfere with each other.

[0033] In some embodiments, the first nanowire array 3 (electrical sensing unit) and the second nanowire array 4 (optical sensing unit) employ asymmetric support structures with functional differences. Specifically, the first nanowire array 3 is in a completely exposed state, that is, the original growth template (i.e., the pore array template) has been removed, so that there is no solid filler between the first nanowires; while the second nanowire array 4 is embedded or partially embedded in the pore array template (such as a porous anodic aluminum oxide template), which is located on the top surface of the conductive seed layer 2 and acts as a mechanical support framework for the second nanowire array 4.

[0034] This asymmetric support structure addresses the dual-modal detection requirements: the electrical region employs an exposed structure to maximize the gas contact area, thereby enhancing sensitivity; while the optical region retains template support to prevent the nanowires from agglomerating or collapsing during hydrogen absorption and expansion, ensuring structural stability and the reliability of the optical signal.

[0035] The chip described above grows a first nanowire array 3 and a second nanowire array 4 on the same pad and uses a physical isolation trench 8 for electrical isolation, thereby combining two completely different detection mechanisms into the same chip. This allows for the combination of the detection results of the two mechanisms, reducing the false alarm rate in complex environments.

[0036] See Figure 3 , Figure 3 This is a schematic diagram of a method for fabricating a nanowire hydrogen sensor chip according to an embodiment of this application. This fabrication method can be used to fabricate the aforementioned chip and may include at least the following steps: Step 1: A conductive seed layer 2 and a hole array template are sequentially formed on the surface of substrate 1.

[0037] For example, a clean silicon wafer or glass can be used as substrate 1. First, a gold film with a thickness of about 10 nm is deposited on the top surface of substrate 1 by magnetron sputtering as a conductive seed layer 2. Then, an aluminum layer with a thickness of 0.2 μm–5 μm (preferably 1 μm–3 μm) is deposited on the gold film. The thickness of the aluminum layer can be controlled by the deposition time to set the pore depth of the pore array template, thereby determining the height of the subsequent nanowires. The above sample is placed in an oxalic acid solution for constant-pressure anodic oxidation. The aluminum layer is transformed in situ into vertically ordered porous alumina until the oxidation front touches the bottom conductive seed layer 2. Current mutation is monitored to stop the oxidation. Finally, a short-term initial pore-expanding treatment is performed using a dilute sodium hydroxide solution to penetrate the bottom barrier layer of the pores, expose the bottom conductive seed layer 2, and ensure unobstructed conductivity of the pores.

[0038] Step 2: Etch the physical isolation trench 8 to cut off the conductive seed layer 2 and the hole array template.

[0039] A removable polymer protective layer (such as photoresist) can be coated at a predetermined junction between the electrical detection side and the optical detection side. A physical isolation groove 8 is etched at the junction by photolithography or mechanical scribing. This physical isolation groove 8 cuts off the lateral continuity of the alumina template and prevents the subsequent solution from spreading and contaminating laterally through the porous structure.

[0040] Step 3: Mask the physical isolation trench 8 and the first side structure of the physical isolation trench 8, and form a core material nanowire in the hole array template channel on the second side of the physical isolation trench 8.

[0041] The physical isolation tank 8 and the first side structure of the physical isolation tank 8 (i.e. the electrical detection side) can be completely covered by a polymer mask. The sample from step 2 is placed in the chloroauric acid plating solution, and constant current electrodeposition is performed with the bottom conductive seed layer 2 as the cathode. Gold atoms preferentially nucleate at the bottom of the second side channel and grow upward to form a dense gold nanowire framework.

[0042] Step 4: Mask the physical isolation trench 8 and the second side structure of the physical isolation trench 8, and form metal nanowires in the pore array template channel on the first side of the physical isolation trench 8.

[0043] Remove the polymer mask from the sample surface in step 3, and after cleaning, use the polymer mask to cover the physical isolation tank 8 and the second side structure of the physical isolation tank 8 (i.e., the optical detection side). Place the sample in the copper plating solution and electrochemically deposit copper nanowires in the first side channel.

[0044] Step 5: Remove the shielding and perform thermal annealing in an oxygen-containing atmosphere to oxidize the metal nanowires into metal oxide semiconductor nanowires, thereby eliminating defects in the core material nanowires.

[0045] After removing the polymer mask from the sample surface from step 4, the sample is placed in an oxygen-filled tube furnace and subjected to thermal annealing at 250℃-400℃. During this process, a key phase transformation occurs: copper nanowires are oxidized in situ to copper oxide semiconductor nanowires, grain rearrangement and fusion occur, and defects are reduced; gold nanowires, due to their chemical stability, maintain their elemental metallic state. During this heat treatment, gold nanowires undergo recrystallization and grain growth, eliminating microscopic defects such as grain boundaries, dislocations, and lattice vacancies generated during electrochemical deposition, and releasing internal residual stress.

[0046] Step 6: Expand the holes in the hole array template on the second side of the physical isolation trench 8 to cover the physical isolation trench 8 and the structure on the first side of the physical isolation trench 8, and form a shell with the core material nanowires.

[0047] The sample from step 5 is immersed in a dilute sodium hydroxide or phosphoric acid solution for secondary pore expansion, forming a distinct annular gap between the gold nanowires and the pore walls. Then, the physical isolation trench 8 and the first side structure of the physical isolation trench 8 are shielded. A palladium shell 42 is deposited on the surface of the gold nanowires by magnetron sputtering or chemical plating to form a composite nanowire. During and / or after the deposition of the palladium shell 42, spontaneous interdiffusion / atomic mixing occurs at the interface between the gold nanowire core 41 and the palladium shell 42 layer, forming a dense gold-palladium alloy transition layer at the interface.

[0048] Step 7: Selectively remove the pore array template and fabricate an electrode at the top of the first nanowire array 3.

[0049] Taking the aforementioned asymmetric support structure as an example, a polymer mask can be used to cover the physical isolation trench 8 and the second side structure of the physical isolation trench 8. The first side is immersed in a strong alkali or a specific corrosive liquid to completely dissolve the first side hole array template, so that the first nanowire array 3 is completely exposed to obtain the maximum gas-sensitive specific surface area. After removing the polymer mask, the second nanowire array 4 is buried or semi-buried in the hole array template, which can effectively prevent the collapse and aggregation of high-density gold nanowires.

[0050] The above-mentioned preparation method uses a partitioned masking and step-by-step growth process, which cleverly solves the problem of compatible preparation of two heterogeneous materials on the same substrate, making it suitable for wafer-level mass production in semiconductor processes.

[0051] This application also relates to a hydrogen leak detection system, see [link to relevant documentation] Figure 4 In addition to the aforementioned chip and signal processing module, the system mainly adds a light source 5, a filter, and a photodetector to the second nanowire array 4. The light source 5, the filter 6, and the photodetector 7 can be arranged separately as needed, or packaged together with the chip.

[0052] The light source 5 can be a miniature LED white light source. The light source 5 is used to provide illumination to the second nanowire array 4 of the chip. The light emitted by the light source 5 can be reflected or scattered by the second nanowire array 4. The reflected or scattered light is transmitted to the photodetector 7 through the filter 6.

[0053] The filter 6 can be closely attached to the window of the photodetector 7. The edge of the transmission spectral line of the filter 6 is located at the point where the slope of the plasmon resonance absorption peak of the second nanowire array 4 is the largest, which is used to convert the wavelength shift of the plasmon resonance absorption peak into a change in the intensity of transmitted light.

[0054] It should be noted that the filter element 6 can be a bandpass filter or a bandpass interference film; specifically, a narrowband filter is used here to selectively transmit light within the 630nm~690nm wavelength band and suppress light outside this band. At least one edge wavelength of the transmission band of the filter element 6 falls within the region of maximum slope in the plasmon resonance reflection / absorption spectrum. For example, when the plasmon resonance peak is approximately 650nm, the edge wavelength is preferably set to 660±5nm. Therefore, when the effect of hydrogen causes a slight shift in the plasmon resonance peak, the intensity of the incident light after passing through the filter element 6 (corresponding to the output of the photodetector 7) exhibits a significant step change, thereby enabling the detection of spectral shift effects without the need for a spectrophotometer.

[0055] The photodetector 7 can be a broadband photodetector to detect the total intensity of the reflected or scattered light after passing through the filter 6.

[0056] The electrodes of the chip and the conductive seed layer 2 where the first nanowire array 3 is located are connected to the input terminal of the signal processing module and output a resistance signal to the signal processing module. The output terminal of the photodetector 7 is connected to the input terminal of the signal processing module and outputs a light intensity signal to the signal processing module. The signal processing module performs hydrogen leakage detection based on the resistance signal and the light intensity signal.

[0057] It should be noted that the signal processing module mainly includes a front-end conditioning circuit, an analog-to-digital converter, and a microprocessor connected in sequence. The front-end conditioning circuit is connected to both the electrode and the photodetector 7, receiving the resistance signal output from the electrode and the light intensity signal output from the photodetector 7, and converting both signals into amplifiable voltage signals. The microprocessor is equipped with a detection program configured to simultaneously process the two signals, determining hydrogen leakage and calibrating for environmental drift based on the response difference between the resistance and light intensity signals, and outputting the fused hydrogen concentration data and alarm status.

[0058] The core working mechanism of the above system is as follows: See Figure 5 The solid curve represents the localized surface plasmon resonance absorption spectrum of the second nanowire array 4 in its initial state. The narrowband filter has a specific transmission window. Figure 5 As shown in the dashed box, the edge of its transmission band is precisely designed to fall at the wavelength corresponding to the maximum slope of the plasmon resonance absorption peak. For example, if the plasmon resonance absorption peak is located at 650nm, the edge of the narrowband filter can be selected to be near 660nm.

[0059] When hydrogen is present in the environment, the palladium shell 42 absorbs hydrogen and expands, causing a plasmonic resonance absorption peak in the second nanowire (e.g., ...). Figure 5 As shown by the dashed line, without a narrowband filter, the change in total light intensity (full spectrum integral) detected by photodetector 7 is extremely small and difficult to distinguish. However, in the above system, due to the redshift of the plasmon resonance absorption peak, the spectral energy that was originally in the cutoff region of the narrowband filter "slips" into the high transmission region (or the energy that was originally transmitted moves out of the window), such as... Figure 5 As shown in the shaded area, a tiny wavelength shift causes a dramatic change in the integrated area of ​​light energy transmitted through the narrowband filter. This means that the narrowband filter acts as an "optical amplifier," converting nanometer-scale wavelength shift signals into macroscopic light intensity step signals that can be easily detected by the photodetector 7. Therefore, the above system does not require an expensive and bulky spectrometer; high-sensitivity, low-cost hydrogen detection can be achieved using only ordinary silicon photodiodes.

[0060] The above system uses a "photodetector 7 + filter 6 + total light intensity detection" to replace the expensive and bulky spectrometer, which greatly reduces the cost of the optical detection side and shrinks the size to the chip level. Furthermore, by actively illuminating the second nanowire array 4 with the light source 5, it solves the problem that "passive structural color" materials cannot work in environments without light, such as inside pipes and in the interlayer of storage tanks.

[0061] See Figure 6 , Figure 6 This is a flowchart of a hydrogen leak detection method provided in an embodiment of this application. The detection method is implemented using the above-described system, specifically executed by a microprocessor within the system. The detection method may include at least the following steps: S1) Receives the resistance signal and the light intensity signal at the current moment.

[0062] The resistance signal and the light intensity signal at the current moment are acquired synchronously. That is, in each cycle, the resistance signal and the light intensity signal at the current moment are acquired synchronously through the analog-to-digital conversion unit, which can be denoted as R(t) and I(t) respectively.

[0063] S2) Calculate the rate of change of resistance and the rate of change of light intensity based on the resistance signal at the current moment, the light intensity signal at the current moment, the resistance reference value, and the light intensity reference value.

[0064] The calculation formula can be expressed as: S R =ΔR / R0; S I =ΔI / I0; In the formula, ΔR is the difference between the resistance signal and R0 at the current moment, ΔI is the difference between the light intensity signal and I0 at the current moment, R0 and I0 are the resistance reference value and the light intensity reference value, respectively, and S R and S I These represent the rate of change of resistance and the rate of change of light intensity, respectively; and are the normalized response quantities of the electrical channel and the optical channel, respectively. If necessary, S can be... R and S I Perform moving average or low-pass filtering to improve noise immunity.

[0065] S3) Hydrogen leak detection is performed based on the rate of change of resistance and the rate of change of light intensity.

[0066] The specific detection logic can be as follows: a. If the rate of change of resistance is greater than the electrical drift threshold and the absolute value of the rate of change of light intensity is less than the optical stability threshold, then environmental drift is determined, the current resistance signal is updated to the reference value of resistance, the hydrogen leak detection at the current moment ends, and the updated reference value of resistance is used for the hydrogen leak detection at the next moment. The electrical drift threshold is set to 10% to distinguish between slow temperature and humidity drift and violent hydrogen response; the optical stability threshold is set to 2%, which is slightly higher than the background noise level of the system's optical path.

[0067] Based on the above criteria, it can be determined that when there is a significant change in the electrical channel while the optical channel remains stable, it is due to environmental drift rather than hydrogen leakage. In this case, a baseline calibration / zeroing operation needs to be performed, i.e., the current resistance signal is updated to the reference resistance value.

[0068] b. If the jitter index of the light intensity change rate is greater than the jitter threshold and the absolute value of the resistance change rate is less than the electrical stability threshold, then the light source 5 is judged to be fluctuating or the optical path is noisy. The hydrogen leakage detection at the current moment is terminated, that is, the light intensity change at the current moment is ignored or the current leakage detection state is maintained unchanged, and the light intensity signal collected at the next moment is subjected to smoothing filtering. Among them, frequency domain energy, short window variance or first-order differential amplitude can be used as jitter index; the jitter threshold can be set to 0.8% of the light intensity reference value (calculated in standard deviation) to identify transient oscillations in the optical path caused by non-gas-sensitive reactions; the electrical stability threshold can be set to 5% to ensure that the electrical channel is indeed in a hydrogen-free reaction state when the optical path fault is judged.

[0069] Based on the above criteria, if high-frequency jitter or slight fluctuations are detected in the optical channel while the electrical channel remains stable, indicating fluctuations in light source 5 or optical path noise, filtering / smoothing processing will be performed on the light intensity signal to avoid false alarms caused by transient disturbances in the optical link.

[0070] c. If, within a preset time window (the length of which depends on the time conditions, such as 20 seconds), the absolute value of the resistance change rate is greater than the electrical response threshold, the absolute value of the light intensity change rate is greater than the optical response threshold, and both the resistance and light intensity signals undergo simultaneous step changes with the directions of these changes conforming to the preset hydrogen response characteristics, then a hydrogen leak is determined to have occurred. The electrical response threshold can be set to 30%, and the optical response threshold can be set to 8%. This setting is based on experimental data: when the hydrogen concentration reaches 10% of the lower explosive limit, the resistance change of copper oxide typically exceeds 50%, while the light intensity change caused by gold and palladium is approximately 10%-15%. The above threshold settings effectively cover the detection range and eliminate false alarms.

[0071] The above detection method combines the detection results of different detection mechanisms. Only when two detection results meet the preset conditions can hydrogen leakage be judged, which effectively reduces the false alarm rate in complex environments. Furthermore, it uses optical signals to identify and self-calibrate the baseline drift of electrical signals in real time, which can solve the baseline drift problem that is common in metal oxide sensors.

[0072] It should be noted that, in some embodiments, if a hydrogen leak is detected, the hydrogen concentration value corresponding to the resistance signal at the current moment and the hydrogen concentration value corresponding to the light intensity signal at the current moment are fused and calculated, and the fused hydrogen concentration value and the leak alarm status flag are output; wherein, the fusion can be implemented by weighted average or Kalman filtering algorithm.

[0073] To validate the system incorporating the aforementioned detection methods, time-domain testing was conducted. From Figure 7 and Figure 8 As can be seen, within the 0s-40s interval, the electrical channel (i.e., the electrical detection side) exhibits a slow, gradual baseline drift due to environmental interference, while the optical channel (optical detection side) remains near zero without any abrupt changes. Based on this, the system determines that the change is due to environmental drift rather than hydrogen leakage and triggers a baseline reset at approximately 40s, restoring the electrical channel to a stable baseline. The results indicate that the stability of the optical channel can be used for real-time identification and self-calibration of electrical channel drift, avoiding false alarms caused by single-channel drift and thus improving safety. After introducing hydrogen at approximately 70s, the electrical channel exhibits a significant abrupt change and tends to stabilize, while the optical channel also shows a synchronous abrupt change. The system triggers a leak detection and outputs the concentration result only when both channels simultaneously cross the threshold and the direction of change conforms to the preset hydrogen response model, thereby improving alarm confidence and reducing the risk of false alarms / missed alarms.

[0074] In conclusion, Figure 7 and Figure 8Data proves that the system achieves drift elimination and baseline reset through the complementary characteristics of "electrical drift and optical stability", and realizes dual-channel synchronous response under real hydrogen events, thus achieving low false alarm and high safety hydrogen leakage monitoring at the system level.

[0075] 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 nanowire hydrogen sensing chip, characterized in that, The device includes a substrate, a conductive seed layer on the top surface of the substrate, a physical isolation trench on the conductive seed layer, a first nanowire array on the top surface of the conductive seed layer on the first side of the physical isolation trench, an electrode on the top of the first nanowire array, and a second nanowire array on the top surface of the conductive seed layer on the second side of the physical isolation trench. The physical isolation trench is electrically isolated from the structure on both sides. The first nanowire in the first nanowire array is a metal oxide semiconductor nanowire with resistive response characteristics to hydrogen, and the second nanowire in the second nanowire array is a core-shell nanowire with localized surface plasmon resonance response characteristics to hydrogen.

2. The chip according to claim 1, characterized in that, The first nanowire array is a vertically ordered cylindrical nanowire array.

3. The chip according to claim 1, characterized in that, A core-shell alloy transition layer is provided between the core and shell of the second nanowire.

4. The chip according to claim 1, characterized in that, The electrodes are interdigitated electrodes, opposed electrodes, or multi-point array electrodes. By adjusting the electrode positions, the detection sensitivity of the conductive path is optimized.

5. The chip according to any one of claims 1 to 4, characterized in that, The first nanowire array is completely exposed, with no filler between the nanowires; the second nanowire array is embedded or partially embedded in a hole array template, which is located on the top surface of the conductive seed layer.

6. A method for fabricating a nanowire hydrogen sensing chip, characterized in that, The chip is the chip according to any one of claims 1 to 5, and the preparation method includes: A conductive seed layer and a hole array template are sequentially formed on the substrate surface; Etch physical isolation trenches to cut off the conductive seed layer and the hole array template; The physical isolation trench and the structure on the first side of the physical isolation trench are shielded, and the core material nanowires are formed in the pore array template channels on the second side of the physical isolation trench. The physical isolation trench and the second side structure of the physical isolation trench are shielded, and metal nanowires are formed in the pore array template channels on the first side of the physical isolation trench; Remove the shielding and perform thermal annealing in an oxygen-containing atmosphere to oxidize the metal nanowires into metal oxide semiconductor nanowires, thereby eliminating the defects in the core material nanowires. The hole array template on the second side of the physical isolation trench is enlarged to shield the physical isolation trench and the structure on the first side of the physical isolation trench, forming a shell on the surface of the core material nanowire; The template for the pore array was selectively removed, and an electrode was fabricated at the top of the first nanowire array.

7. A hydrogen leak detection system, characterized in that, It includes a light source, a filter, a photodetector, a signal processing module, and the chip described in any one of claims 1 to 5; The light source is used to illuminate the second nanowire array of the chip, and the photodetector is used to detect the total intensity of the reflected or scattered light after passing through the filter; wherein, the reflected light is the light reflected by the second nanowire array, and the scattered light is the light scattered by the second nanowire array; the edge of the transmission spectral line of the filter is located at the point where the slope of the plasmon resonance absorption peak of the second nanowire array is the largest. The electrodes of the chip and the conductive seed layer containing the first nanowire array are connected to the input terminal of the signal processing module and output a resistance signal to the signal processing module. The output terminal of the photodetector is connected to the input terminal of the signal processing module and outputs a light intensity signal to the signal processing module. The signal processing module performs hydrogen leakage detection based on the resistance signal and the light intensity signal.

8. A method for detecting hydrogen leaks, characterized in that, The detection is performed using the system described in claim 7, and the detection method includes: Receive the resistance signal and the light intensity signal at the current moment; Calculate the rate of change of resistance and the rate of change of light intensity based on the current resistance signal, the current light intensity signal, the resistance reference value, and the light intensity reference value; Hydrogen leak detection is performed based on the rate of change of electrical resistance and the rate of change of light intensity.

9. The method according to claim 8, characterized in that, Hydrogen leak detection is performed based on the rate of change of electrical resistance and the rate of change of light intensity, including: If the rate of change of resistance is greater than the electrical drift threshold and the absolute value of the rate of change of light intensity is less than the optical stability threshold, then environmental drift is determined, the current resistance signal is updated to the resistance reference value, the hydrogen leak detection at the current moment ends, and the updated resistance reference value is used for the hydrogen leak detection at the next moment. If the jitter index of the light intensity change rate is greater than the jitter threshold and the absolute value of the resistance change rate is less than the electrical stability threshold, then the light source fluctuation or optical path noise is determined, the light intensity change at the current moment is ignored or the current leakage detection state is maintained unchanged, and the light intensity signal collected at the next moment is smoothed and filtered. If, within a preset time window, the absolute value of the rate of change of resistance is greater than the electrical response threshold, the absolute value of the rate of change of light intensity is greater than the optical response threshold, and the resistance signal and light intensity signal simultaneously undergo step changes with the direction of the step changes conforming to the preset hydrogen response characteristics, then a hydrogen leak is determined to have occurred.

10. The method according to claim 8 or 9, characterized in that, The detection method further includes, if hydrogen leakage is detected, fusing the hydrogen concentration value corresponding to the resistance signal at the current moment and the hydrogen concentration value corresponding to the light intensity signal at the current moment, and outputting the fused hydrogen concentration value and leakage alarm status flag.

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