A slit diffraction type hydrogen detection device and a method for preparing a membrane plate

Abstract

The present invention belongs to the technical field of hydrogen sensors, and particularly relates to a slit diffraction type hydrogen detection device and a template preparation method. It includes an air chamber, a template arranged in the air chamber, a first lens arranged in parallel on one side of the template, a second lens arranged in parallel on the other side of the template, a laser diode located at the focal length on the side of the first lens away from the template, and an observation screen located at the focal length on the side of the second lens away from the template. The template includes a silicon oxide layer, a metal palladium layer arranged on the surface of the silicon oxide layer, and a slit penetrating the double-layer film. The technical solution provided by the present invention reflects the change of hydrogen concentration through the change of the slit diffraction pattern formed by a Pd / SiO2 double-layer film with a slit. The designed sensor has a simple structure, is sensitive, low in cost, and high in safety, and is particularly suitable for directly monitoring the hydrogen concentration in areas with complex working conditions.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen sensors, and particularly relates to a slit diffraction type hydrogen detection device and a template preparation method. Background Art

[0002] A hydrogen sensor is a sensor device that detects hydrogen and generates a signal proportional to the hydrogen concentration. It has advantages such as low cost, small size, and fast response compared with traditional hydrogen detection methods (gas chromatograph, mass spectrometer).

[0003] The interaction between hydrogen and the sensing element of the hydrogen sensor can cause changes in temperature, refractive index, electrical properties, mass, or mechanical structure. According to the different physical quantities detected, hydrogen sensors are divided into catalytic type, thermal conductivity type, electrochemical type, resistive type, work function type, mechanical type, optical type, and acoustic type. Compared with other types of hydrogen sensors, optical sensors are safer and do not involve circuit risks; secondly, because their original signal is an optical signal rather than an electrical signal, their sensitivity to electromagnetic noise is lower than that of other types of sensors; in addition, such sensors can perform real-time tracking monitoring.

[0004] There are many types of sensors that use optical changes for detection in the prior art, such as interference type, grating type, etc. For example, Chinese Patent CN104132914A provides a Mach-Zehnder micro-nano fiber interference type hydrogen sensor based on palladium alloy nanowires. Chinese Patent CN1071101960A provides a micro-nano fiber Michelson interferometric hydrogen sensor.

[0005] However, there is no report on hydrogen sensors developed based on the principle of slit diffraction. Summary of the Invention

[0006] The present invention provides a slit diffraction type hydrogen detection device and a template preparation method to solve the problem of the lack of slit diffraction type hydrogen detection methods currently.

[0007] To solve the above technical problems, the technical solution of the present invention is: the slit diffraction type hydrogen detection device includes an air chamber, a template disposed in the air chamber, a first lens disposed parallel to one side of the template, a second lens disposed parallel to the other side of the template, a laser diode located at the focal length on the side of the first lens away from the template, and an observation screen located at the focal length on the side of the second lens away from the template. The template includes a silicon oxide layer, a metal palladium layer disposed on the surface of the silicon oxide layer, and a slit penetrating the double-layer film.

[0008] Optionally, the thickness of the silicon oxide layer is 1-2 μm, and the thickness of the metal palladium layer is 0.1-0.5 μm.

[0009] Optionally, the cross-section of the slit is a trapezoid, with the long bottom side located on one surface of the silicon oxide layer and the short bottom side located on one surface of the palladium metal layer.

[0010] Optionally, the angle between the long bottom side and the waist of the trapezoid is 65 - 80°.

[0011] Optionally, a photodetector is provided in the direction perpendicular to the slit on the observation screen for recording the diffraction light intensity distribution.

[0012] Optionally, the gas chamber is provided with an intake valve and an exhaust valve. On the laser optical path, a leading light cylinder for setting a first lens and a trailing light cylinder for setting a second lens extend from the gas chamber.

[0013] The present invention also provides a method for preparing the above-mentioned template, which includes the following steps:

[0014] S1: Coating a photoresist coating on a substrate and setting a linear mask, and forming a linear mask print on the photoresist coating through photolithographic exposure;

[0015] S2: After development processing, the linear photolithographic structure remains on the substrate, and a photolithographic straight line with a trapezoidal cross-section is formed after chloroform treatment;

[0016] S3: Using a coating technology to deposit a layer of silicon oxide layer on the substrate, and then in-situ depositing a layer of palladium metal layer on the surface of the silicon oxide layer;

[0017] S4: After removing the photoresist with a solvent and stripping the substrate, a Pd / SiO2 double-layer thin film with a slit is obtained.

[0018] Optionally, in S1, the thickness of the photoresist coating is 2 - 5 μm, and the width of the linear mask is 0.6 - 1 μm.

[0019] Optionally, in S3, the coating technology is selected from radio frequency magnetron sputtering, pulsed laser deposition or electron beam evaporation.

[0020] Optionally, when the coating technology is radio frequency magnetron sputtering, the background vacuum is < 10 -7 Pa, the deposition temperature is room temperature, the coating atmosphere is a mixed gas of argon and oxygen, the sputtering pressure is 10 - 200 Pa, and the radio frequency power is 20 - 300 W.

[0021] The present invention also provides a method for monitoring hydrogen concentration, which uses the above-mentioned slit diffraction type hydrogen detection device, and includes the following steps:

[0022] First, introduce multiple groups of hydrogen with standard concentrations into the gas chamber, and record the change values of the slit width corresponding to different concentrations of hydrogen;

[0023] Then, evacuate the gas chamber, turn on the laser diode, and record a set of initial diffraction patterns presented on the observation screen;

[0024] Subsequently, introduce the hydrogen gas to be measured into the gas chamber. A set of changed diffraction patterns will be presented on the observation screen. Estimate the change value of the slit width from the position of the limit value of the diffraction spectrum. By referring to the pre-calibrated relationship diagram or table between the hydrogen content and the change value of the slit width, the hydrogen content in the gas chamber at this time can be known.

[0025] The technical solution provided by the present invention uses a Pd / SiO2 double-layer film with a slit to reflect the change of hydrogen concentration through the change of the slit diffraction pattern. The designed sensor has a simple structure, high sensitivity, low cost, and high safety, and is especially suitable for directly monitoring the hydrogen concentration in areas with complex working conditions. Description of the Drawings

[0026] Figure 1 is a schematic diagram of the preparation process of the template of the present invention;

[0027] Figure 2 is a schematic diagram of the principle of the slit diffraction type hydrogen detection device of the present invention;

[0028] Figure 3 is a schematic structural diagram of a specific embodiment of the slit diffraction type hydrogen detection device of the present invention;

[0029] Figure 4 is the diffraction pattern presented on the observation screen of the present invention.

[0030] As shown in the figure:

[0031] 11 - Substrate, 12 - Photoresist coating, 13 - Linear mask, 14 - Photolithography line, 21 - Silicon oxide layer, 22 - Palladium metal layer, 23 - Slit, 30 - Gas chamber, 31 - Inlet valve, 32 - Outlet valve, 33 - Front light guide tube, 34 - Rear light guide tube, 41 - First lens, 42 - Second lens, 50 - Laser diode, 60 - Observation screen. Detailed Embodiments

[0032] For the convenience of understanding, the following describes the slit diffraction type hydrogen detection device and the template preparation method in combination with embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention.

[0033] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation and positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0034] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "connected", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0035] The preparation method of the template described in the present invention is as follows:

[0036] S1: As shown in Figures 1a and 1b, in a clean room, a photoresist coating 12 with a thickness exceeding 2 μm is coated on the surface of a double-sided polished sapphire single crystal substrate 11 by a high-speed centrifugal spin coater. The thickness of the substrate 11 is 0.1 - 0.5 mm, and the size of the substrate 11 is not limited, about 1 - 10 cm. Figure 1 The rotation speed of the centrifuge is about 200 - 3000 revolutions per minute and is dried at 100 - 120 °C; a linear mask plate 13 with a width of 0.6 - 1 μm is set on the surface of the photoresist coating 12, and a straight line mask print is formed on the photoresist coating 12 using a standard photolithography exposure process. 2 After that, a linear photolithography structure remains on the sapphire substrate 11 after development treatment, and then a photolithography straight line 14 with an isosceles trapezoidal cross-section is formed through normal chloroform treatment.

[0037] S2: As shown in Figure 1c, Figure 1 After development treatment, the linear photolithography structure remains on the sapphire substrate 11, and then a photolithography straight line 14 with an isosceles trapezoidal cross-section is formed through normal chloroform treatment.

[0038] S3: As shown in Figure 1d, Figure 1 Using the usual PVC coating technology (such as sputtering, pulsed laser deposition, electron beam evaporation, etc.), a silicon oxide layer 21 with a thickness of about 1 - 2 μm is deposited, and then a layer of palladium metal layer 22 is deposited in-situ on the silicon oxide layer 21. The thickness of the silicon oxide layer 21 is 1 - 2 μm, and the thickness of the palladium metal layer 22 is about 0.1 - 0.5 μm. The coating parameters vary according to the coating technology used. For example, for radio frequency magnetron sputtering, it can be referred to: background vacuum < 10 -7Pa, the deposition temperature is room temperature, sputtering targets: pure silicon and pure palladium. Silicon oxide can be deposited by reactive sputtering, coating atmosphere: Ar + O2 (Ar / O2 ratio 1:1 to 5:1), and metallic palladium is sputtered with pure Ar. Sputtering pressure: 10 - 200 Pa. The RF power depends on the size of the target, about 20 - 300 W;

[0039] S4: As Figure 1 shown in e, after removing the photoresist with acetone and peeling off the substrate 11, a Pd / SiO2 double-layer film with long slits, namely the template 20, is obtained. The cross-section of the slit 23 on the template 20 is a trapezoid, with the long bottom side located on one surface of the silicon oxide layer 21 and the short bottom side located on one surface of the metallic palladium layer 22. The included angle between the long bottom side and the waist of the trapezoid is about 70°.

[0040] Based on the principle of slit diffraction, the prepared template is used in this embodiment to detect the hydrogen concentration. The specific inventive concept is as Figure 2 [[ID=]

[10] ]shown. The laser with a wavelength of λ passes through the first lens 41, the slit 23 of the template 20, and the second lens 42 in sequence, and a diffraction spectrum will be formed at the focal length of the second lens 42.

[0041] According to the Fraunhofer single-slit diffraction theory, the light intensity distribution of the diffraction spectrum is:

[0042]

[0043] where (m is an integer, representing the m-th order diffraction peak). When bsinθ m = mλ, the diffraction spectrum shows a minimum value I(θ) = 0. At this time, the slit width

[0044] The deflection angle corresponding to the m-th order minimum value without oxygen is denoted as θ mo , when hydrogen is introduced, due to the Hile effect, the volume of metallic palladium will expand accordingly, resulting in a narrowing of the slit width. This minute change in the slit width can be directly observed on the single-slit diffraction spectrum. The change Δb in the slit width b can be estimated from the position of the extreme value of the diffraction spectrum. The relationship between the two can be reflected by the following formula:

[0045]

[0046] Based on the above inventive concept, this embodiment provides a slit diffraction type hydrogen detection device, as Figure 3As shown in the figure, it includes an air chamber 30, a diaphragm 20 disposed in the air chamber 30, a first lens 41 disposed in parallel on the side of the silicon oxide layer 21, a second lens 42 disposed in parallel on the side of the palladium metal layer 22, a laser diode 50 located at the focal length on the side of the first lens 41 away from the diaphragm 20, and an observation screen 60 located at the focal length on the side of the second lens 42 away from the diaphragm 20. The air chamber 30 is a closed space. An intake valve 31 and an exhaust valve 32 are provided on the side surface of the air chamber 30 through which the light path does not pass. The slit 23 of the diaphragm 20 is located on the laser light path. Preferably, the intake valve 31 and the exhaust valve 32 are located on two opposite side surfaces.

[0047] To improve the test sensitivity, the focal lengths of the first lens 41 and the second lens 42, especially the focal length of the second lens 42, are preferably selected to be large. Please continue to refer to Figure 3 , on the laser light path of the air chamber 30, a front light guide cylinder 33 for setting the first lens 41 and a rear light guide cylinder 34 for setting the second lens 42 are respectively extended.

[0048] Optionally, a photodetector (not shown in the figure) is provided in the direction perpendicular to the slit of the observation screen 60, which can be used to record the diffraction light intensity distribution.

[0049] The method for monitoring the hydrogen concentration using the above slit diffraction type hydrogen detection device is as follows:

[0050] First, introduce multiple groups of hydrogen with standard concentrations into the air chamber, and record the corresponding change values of the slit width when introducing hydrogen with different concentrations.

[0051] Then, evacuate the air chamber, turn on the laser diode, and record a set of standard Fraunhofer single slit diffraction patterns presented on the observation screen (as Figure 4 shown), that is, the initial diffraction pattern.

[0052] Subsequently, introduce the hydrogen to be measured into the air chamber. A set of changed diffraction patterns will be presented on the observation screen. Estimate the change value of the slit width from the limit position of the diffraction spectrum, and refer to the pre-calibrated relationship diagram or table between the hydrogen content and the change value of the slit width, then the hydrogen content in the air chamber at this time can be known.

[0053] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features, and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A slit diffraction type hydrogen detection device, characterized in that Comprising: A gas chamber; A diaphragm disposed in the gas chamber, the diaphragm comprising a silicon oxide layer, a palladium metal layer disposed on the surface of the silicon oxide layer, and a slit penetrating the double-layer film; A first lens disposed parallel to one side of the silicon oxide layer; A second lens disposed parallel to one side of the palladium metal layer; A laser diode located at the focal length on the side of the first lens away from the diaphragm, and an observation screen located at the focal length on the side of the second lens away from the diaphragm; The slit of the diaphragm is located on the laser light path. Laser with a wavelength of λ passes through the first lens, the slit of the diaphragm, and the second lens in sequence, and a diffraction spectrum is formed at the focal length of the second lens. The cross-section of the slit is a trapezoid, with the long bottom side located on the surface of the silicon oxide layer side and the short bottom side located on the surface of the palladium metal layer side. The included angle between the long bottom side and the waist of the trapezoid is 65 - 80°.

2. The slit diffraction type hydrogen detection device according to claim 1, characterized in that, The thickness of the silicon oxide layer is 1 - 2 μm, and the thickness of the palladium metal layer is 0.1 - 0.5 μm.

3. The slit diffraction type hydrogen detection device according to claim 1, characterized in that, A photodetector is disposed in the direction perpendicular to the slit of the observation screen for recording the diffraction light intensity distribution.

4. The slit diffraction type hydrogen detection device according to claim 1, wherein The gas chamber is provided with an intake valve and an exhaust valve. In the laser light path, the gas chamber extends a front light guide cylinder for setting the first lens and a rear light guide cylinder for setting the second lens.

5. The slit diffraction type hydrogen detection device according to claim 1, characterized in that, The preparation method of the diaphragm comprises the following steps: S1: Coating a photoresist coating on a substrate and setting a linear mask, and forming a linear mask imprint on the photoresist coating through photolithographic exposure; S2: After development processing, the linear photolithographic structure remains on the substrate, and a photolithographic straight line with a trapezoidal cross-section is formed after chloroform treatment; S3: Using a coating technology to deposit a layer of silicon oxide layer on the substrate, and then in-situ depositing a layer of palladium metal layer on the surface of the silicon oxide layer; S4: After removing the photoresist with a solvent and peeling off the substrate, a Pd / SiO2 double-layer film with a slit is obtained.

6. The slit diffraction type hydrogen detection device according to claim 5, wherein, The thickness of the photoresist coating is 2 - 5 μm, and the width of the linear mask is 0.6 - 1 μm.

7. The slit diffraction type hydrogen detection device according to claim 5, characterized in that, The coating technology is selected from radio frequency magnetron sputtering, pulsed laser deposition or electron beam evaporation.

8. The slit diffraction type hydrogen detection device according to claim 7, characterized in that, When the coating technology is radio frequency magnetron sputtering, the background vacuum is <10 -7 Pa, the deposition temperature is room temperature, the coating atmosphere is a mixed gas of argon and oxygen, the sputtering pressure is 10 - 200 Pa, and the radio frequency power is 20 - 300 W.

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