Novel cavity based on silicon substrate and infrared gas sensor

Abstract

The novel cavity based on the silicon substrate comprises a V-shaped optical channel etched on the silicon substrate, the V-shaped optical channel is formed by communicating one ends of two sub-grooves, a light source off-axis paraboloid is arranged on one sub-groove far away from the communicating end, and the other sub-groove far away from the communicating end is provided with a light source off-axis paraboloid. The other branch groove is provided with a detector off-axis paraboloid far away from the communicating end, a reflecting surface is etched at the communicating position of the two branch grooves, and the V-shaped optical channel is communicated with the air hole. Through the V-shaped optical channel, the reflection times of an optical path are reduced, the processing steps are effectively simplified, and meanwhile, the attenuation of light after multiple times of reflection is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of gas sensors, in particular to a new silicon-based cavity and an infrared gas sensor. Background Art

[0002] Infrared gas sensors utilize the absorption characteristics of specific gases to light of specific wavelengths, and measure and derive the concentration of the gas on site based on the Lambert-Beer absorption law. They have the advantages of good selectivity, long life, and high reliability. They are widely used in petroleum, chemical industry, metallurgy, electric power, air quality detection, pollution source monitoring, industrial process gas analysis and other fields.

[0003] In the patent document "An Infrared Gas Sensor Based on Silicon-Based Multiple Reflection Cavity" (publication number: CN113484267B) disclosed by China on July 29, 2022, the patent technical solution is described as including: a silicon-based multiple reflection cavity, an infrared light source, a light detection module and an integrated circuit module; the multiple reflection cavity includes an upper silicon wafer, a lower silicon wafer, an off-axis parabola, a silicon-based reflector and a filter; a groove is etched on the lower surface of the upper silicon wafer, and silicon-based reflectors are provided on both sides of the upper silicon wafer, and the surface of the silicon-based reflector is coated with a reflective film to form an optical path channel; the lower silicon wafer and the upper silicon wafer are stacked together; off-axis paraboloids are installed at both ends of the optical path channel, and an input hole and an output hole are respectively provided on the lower silicon wafer; the infrared light source and the light detection module are respectively provided at the input hole and the output hole; an air hole is provided on the upper silicon wafer, and a waterproof and breathable membrane is provided on the outside. However, this technical solution has too many light path reflections, resulting in light attenuation, and the silicon-based reflective sheet needs to be coated before it can be formed, which has many processing steps and increases the difficulty of production. Utility Model Content

[0004] In view of the deficiencies in the above-mentioned background technology, the present invention proposes a new silicon-based cavity, which solves the problem of excessive light path reflection in the prior art.

[0005] The technical solution of a new silicon-based cavity of the utility model is realized as follows: the V-shaped light channel etched on the silicon substrate, the V-shaped light channel is formed by connecting one end of two branch grooves, and one of the branch grooves is provided with an off-axis parabola of a light source away from the connecting end, and the other branch groove is provided with an off-axis parabola of a detector away from the connecting end, a reflecting surface is etched at the connecting point of the two branch grooves, and the V-shaped light channel is connected to the air vent.

[0006] Preferably, the reflecting surface is an off-axis parabola.

[0007] Preferably, the curvature of the reflecting surface is different from that of the off-axis parabola of the light source and the off-axis parabola of the detector.

[0008] In order to solve the above problems, the present invention also proposes an infrared gas sensor using the above-mentioned new silicon-based cavity.

[0009] The technical solution of another infrared gas sensor of the present invention is implemented as follows: it includes: an upper silicon wafer, a lower silicon wafer and a circuit board, the upper silicon wafer is provided with the aforementioned new silicon-based cavity, the lower silicon wafer is provided with a light input hole and a light output hole, the circuit board is provided with an infrared light source corresponding to the light input hole, and the circuit board is also provided with a light detection module corresponding to the light output hole.

[0010] Preferably, the infrared light source faces the off-axis parabola.

[0011] Preferably, the light detection module faces the off-axis parabola of the detector.

[0012] Preferably, a processing control module is provided on the circuit board, and the processing control module is connected to the infrared light source and the light detection module respectively.

[0013] Preferably, the infrared light source is a MEMS infrared light source or an LED light source.

[0014] Preferably, the light detection module is a thermopile or a pyroelectric sensor.

[0015] Preferably, the circuit board is a ceramic circuit board.

[0016] This new design reduces the number of light reflections through a V-shaped optical channel, effectively simplifying the processing steps and reducing light attenuation after multiple reflections. Furthermore, the etched reflective surface is an off-axis parabola, eliminating the need for surface coating. This further simplifies the processing steps, reduces production costs, and significantly improves light transmission efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 This is a three-dimensional diagram of a new silicon-based cavity of the utility model;

[0019] Figure 2 This is a schematic diagram of the explosion of the infrared gas sensor of the utility model;

[0020] Figure 3 This is a cross-sectional view of the infrared gas sensor of the present invention.

[0021] In the figure: 1. Circuit board; 2. Lower silicon wafer; 3. Upper silicon wafer; 4. Air vent; 5. Light input hole; 6. Light output hole; 7. Infrared light source; 8. Light detection module; 9. Light source off-axis parabola; 10. Detector off-axis parabola; 11. Reflection surface. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] like Figure 1 The utility model shows a novel silicon-based cavity comprising a V-shaped optical channel etched into a silicon substrate. The V-shaped optical channel is formed by connecting two slots at one end. One of the slots, away from the connecting end, is provided with an off-axis parabola 9 for the light source, and the other slot, away from the connecting end, is provided with an off-axis parabola 10 for the detector. A reflective surface 11 is etched at the connecting point between the two slots. The reflective surface 11 is an off-axis parabola. The V-shaped optical channel is connected to the air vent 4. The curvature of the reflective surface 11 is different from that of the off-axis parabola 9 for the light source and the off-axis parabola 10 for the detector. Both the off-axis parabola 9 for the light source and the off-axis parabola 10 for the detector are 45° off-axis, with a focal length 2-3 times the optical length of the V-shaped optical path.

[0024] like Figure 2 and Figure 3 The infrared gas sensor of the present invention shown in FIG. 1 includes an upper silicon wafer 3, a lower silicon wafer 2, and a circuit board 1. The upper silicon wafer 3 is provided with a novel silicon-based cavity according to the aforementioned embodiment. The lower silicon wafer 2 is provided with a light entry hole 5 and a light exit hole 6. The circuit board 1 is provided with an infrared light source 7 corresponding to the light entry hole 5. The circuit board 1 is also provided with a light detection module 8 corresponding to the light exit hole 6. The infrared light source 7 faces an off-axis parabola 9, and the light detection module 8 faces an off-axis parabola 10. The circuit board 1 is provided with a processing and control module, which is connected to the infrared light source 7 and the light detection module 8. The processing and control module is an MCU. The infrared light source 7 is a MEMS infrared light source or an LED light source. The light detection module 8 is a thermopile or a pyroelectric sensor. The circuit board 1 is a ceramic circuit board. The processing and control module both controls the operation of the infrared light source 7 and detects the infrared spectral data collected by the light detection module 8.

[0025] When the utility model is in operation, the gas to be measured enters the V-shaped light channel through the air vent, and the processing and control module controls the infrared light source to generate infrared light. When the infrared light passes through the V-shaped light channel, if the gas to be measured is present, the infrared light of the corresponding wavelength will be absorbed. After detecting the infrared light, the light detection module calculates the concentration of the gas to be measured by comparing the amount of light intensity absorbed with the preset parameters of the gas to be detected through the processing and control module.

[0026] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A new silicon-based cavity, characterized in that: include: A V-shaped optical channel is etched on a silicon substrate. The V-shaped optical channel is formed by connecting one end of two sub-grooves, and one of the sub-grooves is provided with a light source off-axis parabola (9) away from the connecting end, and the other sub-groove is provided with a detector off-axis parabola (10) away from the connecting end. A reflecting surface (11) is etched at the connecting portion of the two sub-grooves, and the V-shaped optical channel is connected to the air vent (4).

2. The novel silicon-based cavity according to claim 1, characterized in that: The reflecting surface (11) is an off-axis parabola.

3. The novel silicon-based cavity according to claim 2, characterized in that: The curvature of the reflecting surface (11) is different from that of the light source off-axis parabola (9) and the detector off-axis parabola (10).

4. An infrared gas sensor, characterized in that: include: An upper silicon wafer (3), a lower silicon wafer (2) and a circuit board (1), wherein the upper silicon wafer (3) is provided with a novel silicon-based cavity according to any one of claims 1 to 3, the lower silicon wafer (2) is provided with a light input hole (5) and a light output hole (6), respectively, the circuit board (1) is provided with an infrared light source (7) corresponding to the light input hole (5), and the circuit board (1) is also provided with a light detection module (8) corresponding to the light output hole (6).

5. The infrared gas sensor according to claim 4, characterized in that: The infrared light source (7) faces the light source off-axis parabola (9).

6. The infrared gas sensor according to claim 4 or 5, characterized in that: The optical detection module (8) faces the detector off-axis parabola (10).

7. The infrared gas sensor according to claim 6, characterized in that: A processing control module is provided on the circuit board (1), and the processing control module is respectively connected to the infrared light source (7) and the light detection module (8).

8. The infrared gas sensor according to claim 7, characterized in that: The infrared light source (7) is a MEMS infrared light source or an LED light source.

9. The infrared gas sensor according to claim 8, characterized in that: The light detection module (8) is a thermopile or a pyroelectric sensor.

10. The infrared gas sensor according to any one of claims 7 to 9, characterized in that: The circuit board (1) is a ceramic circuit board.

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