CN110887806A - Filtering-free sheet type infrared heat radiation gas concentration sensor based on metamaterial - Google Patents

Abstract

The invention provides a filterless infrared thermal radiation gas concentration sensor based on metamaterials, comprising a casing, a side wall, an anti-reflection film, a support frame, a detector chip, a circuit board, a thermal radiation chip, a heater, a temperature control Chip and pins; the casing is divided into a first air chamber and a second air chamber by an anti-reflection film arranged inside, the first air chamber is supported by the side walls arranged on both sides of the casing, and the casing enclosing the first air chamber is provided with An outer air hole, an inner air hole is arranged on the anti-reflection film, a support frame is arranged in the second air chamber, and one or more detector chips are arranged on the support frame, and a heat radiation chip is arranged on the opposite side of the detector chip, and the heat radiation chip is connected to the heater The heater is connected to the temperature control chip, the circuit board is arranged in the second air chamber, the circuit board is connected to the detector chip, the heat radiation chip, the temperature control chip and the pins, and the pins are arranged outside the casing. The invention adopts metamaterial, has high integration, low cost and wide application range.

Description

Filterless infrared thermal radiation gas concentration sensor based on metamaterial

technical field

The invention relates to the field of gas concentration monitoring, in particular to a filterless infrared thermal radiation gas concentration sensor based on metamaterials.

Background technique

With the improvement of people's living standards and the world's increasing attention to environmental protection, the monitoring of air pollution and industrial waste gas has gradually been paid more attention. Infrared gas measurement is a detection method with high sensitivity, good stability and wide applicability. It has been widely used in chemical industry, coal, metallurgy, electric power, etc. Among them, the non-dispersive infrared gas sensor is easy to integrate because of its simple structure. , stable performance and other advantages are favored. The current non-dispersive infrared sensor is usually composed of a broad-spectrum light source, a gas chamber and a detector with a filter. Although the filter ensures the measurement process, it reduces the integration of the device, and requires additional manufacturing and installation of filters and processing processes. Does not fit, increasing the industrial cost. The sensor without filter needs to be equipped with a specific narrow-spectrum light source for a certain gas, which is often more expensive and inconvenient.

Metamaterials or metasurfaces are materials modified by micro-nano processing, and their surfaces can be artificially etched with fixed patterns. Patterns at the micro- and nano-scale can significantly change the radiation characteristics of the material itself, and design the macro radiation characteristics according to human will under certain rules. Relying on the metamaterial design method, people can create infrared thermal radiation light sources, and design the magnitude of radiant energy in different wavelength bands under Planck's law. Taking the one-dimensional grating structure as an example, by designing the period and depth of the grating, the emissivity in a certain band can be achieved to be one. However, the thermal light source designed by metamaterials has low power and the emissivity varies greatly with the angle, so it is difficult to generate a strong signal for detection, which makes it difficult to apply to the detection of gas concentration, and the life of micro-nano processed products is relatively affected by the environment. large, the overall stability is tested.

The patent document with publication number CN1252462C discloses a gas concentration sensor using a nano-scale microporous structure optical fiber, and relates to a gas concentration sensor, especially a gas concentration sensor with a nano-scale micro-porous structure optical fiber. At least one light-emitting diode is provided, and the light path emitted by the light-emitting diode is provided with a self-focusing lens, and a glass fiber and a nano-fiber are respectively arranged in front of the self-focusing lens. One light enters the glass fiber through the lens, and the other light enters the nano fiber through the lens. The other ends of the two optical fibers are respectively connected to the detector, an optical filter is arranged in front of the photodetector, and the output end of the detector is connected to a gas concentration monitoring circuit through a differential amplifier. In this solution, the detector is provided with a filter. Although the filter ensures the measurement process, it reduces the integration of the device, and the filter that needs to be additionally manufactured and installed is not suitable for the processing process, which increases the industrial cost.

SUMMARY OF THE INVENTION

In view of the defects in the prior art, the purpose of the present invention is to provide a filterless infrared thermal radiation gas concentration sensor based on metamaterials.

A filterless infrared thermal radiation gas concentration sensor based on metamaterials provided by the present invention includes a casing, a side wall, an anti-reflection film, a support frame, a detector chip, a circuit board, a thermal radiation chip, a heater, a temperature control chip and pins;

The outer casing is divided into a first air chamber and a second air chamber by an anti-reflection film arranged inside, the first air chamber is supported by the side walls arranged on both sides of the outer casing, and an outer air hole is arranged on the outer casing surrounding the first air chamber, An inner air hole is arranged on the anti-reflection film, a support frame is arranged in the second air chamber, one or more detector chips are arranged on the support frame, a heat radiation chip is arranged opposite the detector chip, and the heat radiation chip is connected to a heater, and the heater The temperature control chip is connected, the circuit board is arranged in the second air chamber, the circuit board is connected with the detector chip, the heat radiation chip, the temperature control chip and the pins, and the pins are arranged outside the casing.

Preferably, the support frame and the housing are connected by a first sealing layer; the circuit board and the support frame are connected by a first sealing layer, and the circuit board and the housing are connected by a second sealing layer.

Preferably, the heater surface is covered with a first heat insulating layer except for the position of the heat radiation chip, and a second heat insulating layer, a temperature control chip and a third sealing layer are sequentially arranged between the heater and the casing from the inside to the outside.

Preferably, the positions of the outer air holes and the inner air holes are staggered from each other.

Preferably, the detector chip adopts a broad-spectrum photoelectric absorber, and the number of detector chips is two, which are respectively installed at positions of different elevation angles of the heat radiation chip.

Preferably, the distances between the two detector chips 10 and the heat radiation chips 17 are equal, and both are 5-10 mm.

Preferably, the signals of the heat radiation chip and the detector chip are processed by the signal amplification function circuit on the circuit board and then output by the pins, and the difference between the signals of the two detector chips can reflect the temperature of the heat radiation chip, and is used for Determine the emission power of the thermal radiation chip, and use the signal change of the detector chip perpendicular to the thermal radiation direction to determine the concentration of the gas to be measured.

Preferably, the heat radiation chip is a metal-dielectric-metal layered structure, including an anti-oxidation film layer, a metal two-dimensional array layer, a dielectric material layer, and a metal base layer; the heat radiation chip can make different elevation angles The emissivity of different wavelength bands is different in the inner chamber, which generates a distinguishable reference signal and a measurement signal, which reach different detector chips respectively after being attenuated by the gas in the second gas chamber.

Preferably, the unit of the metal two-dimensional array layer is a square with a side length of 300-500 nm, a period of 800-1300 nm, and any one or more of silver, copper and tungsten are used as materials.

Preferably, there are four pins, which are Vd pin, GND pin, TX pin and CX pin respectively, the Vd pin and GND pin are responsible for power supply, and the TX pin outputs the heat radiation chip temperature signal, the CX pin outputs the gas concentration signal to be measured.

Compared with the prior art, the present invention has the following beneficial effects:

1. The present invention uses the design of metamaterials, so that the dual-wavelength infrared detection technology can be realized under the premise of no filter, which not only realizes the concentration measurement of the gas to be measured, but also avoids the influence of heat source aging.

2. The structure of the present invention is simple and compact, and the filterless design greatly improves the integration of the gas sensor, and the wide-spectrum photodetector is cheaper than the narrow-spectrum photodetector, which also reduces the industrial cost of gas sensor manufacturing.

3. The present invention can realize gas detection of carbon dioxide and water vapor, has good stability and high precision, and can be applied to gas concentration detection in petrochemical industry, environmental monitoring and the like.

4. The power supply heating design of the present invention can be well matched with the modern electronic circuit system, and the application range is wider.

Description of drawings

Other features, objects and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments with reference to the following drawings:

FIG. 1 is a schematic cross-sectional structure diagram of the present invention.

FIG. 2 is a schematic diagram of the component composition structure of the present invention.

FIG. 3 is a schematic three-dimensional structure diagram of a periodic unit of a heat radiation chip of the present invention.

FIG. 4 is a schematic cross-sectional structural diagram of a periodic unit of the heat radiation chip of the present invention.

FIG. 5 is an emissivity spectrum diagram of the thermal radiation chip of the present invention.

The figure shows:

Side wall 1 Circuit board 11

The first air chamber 2 The second sealing layer 12

Anti-Reflection Coating 3 Pin 13

Inner air hole 4 Third sealing layer 14

Outer air hole 5 Temperature control chip 15

Shell 6 Second thermal insulation layer 16

First sealing layer 7 Heat radiation chip 17

Second air chamber 8 Heater 18

Support frame 9 First thermal insulation layer 19

Detector Chip 10

Detailed ways

The present invention will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that, for those skilled in the art, several changes and improvements can be made without departing from the inventive concept. These all belong to the protection scope of the present invention.

In the description of this application, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", The orientation or positional relationship indicated by "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, which is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying the indicated device. Or elements must have a particular orientation, be constructed and operate in a particular orientation, and therefore should not be construed as a limitation of the present application.

The invention provides a filterless infrared thermal radiation gas concentration sensor based on metamaterials, adopts a two-dimensional metal array structure and a dual-wavelength infrared monitoring principle, and is suitable for a gas concentration monitoring method and device in the infrared band. The present invention uses the manufacturing process of metamaterials to endow the heat radiation chip 17 with specific infrared heat radiation characteristics, so that the heat radiation chip 17 emits signals in different wavelength bands in different elevation angle intervals, so as to use only a broad-spectrum photodetector without using a filter. A light sheet that detects the target of a specific gas concentration. The distance between the two detector chips 10 and the thermal radiation chip 17 is about 5-10mm, and they are placed in different elevation angles to detect infrared signals of different wavelength bands. After these signals are calibrated, they can display the gas concentration information to be measured. The temperature information of the emission chip can also be displayed, which effectively ensures the accuracy and stability of the device. The power supply and heating system of the present invention can be encapsulated in components, has small volume, high precision, stability and reliability, and can be well adapted to modern electronic circuit systems.

According to the present invention, a filter-free infrared thermal radiation gas concentration sensor based on metamaterials, as shown in Figures 1-2, includes a housing 6, a side wall 1, an anti-reflection film 3, a support frame 9, a detector chip 10, The circuit board 11, the heat radiation chip 17, the heater 18, the temperature control chip 15 and the pins 13; the outer casing 6 is divided into the first air chamber 2 and the second air chamber 8 by the anti-reflection film 3 provided inside. The chamber 2 is supported by the side walls 1 provided on both sides of the housing 6, the housing 6 enclosing the first air chamber 2 is provided with an outer air hole 5, the anti-reflection film 3 is provided with an inner air hole 4, and the second air chamber 8 is provided with There is a support frame 9, one or more detector chips 10 are arranged on the support frame 9, a heat radiation chip 17 is arranged opposite the detector chip 10, the heat radiation chip 17 is connected to the heater 18, and the heater 18 is connected to the temperature control chip 15, The circuit board 11 is arranged in the second air chamber 8 , and the circuit board 11 is connected to the detector chip 10 , the heat radiation chip 17 , the temperature control chip 15 and the pins 13 , and the pins 13 are arranged outside the casing 6 . The support frame 9 and the housing are connected by the first sealing layer 7 ; the circuit board 11 and the supporting frame 9 are connected by the first sealing layer 7 , and the circuit board 11 and the housing 6 are connected by the second sealing layer 12 . The surface of the heater 18 is covered with a first heat insulation layer 19 at the position of the heat removal chip 17, and a second heat insulation layer 16, a temperature control chip 15 and a third seal are arranged between the heater 18 and the outer casing 6 from inside to outside. Layer 14. The positions of the outer air holes 5 and the inner air holes 4 are staggered from each other. There are four pins 13, which are Vd pin, GND pin, TX pin and CX pin respectively. The Vd pin and GND pin are responsible for power supply, and the TX pin outputs the temperature of the heat radiation chip 10. signal, the CX pin outputs the gas concentration signal to be measured. The anti-reflection film 3 weakens reflections in all directions to prevent the radiation signal after multiple reflections from interfering with the detection of the detector chip 10 . Preferably, the four walls of the second air chamber 8 are covered with the anti-reflection film 3 . Preferably, the heater 18 is a cermet heater.

The detector chip 10 adopts a broad-spectrum photoelectric absorber, and no filter is required. The number of detector chips 10 is two, which are respectively installed on the positions of the heat radiation chip 17 in different elevation directions. Preferably, the detector chips 10 One is installed on the support frame 9 at an elevation angle of 90 degrees of the heat radiation chip 17 , and the other is installed on the support frame 9 at an elevation angle of 60 degrees of the heat radiation chip 17 . The distances between the two detector chips 10 and the heat radiation chips 17 are equal, and both are 5-10 mm. The signals of the heat radiation chip 17 and the detector chip 10 are processed by the signal amplification function circuit on the circuit board 11 and then output by the pin 13. The difference between the signals of the two detector chips 10 can reflect the temperature of the heat radiation chip 17. , used to determine the emission power of the heat radiation chip 10, and use the signal change of the detector chip 10 perpendicular to the heat radiation direction to determine the gas concentration to be measured. The heat radiation chip 17 is a metal-dielectric-metal layered structure, including an anti-oxidation film layer, a metal two-dimensional array layer, a dielectric material layer, and a metal base layer; the heat radiation chip 17 can make different elevation angles. The emissivity of different wavelength bands is different, and a reference signal and a measurement signal that can be distinguished are generated, which respectively reach different detector chips 10 through the attenuation of the gas in the second gas chamber 8 . The unit of the metal two-dimensional array layer is a square with a side length of 300-500 nm, a period of 800-1300 nm, and any one or more of silver, copper and tungsten are used as materials. The geometrical parameters of the metal 2D array layer are influenced by the metal material used. The dielectric material layer is made of large refractive index materials such as silicon and aluminum oxide, and the thickness is about 100 nm.

The signals of the two detector chips 10 of the present invention can display both the concentration information of the gas to be measured and the temperature information of the heat radiation chip 17 . In the second gas chamber 8, different gases have absorption coefficients that vary with concentration in a specific wavelength band, and the decay process follows the Beer-Lambert law. For the heat radiation chip 17 designed for the gas to be measured, the signals of its emission signals at different angles include both strong absorption bands and non-absorbing bands. In particular, there is only a strong absorption band in the 90-degree elevation direction. The elevation area within ten degrees has both strong absorption bands and non-absorbing bands. The selection of these two bands should also take into account the influence of other gases, and should avoid the absorption of irrelevant gases.

The heat radiation chip 17 in the present invention has a strong absorption band in a wide range of angles, especially at an elevation angle other than 20 degrees, the emissivity of the strong absorption band is almost unchanged and kept at about 0.9, while the non-absorbing band only has a strong absorption band. It only appears in small elevation angles, especially in elevation angles within 60 degrees, and the non-absorbing band gradually increases and reaches about 0.6. The strong absorption band signal reflects the concentration of the internal gas, and the non-absorbing band signal reflects the temperature fluctuation of the heat radiation chip 17 . Therefore, when the distances between the two detector chips 10 and the thermal radiation chip 17 are equal, the difference between the signals of the two detector chips can reflect the temperature fluctuation of the thermal radiation chip, and the readings of the detector chips used to correct the large elevation angle reflect the gas to be measured in the gas chamber. concentration changes.

The present invention adopts the heat radiation and filterless method to improve the integration degree, but the lower power of heat radiation puts forward higher requirements for signal detection. The temperature of the heat radiation chip in the present invention is set at about 400-500 degrees to improve the Planck limit, and the integrated signal filtering and amplifying functional circuit helps reduce noise.

In addition, the use of the high-temperature thermal radiation chip will cause the pressure and temperature inside the device to change, and the output signal of the detector chip 10 will fluctuate at different temperatures, resulting in measurement errors. However, in the present invention, the temperature of the detector chip 10 is mainly affected by the temperature of the thermal radiation chip 17. The influence of the temperature of the heat radiation chip 17 can be included in the prediction model in the calibration stage, so that it is not necessary to introduce a temperature compensation mechanism. The specific steps are as follows: first, the temperature is calibrated in an environment filled with non-absorbing gas, and the corresponding relationship between the temperature of the thermal radiation chip 17 and the difference between the signals of the two detector chips 10 is established. Corresponding relationship 2 of the 10 signal, and then filling the absorbing sample gas to establish the corresponding relationship 3 between the signal of the detector chip 10 with a large elevation angle and the concentration of the absorbing gas at a standard temperature (eg, 700K). In the actual measurement, firstly use the corresponding relationship 1 and 2 to obtain the temperature of the thermal radiation chip 17 and the signal of the detector chip 10 with a large elevation angle, and then query the corresponding relationship 3 to obtain the real absorbing gas concentration according to the change ratio of the radiation force of the strong absorption band under blackbody radiation. .

Preferred embodiment:

Set the gas to be measured as carbon dioxide gas. The technical scheme of the present invention is to design a metamaterial infrared thermal radiation gas concentration sensor, that is, a filterless infrared thermal radiation gas concentration sensor based on metamaterials, comprising: an anti-reflection film 3 with an inner air hole 4 to cover the outer shell 6 Divided into two parts, the first air chamber 2 is surrounded by the side wall 1 for the free diffusion of outside air through the outer air hole 5, and the second air chamber 8 is used as a working area. The inner air hole 4 and the outer air hole 5 are mutually staggered. The detector chip 10 is fixed on the support frame 9 and then sealed by the sealing layer I7. The heat radiation chip 17 is placed on the heater 18 , and covers the front and rear of the first heat insulating layer 19 and the second heat insulating layer 16 , and only the heat radiation chip 17 is exposed at the front. After the first heat insulation layer 19 is a temperature control chip 15 for monitoring the temperature of the components at all times, and is separated from the casing 6 by a third sealing layer 14 . The circuit board 11 is placed under the first sealing layer 7 and is separated from the housing 6 by the second sealing layer 12 . There are four pins 13, which are Vd, GND, TX, CX, respectively. Vd and GND are responsible for the power supply of the device. TX outputs the temperature signal of the heat radiation chip 17, and CX outputs the gas concentration signal to be measured.

The heat radiation chip 17 is bonded to the top of the heater 18 as the core of the whole device, and the gap is coated with thermally conductive glue. The heat radiation chip 14 mainly has four layers: an anti-oxidation film layer, a metal two-dimensional array layer, a dielectric material layer, and a metal base layer. The anti-oxidation layer is a dense aluminum oxide film of about 10nm-20nm, which is used to isolate the air to protect the metal array. In the next metal two-dimensional array layer, a rectangular tungsten unit is selected. The high melting point of tungsten can avoid damage caused by metal creep at high temperature for a long time. The side length of the unit is 420nm, the period is 1050nm, and the thickness is 80nm. Silicon is selected as the material for the dielectric material layer. The larger refractive index of silicon can effectively reduce the size of the device and improve the emissivity of the target wavelength band, and its thickness is 120 nm. The metal base layer is made of copper, which can reduce the interference in the high frequency band. The designed metamaterial thermal radiation chip maintains a high emissivity of about 0.9 at an elevation angle of 4.2um and 20 degrees, and maintains a gradually rising emissivity at an elevation angle of 2.4um and 60 degrees. The emissivity of the remaining low-frequency bands is 0.1-0.3, and the high-frequency bands have little influence on detection due to the limitation of Planck's black-body radiation law.

In the second gas chamber 8, different gases have absorption coefficients that vary with concentration in a specific wavelength band, and the decay process follows the Beer-Lambert law. Carbon dioxide has a strong absorption peak at about 4.2um, but almost no absorption at 2.4um, and the interference of irrelevant gases in the atmosphere such as water, oxygen, nitrogen, etc. on these two bands is very small. The higher the concentration of carbon dioxide gas, the more obvious the signal attenuation, and the signal strength of the non-absorbing band does not change. However, the heat source may produce temperature fluctuations during operation, and the signal in the non-absorbing band can be used to monitor the working temperature of the heat source, making the gas concentration measurement more accurate.

The detector chip 10 uses a wide-spectrum photodetector, such as a thermopile detector without a filter, which is bonded to the support frame 9, and its detection range should cover 2um-5um, and the absorption rate should not change greatly. One detector chip 10 is placed directly above the heat radiation chip 17 (at an elevation angle of 90 degrees), and the other detector chip 10 is placed obliquely above the heat radiation chip 17 (about an elevation angle of 60 degrees), both facing the heat radiation chip and at an equal distance from it. . Since the distances between the two detector chips 10 and the thermal radiation chip 17 are equal, and the positions of the strong absorption band and the non-absorption band hardly change with the angle, the difference between the signals of the two detector chips 10 reflects the energy of the non-absorption band, which in turn reflects The temperature of the thermal radiation chip 17 fluctuates, and the indication of the detector chip 10 with a large elevation angle changes with the concentration of the gas to be measured.

The anti-reflection film 3 divides the device into two air chambers, which weakens the reflection in each direction and prevents the radiation signal after multiple reflections from interfering with the detector chip 10 . In order to improve the detection accuracy, the temperature of the heat radiation chip 17 in the present invention is set at about 400-500 degrees to improve the Planck limit, and the function circuit of signal filtering and amplifying is integrated to output the signal.

In addition, the use of the high-temperature thermal radiation chip will cause the pressure and temperature inside the device to change, and the output signal of the detector chip 10 will fluctuate at different temperatures, resulting in measurement errors. However, in the present invention, the temperature of the detector chip 10 is mainly affected by the temperature of the thermal radiation chip 17. influence, and the influence of the temperature of the heat radiation chip 17 can be included in the prediction model in the calibration stage. Firstly, the temperature is calibrated in an environment filled with non-absorbing gas, and the corresponding relationship between the temperature of the thermal radiation chip 17 and the difference between the signals of the two detector chips 10 is established. Relation 2, and then fill in absorbing sample gas to establish a corresponding relationship 3 between the signal of the detector chip 10 with a large elevation angle and the concentration of absorbing gas at a standard temperature (eg, 700K). In the actual measurement, firstly use the corresponding relationship 1 and 2 to obtain the temperature of the thermal radiation chip 17 and the signal of the large elevation angle detector chip 10, and then query the corresponding relationship 3 to obtain the real absorbing gas concentration according to the change ratio of the strong absorption band radiation force under blackbody radiation.

Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the above-mentioned specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essential content of the present invention. The embodiments of the present application and features in the embodiments may be combined with each other arbitrarily, provided that there is no conflict.

Claims (10)

1. A filter-free sheet type infrared thermal radiation gas concentration sensor based on metamaterials is characterized by comprising a shell (6), a side wall (1), an antireflection film (3), a support frame (9), a detector chip (10), a circuit board (11), a thermal radiation chip (17), a heater (18), a temperature control chip (15) and pins (13);

the shell (6) is divided into a first air chamber (2) and a second air chamber (8) by an antireflection film (3) arranged inside, the first air chamber (2) is supported by side walls (1) arranged on two sides in the shell (6), an outer air hole (5) is formed in the shell (6) enclosing the first air chamber (2), an inner air hole (4) is formed in the antireflection film (3), a support frame (9) is arranged in the second air chamber (8), one or more detector chips (10) are arranged on the support frame (9), heat radiation chips (17) are arranged opposite to the detector chips (10), the heat radiation chips (17) are connected with a heater (18), the heater (18) is connected with a temperature control chip (15), a circuit board (11) is arranged in the second air chamber (8), the circuit board (11) is connected with the detector chips (10), the heat radiation chips (17), the temperature control chip (15) and pins (13), the pins (13) are arranged outside the housing (6).

2. The metamaterial-based filter-less sheet-type infrared thermal radiation gas concentration sensor as claimed in claim 1, wherein the support frame (9) is connected with the housing through a first sealing layer (7); the circuit board (11) is connected with the support frame (9) through the first sealing layer (7), and the circuit board (11) is connected with the shell (6) through the second sealing layer (12).

3. The metamaterial-based filter-less sheet-type infrared thermal radiation gas concentration sensor as claimed in claim 1, wherein the position of the heat radiation removing chip (17) on the surface of the heater (18) is covered with a first thermal insulation layer (19), and a second thermal insulation layer (16), a temperature control chip (15) and a third sealing layer (14) are sequentially arranged between the heater (18) and the housing (6) from inside to outside.

4. The metamaterial-based filter-less sheet-type infrared thermal radiation gas concentration sensor as claimed in claim 1, wherein the outer air holes (5) and the inner air holes (4) are staggered in position.

5. The metamaterial-based filter-less sheet-type infrared thermal radiation gas concentration sensor as claimed in claim 1, wherein the detector chips (10) employ a wide-spectrum photoelectric absorber, and the number of the detector chips (10) is two, and the two detector chips are respectively mounted on the positions of the thermal radiation chips (17) in different elevation directions.

6. The metamaterial-based filter-less sheet-type infrared thermal radiation gas concentration sensor as claimed in claim 5, wherein the two detector chips (10) are equidistant from the thermal radiation chip (17) and are each 5-10 mm.

7. The metamaterial-based filter-less sheet-type infrared thermal radiation gas concentration sensor as claimed in claim 5, wherein the signals of the thermal radiation chip (17) and the detector chip (10) are processed by a signal amplification function circuit on the circuit board (11) and then output by the pin (13), and the difference between the signals of the two detector chips (10) can reflect the temperature condition of the thermal radiation chip (17) to determine the emission power of the thermal radiation chip (10), and the concentration of the gas to be measured is determined by the signal change of the detector chip (10) perpendicular to the thermal radiation direction.

8. The metamaterial-based filter-less sheet-type infrared thermal radiation gas concentration sensor as claimed in claim 1, wherein the thermal radiation chip (17) is a metal-dielectric-metal layered structure comprising an oxidation prevention film layer, a metal two-dimensional array layer, a dielectric material layer, a metal substrate layer; the heat radiation chip (17) can enable the emissivity of different wave bands in different elevation angles to be different, generate a reference signal and a measurement signal which can be distinguished, and the reference signal and the measurement signal respectively reach different detector chips (10) through the attenuation of gas in the second gas chamber (8).

9. The filter-less sheet type infrared thermal radiation gas concentration sensor based on metamaterial according to claim 8, wherein the unit of the metal two-dimensional array layer is a square with a side length of 300-500nm and a period of 800-1300nm, and the material is any one or more of silver, copper and tungsten.

10. The metamaterial-based filter-free sheet type infrared thermal radiation gas concentration sensor as claimed in claim 1, wherein the number of the pins (13) is four, and the pins are respectively a Vd pin, a GND pin, a TX pin and a CX pin, the Vd pin and the GND pin are responsible for power supply, the TX pin outputs a temperature signal of the thermal radiation chip (10), and the CX pin outputs a gas concentration signal to be measured.

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