A linearity optimization test method for semiconductor gas sensors

Abstract

The present invention discloses a linearity optimization test method for a semiconductor gas sensor, belonging to the technical field of gas detection. Specifically, it includes: obtaining the working temperature range [A, B] when the linearity of the sensor is greater than the set standard, and setting several test temperatures in the test environment to collect the internal temperature of the sensor in real time. For each test temperature, if it is less than A, control the adjustable voltage output circuit to heat the sensor; if it is greater than B, control the adjustable voltage output circuit to cool the sensor. At any test temperature, plot the curve of the internal temperature of the sensor changing with time, and calculate the temperature change rate corresponding to this test temperature; then calculate the corresponding balanced working voltage according to the temperature change rate, and use it as the working voltage of the adjustable voltage output circuit at this test temperature. The present invention realizes the targeted optimization of the gas sensor in different scenarios.

Description

Technical Field

[0001] The present invention relates to the technical field of gas detection, and particularly to a linearity optimization test method for a semiconductor gas sensor. Background Art

[0002] A semiconductor gas sensor is a device that can convert gas concentration into an electrical signal output, and is widely used in fields such as environmental monitoring, industrial production, and home health. However, due to the working characteristics of the gas sensor being affected by various factors such as temperature, air pressure, and humidity, its performance often exhibits a certain degree of non-linearity, which brings certain difficulties to the accurate measurement of gas concentration.

[0003] In order to improve the measurement accuracy of semiconductor gas sensors, calibration methods are mainly used in the prior art to optimize the linearity of the sensors. In the article "Research on the Influence of Dynamic Heating Voltage on the Linearity of SnO 2 Gas Sensors", the influence of four different dynamic heating voltages, namely 3 - 5V sine wave, square wave, FM frequency modulation wave, and AM amplitude modulation wave, on the linearity of SnO 2 gas sensors was studied through experiments. The experimental results show that compared with the static heating method, the use of periodic dynamic heating voltage can effectively improve the linearity of SnO 2 gas sensors. Compared with sine waves and square waves, the sensor can obtain better linearity under the action of FM frequency modulation waves and AM amplitude modulation waves, and the effect is the best under the action of FM frequency modulation waves.

[0004] However, in the actual application of semiconductor gas sensors, due to the large differences in environmental temperature changes in different application scenarios and seasons, the temperature will not remain constant. Therefore, a fixed heating voltage cannot meet the heating requirements of the sensor, and it is necessary to adjust the heating temperature according to the change of environmental temperature, so that the working temperature of the semiconductor gas sensor always remains within a suitable range, thereby ensuring the stability of the sensor linearity. Summary of the Invention

[0005] The purpose of the present invention is to provide a linearity optimization test method for a semiconductor gas sensor to solve the following technical problems:

[0006] In the actual application of semiconductor gas sensors, due to the large differences in environmental temperature changes in different application scenarios and seasons, the temperature will not remain constant. Therefore, a fixed heating voltage cannot meet the heating requirements of the sensor, and it is necessary to adjust the heating temperature according to the change of environmental temperature, so that the working temperature of the semiconductor gas sensor always remains within a suitable range, thereby ensuring the stability of the sensor linearity.

[0007] The purpose of the present invention can be achieved through the following technical solutions:

[0008] A linearity optimization test method for a semiconductor gas sensor includes the following steps:

[0009] Obtain the working temperature range [A, B] when the linearity of the sensor is greater than the set standard, set n test temperatures T, where n is a preset value, and the test temperatures are not within the working temperature range. At any test temperature, the internal temperature t of the sensor is collected in real time;

[0010] For the i-th test temperature T i , where i ∈ [1, n], if the test temperature is less than the interval temperature A, control the adjustable voltage output circuit to heat the sensor. When the internal temperature t reaches A, suspend heating, wait for a set duration, and then continue to heat the sensor. When the internal temperature reaches B, stop heating;

[0011] If the test temperature is greater than B, control the adjustable voltage output circuit to cool the sensor. When the internal temperature t reaches B, suspend cooling, wait for a set duration, and then continue to cool the sensor. When the internal temperature reaches A, stop cooling;

[0012] Draw a curve of the internal temperature of the sensor changing with time, and respectively obtain the slopes k 1 and k 2 when the internal temperature t passes through the A coordinate point and the B coordinate point, convert the slopes into the corresponding temperature change rates v 1 and v 2 , and calculate the balanced working voltage U 1 and U 2 of the adjustable voltage output circuit according to the temperature change rates. The calculation formulas are:

[0013] ; ;

[0014] where the unit of the temperature change rate is Kelvin per second, ω is a preset correction coefficient, c is the specific heat capacity of the semiconductor material, m is the mass of the semiconductor material, and R is the resistance value of the semiconductor material at the current temperature; then for the i-th test temperature T i , when the test temperature is less than the interval temperature A, the working voltage range of the adjustable voltage output circuit is [U 1 , U 2 ; when the test temperature is greater than the interval temperature B, the working voltage range of the adjustable voltage output circuit is [U 2 , U 1 .

[0015] As a further solution of the present invention: The process of obtaining the slope is:

[0016] Mark the time coordinates when the internal temperature of the sensor is A or B. After the adjustable voltage output circuit pauses heating or cooling, monitor the curve of the internal temperature t of the sensor changing with time. When the internal temperature of the sensor reaches A - a or B - b, where a and b are the test temperature thresholds, obtain the time coordinates at this time, and mark the slope of the line connecting the A coordinate point and the A - a coordinate point as k 1 Mark the slope of the line connecting the B coordinate point and the B - b coordinate point as k 2 .

[0017] As a further solution of the present invention: at any test temperature, evenly divide the working temperature range [A, B] into N temperature sub - ranges, where N is a preset value, and evenly divide the working voltage range of the corresponding adjustable voltage output circuit into N voltage sub - ranges in the same way. The temperature sub - ranges and the voltage sub - ranges correspond to each other in sequence. When the internal temperature of the semiconductor is in any temperature sub - range, set the working voltage of the adjustable voltage output circuit to the corresponding voltage sub - range

[0018] As a further solution of the present invention: set N second test temperatures, which correspond to the humidity sub - ranges one by one. Whenever the second test temperature changes, the working voltage of the corresponding adjustable voltage output circuit is also adjusted to the corresponding voltage sub - range, and the index of the test gas sample is also adjusted accordingly; record the output gas indexes collected by the sensor at different second test temperatures, and calculate the linearity R of the semiconductor sensor based on the actual gas indexes 2 , the formula is:

[0019] ;

[0020] where y i is the output gas index corresponding to any second test temperature, is the average value of the actual gas indexes, is the actual gas index corresponding to any second test temperature. When the calculated linearity of the sensor is lower than the set standard, reduce the test temperature threshold and test again

[0021] As a further solution of the present invention: when the test temperature is within [A, B], do not collect the internal temperature of the semiconductor, and the adjustable voltage output circuit stops working

[0022] As a further solution of the present invention: the selection method of the n test temperatures is as follows:

[0023] On both sides of the working temperature range [A, B], select several test temperatures at fixed intervals respectively, and the number of test temperatures on both sides is equal

[0024] As a further solution of the present invention: the internal temperature of the semiconductor is collected based on the internal temperature sensor of the STM32 chip. The sensor integrates an ADC, reads the voltage value of the internal temperature sensor through the ADC, and converts it into temperature through a formula.

[0025] As a further solution of the present invention: the adjustable voltage output circuit adjusts the power of the heater based on the microprocessor and the digital potentiometer to heat the sensor; in the adjustable voltage output circuit, the sensor is cooled by adjusting the reference voltage or the resistance value in the feedback loop.

[0026] As a further solution of the present invention: the waveform of the working voltage of the adjustable voltage output circuit is an FM amplitude-modulated wave.

[0027] Advantages of the present invention:

[0028] In the present invention, by placing the sensor in different test temperatures and adjusting the adjustable voltage output circuit to change the internal temperature of the sensor, when the internal temperature of the sensor passes through the upper and lower limits of the working temperature range, the heat transfer speed at this time is recorded by pausing, so as to obtain the environmental temperature at this time and the heat transfer speed on the surface of the sensor, and then calculate the working voltage of the adjustable voltage output circuit according to the heat transfer speed, so that the semiconductor sensor can always be in an appropriate working temperature range regardless of the usage scenario, and through cyclic testing, the measurement accuracy and stability of the sensor are gradually improved, realizing the adaptability and versatility of the sensor in different application scenarios. Description of the drawings

[0029] The present invention will be further described below with reference to the drawings.

[0030] Figure 1 is a schematic flow chart of the present invention. Specific embodiments

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0032] Please refer to Figure 1 As shown, the present invention is a linearity optimization test method for a semiconductor gas sensor, including the following steps:

[0033] I. Selection of test temperature and setting of internal temperature acquisition rules:

[0034] Determination of the operating temperature range: First, it is necessary to obtain the operating temperature range in which the linearity of the sensor is greater than the set standard, denoted as [A, B]. This range is the temperature range within which the sensor can maintain good linearity under normal operating conditions, which is crucial for ensuring the accuracy and reliability of the sensor output signal.

[0035] Test temperature setting: On both sides of the operating temperature range [A, B], a number of test temperatures are selected at fixed intervals, and the number of test temperatures on both sides is equal, with a total of n test temperatures set, where n is a preset value. These test temperatures are not within the operating temperature range, aiming to simulate the performance of the sensor when it is outside the normal operating temperature range, so as to better optimize its linearity.

[0036] Internal temperature acquisition conditions: At any test temperature, the internal temperature t of the sensor is acquired in real time. However, when the ambient temperature is within the operating temperature range [A, B], the internal temperature of the semiconductor is not acquired, and at this time, the adjustable voltage output circuit stops working. This is because within this temperature range, the sensor itself can maintain good linearity and does not require additional temperature control and voltage adjustment.

[0037] II. Temperature control operation process:

[0038] For each test temperature T i , different temperature control strategies are adopted according to its relationship with the operating temperature range:

[0039] Heating control: If the test temperature T i is less than the range temperature A, it indicates that the ambient temperature where the sensor is currently located is relatively low and needs to be heated. The specific operation is to control the adjustable voltage output circuit to heat the sensor. When the internal temperature t reaches A, the heating is paused, and after waiting for a set duration, the sensor is heated again until the internal temperature reaches B, at which point the heating stops. This can ensure that the internal temperature of the sensor can be stably heated from a state lower than A to B, simulating the process of starting up and warming up to the normal operating temperature range in a low-temperature environment.

[0040] Cooling control: If the test temperature T i is greater than the range temperature B, it indicates that the ambient temperature where the sensor is located is too high and needs to be cooled. The operation method is to control the adjustable voltage output circuit to cool the sensor. When the internal temperature t reaches B, the cooling is paused, and after waiting for a set duration, the sensor is cooled again until the internal temperature reaches A, at which point the cooling stops. This process is to examine how the sensor reaches the normal operating temperature range by cooling in a high-temperature environment and the change of its linearity during this process.

[0041] III. Curve plotting and voltage calculation method:

[0042] Curve plotting: During the entire temperature control process, plot the curve of the internal temperature of the sensor changing with time. This curve can intuitively reflect how the internal temperature of the sensor rises or falls with time at different test temperatures, as well as the temperature change trend when reaching the boundary of the working temperature range.

[0043] Slope acquisition: Mark the time coordinates when the internal temperature of the sensor is A or B. After the adjustable voltage output circuit pauses heating or cooling, monitor the curve of the internal temperature t of the sensor changing with time. When the internal temperature of the sensor reaches A - a or B - b, where a and b are test temperature thresholds, obtain the time coordinates at this time, and mark the slope of the line connecting the A coordinate point and the A - a coordinate point as k 1 and mark the slope of the line connecting the B coordinate point and the B - b coordinate point as k 2 .

[0044] Temperature change rate and voltage calculation: Obtain the corresponding temperature change rate v according to the slope 1 and v 2 . After obtaining the temperature change rate, the balanced working voltages U1 and U2 of the adjustable voltage output circuit can be calculated according to the following calculation formula:

[0045] ; ;

[0046] where the unit of the temperature change rate is Kelvin per second, ω is a preset correction coefficient (used to fine - tune the calculation result according to the actual situation to be closer to the actual working scenario), c is the specific heat capacity of the semiconductor material, m is the mass of the semiconductor material, and R is the resistance value of the semiconductor material at the current temperature. These parameters together determine the voltage magnitude that the adjustable voltage output circuit should output under different temperature change conditions so that the internal temperature of the sensor can change stably as expected.

[0047] Determination of the working voltage range: For the i - th test temperature T i , determine the working voltage range of the adjustable voltage output circuit according to its relationship with the working temperature range. When the test temperature is less than the interval temperature A, the working voltage range of the adjustable voltage output circuit is [U1, U2]; when the test temperature is greater than the interval temperature B, the working voltage range of the adjustable voltage output circuit is [U2, U1]. In this way, according to different test temperature scenarios, the voltage output range of the adjustable voltage output circuit can be precisely adjusted, thereby optimizing the linearity of the sensor so that it can maintain good measurement performance under various environmental temperatures.

[0048] In the method for optimizing the linearity of the semiconductor gas sensor of the present invention, in order to more precisely control the internal temperature of the sensor, and then accurately adjust the operating voltage of the adjustable voltage output circuit to optimize the linearity of the sensor, the following advanced zoning control strategy is adopted:

[0049] I. Division of temperature sub-intervals and voltage sub-intervals:

[0050] 1. Division of temperature sub-intervals: At any test temperature, the operating temperature range [A, B] of the sensor is evenly divided into N temperature sub-intervals, where N is a preset positive integer value. This division method divides the operating temperature range into multiple small temperature ranges, and each temperature sub-interval represents a specific change stage of the internal temperature of the sensor. For example, if the operating temperature range is [20°C, 80°C] and N = 5 is preset, the width of each temperature sub-interval is (80 - 20) / 5 = 12°C, and the temperature sub-intervals are [20°C, 32°C), [32°C, 44°C), [44°C, 56°C), [56°C, 68°C), [68°C, 80°C]. This detailed division helps to more accurately monitor and control the change of the internal temperature of the sensor.

[0051] 2. Division of voltage sub-intervals: At the same time, the operating voltage range of the corresponding adjustable voltage output circuit is also evenly divided into N voltage sub-intervals. Similar to the temperature sub-intervals, the division of the voltage sub-intervals is also to divide the operating voltage range into multiple small voltage ranges, and each voltage sub-interval corresponds to a specific temperature sub-interval. For example, if the operating voltage range of the adjustable voltage output circuit is [5V, 15V] and N = 5 is also preset, the width of each voltage sub-interval is (15 - 5) / 5 = 2V, and the voltage sub-intervals are [5V, 7V), [7V, 9V), [9V, 11V), [11V, 13V), [13V, 15V].

[0052] II. One-to-one correspondence relationship and application of temperature sub-intervals and voltage sub-intervals:

[0053] 1. Establishment of the correspondence relationship: The temperature sub-intervals and the voltage sub-intervals correspond to each other in sequence. This means that each temperature sub-interval has a unique corresponding voltage sub-interval, and this correspondence relationship is preset and determined based on the characteristics of the sensor and experimental data. For example, the temperature sub-interval [20°C, 32°C) corresponds to the voltage sub-interval [5V, 7V), the temperature sub-interval [32°C, 44°C) corresponds to the voltage sub-interval [7V, 9V), and so on. This one-to-one correspondence relationship provides a clear basis for voltage adjustment to accurately control the internal temperature of the sensor.

[0054] 2. Basis for setting the working voltage: When the internal temperature of the semiconductor is within any temperature sub-interval, according to the above corresponding relationship, the working voltage of the adjustable voltage output circuit is set to the corresponding voltage sub-interval. The specific operation is as follows: Continuously monitor the internal temperature of the sensor. Once it is detected that the internal temperature enters a certain temperature sub-interval, immediately adjust the output voltage of the adjustable voltage output circuit so that it operates within the voltage sub-interval corresponding to this temperature sub-interval. For example, when the internal temperature of the sensor rises from 30°C to 35°C, that is, from the temperature sub-interval [20°C, 32°C) to [32°C, 44°C), the output voltage of the adjustable voltage output circuit will be adjusted from [5V, 7V) to [7V, 9V). In this way, it can be ensured that the sensor can obtain the most suitable working voltage at different internal temperature stages, thereby optimizing its linearity and improving the measurement accuracy and stability.

[0055] III. Verification and retesting of linearity:

[0056] The present invention sets N second test temperatures, and these second test temperatures form a one-to-one corresponding relationship with the pre-divided temperature sub-intervals. During the test process, whenever the second test temperature changes, the working voltage of the adjustable voltage output circuit matched with it will be automatically adjusted to the corresponding voltage sub-interval. At the same time, the indicators of the test gas sample will also be adjusted accordingly to ensure the accuracy and consistency of the test conditions.

[0057] At each second test temperature, the sensor will collect real-time gas indicator data. These data are recorded in detail for subsequent analysis. Based on these actually collected gas indicators, this method uses a specific calculation formula to evaluate the linearity R of the semiconductor sensor 2 . The formula is

[0058] ;

[0059] where y i is the output gas indicator corresponding to any second test temperature, is the average value of the actual gas indicators, is the actual gas indicator corresponding to any second test temperature. When the calculated linearity of the sensor is lower than the set standard, the test temperature threshold is reduced and retested.

[0060] When the calculated linearity of the sensor is lower than the preset performance standard, this method will automatically trigger the adjustment mechanism of the temperature threshold. Specifically, the system will reduce the test temperature threshold, thereby improving the accuracy of the slope value and enhancing the linearity and measurement accuracy of the sensor within the full temperature range.

[0061] The semiconductor gas sensor linearity optimization test method of the present invention involves accurate acquisition of the internal temperature of the sensor and the design of an adjustable voltage output circuit:

[0062] 1. Internal temperature collection technology:

[0063] 1. Core components for acquisition: The internal temperature acquisition of the semiconductor is based on the internal temperature sensor of the STM32 chip. As a high-performance microcontroller, the STM32 chip integrates a variety of functional modules, including a high-precision temperature sensor. The temperature sensor can sense the temperature changes inside the chip and the sensor closely connected to it in real time, providing an accurate data basis for subsequent temperature control and linearity optimization.

[0064] 2. ADC integration and voltage reading: The sensor integrates ADC (analog-to-digital converter), which is a key component for digitalizing temperature acquisition. Through ADC, the analog voltage signal sensed by the internal temperature sensor can be accurately converted into a digital signal. During the acquisition process, the system will read the voltage value of the internal temperature sensor. This voltage value is a direct reflection of the temperature change, and its change pattern is closely related to the actual temperature inside the sensor.

[0065] 3. Temperature conversion formula: The voltage value read cannot directly represent the temperature. It needs to be converted through a pre-set formula to obtain an accurate temperature value. This formula is based on the characteristics of the temperature sensor and experimental calibration data, and can establish an accurate correspondence between the voltage value and the temperature value. For example, suppose the formula is T = aV + b, where T represents temperature, V represents voltage value, and a and b are coefficients determined according to the characteristics of the sensor. Through this formula, the system can quickly and accurately convert the collected voltage value into a temperature value, thereby grasping the temperature status inside the sensor in real time.

[0066] 2. Adjustable voltage output circuit design:

[0067] 1. Heating control: The adjustable voltage output circuit adjusts the power of the heater based on the microprocessor and the digital potentiometer to heat the sensor. The microprocessor, as the control core of the entire circuit, can accurately control the resistance of the digital potentiometer according to the real-time data of the internal temperature of the sensor and the preset temperature control strategy. The change in the resistance of the digital potentiometer will directly affect the operating current of the heater, thereby changing the power output of the heater. When the sensor needs to be heated, the microprocessor will adjust the resistance of the digital potentiometer to gradually increase the power of the heater to increase the temperature inside the sensor until the predetermined temperature target is reached.

[0068] 2. Cooling control: Corresponding to the heating control, in the adjustable voltage output circuit, the sensor is cooled by adjusting the reference voltage or the resistance value in the feedback loop. During the cooling process, the microprocessor will fine-tune the reference voltage or the resistance value in the feedback loop according to the temperature feedback signal. This adjustment can change the gain characteristics of the circuit, thereby reducing the power output of the heater and achieving a decrease in the internal temperature of the sensor. For example, by reducing the reference voltage, the power of the heater can be reduced, thereby reducing heat generation and achieving the purpose of cooling; or by changing the resistance value in the feedback loop and adjusting the feedback coefficient of the circuit, fine control of the heater power can also be achieved, thus realizing the cooling effect.

[0069] 3. Working voltage waveform: The waveform of the working voltage of the adjustable voltage output circuit is an FM amplitude modulation wave. The FM amplitude modulation wave is a special modulation waveform, which is characterized by the combination of frequency modulation and amplitude modulation. Under this waveform, the frequency of the working voltage will change with the change of the temperature control signal, and at the same time, the amplitude of the voltage will also be modulated accordingly. The design of this amplitude modulation waveform enables the adjustable voltage output circuit to control the power of the heater more flexibly and efficiently, quickly respond to the temperature change requirements, and achieve precise control of the internal temperature of the sensor. For example, when rapid heating is required, the frequency and amplitude of the FM amplitude modulation wave can increase simultaneously, causing the heater to quickly output a large amount of heat; while when slow cooling is required, the frequency and amplitude can gradually decrease, causing the power of the heater to decrease smoothly and avoiding drastic temperature fluctuations.

[0070] The above has described a detailed embodiment of the present invention, but the content described is only a preferred embodiment of the present invention and cannot be considered as limiting the scope of implementation of the present invention. All equivalent changes and improvements made in accordance with the scope of the application of the present invention shall still fall within the scope covered by the patent of the present invention.

Claims

1. A linearity optimization test method for a semiconductor gas sensor, characterized in that: The following steps are involved: Obtain the operating temperature interval [A, B] when the linearity of the sensor is greater than the set standard, set n test temperatures T, n is a preset value, the test temperature is not within the operating temperature interval, and at any test temperature, collect the internal temperature t of the sensor in real time; For the i-th test temperature T i , i∈[1,n], if the test temperature is less than the interval temperature A, the adjustable voltage output circuit is controlled to heat the sensor. When the internal temperature t reaches A, the heating is suspended, and the sensor is continued to be heated after waiting for the set time. When the internal temperature reaches B, the heating is stopped; If the test temperature is greater than B, the adjustable voltage output circuit is controlled to cool the sensor. When the internal temperature t reaches B, the cooling is suspended, and the sensor is cooled again after the set time. When the internal temperature reaches A, the cooling is stopped. Draw a curve of the internal temperature of the sensor changing with time, obtain the slopes k1 and k2 when the internal temperature t passes through the A coordinate point and the B coordinate point respectively, convert the slopes into the corresponding temperature change rates v1 and v2, and calculate the balanced working voltages U1 and U2 of the adjustable voltage output circuit according to the temperature change rates. The calculation formula is: ； ； The unit of temperature change rate is Kelvin per second, ω is the preset correction coefficient, c is the specific heat capacity of the semiconductor material, m is the mass of the semiconductor material, and R is the resistance value of the semiconductor material at the current temperature; then for the i-th test temperature T i , when the test temperature is lower than the interval temperature A, the working voltage interval of the adjustable voltage output circuit is [U1, U2]; when the test temperature is higher than the interval temperature B, the working voltage interval of the adjustable voltage output circuit is [U2, U1]; When the test temperature is within [A, B], the internal temperature of the semiconductor is not collected, and the adjustable voltage output circuit stops working; The process of obtaining the slope is: Mark the time coordinate when the internal temperature of the sensor is A or B. After the adjustable voltage output circuit stops heating or cooling, monitor the curve of the internal temperature t of the sensor changing with time. When the internal temperature of the sensor reaches Aa or Bb, a and b are the test temperature thresholds. Get the time coordinate at this time, mark the slope of the line between the A coordinate point and the Aa coordinate point as k1, and mark the slope of the line between the B coordinate point and the Bb coordinate point as k2.

2. A linearity optimization test method for a semiconductor gas sensor according to claim 1, characterized in that: At any test temperature, the operating temperature interval [A, B] is evenly divided into N temperature sub-intervals, N is a preset value, and the corresponding operating voltage interval of the adjustable voltage output circuit is also evenly divided into N voltage sub-intervals. The temperature sub-intervals correspond to the voltage sub-intervals in sequence. When the internal temperature of the semiconductor is in any temperature sub-interval, the operating voltage of the adjustable voltage output circuit is set to the corresponding voltage sub-interval.

3. A linearity optimization test method for a semiconductor gas sensor according to claim 2, characterized in that: N second test temperatures are set, and the second test temperatures correspond to the temperature sub-intervals one by one. Whenever the second test temperature changes, the working voltage of the corresponding adjustable voltage output circuit is also adjusted to the corresponding voltage sub-interval, and the index of the test gas sample is also adjusted; the real-time gas index collected by the sensor at different second test temperatures is recorded, and the linearity R of the semiconductor sensor is calculated based on the actual gas index. 2 , the formula is: ； Among them, y i is the output gas index corresponding to any second test temperature, is the average value of the actual gas index, For any actual gas index corresponding to the second test temperature, when the calculated sensor linearity is lower than the set standard, the test temperature threshold is reduced and the test is performed again.

4. A linearity optimization test method for a semiconductor gas sensor according to claim 1, characterized in that: The n test temperatures are selected as follows: On both sides of the operating temperature range [A, B], several test temperatures are selected at fixed intervals, and the number of test temperatures on both sides is equal.

5. A linearity optimization test method for semiconductor gas sensors according to claim 1, characterized in that: The internal temperature of the semiconductor is collected based on the internal temperature sensor of the STM32 chip. The sensor integrates an ADC, reads the voltage value of the internal temperature sensor through the ADC, and converts it into temperature through a formula.

6. A linearity optimization test method for semiconductor gas sensors according to claim 1, characterized in that: The adjustable voltage output circuit adjusts the power of the heater based on the microprocessor and the digital potentiometer to heat the sensor; the adjustable voltage output circuit cools the sensor by adjusting the reference voltage or the resistance value in the feedback loop.

7. A linearity optimization test method for a semiconductor gas sensor according to claim 6, characterized in that: The waveform of the working voltage of the adjustable voltage output circuit is an FM amplitude modulation wave.

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