Voltage transformation and humidity regulation device and method for testing and calibrating MEMS (Micro Electro Mechanical System) humidity-sensitive device

Abstract

The invention discloses a variable-pressure humidity regulating device and method for testing and calibrating an MEMS humidity-sensitive device. The device comprises a gas source, a first back pressure type pressure regulating valve, a saturator, a constant-temperature system, a water path, a second back pressure type pressure regulating valve and a mass flow controller. Gas from a gas source enters the saturator through the first back pressure type pressure regulating valve and then enters the MEMS humidity-sensitive device measuring cavity through the second back pressure type pressure regulating valve, a gas outlet of the MEMS humidity-sensitive device measuring cavity is connected with the mass flow controller, and the mass flow controller controls the gas flow in the MEMS humidity-sensitive device measuring cavity. The first back pressure type pressure regulating valve controls the pressure in the saturator, the second back pressure type pressure regulating valve controls the pressure in the measuring cavity of the MEMS humidity-sensitive device, the constant temperature system and the water path adjust the temperature of the saturator, and moisture generated by the saturator enters the measuring cavity of the MEMS humidity-sensitive device to be measured and calibrated. According to the invention, rapid response of specific humidity parameters with wide range, high accuracy and high stability can be realized, and effective measurement and calibration of the MEMS humidity-sensitive device can be realized.

Description

Technical Field

[0001] The invention belongs to the field of thermal metrology, and in particular relates to a variable voltage humidity control device and method for testing and calibrating a MEMS humidity sensitive device. Background Art

[0002] With the increasing application of MEMS humidity sensors in various fields and the continuous expansion of the domestic chip industry, the demand for large-scale calibration of MEMS humidity sensors is imminent. Among them, a humidity generator is needed to achieve rapid excitation of specific humidity parameters in order to correctly test the ability of MEMS humidity sensors to convert physical inputs into electrical outputs under current working conditions. At the same time, the calibration of MEMS humidity sensors also requires the humidity generator to cover a dew point temperature range of -35°C to 90°C, 7×24h long-term operation without stopping, the pressure in the measurement cavity of the MEMS humidity sensor can be adjusted arbitrarily, and the flow rate can be adjusted arbitrarily in the range of 0 to 30L / min, to meet the simultaneous online calibration of large quantities of MEMS humidity sensors.

[0003] At present, humidity generating devices are mostly used to generate humidity at normal pressure. Some humidity generating devices have a fast dew point temperature switching speed, but a narrow dew point temperature range, low accuracy, and poor stability; other humidity generating devices have good stability and high accuracy, but a slow dew point temperature switching speed. Therefore, existing humidity generating devices cannot meet the measurement and calibration requirements of MEMS humidity-sensitive devices. Summary of the invention

[0004] The purpose of the present invention is to provide a variable voltage humidity control device and method for testing and calibrating MEMS humidity sensitive devices, which can achieve rapid response of specific humidity parameters with wide range, high accuracy and high stability, and realize effective measurement and calibration of MEMS humidity sensitive devices.

[0005] In order to achieve the above-mentioned object, one aspect of the present invention provides a variable pressure humidity control device for testing and calibrating a MEMS humidity sensitive device, comprising an air source, a first back-pressure regulating valve, a saturator, a constant temperature system and a water circuit, a second back-pressure regulating valve, and a mass flow controller;

[0006] The gas from the gas source enters the saturator through the first back-pressure regulating valve, and then enters the MEMS humidity sensor measurement cavity through the second back-pressure regulating valve. The gas outlet of the MEMS humidity sensor measurement cavity is connected to the mass flow controller, and the mass flow controller is used to control the gas flow in the MEMS humidity sensor measurement cavity.

[0007] The first back-pressure regulating valve is used to control the pressure in the saturator, the second back-pressure regulating valve is used to control the pressure in the measurement cavity of the MEMS humidity sensor, the constant temperature system and the water circuit are connected to the saturator to adjust the temperature of the saturator, and the moisture generated by the saturator enters the measurement cavity of the MEMS humidity sensor for measurement and calibration;

[0008] The constant temperature system and water circuit include a constant temperature system, a liquid storage tank, an inlet water circuit and an outlet water circuit. The constant temperature system is used to control the temperature in the liquid storage tank to produce circulating water with constant temperature. The circulating water enters the saturator through the inlet water circuit and returns to the liquid storage tank from the saturator through the outlet water circuit.

[0009] Preferably, an adjustable flow pump and a one-way valve are provided on the water inlet waterway. The adjustable flow valve is used to control the flow of water in the saturator, and the one-way valve is used to avoid water backflow due to increased pressure in the saturator.

[0010] Another aspect of the present invention provides a variable voltage humidity control method for testing and calibrating a MEMS humidity sensor. The above device is used to test and calibrate the MEMS humidity sensor. The method includes:

[0011] After the saturator temperature is raised to the specified temperature and stabilized by the constant temperature system, the second back-pressure regulating valve is closed, the gas source is opened, the first back-pressure regulating valve is set to increase the pressure to the pressure corresponding to the dew point temperature and stabilize, the mass flow controller is set to a specified flow rate, the second back-pressure regulating valve is set to a specified pressure, the second back-pressure regulating valve is opened, and the dew point temperature of the outlet gas at the specified pressure is obtained, which is transported to the MEMS humidity sensor measurement chamber for testing and calibration.

[0012] Preferably, the constant temperature system is set to different temperature points respectively, and by adjusting the first back-pressure regulating valve and the second back-pressure regulating valve, the pressure in the saturator covers the ranges of 0.1013-1.6743MPa, 0.1013-1.5019MPa, and 0.3085-2.8022MPa respectively, achieving dew point temperatures in the ranges of 90-30°C, 30--10°C, and -10--35°C.

[0013] Preferably, the constant temperature system is set to 90°C, 30°C, and 5°C.

[0014] The voltage-variable humidity control device and method for testing and calibrating MEMS humidity-sensitive devices according to the above aspects of the present invention can achieve rapid response to specific humidity parameters with a wide range, high accuracy and high stability, and realize effective measurement and calibration of MEMS humidity-sensitive devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings used in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work:

[0016] Figure 1 It is a structural schematic diagram of a voltage-variable humidity control device for testing and calibrating a MEMS humidity-sensitive device according to an embodiment of the present invention;

[0017] Figure 2 It is a structural schematic diagram of a constant temperature system and a water circuit according to an embodiment of the present invention. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments 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.

[0019] One embodiment of the present invention provides a variable voltage humidity control device for testing and calibrating a MEMS humidity sensitive device, such as Figure 1 As shown, the variable pressure humidity regulating device of the embodiment of the present invention includes an air source, a first back pressure regulating valve (back pressure regulating valve 1), a saturator, a constant temperature system and water circuit, a second back pressure regulating valve (back pressure regulating valve 2), and a mass flow controller.

[0020] The gas from the gas source enters the saturator through the first back-pressure regulating valve and then enters the MEMS humidity sensor measurement chamber through the second back-pressure regulating valve. The gas outlet of the MEMS humidity sensor measurement chamber is connected to a mass flow controller to control the flow of the entire gas path. The first back-pressure regulating valve controls the pressure in the saturator, and the second back-pressure regulating valve controls the pressure in the MEMS humidity sensor measurement chamber.

[0021] The first back pressure regulating valve is used to control the pressure in the saturator, and the constant temperature system and water circuit are used to adjust the temperature of the saturator. Figure 2 As shown, the thermostatic system and water circuit include a thermostatic system, a liquid storage tank, an inlet water circuit and an outlet water circuit. The thermostatic system is used to control the temperature in the liquid storage tank to produce circulating water with a constant and adjustable temperature. The circulating water enters the saturator through the inlet water circuit and returns from the saturator to the liquid storage tank through the outlet water circuit. An adjustable flow pump and a one-way valve are provided on the inlet water circuit. The adjustable flow valve is used to control the flow of water in the saturator, and the one-way valve is used to avoid water reflux due to the increase of pressure in the saturator.

[0022] The circulating water flows through the saturator, which can achieve the rapid balance of the internal temperature of the saturator and the real-time water replenishment function, produce saturated moisture at a certain temperature and pressure, and effectively improve the saturation efficiency of the saturator.

[0023] The second back pressure regulating valve is used to control the pressure in the measurement cavity of the MEMS humidity sensor and deliver standard wet gas into the measurement cavity of the MEMS humidity sensor for calibration. The mass flow controller is used to control the outlet flow of the overall gas path, that is, the gas flow in the measurement cavity of the MEMS humidity sensor.

[0024] The embodiment of the present invention also provides a variable pressure humidity control method for testing and calibrating MEMS humidity sensors. The above-mentioned variable pressure humidity control device is used to test and calibrate MEMS humidity sensors. The working process is as follows: before starting the measurement and calibration, the constant temperature system is turned on, the saturator temperature is raised to the specified temperature and stabilized, the second back pressure regulating valve is closed, the gas source is turned on, the first back pressure regulating valve is set to increase the pressure to the specified pressure corresponding to the dew point temperature and stabilized, the mass flow controller is set to the specified flow, the second back pressure regulating valve is set to the specified pressure, and the second back pressure regulating valve is opened. At this time, the outlet gas of the device is the dew point temperature under the specified pressure, and is transported to the measurement chamber of the MEMS humidity sensor for measurement and calibration. When the dew point temperature needs to be adjusted, the set pressure of the first back pressure regulating valve can be directly adjusted to achieve this, and when the outlet pressure needs to be adjusted, the set pressure of the second back pressure regulating valve can be directly adjusted to achieve this.

[0025] Take the calibration initial dew point temperature of 90℃ as an example. Before starting the calibration, turn on the constant temperature system, raise the saturator temperature to 90℃ and stabilize it, close the second back pressure regulating valve, turn on the gas source, set the pressure of the first back pressure regulating valve to 0.1013MPa (i.e., the pressure in the saturator is 0.1013MPa) and stabilize it, set the flow rate of the mass flow controller to 5L / min, set the pressure of the second back pressure regulating valve to 0.1013MPa (i.e., the pressure in the MEMS sensor measurement cavity is 0.1013MPa), open the second back pressure regulating valve, and the outlet dew point temperature of the device is 90℃. At this time, when the dew point temperature of the next calibration point is 40℃, adjust the pressure of the first back pressure regulating valve to 0.9623MPa, and the pressure of the second back pressure regulating valve to 0.1013MPa. After the pressure stabilizes, the outlet dew point temperature of the device is 40℃. The pressure balance time is within 10min, which can achieve the purpose of rapid adjustment.

[0026] The variable pressure humidity regulating device of the embodiment of the present invention realizes the occurrence of the entire dew point temperature range by regulating the pressure in different temperature stages. It can be calculated by the following dew point temperature calculation formula. When the constant temperature system sets several different temperature points respectively, the embodiment of the present invention is set to 90°C, 30°C, and 5°C. By adjusting the first back-pressure regulating valve and the second back-pressure regulating valve, the pressure in the saturator covers the ranges of (0.1013~1.6743)MPa, (0.1013~1.5019)MPa, and (0.3085~2.8022)MPa respectively, and the dew point temperature ranges of (90~30)°C, (30~-10)°C, and (-10~-35)°C can be achieved.

[0027] The corresponding relationship between the dew point temperature and the set pressure of the first and second back pressure regulating valves can be expressed as:

[0028]

[0029] Where:

[0030] e w -Saturated water vapor pressure (Pa);

[0031] T s - is the temperature inside the saturator, °C;

[0032] e w (T s )-saturator temperature is T s Saturated water vapor pressure (Pa);

[0033] T d -dew point temperature, °C;

[0034] e w (T d )-dew point temperature is T d Saturated water vapor pressure (Pa);

[0035] P s - is the set pressure of the first back-pressure regulating valve (i.e., the pressure in the saturator), Pa;

[0036] P c - is the set pressure of the second back-pressure regulating valve (i.e., the pressure in the cavity measured by the MEMS sensor), Pa;

[0037] c i -coefficient;

[0038] d i -coefficient.

[0039] The variable voltage humidity control device and method of the embodiment of the present invention can achieve a fast response to a specific humidity parameter with a wide range, high accuracy and high stability, realize effective measurement and calibration of MEMS humidity-sensitive devices, and solve the problem that the dew point temperature switching speed of the humidity generating device is slow, resulting in the inability to test and calibrate the MEMS humidity-sensitive devices.

[0040] The above description is only by way of illustration of certain exemplary embodiments of the present invention. It is undoubted that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A variable voltage humidity control device for testing and calibrating MEMS humidity sensitive devices, characterized in that: It includes a gas source, a first back-pressure regulating valve, a saturator, a constant temperature system and a water circuit, a second back-pressure regulating valve, and a mass flow controller; The gas from the gas source enters the saturator through the first back-pressure regulating valve, and then enters the MEMS humidity sensor measurement cavity through the second back-pressure regulating valve. The gas outlet of the MEMS humidity sensor measurement cavity is connected to the mass flow controller, and the mass flow controller is used to control the gas flow in the MEMS humidity sensor measurement cavity. The first back-pressure regulating valve is used to control the pressure in the saturator, the second back-pressure regulating valve is used to control the pressure in the measurement cavity of the MEMS humidity sensor, the constant temperature system and the water circuit are connected to the saturator to adjust the temperature of the saturator, and the moisture generated by the saturator enters the measurement cavity of the MEMS humidity sensor for measurement and calibration; The constant temperature system and water circuit include a constant temperature system, a liquid storage tank, an inlet water circuit and an outlet water circuit. The constant temperature system is used to control the temperature in the liquid storage tank to produce circulating water with constant temperature. The circulating water enters the saturator through the inlet water circuit and returns to the liquid storage tank from the saturator through the outlet water circuit.

2. The device according to claim 1, characterized in that An adjustable flow pump and a one-way valve are provided on the water inlet waterway. The adjustable flow valve is used to control the flow of water in the saturator, and the one-way valve is used to avoid water backflow due to increased pressure in the saturator.

3. A variable voltage humidity control method for testing and calibrating a MEMS humidity sensitive device, characterized in that: The device according to claim 1 or 2 is used to test and calibrate a MEMS humidity-sensitive device, the method comprising: After the saturator temperature is raised to the specified temperature and stabilized by the constant temperature system, the second back-pressure regulating valve is closed, the gas source is opened, the first back-pressure regulating valve is set to increase the pressure to the pressure corresponding to the dew point temperature and stabilize, the mass flow controller is set to a specified flow rate, the second back-pressure regulating valve is set to a specified pressure, the second back-pressure regulating valve is opened, and the dew point temperature of the outlet gas at the specified pressure is obtained, which is transported to the MEMS humidity sensor measurement chamber for testing and calibration.

4. The method according to claim 3, characterized in that The constant temperature system is set to different temperature points. By adjusting the first back-pressure regulating valve and the second back-pressure regulating valve, the pressure in the saturator covers the ranges of 0.1013-1.6743MPa, 0.1013-1.5019MPa, and 0.3085-2.8022MPa, respectively, and the dew point temperature ranges of 90-30℃, 30--10℃, and -10--35℃ are achieved.

5. The method according to claim 4, characterized in that The constant temperature system was set to 90°C, 30°C, and 5°C.

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