Air intake monitoring sensor

Abstract

This invention provides an airflow monitoring sensor, comprising: a substrate, a temperature sensor, and a micro-pressure sensor. Both the temperature sensor and the micro-pressure sensor are located on the substrate. The temperature sensor includes a thermistor fabricated using carbon nanotubes and two voltage-dividing resistors connected and surrounding the thermistor. The micro-pressure sensor includes four force-sensitive resistors fabricated using carbon nanotubes. Each force-sensitive resistor includes a strip-shaped extension and a protrusion, with the protrusion located on the side of the strip-shaped extension along its extension direction. The four force-sensitive resistors are connected sequentially to form a rectangle surrounding the temperature sensor. The linewidth of the force-sensitive resistors is greater than that of the thermistors. The temperature sensor and the micro-pressure sensor are integrated onto the substrate using 3D printing or nanoimprinting technology. This invention can improve the monitoring sensitivity and accuracy of the airflow monitoring sensor and reduce production costs.

Description

Technical Field

[0001] The present invention relates to the technical field of sensors, and in particular to an air intake volume monitoring sensor. Background Art

[0002] In the fields of precision instruments, air conditioners, server-type computer systems, etc., in order to ensure the safe operation of the system, it is necessary to monitor in real time whether the heat dissipation subsystem of the system in a relatively sealed and small space (such as a chassis) (such as whether the fan is working properly, whether the air intake flow is normal, etc.) is working properly. If the heat dissipation subsystem fails or the performance is degraded, it may cause the host system to shut down or even be seriously damaged. In addition, in air quality monitoring applications working in closed spaces, it is also necessary to ensure that air with a certain flow rate and velocity can flow through the sensor module (with a small chassis) to achieve effective monitoring and measurement. Since environmental factors such as dust and humidity can cause the air inlet filter to be blocked or degraded, the air intake may be reduced or even completely unable to enter, resulting in the heat of the equipment not being able to be dissipated in time and causing failure or damage, so it is necessary to pay attention to and monitor whether the air flow entering the chassis is normal.

[0003] Figure 1 This is a schematic diagram of the installation of a monitoring component in the prior art. Please refer to Figure 1 At present, the most common and low-cost solution in the industry is to install a filter on the rear of the air inlet filter 10 (in the windward direction ( Figure 1 The horizontal arrow in the middle indicates the windward direction)) installs a temperature monitoring component 20, which is a thermistor monitoring component, and uses the temperature monitoring component 20 to monitor whether the air inlet filter 10 is normal or whether the air inlet volume meets the requirements under different air inlet volumes. However, this method will produce false alarms (such as when the ambient temperature rises) when the ambient temperature changes as a whole, thereby causing system disorder.

[0004] Another method is to use a differential pressure sensor to measure the pressure difference between the inside and outside of the chassis to sense whether the air intake volume or the air inlet filter is normal, but this only applies to cases where the chassis space is relatively well sealed. For cases with open air outlets or air outlet channels, this method will also fail or produce false alarms. Of course, you can also manually check the filter regularly and clean it, but this method is cumbersome and not real-time. Summary of the invention

[0005] The object of the present invention is to provide an air intake volume monitoring sensor, which can improve the monitoring sensitivity and accuracy of the air intake volume monitoring sensor and reduce the production cost.

[0006] In order to achieve the above object, the present invention provides an air intake volume monitoring sensor, comprising:

[0007] substrate;

[0008] A temperature sensor is located on the substrate, and includes a thermistor made of carbon nanotubes and two voltage-dividing resistors, wherein the two voltage-dividing resistors are connected to and surround the thermistor;

[0009] A micro pressure sensor is located on the substrate, the micro pressure sensor includes four force sensitive resistors made of carbon nanotubes, each of the force sensitive resistors includes a strip-shaped extension portion and a protrusion, the protrusion is located on the side of the extension direction of the strip-shaped extension portion, and the four force sensitive resistors are connected in sequence to form a rectangle to surround the temperature sensor;

[0010] The line width of the force-sensitive resistor is greater than the line width of the thermistor, and the temperature sensor and the micro-pressure sensor are integrated on the substrate by using 3D printing technology or nano-imprinting technology.

[0011] Optionally, the protrusion is located at a center position of a side surface in an extending direction of the strip-shaped extending portion.

[0012] Optionally, the protrusion of each force-sensitive resistor is directed toward the temperature sensor.

[0013] Optionally, the shape of the protrusion includes rectangle, semicircle and triangle.

[0014] Optionally, along the extension direction of the strip-shaped extension portion, the equivalent length of the protrusion is smaller than the length of the strip-shaped extension portion; along the width direction of the strip-shaped extension portion, the equivalent width of the protrusion is smaller than the width of the strip-shaped extension portion.

[0015] Optionally, the size of the force-sensitive resistor is determined by a design model, and the design model is:

[0016] ;

[0017] ;

[0018] ;

[0019] ;

[0020] ;

[0021] Wherein, Max RT is the maximum response rate of the micro pressure sensor, W is the equivalent length of the force sensitive resistor, L is the equivalent width of the force sensitive resistor, ρ is the resistivity of the force sensitive resistor, T is the ambient temperature, and RT is max is the maximum response rate of the micro pressure sensor, W min and W maxare the minimum width and maximum width of the force sensitive resistor after equivalent design, L min and L max are the minimum length and maximum length of the force sensitive resistor after equivalent design, T low and T high are the lowest and highest temperatures given by the environment, S N is the power spectral density, S Nmax is the maximum thermal noise power spectral density given by the design.

[0022] Optionally, the thermistor is in a Japanese character shape.

[0023] Optionally, the minimum temperature change detected by the temperature sensor is 0.4°C, and the minimum pressure detected by the micro pressure sensor is 0.1g / m 2 .

[0024] Optionally, the substrate includes a rigid substrate or a flexible substrate.

[0025] In the air intake monitoring sensor provided by the present invention, carbon nanotubes are used to prepare thermistors of temperature sensors and force-sensitive resistors of micro-pressure sensors. Carbon nanotubes have excellent thermal, mechanical and electrical properties. Under different temperatures and pressures, the resistance will change accordingly and present different resistance characteristics to monitor temperature and pressure. In combination with the temperature sensor to measure temperature, temperature compensation of the micro-pressure sensor is achieved to avoid the influence of temperature on pressure, so that the measurement of the micro-pressure sensor is more accurate. Each force-sensitive resistor includes a strip-shaped extension and a protrusion. The protrusion is located on the side of the extension direction of the strip-shaped extension. Four force-sensitive resistors are connected in sequence to form a rectangle to surround the temperature sensor. The protrusion can adjust the response rate of the sensor and improve the sensitivity of the sensor to external pressure, thereby improving the monitoring sensitivity and accuracy of the air intake monitoring sensor. The temperature sensor and the micro-pressure sensor are integrated on the substrate by combining 3D printing technology or nanoimprinting technology, which is easy to integrate and produce, has high preparation accuracy, and can reduce production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The present invention is a schematic diagram of the installation of a monitoring component in the prior art.

[0027] Figure 2 A top view of an air intake volume monitoring sensor provided in accordance with an embodiment of the present invention.

[0028] Figure 3 A circuit diagram of a temperature sensor in an air intake volume monitoring sensor provided in an embodiment of the present invention.

[0029] Figure 4A circuit diagram of a micro pressure sensor in an air intake volume monitoring sensor provided in an embodiment of the present invention.

[0030] Figure 5 A schematic diagram of the working principle of the air intake volume monitoring sensor provided in Embodiment 1 of the present invention.

[0031] Wherein, the accompanying drawings are marked as follows:

[0032] 10-air inlet filter; 20-temperature monitoring component; 100-substrate; 200-temperature sensor; 210-thermistor; 220-voltage-dividing resistor; 300-micro pressure sensor; 310-force-sensitive resistor; 311-strip extension; 312-protrusion; 410-first pad; 420-second pad; 430-third pad. DETAILED DESCRIPTION

[0033] The specific implementation of the present invention will be described in more detail below in conjunction with the schematic diagram. The advantages and features of the present invention will become clearer based on the following description. It should be noted that the drawings are all in a very simplified form and are not in exact proportions, and are only used to facilitate and clearly assist in explaining the purpose of the embodiments of the present invention.

[0034] Figure 2 This is a top view of the air intake monitoring sensor provided in this embodiment. Please refer to Figure 2 In this embodiment, a sensor for monitoring air intake volume is provided, including: a substrate 100, a temperature sensor 200 and a micro pressure sensor 300, wherein the temperature sensor 200 and the micro pressure sensor 300 are both located on the substrate 100. In this embodiment, the temperature sensor 200 includes a thermistor 210 made of carbon nanotubes (CNT) and two voltage divider resistors 220, and the two voltage divider resistors 220 are connected and surround the thermistor 210. In this embodiment, the thermistor 210 is in the shape of a Japanese character (from Figure 2 (viewed horizontally), the shape of the thermistor 210 can better sense the ambient temperature, and the two voltage-dividing resistors 220 are both L-shaped, and the two voltage-dividing resistors 220 are connected to form a rectangle to surround the thermistor 210.

[0035] The micro pressure sensor 300 includes four force sensitive resistors 310 made of carbon nanotubes. Each force sensitive resistor 310 includes a strip-shaped extension portion 311 and a protrusion 312. The protrusion 312 is located on the side of the extension direction of the strip-shaped extension portion 311 ( Figure 2 As shown in the elliptical dotted box in the figure, the four force-sensitive resistors 310 are connected in sequence to form a rectangle to surround the temperature sensor 200. In this embodiment, the shape of the protrusion 312 includes a rectangle, a semicircle or a triangle. Figure 2The shape of the middle protrusion 312 is preferably rectangular. By providing the protrusion 312, the response rate of the sensor can be adjusted and the sensitivity of the sensor to external pressure can be improved.

[0036] Specifically, according to the resistance calculation formula, Figure 2 The resistance value of the force-sensitive resistor 310 is determined by its geometric parameters, length L, width W, height H and resistivity ρ, and the calculation formula is as follows:

[0037] ;

[0038] Taking the total differential of both ends of the above formula can be obtained:

[0039] ;

[0040] Arranging the above formula can get:

[0041] ;

[0042] ;

[0043] Dividing both sides of the above formula by R yields:

[0044] ;

[0045] That is, we can get:

[0046] ;

[0047] The left side of the above formula represents the sensitivity of the sensor to the change of the measured physical quantity and its ability to convert such change into a measurable signal. The response rate of the force sensitive resistor 310 is defined as RT:

[0048] ;

[0049] Under the same manufacturing process conditions, the height H and resistivity ρ of the force-sensitive resistor 310 are the same, that is, and are the same.

[0050] Assume that the length and width (measured length and measured width) of the strip-shaped extension 311 are L R and W R , the length and width (measured length and measured width) of the protrusion 312 are L r and W r , then the total resistance of the force sensitive resistor 310 is:

[0051] ;

[0052] Assuming that the equivalent length and equivalent width of the protrusion 312 acting on the strip extension 311 (i.e., the equivalent length and equivalent width of the protrusion 312) are l and w respectively, the equivalent length / width refers to the effective length / width of the current-carrying conductor under the action of the Ampere force in the magnetic field, then:

[0053] ;

[0054] The length and width of the equivalent force-sensitive resistor 310 are L and W respectively, L is L R +l,W is W R +w, then:

[0055] ;

[0056] It can be seen from the above formula that changing the equivalent length and equivalent width of the protrusion 312 can achieve the response rate of the sensor to improve the sensitivity of the sensor to external pressure. In this embodiment, the equivalent length of the force-sensitive resistor, the length of the strip-shaped extension, the length of the protrusion and the equivalent length of the protrusion all refer to its dimensions along the extension direction of the strip-shaped extension, and the equivalent width of the force-sensitive resistor, the width of the strip-shaped extension, the width of the protrusion and the equivalent width of the protrusion all refer to its dimensions along the width direction of the strip-shaped extension; along the extension direction of the strip-shaped extension, the equivalent length of the protrusion is less than the length of the strip-shaped extension (measured length); along the width direction of the strip-shaped extension, the equivalent width of the protrusion is less than the width of the strip-shaped extension (measured width).

[0057] Since the output signal of the micro pressure sensor is weak when it is stimulated by a small external pressure, the interference of the thermal noise of the device resistance on the output signal when the temperature changes needs to be considered in the device design. For thermal noise, its power spectrum density S N The calculation formula is:

[0058] ;

[0059] Where k is the Boltzmann constant, T is the absolute temperature, R is the resistance value, and Δf is the bandwidth.

[0060] In sensors, the power spectral density of thermal noise should be as small as possible to improve the signal-to-noise ratio (SNR) and the reliability of data transmission, thereby improving monitoring accuracy.

[0061] In order to obtain the optimal design structure, the key geometric dimensions of the device structure (force sensitive resistor 310) of the micro pressure sensor are determined by the following design model:

[0062] ;

[0063]

[0064] ;

[0065] ;

[0066] ;

[0067] ;

[0068] Wherein, Max RT is the maximum response rate of the micro pressure sensor, W is the equivalent length of the force sensitive resistor, L is the equivalent width of the force sensitive resistor, ρ is the resistivity of the force sensitive resistor, T is the ambient temperature, W min and W max are the minimum width and maximum width of the force sensitive resistor after equivalent design, L min and L max are the minimum length and maximum length of the force-sensitive resistor after equivalent design, T low and T high are the lowest and highest temperatures given by the environment, S N is the power spectral density, S Nmax The maximum thermal noise power spectrum density is designed, and st (subject to) is the constraint condition, which means that the design model is subject to the following four conditions. Through this design model, the optimal key design dimensions of the force-sensitive resistor under given conditions can be obtained.

[0069] In this embodiment, the protrusion 312 of each force-sensitive resistor 310 faces the temperature sensor 200, and the protrusion 312 is preferably located at the center position of the side surface in the extension direction of the strip-shaped extension portion 311. Providing the protrusion 312 at the center position of the side surface in the extension direction of the strip-shaped extension portion 311 can improve the sensitivity of pressure detection. When subjected to external pressure, the protrusion 312 is subjected to greater stress concentration, and this stress concentration will cause a significant change in resistivity, thereby improving the sensitivity of pressure detection. In addition, providing the protrusion 312 is conducive to stress distribution, thereby improving the measurement accuracy and stability of the sensor.

[0070] In this embodiment, carbon nanotubes are used as core sensitive materials to prepare thermistors 210 and force-sensitive resistors 310, and are combined with specific auxiliary materials to realize the perception of temperature and micro-pressure. The auxiliary materials may include one or more of high-density polyethylene (HDPE), antioxidants, conductive particles, non-conductive fillers, zinc oxide and calcium stearate, but are not limited to the above-mentioned auxiliary materials; wherein high-density polyethylene and carbon nanotubes are compounded to form a thermistor material with a PTC (positive temperature coefficient) effect; antioxidants are used to improve the antioxidant properties of the material to prevent the material from degrading due to oxidation during use; conductive particles are used to optimize the conductive network or improve the conductive properties of the material, and generally a small amount of conductive particles are added; non-conductive fillers are used to adjust the overall properties of the material, such as hardness, strength, etc.; zinc oxide and calcium stearate are used to improve the processing properties, stability or compatibility of the material with other components. Carbon nanotubes have excellent thermal, mechanical and electrical properties. Their thermal properties show good thermal conductivity, and their mechanical properties show good flexibility. The thermistor 210 with thermal properties prepared using carbon nanotubes can realize a high-sensitivity and high-precision temperature sensor 200. At different temperatures, the thermistor 210 with thermal properties has different resistivities. By measuring the resistance characteristics of the temperature sensor 200, the temperature can be sensed. And the force-sensitive resistor 310 with mechanical properties prepared using carbon nanotubes can realize a high-sensitivity and high-precision micro-pressure sensor 300. Under different pressures, the force-sensitive resistor 310 with mechanical properties will produce different degrees of deformation, and then present different resistance characteristics. By measuring the resistance characteristics of the micro-pressure sensor 300, the pressure can be sensed.

[0071] Of course, other semiconductor materials can also be used. Other semiconductor materials should also have effect characteristics that are sensitive to specific physical quantities. The effect characteristics can be used to convert various non-electrical physical quantities such as mechanical quantities, optical quantities, thermal quantities, magnetic quantities, and biological quantities into electrical signals. For example, thermosensitive semiconductor materials have a strong thermoelectric effect and can convert thermal quantities (temperature) into electrical signals. They are divided into positive temperature coefficients (when the temperature rises, the resistivity decreases) and negative temperature coefficients (when the temperature rises, the resistivity decreases), that is, the resistance value changes with the temperature. Therefore, using thermosensitive semiconductor materials to prepare a resistor structure with thermal characteristics can realize a high-sensitivity and high-precision temperature sensor. Force-sensitive semiconductor materials have a strong piezoresistive effect and can convert various mechanical quantities such as force, acceleration, flow, etc. into electrical signals. The piezoresistive effect refers to the physical phenomenon that when a semiconductor crystal is subjected to pressure, the symmetry of the crystal changes, and the conductive mechanism also changes accordingly, thereby changing the resistance value, that is, the resistance value changes with the pressure. Therefore, using force-sensitive semiconductor materials to prepare a resistor structure with mechanical characteristics can realize a high-sensitivity and high-precision micro-pressure sensor.

[0072] In this embodiment, the temperature sensor in the air intake sensor is mainly used to make the measurement result of the micro pressure sensor more accurate, which can be understood as the temperature compensation of the micro pressure sensor to avoid the influence of temperature on pressure, so that the measurement of the micro pressure sensor is more accurate. Therefore, when carbon nanotubes are used to prepare thermistors and force sensitive resistors, in order to ensure the sensitivity of the force sensitive resistors, the area of ​​the force sensitive resistors is required to be larger than the area of ​​the thermistors, and the line width of the force sensitive resistors is required to be larger than the line width of the thermistors (the equivalent width of the force sensitive resistors along the width direction of the strip extension is larger than the line width of the thermistors). In addition, the material concentrations (carbon nanotube material concentrations) used in preparing thermistors and force sensitive resistors are different.

[0073] In this embodiment, the temperature sensor 200 and the micro pressure sensor 300 are integrated on the substrate 100 by using 3D printing technology or nanoimprinting technology. In addition, precision printing technology can also be used. Specifically, the steps of using 3D printing technology include: providing a carbon nanotube solution (the carbon nanotube solution is doped with the above-mentioned auxiliary materials) and a 3D printer, based on the sensor digital model file preset in the 3D printer, using the nozzle of the 3D printer to spray the carbon nanotube solution on the substrate 100, so as to print and construct the thermistor 210 of the temperature sensor 200 and the force sensitive resistor 310 of the micro pressure sensor 300 layer by layer, and then bake; or, the steps of using nanoimprinting technology include: providing a template, the template has a sensor micro-nano structure, forming a carbon nanotube layer (the carbon nanotube layer is doped with the above-mentioned auxiliary materials) on the substrate 100, and imprinting the template on the carbon nanotube layer of the substrate 100, so as to transfer the sensor micro-nano structure to the substrate 100 to form the thermistor 210 of the temperature sensor 200 and the force sensitive resistor 310 of the micro pressure sensor 300. Compared with the conventional MEMS process, which is complex and has low precision, the processing of 3D printing technology is convenient and fast, with simple steps, and is suitable for the production of small batches of products. The processing of nanoimprint technology does not use visible light or ultraviolet light to process patterns, but uses mechanical means to transfer patterns, which can achieve very high resolution. In addition, the template can be used repeatedly, which greatly reduces the processing cost and effectively shortens the processing time. That is, nanoimprint technology has the technical advantages of ultra-high resolution, easy mass production, low cost, and high consistency.

[0074] In this embodiment, the substrate 100 may be a rigid substrate or a flexible substrate. For example, the material of the flexible substrate may be polyimide. The flexible substrate is suitable for more scenarios, such as narrow spaces, special-shaped surface mounting, and the like.

[0075] In this embodiment, the thermistor 210 of the temperature sensor 200 and the force-sensitive resistor 310 of the micro-pressure sensor 300 both have a specific geometric topological structure, and utilize their sensitivity to micro-pressure and thermal fields to achieve the perception of micro-pressure generated by ambient temperature and air intake volume.

[0076] In this embodiment, the temperature sensor 200 further includes a first pad 410 and a second pad 420, which are respectively formed by opening holes in the thermistor 210 and the voltage-dividing resistor 220 and then filling them with metal. Specifically, first pads 410 are provided at both distal ends of the thermistor 210 (located at two diagonals of the "day"-shaped structure), and second pads 420 are provided at both distal ends of the two voltage-dividing resistors 220 (located at two diagonals of the rectangle).

[0077] In this embodiment, the micro pressure sensor 300 further includes a third pad 430, and a third pad 430 is provided between two adjacent force-sensitive resistors 310. Similarly, the third pad 430 is formed by opening a hole in the force-sensitive resistor 310 and then filling it with metal.

[0078] In this embodiment, the voltage-dividing resistor 220 should have high precision and stability, a small temperature coefficient, and an alloy material can be selected. To improve the measurement accuracy, the resistance values of the voltage-dividing resistor 220, the thermistor 210, and the force-sensitive resistor 310 are preferably the same, which is beneficial to improving the accuracy and stability of the measurement results. In this embodiment, the minimum change temperature monitored by the temperature sensor is 0.4 °C, and the minimum pressure monitored by the micro pressure sensor is 0.1 g / m 2 , and it can achieve high-sensitivity and high-precision monitoring of the air intake volume pressure and the ambient temperature.

[0079] When the sensor is applied, the first second pad 420 and the first third pad 430 are connected to the power supply through the binding lead method, the first first pad 410 and the second third pad 430 are connected to the ground wire, the second first pad 410 and the second second pad 420 are connected to each other, and the third third pad 430 and the fourth third pad 430 (the third third pad 430 and the fourth third pad 430 are located at the diagonals of the formed rectangle) are connected to each other; among them, after the first first pad 410 and the second first pad 410 are connected, they serve as the output voltage pins of the temperature sensor, and after the third third pad 430 and the fourth third pad 430 are connected, they serve as the output voltage pins of the micro pressure sensor.

[0080] Figure 3 is the circuit schematic diagram of the temperature sensor in the air intake volume monitoring sensor provided in this embodiment, Figure 4 is the circuit schematic diagram of the micro pressure sensor in the air intake volume monitoring sensor provided in this embodiment. Please refer to Figure 3 , the temperature sensor includes a thermistor and two voltage-dividing resistors, and the relationship between the resistance value of the thermistor and the temperature is as follows:

[0081] ;

[0082] Among them, R t is the resistance of the thermistor at temperature T, R0 is the resistance of the thermistor at temperature T0 (usually 25°C), and α is the linear temperature coefficient.

[0083] The output voltage of the temperature sensor is related as follows:

[0084] ;

[0085] Among them, Rs1 and Rs2 are the resistance values ​​of two voltage-dividing resistors, Rs1 / / Rs2 is the parallel resistance value of the two voltage-dividing resistors, Vs1 is the power supply voltage of the temperature sensor, and Vo1 is the output voltage of the temperature sensor.

[0086] Please refer to Figure 4 The micro pressure sensor includes four force-sensitive resistors to form a Wheatstone bridge. Theoretically, the resistance of the four force-sensitive resistors is the same at the beginning. At this time, the bridge is balanced under zero input and the output voltage is zero. When the micro pressure sensor is subjected to external pressure, the four force-sensitive resistors will deform and the resistance of the force-sensitive resistors will change. At this time, the bridge loses balance and the output voltage of the bridge is:

[0087] ;

[0088] Among them, Rs3, Rs4, Rs5, and Rs6 are the resistance values ​​of the four force-sensitive resistors in the zero input state, ΔRs3, ΔRs4, ΔRs5, and ΔRs6 are the resistance changes of the force-sensitive resistors caused by pressure (zero in the zero input state), Vs2 is the power supply voltage of the micro-pressure sensor, Vo2 is the output voltage of the micro-pressure sensor, and the resistance values ​​of the four force-sensitive resistors are the same.

[0089] In this embodiment, the temperature sensor and the micro-pressure sensor adopt a composite structure. The pressure and temperature collection area in this structure is increased, and the corresponding pressure and temperature detection accuracy is improved; and the four force-sensitive resistors 310 are connected in sequence to form a rectangle and surround the temperature sensor, which is more sensitive to pressure in all directions and improves the accuracy of pressure detection.

[0090] Figure 5 This is a schematic diagram of the working principle of the air intake volume monitoring sensor provided in this embodiment. Figure 5 The micro pressure sensor on the substrate collects the pressure value of the air intake at the air inlet, and the resistance change of the force sensitive resistor is obtained by obtaining the resistance change amount 1, and then the voltage data 1 is obtained by the output voltage change of the circuit; the temperature sensor collects the temperature value of the air inlet, and the resistance change of the thermistor is obtained by obtaining the resistance change amount 2, and then the voltage data 2 is obtained by the output voltage change of the circuit; the air intake volume monitoring sensor will store the voltage data 1 and the voltage data 2 through the data storage unit, and finally the data output unit will output the monitoring results.

[0091] In summary, in the air intake monitoring sensor provided by the present invention, carbon nanotubes are used to prepare thermistors of temperature sensors and force-sensitive resistors of micro-pressure sensors. Carbon nanotubes have excellent thermal, mechanical and electrical properties. Under different temperatures and pressures, the resistance will change accordingly and present different resistance characteristics to monitor temperature and pressure, and the temperature sensor is combined to measure the temperature to achieve temperature compensation of the micro-pressure sensor to avoid the influence of temperature on pressure, so that the measurement of the micro-pressure sensor is more accurate; each force-sensitive resistor includes a strip-shaped extension portion and a protrusion, and the protrusion is located on the side of the extension direction of the strip-shaped extension portion. Four force-sensitive resistors are connected in sequence to form a rectangle to surround the temperature sensor. The protrusion can adjust the response rate of the sensor and improve the sensitivity of the sensor to external pressure, thereby improving the monitoring sensitivity and accuracy of the air intake monitoring sensor; the temperature sensor and the micro-pressure sensor are integrated on the substrate by combining 3D printing technology or nanoimprinting technology, which is easy to integrate and produce, has high preparation accuracy, and can reduce production costs.

[0092] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any technician in the relevant technical field, without departing from the scope of the technical solution of the present invention, makes any form of equivalent replacement or modification to the technical solution and technical content disclosed in the present invention, which does not depart from the content of the technical solution of the present invention and still falls within the protection scope of the present invention.

Claims

1. An air intake volume monitoring sensor, characterized in that: include: substrate; A temperature sensor is located on the substrate, and includes a thermistor made of carbon nanotubes and two voltage-dividing resistors, wherein the two voltage-dividing resistors are connected to and surround the thermistor; A micro pressure sensor is located on the substrate, the micro pressure sensor includes four force sensitive resistors made of carbon nanotubes, each of the force sensitive resistors includes a strip-shaped extension portion and a protrusion, the protrusion is located on the side of the extension direction of the strip-shaped extension portion, and the four force sensitive resistors are connected in sequence to form a rectangle to surround the temperature sensor; The line width of the force-sensitive resistor is greater than the line width of the thermistor, and the temperature sensor and the micro-pressure sensor are integrated on the substrate by using 3D printing technology or nano-imprinting technology.

2. The air intake volume monitoring sensor according to claim 1, characterized in that: The protruding portion is located at a center position of a side surface of the strip-shaped extending portion in an extending direction.

3. The air intake volume monitoring sensor according to claim 1, characterized in that: The protrusion of each of the force-sensitive resistors faces the temperature sensor.

4. The air intake volume monitoring sensor according to claim 1, characterized in that: The shapes of the protrusions include rectangle, semicircle and triangle.

5. The air intake volume monitoring sensor according to claim 1, characterized in that: Along the extension direction of the strip-shaped extension portion, the equivalent length of the protrusion is smaller than the length of the strip-shaped extension portion; along the width direction of the strip-shaped extension portion, the equivalent width of the protrusion is smaller than the width of the strip-shaped extension portion.

6. The air intake volume monitoring sensor according to claim 1, characterized in that: The size of the force-sensitive resistor is determined by a design model, which is: ； ； ； ； ； Wherein, Max RT is the maximum response rate of the micro pressure sensor, W is the equivalent length of the force sensitive resistor, L is the equivalent width of the force sensitive resistor, ρ is the resistivity of the force sensitive resistor, T is the ambient temperature, W min and W max are the minimum width and maximum width of the force sensitive resistor after equivalent design, L min and L max are the minimum length and maximum length of the force sensitive resistor after equivalent design, T low and T high are the lowest and highest temperatures given by the environment, S N is the power spectral density, S Nmax is the maximum thermal noise power spectral density given by the design.

7. The air intake volume monitoring sensor according to claim 1, characterized in that: The thermistor is in a Japanese character shape.

8. The air intake volume monitoring sensor according to claim 1, characterized in that: The minimum temperature change detected by the temperature sensor is 0.4°C, and the minimum pressure detected by the micro pressure sensor is 0.1g / m 2 .

9. The air intake monitoring sensor according to claim 1, characterized in that: The substrate includes a rigid substrate or a flexible substrate.

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