CN215059956U - MEMS mass flow controller based on piezoelectric control valve - Google Patents
MEMS mass flow controller based on piezoelectric control valve Download PDFInfo
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- CN215059956U CN215059956U CN202120675603.7U CN202120675603U CN215059956U CN 215059956 U CN215059956 U CN 215059956U CN 202120675603 U CN202120675603 U CN 202120675603U CN 215059956 U CN215059956 U CN 215059956U
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Abstract
The utility model discloses a MEMS mass flow controller based on a piezoelectric control valve, which comprises a shell, a mass flow sensor and a piezoelectric diaphragm, wherein the mass flow sensor and the piezoelectric diaphragm are positioned in the shell; the mass flow sensor is arranged on one side, close to the inlet of the airflow channel, of the lower substrate; the piezoelectric diaphragm is arranged on one side, close to the outlet of the airflow channel, of the lower substrate; the piezoelectric diaphragm is arranged on the lower substrate at two ends, and a vibration gap is arranged between the middle part of the piezoelectric diaphragm and the lower substrate. The utility model utilizes the mass flow sensor to accurately measure and feed back the gas flow in real time, and the mass flow sensor is used as the adjusting basis of the driving voltage of the piezoelectric diaphragm, thereby utilizing the deformation of the piezoelectric diaphragm to realize the high-precision control of the micro flow; furthermore, the utility model has the advantages of simple structure, small, with low costs, preparation controllability are strong.
Description
Technical Field
The utility model relates to a flow observes and controls technical field, in particular to MEMS mass flow controller based on piezoelectric control valve.
Background
Flow measurement and control are essential requirements for industrial production and scientific research. The mass flow controller is a device capable of directly measuring and controlling the mass flow of gas, and plays an important role in various fields of semiconductors, integrated circuits, petrochemical industry, vacuum coating, medicines, environmental protection and the like. The core components of a mass flow controller include a mass flow sensor and an electromagnetic regulating valve. The sensor can realize accurate measurement of gas mass flow, and the electromagnetic regulating valve can regulate and control the flow according to the measurement result.
At present, in a domestic mass flow controller, a sensor generally utilizes the principle of a capillary heat transfer temperature difference calorimetry, a group of thermistor wires are respectively manufactured at the upstream and the downstream of a capillary, and two precision resistors are externally connected to form an electric bridge structure. When the gas flow sensor works, the electric bridge is heated, if airflow passes through the electric bridge, the temperature of the thermistor wires at the upstream and downstream is different, and the electric bridge outputs a voltage signal which is proportional to the mass flow of the gas. Solenoid valves are typically assembled from a number of precision machined components. The controller has complex manufacturing process, high price and poor precision when controlling the micro flow; in addition, the problems of zero drift and particulate pollution exist after long-term use, and the maintenance cost is high.
With the rapid development of the MEMS technology, the sensor and the actuator manufactured by the technology are concerned with due to the advantages of simple structure, small volume, low cost, high precision, etc. Therefore, it is of great interest to develop a MEMS mass flow controller.
SUMMERY OF THE UTILITY MODEL
In order to solve the technical problem, the utility model provides a MEMS mass flow controller based on piezoelectric control valve has simple structure, small, with low costs, the strong characteristics of preparation controllability, is fit for the high accuracy control of small flow.
In order to achieve the above purpose, the technical scheme of the utility model is as follows:
an MEMS mass flow controller based on a piezoelectric control valve comprises a shell, a mass flow sensor and a piezoelectric diaphragm, wherein the mass flow sensor and the piezoelectric diaphragm are positioned in the shell; the mass flow sensor is arranged on one side, close to the inlet of the airflow channel, of the lower substrate; the piezoelectric diaphragm is arranged on one side, close to the outlet of the airflow channel, of the lower substrate; the piezoelectric diaphragm is arranged on the lower substrate at two ends, and a vibration gap is arranged between the middle part of the piezoelectric diaphragm and the lower substrate.
In the above scheme, the position of the piezoelectric diaphragm is lower than the position of the mass flow sensor, a downward protrusion is arranged at the position, corresponding to the piezoelectric diaphragm, of the inner side of the upper cover plate, and the protrusion is used for limiting the trend of the airflow channel.
In the above aspect, the mass flow sensor includes:
the substrate is provided with a heat insulation cavity which is communicated along the vertical direction;
the supporting layer is formed on the substrate and the heat insulation cavity;
the heating element is formed on the upper surface of the supporting layer and is locally positioned above the heat insulation cavity;
the temperature sensing elements are formed on the upper surface of the supporting layer, are symmetrically distributed on two sides of the heating element and are locally positioned above the heat insulation cavity;
the metal layer is formed on the upper surface of the supporting layer;
the insulating layer covers the heating element, the temperature sensing element and the metal layer, and a contact hole exposing part of the metal layer is formed on the insulating layer through local etching.
Through the technical scheme, the utility model provides a pair of MEMS mass flow controller based on piezoelectric control valve has following beneficial effect:
the MEMS mass flow controller based on the piezoelectric control valve provided by the utility model is manufactured by adopting the MEMS process, has the characteristics of simple structure, small volume and low cost, avoids the complex preparation process and has strong controllability; the utility model discloses the utilization carries out the precision measurement to gas flow based on the MEMS mass flow sensor of piezoelectric control valve to regard measuring voltage as the feedback quantity, be used for guiding the driving voltage who adjusts the piezoelectric diaphragm, and then utilize the deformation realization of piezoelectric diaphragm to the accurate control of flow, consequently, the utility model provides a MEMS mass flow controller based on piezoelectric control valve is stable high, can realize the high accuracy measurement and the control of small flow. In addition, the control range of the flow can be adjusted by adjusting the thickness of the piezoelectric diaphragm.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below.
Fig. 1 is a schematic structural diagram (initial state) of a MEMS mass flow controller based on a piezoelectric control valve according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram (working state) of a MEMS mass flow controller based on a piezoelectric control valve according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram (initial state) of a MEMS mass flow controller based on a piezoelectric control valve according to a second embodiment of the present invention;
fig. 4 is a schematic structural diagram (working state) of a MEMS mass flow controller based on a piezoelectric control valve according to a second embodiment of the present invention;
fig. 5 is a schematic cross-sectional view of a mass flow sensor employed in an embodiment of the present invention;
in the figure, 1, a housing; 101. a lower substrate; 102. an upper cover plate; 103. an air flow channel; 104. an inlet; 105. an outlet; 106. a protrusion; 107. a vibration gap; 2. a mass flow sensor; 201. a substrate; 202. a support layer; 203. a heating element; 204. a temperature sensing element; 205. a metal layer; 206. an insulating layer; 207. a contact hole; 208. a heat insulating cavity; 3. a piezoelectric diaphragm.
Detailed Description
The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.
The utility model provides a MEMS mass flow controller based on piezoelectric control valve, specific embodiment is as follows:
example one
Referring to fig. 1 and 2, an MEMS mass flow controller based on a piezoelectric control valve includes a housing 1, a mass flow sensor 2, and a piezoelectric diaphragm 3; the housing 1 comprises a lower substrate 101, an upper cover plate 102 and an airflow channel 103 enclosed by the two; the mass flow rate sensor 2 is disposed on the opposite left side of the lower substrate 101, i.e., on the side close to the inlet 104 of the gas flow channel 103; the piezoelectric membrane 3 is arranged on the opposite right side of the lower substrate 101, namely, the side close to the outlet 105 of the air flow channel 103, the position of the piezoelectric membrane 3 is lower than that of the mass flow sensor 2, a downward bulge 106 is arranged on the inner side of the upper cover plate 102 corresponding to the position of the piezoelectric membrane 3, and the bulge 106 is used for limiting the trend of the air flow channel 103 and enabling the air flow channel 103 to be in a broken line shape, so that air flow can be buffered to a certain extent. The two ends of the piezoelectric membrane 3 are disposed on the lower substrate 101, and a vibration gap 107 is disposed between the middle of the piezoelectric membrane 3 and the lower substrate 101.
Example two
Referring to fig. 3 and 4, an MEMS mass flow controller based on a piezoelectric control valve includes a housing 1, a mass flow sensor 2, and a piezoelectric diaphragm 3; the housing 1 comprises a lower substrate 101, an upper cover plate 102 and an airflow channel 103 enclosed by the two; the mass flow rate sensor 2 is disposed on the opposite left side of the lower substrate 101, i.e., on the side close to the inlet 104 of the gas flow channel 103; the piezoelectric diaphragm 3 is disposed on the opposite right side of the lower substrate 101, i.e., the side close to the outlet 105 of the airflow channel 103, the two ends of the piezoelectric diaphragm 3 are disposed on the lower substrate 101, and a vibration gap 107 is disposed between the middle of the piezoelectric diaphragm 3 and the lower substrate 101. The mass flow sensor 2 and the upper surface of the piezoelectric diaphragm 3 are located at the same level, and the airflow passage 103 is in a horizontal linear shape.
Specifically, the housing 1 is made of a rigid material which is airtight, the lower substrate 101 and the upper substrate 102 are fixedly connected by welding, crimping, fastening, buckling and the like, and the cross-sectional shape of the airflow channel 103 is circular or polygonal; in the first and second embodiments of the present invention, the material of the housing 1 is an aluminum alloy, the lower substrate 101 and the upper substrate 102 are fixed by fastening, and the cross-sectional shape of the airflow channel 103 is rectangular.
Specifically, the mass flow sensor 2 is manufactured by an MEMS process, and is fixed on the lower substrate 101 by an adhesive method. Referring to fig. 5, in the first and second embodiments of the present invention, the mass flow sensor 2 includes:
a substrate 201 provided with a heat insulating cavity 208 which is penetrated in the vertical direction;
a support layer 202 formed on the substrate 201 and the insulating cavity 208;
a heating element 203 formed on the upper surface of the support layer 202 and partially located above the insulating cavity 208;
the temperature sensing elements 204 are formed on the upper surface of the supporting layer 202, and the two temperature sensing elements 204 are symmetrically distributed on two sides of the heating element 203 and are locally positioned above the heat insulation cavity 208;
a metal layer 205 formed on the upper surface of the support layer 208;
an insulating layer 206 covering the heating element 203, the temperature sensing element 204 and the metal layer 205, and a contact hole 207 exposing a portion of the metal layer 205 is formed on the insulating layer 206 by partial etching.
The substrate 201 is a common semiconductor substrate including, but not limited to, one of a silicon substrate, a germanium substrate, an SOI substrate, a GeOI substrate; in the first and second embodiments of the present invention, the substrate 201 is a single crystal silicon substrate polished on both sides.
The cross-sectional shape of the insulating cavity 208 includes, but is not limited to, one of rectangular, trapezoidal, and inverted trapezoidal; in the first and second embodiments of the present invention, the cross-sectional shape of the thermal insulation cavity 208 is rectangular.
The materials of the support layer 202 and the insulating layer 206 are one or two of silicon oxide and silicon nitride; in the first and second embodiments of the present invention, the supporting layer 202 is formed by compounding silicon oxide and silicon nitride, and the insulating layer 206 is made of silicon oxide.
The material of the heating element 203 is one of P-type polysilicon, N-type polysilicon and metal; in the first and second embodiments of the present invention, the material of the heating element 203 is platinum.
The temperature-sensing element 204 can be a thermistor or a thermopile; the material of the thermistor is metal with positive/negative temperature coefficients, and the material of the thermopile is a combination of P-type polycrystalline silicon/N-type polycrystalline silicon, or a combination of P-type polycrystalline silicon/metal, or a combination of N-type polycrystalline silicon/metal; in the first and second embodiments of the present invention, the temperature sensing element 32 is a P-type polysilicon/N-type polysilicon thermopile, in which the P-type polysilicon and the N-type polysilicon are connected by a portion of the metal layer 205.
The metal layer 205 is made of one or more of titanium, tungsten, chromium, platinum, aluminum and gold; in the first and second embodiments of the present invention, the material of the metal layer 205 is chromium/gold.
It should be noted that the working principle of the mass flow sensor 2 is as follows: the heating element 203 provides a certain power to make the surface temperature of the sensor higher than the ambient temperature, when no gas flows, the surface temperature is normally distributed by taking the heating element 203 as the center, and the temperature sensing elements 204 on the two sides have the same electric signal; when gas flows, the temperature distribution on the sensor surface is shifted by the heat transferred by the gas molecules, and the electric signals of the temperature sensing elements 204 on the two sides are different, so that the gas flow can be calculated by utilizing the difference.
Specifically, the piezoelectric membrane 3 is made of an inorganic piezoelectric material such as Barium Titanate (BT) and lead zirconate titanate (PZT), or an organic piezoelectric material such as polyvinylidene fluoride (PVDF), and is fixed to the lower substrate 101 by bonding or mechanical clamping; in the embodiment of the present invention, the piezoelectric diaphragm 3 is PZT-5 and is fixed on the lower substrate 101 by bonding.
The piezoelectric diaphragm 3 is a movable member of the MEMS mass flow controller of the present invention: when a voltage is applied to the upper and lower surfaces of the piezoelectric diaphragm 3, a radial tensile/compressive strain is generated in the piezoelectric diaphragm 3 due to the inverse piezoelectric effect, eventually causing the entire piezoelectric diaphragm 3 to bend, and the degree of bending depends on the magnitude of the applied voltage.
It should be noted that, the working principle of the MEMS mass flow controller based on the piezoelectric control valve of the present invention is: after gas is introduced into the housing 1 from the inlet 104 of the gas flow channel 103, the mass flow of the gas is measured by the mass flow sensor 2 and fed back to the back-end processing circuit to be compared with a given value, and then the driving voltage of the piezoelectric diaphragm 3 is dynamically adjusted by the feedback to control the bending degree of the piezoelectric diaphragm 3, namely the size of the gas flow channel, so that the gas mass flow is accurately controlled.
In summary, the MEMS mass flow controller based on the piezoelectric control valve provided by the present invention has the characteristics of simple structure, small volume and low cost, and avoids the complicated preparation process, and has strong controllability; the utility model discloses utilize MEMS mass flow sensor to carry out the precision measurement to gas flow to regard measuring voltage as the feedback quantity, be used for guiding the driving voltage who adjusts piezoelectric diaphragm, and then utilize piezoelectric diaphragm's deformation to realize the accurate control to the flow, consequently, the utility model provides a MEMS mass flow controller based on piezoelectric control valve is stable high, can realize the high accuracy measurement and the control of small flow.
Therefore, the utility model effectively overcomes various defects in the prior art and has high industrial utilization value.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (3)
1. The MEMS mass flow controller based on the piezoelectric control valve is characterized by comprising a shell, a mass flow sensor and a piezoelectric membrane, wherein the mass flow sensor and the piezoelectric membrane are positioned in the shell; the mass flow sensor is arranged on one side, close to the inlet of the airflow channel, of the lower substrate; the piezoelectric diaphragm is arranged on one side, close to the outlet of the airflow channel, of the lower substrate; the piezoelectric diaphragm is arranged on the lower substrate at two ends, and a vibration gap is arranged between the middle part of the piezoelectric diaphragm and the lower substrate.
2. A MEMS piezoelectric control valve based mass flow controller as claimed in claim 1, wherein the piezoelectric diaphragm is located lower than the mass flow sensor, and the inner side of the upper cover plate is provided with a downward protrusion corresponding to the location of the piezoelectric diaphragm.
3. A piezoelectric control valve based MEMS mass flow controller as claimed in claim 1 wherein the mass flow sensor comprises:
the substrate is provided with a heat insulation cavity which is communicated along the vertical direction;
the supporting layer is formed on the substrate and the heat insulation cavity;
the heating element is formed on the upper surface of the supporting layer and is locally positioned above the heat insulation cavity;
the temperature sensing elements are formed on the upper surface of the supporting layer, are symmetrically distributed on two sides of the heating element and are locally positioned above the heat insulation cavity;
the metal layer is formed on the upper surface of the supporting layer;
the insulating layer covers the heating element, the temperature sensing element and the metal layer, and a contact hole exposing part of the metal layer is formed on the insulating layer through local etching.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202120675603.7U CN215059956U (en) | 2021-04-01 | 2021-04-01 | MEMS mass flow controller based on piezoelectric control valve |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202120675603.7U CN215059956U (en) | 2021-04-01 | 2021-04-01 | MEMS mass flow controller based on piezoelectric control valve |
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| Publication Number | Publication Date |
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| CN215059956U true CN215059956U (en) | 2021-12-07 |
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| CN202120675603.7U Active CN215059956U (en) | 2021-04-01 | 2021-04-01 | MEMS mass flow controller based on piezoelectric control valve |
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