CN100403032C

CN100403032C - Capictance athermal flow-speed sensor based on micro mechanical technology

Info

Publication number: CN100403032C
Application number: CNB2006100406006A
Authority: CN
Inventors: 秦明; 魏泽文; 黄庆安
Original assignee: Southeast University
Current assignee: Southeast University
Priority date: 2006-05-29
Filing date: 2006-05-29
Publication date: 2008-07-16
Anticipated expiration: 2026-05-29
Also published as: CN1851471A

Abstract

The present invention relates to a capictance athermal flow-speed sensor based on micro mechanical technology, which is a sensor utilizing an impeller wheel processed by MEMS technology to detect a flow speed. The sensor is composed of a glass base plate (1), a silicon top cover (2), a rotating shaft (3), a rotary disc (4), an impeller wheel (5) and a capacitance polar plate (6), wherein the rotating shaft (3) is fixed to the glass base plate (1), and the upper part of the rotating shaft (3) is provided with the silicon top cover (2). The outer side of the rotating shaft (3) is sheathed with the rotary disc (4) of which the outer side is fixed with the impeller wheel (5), and the capacitance polar plate (6) is arranged on the upper surface of the glass base plate (1); the impeller wheel (5) and the rotating shaft (3) are N-type semiconductor silicon materials and not only can be used as movable rotating components, but also can be used as an electrode for measuring capacitance. The flow-speed sensor adopts a capacitance detecting mode and has the advantages of small power consumption, large linear range, rapid response, small temperature shift, good reliability, etc.

Description

Capictance athermal flow-speed sensor based on micro mechanical technology

Technical field

The present invention relates to a kind of micromechanics (MEMS) Athermal flow speed sensor, especially a kind of impeller of the MEMS of utilization technology processing detects the sensor of flow velocity.

Background technology

Fluid measurement all has important use in departments such as industrial and agricultural production, meteorology, environmental protection, national defence, scientific research, aviations, and wherein flow rate and direction is measured as ingredient important in the fluid measurement, has developed a lot of years.Measuring methods such as vane and weathervane measurement, pitot tube measurement, float measurement, mechanical meaurement, acoustic measurement, optical measurement, thermal conduction study measurement, electromagnetic measurement have successively appearred.It is little to have a volume based on the miniature current velocity flow direction sensor of MEMS process technology, and price is low, and the characteristics of good product consistency are the focuses of fluid sensor research in recent years.Van Putten has proposed first flow sensor based on silicon micromachining technology (Putten V in 1974, Middelheok S " Integrated silicon anemometer " Electron Lett., 1974 (21) .425-426), the principle of work of this sensor is based on thermal conduction study, promptly changes by the mobile thermal field that causes of measurement fluid and comes measurement flow rate to flow to information.Through the development in surplus 30 years, the hot type microfluid sensor became main flow now, particularly in the wind gage field.But the hot type microfluid sensor also has its intrinsic shortcoming.For example power consumption heat conduction big, substrate causes measuring error, zero point with environment temperature drift, response time length etc.In addition, because want convection cell heating, so just limited the application of hot type microfluid sensor aspect biological.Non-hot type microfluid sensor then can overcome above-mentioned shortcoming.Kersjes has proposed to measure method (the Kersjes R of pressure reduction, Eichholz J, Langerbein A, et al " An Integrated sensor for invasiveblood-velocity measurement " Sensors and Actuators A, 1993,37 (38) .674-678), Oosterbroek has proposed to measure method (the Oosterbroek E of pressure drop, Lammerink J, Berenschot W, et al " Design; realization and characterization of novel capacitive pressure/flow sensor " Proc.Transducers ' 97,1997.151-154), Svedin proposed to measure method (the Svedin N of lift, Stemme E, Stemme G " A new bi-directional gas flow sensor based on lift force " ProcTransducers ' 97,1997145-148), Ng proposed to measure method (the Ng K of viscous force, Shajii K, SchmidtM A " A liquid shear stress sensor fabncated using wafer bonding technology " .Proc.Transducers ' 91,1991931-934).At present, be exactly the little and energy measurement two dimension wind direction not of range based on the common shortcoming of the flow speed and direction sensor of non-hot type principle.

Summary of the invention

Technical matters: the purpose of this invention is to provide a kind of Capictance athermal flow-speed sensor based on micro mechanical technology, this flow sensor adopts capacitance detecting mode, has that power consumption is little, the range of linearity big, response is fast, temperature is floated little and advantage such as good reliability.

Technical scheme: the present invention is the vane type flow sensor that is used to measure the rate of flow of fluid signal, and this sensor comprises: glass chassis, silicon top cover, rotating shaft, rotating disk, impeller, metal polar plate and lead-in wire; On the glass chassis, be fixed with rotating shaft, be provided with the silicon top cover, be with rotating disk, be fixed with impeller, depositing metal pole plate on the glass chassis of wheel bottom correspondence in the outside of rotating disk in the outside of rotating shaft on the top of rotating shaft; The material of described rotating shaft, rotating disk and impeller is the N-type semiconductor silicon of conduction; Movable rotating disk and impeller utilize bonding techniques to form.Impeller and rotating shaft material are the N-type semiconductor silicon of conduction, and at the depositing metal electrode on glass of wheel bottom correspondence, the impeller of metal electrode and conduction itself constitutes electric capacity.When fluid acted on impeller, the fluid impeller was rotated, and impeller also rotates with respect to electrode on glass, like this, will make the capacitance size between impeller and the electrode above the glass produce the rule variation.By measuring the frequency that changes, just can obtain the speed of wheel rotation, thereby obtain flow rate information.Promptly utilize the frequency change of electric capacity to measure fluid the rotation that the acting force of impeller causes is obtained flow rate information, its manufacture method is to utilize bonding techniques to form movable rotating disk and impeller.

Beneficial effect: the present invention adopts the manufacturing of MEMS process technology, and method for making and structure are all comparatively simple, good reliability.Traditional heat type fluid sensor is by heater block is set, and allows the fluid heater block of flowing through again, measures the variation of thermal field or the temperature variation of heater block and obtains flow rate information.Owing to want the convection cell heating, power consumption is big, temperature effect is obvious.The present invention adopts mechanics principle to measure, and obtains flow rate information by the rotating speed of measuring the rotation of fluid impeller.Thereby avoided this defective.Traditional Athermal flow speed sensor utilizes bernoulli principle to measure pressure reduction or pressure drop mostly, and the range of linearity is less.The present invention is provided with impeller and solves this problem, by detecting the variation of wheel rotation speed, can obtain flow rate information.Because impeller is linear with the variation of flow velocity, so the present invention can solve the little problem of the range of linearity.The employing capacitance type structure detects, and temperature drift is little, and is highly sensitive, and antijamming capability is strong.Simultaneously, detection be the frequency size of capacitance variations rather than the order of magnitude of capacitance variations, so further improved sensitivity and antijamming capability.Utilize SOI (silicon-on-insulator) silicon chip that bonding forms as structured material, discharge by ICP (plasma enhancing etching) and sacrifice layer and form impeller and pivot structure, and then finish rotating shaft and glass bonding fixing and go between.And generally adopt first deposit LTO (low temperature silicon dioxide) or PSG (silicon dioxide of phosphorus doping) in the traditional handicraft as sacrifice layer, releasing sacrificial layer forms the gap between the impeller then, this tends to cause structure cohesion or the out-of-flatness that is released, make component failure, the present invention adopts the soi wafer technology will overcome this defective, has strengthened the reliability of sensor greatly.

Description of drawings

Fig. 1 is a structural representation of the present invention.

Fig. 2 is the sectional view of the present invention along the A-A direction.

Have among the above figure: glass chassis 1, silicon top cover 2, rotating shaft 3, rotating disk 4, impeller 5, capacitor plate 6.

Embodiment

The present invention is a kind of sensor of measuring rate of flow of fluid with blade wheel structure.By glass chassis 1, silicon top cover 2, rotating shaft 3, rotating disk 4, impeller 5 and capacitor plate 6 and lead-in wire are formed.Rotating shaft 3 is to link together by bonding technology and chassis and top cover.The material of rotating shaft 3, impeller 5 and rotating disk 4 is the N-type semiconductor silicon of conduction, obtains by two-sided three corrosion, and the glass surface depositing metal pole plate 6 of correspondence below each impeller 5, impeller 5 itself conducts electricity, and becomes another piece pole plate.Constitute electric capacity between the impeller 5 of conduction and the metal polar plate 6.Impeller 5 relies on 1 lead-in wire from the glass chassis that contacts of rotating disk 4 and rotating shaft 3.When fluid is flowed through impeller 5, can impeller 5 rotations.Make the overlapping area of impeller 5 and glass chassis 1 upper metal pole plate 6 that size variation clocklike take place.The frequency and the flow velocity that change are directly proportional.So,, just can obtain the information of flow velocity by measuring electric capacity by greatly changing to minimum frequency.

The manufacturing process of this ratio sensor is: prepare N-type semiconductor silicon chip 1# and 2#; Oxidation 1# and 2# and bonding form soi wafer; Etching 1# forms the step of rotating disk 4; Etching 1# forms the step of impeller 5; ICP etching 1# forms rotating shaft 3, rotating disk 4 and impeller 5; Glass 1 splash-proofing sputtering metal forms capacitor plate 6 and lead-in wire; Glass and N-type semiconductor silicon chip 1# bonding; Corrosion of silicon 2# forms top cover; Sacrifice layer discharges and forms rotating impeller 5 and rotating disk 4.

Claims

1. Capictance athermal flow-speed sensor based on micro mechanical technology, this sensor comprise glass chassis (1), silicon top cover (2), rotating shaft (3), rotating disk (4), impeller (5), metal polar plate (6) and lead-in wire; On glass chassis (1), be fixed with rotating shaft (3), be provided with silicon top cover (2) on the top of rotating shaft (3), be with rotating disk (4) in the outside of rotating shaft (3), be fixed with impeller (5), go up depositing metal pole plate (6) on the glass chassis (1) that impeller (5) bottom is corresponding in the outside of rotating disk (4); The material of described rotating shaft (3), rotating disk (4) and impeller (5) is the N-type semiconductor silicon of conduction; Movable rotating disk (4) and movable impeller (5) utilize bonding techniques to form.