WO2011078715A1 - Procédé de mesure de valeurs physiques à l'aide de convertisseur piézoélectriques, et convertisseur способ измерений физических величин пьезорезистивными преобразователями и преобразователь - Google Patents

Procédé de mesure de valeurs physiques à l'aide de convertisseur piézoélectriques, et convertisseur способ измерений физических величин пьезорезистивными преобразователями и преобразователь Download PDF

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Publication number
WO2011078715A1
WO2011078715A1 PCT/RU2009/000706 RU2009000706W WO2011078715A1 WO 2011078715 A1 WO2011078715 A1 WO 2011078715A1 RU 2009000706 W RU2009000706 W RU 2009000706W WO 2011078715 A1 WO2011078715 A1 WO 2011078715A1
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Prior art keywords
plate
strain
center
rectangle
conditional
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PCT/RU2009/000706
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English (en)
Russian (ru)
Inventor
Борис Иванович ПИBOHEHKOB
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Pivonenkov Boris Ivanovisch
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Publication of WO2011078715A1 publication Critical patent/WO2011078715A1/fr

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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01LMEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00Measuring force or stress, in general
    • G01L1/18Measuring force or stress, in general using properties of piezo-resistive materials, i.e. materials of which the ohmic resistance varies according to changes in magnitude or direction of force applied to the material
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01PMEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P15/00Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
    • G01P15/02Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
    • G01P15/08Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values
    • G01P15/12Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values by alteration of electrical resistance
    • G01P15/123Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values by alteration of electrical resistance by piezo-resistive elements, e.g. semiconductor strain gauges
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01PMEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P15/00Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
    • G01P15/18Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration in two or more dimensions

Definitions

  • the claimed technical solution relates to measuring technique, namely, to methods for measuring physical quantities by piezoresistive transducers and to transducers that carry them out.
  • a known method of measuring physical quantities by piezoresistive transducers is that a concentrated (in the case of force sensors) or distributed force (pressure force in the case of pressure sensors, inertia in the case of accelerometers ... is applied to the plate (elastic element) ... ), proportional to the measured value, the plate is deformed, mechanical stresses are transmitted to the strain gauges formed in / on the plate (elastic element), and the output signal is removed from the converter strain diagram.
  • This measurement method is carried out by existing piezoresistive transducers.
  • the quality of the transducer of mechanical quantities (the set of its main characteristics: sensitivity, speed and mass of the load in the case of accelerometers; sensitivity, speed and size of the membrane in the case of pressure sensors) is determined by the deformation energy of the elastic element when measuring a value equal to the range being measured by the transducer .
  • the strain energy W is equal to:
  • k is the stiffness of the elastic element; ao - measurement range of the accelerometer;
  • soo is the natural frequency of the accelerometer.
  • the first accelerometer has 100 times less mass of the load or
  • the strain energy of the strain gages of the converter is the minimum energy that makes it possible to measure a physical quantity by it. If the strain energy of the elastic element of the transducer is close to this value, the transducer has the best basic characteristics, close to the maximum possible theoretically.
  • a known method for measuring physical quantities requires (assumes) the deformation of the entire plate (elastic element) or a significant part of it, and not just strain gauges. Therefore, the strain energy of the plate (elastic element) in the known method is many times higher than the strain energy of the strain gages themselves, and the quality of the transducers implementing the known method, i.e. the combination of their basic characteristics is many times inferior to the maximum achievable set of basic characteristics.
  • the thicknesses of stress concentrators in converters that carry out the known measurement method are reduced to values of the order of 5 ⁇ m, and their linear dimensions to values of the order of 30-50 ⁇ m. Further significant progress in this direction is almost impossible for a number of reasons:
  • the initial silicon wafers have a thickness of about 450 ⁇ m, and obtaining ultrathin stress concentrators with a small spread in thickness (which determines the sensitivity spread in the manufacture of converters and the spread in the characteristics of individual strain gauges in the converter itself) is technologically extremely difficult;
  • the oxide and metallization layers located on the surface of the plate have an increasingly negative influence on the metrological characteristics of the converters (time and temperature stability of the initial signal and sensitivity, hysteresis, etc.) and having low elastic characteristics.
  • the known measurement method and its converters do not allow providing sensitivity, speed, and small sizes close to the theoretically maximum possible.
  • the known method of measurement and its converters require a rigid periphery of the plate (elastic element) to ensure its deformation in the measurement process; in addition, the mechanical stresses generated in the strain gages during measurement must be exactly proportional to the measured value, which cannot be achieved with a small rigidity of the periphery. This does not allow to reduce the size of the plate (and hence the dimensions of the transducer as a whole) to values less than one mm.
  • piezoresistive transducers that carry out the known method of measurement [1, 3], in which a profiled plate with strain gauges located above the stress concentrators, are made of undoped or lightly doped p-type silicon of the ⁇ 100 ⁇ plane, the most widely used in microelectronics. Strain gages are formed from heavily doped p-type silicon with an orientation of the [PO] type by diffusion [1] or ion doping [3] and do not protrude above the wafer surface.
  • strain gauges are made of an epitaxial silicon film grown on sapphire.
  • strain gauges have the appearance of mesastructures and protrude above the surface of the plate.
  • the execution of strain gauges in the form of mesastructures is due only to the technology of their formation from a continuous silicon film (etching of the remaining portions of the silicon film during the formation of the strain gauge of the converter) and does not carry any additional functions.
  • the integrated silicon tensoaccelerometer [1] which carries out the known measurement method, contains an elastic element in the form of a cantilever silicon beam with a stress concentrator and diffusion tensoresistors connected to the bridge circuit located above the concentrator on the flat side of the beam, while the free end of the console is - is inertial mass.
  • a pressure transducer operating in the known manner also functions [2]. Under the influence of the measured pressure, its elastic element (non-profiled sapphire plate) is deformed, mechanical (bending) stresses ⁇ ⁇ , ⁇ ⁇ réelle , ⁇ ⁇ are transferred to the epitaxial strain gages, which leads to a change in their resistances and the appearance of a signal proportional to the measured pressure at the output of the strain circuit. . Since no force is applied to the upper surface of the strain gages, the mechanical stresses T k , T zx , T zy are equal to zero (in any if their values are negligibly small in comparison with the stresses ⁇ ,
  • the indicated technical effect is achieved by the fact that in the method of measuring physical quantities by piezoresistive transducers, which consists in the fact that the transducer is affected by a concentrated or distributed force proportional to the measured quantity, the plate is deformed, mechanical stresses are transmitted to the strain gauges formed in on the plate (elastic element) and register the output signal from the strain gauge of the transducer, exert force on the surfaces of the strain gages (at least one strain gage), ak that normal and / or shear stresses T ⁇ , T zx, T zy at deformable strain gauges (for a Z-axis perpendicular to the plane of the plate, in / on which are formed strain gages, and the axes X and Y, lying in the plane of the plate) are determining (dominant) in changing the resistance of the strain gages and the formation of the output signal, and the forces applied to individual strain gages are evenly distributed over their surface (area).
  • the point of application of the force acting on the group of deformable strain gauges can be shifted relative to the location groups of deformable strain gages, so that a bending moment acts on the group of deformable strain gages, and the result of its action is decisive (domin ruyuschim) in the variation of the resistance strain gauges and formation tenzoskhemy output signal.
  • a piezoresistive transducer implementing the inventive measurement method, comprising a plate with strain gauges formed in it (on it), above the surface of the plate from the side of the strain gauge W
  • An additional structure is located that is connected (in contact) with the surface of the strain gauges and acts on the group of strain gauges (on the surface of the strain gauges), connected (in contact) with the structure, a force proportional to the measured value, sections of the plate or / and structures bordering with strain gauges are buried, so that the strain gauges connected by their surface to the structure, or / and the parts of the structure in contact with the strain gauges, have the form of mesastructures, i.e. protrude relative to adjacent portions of the plate or / and structure.
  • the structure in order to increase the strength and stability of the transducer characteristics, can be made integral with the plate and strain gauges, i.e. . the plate itself, strain gages and the structure connected with them (or at least its lower layer adjacent to the strain gages) can be formed from one solid blank.
  • strain gages connected to the Wheatstone bridge in order to increase the sensitivity, stability of its characteristics and reduce the spread of the parameters of the strain gages, strain gages connected to the Wheatstone bridge (or differentially, i.e.
  • the half-bridge can be equally oriented parallel to each other and located at the vertices of the conditional rectangle so that two strain gages forming opposite shoulders of the bridge (for a half-bridge, the strain gage forming the half-bridge shoulder, o two strain gauges connected in series and forming the shoulder of the half-bridge) are located on one side of the rectangle at its adjacent vertices and oriented parallel to this side, and two other strain gauges (for the half-bridge, the tensor forming the adjacent shoulder of the half-bridge, or two strain gauges connected sequentially and forming the adjacent shoulder of the half-bridge) laid on the opposite side of the rectangle in a similar manner.
  • a protrusion (mesastructure) connected to the structure can be formed in the plate, for example, a rectangular one, whose center coincides with the center of the conditional rectangle, the protrusion area is substantially (several times) larger than the total area of the group of deformable strain gages, the protrusion is oriented in the same way as the conditional nth rectangle, the length of the protrusion (its size in the direction parallel to the sides of the conditional rectangle on which the strain gages are located) is significantly (several times) longer than the lengths of the sides of the conditional rectangle on which the strain gages are located, and its width is significantly (several times) less than the width of the conditional rectangle (lengths of sides without strain gages).
  • the protrusion (mesastructure) in the center of the conditional rectangle can be bifurcated and both halves are located symmetrically relative to the center of the conditional rectangle.
  • the distance from the center of the conditional rectangle to the edges of the structure in one or both directions (parallel to the sides of the conditional rectangle) can significantly (several times) exceed the width of the conditional rectangle (the length of the sides without strain gages).
  • the structure in order to provide acceleration measurements, perpendicular to the plane of the plate, the structure can be cantilever suspended on the strain gages connected (in contact) with it, the strain gages are located on one side of the center of gravity of the structure so that the sides of the conditional rectangle on which the strain gages lie are perpendicular to the straight line connecting the center the gravity of the structure and the center of the conditional rectangle, the distance from the center of gravity of the structure to the center of the conditional rectangle is not less than twice the width of the conditional rectangle (the lengths of the sides without strain gauges), and the length of the sides of the conditional rectangle on which the strain gages are located, significantly (several times) exceeds the length of the sides without strain gages.
  • the center of gravity of the structure in order to provide measurements of accelerations parallel to the plane of the plate, can be located above the center of the conditional rectangle at a distance from it (i.e. from the surface of the plate), in any case, not less than its width (the length of the sides of a conditional rectangle without strain gages), the sides of the conditional rectangle on which the strain gages are located are perpendicular to the direction along which it is measured at molar), and the length of the rectangle sides conditional on which are tenzorezitory, sub- stantially (several times) greater than the length of the sides without the strain gauges.
  • the conditional rectangle can be made in the form of a square, the center of gravity of the structure is located above the center of the square at a distance from it (then is from the surface of the plate), in any case, no less than its side, the sides of the square are oriented along the directions of the measured acceleration components, and two tensor diagrams are arranged on the plate located on two opposite sides of the square each
  • the structure can be partially or completely connected to the plate along the perimeter, thinned flexible regions are formed in the structure and / or in the plate, separating the hard region in the central part of the structure and / or the plate from its rigid perimeter, the center of the conditional rectangle located on the plate on a rigid region (or under a rigid region, if it is formed only in the structure), is removed
  • the structure in order to increase the stability of the characteristics, can be partially or completely connected to the plate along the perimeter, thinned flexible regions are formed in the structure and / or in the plate, separating the hard regions formed in the central part of the structure and / or plate are two identical symmetrical with respect to the center of the structure and the plate from each other and from the rigid perimeter, moreover, in the case of thinning flexible regions both in the structure and in the plate, they, like the hard regions in the center of the structure and / or the plate, are made of the same shape and are located one above the other, a conditional rectangle is located in each rigid region of the plate, and its center is located at a distance from the center of gravity of a rigid region as a geometric figure not less than twice the width of a conditional rectangle (lengths of sides without strain gauges), fishing rectangles are located on hard regions symmetrically to each other with respect to the center of the structure and the plate, the sides
  • FIG. Figures 1 and 2 show the coordinate system associated with the plate, the mechanical stresses generated in the plate and the strain gauges during the measurement process, the plate, the structure and one of the strain gauges connected to the structure, as well as the forces acting on the strain gauge from the side structure.
  • Figure 1 - transverse, fig. 2 is a longitudinal section of the transducer at the location of the strain gauge.
  • FIG. 3 and 4 show the implementation of the inventive piezoresistive transducer in the general case (schematically): the location of the strain gages on the plate and the possible location and direction of the force F 0 acting on the group of deformable strain gages from the structure side in the general case, and the forces F x , F Y , F z used in different versions of the converter.
  • Fig. 3 is a side view
  • fig. 4 is a plan view.
  • FIG. Figure 5 shows the construction of the transducer, in which, to increase its strength and resistance to overloads, the structure (or at least its lower layer adjacent to the strain gauges), the plate, and the strain gauges are formed from one solid billet.
  • FIG. Figures 6 and 7 show the design of the transducer, in which, in order to increase its strength and resistance to overloads, a protrusion (integral) in contact with the structure is formed in the center of a conditional rectangle in the plate: solid (Fig. 6) or bifurcated (Fig. 7).
  • W a protrusion in contact with the structure is formed in the center of a conditional rectangle in the plate: solid (Fig. 6) or bifurcated (Fig. 7).
  • FIG. Figures 8 and 9 show the design of the transducer (accelerometer) in the case of measuring acceleration perpendicular to the plane of the plate, as well as the structure (extended horizontally along the X and Y axes), which increases the strength and stability of the transducer to overloads.
  • FIG. 8 is a plan view
  • FIG. 9 is a side view.
  • FIG. 10 and 1 1 show the design of the transducer (accelerometer) in the case of measuring one acceleration component parallel to the plane of the plate.
  • Figure 10 is a top view
  • FIG. 11 is a side view.
  • FIG. 12 shows the design of the transducer (accelerometer) in the case of measuring two acceleration components parallel to the plane of the plate (top view).
  • FIG. 13 shows the design of the inventive transducer — a pressure sensor — with thinned areas in the structure dividing it into a rigid perimeter and a rigid region in its central part (side view).
  • FIG. 1 and 2 show: part of a piezoresistive transducer with a plate 1 of silicon ⁇ -type conductivity cut in the plane (1 11); coordinate system 2 with the X, Y axes located in the plane of the plate and the Z axis perpendicular to the plane of the plate; mechanical stresses 3, which can act on p-type conductivity strain gauges oriented in the [PO] type direction and formed in the plate 1 by ion doping (Fig. 1, 2 shows one strain gauge 4).
  • Such an orientation of the strain gages for the plane (11 1) ensures their maximum sensitivity to the force f z , which is acted upon by the structure 5 connected to (contacting) the surface of the strain gage 4.
  • the strain gage 4 to transmit force only to it, and not to the entire plate is made in the form of a mesastructure 6, i.e. protruding relative to adjacent plate regions.
  • recesses 7 are made (etched) around the strain gauge in the plate.
  • section 8 of structure 5, which transmits force to the strain gauge, is also made protruding relative to the rest of the structure surface, i.e. as W 201
  • the strain gauge 4 through the heavily doped regions 9 is electrically connected to the aluminum metallized tracks 10, isolated from the plate 3 by an oxide film 11, and together with the rest of the strain gauges (not shown in figures 1, 2) forms a bridge (or differential) circuit.
  • the transducer can be performed differently, in particular, possibly.
  • a plate and strain gauges of a different orientation for example, instead of a Si orientation plate (111), a Si orientation plate (1 10), also used in microelectronics, with the same other parameters as the type of conductivity and orientation of the strain gauges can be used); - the use of diffusion or epitaxy instead of ion doping for the formation of strain gauges;
  • the converter operates as follows.
  • structure 5 transmits a force F 0 proportional to the quantity being measured (the force can be transferred to the structure itself from the transducer element that takes in the physical quantity or can be formed by the structure itself if it is a perceiving element: a membrane in the pressure transducer or inertial mass in the acceleration converter), on the upper surfaces of the group of strain gauges with which it is connected (in contact).
  • F 0 proportional to the quantity being measured
  • the force can be transferred to the structure itself from the transducer element that takes in the physical quantity or can be formed by the structure itself if it is a perceiving element: a membrane in the pressure transducer or inertial mass in the acceleration converter), on the upper surfaces of the group of strain gauges with which it is connected (in contact).
  • different forces act on different strain gages, the magnitude and direction of which are determined by the magnitude and direction of the force Fo applied to the structure, and the relative position of the point of application of the force Fo to the structure and the group
  • the strain gauge 4 is affected by a force f z uniformly distributed over its surface (area), which creates a mechanical stress T ⁇ in the volume of the strain gauge T ⁇ equal to f z / S, where S is the surface area of the strain gauge.
  • T ⁇ the mechanical stress in the volume of the strain gauge T ⁇ equal to f z / S
  • S the surface area of the strain gauge.
  • the output signal of the transducer depends on the magnitude of the mechanical stresses (in the strain gauges), which in the transducer under consideration in each strain gauge are determined by the force acting on it and the surface area of the strain gauge that is well reproduced in the manufacture of the transducer (up to tenths of a percent).
  • the converters carrying out the claimed measurement method will have, in contrast to the known converters, high reproducibility of sensitivity.
  • the strain energy of the transducer is minimal, which ensures high basic characteristics (see the beginning of the description).
  • the changes in the resistance values of the strain gauges in adjacent arms be opposite in sign. This is achieved when the stresses in the strain gages in adjacent arms are the same, but the strain gages of the strain gages have a different sign, or when the strain gages of the strain gages are the same, and the stresses in the strain gages are opposite.
  • the coefficient of sensitivity to k is the same for all directions of the [PO] type.
  • the force Fo may not be enough to create the necessary magnitudes of the mechanical stresses in the resistors.
  • FIG. Figures 3 and 4 show a piezoresistive transducer including a plate 1 with tensor resistors 12 and 13 centered on it (strain gauges 12 and 13 form adjacent shoulders of the bridge, two strain gauges W
  • resistors 12 lie on opposite shoulders of the bridge, in the same way as two tensor resistors 13), equally oriented parallel to each other and located at the vertices of the conditional rectangle 14 so that two tensor resistors 12 (for the half-bridge the strain gage forming the shoulder of the half-bridge or two strain gages connected in series and forming the shoulder of the half-bridge) lie on one side of the rectangle at its adjacent vertices and are oriented parallel to this side, and two strain gages 13 (for the half-bridge, the strain gauge forming the other shoulder half-bridge, or two tensor zorezistora connected in series and forming a shoulder adjacent half-bridge) are disposed on the opposite side of the rectangle 14 in a similar manner.
  • the strain gauges can be located differently than in the above-described specific embodiment.
  • the converter operates as follows.
  • structure 5 transmits a force Fo proportional to the quantity being measured and shifted horizontally relative to the center of the conditional rectangle 15 (the center of the region of the group of deformable strain gages) along the X axis on Lo> b (b is the length of the sides of the conditional rectangle without strain gages), on the upper surfaces of the group of strain gages (12 and 13) with which it is connected (in contact).
  • Fo F z .
  • the effect of the force F z displaced relative to the center of the conditional rectangle 15 by a distance L z is equivalent to the action of the force F z applied to the center of the conditional rectangle and the moment of force M:
  • the resistance of the strain gauges 12 and 13 will change in the opposite directions by about one value, and a significant output signal will appear at the output of the tensor circuit (bridge).
  • the strain of strain gauges (and hence the sensitivity of the transducer) at a shifted point of application of force is L z b times greater than the strain of strain gauges (sensitivity of the transducer) when the force is applied to the center of the conditional rectangle. This (displacement of the point of application of force) allows you to increase the sensitivity of the transducer and provide its necessary value.
  • the force F 0 acts along the Y axis (the force F y in Fig. 4), and its point of application is located above the center 15 of the conditional rectangle at a distance L y with the conditional rectangle rotated 90 ° and the strain gauges located on it in comparison with those shown in FIG. . 3;
  • the force F 0 with components F 0x , F 0y , F 0z (not shown in Fig. 3) is oriented arbitrarily with respect to the axes X, ⁇ , Z, and its point is position is shifted relative to the center of the group of deformable strain gages (their center of gravity as a geometric figure) by the vector Lo with components Lo x , L 0y , Lo (see Fig. 3). In this case, it is necessary to calculate how best to position the strain gages to obtain the maximum signal for this orientation and this location of the point of application of the force Fo.
  • FIG. 5 shows a piezoresistive transducer in which the bottom layer 16 of structure 5 adjacent to the strain gauges (one strain gauge 4 is shown) is integral with the plate 1 and the strain gauges, i.e. the plate itself 1, the strain gauges and the lower layer 16 of the structure 5 connected to them, adjacent to the strain gauges, are formed from one solid piece.
  • T zzl be the ultimate mechanical stresses at the gap of the connection of the lower layer 16 of structure 5 and the strain gauge 4 if they are not made from a single piece, but in the case when they are made from one piece: Compare two converters: the first, in which the strain gages and the structure are not made from a single piece, the second from a single piece.
  • FIG. 6 shows a transducer (top view) in which in the center 15 of the conditional rectangle 14 in the plate 1 a protrusion (mesastructure) is connected (in contact) with the structure 5, for example, rectangular, symmetrical with respect to the center 15 of the conditional rectangle 14, whose area is substantially (several times) larger than the total area of the group of deformable strain gages (12 and 13), oriented in the same way as the conditional rectangle, the length of the protrusion (the length of the sides in the direction parallel to the sides of the conditional rectangle on which s gages arranged) substantially (several times) larger than the length and sides of the rectangle conditional on which strain gauges are arranged, and the projection width substantially (several times) smaller than the width b of the conditioned rectangle (length of the sides without strain gauges).
  • the protrusion repeatedly reduces the mechanical stresses in the strain gages, due directly to the force F and the moment created by the component of the force F along the Y axis, which can act on the structure (and this increases the strength of the converter), because its area is significantly larger than the area of deformable strain gages 12 and 13, and the bending stiffness along the Y axis is much greater than the stiffness of the strain gages (since the length of the protrusion is much greater than the length of the conditional rectangle).
  • the sensitivity of the convertible decrease much less (since the protrusion is located on the symmetry axis of the conditional rectangle and its width is much less than the width b of the conditional rectangle).
  • Performing a ledge rectangular is the most simple and technologically advanced, but not required.
  • the same beneficial effect is achieved with an arbitrary protrusion shape, provided that the remaining requirements are met.
  • FIG. 8 shows a transducer (an accelerometer measuring acceleration along the Z axis), in which the distance from the center 15 of the conditional rectangle 14 to the edges of the structure in one or both directions X and Y (parallel to the sides of the conditional rectangle 14) significantly (several times) exceeds the width b of the conditional rectangle (the length of the sides without strain gauges), i.e. L ⁇ , L ⁇ , L yl , Ly 2 is several times larger than b.
  • a transducer an accelerometer measuring acceleration along the Z axis
  • the microgap ⁇ between the structure 5 and the plate 1 at the edges of the structure 5 is chosen to be larger than the displacement of the end of the structure 5 under the action of the acceleration wo equal to the measurement range of the accelerometer, but smaller than the displacement of the end of the structure 5 achieved by the acceleration w p leading to destruction of strain gauges or their connection with structure 5, i.e. the edge of the structure 5 touching the plate 1 occurs under the action of the acceleration w Kac :
  • the structure 5 is asymmetric, its left part is bifurcated, so the center of gravity of the structure 5 is shifted relative to the center 15 of the conditional rectangle 14 by a distance L z along the X axis, and the value of L z is not less than twice the width b of the conditional rectangle, and the length of the sides of the conditional rectangle on which the strain gauges are located, significantly (several times) more than the length of the sides without the strain gauges.
  • S is the surface area of one strain gauge
  • the shift of the center of gravity of the structure 5 to the right of the conditional rectangle 14 can be ensured by placing an additional load on the right side of the structure 5 (made using the technology of thin and / or thick films).
  • the perpendicularity of the sides of the conditional rectangle on which the strain gages lie, the straight line connecting the center of gravity of the structure and the center of the conditional rectangle, provides the maximum sensitivity of the converter to accelerations along the Z axis and zero sensitivity of the converter to accelerations along the Y axis.
  • the deformations of the strain gauges 12 and 13, which are opposite one another, under the action of acceleration along the Y axis will be equal to to which the output signal of the converter does not change, i.e. zero transverse sensitivity to acceleration along the Y axis will be ensured.
  • the force moment F x that arises and acts on the strain gages will be much less than the moment acting on the strain gages when the same acceleration is applied along the Z axis, since the shoulder of the force F x is much smaller than the force shoulder Fo. Therefore, the sensitivity of the transducer to accelerations along the X axis will be much less than the sensitivity to accelerations along the Z axis.
  • transducer strength is achieved with the simultaneous application of the structural and technological solutions described above and shown in Figures 5–9, namely, the implementation of the structure, strain gages and plates from one workpiece, the formation of a protrusion (mesastructure) connected to the plate in the center structure of the conditional structure performing a structure extended in the plane of the plate, so that its transverse dimensions are much larger than the width of the conditional rectangle.
  • FIG. 10 shows a transducer measuring acceleration w x (an accelerometer measuring acceleration along the X axis parallel to the plane of the plate).
  • w x an accelerometer measuring acceleration along the X axis parallel to the plane of the plate.
  • the center of gravity of the structure 5 is located above the center 15 of the conditional rectangle 14 at a distance L x from it (i.e., from the plate surface), in any case, not less than its width b, and the sides of the conditional rectangle on which the strain gages are located perpendicular to the direction along which acceleration is measured.
  • m is the mass of the load (mass of structure 5),
  • T zx F 0/4 S
  • S is the surface area of one strain gauge
  • m is the mass of the load (structure 5).
  • the output signal also does not change, because the moment M is equal to zero, and the action of the force Fo causes an identical change in the resistances of the strain gages 12 and 13.
  • the described design provides zero transverse sensitivity of the transducer (accelerometer).
  • FIG. 12 shows a transducer (biaxial accelerometer), which simultaneously measures the acceleration w x and w y (top view), in which the conditional rectangle 14 is made in the form of a square, and on the plate 1 two tensor diagrams located on two opposite sides are formed each rectangle (square) each: a strain gauge that measures w x from the strain gauges 12 on the left side of the square and the strain gauge Store 13 on the right; a strain gauge measuring w y from strain gauges 19 on the upper side of the square and strain gauges 20 on the lower.
  • the structure 5 is made symmetrical with respect to the X and Y axes, so that its center of gravity is located above the center 15 of the rectangle (square) 14 at a distance L greater than the side of the square.
  • the output tenzoskhemy measuring the w x there is an output signal proportional to w x.
  • the strain gauges 19 and 20 experience approximately equal mechanical stresses, opposite in sign, at the output of the strain gauge measuring w y , an output signal proportional to y arises.
  • FIG. 13 shows a transducer (absolute pressure sensor, side view), in which the composite structure 5, consisting of a lower layer made integrally with strain gauges 12 and 13 and plate 1, and an upper layer 21 (polyamide film), glued to the lower one, is hermetically sealed connected by the upper layer 21 to the plate 1 along the perimeter 22, and the inner cavity is evacuated.
  • the composite structure 5 consisting of a lower layer made integrally with strain gauges 12 and 13 and plate 1
  • an upper layer 21 polyamide film
  • the conditional rectangle is located at one of the edges of the rigid region so that the center 15 of the conditional rectangle is at a distance L from the center of gravity 25 of the rigid region as a geometric figure not less than twice the width b of the conditional rectangle (the length of the sides without strain gauges): L> 2b.
  • a force F 0 proportional to the pressure will act on the structure 5. Its value depends on the ratio of the stiffnesses of the central, rigid region of the structure 5 and the flexible regions 23, as well as on the fraction of the area occupied by the rigid region 24. With a low rigidity of the flexible regions 23 and a large fraction of the area occupied by the rigid region 24 in comparison with area of flexible regions, the point of application of the force Fo practically coincides with the center of gravity 25 of the rigid region as a geometric figure.
  • An embodiment of a pressure sensor providing symmetrical loading of the strain gages 12 and 13 of the strain circuit is the implementation of a rigid region in the center of the structure or / and plate divided flexible, thinned regions into two identical hard regions symmetrical relative to the center of the structure and the plate, with conditional rectangles containing two or four strain gages located symmetrically on the hard regions at the edges of the hard regions so that the center of the conditional rectangle is at a distance L from the center of gravity of a rigid region as a geometric figure not less than twice the width b of the conditional rectangle (the length of the sides without strain gauges), and the resistors in different hard regions, located symmetrical with respect to the center of the structure and plate, form opposite shoulders of the bridge (one half-bridge arm).
  • the operation of the transducer is similar to the operation of the absolute pressure transducer discussed above.
  • the inventive method of measuring physical quantities by piezoresistive transducers, providing a strain energy of the transducer close to the strain energy of the strain gauges, and the transducers implementing it, have fundamental advantages in comparison with the known method and the transducers implementing it and provide:

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Pressure Sensors (AREA)

Abstract

L'invention concerne un procédé de mesure dans lequel une force proportionnelle à la valeur à mesurer est appliquée directement à la surface supérieure de piézorésistances, tandis que le point d'application de celle-ci est déplacé par rapport aux piézorésistances de sorte qu'un couple de courbure s'exerce sur elles et possède une action prédéterminée dans la formation du signal de sortie du convertisseur. L'invention concerne un convertisseur permettant de mettre en œuvre ce procédé, qui comprend une plaque sur laquelle sont formée des piézorésistances, ainsi qu'une structure supplémentaire connectée à la surface des piézorésistances et agissant sur leur surface par l'application d'une force, convertisseur dans lequel des sections de la plaque et de la structure bordant les piézorésistances se présentent sous forme de mésastructures. L'invention concerne également des solutions structurelles pour le convertisseur, qui assurent une augmentation de sa résistance, ainsi que des mesures d'accélérations (perpendiculaires ou parallèles au plan de la plaque, y compris sur deux axes) et de pression. Le procédé de mesure et les convertisseurs pour sa mise en œuvre permettent d'obtenir des caractéristiques de base plus importantes (y compris la possibilité de réduire les dimensions du convertisseur à quelques dizaines de microns), une perte minimale de sensibilité et une fabrication industrielle simplifiée ainsi qu'une compatibilité avec les techniques de fabrication de circuits d'amplification et de traitement de signaux. Предложен способ измерений, в котором силу, пропорциональную измеряемой величине, прикладывают непосредственно к верхней поверхности тензорезисторов, а точку ее приложения смещают относительно тензорезисторов, так что на них действует изгибающий момент, воздействие которого является определяющим в формировании выходного сигнала преобразователя. Предложен преобразователь, осуществляющий заявляемый способ, содержащий пластину со сформированными в ней тензорезисторами и дополнительную структуру, соединенную с поверхностью тензорезисторов и действующую на их поверхность силой, в котором участки пластины и структуры, граничащие с тензорезисторами, выполнены в виде мезаструктур. Предложены и описаны конструктивные решения преобразователя, обеспечивающие повышение его прочности, измерение ускорений (перпендикулярных плоскости пластины или параллельных ей, в том числе по двум осям) и давления. Предложенный способ измерений и осуществляющие его преобразователи обеспечивают: - более высокие основные характеристики (включая возможность уменьшения размеров преобразователя до нескольких десятков микрон); - минимальный разброс чувствительности; - более простую технологию изготовления и её совместимость с технологией изготовления схем усиления и обработки сигнала.
PCT/RU2009/000706 2009-12-22 2009-12-22 Procédé de mesure de valeurs physiques à l'aide de convertisseur piézoélectriques, et convertisseur способ измерений физических величин пьезорезистивными преобразователями и преобразователь WO2011078715A1 (fr)

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RU2009147327/28A RU2009147327A (ru) 2009-12-22 2009-12-22 Способ измерений физических величин пьезорезистивными преобразователями и преобразователь
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116592753A (zh) * 2023-05-31 2023-08-15 秦皇岛市北戴河兰德科技有限责任公司 一种测量大型结构应力应变的温度自适应式测量装置

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4550612A (en) * 1983-05-31 1985-11-05 Hitachi, Ltd. Integrated pressure sensor
SU1303856A1 (ru) * 1985-02-11 1987-04-15 Специальное Конструкторское Бюро По Приборостроению Преобразователь давлени
RU1791782C (ru) * 1989-12-11 1993-01-30 Научно-исследовательский институт измерительной техники Полупроводниковый интегральный тензоаксельрометр
US5773728A (en) * 1995-03-31 1998-06-30 Kabushiki Kaisha Toyota Chuo Kenkyusho Force transducer and method of fabrication thereof
RU2247342C1 (ru) * 2003-08-11 2005-02-27 Криворотов Николай Павлович Мультипликативный микроэлектронный датчик давления (варианты)
JP2008051820A (ja) * 2007-09-26 2008-03-06 Toyota Central R&D Labs Inc 半導体装置

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4550612A (en) * 1983-05-31 1985-11-05 Hitachi, Ltd. Integrated pressure sensor
SU1303856A1 (ru) * 1985-02-11 1987-04-15 Специальное Конструкторское Бюро По Приборостроению Преобразователь давлени
RU1791782C (ru) * 1989-12-11 1993-01-30 Научно-исследовательский институт измерительной техники Полупроводниковый интегральный тензоаксельрометр
US5773728A (en) * 1995-03-31 1998-06-30 Kabushiki Kaisha Toyota Chuo Kenkyusho Force transducer and method of fabrication thereof
RU2247342C1 (ru) * 2003-08-11 2005-02-27 Криворотов Николай Павлович Мультипликативный микроэлектронный датчик давления (варианты)
JP2008051820A (ja) * 2007-09-26 2008-03-06 Toyota Central R&D Labs Inc 半導体装置

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116592753A (zh) * 2023-05-31 2023-08-15 秦皇岛市北戴河兰德科技有限责任公司 一种测量大型结构应力应变的温度自适应式测量装置

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