CN106918380B - A kind of micro- quality detecting method of high sensitivity and portable quality test device - Google Patents
A kind of micro- quality detecting method of high sensitivity and portable quality test device Download PDFInfo
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- CN106918380B CN106918380B CN201710086715.7A CN201710086715A CN106918380B CN 106918380 B CN106918380 B CN 106918380B CN 201710086715 A CN201710086715 A CN 201710086715A CN 106918380 B CN106918380 B CN 106918380B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01G—WEIGHING
- G01G3/00—Weighing apparatus characterised by the use of elastically-deformable members, e.g. spring balances
- G01G3/12—Weighing apparatus characterised by the use of elastically-deformable members, e.g. spring balances wherein the weighing element is in the form of a solid body stressed by pressure or tension during weighing
- G01G3/14—Weighing apparatus characterised by the use of elastically-deformable members, e.g. spring balances wherein the weighing element is in the form of a solid body stressed by pressure or tension during weighing measuring variations of electrical resistance
- G01G3/142—Circuits specially adapted therefor
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Abstract
The invention discloses a kind of micro- quality detecting method of high sensitivity and portable quality test devices, micro- quality detecting method are as follows: with a certain specific frequency in a certain range before and after micro-mass sensor resonance frequency be detection frequency, the forward and backward micro-mass sensor equivalent circuit impedance differences of load mass are measured in the case where detecting frequency, and difference is converted to micro- quality of load by calculating.The portable quality test device that declines of adopting said method includes micro-mass sensor, signal generating module and impedance read module, and the micro-mass sensor is piezoelectric cantilever sensor.Measurement method of the present invention improves 100 times or more relative to frequency measurement sensitivity; measuring principle is simple; required equipment price is cheap; portability is strong, thus can be widely used for air-borne dust pollution, environmental pollution, harmful influence leakage and the accurate measurement of the Tiny Mass such as microorganism such as bacterium or virus.
Description
Technical field
The present invention relates to portable detection sensor technical field, specifically a kind of micro- quality detecting method of high sensitivity
And portable quality test device.
Background technique
Piezoelectric cantilever type micro-mass sensor is a kind of novel sensor for integrating excitation, sensing, is answered extensively
For fields such as air-borne dust, the detection of microbial pathogens and identifications.Piezoelectric cantilever sensor is by piezoelectric membrane and elasticity member
Part two parts composition.
Currently, the measurement of micro- quality is mainly realized by the method for frequency offset detection, its working principle is that by detecting area
The Tiny Mass variation of absorption is converted into the variation of resonance frequency, derives that micro- quality becomes according to the difference on the frequency before and after quality of adsorption
Change, i.e. Δ m=- Δ f Me/fn, wherein fn is the structural resonance frequency of corresponding n-th order mode, and Me is cantilever beam equivalent mass,
Δ m is detected amount of substance, and Δ f is resonance frequency variable quantity.A large amount of prior arts are based on frequency-difference method, for example, the U.S. is special
Sharp 6389877 B1 of US, WO 2005/043126 country A2 patent CN1250156A, CN2011101177772,
CN201110216323.0, ZL2013100145951, ZL2013103177028 etc. are by measuring different cantilever designs
Difference on the frequency identifies Tiny Mass.In addition, document " Higher modes of vibration increase mass
Sensitivity in nanomechanical microcantilevers " and " An alternative solution to
improve sensitivity of resonant microcantilever chemical sensors:comparison
Between using high-order modes and reducing dimensions " can according to frequency-difference method measuring principle
Know, needs just to can determine that difference on the frequency caused by micro- mass change by a certain range of sweep measurement.By measuring high frequent vibration
The difference on the frequency of mode identifies Tiny Mass.The micro- quality of frequency offset detection.It should be noted that frequency-difference method is in practical application
In there are clearly disadvantageous, i.e. its micro- quality sweep measurement process based on frequency difference depends critically upon impedance analyzer, and impedance
Analyzer it is expensive, and measurement accuracy is influenced by instrument and environmental damping by quality factor and resolution ratio, frequency sweep survey
Amount process is complicated.
In order to simplify measurement process and promote micro- quality detection sensitivity, needing a kind of more effective and being easier realization
Micro- mass measuring method, it is micro- to meet air-borne dust pollution, environmental pollution, harmful influence leakage and microorganism such as bacterium or virus etc.
The accurate measurement demand of small quality.
Summary of the invention
It declines deficiency existing for quality determining method for traditional frequency difference, it is quasi- the invention aims to provide a kind of detection
Really, using a kind of convenient micro- quality detecting method of high sensitivity.
To achieve the goals above, technical solution of the present invention is as follows:
A kind of micro- quality detecting method of high sensitivity, it is characterised in that: with certain before and after micro-mass sensor resonance frequency
A specific frequency is detection frequency in range, by the forward and backward micro-mass sensor impedance variations of load mass, is obtained by calculation and adds
The micro- quality size carried, step include:
It S1, take a specific frequency in a certain range before and after micro-mass sensor vibration frequency as detection frequency, measurement load matter
Measure forward and backward detection circuit output voltage；
S2, the variation for calculating output voltage obtain the forward and backward micro-mass sensor impedance of load mass by calculation process and become
Change；
S3, according to the linear relationship under the detection frequency between micro-mass sensor impedance variations and load mass, pass through
Load mass size is calculated.
It is another object of the present invention to provide a kind of portable quality test dress that declines based on above-mentioned quality detecting method
It sets, micro- quality test device includes micro-mass sensor, signal generating module, detection circuit and impedance read module；
The micro-mass sensor is piezoelectric cantilever sensor comprising fixed block, the cantilever beam for being connected to fixed block
Be pasted on the piezoelectric patches wide on cantilever beam and with cantilever beam, the piezoelectricity leaf length is less than cantilever beam length, the cantilever
Beam and piezoelectric patches are bonded cantilever beam and piezoelectric patches composite log, and cantilever beam is not cantilever beam extension with piezoelectric patches bound fraction
Section；
The signal generating module includes signal generating circuit and power amplifier, the power amplifier output end and institute
State micro-mass sensor piezoelectric patches lead-out wire connection, the piezoelectric patches connect with resistance R after with additional capacitor CpIt is in parallel；
The impedance read module parallel connection and additional capacitor CpBoth ends.
Further, each rank resonance frequency of the micro-mass sensor is
Wherein,For the cantilever beam and piezoelectric patches composite log amplitude function；For the cantilever beam extended segment
Amplitude function；l1For cantilever beam and the compound segment length of piezoelectric patches；l2Extend segment length for cantilever beam；m1=(ρptp+ρnptnp)w；m2=
ρnptnpw；EpFor the elasticity modulus of the piezoelectric patches；tpFor the thickness of the piezoelectric patches；ρpFor the density of the piezoelectric patches；EnpFor
The elasticity modulus of the cantilever beam；tnpFor the thickness of the cantilever beam；ρnpFor the density of the cantilever beam；W is the piezoelectric patches
With the width of the cantilever beam.
Further, by adjusting additional capacitor CpThe adjusting of realization device range and device measurement sensitivity.
Further, described by adjusting additional capacitor CpRealize the device measurement sensitivity adjusted are as follows:
Wherein, RmFor piezoelectric cantilever sensor dynamic electric resistor, CmFor piezoelectric cantilever sensor dynamic capacity, LmFor pressure
Electric cantilever beam sensor dynamic inductance, ωnFor input voltage frequency, CpFor additional capacitor, Δ m is load mass.
Compared with prior art, beneficial effects of the present invention:
1, the present invention demonstrates the feasibility of impedance measurement method, sensitivity is compared to same structure from point of theory
Frequency measurement improves 100 times or more.
2, the present invention devises new measuring circuit from portability angle, and complicated frequency measurement is changed to simplicity
Resistance measurement, measuring device volume is small, and portability is strong, cheap.
3, the present invention is not by changing sensor structure to the method for the series-parallel additional circuit of piezoelectric cantilever sensor
And sensor measurement range and measurement sensitivity are adjusted in the case where size.
Detailed description of the invention
In order to more clearly explain the embodiment of the invention or the technical proposal in the existing technology, to embodiment or will show below
There is attached drawing needed in technical description to be briefly described, it should be apparent that, the accompanying drawings in the following description is this hair
Bright some embodiments for those of ordinary skill in the art without any creative labor, can be with
It obtains other drawings based on these drawings.
Fig. 1 is quality detecting method flow chart of the present invention.
Fig. 2 is piezoelectric cantilever sensor structure chart of the present invention；
Fig. 3 is the portable apparatus for measuring quality detection circuit schematic diagram that declines of the present invention；
Fig. 4 is the portable apparatus for measuring quality schematic diagram that declines of the present invention；
Fig. 5 is 1 impedance variations curve of embodiment；
Fig. 6 is the portable apparatus for measuring quality curve that declines of 2 impedance variations of embodiment；
Fig. 7 is 3 impedance variations curve of embodiment；
Drawing reference numeral explanation:
1, fixed block, 2, piezoelectric patches, 3, cantilever beam.
Specific embodiment
In order to make the object, technical scheme and advantages of the embodiment of the invention clearer, below in conjunction with the embodiment of the present invention
In attached drawing, technical scheme in the embodiment of the invention is clearly and completely described, it is clear that described embodiment is
A part of the embodiment of the present invention, instead of all the embodiments.Based on the embodiments of the present invention, those of ordinary skill in the art
Every other embodiment obtained without creative efforts, shall fall within the protection scope of the present invention.
As sensor input voltage UiFrequency fiFor each rank resonance frequency fnNeighbouring a certain range of a certain specific frequency
When, impedance changes with frequency approximately linear, and the size of load mass can be obtained by impedance variations before and after load mass.
Based on the above principles, the present invention provides a kind of micro- quality detecting methods of high sensitivity, which is characterized in that with micro- matter
A certain specific frequency is detection frequency in a certain range before and after quantity sensor resonance frequency, is passed by the forward and backward micro- quality of load mass
Micro- quality size of load is obtained by calculation in sensor equivalent circuit impedance variations, and testing process is as shown in Figure 1, step packet
It includes:
S1, take a certain specific frequency in a certain range before and after micro-mass sensor resonance frequency as detection frequency, measurement plus
The forward and backward detection circuit output voltage of mounted mass.The specific detection frequency is generally debugged before equipment factory, when use
It is not required to carry out additional frequency modulation work.Sensor resonant frequency used in the present embodiment are as follows:
Wherein,For the cantilever beam and piezoelectric patches composite log amplitude function；For the cantilever beam extended segment
Amplitude function；l1For cantilever beam and the compound segment length of piezoelectric patches；l2Extend segment length for cantilever beam；m1=(ρptp+ρnptnp)w；m2=
ρnptnpw；EpFor the elasticity modulus of the piezoelectric patches；tpFor the thickness of the piezoelectric patches；ρpFor the density of the piezoelectric patches；EnpFor
The elasticity modulus of the cantilever beam；tnpFor the thickness of the cantilever beam；ρnpFor the density of the cantilever beam；W is the piezoelectric patches
With the width of the cantilever beam.
It is poor by the forward and backward micro- matter sensor impedance of load mass that S2, the variation for calculating output voltage are obtained by calculation process.
S3, according to the linear relationship under the detection frequency between impedance and load mass, load mass is obtained by calculation
Size.
The present embodiment provides a kind of portable quality test device that declines based on above-mentioned quality detecting method, micro- quality
Test device includes micro-mass sensor, signal generating module, detection circuit and impedance read module；
The micro-mass sensor be piezoelectric cantilever sensor, the piezoelectric cantilever sensor structure as shown in Fig. 2,
It includes being connected to the cantilever beam 3 of fixed block 1, and the piezoelectric patches 2 being pasted on cantilever beam 3, the cantilever beam are selected high-elastic
Property material, piezoelectric patches are made film-form and adhere well on cantilever beam.Wherein, piezoelectric patches 2 and cantilever beam 3 is wide and piezoelectric patches 2
Length be less than the length of cantilever beam 3, the cantilever beam and piezoelectric patches are bonded cantilever beam and piezoelectric patches composite log, cantilever beam
It is not cantilever beam extended segment with piezoelectric patches bound fraction；
The signal generating module includes signal generating circuit and the power amplifier that connect with signal generating circuit, described
Power amplifier output end is connect with the piezoelectric patches lead-out wire of the micro-mass sensor, and the piezoelectric patches and resistance R go here and there
After connection with additional capacitor CpIt is in parallel；
The impedance read module parallel connection and additional capacitor CpBoth ends, the both ends b, d load Ui=uiejωtSinusoidal input electricity
Pressure, the both ends a, c output voltage Uo。
The present embodiment uses the total impedance Z of Wheatstone bridge measurement sensor, is illustrated in figure 3 detection circuit schematic diagram,
U is loaded at the both ends bdi=uiejωtInput sinusoidal voltage, the both ends ac output voltage Uo.When bridge balance, electric bridge opposing arms resistance
Product it is equal, i.e. ZR3=R2R4.It can cause the variation of total impedance as sensor quality of adsorption Δ m, be sensed after quality of adsorption
The total impedance of device is Z', then sensor quality of adsorption Δ m causes the change Delta Z of total impedance, by detecting output voltage UoChange
Change obtains impedance change, AZ=Δ UoZ/Ui.According to piezoelectric cantilever sensor impedance variations curve, input voltage UiFrequency
fiFor each rank resonance frequency fnWhen neighbouring a certain range of a certain specific frequency, impedance changes with frequency approximately linear, by adding
The size of load mass Δ m can be obtained in impedance change, AZ before and after mounted mass.
Piezoelectric cantilever sensor impedance Z=the Re+jXe,
Wherein: ReFor resistive component, XeFor reactive component.
It is illustrated in figure 4 the portable apparatus for measuring quality overall structure diagram that declines.
Further, by adjusting additional capacitor CpThe adjusting of realization device range and device measurement sensitivity.Work as load
When maximum impedance frequency is less than original sensor minimum impedance frequency after quality, institute's mass metering exceeds the mass measurement of the sensor
Range.In the case where not changing sensor structure size, as shown in figure 4, by adjusting additional capacitor CpWith the method for resistance R
Increase its mass measurement range.Wherein, additional capacitor CpFor tunable capacitor.
By adjusting additional capacitor CpMethod changes device sensitivity, and the measurement sensitivity is
Wherein, RmFor piezoelectric cantilever sensor dynamic electric resistor, CmFor piezoelectric cantilever sensor dynamic capacity, LmFor pressure
Electric cantilever beam sensor dynamic inductance, ωnFor input voltage frequency, CpFor additional capacitor, Δ m is load mass.
Specific embodiment:
Embodiment one
It is illustrated in figure 5 second-order modal piezoelectric cantilever sensor load mass front and back impedance nearby, phase angle becomes with frequency
Change curve.It is detection frequency with a certain specific frequency near former resonance frequency, impedance becomes at the frequency before and after measurement load mass
Change and then obtain loading the size of micro- quality.This example is detection frequency with piezoelectric cantilever sensor original resonance frequency, is obtained
Impedance differences are 520 Ω before and after loading 500 μ g mass, and sensitivity is 1.04 × 106Ω/g, be frequency measurement sensitivity 6.43 ×
10416.2 times of HZ/g.
Embodiment two
This example makes new additional capacitor C using the size of adjustment additional capacitorp1=0.5CpAfterwards, impedance frequency variation is obtained
Curve is as shown in Figure 6.Resonance frequency is detection frequency before load mass, and near resonance frequency, impedance is with frequency approximation line
Property variation and be gradually reduced, pass through at specific frequency the available micro- quality size of load of impedance variations before and after load mass.It answers
Impedance contrast is 457 Ω before and after obtaining 500 μ g mass of load with the device measurement, and sensitivity is 0.914 × 106Ω/g is frequency difference
14.2 times of method measurement sensitivity.
Embodiment three
This example makes new additional capacitor C using the size of adjustment additional capacitorp2=2CpAfterwards, impedance frequency curve is obtained such as
Shown in Fig. 7.Measurement range increases after piezoelectric cantilever sensor shunt capacitance, in corner frequency fturnTwo sides, impedance is with frequency
Equal approximately linear variation, by taking measurement frequency f=5900HZ as an example, before and after 500 μ g microgram quantities of load impedance contrasts be 1.233 ×
105Ω, sensitivity are 2.5 × 108Ω/g is 3888 times of frequency measurement sensitivity.
Above three instance analysis obtains, by adjusting additional capacitor CpImpedance can be made in each rank resonance frequency two sides with frequency
Rate linear change substantially increases the mass measurement range and measurement sensitivity of sensor.
The present invention describes the feasibility of impedance measurement and provides specific measuring circuit, pass through from point of theory
Sensor measurement model is adjusted under the case where not changing sensor structure size to the method for sensor series and parallel additional circuit
It encloses and measurement sensitivity.
Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention., rather than its limitations；To the greatest extent
Pipe present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that: its according to
So be possible to modify the technical solutions described in the foregoing embodiments, or to some or all of the technical features into
Row equivalent replacement；And these are modified or replaceed, various embodiments of the present invention technology that it does not separate the essence of the corresponding technical solution
The range of scheme.
Claims (2)
1. a kind of portable quality test device that declines, it is characterised in that: it includes micro-mass sensor, signal generating module, inspection
Slowdown monitoring circuit and impedance read module；
The micro-mass sensor is piezoelectric cantilever sensor comprising fixed block is connected to the cantilever beam of fixed block and glues
Be affixed on the piezoelectric patches wide on cantilever beam and with cantilever beam, the piezoelectricity leaf length is less than cantilever beam length, the cantilever beam with
Piezoelectric patches is bonded cantilever beam and piezoelectric patches composite log, and cantilever beam is not cantilever beam extended segment with piezoelectric patches bound fraction；
The signal generating module includes signal generating circuit and power amplifier, the power amplifier output end with it is described micro-
The piezoelectric patches lead-out wire of mass sensor connects, the piezoelectric patches connect with resistance R after with additional capacitor CpIt is in parallel；
The impedance read module is parallel to additional capacitor CpBoth ends；By adjusting additional capacitor CpRealization device range and device
The adjusting of measurement sensitivity.
2. micro- quality test device according to claim 1, it is characterised in that: described by adjusting additional capacitor CpIt realizes
The device measurement sensitivity of adjusting are as follows:
Wherein, RmFor piezoelectric cantilever sensor dynamic electric resistor, CmFor piezoelectric cantilever sensor dynamic capacity, LmIt is outstanding for piezoelectricity
Arm beam sensor dynamic inductance, ωnFor input voltage frequency, CpAdditional capacitor, Δ m load mass.
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| CN111272193B (en) * | 2020-02-17 | 2022-06-14 | 东南大学 | MEMS gyroscope online frequency difference identification method based on noise power spectrum estimation |
| CN111486931A (en) * | 2020-04-15 | 2020-08-04 | 大连理工大学 | Measuring circuit and device of constant-frequency piezoelectric micro-mass sensor |
| CN112325998B (en) * | 2020-11-05 | 2021-08-13 | 吉林大学 | Trace substance sensor and method based on internal resonance |
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| TWI354777B (en) * | 2007-12-28 | 2011-12-21 | Tatung Co | Dual mode measurement system with quartz crystal m |
| CN102954829A (en) * | 2012-11-18 | 2013-03-06 | 大连理工大学 | Micro-particle weighing sensor of V-shaped folding cantilever beam structure |
| CN103424327B (en) * | 2013-07-25 | 2015-06-17 | 大连理工大学 | High-order mode micro-mass sensor based on variable-thickness girder structure and sensitivity improving method thereof |
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| CN101951253A (en) * | 2010-08-27 | 2011-01-19 | 上海西门子医疗器械有限公司 | Joystick |
| CN102158083A (en) * | 2011-04-22 | 2011-08-17 | 复旦大学 | BUCK converter for stabilizing output light flux of LED (light-emitting diode) |
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