CN102967351A - Multipurpose micro-mass sensor of porous cantilever structure - Google Patents

Abstract

A multipurpose micro-mass sensor of a porous cantilever structure belongs to the technical field of multipurpose detection sensors. The micro-mass sensor is characterized in that the upper surface of a porous cantilever which is connected with a fixed block is connected with a piezoelectric film, and the areas of the extension part of the cantilever are a plurality of different detection areas with the same sensitivity. The mass of a detected object is accurately calculated according to the data output of the piezoelectric film. The induction of the porous cantilever can realize the following functions: (a) the plurality of detection areas are effectively isolated; (b) the sensitivities of all the positions in the detection areas are highly consistent with each other, so that the position sensitivity of a test result is reduced; and (c) specific examples show that compared with a conventional planar type sensor structure, the multipurpose micro-mass sensor has the sensitivity which can be increased by 187% at most. The multipurpose micro-mass sensor has the characteristics of simplicity in structure, wide measurement scope, good uniformity, high sensitivity and the like, and thus can be widely applied to gas/liquid concentration measurement and the measurement of cell growth and microorganism, such as bacteria or virus and the like.

Description

A kind of multi-usage micro-mass sensor of porous cantilever beam structure

Technical field

The present invention relates to a kind of multi-usage micro-mass sensor of porous cantilever beam structure, belong to multi-usage acquisition sensor technical field, be mainly used in the high-acruracy survey of multiple different liquids concentration, Growth of Cells and microorganism such as the materials such as bacterium or viral quality.

Background technology

The piezoelectric type micro-mass sensor mainly is attached to structural resonance frequency that the quality of the material of sensor surface causes by measurement to be changed and comes the detection material composition, have simple in structure, response is fast, low and the high characteristics of precision of cost have widely application on microorganism detection such as bacterium and the aspects such as virus, molecule, gas/liquid body composition and concentration.Its ultimate principle can be explained with following formula, Δ f _i=-f _iΔ m/M _e, f wherein _iBe sensor i rank resonance frequency, M _eBe the semi-girder equivalent mass, m is that unit area increases quality, f _iThe sensor resonant frequency variation that causes for increasing quality m.The micro-mass sensor of conventional planar structure is subjected to the restriction on single-measurement plane, is difficult to effectively divide different measured zone, thereby is mainly used in single measurement of planting material, and sensitivity is subjected to the impact of measuring position comparatively serious.International monopoly WO 2005/043126 A2 proposes to adopt the square-section cantilever beam sensor of single piezoelectric patches excitation, because the rigidity mass ratio of square-section semi-girder fixes and search coverage is single plane, directly cause its measurement of species single, limited its application at aspects such as gas/liquid concentration, size-measure of small particles.US Patent No. 6722200 proposes a kind of silicon materials sensor of measuring monatomic quality, the sensitivity of semi-girder marginal position will be starkly lower than the center, because this sensor mainly relies on the mode of absorption to fix tested atom, so that absorption position can directly affect measurement result.US Patent No. 6389877 B1 and domestic patent CN1250156A adopt the cantilever design of single head and double end to come survey frequency, although increase measured zone by increasing the cantilever area, have also increased the effective mass M of system of semi-girder simultaneously _e, be unfavorable for the raising of transducer sensitivity, there is the contradiction between the increase of search coverage area and the sensitivity.Nearest domestic patent of invention publication number CN 1609555A proposes to adopt to measure to adsorb has the method for the oscillator displacement difference of surveying thing to come measurement quality, but wherein needs complicated optical displacement measurement system, increases and measures cost.Document " optical precision engineering " first phase in 2012 " based on the design of the micro-mass sensor of slot type cantilever beam structure " although described in sensor effectively promoted the sensitivity of sensor, sensitivity is subject to the impact of measuring position easily.

Analysis-by-synthesis is found, is subjected to the restriction of self structure, but plane formula mass sensor existence measured zone is little, the measurement kind is single and sensitivity is subject to the weakness that the measuring position affects, and has had a strong impact on its scope of application.Therefore, need in the situation that promotes sensitivity, enlarge the measured zone of sensor, and reduce the measuring position to the influence degree of sensitivity.

Summary of the invention

The present invention is directed to that existing micro-mass sensor measured zone is single, sensitivity low and sensitivity depends critically upon the weakness of detecting location, a kind of multi-usage micro-mass sensor of porous cantilever beam structure is provided, utilize the porous cantilever beam structure effectively to separate different search coverages and lifting sensitivity, make the measuring accuracy of sensor be no longer dependent on the measuring position.Find that with simulation comparison under same scale, the sensitivity of porous cantilever beam structure micro-mass sensor is 2.21～2.87 times of square-section beam sensor by experiment.The micro-mass sensor that proposes has a plurality of concentrated measured zone, unit area is highly sensitive and the characteristics of good stability, has at aspects such as Growth of Cells, liquid component and concentration widely to use.

Technical scheme of the present invention is: a kind of multi-usage micro-mass sensor of porous cantilever beam structure, it comprises semi-girder, piezoelectric membrane and a fixed block, described semi-girder adopts is with reeded porous semi-girder, the upper surface of porous semi-girder is connecting piezoelectric membrane, and one end be connected in fixed block, survey the poor f of resonance frequency of thing front and back by measuring cantilever design in absorption, and then calculate the quality m that surveys thing.

Described porous semi-girder adopts single groove or many grooves porous semi-girder.

Described porous semi-girder arranges the axial hole of some vertically.

Described axial hole is rectangular opening, circular hole or polygonal hole.

The groove corner angle of described porous semi-girder with surface groove are greater than 0 degree with between less than 180 degree.

Described piezoelectric membrane length is less than the porous semi-girder length with surface groove.

The resonance frequency of described semi-girder piezoelectric membrane cover part and extension satisfies f _1i=f _2i, f wherein _1iAnd f _2iBe respectively the resonance frequency of piezoelectricity composite bed and extended layer.

The method for designing of the multi-usage micro-mass sensor of described a kind of porous cantilever beam structure is as follows:

Calculating formula for the resonance frequency of porous cantilever beam structure is:

$f_{1i}=\frac{{\mathrm{\λ}}_{1i}^2}{2\mathrm{\π}{L}_1^2}\sqrt{\frac{\mathrm{\Σ}{E}_i{I}_i}{\mathrm{\Σ}{A}_i{\mathrm{\ρ}}_i}}$

Wherein,

$\mathrm{\&Sigma;}{E}_i{I}_i=E_1\{I_1+[{\left(\frac{H_e}{2}\right)}^2-{(\frac{H_{\mathrm{<figure-callout\; id="2"\; label="e"\; filenames="HDA00002422442800011.png,HDA00002422442800013.png"\; state="\{\{state\}\}">e</figure-callout>}}}{2}+t_n)}^2\left]\right[w_{1}h+w_{3}h+2h(H+h)+(w_2-2h)h\left]\right\}+E_p[\frac{{\mathrm{<figure-callout\; id="3"\; label="bt\; p"\; filenames="HDA00002422442800011.png"\; state="\{\{state\}\}">bt</figure-callout>}}_p^{}}{12}+{(\frac{t_p}{2}-t_n)}^2{\mathrm{bt}}_p]$

$\begin{array}{c}{I}_1=\frac{w_1+{\mathrm{<figure-callout\; id="3"\; label="w"\; filenames="HDA00002422442800011.png"\; state="\{\{state\}\}">w</figure-callout>}}_3}{3}\&CenterDot;{\mathrm{<figure-callout\; id="3"\; label="h"\; filenames="HDA00002422442800011.png"\; state="\{\{state\}\}">h</figure-callout>}}^3+\frac{w_2-2h}{12}\&CenterDot;{\mathrm{<figure-callout\; id="3"\; label="h"\; filenames="HDA00002422442800011.png"\; state="\{\{state\}\}">h</figure-callout>}}^3+{(\frac{\mathrm{<figure-callout\; id="2"\; label="h"\; filenames="HDA00002422442800011.png,HDA00002422442800013.png"\; state="\{\{state\}\}">h</figure-callout>}}{2}+H)}^2\&CenterDot;(w_2-2h)\&CenterDot;h+\frac{2h}{3}{(H+h)}^3-\\ n_1[\frac{x_2{\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="HDA00002422442800011.png,HDA00002422442800013.png"\; state="\{\{state\}\}">y</figure-callout>}}_2^3}{12}+{(\frac{h}{2}-\frac{x_2}{2})}^2{x}_2{y}_2]-n_2\frac{n_2{\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="HDA00002422442800011.png,HDA00002422442800013.png"\; state="\{\{state\}\}">y</figure-callout>}}_2^3}{12}-\underset{i=1}{\overset{\frac{{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="HDA00002422442800011.png,HDA00002422442800013.png"\; state="\{\{state\}\}">n</figure-callout>}}_2}{2}}{\mathrm{\&Sigma;}}}{({\mathrm{ix}}_i+\frac{2i-1}{2}{h}_i)}^2{b}_i{h}_i\end{array}$

$x_i=\frac{H-\frac{{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="HDA00002422442800011.png,HDA00002422442800013.png"\; state="\{\{state\}\}">n</figure-callout>}}_2}{2}{y}_2}{\frac{{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="HDA00002422442800011.png,HDA00002422442800013.png"\; state="\{\{state\}\}">n</figure-callout>}}_2}{2}+1}$ ， $b_i={\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="HDA00002422442800011.png,HDA00002422442800013.png"\; state="\{\{state\}\}">y</figure-callout>}}_2$ ， $h_i=x_2$ ， $H_e=\sqrt[3]{\frac{3I_1}{w_1+{\mathrm{<figure-callout\; id="2"\; label="w"\; filenames="HDA00002422442800011.png,HDA00002422442800013.png"\; state="\{\{state\}\}">w</figure-callout>}}_2+{\mathrm{<figure-callout\; id="3"\; label="w"\; filenames="HDA00002422442800011.png"\; state="\{\{state\}\}">w</figure-callout>}}_3}}$ ， $w_1={\mathrm{<figure-callout\; id="3"\; label="w"\; filenames="HDA00002422442800011.png"\; state="\{\{state\}\}">w</figure-callout>}}_3$ ， $t_n=\frac{\frac{1}{2}{E}_p{t}_p^2-\frac{1}{2}{E}_1{H}_e^2}{E_1{H}_e+E_p{t}_p}$

$\mathrm{\&Sigma;}{A}_i{\mathrm{\&rho;}}_i={\mathrm{\&rho;}}_1[w_{1}h+w_{3}h+2h(H+h)+h(w_2-2h)]+{\mathrm{\&rho;}}_p{\mathrm{bt}}_p$

Wherein, λ _1iThe coefficient relevant with each rank mode eigenvalue, E _p, E ₁Be respectively the elastic modulus of piezoelectric and semi-girder material, t _p, h, b, w ₂, H, w ₁, w ₃, be respectively piezoelectric film thickness, semi-girder thickness, semi-girder width, recess width, groove height, multi-hole beam arranged on left and right sides wing width, x ₂, y ₂, n ₁, n ₂Be respectively the rectangular opening width, highly, flat number of perforations, vertical core number, t _n, H _eBe respectively neutral line position, equivalent mass and semi-girder equivalent thickness, A _i, ρ _iBe the corresponding area of section of each layer and density of material.

Resonance frequency f for the semi-girder extension _2i, computing formula is:

$f_{2i}=\frac{{\mathrm{\&lambda;}}_{2i}^2}{2\mathrm{\&pi;}{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="HDA00002422442800011.png,HDA00002422442800013.png"\; state="\{\{state\}\}">L</figure-callout>}}_2^2}\sqrt{\frac{\mathrm{\&Sigma;}{E}_i{I}_i}{\mathrm{\&Sigma;}{A}_i{\mathrm{\&rho;}}_i}}$

Wherein,

$\mathrm{\&Sigma;}{E}_i{I}_i=E_1\{I_1+[{\left(\frac{H_e}{2}\right)}^2-{(\frac{H_{\mathrm{<figure-callout\; id="2"\; label="e"\; filenames="HDA00002422442800011.png,HDA00002422442800013.png"\; state="\{\{state\}\}">e</figure-callout>}}}{2}+t_n)}^2\left]\right[w_{1}h+w_{3}h+2h(H+h)+(w_2-2h)h\left]\right\}$

$\mathrm{\&Sigma;}{A}_i{\mathrm{\&rho;}}_i={\mathrm{\&rho;}}_1[w_{1}h+w_{3}h+2h(H+h)+h(w_2-2h)]$

The ratio of described a kind of porous cantilever beam structure and rectangular cross section beam resonance frequency satisfies following formula

$\mathrm{\&gamma;}=\sqrt{12\left\{\begin{array}{c}\frac{w_1+{\mathrm{<figure-callout\; id="3"\; label="w"\; filenames="HDA00002422442800011.png"\; state="\{\{state\}\}">w</figure-callout>}}_3}{3}\&CenterDot;h+\frac{w_2-2h}{12}\&CenterDot;h+{(\frac{\mathrm{<figure-callout\; id="2"\; label="h"\; filenames="HDA00002422442800011.png,HDA00002422442800013.png"\; state="\{\{state\}\}">h</figure-callout>}}{2}+H)}^2\&CenterDot;(\frac{w_2}{h}-2)+\frac{2}{3h}{(H+h)}^3-\\ \frac{n_1}{h^2}[\frac{x_2{\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="HDA00002422442800011.png,HDA00002422442800013.png"\; state="\{\{state\}\}">y</figure-callout>}}_2^3}{12}+{(\frac{h}{2}-\frac{x_2}{2})}^2{x}_2{y}_2]-n_2\frac{n_2{\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="HDA00002422442800011.png,HDA00002422442800013.png"\; state="\{\{state\}\}">y</figure-callout>}}_2^3}{12h^2}-\frac{1}{{\mathrm{<figure-callout\; id="2"\; label="h"\; filenames="HDA00002422442800011.png,HDA00002422442800013.png"\; state="\{\{state\}\}">h</figure-callout>}}^2}\underset{i=1}{\overset{\frac{{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="HDA00002422442800011.png,HDA00002422442800013.png"\; state="\{\{state\}\}">n</figure-callout>}}_2}{2}}{\mathrm{\&Sigma;}}}{({\mathrm{ix}}_i+\frac{2i-1}{2}{h}_i)}^2{b}_i{h}_i+\frac{1}{h^2}[{\left(\frac{H_e}{2}\right)}^2-{(\frac{H_{\mathrm{<figure-callout\; id="2"\; label="e"\; filenames="HDA00002422442800011.png,HDA00002422442800013.png"\; state="\{\{state\}\}">e</figure-callout>}}}{2}+t_n)}^2]\end{array}\right\}}$

By adjusting the height H of groove, and the number (n of through hole vertically ₁And n ₂) and the single hole yardstick can effectively promote sensitivity with the porous cantilever beam structure sensor of surface groove, can reach 2.87 times.

The present invention compared with prior art has following advantage:

[1] the present invention adopts the porous cantilever beam structure to substitute traditional square-section girder construction as the key elastic element of mass sensor, has increased sensor resonant frequency, has further promoted the mass area ratio sensitivity of sensor;

[2] the present invention adopts the porous cantilever beam structure to substitute traditional square-section girder construction, can effectively separate different test zones, and the sensitivity of regional is consistent, and detects when having realized many kinds of substance;

[3] porous semi-girder of the present invention makes the sensitivity of sensor be no longer dependent on the measuring position along the mode of axis direction perforate, and when namely the broad ways lumped mass loaded, transducer sensitivity remained unchanged.

The invention has the beneficial effects as follows: described porous cantilever beam structure micro-mass sensor with surface groove has the advantages that simple in structure, highly sensitive, multizone is measured, sensitivity does not rely on the measuring position, weighs on molecule, gas/liquid body composition and concentration, Growth of Cells, microorganism detection such as bacterium and virus, little quality, the field such as danger product detection has widely application value.

Description of drawings

Fig. 1 is a kind of multi-usage micro-mass sensor of porous cantilever beam structure.

Fig. 2 is a kind of example sensitivity of multi-usage micro-mass sensor of porous cantilever beam structure and the traditional rectangular comparison diagram that cuts section bar.

Fig. 3 is embodiment 2 structural representations.

Fig. 4 is the sensitivity of sensor in the embodiment 2 and the traditional rectangular comparison diagram that cuts section bar.

Among the figure: 1, fixed block, 2, piezoelectric membrane, 3, single groove porous semi-girder, 3-1, measured zone one, 3-2, measured zone two, 3-3, measured zone three, 4, dual-cavity porous semi-girder, 4-1, measured zone four, 4-2, measured zone five, 4-3, measured zone six, 4-4, measured zone seven, 4-5, measured zone eight.

Embodiment

Embodiment one

Fig. 1 has provided a kind of multi-usage micro-mass sensor structural representation of porous cantilever beam structure.Wherein, the lower surface of piezoelectric membrane 2 is connected in the upper surface of porous semi-girder 3, and one section of piezoelectric membrane 2 and porous semi-girder is connected in fixed block 1, and the other end is unsettled, forms composite cantilever structure.The seamless connection between piezoelectric membrane 2 and the porous semi-girder, and the length of piezoelectric membrane 2 is less than the porous cantilever beam structure.Take the free end of piezoelectric membrane 2 as boundary, composite cantilever structure is divided into two parts: i.e. composite bed and extended layer.Flange surfaces, the square groove inside surface of extended layer part all can be used as the quality that search coverage detects measured object.Porous semi-girder 3 is highly elastic material.

Under identical geometric parameter (as shown in table 1), getting the listed parameter of table 1 is the structural parameters of the example of embodiment of the present invention one.The Sensitivity comparison curve of the sensitivity that this example obtains and square-section girder construction as shown in Figure 2.According to the definition of transducer sensitivity, the slope of figure cathetus is the sensitivity of respective sensor.When porous semi-girder length was 20.0mm, highly sensitive 1.2 times of the remolding sensitivity rectangle plane formula sensor of this example 1 effectively raised the sensitivity of sensor.

Table 1 example 1 sensor geometric parameter

Sensitivity depends on the problem of measuring position for traditional i shaped cross section mass sensor, and the parameter of choosing example 2 is as shown in table 2.Table 3 has been listed the measurement result correlation data of example 2 with traditional i shaped cross section mass sensor of embodiment one.The position sensing degree maximum that this example obtains only is 0.66%, and the position sensing of the plane i shaped cross section mass sensor of identical parameters is 27.8%.Can find out that from data the example of embodiment one has effectively solved the position dependence problem of sensitivity, for the high-acruracy survey of sensor provides assurance.

The structural parameters of table 2 example 2 sensors

Table 3 transducer sensitivity and position relationship

Embodiment two

Fig. 3 is embodiment two structural representations of the multi-usage micro-mass sensor of a kind of porous cantilever beam structure of the present invention.On the basis of embodiment one, porous semi-girder 3 is replaced with dual-cavity porous semi-girder 4, but the number that further expands its measured zone is 5, is respectively regional 4-1,4-2,4-3,4-4,4-5.

Fig. 4 is the example of embodiment of the present invention two, the Sensitivity comparison of the sensitivity of (as shown in table 1) and square-section girder construction under identical geometric parameter.According to the definition of transducer sensitivity, the slope of figure cathetus is the sensitivity of respective sensor.When porous semi-girder length was 20.0mm, highly sensitive 1.87 times of the remolding sensitivity rectangle plane formula sensor of embodiment two examples effectively raised the sensitivity of sensor.

Claims (6)

1. the multi-usage micro-mass sensor of a porous cantilever beam structure, it comprises a semi-girder, piezoelectric membrane (2) and fixed block (1), it is characterized in that: described semi-girder adopts the porous semi-girder, the upper surface of porous semi-girder is connecting piezoelectric membrane (2), and one end be connected in fixed block (1), survey the poor f of resonance frequency of thing front and back by measuring cantilever design in absorption, and then calculate the quality m that surveys thing.

2. the multi-usage micro-mass sensor of a kind of porous cantilever beam structure according to claim 1, it is characterized in that: described porous semi-girder adopts single surperficial square groove porous semi-girder (3) or a plurality of surperficial square groove porous semi-girders (4).

3. the multi-usage micro-mass sensor of a kind of porous cantilever beam structure according to claim 1 and 2 is characterized in that: the axial hole that some evenly is set vertically of described porous semi-girder.

4. the multi-usage micro-mass sensor of a kind of porous cantilever beam structure according to claim 3, it is characterized in that: described axial hole is rectangular opening, circular hole or polygonal hole.

5. the multi-usage micro-mass sensor of a kind of porous cantilever beam structure according to claim 1 is characterized in that: the groove corner angle of described porous semi-girder are greater than 0 degree with between less than 180 degree.

6. the multi-usage micro-mass sensor of a kind of porous cantilever beam structure according to claim 1, it is characterized in that: described piezoelectric membrane (2) length is less than the length of porous semi-girder.

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