CN104181084A - Aerosol sensor - Google Patents

Abstract

The invention provides an aerosol sensor, comprising: an aerosol inlet, an aerosol charging unit, a deposition unit, a charge detection unit, a control unit, a signal processing unit, and an aerosol outlet; the aerosol inlet, the aerosol charging unit unit, the deposition unit, the charge detection unit, and the aerosol outlet are sequentially connected, the charge detection unit is connected to the signal processing unit, and the control unit is connected to the deposition unit and the charge detection unit respectively connected; the charge detection unit includes at least one charge detection subunit, the charge detection subunits are connected in turn, each of the charge detection subunits is connected to the control unit, and each of the charge detection subunits is connected to the control unit respectively. The signal processing unit is connected. Through the aerosol sensor provided by the invention, the measurement of aerosol particles in a wide particle diameter measurement range can be realized, and at the same time, miniaturization is easy.

Description

An aerosol sensor

technical field

The invention relates to the technical field of aerosol measurement, in particular to an aerosol sensor.

Background technique

Aerosol is a suspension system formed by suspending liquid or solid particles in a gas medium, in which the characteristic particle size of the particle phase is generally 1nm to 100μm, but because particles with a particle size larger than 1μm are easy to settle, the stable suspension time is short. Particles with a particle size of less than 10nm are difficult to detect, so general aerosol real-time measurement is only for aerosol particles in the range of 10nm to 1μm.

Concentration and particle size are the two most important indicators of aerosols. The existing aerosol real-time measurement methods for these two indicators mainly include methods based on optical principles and methods based on electrical principles. Traditional instruments based on optical principles mainly include optical particle counters and laser particle counters. Since the light scattering of particles smaller than the wavelength of light is very weak, pure optical methods are generally only effective for particles larger than 0.3 μm in size. Measuring instruments based on electrical principles mainly include differential electric mobility analyzers, scanning electric mobility spectrometers (combined with condensation nuclei particle counters), etc., which use the principle that the electric mobility of charged particles in an electric field is inversely proportional to the particle size, and Aerosol electrical detectors, etc., which have a definite exponential relationship between the charge amount and particle size of particles in a certain size range, are used.

In the existing technology, the instruments capable of real-time measurement of aerosols in a wide range are almost all large-scale instruments with complex structures, which cannot meet the requirements of multi-point and distributed applications in a limited space environment. However, some miniaturized aerosol measuring instruments have a smaller measurement range.

Contents of the invention

The invention provides an aerosol sensor, which can realize the measurement of aerosol particles in a wide particle diameter measurement range and is easy to miniaturize at the same time.

The invention provides an aerosol sensor, comprising:

Aerosol inlet, aerosol charging unit, deposition unit, charge detection unit, control unit, signal processing unit, aerosol outlet;

The aerosol inlet, the aerosol charging unit, the deposition unit, the charge detection unit, and the aerosol outlet are sequentially connected, the charge detection unit is connected to the signal processing unit, and the control unit is respectively connected to the deposition unit and the charge detection unit;

The charge detection unit includes at least one charge detection subunit, the charge detection subunits are connected in sequence, each of the charge detection subunits is connected to the control unit, each of the charge detection subunits is respectively connected to the The signal processing unit is connected;

The aerosol charging unit is used to charge the aerosol particles in the inflowing aerosol to be measured;

The deposition unit is used to intercept the aerosol particles whose particle size is smaller than or equal to the initial preset value among the charged aerosol particles flowing in;

The charge detection subunit is used to intercept the aerosol particles whose particle size is smaller than or equal to the preset value of the charge detection subunit in the charged aerosol particles flowing in, and output the generated induced current;

The control unit is configured to apply a square wave voltage to the deposition unit according to the initial preset value, and apply the preset voltage to each of the charge detection subunits according to the preset value of each charge detection subunit. The constant voltage corresponding to the set value;

The signal processing unit is used to calculate the average particle size and number concentration of the trapped aerosol particles in each charge detection subunit according to the induced currents and analytical expressions output by all the charge detection subunits, wherein, The analytical expression is a multivariate polynomial between the induced current, the average particle size, and the number concentration that meet the preset accuracy requirements;

Or, the signal processing unit is used to calculate the average particle size and number concentration of the trapped aerosol particles in each charge detection subunit according to the induced current output by all the charge detection subunits and the neural network model, wherein , the neural network model is used to obtain the average particle size and the number concentration according to the input induced current;

Wherein, the low level of the square wave voltage satisfies: among the charged aerosol particles flowing into the deposition unit, aerosol particles with a particle size smaller than or equal to the initial preset value are all trapped in the deposition unit;

The high level of the square wave voltage satisfies: among the charged aerosol particles flowing into the deposition unit, all the aerosol particles whose particle size is smaller than or equal to the initial preset value are all trapped in the deposition unit, and Part of the aerosol particles whose particle size is larger than the initial preset value is also trapped in the deposition unit;

The constant voltage corresponding to the preset value of the charge detection subunit satisfies: among the charged aerosol particles flowing into each of the charge detection subunits, all the aerosol particles whose particle diameter is smaller than or equal to the preset value of the charge detection subunit Trapped in said charge detection subunit;

Wherein, at least one of all the preset values is greater than the initial preset value.

Further, a filter membrane is installed in the aerosol inlet, and the filter membrane is used to filter out aerosol particles whose particle size is greater than or equal to a preset particle size threshold, and the preset particle size threshold is equal to a maximum preset value.

Further, the aerosol electrified unit is a pin-plate ion source, the positive pole of the pin-plate ion source is a conductive tip, and the negative pole is a flat plate electrode.

Further, the conductive tip includes: a conductive one-dimensional nanostructure, an insulating one-dimensional nanostructure covered with a metal layer, and a semiconductor one-dimensional nanostructure covered with a metal layer.

Further, the one-dimensional nanostructures include: nanowires, nanotubes, and nanorods.

Further, the aerosol electrified unit is a wire-barrel ion source, the anode of the wire-barrel ion source is a conductive filament, and the anode is a cylindrical electrode.

Further, the deposition unit includes two parallel electrode plates, one of which is grounded, and the other electrode plate is connected to the control unit.

Further, each of the charge detection subunits includes two parallel electrode plates and an ammeter, wherein one electrode plate is connected to the control unit, the other electrode plate is connected to the ammeter, and the ammeter is connected to the signal processing unit connected, the ammeter is used to measure the induced current and output the magnitude of the measured induced current.

Further, the charge detection subunit connected to the aerosol outlet is a Faraday cage or a Faraday disk.

Further, the aerosol sensor further includes: a drive unit, used to drive the aerosol to be measured to flow in the aerosol sensor, the drive unit is connected to the aerosol inlet, or the drive unit is connected to the aerosol The sol outlet is connected.

An aerosol sensor provided by the present invention can achieve a wider particle size through the combination measurement of multiple charge detection subunits, and perform data fusion processing on the induced current of each charge detection subunit through an analytical expression or a neural network model. Particle size distribution measurement of aerosol particles in the measurement range while being easy to miniaturize.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are For some embodiments of the present invention, those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 is a schematic structural diagram of an aerosol sensor provided by an embodiment of the present invention;

Fig. 2 is a schematic structural diagram of another aerosol sensor provided by an embodiment of the present invention;

Fig. 3 is a structural diagram of a neural network model provided by an embodiment of the present invention.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments It is a part of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work belong to the protection of the present invention. scope.

The present invention provides an aerosol sensor, referring to Fig. 1, comprising:

Aerosol inlet 101 , aerosol charging unit 102 , deposition unit 103 , charge detection unit 104 , control unit 105 , signal processing unit 106 , and aerosol outlet 107 .

The aerosol inlet 101, the aerosol charging unit 102, the deposition unit 103, the charge detection unit 104, and the aerosol outlet 107 are sequentially connected, and the charge detection unit 104 is connected to the signal processing unit 106 The control unit 105 is connected to the deposition unit 103 and the charge detection unit 104 .

The charge detection unit 104 includes at least one charge detection subunit, the charge detection subunits are connected in sequence, each of the charge detection subunits is respectively connected to the control unit, and each charge detection subunit is respectively connected to the signal The processing units are connected; the charge detection subunit 1041 to the charge detection subunit 104n shown in the figure.

Wherein, the aerosol to be measured enters from the aerosol inlet 101, flows through the aerosol charging unit 102, the deposition unit 103, and the charge detection unit 104 in sequence, and flows out from the aerosol outlet 107. In the detection unit, the aerosol to be measured flows through each charge detection subunit sequentially, that is, after the aerosol to be measured flows out from the deposition unit, it flows through the charge detection subunit 1041 to the charge detection subunit 104n in sequence, and from the charge detection subunit 104n After flowing out, it flows into the aerosol outlet 107 .

The aerosol charging unit 102 is used to charge the aerosol particles in the incoming aerosol to be tested.

Specifically, after the aerosol particles flow through the aerosol charging unit 102, they are all charged by means of diffusion charging or field charging. The charged amount of aerosol particles is related to the particle size of the aerosol particles.

The deposition unit 103 is used to intercept aerosol particles whose particle diameter is smaller than or equal to an initial preset value among the charged aerosol particles flowing in.

The charge detection sub-units 1041-104n are used to intercept the aerosol particles whose particle diameter is smaller than or equal to the preset value of the charge detection sub-unit in the charged aerosol particles flowing in, and output the generated induced current.

Specifically, each charge detection subunit corresponds to a preset value, for example: the charge detection subunit 1041 corresponds to the first preset value, the charge detection subunit 104n corresponds to the nth preset value, and the preset value corresponding to each charge detection subunit The set value is determined according to the requirements for the measurement range of aerosol particles. When the aerosol flows through the current charge detection subunit, the aerosol particles whose particle size is smaller than or equal to the preset value corresponding to the charge detection subunit will be trapped in the charge detection subunit.

The control unit 105 is configured to apply a square wave voltage to the deposition unit 103 according to the initial preset value, and respectively apply and The preset value corresponds to a constant voltage. Among them, after the charged aerosol particles enter the deposition unit, when the voltage applied to the deposition unit is at a low level, the aerosol particles with a particle size smaller than or equal to the initial preset value are trapped in the deposition unit, and when the voltage applied to the deposition unit When the level is high, in addition to the aerosol particles whose particle size is smaller than or equal to the initial preset value are trapped in the deposition unit, some aerosol particles with a particle size larger than the initial preset value are also trapped in the deposition unit.

Specifically, the interception of aerosol particles by the deposition unit 103 and each charge detection subunit 1041-104n needs to be realized by controlling the voltage applied by the unit. The control unit adjusts the voltage applied to the deposition unit and each charge detection subunit to meet the particle size requirements of the aerosol particles trapped in the deposition unit and each charge detection subunit. For different initial preset values of the deposition unit, the control unit should apply a corresponding voltage, and the corresponding relationship between the initial preset value and the voltage can be obtained through experiments. For different preset values of each charge detection subunit, the control unit needs to apply different voltages, and the corresponding relationship between the preset values and voltages can be obtained through experiments.

The signal processing unit 106 is configured to calculate the average particle size and number concentration of the trapped aerosol particles in each charge detection subunit according to the induced currents and analytical expressions output by all the charge detection subunits, wherein, The analytical expression is a multivariate polynomial between the induced current, the average particle size, and the number concentration that meet the preset accuracy requirements;

Or, the signal processing unit 106 is configured to calculate the average particle size and number concentration of the trapped aerosol particles in each charge detection subunit according to the induced current output by all the charge detection subunits and the neural network model, Wherein, the neural network model is used to obtain the average particle size and the number concentration according to the input induced current.

Wherein, the low level of the square wave voltage satisfies that among the charged aerosol particles flowing into the deposition unit 103 , the aerosol particles whose particle diameter is smaller than or equal to the initial preset value are all trapped in the deposition unit. The high level of the square wave voltage satisfies: among the charged aerosol particles flowing into the deposition unit 103, all the aerosol particles whose particle diameter is smaller than or equal to the initial preset value are all trapped in the deposition unit, and Part of the aerosol particles whose particle diameter is larger than the initial preset value are also trapped in the deposition unit. Preferably, the low level of the square wave voltage satisfies: among the charged aerosol particles flowing into the deposition unit 103, only the aerosol particles whose particle size is smaller than or equal to the initial preset value are all trapped in the deposition unit Inside.

The constant voltage corresponding to the preset value of the charge detection subunit satisfies: among the charged aerosol particles flowing into each of the charge detection subunits, all the aerosol particles whose particle diameter is smaller than or equal to the preset value of the charge detection subunit Trapped in said charge detection subunit;

Wherein, at least one of all the preset values is greater than the initial preset value.

The aerosol sensor provided in this embodiment can achieve a wide particle size measurement range by combining measurement with more than two charge detection subunits, and performing data fusion processing on the induced current through an analytical expression or a neural network model. Measurement of aerosol particles while being easy to miniaturize. In addition, in this embodiment, a plurality of charge detection subunits can make the measurement result more precise and accurate.

When there are aerosol particles with a particle size greater than or equal to the maximum preset value in the aerosol that is passed in, some aerosol particles cannot be trapped in the aerosol sensor, which will cause inaccurate measurement of the aerosol. In order to make the aerosol The measurement of the sol sensor is more accurate, and the aerosol needs to be filtered. A filter membrane is installed in the aerosol inlet, and the filter membrane is used to filter out aerosol particles whose particle size is greater than or equal to a preset particle size threshold, and the preset particle size threshold is equal to a maximum preset value.

In a possible implementation manner, the aerosol electrification unit is a pin-plate ion source, the positive pole of the pin-plate ion source is a conductive tip, and the negative pole is a flat plate electrode. Wherein, the conductive tip includes: a conductive one-dimensional nanostructure, an insulating one-dimensional nanostructure whose surface is covered with a metal layer, and a semiconductor one-dimensional nanostructure whose surface is covered with a metal layer. The one-dimensional nanostructures include: nanowires, nanotubes, and nanorods. The metal layer is high temperature resistant and has a low work function.

The conductive tip may also be a nanoscale tip entirely micromachined. The tip of the positive electrode is connected to a high level, and the plate electrode is connected to a low level or grounded. In addition, the aerosol tape charge unit can use needle-point corona discharge as the ion source, and the needle-point electrode can use tungsten needles or nanowires, nanotubes, and nanorods.

Alternatively, the aerosol electrified unit is a wire-barrel ion source, the anode of the wire-barrel ion source is a conductive filament, and the anode is a cylindrical electrode.

In a possible implementation manner, the deposition unit includes two parallel electrode plates, one electrode plate is grounded, and the other electrode plate is connected to the control unit.

In a possible implementation manner, each of the charge detection subunits includes two parallel electrode plates and an ammeter, wherein one electrode plate is connected to the control unit, and the other electrode plate is connected to the ammeter, and the ammeter Connected with the signal processing unit, the ammeter is used to measure the induced current and output the magnitude of the measured induced current. Wherein, the charge detection subunit connected to the aerosol outlet may be a Faraday cage or a Faraday disk.

In a possible implementation manner, the charge detection unit is composed of a first charge detection subunit and a second charge detection subunit; the first charge detection subunit is connected to the deposition unit, and the second charge detection subunit The detection subunit is connected to the first charge detection subunit.

Wherein, the signal processing unit is used to calculate the average particle size and number concentration of the trapped aerosol particles in each charge detection subunit according to the induced currents and analytical expressions output by all the charge detection subunits, wherein , the analytical expression is a multivariate polynomial between the induced current, the average particle size, and the number concentration that meet the preset precision requirements.

Among them, the analytical expression can be obtained by the following method:

S11: Collect the induced current obtained by measuring the calibration aerosol with the aerosol sensor, wherein the average particle size and number concentration of the calibration aerosol are known;

S12: Set the multivariate polynomials of induced current, average particle size, and number concentration.

S13: Fitting the multivariate polynomial by least square method to obtain parameters of the multivariate polynomial;

S14: Compare the average particle size and number concentration output by the multivariate polynomial with the average particle size and number concentration of the aerosol particles in the calibration aerosol, if the average particle size and number concentration output by the multivariate polynomial are the same as the If the error between the average particle size and number concentration of the aerosol particles in the calibration aerosol is less than or equal to the first preset threshold, then the fitting ends; otherwise, correct the degree of the multivariate polynomial and return to S13.

The signal processing unit can also be used to calculate the average particle size and number concentration of the trapped aerosol particles in each charge detection subunit according to the induced current output by all the charge detection subunits and the neural network model, wherein , the neural network model is used to obtain the average particle size and the number concentration according to the input induced current. Wherein, the neural network model may be a BP neural network model.

Wherein, the modeling method of described neural network model is as follows:

S21: Collect the induced current obtained by measuring the calibration aerosol with the aerosol sensor, wherein the average particle size and number concentration of the calibration aerosol are known;

S22: Setting a neural network model, and calibrating the neural network model;

S23: Input each output induction current of the aerosol sensor into the calibrated neural network model to obtain the average particle size and number concentration output by the neural network model.

Wherein, the neural network model is calibrated in step S22, specifically including:

S221: Setting a neural network model, initializing the neural network model, including setting initial values of weight parameters W ₁ and W ₂ of the neural network model;

S222: Collect the induced current obtained by measuring the calibration aerosol with the aerosol sensor;

S223: Use a neural network learning algorithm to learn weight parameters in the neural network model, input the induced current into the learned neural network model, and obtain an output average particle size and number concentration of the neural network model;

S224: Compare the average particle size and number concentration output by the neural network model with the average particle size and number concentration of the aerosol particles of the calibration aerosol, if the average particle size and number concentration output by the neural network model If the error between the average particle size and the number concentration of the aerosol particles of the calibration aerosol is less than or equal to the second preset threshold, then the calibration ends, otherwise, return to S223.

The above two signal processing units use the data fusion method to obtain the particle size distribution and number concentration of the aerosol particles to be measured according to the inversion of the induced current measured on each charge detection sub-unit, which breaks through the particle charge amount in Fuch's diffusion charging theory The simple approximate linear relationship with particle size is only effective in the range of 10-300nm, expanding the measurement range of aerosol sensors based purely on electrical principles.

In addition, the aerosol sensor also includes: a drive unit, used to drive the aerosol to be measured to flow in the aerosol sensor, the drive unit is connected to the aerosol inlet, or the drive unit is connected to the aerosol The outlet is connected. Wherein, the driving unit may be a micropump; the driving unit may also be a fan or a compressor.

The aerosol sensor further includes: an output unit configured to output the average particle diameter and the number concentration.

Fig. 2 shows a kind of aerosol sensor, and this aerosol sensor comprises:

An aerosol inlet 6 and an aerosol outlet 7 located on the aerosol sensor housing 5, a filter membrane 10 is installed in the aerosol inlet 6; aerosol inlet 6, aerosol electrification unit 1, deposition unit 2, first charge detection subunit 3 , the second charge detection subunit 4, and the aerosol outlet 7 are sequentially connected;

Among them, the aerosol tape charging unit 1 is a pin-plate positive corona discharge ion source. After the aerosol particles flow through the ion source, they are all positively charged by diffusion charging or field charging. The positive tip of the ion source is assisted by an electric field. The ZnO nanowire 16 prepared by the wet chemical method, the nanowire 16 can be directly grown on the electrode plate 17, or can be transferred to the electrode plate 17 by the pre-grown nanowire, and the surface of the nanowire is covered with high temperature resistant and functional Metal layers with lower function, such as tungsten metal layers. During the measurement, the nanowire 16 as the tip of the positive electrode is connected to the high voltage V ₀ through the electrode plate 17 , and the opposite planar electrode 12 is connected to the low voltage or grounded. The electrode plate 17 and the electrode plate 12 are installed on the aerosol sensor housing 5 via the insulator 18 and the insulator 14 respectively.

The deposition unit 2 includes: an electrode plate 21 and an electrode plate 22, the electrode plate 21 and the electrode plate 22 are parallel to each other, and are installed on the aerosol sensor housing 5 through an insulator 23 and an insulator 24 respectively, and the electrode plate 21 is connected to the control unit 8 .

The first charge detection subunit 3 includes: an electrode plate 31, an electrode plate 32, and an ammeter 35. The electrode plate 31 and the electrode plate 32 are parallel to each other, and are respectively installed on the aerosol sensor housing 5 via an insulator 33 and an insulator 34. The electrode plate 31 is connected to the control unit 8 , the electrode plate 32 is connected to the ammeter 35 , and the ammeter 35 is connected to the signal processing unit 9 .

The second charge detection subunit 4 includes: an electrode plate 41, an electrode plate 42, and an ammeter 45. The electrode plate 41 and the electrode plate 42 are parallel to each other, and are respectively installed on the aerosol sensor housing 5 via an insulator 43 and an insulator 44. The electrode plate 41 is connected to the control unit 8 , the electrode plate 42 is connected to the ammeter 45 , and the ammeter 45 is connected to the signal processing unit 9 .

It should be noted that: the filter membrane 10 is used to filter out aerosol particles whose particle size is greater than or equal to the second preset value _d3 .

After the aerosol enters from the aerosol inlet 6, it flows through the aerosol electrification unit 1, and the aerosol particles are charged after passing through the aerosol electrification unit 1; the control unit 8 applies a low level of V ₁ and a high level of The square wave voltage of _V2 , the electrode plate 22 is grounded. The low level V ₁ and the high level V ₂ of the square wave voltage generate electric fields with strengths E ₁ and E ₂ respectively between the electrode plate 21 and the electrode plate 22, and the positively charged aerosol particles entering the deposition unit 2 are Under the action of the electric fields E ₁ and E ₂ , it will deflect toward the electrode plate 22 . Since charged aerosol particles with a smaller particle size have a larger electrical mobility, the control unit 8 applies a low level V ₁ corresponding to the initial preset value d ₁ so that all charged aerosol particles with a particle size smaller than or equal to d ₁ at this time The electrosol particles are all deposited on the electrode plate 22 . However, the charged aerosol particles with a particle size larger than _d1 are not deposited at the low level _V1 due to their relatively small electric mobility, but all enter the first charge detection subunit 3, and at the same time, the high level V2 makes the charge detection subunit ₃ At this time, some of the charged aerosol particles with a particle size greater than d ₁ are deposited on the electrode plate 22 , and the rest of the charged aerosol particles with a particle size greater than d ₁ enter the first charge detection subunit 3 . In this way, due to the change of the high and low levels of the wave voltage applied to the deposition unit 2, the charged aerosol particles flowing through the deposition unit 2 realize the conversion of two different concentrations.

The control unit 8 applies a constant voltage V ₃ on the electrode plate 31, and the constant voltage V ₃ causes an electric field with an intensity of E ₃ to be generated between the electrode plate 31 and the electrode plate 32, and the positive charge entering the first charge detection subunit 3 The aerosol particles will be deflected towards the electrode plate 32 under the action of the electric field E ₃ , and an induced current will be induced in the ammeter 35 at the same time. The control unit 8 applies _V3 corresponding to the first preset value _d2 so that the charged aerosol particles with a particle size smaller than or equal to _d2 are all deposited on the electrode plate 32, while the charged aerosol particles with a particle size larger than _d2 are deposited on the deposition unit When the voltage on the deposition unit 2 is at a low level, all of them enter the second charge detection subunit 4, and when the voltage on the deposition unit 2 is at a high level, the charged aerosol particles with a particle diameter greater than _d2 are partially deposited on the electrode plates 22 and 32, and some Enter the second charge detection subunit 4. At the same time, due to the action of the wave voltage on the deposition unit 2, the particle diameter of the charged aerosol particles flowing into the first charge detection subunit 3 is greater than _d1 and has two different number concentrations in one measurement cycle, so the current The square wave current whose high and low currents are _I1 and _I2 are induced in the meter 35. In addition, the charged aerosol particles with a particle diameter larger than _d2 will also induce a current in the ammeter 35 during the process of flowing through the first charge detection subunit 3, so the currents _I1 and _I2 not only include the particle diameter range of d ₁ <d<d ₂ The characteristic information of aerosol particles also includes the characteristic information of charged aerosol particles with a particle size larger than d ₂ .

The control unit 8 applies a constant voltage V ₄ on the electrode plate 41, and the constant voltage V ₄ causes an electric field with an intensity of E ₄ to be generated between the electrode plate 41 and the electrode plate 42, and the positive charge entering the second charge detection subunit 4 Under the action of the electric field E ₄ , the aerosol particles will be deflected towards the electrode plate 42, and an induced current will be induced in the ammeter 45 at the same time. The control unit 8 applies V ₄ corresponding to the second preset value d ₃ so that all charged aerosol particles entering the second charge detection sub-unit 4 are deposited on the electrode plate 42 . At the same time, due to the fluctuation of the concentration of charged aerosol particles with a particle diameter greater than d ₁ after flowing out of the deposition unit 2 due to the wave voltage above the deposition unit 2, and the intercepted particle diameter in the first charge detection subunit 3 is less than or equal to d ₂ . The effect of all aerosol particles, so that the particle size range of positively charged aerosol particles flowing into the second charge detection self-unit 4 is _d2 <d< _d3 and has two different number concentrations in one measurement cycle , so the square wave current with high and low currents of _I3 and _I4 is induced in the ammeter 45. Moreover, I ₃ and I ₄ only contain the characteristic information of charged aerosol particles with a particle size range of d ₂ <d<d ₃ .

The signal processing unit 9 obtains the induced currents I ₁ , I ₂ , I ₃ and I ₄ , and calculates the average particle size and number of aerosol particles with a particle size range of d ₁ <d<d ₂ according to the induced currents Concentration, and mean particle size and number concentration of aerosol particles in the size range d ₂ <d<d ₃ .

Since the measuring range of the aerosol sensor of the present invention has exceeded the range (10-300nm) of the linear relationship between the particle size and the charged amount in the Fuch diffusion charging theory, and the induced current I of the induction of the first charge detection subunit 3 ₁ and I ₂ are coupled with the information of charged aerosol particles with a particle size greater than d ₂ , so that the average particle size and number concentration of aerosol particles in the range of induced current I ₁ and I ₂ and d ₁ <d<d ₂ There is no common simple relational expression between them, so in the signal processing unit 8, the induced currents I ₁ and I ₂ on the first charge detection subunit 3 and the second charge The induced currents I ₃ and I ₄ on the detection subunit 4 are converted into the average particle size d _av,1 and the number concentration N ₁ of the aerosol particles with a particle size range of d ₁ <d<d ₂ and a particle size range of d ₂ < The average particle size d _av,2 and the number concentration N ₂ of the aerosol particles with d<d ₃ , the data fusion principle can be represented by the three-layer neural network structure shown in Figure 3 when using the neural network model, I ₁ and I ₂ and I ₃ and I ₄ constitute the input nodes of the network, and the average particle size d _av,1 , d _av,2 and number concentrations N ₁ and N ₂ constitute the output nodes of the network.

When the signal processing unit uses the BP neural network model for data fusion, the steps for establishing the BP neural network model include:

S1: collect the induced current obtained by measuring the calibration aerosol with the aerosol sensor, wherein the average particle size and number concentration of the calibration aerosol are known;

S2: Construct a BP neural network model, and calibrate the BP neural network model;

S3: Input each output induction current of the aerosol sensor into the calibrated BP neural network model to obtain the average particle diameter d _av,1 , d _av,2 and number concentration N ₁ , N ₂ of the aerosol particles.

Among them, before using the sensor to measure the aerosol, it is necessary to calibrate the parameters (W ₁ and W ₂ ) of the neural network model, that is, the parameter learning of the neural network. Step S2 includes:

S21: Construct a BP neural network model, and initialize the BP neural network model, including setting the initial values of the weighting parameters W ₁ and W ₂ of the BP neural network model;

S22: For the particle size and number concentration of the calibrated aerosol, m and n sample points are drawn respectively: d _av,1 , ..., d _av,m , N ₁ , ..., N _n , these sample points cover the aerosol The entire measurement range of the aerosol sensor, collecting the induced current obtained by the aerosol sensor measuring the calibration aerosol, specifically, will be in each known average particle size d _av,1 ,...,d _av,m and the number concentration N ₁ ,..., N _n collect and obtain each output current group of the aerosol sensor As a data sample, where i=1, 2,..., m, j=1, 2,..., n, the output current group is a group of induced currents;

S23: Use the BP learning algorithm to learn the weight parameters, input each output current group of the aerosol sensor into the learned BP neural network model, and obtain the average particle size and number concentration output by the BP neural network model;

S24: Correspondingly compare the output data of the BP neural network model with the average particle diameter and number concentration of the aerosol particles of the calibration aerosol, if the average particle diameter and quantity of the output of the BP neural network model If the error between the concentration and the average particle size and number concentration of the aerosol particles of the calibration aerosol is less than or equal to the second preset threshold, the calibration ends, otherwise, correct the weight parameters of the BP neural network model and return to S23; Wherein, the specific step of correcting the neural network parameters is to compare the average particle size and number concentration of the output of the BP neural network model with the average particle size and number concentration of the aerosol particles of the calibration aerosol correspondingly, according to The correction value [ΔW ₁ , ΔW ₂ ] of the weighting parameters W ₁ and W ₂ is calculated based on the principle of minimum mean square error of the error, and W ₁ +ΔW ₁ , W ₂ +ΔW ₂ are used as new weighting parameters.

After the calibration is completed, when the sensor is used to measure the average particle size and number concentration of the aerosol, the real-time collected current outputs I ₁ , I ₂ , I ₃ , and I ₄ are input to the neural network, and the output of the network model is to be Measure the average particle diameter d _av,1 , d _av,2 and the number concentration N ₁ , N ₂ of the aerosol particles.

The above-mentioned aerosol sensor uses a one-dimensional nanostructure such as a nanowire as the discharge anode in the aerosol tape electrical unit, and other electrode structures adopt a simple flat plate structure, which makes the sensor structure simple and easy to process, and can realize micromachining of the sensor, and further realize miniature The aerosol sensor meets the requirements of multi-point and distributed measurement of aerosol in a limited space.

It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is a relationship between these entities or operations. There is no such actual relationship or sequence. Furthermore, the term "comprises", "comprises" or any other variation thereof is intended to cover a non-exclusive inclusion such that a process, method, article or apparatus comprising a set of elements includes not only those elements, but also includes elements not expressly listed. other elements of or also include elements inherent in such a process, method, article, or device. Without more limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional same elements in the process, method, article or apparatus comprising said element.

Those of ordinary skill in the art can understand that all or part of the steps to realize the above method embodiments can be completed by program instructions related hardware, and the aforementioned programs can be stored in a computer-readable storage medium. When the program is executed, the It includes the steps of the above method embodiments; and the aforementioned storage medium includes: ROM, RAM, magnetic disk or optical disk and other various media that can store program codes.

Finally, it should be noted that the above descriptions are only preferred embodiments of the present invention, and are only used to illustrate the technical solution of the present invention, and are not used to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present invention are included in the protection scope of the present invention.

Claims (10)

1. An aerosol sensor, characterized in that, comprising: Aerosol inlet, aerosol charging unit, deposition unit, charge detection unit, control unit, signal processing unit, aerosol outlet; The aerosol inlet, the aerosol charging unit, the deposition unit, the charge detection unit, and the aerosol outlet are sequentially connected, the charge detection unit is connected to the signal processing unit, and the control unit is respectively connected to the deposition unit and the charge detection unit; The charge detection unit includes at least one charge detection subunit, the charge detection subunits are connected in sequence, each of the charge detection subunits is connected to the control unit, each of the charge detection subunits is respectively connected to the The signal processing unit is connected; The aerosol charging unit is used to charge the aerosol particles in the inflowing aerosol to be measured; The deposition unit is used to intercept the aerosol particles whose particle size is smaller than or equal to the initial preset value among the charged aerosol particles flowing in; The charge detection subunit is used to intercept the aerosol particles whose particle size is smaller than or equal to the preset value of the charge detection subunit in the charged aerosol particles flowing in, and output the generated induced current; The control unit is configured to apply a square wave voltage to the deposition unit according to the initial preset value, and apply the preset voltage to each of the charge detection subunits according to the preset value of each charge detection subunit. The constant voltage corresponding to the set value; The signal processing unit is used to calculate the average particle size and number concentration of the trapped aerosol particles in each charge detection subunit according to the induced currents and analytical expressions output by all the charge detection subunits, wherein, The analytical expression is a multivariate polynomial between the induced current, the average particle size, and the number concentration that meet the preset accuracy requirements; Or, the signal processing unit is used to calculate the average particle size and number concentration of the trapped aerosol particles in each charge detection subunit according to the induced current output by all the charge detection subunits and the neural network model, wherein , the neural network model is used to obtain the average particle size and the number concentration according to the input induced current; Wherein, the low level of the square wave voltage satisfies: among the charged aerosol particles flowing into the deposition unit, aerosol particles with a particle size smaller than or equal to the initial preset value are all trapped in the deposition unit; The high level of the square wave voltage satisfies: among the charged aerosol particles flowing into the deposition unit, all the aerosol particles whose particle size is smaller than or equal to the initial preset value are all trapped in the deposition unit, and Part of the aerosol particles whose particle size is larger than the initial preset value is also trapped in the deposition unit; The constant voltage corresponding to the preset value of the charge detection subunit satisfies: among the charged aerosol particles flowing into each of the charge detection subunits, all the aerosol particles whose particle diameter is smaller than or equal to the preset value of the charge detection subunit Trapped in said charge detection subunit; Wherein, at least one of all the preset values is greater than the initial preset value. 2. The aerosol sensor according to claim 1, wherein a filter membrane is installed in the aerosol inlet, and the filter membrane is used to filter out aerosol particles with a particle size greater than or equal to a preset particle size threshold, The preset particle size threshold is equal to a maximum preset value. 3. The aerosol sensor according to claim 1, wherein the aerosol electrified unit is a pin-plate ion source, the positive pole of the pin-plate ion source is a conductive tip, and the negative pole is a flat plate electrode. 4. The aerosol sensor according to claim 3, wherein the conductive tip comprises: a conductive one-dimensional nanostructure, an insulating one-dimensional nanostructure whose surface is covered with a metal layer, and a surface covered with a metal layer One-dimensional nanostructures of semiconductors. 5. The aerosol sensor according to claim 4, wherein the one-dimensional nanostructure comprises: nanowires, nanotubes, and nanorods. 6. The aerosol sensor according to claim 1, wherein the aerosol tape electrical unit is a line-barrel ion source, the anode of the line-barrel ion source is a conductive filament, and the negative pole is a cylinder electrode. 7. The aerosol sensor according to claim 1, wherein the deposition unit comprises two parallel electrode plates, one of which is grounded, and the other electrode plate is connected to the control unit. 8. The aerosol sensor according to claim 1, wherein each of the charge detection subunits comprises two parallel electrode plates and an ammeter, wherein one electrode plate is connected to the control unit, and the other electrode plate The board is connected with an ammeter, and the ammeter is connected with the signal processing unit, and the ammeter is used for measuring the induced current and outputting the magnitude of the measured induced current. 9. The aerosol sensor according to claim 1, characterized in that the charge detection subunit connected to the aerosol outlet is a Faraday cage or a Faraday disk. 10. The aerosol sensor according to claim 1, characterized in that, the aerosol sensor further comprises: a drive unit for driving the aerosol to be measured to flow in the aerosol sensor, the drive unit and the aerosol sensor The aerosol inlet is connected, or the driving unit is connected with the aerosol outlet.