A portable aerosol particle size spectrometer and its measurement method

Abstract

The present invention provides a portable aerosol particle size spectrometer and a measurement method thereof. The particle size spectrometer includes a photoelectric sensor, a signal filtering and amplifying circuit, a high-speed comparator, a peak value storage circuit, a high-speed AD sampling circuit, and a microprocessor. The photoelectric sensor is connected to the signal input end of the signal filtering and amplifying circuit, the signal output end of the signal filtering and amplifying circuit is connected to the high-speed comparator and the peak value storage circuit, respectively. The high-speed comparator is connected to the microprocessor, and the peak value storage circuit is connected to the microprocessor via the high-speed AD sampling circuit. Using the particle size spectrometer and measurement method of the present invention, rapid sampling can be achieved, the accuracy of particle concentration calculation can be improved, and the particle size spectrum of atmospheric particulate matter can be measured.

Description

Technical Field

[0001] The present invention relates to the technical field of environmental monitoring, and in particular to a portable aerosol particle size spectrometer and a measurement method thereof. Background Art

[0002] Aerosols are a mixed gaseous dispersion system composed of atmospheric, solid, or liquid particles. Aerosol particles are nanometer and submicrometer in size, typically ranging from 10nm to 10μm. Aerosols are characterized by small size, large surface area, high reactivity, and a tendency to carry toxic and harmful substances. They also remain in the atmosphere for a long time. Large particles are directly removed by the nasal cavity and throat, while the proportion of small particles deposited in the lungs and bronchi increases as their size decreases. They then enter the bloodstream and can cause diseases related to cardiopulmonary dysfunction.

[0003] Currently, particle detection in aerosols primarily involves measuring physical parameters, namely, particle number concentration and particle size distribution. Particle size distribution determines the inherent characteristics of aerosols, providing researchers with insights into their properties and helping them analyze their impacts. Measuring the size and number concentration of nano- and submicron-sized particles in aerosols (particle number spectra) is widely used in various fields. In particular, in environmental protection and meteorological research, the distribution of aerosol number spectra can be used to identify the source of atmospheric particulate matter, providing a basis for controlling particulate pollution. Aerosol particle size spectrometers are also widely used in performance testing of related products. For example, evaluating the clean air quality of air purifiers, measuring the filtration efficiency of face masks, and measuring the particle size and concentration of automobile exhaust particles all require corresponding aerosol size distribution and number concentration measurement systems.

[0004] Currently, several common particle size measurement methods are used in domestic and international research on atmospheric particulate matter distribution: optical, aerodynamic, and electrical methods. These methods measure the optical equivalent diameter, aerodynamic diameter, and electrical migration diameter of particles, respectively. Optical measurement instruments include optical particle counters (OPCs). Their operating principle is that laser light scatters from particles, which are focused by a reflector. A detector positioned on the same horizontal plane and at a certain angle to the laser direction receives the scattered light pulses. The number and intensity of these pulses are used to measure particle number concentration and particle size. These instruments have the advantages of a simple structure, relatively low price, low weight, and portability. Aerodynamic measurement instruments include aerodynamic particle size spectrometers (APSs). Their operating principle is to use aerodynamics to classify particles based on their inertial properties, and then measure their size and concentration. This method also offers high measurement accuracy, but it also suffers from issues such as complex instrumentation, high cost, bulky equipment, and strict operating conditions. Instruments that use electrical measurement methods include the Scanning Mobility Particle Sizer (SMPS). Its working principle is: the particle diameter obtained by measuring the electrical mobility of the particles is called the electrical mobility diameter. This method can efficiently measure particle concentration, has high measurement accuracy, and is capable of many particle size classifications. However, the problems are that the instrument has a complex structure, is expensive, and is bulky. In addition, the charged neutralizer in the instrument contains radioactive substances, requires strict operating specifications, and the equipment is difficult to be widely promoted.

[0005] Micro-scale optical particle counters are widely used due to their lightweight and portable nature. They measure the intensity and number of pulse signals generated by a photoelectric sensor through a signal acquisition circuit, mapping this information to aerosol particle size and concentration, or particle size distribution. The principle of particle size channel measurement is that each corresponding particle size channel discriminates, amplifies, compares, and counts the signal received by the photoelectric sensor based on its amplitude. Existing optical particle counters have independent hardware measurement levels for each particle size range. Particle size channels primarily include single-channel (measuring only a single particle size), dual-channel (measuring two particle sizes), and multi-channel (typically six channels: 0.3μm, 0.5μm, 1.0μm, 3.0μm, 5.0μm, and 10μm). However, particle size spectrometers require at least 16 particle size ranges. Existing optical particle counters offer a maximum of 16 particle size ranges, which falls short of the required channel count, impacting measurement accuracy and limiting particle count and concentration measurements. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a portable aerosol particle size spectrometer and a measurement method thereof, which can realize rapid sampling and provide accurate particle size classification and particle concentration calculation.

[0007] In a first aspect, the present invention provides a portable aerosol particle size spectrometer, comprising a photoelectric sensor, a signal filtering and amplifying circuit, a high-speed comparator, a peak value storage circuit, a high-speed AD sampling circuit, and a microprocessor;

[0008] The photoelectric sensor is connected to the signal input end of the signal filtering and amplifying circuit, the signal output end of the signal filtering and amplifying circuit is respectively connected to the high-speed comparator and the peak value storage circuit, the high-speed comparator is connected to the microprocessor, and the peak value storage circuit is connected to the microprocessor through a high-speed AD sampling circuit.

[0009] Furthermore, the photoelectric sensor includes an air path cavity, an optical path emitting unit, a silicon photodiode, a concave mirror, a convex lens, an aperture and a light trap. The optical path emitting unit is used to emit a parallel laser beam. The laser beam passes through the particulate matter in the air path cavity to generate scattered light. The scattered light passes through the concave mirror, the convex lens, the aperture in turn to the silicon photodiode. The silicon photodiode is used to receive the scattered light, and the light trap is used to absorb the laser beam.

[0010] Furthermore, the optical path emitting unit includes a laser and a lens group. The laser is a semiconductor red laser with a power of 30mW and a wavelength of 632nm. The laser beam of the laser emits a parallel laser beam after passing through the lens group.

[0011] Furthermore, the signal filtering and amplifying circuit includes a low-pass filtering circuit and a signal amplifying circuit. The photoelectric sensor converts the received scattered light into a pulse signal, removes noise through the low-pass filtering circuit, and then adjusts the signal output range to 0~12V through the signal amplifying circuit.

[0012] Furthermore, the particle size spectrometer also includes a first voltage follower and a second voltage follower. The signal filter amplification circuit is connected to the high-speed comparator via the first voltage follower, and the signal filter amplification circuit is connected to the peak storage circuit via the second voltage follower. The voltage follower can buffer, isolate, and increase the signal carrying capacity, thereby preventing the two signals from interfering with each other.

[0013] Furthermore, a digital-to-analog conversion circuit is connected between the microprocessor and the high-speed comparator. The digital-to-analog conversion circuit outputs a voltage value as a reference voltage for the high-speed comparator. When the voltage of the received pulse signal exceeds the reference voltage of the digital-to-analog conversion circuit, the high-speed comparator outputs a TTL-level pulse signal to the microprocessor. When the voltage of the received pulse signal is lower than the reference voltage of the digital-to-analog conversion circuit, the high-speed comparator maintains a low output level. When the microprocessor receives the rising edge of the pulse, it performs interrupt processing, executes a cumulative counting operation, and simultaneously starts the high-speed AD sampling circuit to measure the peak value of the pulse signal.

[0014] Furthermore, the peak preservation circuit includes an amplifying buffer operational circuit, an energy storage capacitor and an operational transconductance amplifier. The energy storage capacitor is respectively connected to the amplifying buffer operational circuit and the operational transconductance amplifier. The amplifying buffer operational circuit is connected to the operational transconductance amplifier. When the control signal pin is at a high level, the energy storage capacitor is maintained and reflected at the output end. The amplifying buffer operational circuit charges the energy storage capacitor to realize voltage sampling. During the sampling period, the operational transconductance amplifier is turned off, and the energy storage capacitor remains charged until it reaches the maximum value of the input voltage, maintaining the peak voltage of the input signal. At this time, the voltage value collected by the high-speed AD sampling circuit is the peak voltage value of the pulse. When the control signal pin is at a low level, the operational transconductance amplifier is turned on, and the energy storage capacitor is discharged outward, completing a peak holding timing, waiting for the arrival of the next pulse signal.

[0015] In a second aspect, the present invention provides a method for measuring a portable aerosol particle size spectrometer, which requires providing the particle size spectrometer described above, and the method comprises the following steps:

[0016] Step 1: The sample gas is sucked into the photoelectric sensor, and when the photoelectric sensor receives scattered light from particles, a pulse signal is generated;

[0017] Step 2: The pulse signal is filtered and amplified by a filter amplifier circuit;

[0018] Step 3: The pulse signal is then divided into two independent original pulse signals through two voltage followers, and input into a high-speed comparator and a peak value storage circuit respectively;

[0019] Step 4: When the voltage of an original pulse signal received by the high-speed comparator exceeds the reference voltage, a TTL level pulse signal is output to the microprocessor. When the voltage of an original pulse signal received by the high-speed comparator is lower than the reference voltage, the high-speed comparator always outputs a low level, and the original pulse signal is converted into a standard TTL level pulse signal by the high-speed comparator.

[0020] Step 5: The TTL level pulse signal is connected to the IO interrupt port of the microprocessor, and when a pulse rising edge comes, the microprocessor generates an interrupt, accumulates the count, and simultaneously starts the high-speed AD sampling circuit to measure the peak value of the pulse signal;

[0021] Step 6: When the original pulse signal passes through the peak value storage circuit, the peak time of the pulse signal is extended, and at the same time, the analog-to-digital conversion is performed through the high-speed AD sampling circuit to convert the peak voltage of the pulse signal into a digital value. The high-speed AD sampling circuit is used to perform analog-to-digital conversion and collect the peak value of the pulse signal. After the AD collection is completed, the peak value storage circuit of the pulse signal is reset and the next pulse signal is awaited.

[0022] Step 7: The peak voltage and corresponding number of the collected signal are matched and calculated with the particle size channel through the internal particle size classification algorithm of the microprocessor to obtain the particle concentration distribution of each particle size channel and draw it into a particle size spectrum. The particle size channel is pre-set with its corresponding particle size range.

[0023] Furthermore, in step 7, "the particle size channel pre-sets its corresponding particle size range" specifically includes: by using six standard polystyrene particles of 0.3μm, 0.5μm, 1μm, 3μm, 5μm, and 10μm as standard substances, after atomization, calibrating the voltage value of the pulse signal peak corresponding to the particle size channel of the particle size spectrometer, and after calibration, calculating the peak voltage values ​​corresponding to the other 42 particle size channels through a fitting algorithm, and obtaining 48 sets of corresponding relationships between particle size and voltage values.

[0024] Furthermore, the step 7 further includes:

[0025] The mass concentration values ​​of PM1.0, PM2.5 and PM10 are calculated based on the particle size spectrum using the following particle mass concentration formula:

[0026]

[0027] Among them, M n It represents the sum of the mass concentrations of particles in n particle size channels, and n represents the total number of particle size channels. represents the average radius of spherical particles in the i-th particle size channel, represents the average density of particles in the i-th particle size channel, N i represents the number of particles in the i-th particle size channel;

[0028] The above calculation results are compared with the calculation results of standard PM1.0, PM2.5, and PM10 measuring devices to obtain the concentration correction factor K. The particle concentration value calculated by the above particle mass concentration formula is multiplied by the correction factor K to obtain the corrected particle concentration value.

[0029] The advantages of the present invention are:

[0030] 1. The aerosol particle size measurement device based on the optical method is small in size and provides a portable measuring instrument;

[0031] 2. The peak value of the pulse signal generated by the photoelectric sensor is collected through a high-speed AD chip to obtain the corresponding voltage value, and the pulse is captured by a high-speed comparator to realize pulse counting. Through calibration and fitting, the graded calculation of more particle size channels is realized, the calculation accuracy and efficiency of particle mass concentration are improved, and the measurement of the particle size spectrum of atmospheric particulate matter is realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0033] Figure 1 The figure is a schematic diagram of the logical structure of a portable aerosol particle size spectrometer of the present invention.

[0034] Figure 2 Schematic diagram of the structure of the photoelectric sensor of the present invention

[0035] Figure 3 FIG. 4 is a schematic diagram showing the principle of a peak preservation circuit in one embodiment of the present invention.

[0036] Figure 4 FIG. 1 is a schematic diagram of a high-speed AD sampling circuit in one embodiment of the present invention.

[0037] Figure 5 FIG. 1 is a schematic diagram of a digital-to-analog conversion circuit in an embodiment of the present invention.

[0038] Figure 6 Schematic diagram of the pulse processing process of the present invention.

[0039] Figure 7 Schematic diagram of the corresponding relationship between voltage and particle size in 48 particle size channels divided in one embodiment of the present invention.

[0040] Figure 8 This is a flow chart of the execution of a measurement method of a portable aerosol particle size spectrometer of the present invention.

[0041] Figure 9 This is a particle size spectrum effect diagram under different particle size channels obtained in one embodiment of the present invention (the horizontal axis is the particle size channel, and the vertical axis is the particle concentration). DETAILED DESCRIPTION

[0042] See also Figures 1 to 7 , a portable aerosol particle size spectrometer of the present invention includes a photoelectric sensor, a signal filtering and amplifying circuit, a high-speed comparator, a peak value storage circuit, a high-speed AD sampling circuit and a microprocessor;

[0043] The photoelectric sensor is connected to the signal input end of the signal filtering and amplifying circuit, the signal output end of the signal filtering and amplifying circuit is respectively connected to the high-speed comparator and the peak value storage circuit, the high-speed comparator is connected to the microprocessor, and the peak value storage circuit is connected to the microprocessor through a high-speed AD sampling circuit.

[0044] Better, such as Figure 2 As shown, the photoelectric sensor includes an air path cavity 21, an optical path emitting unit 22, a silicon photodiode 23, a concave mirror 24, a convex lens 25, an aperture 26, and a light trap 27. The optical path emitting unit 22 is used to emit a parallel laser beam 28. The laser beam 28 passes through the particles 29 in the air path cavity to generate scattered light. The scattered light passes through the concave mirror 24, the convex lens 25, and the aperture 26 in sequence to the silicon photodiode 23. The silicon photodiode 23 serves as a receiver for receiving the scattered light, and the light trap 27 is used to absorb the laser beam. When in use, the gas to be measured can be sucked into the air inlet of the air path cavity by a vacuum pump and discharged from the air outlet of the air path cavity. In the figure, the x-axis is the laser irradiation direction, the y-axis is the gas flow direction, and the z-axis is the scattered light receiving direction. The three directions are perpendicular to each other.

[0045] The optical path emitting unit 22 includes a laser 221 and a lens group 222 . The laser 221 is a semiconductor red laser with a power of 30 mW and a wavelength of 632 nm. The laser beam of the laser emits a parallel laser beam after passing through the lens group 222 .

[0046] Preferably, the signal filtering and amplifying circuit includes a low-pass filtering circuit and a signal amplifying circuit. The photoelectric sensor converts the received scattered light into a pulse signal, removes noise through the low-pass filtering circuit, and then adjusts the signal output range to 0-12V through the signal amplifying circuit.

[0047] Preferably, the particle size spectrometer further includes a first voltage follower and a second voltage follower. The signal filter amplification circuit is connected to the high-speed comparator via the first voltage follower, and the signal filter amplification circuit is connected to the peak storage circuit via the second voltage follower. The voltage follower can buffer, isolate, and increase the signal's carrying capacity, thereby preventing mutual interference between the two signals.

[0048] Preferably, a digital-to-analog conversion (DAC) circuit is further connected between the microprocessor and the high-speed comparator. The digital-to-analog conversion (DAC) circuit outputs a voltage value as a reference voltage for the high-speed comparator. When the voltage of the received pulse signal exceeds the reference voltage of the digital-to-analog conversion (DAC) circuit, the high-speed comparator outputs a TTL-level pulse signal to the microprocessor. When the voltage of the received pulse signal is lower than the reference voltage of the digital-to-analog conversion (DAC) circuit, the high-speed comparator maintains a low output level. When the microprocessor receives a rising edge of the pulse, it performs interrupt processing, executes a cumulative counting operation, and simultaneously starts the high-speed AD sampling circuit to measure the peak value of the pulse signal.

[0049] Better, such as Figure 3 As shown, the peak preservation circuit includes an amplifying buffer operation circuit (SOTA), an energy storage capacitor (C2) and an operational transconductance amplifier (OTA). The energy storage capacitor is respectively connected to the amplifying buffer operation circuit (SOTA) and the operational transconductance amplifier (OTA). The amplifying buffer operation circuit (SOTA) is connected to the operational transconductance amplifier (OTA). When the control signal pin is high, the energy storage capacitor is maintained and reflected at the output end. The amplifying buffer operation circuit charges the energy storage capacitor to realize voltage sampling. During the sampling period, the operational transconductance amplifier is turned off, and the energy storage capacitor remains charged until it reaches the maximum value of the input voltage, maintaining the peak voltage of the input signal. At this time, the voltage value collected by the high-speed AD sampling circuit is the peak voltage value of the pulse. When the control signal pin is low, the operational transconductance amplifier is turned on, the energy storage capacitor is discharged outward, completing a peak holding timing, and waiting for the arrival of the next pulse signal.

[0050] See also Figures 1 to 9 The present invention provides a method for measuring a portable aerosol particle size spectrometer, which requires providing the particle size spectrometer described above. The method comprises the following steps:

[0051] Step 1: The sample gas is sucked into the photoelectric sensor, and when the photoelectric sensor receives scattered light from particles, a pulse signal is generated;

[0052] Step 2: The pulse signal is filtered and amplified by a filter amplifier circuit;

[0053] Step 3: The pulse signal is then divided into two independent original pulse signals through two voltage followers, and input into a high-speed comparator and a peak value storage circuit respectively;

[0054] Step 4: When the voltage of an original pulse signal received by the high-speed comparator exceeds the reference voltage, a TTL level pulse signal is output to the microprocessor. When the voltage of an original pulse signal received by the high-speed comparator is lower than the reference voltage, the high-speed comparator always outputs a low level, and the original pulse signal is converted into a standard TTL level pulse signal by the high-speed comparator.

[0055] Step 5: The TTL level pulse signal is connected to the IO interrupt port of the microprocessor, and when a pulse rising edge comes, the microprocessor generates an interrupt, accumulates the count, and simultaneously starts the high-speed AD sampling circuit to measure the peak value of the pulse signal;

[0056] Step 6: When the original pulse signal passes through the peak value storage circuit, the peak time of the pulse signal is extended, and at the same time, the analog-to-digital conversion is performed through the high-speed AD sampling circuit to convert the peak voltage of the pulse signal into a digital value. The high-speed AD sampling circuit is used to perform analog-to-digital conversion and collect the peak value of the pulse signal. After the AD collection is completed, the peak value storage circuit of the pulse signal is reset and the next pulse signal is awaited.

[0057] Step 7: Using the microprocessor's internal particle size classification algorithm, the peak voltage and corresponding number of the collected signal are matched and calculated with the particle size channels to obtain the particle concentration distribution for each particle size channel, which is then plotted as a particle size spectrum. As shown in Figure 6, Figure (a) shows the original pulse. After filtering and amplification, Figure (b) is obtained. The number of pulse peaks corresponding to each particle size channel is then calculated based on the particle size corresponding to each channel, resulting in Figure (c).

[0058] Preferably, in step 7, "presetting the corresponding particle size range of the particle size channel" specifically includes: using six standard polystyrene particles such as 0.3μm, 0.5μm, 1μm, 3μm, 5μm, and 10μm as standard substances, after atomization, calibrating the voltage value of the pulse signal peak corresponding to the particle size channel of the particle size spectrometer, and after calibration, calculating the peak voltage values ​​corresponding to the other 42 particle size channels by a fitting algorithm, and obtaining 48 sets of corresponding relationships between particle size and voltage values, such as Figure 7 For example, a 12-bit high-speed AD can collect up to 4096 particle size channel pulses. The voltage compression of the 4096 particle size channel pulses can be converted into the corresponding 48 groups of aerosol particle size distributions through the internal classification unit of the microprocessor, and the calculated concentration graph of each particle size channel can be output to the user, as shown in the figure below. Figure 9 shown.

[0059] Preferably, the step 7 further comprises:

[0060] The mass concentration values ​​of PM1.0, PM2.5 and PM10 are calculated based on the particle size spectrum using the following particle mass concentration formula:

[0061]

[0062] Among them, M n It represents the sum of the mass concentrations of particles in n particle size channels, and n represents the total number of particle size channels. represents the average radius of spherical particles in the i-th particle size channel, represents the average density of particles in the ith particle size channel, assuming that the optical diameter and kinetic diameter of the corresponding channel are consistent, for example, the average density value is 1g / cm 3 , N i represents the number of particles in the i-th particle size channel;

[0063] The above calculation results are compared with the calculation results of standard PM1.0, PM2.5, and PM10 measuring devices to obtain the concentration correction factor K. The particle concentration value calculated by the above particle mass concentration formula is multiplied by the correction factor K to obtain the corrected particle concentration value.

[0064] The present invention is an aerosol particle size measuring device based on an optical method. The device is small in size and provides a portable measuring instrument. Laser irradiation on particulate matter causes scattering, which is focused by a reflector. A receiving unit receives the scattered light pulse signal, and based on the number and strength of the pulse signal, the particle number concentration and particle size are measured. A high-speed AD chip is used to collect the peak value of the pulse signal generated by the photoelectric sensor to obtain the corresponding voltage value, and a high-speed comparator is used to capture the pulse to achieve pulse counting. A particle size distribution diagram of the actual required number of particle size channels can be obtained through partial calibration and partial fitting. Then, an iterative recursive algorithm of the particle size spectrum is used to design an inversion algorithm for the particle concentration, and the mass concentrations of PM10, PM2.5 and PM1 can be calculated. Through correction, a more accurate particle concentration value calculation formula is obtained, further improving the instrument's particle concentration detection accuracy.

[0065] Although the specific embodiments of the present invention are described above, those skilled in the art should understand that the specific embodiments described are merely illustrative and are not intended to limit the scope of the present invention. Equivalent modifications and changes made by those skilled in the art in accordance with the spirit of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for measuring a portable aerosol particle size spectrometer, characterized in that: The method comprises the following steps: Step 1: The sample gas is sucked into the photoelectric sensor. When the photoelectric sensor receives the scattered light from the particles, a pulse signal is generated. Step 2: The pulse signal is filtered and amplified by a filter amplifier circuit; Step 3: The pulse signal is then divided into two independent original pulse signals through two voltage followers, and input into a high-speed comparator and a peak value storage circuit respectively; Step 4: When the voltage of an original pulse signal received by the high-speed comparator exceeds the reference voltage, a TTL level pulse signal is output to the microprocessor. When the voltage of an original pulse signal received by the high-speed comparator is lower than the reference voltage, the high-speed comparator always outputs a low level, and the original pulse signal is converted into a standard TTL level pulse signal by the high-speed comparator. Step 5: The TTL level pulse signal is connected to the IO interrupt port of the microprocessor, and when a pulse rising edge comes, the microprocessor generates an interrupt, accumulates the count, and simultaneously starts the high-speed AD sampling circuit to measure the peak value of the pulse signal; Step 6: When the original pulse signal passes through the peak value storage circuit, the peak time of the pulse signal is extended, and at the same time, the analog-to-digital conversion is performed through the high-speed AD sampling circuit to convert the peak voltage of the pulse signal into a digital value. The high-speed AD sampling circuit is used to perform analog-to-digital conversion and collect the peak value of the pulse signal. After the AD collection is completed, the peak value storage circuit of the pulse signal is reset and the next pulse signal is awaited. Step 7: Using the microprocessor's internal particle size classification algorithm, the peak voltage and corresponding number of the collected signal are matched and calculated with the particle size channel to obtain the particle concentration distribution of each particle size channel and plot it into a particle size spectrum. The particle size channel is pre-set with its corresponding particle size range; In step 7, "the particle size channel is pre-set to its corresponding particle size range" specifically includes: using six standard polystyrene particles of 0.3μm, 0.5μm, 1μm, 3μm, 5μm, and 10μm as standard substances, after atomization, calibrating the voltage value of the pulse signal peak corresponding to the particle size channel of the particle size spectrometer, and after calibration, calculating the peak voltage values ​​corresponding to the other 42 particle size channels through a fitting algorithm, and obtaining 48 sets of corresponding relationships between particle size and voltage values.

2. The method for measuring a portable aerosol particle size spectrometer according to claim 1, wherein: The step 7 further comprises: The mass concentration values ​​of PM1.0, PM2.5 and PM10 are calculated based on the particle size spectrum using the following particle mass concentration formula: ； in, It represents the sum of the mass concentrations of particles in n particle size channels, and n represents the total number of particle size channels. represents the average radius of spherical particles in the i-th particle size channel, represents the average density of particles in the i-th particle size channel, represents the number of particles in the i-th particle size channel; The above calculation results are compared with the calculation results of standard PM1.0, PM2.5, and PM10 measuring devices to obtain the concentration correction factor K. The particle concentration value calculated by the above particle mass concentration formula is multiplied by the correction factor K to obtain the corrected particle concentration value.

3. A portable aerosol particle size spectrometer for performing the method according to claim 1 or 2, characterized in that: It includes a photoelectric sensor, a signal filtering and amplifying circuit, a high-speed comparator, a peak value storage circuit, a high-speed AD sampling circuit and a microprocessor; The photoelectric sensor is connected to the signal input end of the signal filtering and amplifying circuit, the signal output end of the signal filtering and amplifying circuit is respectively connected to the high-speed comparator and the peak value storage circuit, the high-speed comparator is connected to the microprocessor, and the peak value storage circuit is connected to the microprocessor through the high-speed AD sampling circuit; The particle size spectrometer further includes a first voltage follower and a second voltage follower, the signal filtering and amplifying circuit is connected to the high-speed comparator via the first voltage follower, and the signal filtering and amplifying circuit is connected to the peak value storage circuit via the second voltage follower; A digital-to-analog conversion circuit is further connected between the microprocessor and the high-speed comparator. The digital-to-analog conversion circuit outputs a voltage value as a reference voltage for the high-speed comparator. When the voltage of the received pulse signal exceeds the reference voltage of the digital-to-analog conversion circuit, the high-speed comparator outputs a TTL-level pulse signal to the microprocessor. When the voltage of the received pulse signal is lower than the reference voltage of the digital-to-analog conversion circuit, the high-speed comparator maintains a low output level. When the microprocessor receives a rising edge of the pulse, it performs an interrupt process, executes a cumulative counting operation, and simultaneously starts a high-speed AD sampling circuit to measure the peak value of the pulse signal. A high-speed AD chip is used to collect the peak value of the pulse signal generated by the photoelectric sensor to obtain the corresponding voltage value, and a high-speed comparator is used to capture the pulse to realize pulse counting. The particle size distribution diagram of the actually required number of particle size channels is obtained through partial calibration and partial fitting.

4. The portable aerosol particle size spectrometer according to claim 3, characterized in that: The photoelectric sensor includes an air path cavity, an optical path emitting unit, a silicon photodiode, a concave mirror, a convex lens, an aperture and a light trap. The optical path emitting unit is used to emit a parallel laser beam. The laser beam generates scattered light when passing through the particles in the air path cavity. The scattered light passes through the concave mirror, the convex lens, the aperture in sequence to the silicon photodiode. The silicon photodiode is used to receive the scattered light, and the light trap is used to absorb the laser beam.

5. The portable aerosol particle size spectrometer according to claim 4, characterized in that: The optical path emitting unit includes a laser and a lens group. The laser adopts a semiconductor red laser with a power of 30mW and a wavelength of 632nm. The laser beam of the laser emits a parallel laser beam after passing through the lens group.

6. The portable aerosol particle size spectrometer according to claim 3, characterized in that: The signal filtering and amplifying circuit includes a low-pass filtering circuit and a signal amplifying circuit. The photoelectric sensor converts the received scattered light into a pulse signal, removes noise through the low-pass filtering circuit, and then adjusts the signal output range to 0~12V through the signal amplifying circuit.

7. The portable aerosol particle size spectrometer according to claim 3, characterized in that: The peak preservation circuit includes an amplifying buffer operation circuit, an energy storage capacitor and an operational transconductance amplifier. The energy storage capacitor is respectively connected to the amplifying buffer operation circuit and the operational transconductance amplifier. The amplifying buffer operation circuit is connected to the operational transconductance amplifier. When the control signal pin is at a high level, the energy storage capacitor is maintained and reflected at the output end. The amplifying buffer operation circuit charges the energy storage capacitor to realize voltage sampling. During the sampling period, the operational transconductance amplifier is turned off, and the energy storage capacitor remains charged until it reaches the maximum value of the input voltage, maintaining the peak voltage of the input signal. At this time, the voltage value collected by the high-speed AD sampling circuit is the peak voltage value of the pulse. When the control signal pin is at a low level, the operational transconductance amplifier is turned on, the energy storage capacitor is discharged outward, completing a peak holding timing, and waiting for the arrival of the next pulse signal.

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