Laser ionization method of aerosol mass spectrometer and aerosol mass spectrometer

Abstract

The invention discloses a laser ionization method of an aerosol mass spectrometer and the aerosol mass spectrometer. The method comprises the following steps: acquiring flight time and pulse signals corresponding to each detected particle, and obtaining the probability that each particle is a biological fluorescent particle according to the pulse signals and / or the flight time; wherein the pulse signal at least comprises a fluorescent pulse signal, or the pulse signal at least comprises a fluorescent pulse signal and a scattered light pulse signal; the ionization triggering time corresponding to each particle is calculated through the flight time; the ionization triggering moments are sequenced according to the probability from large to small; according to the sequence, performing laser ionization on the target particles at the ionization triggering moment of the target particles; wherein the probability of the target particles is maximum. In this way, the pulse utilization rate of the ionization laser can be improved, and therefore the detection sensitivity of the aerosol mass spectrometer is improved.

Description

Technical Field

[0001] The present application relates to the technical field of aerosol detection, and in particular to a laser ionization method of an aerosol mass spectrometer and an aerosol mass spectrometer. Background Art

[0002] Aerosol mass spectrometers are widely used in the field of aerosol research. They analyze and identify the chemical composition of aerosol particles in real time and with high resolution, and can also measure the size of aerosol particles. Aerosol mass spectrometers generally use ionization lasers as ionization sources.

[0003] The disadvantage is that the triggering frequency of the ionization laser will cause idle time between the pulsed lasers. During this time, the ionization laser cannot be triggered, which leads to a decrease in the detection sensitivity of the aerosol mass spectrometer to bioaerosols. Summary of the invention

[0004] The laser ionization method of an aerosol mass spectrometer and the aerosol mass spectrometer provided in the present application can improve the pulse utilization rate of the ionization laser, thereby improving the detection sensitivity of the aerosol mass spectrometer.

[0005] In a first aspect, the present application provides a laser ionization method for an aerosol mass spectrometer, the method comprising: obtaining a flight time and a pulse signal corresponding to each detected particle, and obtaining a probability that each particle is a bioluminescent particle based on the pulse signal and / or the flight time; wherein the pulse signal at least includes a fluorescent pulse signal, or the pulse signal at least includes a fluorescent pulse signal and a scattered light pulse signal; using the flight time to calculate an ionization trigger moment corresponding to each particle; sorting the ionization trigger moments from large to small according to probability; according to the sorting, at the ionization trigger moment of the target particle, laser ionizing the target particle; wherein the probability of the target particle is the largest.

[0006] Wherein, the probability of each particle being a bioluminescent particle is obtained based on the pulse signal and / or flight time, including: calculating the relationship between the fluorescence pulse signal and the flight time of each particle; or, calculating the relationship between the fluorescence pulse signal and the scattered light pulse signal of each particle; or, calculating the relationship between the fluorescence pulse signal, the scattered light pulse signal and the flight time of each particle; and comparing the relationship with the prior probability to obtain the probability of each particle being a bioluminescent particle.

[0007] The prior probability is obtained in the following manner: collecting pure environmental background particle samples and pure bioaerosol particle samples without bioaerosol; obtaining the first target flight time and the first target pulse signal of the pure environmental background particle samples; and obtaining the second target flight time and the second target pulse signal of the pure bioaerosol particle samples; and determining the prior probability according to the first target flight time, the first target pulse signal, the second target flight time and the second target pulse signal.

[0008] Among them, the flight time includes a first flight time and a second flight time; obtaining the flight time and pulse signal corresponding to each detected particle includes: obtaining the first flight time and pulse signal corresponding to each detected particle; using the first flight time to determine the second flight time; using the flight time to calculate the ionization trigger time corresponding to each particle, including: using the second flight time to calculate the ionization trigger time corresponding to each particle.

[0009] The method of determining the second flight time by using the first flight time includes: determining a flight time range for a corresponding target particle to reach a next light source by using the first flight time; and determining the second flight time based on the flight time range.

[0010] In response to the fact that the pulse signal of the next light source corresponding to the target particle is not collected within the flight time range, the information of the target particle is cleared.

[0011] In which, in response to collecting pulse signals of the next light source corresponding to multiple target particles within the flight time range, the correspondence between the particles is determined by using the difference between the collection time corresponding to the pulse signals of the next light source of the multiple target particles and the time center of the flight time range corresponding to the multiple target particles.

[0012] Among them, the target particles are sorted according to the bioluminescence trigger probability and laser ionized at the ionization trigger moment of the target particles, including: when the ionization trigger moment of any particle is reached, detecting whether the current particle is the target particle; if so, laser ionizing the current particle; if not, clearing the information of the current particle in the sorting.

[0013] Among them, performing laser ionization on the current particle includes: obtaining the state of the ionization laser; in response to the state being a waiting trigger state, performing laser ionization on the current particle; in response to the state being a disabled state, clearing the information of the current particle in the sorting.

[0014] In a second aspect, the present application provides an aerosol mass spectrometer, which includes: an optical device for generating at least two light sources; a collection module for collecting the flight time and pulse signals of each particle passing through the at least two light sources successively; and a processing module for utilizing the flight time and pulse signals to implement the method provided in the first aspect.

[0015] The optical device includes: a first optical device for generating two light sources; a second optical device for generating one light source; and a third optical device for generating ionizing laser.

[0016] The beneficial effect of the present application is as follows: different from the prior art, the laser ionization method and aerosol mass spectrometer of the present application use the fluorescence pulse signal of each particle to obtain the probability of each particle being a bioluminescent particle, and sort the ionization triggering time of each particle from large to small according to the probability of each particle being a bioluminescent particle; then select the particle with the highest probability as the target of laser ionization, and perform laser ionization on the particle, so that the ionization laser can more likely hit the bioaerosol particle, improve the pulse utilization rate of the ionization laser, and thus improve the detection sensitivity of the aerosol mass spectrometer. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. Among them: Figure 1 It is a structural schematic diagram of an embodiment of an aerosol mass spectrometer provided by the present application; Figure 2 It is a schematic flow chart of an embodiment of a laser ionization method for an aerosol mass spectrometer provided in the present application; Figure 3 It is a schematic flow chart of another embodiment of the laser ionization method of the aerosol mass spectrometer provided by the present application; Figure 4 It is a schematic flow chart of another embodiment of the laser ionization method of the aerosol mass spectrometer provided by the present application; Figure 5 It is a schematic flow chart of another embodiment of the laser ionization method of the aerosol mass spectrometer provided by the present application; Figure 6 It is a schematic diagram of the relationship between the fluorescence pulse signal and the scattered light signal provided by the present application; Figure 7 It is a schematic diagram of the relationship between the fluorescence pulse signal and the flight time provided in the present application; Figure 8 is a structural schematic diagram of another embodiment of the aerosol mass spectrometer provided by the present application; Fig. 9 is a structural schematic diagram of another embodiment of the aerosol mass spectrometer provided by the present application; Fig.10It is a schematic flow chart of another embodiment of the laser ionization method of the aerosol mass spectrometer provided by the present application; Fig.11 It is a partial structural schematic diagram of the aerosol mass spectrometer provided in this application.

[0018] In the figure: 100, aerosol mass spectrometer; 10, optical device; 20, acquisition module; 30, processing module; 101, first optical device; 1011, first continuous laser; 1012, first lens group; 1013, wave plate; 1014, beam splitter; 102, second optical device; 1021, second continuous laser; 1022, second lens group; 103, third optical device; 1031, ionization laser; 1032, third lens group; 2, aperture; 3, spherical reflector; 4, extinction cone; 5, first convex lens; 6, dichroic mirror; 7, second convex lens; 8, scattered light acquisition unit; 9, filter; 11, third convex lens; 12, fluorescence acquisition unit. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. It will be understood that the specific embodiments described herein are only used to explain the present application, rather than to limit the present application. It should also be noted that, for ease of description, only some but not all structures related to the present application are shown in the drawings. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0020] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0021] Aerosol mass spectrometers are widely used in the field of aerosol research. They analyze and identify the chemical composition of aerosol particles in real time and with high resolution, and can also measure the size of aerosol particles. Aerosol mass spectrometers generally use ionization lasers as ionization sources.

[0022] The disadvantage is that the triggering frequency of the ionization laser will cause idle time between pulsed lasers, during which the laser cannot be triggered, which leads to a decrease in the detection sensitivity of the aerosol mass spectrometer to bioaerosols.

[0023] Based on this, the present application proposes to use the fluorescence pulse signal of each particle to obtain the probability of each particle being a bioluminescent particle, and to sort the ionization triggering moment of each particle from large to small according to the probability of each particle being a bioluminescent particle; then select the particle with the highest probability as the target of laser ionization, and perform laser ionization on the particle, so that the ionization laser can more likely hit the bioaerosol particles, improve the pulse utilization rate of the ionization laser, and thus improve the detection sensitivity of the aerosol mass spectrometer. For details, refer to any of the following embodiments or a combination of any embodiments.

[0024] See also Figure 1 , Figure 1 1 is a schematic diagram of the structure of an embodiment of an aerosol mass spectrometer provided in the present application. The aerosol mass spectrometer 100 comprises: an optical device 10 , a collection module 20 and a processing module 30 .

[0025] The optical device 10 is used to generate two light sources.

[0026] The collection module 20 is used to collect the flight time and pulse signals of aerosol particles passing through at least two light sources in sequence.

[0027] The processing module 30 is used to utilize the flight time and the pulse signal to implement a method provided in any of the following embodiments.

[0028] In some embodiments, the aerosol mass spectrometer is a single particle aerosol mass spectrometer.

[0029] In some embodiments, the optical device 10 is functionally equivalent to a first diameter measuring laser. In other embodiments, the aerosol mass spectrometer 100 further includes an ionization laser for emitting laser light to perform laser ionization on target particles.

[0030] See also Figure 2 , Figure 2 1 is a flow chart of an embodiment of a laser ionization method for an aerosol mass spectrometer provided in the present application. The method comprises: Step 21: Obtain the flight time and pulse signal corresponding to each detected particle, and obtain the probability that each particle is a bioluminescent particle based on the pulse signal and / or the flight time.

[0031] In some embodiments, the pulse signal includes at least a fluorescence pulse signal.

[0032] In some embodiments, the pulse signal includes at least a fluorescence pulse signal and a scattered light pulse signal.

[0033] In some embodiments, the flight time indicates the time length of time that a particle passes through two light sources. For example, the flight time is determined using scattered light pulse signals generated by the particle passing through the two light sources.

[0034] In some embodiments, a dichroic mirror can be used to separate the light generated by the particles passing through two light sources into fluorescence and scattered light, thereby obtaining corresponding fluorescence pulse signals and scattered light pulse signals.

[0035] Therefore, the probability of each particle being a bioluminescent particle can be obtained based on the fluorescence pulse signal of each particle. For example, the probability of the bioluminescent particle corresponding to the particle is determined based on the signal intensity of the fluorescence pulse signal. The greater the probability of the bioluminescent particle, the greater the probability that the particle is a bioaerosol.

[0036] Step 22: Calculate the ionization triggering time corresponding to each particle using the flight time.

[0037] In some embodiments, the ionization triggering time corresponding to each particle can be estimated based on the positional relationship between the light source position corresponding to the flight time and the ionization laser. The ionization triggering time indicates the time when the particle enters the ionization range of the ionization laser and the ionization laser can be used to ionize the particle.

[0038] Step 23: Sort the ionization triggering moments according to probability from large to small.

[0039] In some embodiments, during the time from the calculation of the flight time of a particle to the time it enters the ionization range of the ionization laser, there are actually multiple particles that also have corresponding flight times. That is, the corresponding ionization triggering moments and the bioluminescent particle probabilities corresponding to these particles can also be calculated.

[0040] Based on this, the ionization triggering moments can be sorted from large to small according to probability.

[0041] In some embodiments, the following is described in conjunction with Table 1: Table 1: Sorting table

[0042] As shown in Table 1, the probability of particle A being a bioluminescent particle is 90%, and the corresponding ionization triggering time is T2. The probability of particle B being a bioluminescent particle is 85%, and the corresponding ionization triggering time is T1. The probability of particle C being a bioluminescent particle is 80%, and the corresponding ionization triggering time is T3. Among them, T1 is earlier than T2, and T2 is earlier than T3.

[0043] Step 24: According to the order, at the ionization triggering moment of the target particle, the target particle is laser ionized; among them, the probability of the target particle is the largest.

[0044] In some embodiments, the following is described in conjunction with Table 1: At T1, the probability of the corresponding particle B being a bioluminescent particle is 85%, which is not the maximum probability, so the particle B is not laser ionized at this time, that is, the ionization laser is not triggered.

[0045] At T2, the probability of the corresponding particle A being a bioluminescent particle is 90%, which is the highest probability. At this time, the particle A is laser ionized, that is, the ionization laser is triggered.

[0046] It can be understood that, due to the large number of particles, the probability ranking is constantly updated, and particles that have passed the ionization triggering moment will be removed from Table 1 to ensure the accuracy of subsequent probability comparisons that have not reached the ionization triggering moment.

[0047] In this embodiment, the probability of each particle being a bioluminescent particle is obtained by utilizing the fluorescence pulse signal of each particle, and the ionization triggering moment of each particle is sorted from large to small according to the probability of each particle being a bioluminescent particle; then the particle with the highest probability is selected as the target of laser ionization, and the particle is laser ionized, so that the ionization laser can more likely hit the bioaerosol particles, thereby improving the pulse utilization rate of the ionization laser, thereby improving the detection sensitivity of the aerosol mass spectrometer.

[0048] See also Figure 3 , Figure 3 1 is a flow chart of another embodiment of the laser ionization method for an aerosol mass spectrometer provided in the present application. The method comprises: Step 41: Obtain the flight time and pulse signal corresponding to each detected particle, and calculate the relationship between the fluorescence pulse signal and the flight time of each particle.

[0049] In some embodiments, the pulse signal includes at least a fluorescence pulse signal.

[0050] In some embodiments, the pulse signal includes at least a fluorescence pulse signal and a scattered light pulse signal.

[0051] In some embodiments, the ratio between the fluorescence pulse signal and the flight time may be used as the relationship between the fluorescence pulse signal and the flight time.

[0052] Step 42: Compare the relationship and the prior probability to obtain the probability that each particle is a bioluminescent particle.

[0053] In some embodiments, the prior probability can be determined in advance. Therefore, the relationship and the prior probability can be compared to obtain the probability that each particle is a bioluminescent particle.

[0054] Step 43: Calculate the ionization triggering time corresponding to each particle using the flight time.

[0055] Step 44: Sort the ionization triggering moments according to the probability from large to small.

[0056] Step 43-Step 44 has the same or similar technical solutions as any embodiment of the present application.

[0057] Step 45: According to the order, at the ionization triggering moment of the target particle, the target particle is laser ionized; wherein the probability of the target particle is the largest.

[0058] In some embodiments, when the ionization triggering moment of any particle is reached, it is detected whether the current particle is a target particle; if so, the current particle is laser ionized; if not, the information of the current particle is cleared from the sorting.

[0059] This is explained in conjunction with Table 1: T1 is earlier than T2, and T2 is earlier than T3.

[0060] At T1, the probability of the corresponding particle B being a bioluminescent particle is 85%, which is not the highest probability. In this case, the particle B is not laser ionized. That is, particle B is not the target particle, and the ionization laser is not triggered. The information of particle B is cleared in the sorting.

[0061] At T2, the probability of the corresponding particle A being a bioluminescent particle is 90%, which is the highest probability. At this time, the particle A is laser ionized. That is, particle A is the target particle, and the ionization laser is triggered. After the ionization laser is triggered, the information of particle A is cleared from the sorting.

[0062] In some embodiments, ionization is performed in the following manner: acquiring the state of the ionization laser; in response to the state being a waiting trigger state, performing laser ionization on the current particle; in response to the state being a disabled state, clearing the information of the current particle in the sort.

[0063] That is, when the ionization triggering moment of reaching the target particle is determined, the state of the ionization laser is obtained. In response to the state being the waiting trigger state, the ionization laser can be triggered to perform laser ionization on the current particle. After excitation, the state of the ionization laser is changed from the waiting trigger state to the disabled state. In response to the state being the disabled state, the ionization laser cannot be triggered, and the information of the current particle is cleared in the sorting.

[0064] The duration of the disabled state is the idle time mentioned above. When the duration of the disabled state reaches the idle time, the state of the ionization laser can be changed from the disabled state to the waiting trigger state.

[0065] In this embodiment, the probability of each particle being a bioluminescent particle is obtained by utilizing the fluorescence pulse signal of each particle, and the ionization triggering moment of each particle is sorted from large to small according to the probability of each particle being a bioluminescent particle; then the particle with the highest probability is selected as the target of laser ionization, and the particle is laser ionized, so that the ionization laser can more likely hit the bioaerosol particles, thereby improving the pulse utilization rate of the ionization laser, thereby improving the detection sensitivity of the aerosol mass spectrometer.

[0066] See also Figure 4 , Figure 4 1 is a flow chart of another embodiment of the laser ionization method for an aerosol mass spectrometer provided in the present application. The method comprises: Step 51: Obtain the flight time and pulse signal corresponding to each detected particle, and calculate the relationship between the fluorescence pulse signal and the scattered light pulse signal of each particle.

[0067] In some embodiments, the pulse signal includes at least a fluorescence pulse signal.

[0068] In some embodiments, the pulse signal includes at least a fluorescence pulse signal and a scattered light pulse signal.

[0069] In some embodiments, the ratio between the fluorescence pulse signal and the scattered light pulse signal may be used as the relationship between the fluorescence pulse signal and the scattered light pulse signal.

[0070] Step 52: Compare the relationship and the prior probability to obtain the probability that each particle is a bioluminescent particle.

[0071] In some embodiments, the prior probability can be determined in advance. Therefore, the relationship and the prior probability can be compared to obtain the probability that each particle is a bioluminescent particle.

[0072] Step 53: Calculate the ionization triggering time corresponding to each particle using the flight time.

[0073] Step 54: Sort the ionization triggering moments according to the probability from large to small.

[0074] Step 55: According to the order, at the ionization triggering moment of the target particle, the target particle is laser ionized; wherein the probability of the target particle is the largest.

[0075] Step 53 to step 55 have the same or similar technical solutions as any embodiment of the present application.

[0076] In this embodiment, the probability of each particle being a bioluminescent particle is obtained by utilizing the fluorescence pulse signal of each particle, and the ionization triggering moment of each particle is sorted from large to small according to the probability of each particle being a bioluminescent particle; then the particle with the highest probability is selected as the target of laser ionization, and the particle is laser ionized, so that the ionization laser can more likely hit the bioaerosol particles, thereby improving the pulse utilization rate of the ionization laser, thereby improving the detection sensitivity of the aerosol mass spectrometer.

[0077] See also Figure 5 , Figure 5 1 is a flow chart of another embodiment of the laser ionization method for an aerosol mass spectrometer provided in the present application. The method comprises: Step 61: Obtain the flight time and pulse signal corresponding to each detected particle, and calculate the relationship between the fluorescence pulse signal, scattered light pulse signal and flight time of each particle.

[0078] In some embodiments, the pulse signal includes at least a fluorescence pulse signal.

[0079] In some embodiments, the pulse signal includes at least a fluorescence pulse signal and a scattered light pulse signal.

[0080] In some embodiments, the ratio among the fluorescence pulse signal, the scattered light pulse signal and the flight time may be used as the relationship among the fluorescence pulse signal, the scattered light pulse signal and the flight time.

[0081] Step 62: Compare the relationship and the prior probability to obtain the probability that each particle is a bioluminescent particle.

[0082] In some embodiments, the prior probability can be determined in advance. Therefore, the relationship and the prior probability can be compared to obtain the probability that each particle is a bioluminescent particle.

[0083] Step 63: Calculate the ionization triggering time corresponding to each particle using the flight time.

[0084] Step 64: Sort the ionization triggering moments according to the probability from large to small.

[0085] Step 65: According to the order, at the ionization triggering moment of the target particle, the target particle is laser ionized; wherein the probability of the target particle is the largest.

[0086] Step 63 to step 65 have the same or similar technical solutions as any embodiment of the present application.

[0087] In this embodiment, the probability of each particle being a bioluminescent particle is obtained by utilizing the fluorescence pulse signal of each particle, and the ionization triggering moment of each particle is sorted from large to small according to the probability of each particle being a bioluminescent particle; then the particle with the highest probability is selected as the target of laser ionization, and the particle is laser ionized, so that the ionization laser can more likely hit the bioaerosol particles, thereby improving the pulse utilization rate of the ionization laser, thereby improving the detection sensitivity of the aerosol mass spectrometer.

[0088] In some embodiments, the prior probability is obtained in the following manner: collect pure environmental background particle samples and pure bioaerosol particle samples without bioaerosol; obtain the first target flight time and the first target pulse signal of the pure environmental background particle sample; and obtain the second target flight time and the second target pulse signal of the pure bioaerosol particle sample; determine the prior probability according to the first target flight time, the first target pulse signal, the second target flight time, and the second target pulse signal. The first target pulse signal includes the fluorescent pulse signal and the scattered light pulse signal collected by the optical device. The second target pulse signal includes the fluorescent pulse signal and the scattered light pulse signal collected by the optical device. The first target flight time and the second target flight time are the time when the particle passes through the first optical device 101 described below in the present application.

[0089] Combination Figure 6 and Figure 7 According to the distribution of fluorescence pulse signal, scattered light pulse signal and particle size of pure environmental background particles and pure bioaerosol particles, the probability distribution of the credibility of the particles being bioaerosol particles can be calculated. P = N 生物 / ( N 环境 + N 生物 ).in N 生物 Indicates the number of pure bioaerosol particles in the intensity range of the pulse signal, N 环境 Indicates the number of pure environmental background particles in the intensity range of the pulse signal.

[0090] Table 2: Probability distribution of bioaerosols

[0091] As shown in Table 2, its specific meaning is: the probability that a particle is a bioaerosol when the fluorescence pulse signal and scattered light pulse signal are within a specific intensity range. The first vertical column represents the intensity range of the fluorescence pulse signal, the last horizontal row represents the intensity range of the scattered light pulse signal, and the remaining positions represent the probability of the particle corresponding to the bioaerosol (biofluorescent particle).

[0092] See also Figure 8 , Figure 8 1 is a schematic diagram of the structure of another embodiment of the aerosol mass spectrometer provided by the present application. The aerosol mass spectrometer 100 includes: an optical device 10, a collection module 20 and a processing module 30. The optical device 10 includes: a first optical device 101, a second optical device 102 and a third optical device 103. Among them, the first optical device 101 is used to generate two light sources. The second optical device 102 is used to generate a light source. The third optical device 103 is used to generate an ionizing laser.

[0093] The collection module 20 is used to collect the flight time and pulse signals of aerosol particles passing through at least two light sources in sequence.

[0094] The processing module 30 is used to utilize the flight time and the pulse signal to implement the method provided in any embodiment of the present application.

[0095] In some embodiments, functionally, the first optical device 101 is equivalent to a first diameter measuring laser, the second optical device 102 is equivalent to a second diameter measuring laser, and the third optical device 103 is equivalent to an ionizing laser.

[0096] In some embodiments, Fig. 9 As shown, the first optical device 101 has a first continuous laser 1011. The laser emitted by the first continuous laser 1011 is emitted to the beam splitter 1014 through the first lens group 1012 and the wave plate 1013. Two laser beams are separated by the beam splitter 1014, so as to calculate the first flight time using the two laser beams. The second optical device 102 has a second continuous laser 1021. The laser emitted by the second continuous laser 1021 is emitted through the second lens group 1022. The second flight time can be calculated using the laser emitted by the second optical device 102 and the second laser beam in the first optical device 101. The third optical device 103 has an ionization laser 1031 and a third lens group 1032. The ionization laser 1031 emits an ionization laser, which passes through the lens group and irradiates a predetermined position. The ionization trigger time corresponding to each particle can be calculated according to the distance between the third optical device 103 and the second optical device 102.

[0097] See also Fig.10 , Fig.101 is a flow chart of another embodiment of the laser ionization method for an aerosol mass spectrometer provided in the present application. The method comprises: Step 111: Obtain the first flight time and pulse signal corresponding to each detected particle, and obtain the probability that each particle is a bioluminescent particle according to the pulse signal and / or the first flight time.

[0098] In some embodiments, the pulse signal includes at least a fluorescence pulse signal.

[0099] In some embodiments, the pulse signal includes at least a fluorescence pulse signal and a scattered light pulse signal.

[0100] In some embodiments, the first flight time indicates the duration of time that the particle passes through the two light sources generated by the first optical device 101. For example, the first flight time is determined using scattered light pulse signals generated by the particle passing through the two light sources.

[0101] In some embodiments, a dichroic mirror can be used to separate the light generated by the particles passing through two light sources into fluorescence and scattered light, thereby obtaining corresponding fluorescence pulse signals and scattered light pulse signals.

[0102] Therefore, the probability that each particle is a bioluminescent particle can be obtained according to the fluorescence pulse signal of each particle. For example, the probability that the particle is a bioluminescent particle can be determined according to the signal intensity of the fluorescence pulse signal.

[0103] In some embodiments, the relationship between the fluorescent pulse signal and the first flight time of each particle may be calculated, and the relationship may be compared with the prior probability to obtain the probability that each particle is a bioluminescent particle.

[0104] In some embodiments, the relationship between the fluorescence pulse signal and the scattered light pulse signal of each particle can be calculated, and the relationship can be compared with the prior probability to obtain the probability that each particle is a bioluminescent particle.

[0105] In some embodiments, the relationship between the fluorescence pulse signal, the scattered light pulse signal and the first flight time of each particle can be calculated, and the relationship can be compared with the prior probability to obtain the probability that each particle is a bioluminescent particle.

[0106] Step 112: Determine a second flight time using the first flight time.

[0107] The second flight time indicates the time it takes for the particle to reach the second optical device from the first optical device.

[0108] In some embodiments, the first flight time is used to determine the flight time range of the corresponding target particle to the next light source; based on the flight time range, in response to collecting a pulse signal of a target particle corresponding to the next light source within the flight time range, a second flight time is determined, wherein the next light source refers to a beam of light generated by the second optical device.

[0109] In response to the fact that the pulse signal of the next light source corresponding to the target particle is not collected within the flight time range, the information of the target particle is cleared. If the pulse signal of the next light source corresponding to the target particle is not collected within the flight time range, it means that the pulse signal of the target particle may be lost, and therefore, the information of the target particle can be cleared.

[0110] In which, in response to the pulse signals of the next light source corresponding to the multiple target particles collected within the flight time range, the corresponding relationship between the particles is determined by using the pulse signals of the previous light source of the multiple target particles. In the case of a relatively high particle concentration, the flight time range of the multiple particles arriving at the second optical device may have an aliasing phenomenon, and the time difference between the center position of the flight time range generated by the multiple particles and the pulse signal (scattered light pulse signal) actually arriving at the next light source position can be compared, and the time difference is generally minimized to correspond to the particles passing through the first optical device. For example, the corresponding relationship between the particles is determined by using the difference between the time center of the flight time range corresponding to the multiple target particles at the collection time corresponding to the pulse signal of the next light source. The flight time range of the two particles arriving at the second optical device 102 may have an aliasing phenomenon, and the difference between the time center of the corresponding flight time range calculated by the two particles can be minimized to correspond to the particles passing through the first optical device 101. For example: Particle A and particle B correspond to pulse signal a1 and pulse signal b1 through the first optical device, and particle A and particle B correspond to pulse signal a2 and pulse signal b2 through the second optical device. However, it is currently unknown whether pulse signal a1 corresponds to pulse signal a2 or pulse signal b2, and whether pulse signal b1 corresponds to pulse signal a2 or pulse signal b2. Therefore, the flight time range corresponding to particle A and particle B can be obtained. For example, the flight time range corresponding to particle A is range F1, and the flight time range corresponding to particle B is range F2. Then calculate the first time center corresponding to range F1 and the second time center corresponding to range F2. Then calculate the first difference between the acquisition time of pulse signal a2 and the first time center, and calculate the second difference between the acquisition time of pulse signal b2 and the first time center. If the first difference is less than the second difference, pulse signal a2 corresponds to pulse signal a1, and pulse signal b2 corresponds to pulse signal b1. If the first difference is greater than the second difference, pulse signal a2 corresponds to pulse signal b1, and pulse signal b2 corresponds to pulse signal a1.

[0111] The above are just two examples, and three or more can be determined in this way.

[0112] In another embodiment, the pulse signals of multiple target particles at the previous light source and the pulse signals of multiple target particles at the next light source can be used to calculate the corresponding flight times to be determined between the particles passing through the previous light source and the next light source; the corresponding relationship between the particles is determined using the difference in the time centers corresponding to the flight times to be determined. For example, there is an aliasing phenomenon in the flight time range of particles A and B reaching the second optical device 102. Therefore, when two pulse signals are detected at the second optical device 102, it is impossible to distinguish the corresponding relationship between the two pulse signals and particles A and B. Therefore, four flight times to be determined are calculated respectively.

[0113] For example: Particle A and particle B correspond to pulse signal a1 and pulse signal b1 through the first optical device, and particle A and particle B correspond to pulse signal a2 and pulse signal b2 through the second optical device. However, it is currently unknown whether pulse signal a1 corresponds to pulse signal a2 or pulse signal b2, and it is unknown whether pulse signal b1 corresponds to pulse signal a2 or pulse signal b2. Therefore, the first flight time to be determined can be calculated by pulse signal a1 and pulse signal a2, the second flight time to be determined can be calculated by pulse signal a1 and pulse signal b2, the third flight time to be determined can be calculated by pulse signal b1 and pulse signal a2, and the fourth flight time to be determined can be calculated by pulse signal b1 and pulse signal b2.

[0114] Then, the first flight time to be determined and the third flight time to be determined are used as a group to calculate the difference between the flight time centers of the first flight time to be determined and the third flight time to be determined. The second flight time to be determined and the fourth flight time to be determined are used as a group to calculate the difference between the flight time centers of the second flight time to be determined and the fourth flight time to be determined.

[0115] By comparing the difference, a group of actual flight times is determined, and then the particles corresponding to the corresponding pulse signals are matched. For example, a group of flight times with the smallest difference is determined as the actual flight time, and then the particles corresponding to the corresponding pulse signals are matched.

[0116] Step 113: Calculate the ionization triggering time corresponding to each particle using the second flight time.

[0117] After the scattered light signal of the particle when it reaches the second optical device corresponds to the scattered light signal reaching the first optical device, the second flight time of the particle can be calculated. And according to the ratio relationship between the second flight time and the ionization trigger time, the ionization trigger time is calculated and stored in the memory space. The calculation method of the ratio relationship between the second flight time and the ionization trigger time is generally related to the ratio between the distance between the first optical device and the second optical device, and the distance between the second optical device and the ionization laser, and taking into account the delay time that the ionization laser needs to be actively pumped, generally the ionization trigger time = k*second flight time-delay.

[0118] Step 114: Sort the ionization triggering moments according to the probability from large to small.

[0119] Step 115: According to the order, at the ionization triggering moment of the target particle, the target particle is laser ionized; wherein the probability of the target particle is the largest.

[0120] In some embodiments, when the ionization triggering moment of any particle is reached, it is detected whether the current particle is a target particle; if so, the current particle is laser ionized; if not, the information of the current particle is cleared from the sorting.

[0121] This is explained in conjunction with Table 1: T1 is earlier than T2, and T2 is earlier than T3.

[0122] At T1, the probability of the corresponding particle B being a bioluminescent particle is 85%, which is not the highest probability. In this case, the particle B is not laser ionized. That is, particle B is not the target particle, and the ionization laser is not triggered. The information of particle B is cleared in the sorting.

[0123] At T2, the probability of the corresponding particle A being a bioluminescent particle is 90%, which is the highest probability. At this time, the particle A is laser ionized. That is, particle A is the target particle, and the ionization laser is triggered. After the ionization laser is triggered, the information of particle A is cleared from the sorting.

[0124] In some embodiments, ionization is performed in the following manner: acquiring the state of the ionization laser; in response to the state being a waiting trigger state, performing laser ionization on the current particle; in response to the state being a disabled state, clearing the information of the current particle in the sort.

[0125] That is, when the ionization triggering moment of reaching the target particle is determined, the state of the ionization laser is obtained. In response to the state being the waiting trigger state, the ionization laser can be triggered to perform laser ionization on the current particle. After excitation, the state of the ionization laser is changed from the waiting trigger state to the disabled state. In response to the state being the disabled state, the ionization laser cannot be triggered, and the information of the current particle is cleared in the sorting.

[0126] The duration of the disabled state is the idle time mentioned above. When the duration of the disabled state reaches the idle time, the state of the ionization laser can be changed from the disabled state to the waiting trigger state.

[0127] In this embodiment, the probability of each particle being a bioluminescent particle is obtained by utilizing the fluorescence pulse signal of each particle, and the ionization triggering moment of each particle is sorted from large to small according to the probability of each particle being a bioluminescent particle; then the particle with the highest probability is selected as the target of laser ionization, and the particle is laser ionized, so that the ionization laser can more likely hit the bioaerosol particles, thereby improving the pulse utilization rate of the ionization laser, thereby improving the detection sensitivity of the aerosol mass spectrometer.

[0128] In one application scenario, the sampled air enters the aerosol mass spectrometer 100 through an aerodynamic lens, and according to the structure of the aerosol mass spectrometer 100, the first flight time, scattered light pulse signal, and fluorescence pulse signal are obtained through the double-beam laser of the first optical device 101. The relationship between the particle scattered light pulse signal (or the first flight time) and the fluorescence intensity is calculated, and compared with the prior probability to obtain the probability that the particle is a bioluminescent particle, which is stored in the bioluminescence probability space.

[0129] The time when the particle reaches the position of the second optical device 102 can be calculated based on the first flight time. According to the preset calculation error value, the time range from the first optical device 101 to the second optical device 102 can be obtained, and the range is stored in the memory space corresponding to the second flight time. When the particle reaches the range of the second optical device 102, the scattered light pulse signal at this position is calculated with the scattered light pulse signal of the first optical device 101 corresponding to the particle to obtain an accurate second flight time. Therefore, the ionization triggering moment corresponding to the particle can be calculated based on the second flight time. In this process, due to the divergence problem of the aerodynamic lens on the aerosol (particle), the scattered light pulse signal of the particle may be lost. At this time, the data of the particle is discarded and the next particle is waiting to arrive at the position of the second optical device 102.

[0130] The timing algorithm is calculated by countdown method. That is, after reaching the position of the first optical device 101, the flight time range of the particle to the second optical device 102 is calculated, and countdown is performed. When the time reaches 0, it means that the particle enters the range of the second optical device 102, and the scattered light pulse signal generated by the second optical device 102 within the detection range is tested and associated with the scattered light pulse signal of the particle in the first optical device 101, and the accurate second flight time of the particle is calculated. Since the process is run in parallel, the time ranges of multiple particles are generally accumulated in this process and stored in the memory of the timing control card, and all particles are detected to see whether they have reached the position of the second optical device 102.

[0131] The above method has the beneficial effect that, because parallel computing is adopted, when the scattered light pulse signal is lost due to the aerodynamic lens divergence problem of aerosol (particles), the data of the particle is discarded, and the calculation of other particles is not affected. In addition, when the particle concentration is relatively high, the flight time range of two particles reaching the second optical device 102 may be aliased, and the difference between the centers of the flight time calculated by the two particles can be minimized to correspond to the particles passing through the first optical device 101.

[0132] After the scattered light pulse signal when the particle reaches the second optical device 102 corresponds to the scattered light pulse signal reaching the first optical device 101, the second flight time of the particle can be calculated. And according to the ratio relationship between the second flight time and the ionization trigger time, the ionization trigger time is calculated and stored in the memory space. The calculation method of the ratio relationship between the second flight time and the ionization trigger time is generally related to the ratio between the distance between the first optical device and the second optical device, and the distance between the second optical device and the ionization laser, and taking into account the delay time that the ionization laser needs to be actively pumped, generally the ionization trigger time = k*second flight time-delay.

[0133] Compared with the first-come-first-trigger method used in related technologies, that is, a particle first calculates the ionization trigger time, and then waits for the ionization trigger time to trigger the ionization laser. However, because the frequency of the ionization laser is low, it takes a long time to wait for the next particle to be ionized. The present application selects the particle with the highest probability for attack in advance during the period from the first optical device to the third optical device (ionization laser), according to the distribution relationship between the particle's fluorescence pulse signal and the scattered light pulse signal and the fluorescence pulse signal and the first flight time, thereby improving the detection sensitivity of bioaerosols.

[0134] Specifically, after the bioluminescent particle probability of the particle is calculated, it is stored in the memory and corresponds to the flight time of the particle. In the time range from the first optical device 101 to the position of the third optical device (ionization laser), multiple particles may pass through the first optical device 101 and generate multiple bioluminescent particle probabilities and the flight time of the particle. At this time, the bioluminescent particle probabilities are sorted, the triggering time of the ionization laser corresponds to the bioluminescent particle probability, and the particles are ionized and enter the mass analyzer to analyze the chemical composition of the particles, so as to accurately determine whether the particles are bioaerosol particles.

[0135] More specifically, after calculating the ionization triggering time, each particle waits for the particle to reach the ionization triggering position in a countdown method, and only the particle with the highest probability of biofluorescence will be triggered by the ionization laser. However, the premise for determining whether the ionization laser is triggered is that the laser is in a state of waiting for triggering. When the countdown time of a particle is zero, that is, the particle has reached the ionization laser position, because the ionization laser is not in a state of waiting for triggering, or the particle with the highest probability of biofluorescence is not the one with the highest probability, the ionization laser will not be triggered, and its data record will be released from the memory.

[0136] Because the time for the particles to travel from the first optical device 101 to the third optical device 103 is less than the idle time caused by the laser frequency of the third optical device 103. Under normal circumstances, the time from the first optical device 101 to the third optical device 103 is much smaller than the idle time caused by the laser frequency of the third optical device 103, so the particles that are most likely to be bioluminescent particles are struck within this time range, which will make full use of the pulse times of the ionizing laser, thereby increasing the detection rate and sensitivity of bioaerosols per unit time.

[0137] In some embodiments, the first optical device 101 is further configured with a corresponding collection unit and an optical path transmission device. Fig.11 As shown, in the optical path direction of the first optical device 101, an aperture 2, a spherical reflector 3, a first convex lens 5, a dichroic mirror 6, a second convex lens 7, a filter 9, a third convex lens 11, an extinction cone 4, a scattered light collection unit 8 and a fluorescence collection unit 12 are arranged. The light source of the first optical device 101 is incident on the extinction cone 4 through the aperture 2. When particles pass through the light source, they are scattered, generating corresponding scattered light and fluorescence. At this time, the scattered light and fluorescence are incident on the first convex lens 5 through the spherical reflector 3, and then incident on the dichroic mirror 6 from the first convex lens 5, and the scattered light and fluorescence are separated by the dichroic mirror 6. The scattered light is incident on the scattered light collection unit 8 through the second convex lens 7 to obtain a corresponding scattered light pulse signal. The fluorescence is incident on the fluorescence collection unit 12 through the third convex lens to obtain a corresponding fluorescence pulse signal.

[0138] In summary, the laser ionization method and aerosol mass spectrometer of the aerosol mass spectrometer provided by the present application use the fluorescence pulse signal of each particle to obtain the probability of each particle being a bioluminescent particle, and sort the ionization triggering time of each particle from large to small according to the probability of each particle being a bioluminescent particle; then select the particle with the highest probability as the target of laser ionization, and perform laser ionization on the particle, so that the ionization laser can more likely hit the bioaerosol particle, improve the pulse utilization rate of the ionization laser, and thus improve the detection sensitivity of the aerosol mass spectrometer.

[0139] In the several embodiments provided in this application, it should be understood that the disclosed methods and devices can be implemented in other ways. For example, the device implementation described above is only illustrative, for example, the division of the modules or units is only a logical function division, and there may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed.

[0140] If the integrated units in the above other embodiments are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions to enable a computer device (which can be a personal computer, server, or network device, etc.) or a processor to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, RandomAccess Memory), disk or optical disk and other media that can store program codes.

[0141] The above description is only an implementation method of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A laser ionization method for an aerosol mass spectrometer, characterized in that: The method comprises: Obtaining the flight time and pulse signal corresponding to each detected particle, wherein the pulse signal at least includes a fluorescent pulse signal, calculating the relationship between the fluorescent pulse signal and the flight time of each particle, and comparing the relationship with a priori probability to obtain the probability that each particle is a bioluminescent particle; Calculating the ionization triggering time corresponding to each particle using the flight time; sorting the ionization triggering moments according to the probabilities from large to small; According to the arrangement, at the ionization triggering moment of the target particle, the target particle is laser ionized; wherein the probability of the target particle is the largest.

2. The method according to claim 1, characterized in that: The prior probability is obtained in the following way: Collect pure environmental background particle samples without bioaerosol and pure bioaerosol particle samples; Acquire a first target flight time and a first target pulse signal of the pure environmental background particle sample; and acquire a second target flight time and a second target pulse signal of the pure bioaerosol particle sample; The prior probability is determined according to the first target flight time, the first target pulse signal, the second target flight time, and the second target pulse signal.

3. The method according to claim 1, characterized in that The flight time includes a first flight time and a second flight time; and obtaining the flight time and pulse signal corresponding to each detected particle includes: Acquire the first flight time and the pulse signal corresponding to each detected particle; determining the second flight time using the first flight time; The step of calculating the ionization triggering time corresponding to each particle by using the flight time includes: The second flight time is used to calculate the ionization triggering time corresponding to each particle.

4. The method according to claim 3, characterized in that The determining the second flight time by using the first flight time includes: Determine the flight time range of the corresponding target particle to reach the next light source using the first flight time; The second flight time is determined based on the flight time range.

5. The method according to claim 4, characterized in that In response to not collecting the pulse signal of the target particle corresponding to the next light source within the flight time range, the information of the target particle is cleared.

6. The method according to claim 4, characterized in that In response to collecting pulse signals of the next light source corresponding to multiple target particles within the flight time range, the correspondence between the particles is determined by using the difference between the collection moments corresponding to the pulse signals of the next light source of the multiple target particles and the time centers of the flight time ranges corresponding to the multiple target particles.

7. The method according to claim 1, characterized in that According to the arrangement, at the ionization triggering moment of the target particles, laser ionization is performed on the target particles, comprising: When the ionization triggering moment of any particle is reached, detecting whether the current particle is the target particle; If so, performing laser ionization on the current particle; If not, clear the information of the current particle in the sorting.

8. The method according to claim 7, characterized in that The laser ionization of the current particles comprises: Get the status of the ionization laser; In response to the state being a waiting trigger state, performing laser ionization on the current particle; In response to the state being a disabled state, clearing the information of the current particle in the sorting.

9. An aerosol mass spectrometer, characterized in that: The aerosol mass spectrometer comprises: An optical device for generating at least two light sources; A collection module, used for collecting the flight time and pulse signal of each particle passing through the at least two light sources successively; A processing module, used to utilize the flight time and the pulse signal to implement the method according to any one of claims 1-8.

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