JPS58165008A - Measurement of particle diameter distribution of micro particle - Google Patents

Abstract

PURPOSE:To measure the distribution of particle diameter by the analysis of it with a pulse height analyser, by a method wherein laser beam is focused in the micro particles travelling during floating in fluid from the direction meeting at a right angle to the travelling direction. CONSTITUTION:The laser beam 4 from a laser beam source 3 is focused in a fluid with a cylindrical lens 5, and the scattered light within a range of 40 deg.- 50 deg. in the direction oblique to the beam 4 among the scattered light due to a micro particle 2 in fluid is focused with a condenser 7. This light is passed through an iris 8, and sent to an optical detector 10 via an optical fiber 9. The detected change of pulse signal is compressed with logarithmic amplifier 12, and the distribution of diameter of micro particle passing through a focusing part 6 is measured by analysing it with the pulse height analyser 13 every pulse height. Therefore, the distribution of diameter of micro particle travelling during floating in fluid can be continuously measured in real time without disturbing the travelling of micro particle.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for measuring the particle size distribution of microparticles floating and moving in a liquid or gas.

One specific example of moving microparticles suspended in a fluid to serve a purpose is the inhalation administration of drug aerosols used in the treatment and diagnosis of respiratory diseases such as asthma in the medical field. In this case, it is necessary for treatment and diagnosis to know the amount of drug aerosol that is actually inhaled.At the same time, among the particles of drug aerosol inhaled, large particles are deposited in the upper bronchi, while relatively small particles are deposited in the upper bronchi. It is necessary to know the particle size distribution of drug aerosols, as smaller particles tend to be deposited in the distal bronchi and exhaled with exhalation. Therefore, it is important to measure the particle size distribution of a drug aerosol administered by inhalation during administration in order to know the amount of inhalation and the performance after inhalation of the drug aerosol.

BACKGROUND ART As methods for measuring the particle size distribution of microparticles suspended in fluids such as gases and liquids, sampling methods, particle counter methods, off-ellow meter methods, and the like are conventionally known. However, the sampling method involves attaching floating microparticles to a thin film of powder such as MgO or an oil film, and counting the number of traces and dragged particles under a microscope or by taking photographs, which takes time and effort. Furthermore, continuous real-time measurements of moving microparticles, such as measuring drug aerosols during inhalation, are not possible. In addition, the particle counter method requires particles to be ejected into a laser beam in a jet stream, and for this reason, in the case of volatile particles such as water droplets, particles that have become smaller due to evaporation are measured. There are drawbacks such as clutter.

In addition, the one-type nephelometer measures particles placed in a chamber by fixing them at one point in the laser beam using an electric field, so it is not suitable for continuously measuring a large number of moving particles. .

In contrast to these conventional measurement methods, the present invention continuously measures the particle size distribution of f-microparticles floating and moving in a fluid such as gas or liquid in real time without impairing the movement of microparticles. The purpose is to provide a measurement method that can

That is, the present invention focuses a laser beam through a lens on microparticles floating in a fluid and moving in a flow pipe from a direction substantially perpendicular to the direction of movement of the microparticles. Only the scattered light of the laser beam caused by the microparticles, the scattered light within a certain angle range in a certain diagonal direction with respect to the laser beam, is focused by a condenser lens to form an image of the microparticles. An iris is provided on the image plane to allow only the scattered light from the microparticles passing through the center of the light collecting section to pass through, this scattered light is detected by a photodetector, and the detected electrical signal is further amplified by a pulse amplifier. After that, each pulse height is sequentially analyzed by a pulse height analyzer to measure the particle size distribution of microparticles passing through the light condensing part 1
・Hereinafter, the present invention will be explained according to the drawings.

Figure 1 is a block diagram showing one embodiment of the present invention.
·· be. Reference numeral 1 denotes a flow path tube made of glass, in which fluid such as gas or liquid flows in the direction of the arrow.

2 is a microparticle suspended in a fluid; 3 is a laser light source that emits, for example, a He-Ne laser beam in a direction substantially perpendicular to the flow direction of the fluid; 4 is a laser beam emitted from the laser light source 3; 5 is a laser beam 4 is a cylindrical lens that focuses light into a strip in a direction approximately perpendicular to the direction of movement of the microparticles; 6 is a condenser for the laser beam 4 focused into the fluid by the cylindrical lens 5; and 7 is a condenser. Light part 6
Of the light scattered by the microparticles 2 passing through the laser beam 4, the direction is diagonal to the laser beam 4, preferably 40° to 500° forward.
A condensing lens 8 is provided on the image plane of the microparticles 2 formed by the condensing lens 7 to collect the scattered light in the range of . 9 is an optical fiber that guides the scattered light that has passed through the iris 8; 10 is a photodetector that detects the intensity of the scattered light guided by the optical fiber 9 and converts it into an electrical signal;
11 is a logarithmic amplifier for compressing the change in the pulse electric signal caused by the scattered light detected by the photodetector 10 and widening the measurement particle size range; 12 is a pulse amplifier for amplifying the signal from the logarithmic amplifier 11; 13 is a pulse A pulse height analyzer analyzes the pulse height of the pulse signal from the amplifier 12, and 14 is a display device such as an oscilloscope or a recorder that displays and records the results of the analysis by the pulse height analyzer 13.

As described above, this device detects the scattered light of the microparticles 2 passing through the light condensing section 6. Since only the scattered light of the microparticles 2 passing through the strip-shaped central part of the light condensing section 6 is detected through the iris 8, the laser beam 4 having a Gaussian intensity distribution, for example, is detected. It is possible to reduce the variation in the measured wave height value due to the scattering and detect the scattered light with higher accuracy.

Next, the intensity of the scattered light is detected by the photodetector 10, and the change in the pulse signal is compressed by the logarithmic amplifier 12. The purpose is to provide a correspondingly wider range and to facilitate the analysis of the particle size distribution.

Figure 2 shows a He-Ne laser with a wavelength of 0.6328 μm.
Among the scattered light of the water droplet microparticles with a refractive index of 1.337 caused by the beam, the light is scattered from 40 degrees diagonally forward to the laser beam.
This is the result of calculating the particle size dependence of the scattering cross section for scattered light in the range of 0.

From now on, for example, 40 degrees diagonally in front of the laser beam.
It can be seen that in the range from 50° to 50° overall, the scattering cross section has a nearly square relationship with the particle size. Similarly, even when the scattered light detection angle range is changed, the scattering cross section has a substantially constant relationship with the particle size.

Therefore, the intensity of the pulsed light signal from the microparticles 2 passing through the condensing section 6 is approximately proportional to the square of the particle size of the microparticles 2, and the pulsed electrical signal obtained by the photodetector 10 is transmitted to the pulse height analyzer. 13, the particle size distribution can be measured by analyzing, for example, 100 channels.

Figure 3 is a graph showing the measurement results of the particle size distribution of water droplet microparticles sprayed by a nebulizer with a small compressor completely turned off.The horizontal axis shows the pulse height when the pulse signal of the measured particles was analyzed with a pulse height analyzer. 100 channels are displayed, and the vertical axis indicates the number of particles measured.

FIG. 4 is a graph showing the measurement results when the same sprayed water droplet microparticles as in FIG. 3 were measured by the sampling method (immersion method).

From these FIGS. 3 and 4, it can be seen that the peak near channel 50 in FIG. 3 corresponds to a diameter of approximately 2 μm. Therefore, by measuring the pulse height of microparticles whose particle size is known in advance, the actual particle size distribution can be immediately determined from the pulse height obtained by the pulse height analyzer.

Figure 5 is a graph showing the results of particle size distribution measurements taken in real time at the patient's mouth after spraying physiological saline from a nebulizer driven by a small compressor and administering the atomized air to the patient by inhalation. Figure □° ”□ ((A) is during inhalation, and Fig. 5 (B) is during expiration. Inhalation or exhalation was measured 20 times each, and the amount of blown particle distribution inhaled or exhaled was integrated. Figure 5 (C) is the fifth
The difference between Figures (A) and (B) shows the particle size distribution corresponding to the amount of inhaled atomized microparticles that are deposited in the respiratory system. This causes extremely small particles to be exhaled again during exhalation.
For the first time, actual measurements confirmed the conventional assumption that relatively large particles are deposited in the respiratory system.

As described above, in the measurement method according to the present invention, the space to be measured in the condensing part of the laser beam is determined by the overlap between the laser beam and the field of view of the receiving optical system. Since the particle size distribution of microparticles can be measured or monitored in real time, the particle size distribution and amount of microparticles in a fluid can be easily controlled.

In addition, if the cross-sectional area of the measurement space and the flow pipe through which the microparticles move is determined in advance, the total volume or total weight of the microparticles that have moved within the flow pipe can be calculated from the measurement results of the particle size distribution. It has unprecedented features such as being able to easily and in real time.

Although the present invention has been described above according to the embodiments, the present invention is not limited thereto. For example, the laser beam may have an appropriate wavelength and output1, and the lens for condensing the laser beam may be used as necessary. Lenses of other shapes than cylindrical lenses may be used, and the microparticles to be measured may be liquids, solids, or gases such as bubbles, and the fluid in which the microparticles to be measured move may be gas, In addition to liquids, vacuum may also be used, and the scattered light to be detected among the scattered light by microparticles is at an angle of 40 degrees in front of the laser beam.
The present invention is not limited to scattered light in the range of ~50°, but scattered light in other suitable angle ranges may be detected. Also, although not mentioned in the explanation, if noise is generated during measurement due to other floating particles or air bubbles in the fluid other than the microparticles to be measured, perform a blank measurement with only the microparticles to be measured removed. The actual particle size distribution of the desired microparticles may be obtained by subtracting this particle size distribution as noise from the actually measured particle size distribution measurement results, or the noise may be removed using other electrical circuit methods. good.

Further, the channel tube through which the fluid flows may be made of glass or other metal, but in that case, a window or the like that allows laser beams or scattered light to pass through may be provided and measurements may be made through this window.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a graph showing the particle size dependence of the scattering cross section in the diagonal 45° direction due to changes in the scattering angle of water droplets, and Fig. 3 is a graph showing the particle size A graph showing the measurement results of the diameter distribution, Figure 4 shows the sampling method (
FIG. 5(A) is a graph showing the measurement results of the particle size distribution of water droplet particles by the liquid immersion method. (B) and (B) are graphs showing the particle size distribution measurement results measured in real time at the patient's mouth when physiological saline was sprayed from a nebulizer driven by a small compressor and the atomized air was inhaled and administered to the patient. be. 1... Channel pipe 2... Microparticles 3... Laser light source 5... Cylindrical shape... 6...] Light condensing part T...
Focusing...Z890. Eye+7, C9,,, ゛eye 2'-1010, yeah□. , J 4"l. device, 11...logarithmic amplifier 12...pulse amplifier
13...Pulse Wave Height Analyzer Patent Applicant Chest Co., Ltd. Representative Patent Attorney Takashi Kanakura Niyaku 20 Grain n, f Noa m no Yo 3= Pahi::・:□゛Sampling Height 1.1゜Pulse Wave Height (C) Pulse height (b) Pulse height: 1 11゜1,:゛

Claims (1)

[Claims] A laser beam is focused via a lens on a group of microparticles floating in a fluid in a flow channel pipe from a direction substantially perpendicular to the direction of movement, and the microparticles passing through this converging section and its vicinity. Among the scattered light of the laser beam, only the scattered light in a certain oblique direction with respect to the laser beam is focused by a condensing lens to form an image of the microparticle, and an iris is provided on this image plane to form an image of the microparticle. Only the scattered light of the microparticles passing through the condenser is passed through, and this scattered light is detected by a photodetector.The detected electrical signal is further amplified by a pulse amplifier, and then sequentially pulsed by a pulse height analyzer. A method for measuring particle size distribution of microparticles, characterized in that the particle size distribution of microparticles passing through the light collecting section is measured in real time by analyzing each wave height.