WO2018190162A1 - Particle measuring device and particle measuring method - Google Patents

Abstract

The objective of the present invention is to provide a particle measuring device and a particle measuring method which measure a particle size accurately. A flow cell (1) includes a flow passage (1a) for a sample fluid. An illuminating optical system (3) illuminates the sample fluid in the flow passage (1a) with light from a light source (2). An image capturing unit (4) captures an image of scattered light from a particle in a detection region in the flow passage (1a) through which the light passes, said image being captured in the direction in which the flow passage (1a) extends. On the basis of a plurality of still images of the particle captured by the image capturing unit (4) using a prescribed frame rate, a particle size identifying unit identifies an amount of movement of the particle in a two-dimensional direction as a result of Brownian motion, and determines the particle size of the particle from the amount of movement in the two-dimensional direction.

Description

Particle measuring apparatus and particle measuring method

The present disclosure relates to a particle measuring apparatus and a particle measuring method.

A particle counter using a light scattering phenomenon is widely known. However, the light scattering phenomenon depends on the relative refractive index between the solvent and the solute (particle). Therefore, for example, using a particle counter calibrated with polystyrene latex particles (PSL particles, refractive index: 1.59) in water (refractive index: 1.33), gold colloidal particles (refracted) having a particle size of 30 nm in water. When the rate is 0.467-i2.41 (when the light source wavelength is 532 nm), the particle size is estimated to be about 75 nm.

On the other hand, a particle measurement method has been proposed in which the particle diameter is obtained from the measured movement amount by paying attention to the movement amount (displacement amount) of the particle by Brownian motion obtained from the Stokes-Einstein equation. In this measurement method, the sample fluid is imaged at predetermined time intervals by the imaging unit from a direction perpendicular to the flow direction of the sample fluid using a linear flow cell. And the captured image is analyzed and the particle size is calculated | required based on the movement amount of the particle | grains by the Brownian motion of particle | grains (for example, refer patent document 1).

International Publication No. 2016/159131

In the above particle measurement method, the sample fluid is photographed from a direction substantially perpendicular to the flow direction of the sample fluid. For this reason, the captured image includes the amount of movement due to the flow rate of the sample fluid in addition to the amount of movement due to the Brownian motion. Therefore, in order to specify the amount of movement of particles due to Brownian motion, the amount of movement due to the flow rate of the sample fluid must be subtracted from the amount of movement of particles in the flow direction of the sample fluid. However, it is not easy to accurately know the accurate flow velocity distribution in the flow cell. Therefore, an error is likely to occur in the amount of movement of the particles due to the Brownian motion, and hence in the measured value of the particle size.

The particle measuring apparatus and particle measuring method of the present disclosure have been completed in view of the above problems. That is, an object of the present disclosure is to obtain a particle measuring apparatus and a particle measuring method that accurately measure the particle diameter and the number concentration for each particle diameter.

A particle measuring apparatus according to the present disclosure includes a flow cell that forms a flow path of a sample fluid containing particles, a light source that outputs light, an irradiation optical system that irradiates the sample fluid in the flow path with light from the light source, and light. A first imaging unit that captures scattered light from particles in a detection region in the flow path through which the image passes, and a plurality of still images of particles captured at a predetermined frame rate by the first imaging unit And a particle size specifying unit that specifies the amount of movement of the particle in the two-dimensional direction by Brownian motion and specifies the particle size of the particle from the amount of movement in the two-dimensional direction.

In the particle measurement method according to the present disclosure, a sample fluid in a flow path formed by a flow cell is irradiated with light from a light source, and scattered light from particles in a detection region in the flow path through which light passes is The amount of movement of the particle in the two-dimensional direction due to Brownian motion based on a plurality of still images of the particle imaged at a predetermined frame rate, and the particle from the amount of movement in the two-dimensional direction Identifying the particle size of the.

According to the present disclosure, it is possible to obtain a particle measuring apparatus and a particle measuring method that accurately measure the particle diameter.

FIG. 1 is a perspective view showing an optical configuration of the particle measuring apparatus according to the first embodiment of the present disclosure. FIG. 2 is a side view of the particle measuring apparatus shown in FIG. FIG. 3 is a block diagram showing an electrical configuration of the particle measuring apparatus according to the first embodiment of the present disclosure. FIG. 4 is a diagram for explaining the Brownian motion of particles in the XZ plane observed by the imaging unit 4 in the first embodiment. FIG. 5 is a perspective view showing an optical configuration of the particle measuring apparatus according to the second embodiment of the present disclosure. FIG. 6 is a block diagram showing an electrical configuration of the particle measuring apparatus according to the second embodiment of the present disclosure. FIG. 7 is a diagram for explaining the Brownian motion of particles in the XY plane observed by the imaging unit 61 in the second embodiment. FIG. 8 is a perspective view for explaining the configuration of the flow path of the particle measuring apparatus according to the third embodiment. FIG. 9 is a diagram for explaining the flow velocity distribution in the two-dimensional direction used in the third embodiment.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

Embodiment 1 FIG.

FIG. 1 is a perspective view showing an optical configuration of the particle measuring apparatus according to Embodiment 1 of the present disclosure. FIG. 2 is a side view of the particle measuring apparatus shown in FIG.

In FIG. 1, the flow cell 1 is bent in an L shape. The flow cell 1 includes a first channel 1a (Y direction in FIG. 1) and a second channel 1b (Z direction in FIG. 1) through which a sample fluid flows in a straight line. The shape of the cross section of the first flow path 1a (the cross section parallel to the XZ plane) is, for example, a rectangle of about 1 mm × 1 mm. The cross section of the second flow path 1b (cross section parallel to the XY plane) is also, for example, rectangular. For example, the flow cell 1 is made of synthetic quartz or sapphire. The flow cell 1 may have a crank shape or a U-shape as long as it has an L-shaped bent portion.

The light source 2 is a light source that emits irradiation light such as laser light. The irradiation optical system 3 emits the sample fluid from the light source 2 from a direction (X direction in FIG. 1) perpendicular to the traveling direction of the sample fluid (Y direction in FIG. 1) in the first flow path 1a, and Irradiation is performed with laser light shaped into a predetermined shape.

The imaging unit 4 (first imaging unit) includes an image sensor such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor) sensor. Using the image sensor, based on the scattered light from the particles in the detection region in the first flow path 1a through which the laser light passes, the particles are aligned in the direction of fluid flow in the extending direction of the first flow path 1a. The image is picked up by the image pickup unit 4 from the corresponding position. In Embodiment 1 of the present disclosure, the flow cell 1 has an L shape so that the direction of the flow of the sample fluid is changed from the first flow path 1a (Y direction) to the second flow path 1b (Z direction). It is bent. However, the flow direction of the sample fluid is not limited to this. For example, the flow of the sample fluid may be changed from the second channel (Z direction) to the first (Y direction). In this case, the imaging unit 4 captures an image from a position opposite to the flow direction in the detection region of the first flow path 1a.

The condensing optical system 5 condenses the scattered light from the particles in the detection region in the first flow path 1 a through which the laser light passes, on the image sensor of the imaging unit 4. The condensing optical system 5 is composed of, for example, a spherical lens or an aspheric lens. The condensing optical system 5 has an optical axis in the extension direction (Y direction in FIG. 1) of the fluid flow in the detection region of the first flow path 1a. The optical axis passes through the center of the detection region and the center of the image sensor of the imaging unit. That is, the “detection region” is a region where the laser beam and the range where the light is condensed on the image sensor by the condensing optical system 5 intersect. Here, as the detection region, the depth of field of the imaging unit 4 and the condensing optical system 5 is preferably larger than the width of the laser beam in the optical axis direction described above.

As shown in FIG. 2, a spherical concave portion 1c (concave lens shape) is formed on the inner wall of the flow cell 1 located between the above-described detection region and the condensing optical system 5. In this way, the distance from the detection region to the spherical surface (recess 1c) can be made substantially the radius of curvature of the spherical surface. As a result, it is possible to suppress refraction of scattered light that enters the inner wall of the flow cell 1 from the detection region. Furthermore, the measurement accuracy of the movement amount in the XZ plane can be easily improved. In addition, you may correct | amend by arithmetic processing instead of providing the recessed part 1c.

FIG. 3 is a block diagram showing an electrical configuration of the particle measuring apparatus according to the first embodiment of the present disclosure. In FIG. 3, the signal processing unit 11 acquires a captured image from the imaging unit 4. Based on the captured image, the signal processing unit 11 calculates the particle size of the particles, the number concentration for each particle size, the refractive index of the particles, and the like.

The signal processing unit 11 includes an image acquisition unit 21, a particle movement amount specifying unit 22, and a particle size specifying unit 23.

The image acquisition unit 21 has been captured by the imaging unit 4 at a predetermined frame rate (the number of still images constituting a moving image per unit time, for example, unit fps: frames per second), for example, 30 (fps). A plurality of frames (still images) are acquired from the imaging unit 4.

The particle movement amount specifying unit 22 specifies particles in each frame. Furthermore, the particle movement amount specifying unit 22 associates the same particles in each frame and specifies the movement amount. Further, when the particle movement amount specifying unit 22 specifies a particle, it sends image information to the scattered light intensity specifying unit 31.

The particle movement amount specifying unit 22 searches for particles within a predetermined range from the base point in the current frame, for example, using the position of the particle in the frame (still image) one frame before as the base point. Particles found within the predetermined range are identified as the same particles as the previous particle. Thereby, the trajectory of the particle is specified in a plurality of frames. As a result, the movement amounts x and z in the two-dimensional direction due to Brownian motion are specified.

The sample fluid flows in a laminar flow state along the Y direction in the vicinity of the detection region in the first flow path 1a. Therefore, there is almost no amount of movement due to the flow rate of the sample fluid in the XZ plane. Therefore, the particle movement amount specifying unit 22 can observe the Brownian motion without correcting the particle movement amount depending on the flow velocity of the sample fluid.

The particle size specifying unit 23 specifies the particle size d of each particle from the frame rate and the above-described movement amounts x and z in the two-dimensional direction.

For example, the particle size identification unit 23 identifies the diffusion coefficient D according to the following formula. Here, t is a time interval defined by the frame rate.

D = <x ² + z ² > / (4 · t)

Here, <a> represents the average of a.

That is, the particle size specifying unit 23 moves the particles in the X direction and the Z direction between two consecutive frames based on the position of the particles in N frames (still images) in time order constituting the imaging. The actual movement amount corresponding to is specified. In this way, the average of the sum of the square of the movement amount x in the X direction and the square of the movement amount z in the Z direction is calculated as <x ² + z ² >. Is done.

Then, the particle size identification unit 23 identifies the particle size d according to the following equation (Stokes-Einstein equation).

D = kB · T / (3π · η · D)

Where kB is the Boltzmann constant, T is the absolute temperature, and η is the viscosity coefficient of the sample fluid.

FIG. 4 is a diagram for explaining the Brownian motion of particles in the XZ plane observed by the imaging unit 4 in the first embodiment. Here, a case where three particles are imaged in the detection region is illustrated. FIG. 4 is a diagram showing the trajectory of the amount of movement due to Brownian motion obtained by connecting the positions of the particles specified in each frame with straight lines. The length of each straight line represents the amount of movement for each frame. As described above, when the Brownian motion of particles in the XZ plane is observed, it is not necessary to correct the amount of particle movement depending on the flow velocity of the sample fluid.

Furthermore, the signal processing unit 11 includes a scattered light intensity specifying unit 31 that specifies a representative luminance value of the track of each tracked particle by the scattered light.

The scattered light intensity specifying unit 31 acquires image information sent when the particle movement amount specifying unit 22 specifies a particle. By using an appropriate method such as binarizing area correction of the average luminance value obtained at each measurement point or the maximum luminance value of the same particle in the trajectory described above, the value corresponding to the scattered light intensity of the particle can be obtained. It is specified by the scattered light intensity specifying unit 31.

The analysis unit 35 calculates the number concentration for each particle size based on the particle size specified by the particle size specifying unit 23. Further, the analysis unit 35, for each particle, based on the particle size based on the diffusion coefficient specified by the particle size specifying unit 23 and the scattered light intensity equivalent value specified by the scattered light intensity specifying unit 31 Analyze the characteristics of the particles. For example, particles that have a known particle size and can be regarded as a substantially single particle size can be used as sample particles. Such particles include, for example, polystyrene latex particles. Using such particles as sample particles, the relationship between the known particle size and the relative scattered light intensity with respect to the known refractive index may be obtained in advance. By doing in this way, the refractive index of particle | grains can be specified or particle | grains and air bubbles can be distinguished. The results are output to a storage unit, a display unit, or an external output device (not shown).

Next, the operation of the particle measuring apparatus according to Embodiment 1 will be described.

When the particle measuring device starts operation, the light source 2 is turned on. The irradiation optical system 3 irradiates the sample fluid in the first flow path 1 a formed by the flow cell 1 with the laser light from the light source 2. The imaging unit 4 images particles based on scattered light from the particles in the detection region in the first flow path 1a through which the laser light passes. At this time, the scattering that has passed through the bent portion forming the spherical concave portion 1c (concave lens) of the flow cell 1 from the position facing the extending direction (Y direction in FIG. 1) of the fluid flow in the first flow path 1a. Light is imaged by the imaging unit 4 via the condensing optical system 5.

The signal processing unit 11 acquires a captured image from the imaging unit 4. Based on a plurality of frames (still images) of particles imaged at a predetermined frame rate (fps), as described above, the movement amounts x and z of the particles in the two-dimensional direction due to the Brownian motion are expressed as signal processing units. 11 is specified. Further, the signal processing unit 11 specifies the particle size of the particle and a representative scattered light intensity equivalent value from the frame rate (fps) and the movement amounts x and z in the two-dimensional direction. In this way, for example, the number concentration for each particle diameter or the refractive index of the particles can be measured.

As described above, according to the first embodiment, the flow cell 1 includes the flow path 1a for the sample fluid. The irradiation optical system 3 irradiates the sample fluid in the flow path 1 a with light from the light source 2. The imaging part 4 images the scattered light from the particle | grains in the detection area | region in the flow path 1a through which the above-mentioned light passes from the extension direction of the flow path 1a. The particle size identification unit 23 identifies the amount of movement of the particles in the two-dimensional direction due to Brownian motion based on a plurality of still images of the particles imaged at a predetermined frame rate by the imaging unit 4. The particle size specifying unit 23 specifies the particle size of the particles from the specified movement amount in the two-dimensional direction.

This makes it possible to accurately measure the particle size of the particles in the sample fluid.

That is, the sample fluid flows in a laminar flow state along the Y direction in the vicinity of the detection region of the first flow path 1a. As a result, particles are imaged from the extending direction of the first flow path 1a. Therefore, almost no amount of movement due to the flow velocity of the sample fluid is observed on the XZ plane. Therefore, it is not necessary to correct the amount of particle movement depending on the flow rate of the sample fluid. As a result, the amount of movement of particles is measured with high accuracy, and consequently the particle size is measured with high accuracy.

In the preceding case, the particle motion is imaged from the direction perpendicular to the flow direction of the sample fluid. The effective depth in the optical axis direction of the imaging system depends on the depth of field of the light receiving system. As a result, it is difficult to determine the particle detection region. In the present disclosure, the depth of field of the imaging system does not affect the determination of the particle detection area. This facilitates the determination of the particle detection area. As a result, the particle diameter and the number concentration can be measured with high accuracy.

Embodiment 2. FIG.

FIG. 5 is a perspective view showing an optical configuration of the particle measuring apparatus according to the second embodiment of the present disclosure. FIG. 6 is a block diagram showing an electrical configuration of the particle measuring apparatus according to the second embodiment of the present disclosure.

As shown in FIGS. 5 and 6, the particle measuring apparatus according to the second embodiment includes an imaging unit 61 (second imaging unit), a condensing optical system 62, an image acquisition unit 71, and a particle movement amount specifying unit 72. In addition.

The imaging unit 61 includes an image sensor such as a CCD or a CMOS. And the imaging part 61 uses the image sensor, based on the scattered light from the particle | grains in the above-mentioned detection area, makes a particle flow direction (Y in FIG. 5) of the fluid in the detection area | region of the 1st flow path 1a. The image is taken from a direction perpendicular to (direction) (Z direction in FIG. 5).

The imaging unit 4 and the imaging unit 61 desirably have the same frame rate (for example, 30 frames / second), and can switch frames in synchronization with each other. However, the aspects of the imaging unit 4 and the imaging unit 61 are not limited to this. For example, any imaging unit 4 and imaging unit 61 can be used as long as the imaging time can be matched for each frame (still image).

The image acquisition unit 71 acquires a plurality of frames imaged by the imaging unit 61 from the imaging unit 61.

The particle movement amount specifying unit 72 detects particles in the detection region in each frame acquired by the image acquisition unit 71. Then, the particle movement amount specifying unit 72 specifies the position of the particle in the two-dimensional direction (XY plane) in each frame. In this way, the particle movement amount specifying unit 72 specifies each movement amount x, y.

In the second embodiment, the particle size specifying unit 23 is specified by the movement amounts x and z in the two-dimensional direction (XZ plane) specified by the particle movement amount specifying unit 22 and the particle movement amount specifying unit 72. Based on the respective movement amounts x, y in the two-dimensional direction (XY plane) and the movement amounts x, y, z in the three-dimensional direction of the particles due to Brownian motion, the particle diameter d of the particles is determined. Identify.

For example, the particle size identification unit 23 identifies the diffusion coefficient D according to the following formula. Here, t is a time interval defined by the frame rate.

D = <x ² + y ² + z ² > / (6 · t)

That is, the particle size identification unit 23 moves the particles in the x direction, the y direction, and the z direction between two consecutive captured images based on the positions of the particles in the N captured images in the order of photographing time ( The actual distance), and (N−1) pieces of the X-direction movement amount x squared, the Y-direction movement amount y squared, and the Z-direction movement amount z squared. The average of the sum is calculated as <x ² + y ² + z ² >.

Then, the particle size identification unit 23 identifies the particle size d according to the above-described Stokes-Einstein equation.

Note that, for example, a plurality of particles may be detected in a frame captured by the imaging unit 4 and the imaging unit 61. In this case, the particle size identification unit 23 has a common direction (here, the plane (XZ plane) imaged by the imaging unit 4 and the plane imaged by the imaging unit 61 (XY plane)). An image of particles having the same amount of movement in the (X direction) is specified as an image of particles obtained by imaging one particle.

At this time, as in the first embodiment, the particle size identification unit 23 treats the movement amount in the X direction obtained from the frame (still image) of the imaging unit 4 as it is as the movement amount in the X direction by Brownian motion, and performs imaging. The amount of movement in the Z direction obtained from the frame of the unit 4 is handled as it is as the amount of movement in the Z direction due to Brownian motion. On the other hand, the particle size identification unit 23 subtracts the movement amount due to the flow velocity of the sample fluid from the movement amount in the Y direction obtained from the captured image of the imaging unit 61 to identify the movement amount in the Y direction due to Brownian motion.

FIG. 7 is a diagram for explaining the Brownian motion of particles in the XY plane observed by the imaging unit 61 in the second embodiment. FIG. 7A shows a trajectory of the amount of particle movement in a predetermined number of frames. FIG. 7B shows the flow velocity distribution in the Y direction of the sample fluid. FIG. 7C shows a trajectory of the amount of movement due to the Brownian motion of particles in a predetermined number of frames.

The flow velocity distribution of the sample fluid can be specified, for example, by fitting a flow velocity model (simulation) or by measuring in advance through experiments. The flow velocity distribution in the Y direction of the sample fluid in the detection region of the first flow path 1a is expressed as shown in FIG. 7B, for example. The amount of movement of the sample fluid is greatest at the center of the detection region and decreases as the distance from the center increases. Based on this flow velocity distribution and the position of the particles in the X direction, the amount of movement due to the flow velocity of the sample fluid in the Y direction is specified. For example, by subtracting the amount of movement due to the flow velocity of the sample fluid from the amount of movement of the particles in the Y direction obtained from the captured image, each amount of movement x, y in the two-dimensional direction due to the Brownian motion of the particles in the XY plane. Is identified.

Next, the operation of the particle measuring apparatus according to the second embodiment will be described.

When the particle measuring device starts operation, the light source 2 is turned on. The irradiation optical system 3 irradiates the sample fluid in the first flow path 1 a included in the flow cell 1 with the laser light from the light source 2. Based on the scattered light from the particles in the detection region in the first flow path 1a through which the laser light passes, the imaging unit 4 corrects the particles in the fluid flow direction (Y direction in FIG. 1) of the first flow path 1a. An image is taken from the opposite position. At the same time, the imaging unit 61 images the particles from a direction (Z direction in FIG. 1) perpendicular to the fluid flow direction of the flow path 1a based on the scattered light from the particles in the detection region. At this time, the imaging unit 4 and the imaging unit 61 capture images at a constant frame rate (fps) by synchronizing the frames with each other.

Then, the signal processing unit 11 acquires a captured image from the imaging units 4 and 61. Then, based on a plurality of frames (still images) of particles imaged at a predetermined frame rate (fps), as described above, each movement amount x, y, z of the particles in the three-dimensional direction due to Brownian motion is a signal. It is specified by the processing unit 11. In this way, the particle size of the particles can be specified from the movement amounts x, y, z in the three-dimensional direction.

Note that other configurations and operations of the particle measuring apparatus according to the second embodiment are the same as those in the first embodiment. Therefore, the description is omitted.

As described above, according to the second embodiment, the imaging unit 61 causes the particles of the first flow path 1a to be dispersed based on the scattered light from the particles in the detection region in the first flow path 1a through which light passes. An image is taken from a direction perpendicular to the fluid flow direction. The particle size specifying unit 23 performs Brownian motion based on a plurality of frames of particles captured at a predetermined frame rate by the imaging unit 4 and a plurality of frames of particles captured by the imaging unit 61 at a predetermined frame rate. The amount of movement of the particles in the three-dimensional direction is specified. Then, from the amount of movement in the above-described three-dimensional direction and a typical equivalent value of scattered light intensity, for example, the particle size of the particles, the number concentration for each particle size, or the refractive index of the particles is determined by the particle size specifying unit 23. Identified.

Thus, the three-dimensional movement amount corresponds to the movement amount of the true particle. Therefore, the particle diameter of the particles in the sample fluid can be measured with higher accuracy.

Embodiment 3 FIG.

FIG. 8 is a perspective view illustrating the configuration of the flow path of the particle measuring apparatus according to the third embodiment. FIG. 9 is a diagram illustrating the flow velocity distribution in the two-dimensional direction used in the third embodiment.

In Embodiment 3, the flow velocity distribution was evaluated by fluid simulation that directly calculates the Naviestokes equation. The purpose is to verify whether the influence of the flow rate of the sample fluid should be taken into account in detecting the amount of movement of the particles flowing in the flow cell bent in the L shape due to Brownian motion. This fluid simulation was performed using an existing method.

In this fluid simulation, the flow velocity distribution in the flow path having an L-shaped shape as shown in FIG. 8 was calculated. Simulation of the flow velocity distribution on the inflow path side in the vicinity of the coupling portion between the first flow path 81 as the inflow path (Y direction) serving as the bent portion of the flow path and the second flow path 82 as the outflow path (Z direction). Was conducted under the following conditions. That is, the cross section of the first flow path 81 is a square of 1 mm × 1 mm. And the cross section of the 2nd flow path 82 is a rectangle of 2.6 mm x 0.8 mm.

In this simulation, the sample fluid is an incompressible fluid (water) having a density of 1 g / mL and a viscosity of 1 mPa · s. Furthermore, the flow rate of this sample fluid is 0.3 mL / min. In this case, the average flow velocity in the first flow path 81 is 5.0 mm / s.

FIG. 9 shows that 0.25 mm, 0.5 mm, and 0.5 mm, respectively, from the bent position (Y = 0 in FIG. 8) of the joint portion of the first flow path 81 and the second flow path 82 to the first flow path 81 side. The cross section of the first flow path 81 at a position separated by 0.75 mm (in FIG. 8, Y = −0.25 mm, −0.5 mm, −0.75 mm) (perpendicular to the axial direction of the first flow path 81) A two-dimensional flow velocity vector in the cross section) is shown. 9A shows the case of 0.25 mm, FIG. 9B shows the case of 0.5 mm, and FIG. 9C shows the case of 0.75 mm. The two-dimensional flow velocity vector in the cross section represents the maximum value of the flow velocity in the plane, that is, the magnitude normalized by the in-plane average flow velocity of 5.0 mm / s. In any of the results, a flow velocity component in the bending direction (Z direction) perpendicular to the first flow path 81 appeared near the center of the first flow path 81. Further, it was found that the flow velocity component perpendicular to the first flow path 81 attenuates as the distance from the bent portion of the first flow path 81 decreases, that is, a flow along the first flow path 81 is formed. From the result of this simulation, the flow velocity component in the bending direction in the flow velocity is an average at a position that is 1 mm or more which is the width of the first flow path 81 (the width in the X direction or the width in the Z direction in FIG. It was found to reduce to less than 1% of the flow rate.

Therefore, in the process of observing the Brownian motion of the particles in the vicinity of the bent portion of the L-shaped channel having a shape as shown in FIG. 8 from the inflow channel direction (Y direction) and specifying the particle size of the particles from the Brownian motion, It is preferable to correct in consideration of the flow velocity component in the bending direction perpendicular to the first flow path 81 (Z direction in FIG. 9).

In the third embodiment, based on the above-described knowledge, when the detection region is within a predetermined range from the bending position of the flow path (a range where the distance from the bending position is less than 1 mm as described above), The position of the detection region in the first channel 81 (that is, along the first channel 81 in FIG. 8) by the above-described fluid simulation based on the channel shape of the particle measuring device and the fluid characteristics of the sample fluid. The flow velocity component of the sample fluid in the two-dimensional direction (X direction and Z direction) in the cross section (XZ plane in FIG. 8) at the position in the Y direction is specified.

And in Embodiment 3, the imaging part 83 similar to the above-mentioned imaging part 4 images the scattered light from the particle | grains in the detection area from the position facing the fluid flow direction in the detection area. The particle size identification unit 23 then includes a plurality of still images of particles imaged at a predetermined frame rate by the imaging unit 83, and the flow velocity component of the sample fluid in the two-dimensional direction in the detection region previously identified by the fluid simulation. Based on the above, the amount of movement of the particle in the two-dimensional direction by Brownian motion is specified. In this way, the particle size of the particles can be specified from the corrected two-dimensional movement amount.

Specifically, the particle size identification unit 23 determines the X direction and the Z direction of the particles between two consecutive frames based on the position of the particles in N frames (still images) in time order constituting the imaging. The actual amount of movement corresponding to the amount of movement is specified. Then, by subtracting the movement amount due to the flow velocity component of the sample fluid in the two-dimensional direction specified in advance by the fluid simulation from the actual movement amount, the movement amount in the two-dimensional direction of the particles due to the Brownian motion becomes the particle size. It is specified by the specifying unit 23. In the same manner as in the first embodiment, the particle diameter is specified from the movement amount of the particles in the two-dimensional direction due to Brownian motion.

Note that other configurations and operations of the particle measuring apparatus according to the third embodiment are the same as those in the first or second embodiment. Therefore, the description is omitted.

As described above, according to the third embodiment, even when the detection region is in the vicinity of the bent portion of the flow path, the movement amount of the particle in the two-dimensional direction due to the Brownian motion is accurately specified, and as a result The particle size is specified.

Note that various changes and modifications to the above-described embodiment will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the present embodiment and without diminishing the intended advantages. That is, such changes and modifications are intended to be included in the technical scope of the present embodiment.

For example, in the first, second, and third embodiments, the analysis unit 35 may calculate the number concentration by counting the number of particles having the particle size for each particle size specified by the particle size specifying unit 23. Good. In this case, the particle size identification unit 23 can further calculate the particle size distribution of the number concentration for each arbitrary particle size interval.

The particle measuring apparatus and the particle measuring method of the present disclosure can be applied to, for example, the measurement of the particle diameter of the particles contained in the sample fluid or the number concentration for each particle diameter.

DESCRIPTION OF SYMBOLS 1a 1st flow path 1b 2nd flow path 2 Light source 3 Irradiation optical system 4 Imaging part (an example of 1st imaging part)
22 particle movement amount specifying unit 23 particle size specifying unit 31 scattered light intensity specifying unit 35 analyzing unit 61 imaging unit (an example of a second imaging unit)

Claims (9)

A flow cell including a flow path for a sample fluid containing particles;
A light source that outputs light;
An irradiation optical system for irradiating the sample fluid in the flow path with the light from the light source;
A first imaging unit that images the scattered light from the particles in the detection region in the flow path through which the light passes, from an extension direction of the flow path;
Based on a plurality of still images of the particles imaged at a predetermined frame rate by the first imaging unit, the amount of movement of the particles in a two-dimensional direction due to Brownian motion is specified, and the amount of movement in the two-dimensional direction From the particle size specifying part for specifying the particle size of the particles,
A particle measuring apparatus. A second imaging unit that images scattered light from particles in a detection region in the flow path through which the light passes from a direction perpendicular to an extension direction of the flow path;
The particle size specifying unit includes a plurality of still images of the particles captured at a predetermined frame rate by the first imaging unit, and a plurality of the particles captured at the predetermined frame rate by the second imaging unit. The particle measuring apparatus according to claim 1, wherein a moving amount of the particle in a three-dimensional direction due to Brownian motion is specified based on the still image of the particle, and a particle size of the particle is specified from the moving amount in the three-dimensional direction. The first imaging unit and the second imaging unit have the same frame rate, and switch frames in synchronization with each other.
The particle size specifying unit specifies a still image captured by the first image capturing unit and a still image captured by the second image capturing unit for the same particle, and determines the particle by Brownian motion. The particle measuring apparatus according to claim 2, wherein a movement amount in a three-dimensional direction is specified, and further, a particle diameter of the particle is specified from the movement amount in the three-dimensional direction. From the image of the particle, a scattered light intensity specifying unit for specifying a value corresponding to the scattered light intensity of the particle,
An analysis unit that analyzes characteristics of the particles based on the particle size specified by the particle size specifying unit and the scattered light intensity equivalent value specified by the scattered light intensity specifying unit; Item 1. The particle measuring apparatus according to Item 1. The flow cell has a shape bent into an L shape,
The particle measuring apparatus according to claim 1, wherein the first imaging unit captures an image from a position facing the fluid flow direction in the detection region. The flow cell has a spherical recess in a portion bent into an L shape,
The particle measuring apparatus according to claim 5, wherein the first imaging unit images scattered light from the particles in the detection region via the recess. For each particle size specified by the particle size specifying unit, the number concentration is calculated by counting the number of particles having the particle size, and the particle size distribution of the number concentration for any particle size interval is calculated. The particle measuring apparatus according to claim 1, further comprising a unit. A flow cell including a flow path for a sample fluid containing particles;
A light source that outputs light;
An irradiation optical system that irradiates the sample fluid in the flow path with the light from the light source, a first imaging unit, and a particle size identification unit; the first imaging unit passes the light; In the detection area within a predetermined range from the bending position of the flow path, the scattered light from the particles is imaged from a position facing the fluid flow direction in the detection area,
The particle size specifying unit is configured to perform a Brownian motion based on a plurality of still images of the particles imaged at a predetermined frame rate by the first imaging unit and a flow velocity component in a two-dimensional direction of the sample fluid in the detection region. The amount of movement of the particles in the two-dimensional direction is specified, the particle size of the particles is specified from the amount of movement in the two-dimensional direction, and when the particle size of the particles is specified, the two-dimensional direction by fluid motion A particle measuring device that corrects for the effects of particle movement. Irradiating the sample fluid in the flow path included in the flow cell with light from a light source;
Imaging scattered light from particles in a detection region in the flow path through which the light passes, from an extension direction of the flow path;
Based on a plurality of still images of the particles imaged at a predetermined frame rate, the amount of movement of the particles in the two-dimensional direction due to Brownian motion is specified, and the particle size of the particles is specified from the amount of movement in the two-dimensional direction And a particle measuring method.

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