JP2011002265A - Device and method for measuring particle size - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a particle size measuring device capable of calculating a particle size distribution with high accuracy even when a particle group adheres to a cell.
A cell for containing a sample, a power source 3 for applying a voltage, an electrode 2 for forming an electric field that changes spatially in the cell 1 by applying a voltage from the power source 3, and measuring light for the sample. By stopping the voltage applied to the electrode 2 from the power source 3 and the detector 151 for detecting the diffracted light intensity due to the diffracted light generated by irradiating the sample with the measurement light, the light source 4 to be irradiated is measured in the medium. Particle size measuring apparatus 10 comprising an applied voltage control unit 31 that causes diffusion in the measurement particle group, and a particle size calculation unit 35 that calculates the particle size distribution of the particle group to be measured based on the temporal change of the diffracted light intensity. In this case, the particle size calculation unit 35 calculates the diffracted light intensity when the set time has elapsed from the diffusion start time as a base of the diffracted light intensity obtained when the measured particle group is uniformly dispersed in the medium. Line.
[Selection] Figure 1

Description

  The present invention relates to a particle size measuring apparatus and a particle size measuring method for calculating a particle size distribution of a group of particles to be measured using an optical technique (for example, an induction diffraction grating method (IG method), etc.). Using a transient diffraction grating (hereinafter also referred to as “density diffraction grating”) based on the particle density distribution of the formed particle group to be measured, the diffusion coefficient of the particle group to be measured is calculated. The present invention relates to a particle size measuring apparatus and a particle size measuring method for calculating the distribution of the particle size.

  Measurement of particle size d of particles dispersed in a medium (eg, liquid such as water, gel, etc.) is a product whose particle size d such as pharmaceutical, chemical, abrasive, ceramics and pigments affects quality. Has been done about. Furthermore, particles having a particle diameter d of 100 nm or less are generally referred to as nanoparticles, and even if they are the same material, they exhibit properties different from ordinary bulk materials, and thus are beginning to be used in various fields.

As a measurement method for measuring the particle diameter d of the nanoparticles, the electric field distribution having a spatial periodic pattern is generated in a sample in which the particles are dispersed in a medium, thereby causing the particles to undergo dielectrophoretic action (or electrophoretic action). By moving with the above, a density diffraction grating in which a dense region and a sparse region of particle groups are periodically arranged in a medium is formed, and laser light (measurement light) is irradiated to the density diffraction grating, after detecting the diffracted light intensity I ₀ due to the density grating, by stopping to generate an electric field distribution, the time of the diffracted light intensity I _t by density diffraction grating go blurred by diffusing particles in a medium A method is disclosed in which the diffusion coefficient D of the particle group is calculated by measuring the change, and further the particle diameter d is calculated from the diffusion coefficient D (see, for example, Patent Document 1).

According to such a measuring method, since the diffusion coefficient D increases as the particle diameter d decreases, the fact that the formed density diffraction grating disappears earlier is utilized. Specifically, until when the density grating disappears that to generate an electric field distribution from the diffusion start time t ₀ of stopping, by continuing to detect the diffracted light intensity I _t by irradiating a laser beam to the sample , it measures the time change of the diffracted light intensity I _t.
FIG. 7A is a graph showing the relationship between the voltage value V and time t, and FIG. 7B is a graph showing the relationship between the diffracted light intensity I and time t. In FIG. 7 (a), by applying a voltage between the frequency _{f n} and the voltage value _{V n} and the applied time Delta] t _n. Then, the start time of the application time Delta] t _n is the dielectrophoretic effect start time t _s, end time becomes ₀ diffusion start time t of the application time Delta] t _n, detected spreading start time t ₀ diffracted light intensity I _t Becomes the diffracted light intensity I ₀ .

Then, in order to calculate the diffusion coefficient D from the time change of the diffracted light intensity I _t, and using the following equation (1).
I _t = I ₀ exp (−2Dq ² t) (1)
Here, q = 2π / Λ, t is time elapsed from the diffusion starting time t _0, I ₀ is the diffracted light intensity detected in the diffusion starting time t _0, I _t is the diffracted light intensity detected in the time t, Λ is the grating spacing of the density diffraction grating.
Next, after calculating the diffusion coefficient D, the particle diameter d is calculated from the diffusion coefficient D by inputting the absolute temperature T and the viscosity μ of the medium using the Einstein-Stokes relationship represented by the following formula (2). ing.
_{D = K B T / 3πμd ·····} (2)
Here, _{K B} is the Boltzmann constant.

FIG. 8 is a schematic block diagram showing the overall configuration of a particle size measuring apparatus using such a measuring method. FIG. 2 is a perspective view showing an example of a sample cuvette (cell).
The particle size measuring apparatus 100 includes a sample cuvette 1 in which a sample is accommodated, an AC power source 3 that applies an AC voltage to an electrode pair 2 provided in the sample cuvette 1, and a laser beam ( comprises a laser light source 4 for irradiating the measurement light), a detection optical system 150 for detecting the first-order diffracted light intensity I _t, an amplifier 6, and a control unit 70 for controlling the entire particle diameter measuring device 100 .

The sample cuvette 1 is made of glass having a rectangular bottom surface 12 and four side walls 11, and has light transmittance. A sample is accommodated in the sample cuvette 1.
An electrode pair 2 is formed on the surface (inner surface) of one side wall 11 of the sample cuvette 1. FIG. 3 is a plan view showing an example of the side wall 11 on which the electrode pair 2 is formed, and FIG. 4 is a cross-sectional view showing a part of the cross section of the sample cuvette.
The electrode pair 2 includes a left electrode 21 and a right electrode 22.
The left electrode 21 has a linear electrode piece 21a having a width L (for example, 1 μm) arranged in parallel with a space therebetween, and a linear electrode piece that electrically connects the outer side ends of the electrode pieces 21a. A connecting portion 21b is provided to form a so-called comb electrode.
The right electrode 22 is the same as the left electrode 21, and linear electrode pieces 22 having a width L (for example, 1 μm) are arranged in parallel with a space therebetween, and the outer ends of these electrode pieces 22a are connected to each other. A linear connection portion 22b for electrical connection is provided to form a so-called comb-shaped electrode.
And each space | interval of the electrode piece 21a and the electrode piece 22a is arrange | positioned at predetermined distance S (for example, 1 micrometer), respectively.
Further, the AC power source 3 is connected to the upper end portion of the connection portion 21b and the upper end portion of the connection portion 22b.

Thus, an electric field distribution is formed in the sample cuvette 1 by applying an AC voltage from the AC power source 3 to the electrode pair 2. Then, a group of particles aggregates due to dielectrophoresis between the electrode piece 21a and the electrode piece 22a where electric lines of force concentrate. On the other hand, no particle group exists due to dielectrophoresis between the electrode pieces 21a and 21a and between the electrode pieces 22a and 22a. Therefore, the region P in which the particle group is aggregated is formed so as to have a lattice interval Λ (see FIG. 4a). That is, the region P in which the particle group is aggregated has a higher particle density than the other regions and has a different refractive index, so that a density diffraction grating having a lattice interval Λ is formed.
Further, if an AC voltage from the AC power source 3 is not applied to the electrode pair 2, an electric field distribution is not formed in the sample cuvette 1, so there is no region where electric lines of force are concentrated, and particles are present uniformly in the medium. (See FIG. 4b). That is, the particle density is uniform and the refractive index is the same.

  Examples of the material of the electrode pair 2 include ITO, and the refractive index of ITO is about 2.0. As a material of the side wall 11 of the sample cuvette 1, a high refractive index glass (for example, a trade name “s -LAH79 "; manufactured by OHARA; refractive index 2.0) eliminates the refractive index difference between the electrode pair 2 and the side wall 11, thereby generating diffracted light by the electrode pair 2 during laser light irradiation. Can be suppressed.

As the AC power source 3, an AC power source capable of applying an AC voltage having a frequency f _n , a voltage value V _n and an application time Δt _n that can cause dielectrophoresis in the particle group is used. Specifically, an AC power source or the like that can be freely selected from a voltage value of 1 to 100 V and a frequency of about 10 kHz to 10 MHz and can apply the selected AC voltage is used.
The type of the laser light source 4 may be selected according to the particle group. For example, it is a He—Ne laser light source (wavelength λ = 0.6328 μm). Then, the sample cuvette 1 is irradiated with laser light.

Detecting optical system 150 includes a detector 151 for detecting the first-order diffracted light intensity _{I t,} circular diameter 1mm to avoid unnecessary noise light (area: 0.785 mm ²⁾ pins having a pin hole It comprises a hall plate 152 and an optical axis adjusting light receiving portion 153 for grasping the position of the optical axis L of the laser light source 4.
The detector 151 is composed of one photodiode (light receiving element). In front of the detector 151, a pinhole is arranged so as to detect only the diffracted light of the order m diffracted by the density diffraction grating by the particle group out of the laser light emitted from the laser light source 4.
Here, when the lattice spacing Λ of the density diffraction grating, the wavelength λ of the laser beam, the diffraction angle θ, and the order m, the following formula (3) is established.
mλ = Λ · sinθ (3)
Therefore, for example, when λ = 0.6328 μm and Λ = 3 μm, m = 1st-order diffracted light appears at θ≈12 °, so that light having an angle θ≈12 ° with respect to the optical axis L is pinned. A pinhole plate 152 is disposed so as to pass through the hole.

By the way, in the measurement method as described above, since the sample containing particles having the same particle diameter d is evaluated, the diffusion coefficient D is from the diffusion start time t ₀ to the time when the density diffraction grating disappears. Since it is constant, the particle diameter d can be calculated by calculating the diffusion coefficient D.
However, a sample including a particle group having a non-uniform particle diameter d (for example, a sample in which m kinds of particle groups having different particle diameters are mixed, a sample including a particle group having a varied particle diameter, or the like) is evaluated. In this case, since the particle groups having different diffusion coefficients D are mixed, the above-described measurement method cannot be simply applied.

Therefore, the applicant can calculate the distribution of the particle diameter d by measuring a sample (that is, a polydisperse system) including a particle group having a non-uniform particle diameter d using the measurement method as described above. An analysis method that can be used has been disclosed (for example, see Patent Document 2).
For example, the following equation (4) is used to express the disappearance process of the density diffraction grating with m kinds of particle diameters d, and by solving the abundance ratio of the m kinds of particle diameters d by a numerical analysis method such as the least square method. The distribution of the particle diameter d is calculated.

Here, m is the number of types of particle diameter d contained in the sample, φ _p is the electric field phase of the particle group having the p-th particle diameter d out of the m types of particle diameters d, and D _p is m types. The diffusion coefficient of the particle group of the p-th particle diameter d out of the particle diameter d, q = 2π / Λ, Λ is the lattice spacing of the density diffraction grating, N is the number of lattice periods of the density diffraction grating, and t is the diffusion start time t time elapsed from _0, I _t is the magnitude of the diffracted light intensity from baseline were detected time t.

JP 2006-84207 A International Publication WO2008 / 155854

Meanwhile, when calculating the distribution of the particle diameter d in the analysis method described above, the input initial values of the baseline or the like of the diffracted light intensity I _s obtained when the particles are uniformly dispersed in a medium There is a need to. Therefore, in the conventional analysis method, the diffracted light intensity I _t before the voltage is applied from the AC power source 3 to the electrode pair 2 is used as the diffracted light intensity I _t obtained when the particles are uniformly dispersed in the medium. Was the baseline.

  However, when the measurement is performed, the particle group is likely to aggregate between the electrode piece 21a and the electrode piece 22a by the dielectrophoresis. Particle groups sometimes adhered. And even if it stops applying a voltage to the electrode pair 2 from the AC power supply 3, the adhered particle group does not move freely in the medium as shown in FIG. 4c. Therefore, when the particle group adheres to the side wall 11, there is a problem that accuracy is lowered even if the distribution of the particle diameter d is calculated.

Further, in order to accurately calculate the distribution of the particle diameter d, the measurement may be repeated many times (for example, 10 times) while the sample cuvette 1 is placed. the diffracted light intensity I _s before application of a voltage to 2, when it is determined that baseline limit I _th or more, also the particle diameter measuring device for reporting on a display device or the like to clean the sample cuvette 1 Conceivable. Note that the distribution of the particle diameter d cannot be calculated with high accuracy if only a small amount of particles adhere to the sample cuvette 1 just by grasping that the amount of particles attached to the sample cuvette 1 has increased. .

In order to solve the above problems, the present inventors have studied a method that can calculate the distribution of the particle diameter d with high accuracy even when a particle group adheres to the cell. FIG. 5A is a graph showing the relationship between the voltage value V and the time t, and FIG. 5B shows the diffracted light intensity I obtained when the particle group adheres to the side wall 11 of the sample cuvette 1. It is a graph which shows the relationship with time t.
As shown in FIG. 5 (b), when the particles adhered to the side walls 11 of the sample cuvette 1, the diffracted light intensity I _t before application of a voltage from the AC power supply 3 to the electrode pair 2, the diffracted light intensity the diffracted light intensity I _t when I _s, and the sufficient time from the diffusion start time t ₀ of the first measurement has elapsed became diffracted light intensity I _b1. That is, the diffracted light intensity I _t when sufficient time has elapsed from the diffusion starting time t _0, since there remains a particle group attached to the side wall 11 of the sample cuvette 1, I did not become diffracted light intensity I _s.
Therefore, since the particle group attached to the side wall 11 of the sample cuvette 1 does not contribute to the diffusion coefficient D, in the first measurement, the diffracted light intensity I _b1 when the set time has elapsed from the diffusion start time t ₀ is obtained. , it found that the baseline of the diffracted light intensity I _t obtained when particles in a medium is uniformly dispersed.

  That is, the particle size measuring apparatus of the present invention includes a cell that contains a sample containing a group of particles to be measured in a medium, a power source that applies a voltage, and a spatial periodic change in the cell by applying a voltage from the power source. An electrode for forming an electric field, a light source for irradiating the sample with measurement light in a state in which electrophoretic migration is caused in the measured particle group in the medium by the electric field, and irradiating the sample with measurement light By detecting the intensity of the diffracted light generated by the diffracted light generated by the light source and stopping the voltage applied to the electrode from the power source, the measured particle group is diffused in the medium, thereby causing the diffracted light to Based on the applied voltage control unit that causes the change and the temporal change in the diffracted light intensity from the diffracted light intensity at the diffusion start time when the voltage is stopped, the particle size distribution of the measured particle group is calculated. Particle size calculator A particle size measuring apparatus comprising: a particle size calculation unit, wherein the measured particle group is uniformly dispersed in the medium with the diffracted light intensity when a set time has elapsed from the diffusion start time. The baseline of the diffracted light intensity obtained in (1) is used.

Here, as the “electrophoresis”, for example, an electrostatic migration in which a voltage is applied to a charged group of particles to be measured and the group of particles to be measured is electrophoresed, or a voltage is applied to a polarized group of particles to be measured. Examples thereof include dielectrophoresis in which a group of particles to be measured is electrophoresed by application.
The “measurement light” is preferably laser light, but is not limited to this, and light using an LED, light dispersed by a spectroscope, light having a wavelength range limited by an interference filter, a bandpass filter, or the like is used. Also good.
The “medium” is not limited as long as the particles to be measured can migrate inside, and examples thereof include liquids such as water and oil, gels, and solids.
Furthermore, as the “set time”, by stopping the voltage applied to the electrode from the power source, the measured particle group is diffused in the medium, except for the measured particle group attached to the cell or the electrode, It may be a time for the group of particles to be measured to be uniformly dispersed, and may be determined in advance by determining that a sufficiently long time has been determined in advance or that there is almost no change in the diffracted light intensity over time.

In the particle size measuring apparatus of the present invention, first, a sample containing a group of particles to be measured in a medium is accommodated in a cell. At this time, since the particles to be measured in the medium are uniformly dispersed, the diffracted light intensity I _t is a very weak diffracted light intensity I _s.
Next, by applying a voltage to the electrodes, an electric field that varies spatially with respect to the space in the cell is formed. Then, electrophoretic migration occurs in the group of particles to be measured, resulting in a spatial periodic concentration change in which dense regions and sparse regions are periodically arranged so as to correspond to the spatial period of the electric field. A density diffraction grating is formed by the measurement particle group. In this case, the density diffraction grating is formed stably, the diffracted light intensity I _t is a very strong diffracted light intensity I _0.
When the applied voltage control unit stops the voltage applied to the electrodes, the electric field that changes spatially disappears, so that the particle group to be measured gradually diffuses. That is, the density diffraction grating collapses and becomes blurred. In this case, to detect a temporal change in the diffracted light intensity I _t. As a result, the relationship between the time t from the diffusion start time t ₀ when the voltage is stopped and the diffracted light intensity I is obtained. The diffraction intensity I _t is adapted to attenuate with time.

Furthermore, the time setting the voltage applied to the electrodes from the stop has passed, the diffracted light intensity I _t is a weak diffraction intensity I _b1. At this time, if the adhered particles to be measured into the cell or the electrode, becomes diffracted light intensity I _s before application of a voltage to the electrodes from the power supply, while the particles to be measured in the cell or electrodes adhered lever, not to the diffracted light intensity _{I s.}
The particle diameter calculation unit, based on the temporal change of the diffracted light intensity I _t, but will calculate a particle size distribution d, in this embodiment, the diffracted light intensity before applying the voltage from the power source to the electrode the I _s, without baseline of the diffracted light intensity I _t, 1 time in measurement, diffracted light intensity I _b1 when the time set from the spreading start time t ₀ has elapsed, the baseline of the diffracted light intensity I _t And

  As described above, according to the particle size measuring apparatus of the present invention, the particle size distribution can be calculated with high accuracy even if the particle group adheres to the cell or the electrode.

(Means and effects for solving other problems)
Further, in the particle size measuring device of the present invention, based on the diffracted light intensity when a set time has elapsed from the diffusion start time and the diffracted light intensity before applying a voltage from the power source to the electrode, the cell Or you may make it provide the adhesion amount determination part which reports the washing | cleaning time which wash | cleans the said cell or an electrode by estimating the adhesion amount of the particle group to an electrode.
According to the particle size measuring apparatus of the present invention, in order to accurately calculate the distribution of the particle size d, particles that adhere to the cell or electrode when the measurement is repeated many times while the cell or electrode is placed. It is possible to grasp a change in the amount of the group, and as a result, it is possible to appropriately report the cleaning time for cleaning the cell or the electrode.

  Further, the particle size measuring method of the present invention includes a cell that contains a sample containing a group of particles to be measured in a medium, a power source that applies a voltage, and a spatial periodic change in the cell by applying a voltage from the power source. An electrode for forming an electric field, a light source for irradiating the sample with measurement light in a state in which electrophoretic migration is caused in the measured particle group in the medium by the electric field, and irradiating the sample with measurement light By detecting the intensity of the diffracted light generated by the diffracted light generated by the light source and stopping the voltage applied to the electrode from the power source, the measured particle group is diffused in the medium, thereby causing the diffracted light to Based on the applied voltage control unit that causes the change and the temporal change in the diffracted light intensity from the diffracted light intensity at the diffusion start time when the voltage is stopped, the particle size distribution of the measured particle group is calculated. Particle size calculator A particle size measuring method using a particle size measuring apparatus comprising: when the set of particles to be measured are uniformly dispersed in the medium, the diffracted light intensity when a set time has elapsed from the diffusion start time The method includes a baseline determination step as a baseline of the diffracted light intensity obtained.

1 is a schematic configuration block diagram showing an overall configuration of a particle size measuring apparatus according to an embodiment of the present invention. It is a perspective view which shows an example of a sample cuvette. It is a top view which shows an example of the side wall in which the electrode pair was formed. It is sectional drawing which shows a part of cross section of a sample cuvette. It is sectional drawing which shows a part of cross section of a sample cuvette. It is sectional drawing which shows a part of cross section of a sample cuvette. It is the graph which shows the relationship between a voltage value and time, and the graph which shows the relationship between the diffracted light intensity | strength obtained when a particle group adheres to the side wall of a sample cuvette, and time. It is a graph which shows the relationship between the frequency | count of a measurement, and diffracted light intensity. It is the graph which shows the relationship between a voltage value and time, and the graph which shows the relationship between diffracted light intensity and time. It is a schematic block diagram which shows the whole structure of the conventional particle diameter measuring apparatus.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments described below, and it goes without saying that various aspects are included without departing from the spirit of the present invention.

FIG. 1 is a schematic block diagram showing the overall configuration of a particle size measuring apparatus according to an embodiment of the present invention. FIG. 2 is a perspective view showing an example of a sample cuvette (cell). In addition, the same code | symbol is attached | subjected about the thing similar to the particle diameter measuring apparatus 100. FIG.
In this embodiment, the distribution of the particle diameter d of the measured particle group is calculated by measuring a sample in which the measured particle group is dispersed in a medium. A medium having a known viscosity μ is used. Then, it is assumed that a group of particles to be measured that are polarized by dielectrophoresis by applying an AC voltage is migrated in the medium.
The particle diameter measuring apparatus 10 includes a sample cuvette 1 in which a sample is accommodated, an AC power source 3 that applies an AC voltage to an electrode pair 2 provided in the sample cuvette 1, and laser light to the sample cuvette 1. comprises a laser light source 4 for irradiating a detection optical system 150 for detecting the first-order diffracted light intensity I _t, an amplifier 6, and a control unit 7 for controlling the overall particle size measurement device 10.

The control unit 7 includes a CPU 30 and a memory 40, and is connected to a display device (not shown) having a monitor screen and an input device (not shown) having a keyboard, a mouse, and the like.
Further, the light intensity capturing will be described with blocking functions CPU30 processes, the applied voltage control unit 31 for controlling the AC power source 3, a laser light source controller 32 for controlling the laser light source 4, the light intensity I _t The acquisition control unit 36 includes an adhesion amount determination unit 34 that reports a cleaning time for cleaning the sample cuvette 1, and a particle size calculation unit 35 that calculates a distribution of the particle size d.

The laser light source control unit 32 controls the laser light source 4 so that the sample cuvette 1 is irradiated (ON) with laser light or stopped (OFF).
Light intensity acquisition control unit 36 performs control to detect the first-order diffracted light intensity I _t detected by the detector 151.
The applied voltage control unit 31 controls the AC power supply 3 so as to apply an AC voltage to the electrode pair 2. Thereby, when the applied voltage control unit 31 applies an alternating voltage to the electrode pair 2, an electric field distribution is formed in the sample cuvette 1. On the other hand, if an alternating voltage is not applied to the electrode pair 2, An electric field distribution is not formed in the sample cuvette 1.

Particle diameter calculating unit 35 based on the time variation of the resulting diffracted light intensity I _t at the light intensity acquisition control unit 36 performs control for calculating the distribution of the particle diameter d of the particles to be measured in the medium.
For example, based on the time change and the expression of the diffracted light intensity _{I t (1) ~ (4} ), but will calculate a particle size distribution d, in this embodiment, AC from the AC power supply 3 to the electrode pair 2 the diffracted light intensity I _s before a voltage is applied, without the baseline of the diffracted light intensity I _t. Therefore, the first measurement, the diffracted light intensity I _b1 when the time set from the spreading start time t ₀ Delta] t _b has passed, the baseline of the diffracted light intensity I _t. Further, in the second measurement, the diffracted light intensity I _b2 of when the time set from the spreading start time t ₀ Delta] t _b has passed, the baseline of the diffracted light intensity I _t. Furthermore, in the third measurement, the diffracted light intensity I _b3 when the time set from the spreading start time t ₀ Delta] t _b has passed, the baseline of the diffracted light intensity I _t. That is, in the present embodiment, for each measurement, the diffracted light intensity I _b of when the time setting from the spreading start time t ₀ Delta] t _b has elapsed, then the baseline of the diffracted light intensity I _t, based the diffracted light intensity I _t The line will fluctuate.
At this time, setting time Delta] t _b in advance in the memory 40 for example, will have been stored as 5 minutes after such diffusion start time t _0.
Further, when it is determined that the diffracted light intensity I _b1 , the diffracted light intensity I _b2 or the diffracted light intensity I _b3 is equal to or higher than the baseline upper limit value I _th, it is reported to the display device or the like.

Adhesion amount determination unit 34, based on the time variation of the resulting diffracted light intensity I _t at the light intensity acquisition control unit 36 performs control to report cleaning time for cleaning the sample cuvette 1.
For example, the diffracted light intensity I _s before applying an AC voltage from the AC power source 3 to the electrode pair 2 and the diffracted light intensity I _b1 when a set time Δt _b elapses from the diffusion start time t ₀ of the first measurement. , a second diffracted light intensity I _b2 of when the time set from the spreading start time t ₀ Delta] t _b has passed the measurement, diffracted light when the set time Delta] t _b has elapsed from the diffusion start time t ₀ of the third measurement Based on the intensity I _b3 , a graph showing the relationship between the number of times of measurement N and the diffracted light intensity I is created as shown in FIG. 6, and the change in the amount of particles adhering to the sample cuvette 1 To figure out. And, the more the amount of group particles attached to the sample cuvette 1, and calculates the number n of measurements reaches the baseline limit I _th, which makes it impossible to accurately calculate the distribution of the particle diameter d, the sample cuvette 1 Is displayed on a display device or the like.

  As described above, according to the particle diameter measuring apparatus 10, the distribution of the particle diameter d can be calculated with high accuracy even when the measured particle group adheres to the sample cuvette 1. In addition, in order to accurately calculate the distribution of the particle diameter d, when the measurement is repeated many times while the sample cuvette 1 is placed, the state of change in the amount of particles attached to the sample cuvette 1 is grasped. As a result, the cleaning time for cleaning the sample cuvette 1 can be appropriately reported.

  The present invention uses a density diffraction grating formed of a measured particle group formed in a medium, calculates a diffusion coefficient of the measured particle group, and further calculates a particle size distribution from the diffusion coefficient, etc. Can be used for

1 Sample cuvette (cell)
2 Electrode Pair 3 AC Power Supply 4 Laser Light Source 10 Particle Size Measuring Device 31 Applied Voltage Control Unit 35 Particle Size Calculation Unit 151 Detector

Claims (3)

A cell containing a sample containing a group of particles to be measured in a medium;
A power supply for applying voltage;
An electrode that forms an electric field that varies spatially in the cell by applying a voltage from the power source;
A light source for irradiating the sample with measurement light in a state in which electrophoretic migration is caused in the particles to be measured in the medium by the electric field;
A detector for detecting the intensity of diffracted light caused by diffracted light generated by irradiating the sample with measurement light;
An applied voltage control unit that causes a change in the diffracted light by causing the particles to be measured to diffuse in the medium by stopping the voltage applied to the electrode from the power source;
Particle size measurement comprising: a particle size calculation unit for calculating a particle size distribution of the group of particles to be measured based on a temporal change in the diffracted light intensity from the diffracted light intensity at the diffusion start time when the voltage is stopped A device,
The particle size calculation unit has a diffracted light intensity when a set time has elapsed from the diffusion start time, and a baseline of the diffracted light intensity obtained when the particles to be measured are uniformly dispersed in the medium. A particle diameter measuring apparatus characterized by:   Based on the diffracted light intensity when a set time has elapsed from the diffusion start time and the diffracted light intensity before applying a voltage from the power source to the electrode, the amount of particles attached to the cell or electrode is predicted. The particle size measuring apparatus according to claim 1, further comprising an adhesion amount determination unit that reports a cleaning time for cleaning the cell or the electrode. A cell containing a sample containing a group of particles to be measured in a medium;
A power supply for applying voltage;
An electrode that forms an electric field that varies spatially in the cell by applying a voltage from the power source;
A light source for irradiating the sample with measurement light in a state in which electrophoretic migration is caused in the particles to be measured in the medium by the electric field;
A detector for detecting the intensity of diffracted light caused by diffracted light generated by irradiating the sample with measurement light;
An applied voltage control unit that causes a change in the diffracted light by causing the particles to be measured to diffuse in the medium by stopping the voltage applied to the electrode from the power source;
Particle size measurement comprising: a particle size calculation unit for calculating a particle size distribution of the group of particles to be measured based on a temporal change in the diffracted light intensity from the diffracted light intensity at the diffusion start time when the voltage is stopped A particle diameter measuring method using an apparatus,
Including a baseline determination step in which the diffracted light intensity when a set time has elapsed from the diffusion start time is used as a baseline of the diffracted light intensity obtained when the particles to be measured are uniformly dispersed in the medium. A particle diameter measuring method characterized by the above.