JP5643156B2 - Fluid measuring instrument and fluid measuring method - Google Patents

Description

  The present invention relates to a fluid measuring device, and more particularly to a fluid measuring device that can be applied as a measuring device for the flow rate and flow velocity of a microchannel, the number of particles in a fluid, the particle concentration, the particle diameter, and the like.

  The micro-integrated chemical analysis system, so-called μTAS (Micro Total Analysis Systems), is a micro-channel, reaction vessel, and detection vessel that form a flow channel for liquids that are reagents and samples. This is a system for mixing and reacting fluids in a microchannel based on the spontaneous behavior of fluids. Such a system is expected to make it possible to dispose of the chip, reduce the reagents and samples used, increase the analysis speed, automate the measurement, make the apparatus portable, and reduce the cost.

For example, in an analysis apparatus for livestock diagnosis using milk or the like as a sample, μTAS is very useful because it can be easily used in a barn and the chip used for the inspection can be disposable. (Non-patent documents 1, 2, 3, 4).
In such a system using μTAS, in order to monitor the state of the fluid flowing through the flow path, the flow rate, flow rate, particle behavior, and particle concentration are observed in the laboratory by photographing under a microscope and analyzing the moving image. doing. In addition, when the microscope cannot be used for some reason, the estimated value is used based on the measurement result in the laboratory.

T.Miura, et al., “Capillary-Driven Flow Chip for Simple and Quick SPR Measurement”, Pittcon Conference and Expo 2008, 360-5, 2008 Y. Iwasaki, et al., “Rapid Identification of Pathogens in Food Samples Using Simplified Immunoassay System”, Pittcon Conference and Expo 2008, 360-7, 2008 Gen Iwasaki et al., “Ubiquitous Biomolecular Sensor”, Monthly Bioindustry, December, p.24-29, 2009 “Surface plasmon chemical sensor”, NTT Microsystem Integration Laboratories, search on December 1, 2010, Internet, <http: // www. ntt. co. jp / milab / project / pr09_spr. html>

  In the method of analyzing the moving image by taking a picture with a microscope in order to observe the flow velocity and flow rate of the fluid, the behavior of the particle, and the particle concentration, there is a problem that it takes time to analyze the moving image and it takes a real time property. In addition, it is necessary to use a computer with high computing power for moving image analysis, and there is a problem that the cost becomes high. Moreover, in the situation where the microscope is not used, there is a problem that the measurement becomes inaccurate because it is necessary to rely on the estimated value.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a fluid measuring device and a fluid measuring method capable of measuring the moving speed of particles accurately and inexpensively in a short time.
It is another object of the present invention to provide a fluid measuring instrument and a fluid measuring method that can measure the flow rate of fluid accurately and inexpensively in a short time.
It is another object of the present invention to provide a fluid measuring device and a fluid measuring method capable of measuring the number of passing particles, the moving speed, and the traveling direction accurately and inexpensively in a short time.
Another object of the present invention is to provide a fluid measuring device and a fluid measuring method that can measure the radius of particles accurately and inexpensively in a short time.

The fluid measuring device of the present invention includes a flow channel covered with a transparent plate that scatters light, a laser light source that irradiates laser light to the fluid in the flow channel through the transparent plate, and a plurality of locations in the flow channel. A plurality of light receivers that receive the light scattered by the transparent plate and the light scattered by the particles contained in the fluid and convert them into electrical signals, and are included in the electrical signals obtained by the light receivers The power spectrum measuring means for measuring the power spectrum of the beat signal, the frequency measuring means for measuring the frequency of the beat signal, and the number of changes in the power of the beat signal at the frequency measured by the frequency measuring means Counting means for deriving the number of passing particles, speed calculating means for calculating the moving speed of the particles from the frequency of the beat signal measured by the frequency measuring means, It is characterized in that the occurrence of a beat signal in an optical device and a traveling direction determination means for determining a traveling direction of the particle.

  The fluid measuring device of the present invention is scattered by the flow path covered with a transparent plate that scatters light, the laser light source that irradiates the fluid in the flow path through the transparent plate with laser light, and the transparent plate. A light receiver that receives the received light and the light scattered by the particles contained in the fluid and converts it into an electrical signal, and a power spectrum that measures the power spectrum of the beat signal contained in the electrical signal obtained by the light receiver Measuring means, signal intensity average value measuring means for measuring the average intensity value of the beat signal, power spectrum of the beat signal measured by the power spectrum measuring means, and intensity of the beat signal measured by the signal intensity average value measuring means A flow rate calculating means for calculating the flow rate of the fluid from the average value, and a particle radius calculating means for calculating the radius of the particles from the flow rate calculated by the flow rate calculating means. The one in which the features.

  The fluid measurement method of the present invention is a laser irradiation step of irradiating a laser beam from a laser light source through the transparent plate to a flow path covered with a transparent plate that scatters light, and the light is scattered by the transparent plate. A light receiving step of receiving light and light scattered by particles contained in the fluid in the flow path with a plurality of light receivers arranged at a plurality of locations of the flow path and converting them into electrical signals, and the light receiving step A power spectrum measurement step for measuring the power spectrum of the beat signal included in the electrical signal obtained in step (b), a frequency measurement step for measuring the frequency of the beat signal, and the power of the beat signal at the frequency measured in the frequency measurement step. A counting step for deriving the number of passing particles by measuring the number of changes, and a beat signal measured in the frequency measuring step. A speed calculating step for calculating the moving speed of the particles from the frequency of the above, and a traveling direction determining step for determining the traveling direction of the particles from the generation status of beat signals in the plurality of light receivers. is there.

  The fluid measurement method of the present invention is a laser irradiation step of irradiating a laser beam from a laser light source through the transparent plate to a flow path covered with a transparent plate that scatters light, and the light is scattered by the transparent plate. A light receiving step of receiving light and light scattered by particles contained in the fluid in the flow path with a light receiver and converting the light into an electric signal, and the power of the beat signal included in the electric signal obtained in the light receiving step A power spectrum measurement step for measuring a spectrum; a signal intensity average value measurement step for measuring an average intensity value of the beat signal; and a power spectrum of the beat signal measured in the power spectrum measurement step and the signal intensity average value measurement step. The flow rate calculation step that calculates the flow rate of the fluid from the measured intensity average value of the beat signal, and the flow rate calculation step Is characterized in that the flow rate and a particle radius calculation step of calculating the radius of the particle.

  According to the present invention, a flow path covered with a transparent plate that scatters light is irradiated with laser light through the transparent plate, and scattered by light scattered by the transparent plate and particles contained in the fluid in the flow path. The moving light of the particles can be calculated by receiving the received light with a light receiver and converting it into an electrical signal and analyzing the frequency of the beat signal included in the electrical signal. As a result, in the present invention, the moving speed of the particles can be measured in a short time accurately and inexpensively using a measuring chip with a simple configuration.

  In the present invention, a laser beam is irradiated through a transparent plate to a channel covered with a transparent plate that scatters light, and is scattered by light scattered by the transparent plate and particles contained in the fluid in the channel. The received light is received by a light receiver and converted into an electric signal, and the fluid flow rate can be calculated by measuring the power spectrum of the beat signal included in the electric signal and the intensity average value of the beat signal. . As a result, in the present invention, it is possible to measure the flow rate of the fluid accurately and inexpensively in a short time using a measuring chip having a simple configuration.

  In the present invention, a laser beam is irradiated through a transparent plate to a channel covered with a transparent plate that scatters light, and is scattered by light scattered by the transparent plate and particles contained in the fluid in the channel. The received light is received by a plurality of light receivers arranged at a plurality of locations in the flow path and converted into an electric signal, and the power spectrum of the beat signal included in the electric signal and the frequency of the beat signal are measured. The number of passing particles, the moving speed, and the traveling direction can be measured. As a result, according to the present invention, it is possible to accurately and inexpensively measure the number of passing particles, the moving speed, and the traveling direction in a short time using a measuring chip having a simple configuration.

  In the present invention, a laser beam is irradiated through a transparent plate to a channel covered with a transparent plate that scatters light, and is scattered by light scattered by the transparent plate and particles contained in the fluid in the channel. The received light is received by a light receiver and converted into an electrical signal, and the radius of the particle can be calculated by measuring the power spectrum of the beat signal included in the electrical signal and the average intensity of the beat signal. . As a result, in the present invention, the radius of the particles can be measured in a short time accurately and inexpensively using a measuring chip having a simple configuration.

It is a figure explaining the principle of operation of the fluid measuring device concerning the 1st reference example of the present invention. It is sectional drawing which shows the structure of the optical part of the fluid measuring device which concerns on the 1st reference example of this invention. It is a block diagram which shows the structure of the arithmetic unit used with the fluid measuring device which concerns on the 1st reference example of this invention. It is a figure which shows the example of the power spectrum of a beat signal. It is a block diagram which shows the structure of the arithmetic unit used with the fluid measuring device which concerns on the 2nd reference example of this invention. It is a figure which shows the measurement result of the flow volume of the fluid in the 2nd reference example of this invention. It is a figure which shows the example of the power spectrum of the beat signal measured in the case of particle passage. It is the top view and sectional drawing which show the structure of the optical part of the fluid measuring device which concerns on the 1st Embodiment of this invention. It is a block diagram which shows the structure of the arithmetic unit used with the fluid measuring device which concerns on the 1st Embodiment of this invention. It is a figure which shows the relationship between a particle diameter and a flow volume. It is a block diagram which shows the structure of the arithmetic unit used with the fluid measuring device which concerns on the 2nd Embodiment of this invention.

[ First Reference Example ]
Hereinafter, the present invention will be described in more detail with reference to the drawings. FIG. 1 is a diagram for explaining the operation principle of a fluid measuring device according to a first reference example of the present invention. The fluid measuring device includes a light source 1, a light receiver 2, and an inanimate body 3 that is disposed under the light source 1 and the light receiver 2 and scatters light.
The light from the light source 1 is applied to the inanimate body 3 and is also applied to the moving object 4 (particles in the fluid to be measured) moving under the light source 1 and the light receiver 2. And scattered by each of the fluid bodies 4.

  The light scattered by the inanimate body 3 and the flowing object 4 is received by the light receiver 2 and converted into an electrical signal. At this time, there are two types of light incident on the light receiver 2. One is scattered light from the flowing object 4 (moving particles in the fluid), and the other is scattered light from the inanimate body 3. Scattered light from the flowing object 4 causes a frequency shift due to the Doppler effect proportional to the moving speed of the flowing object 4. However, the frequency of the scattered light from the inanimate body 3 is unchanged. When such light having very close optical frequencies interfere with each other, a beat with a period inversely proportional to the difference in optical frequencies occurs.

The frequency of light itself is several hundred THz and cannot be directly measured by an electronic circuit. However, since the typical frequency of a beat is several tens of kHz or less, the intensity of reflected light incident on the light receiver 2 is oscillated. It can be measured. Assuming that the frequency of light in the light source 1 is ω ₀ , the moving speed of the flowing object 4 (that is, the flow velocity of the fluid) is v, the speed of light is c, and the refractive index of the fluid is n, the frequency ω of the beat signal obtained by the light receiver 2. _ds is expressed by the following equation.

For example, assuming that the flow velocity v = 0.01 [m / s], the wavelength λ = 850 nm, the light velocity c = 3 × 10 ⁸ [m / s], and the refractive index n = 1.3, ω ₀ = c / λ = Since 353 [THz], ω _ds = 15.3 [kHz], which is a frequency within a range that can be detected by an electronic circuit.

  In the present invention, the interference between the light scattered and returned by the moving object 4 and subjected to the Doppler shift and the light scattered and returned by the stationary inanimate body 3 are used, so either one of the lights. If the signal is extremely strong and the other light is extremely weak, the beat signal cannot be clearly obtained, so measurement is impossible. Therefore, it is necessary that the intensity of both lights be comparable so that they can be compared.

Next, FIG. 2 shows the configuration of the fluid measuring device of this reference example using the above principle. As described in FIG. 1, the light source 1 and the light receiver 2 are arranged adjacent to each other. If each of the light source 1 and the light receiver 2 is a bare chip, the distance between the centers is, for example, about 0.5 mm to 2 mm. The light source 1 and the light receiver 2 are installed on the measurement chip 5. The measuring chip 5 has a laminated structure, a substrate 6 having a size of about several centimeters square, a microchannel 7 disposed on the substrate 6, and made of, for example, glass disposed on the microchannel 7. The transparent plate 8 and the light source 1 and the light receiver 2 installed on the transparent plate 8 are provided.

  The microchannel 7 is formed in a flat channel-forming member (not shown) stacked on the substrate 6. Examples of the material for the substrate 6 and the flow path forming member include silicon. When a fluid containing particles 9 that are fluid objects is introduced into the microchannel 7, the fluid flows through the microchannel 7. The flat transparent plate 8 is laminated on the flow path forming member. The light source 1 and the light receiver 2 are installed at positions on the microchannel 7.

  Irradiation of light from the light source 1 to the particles 9 and reception of scattered light from the particles 9 are performed via the transparent plate 8. That is, the transparent plate 8 has a property transparent to the light from the light source 1. However, at least a region irradiated with light from the light source 1 in the entire region of the transparent plate 8 is subjected to frosted glass processing so that scattered light is appropriately generated. Since this scattered light is scattered light from the stationary transparent plate 8, no Doppler shift occurs. That is, the transparent plate 8 functions as the inanimate body 3 described above.

  On the other hand, the light that is irradiated from the light source 1 through the transparent plate 8 to the particles 9 and scattered by the particles 9 causes a Doppler shift. The light causing the Doppler shift passes through the transparent plate 8 again. However, as described above, the light from the light source 1 to the frosted glass processed portion of the transparent plate 8 and scattered by the frosted glass processed portion does not cause a Doppler shift. The light scattered by the transparent plate 8 and the light scattered by the particles 9 are received by the light receiver 2 and converted into electrical signals. As described above, it is possible to generate scattered light from an inanimate object by applying frosted glass processing to the transparent plate 8, and to obtain scattered light having an intensity comparable to that of the scattered light subjected to Doppler shift by the particles 9. As a result, a beat signal that can be detected by the light receiver 2 is obtained.

If the frequency ω _{ds of the} beat signal can be obtained, the moving speed v of the particle 9 can be calculated from the equation (1). FIG. 3 is a block diagram showing the configuration of the arithmetic unit used in the fluid measuring instrument of this reference example . The arithmetic device 10 includes a frequency measurement unit 11 and a speed calculation unit 12. The frequency measuring unit 11 measures the frequency of the intensity fluctuation of the electric signal obtained by the light receiver 2, that is, the frequency ω _{ds of the} beat signal. As a frequency measurement method, for example, there is FFT (Fast Fourier Transform). As will be described in the power spectrum described later, the frequency components of the beat signal are distributed over a wide frequency range, but here, a representative value of the frequency components may be adopted as the frequency of the beat signal.

The speed calculation unit 12 calculates the moving speed v of the particles 9 from the frequency ω _{ds of the} beat signal measured by the frequency measurement unit 11.
Thus, in this reference example , the moving speed v of the particles 9 can be measured in a short time. Further, since the conventional moving image analysis such as μTAS is not required, the measurement can be realized with a computer having a lower calculation ability than the conventional one, and the cost of the fluid measuring device can be reduced.

As an alternative to the frosted glass processing of the transparent plate 8, a material in which scattering particles are dispersed and arranged in the transparent glass may be used as the transparent plate 8. Due to the property of utilizing the light interference effect, when a light source having a wide emission wavelength width such as a light emitting diode or an incandescent light bulb is used, the above effect cannot be obtained. Therefore, a laser diode is used as the light source 1. In this reference example , a light source 1 made of a laser diode and a light receiver 2 made of a photodiode each use a bare chip (die).

[ Second Reference Example ]
In the first reference example , the method for measuring the moving speed of the particles has been described. Next, the method for measuring the flow rate of the fluid will be described with reference to FIG. Also in this reference example , the configuration of the optical part of the fluid measuring device is as shown in FIG. As described in the first reference example , the frequency of the beat signal obtained as a result of homodyne interference between scattered light with Doppler shift and scattered light without Doppler shift has information on the velocity of the particles.

  The power spectrum of the beat signal of a typical measurement example is shown in FIG. The horizontal axis of this power spectrum is frequency, and the vertical axis is power. Since the frequency of the beat signal is proportional to the particle velocity as shown in equation (1), the horizontal axis in FIG. 4 can be regarded as the particle velocity, and the vertical axis as the number of particles having the velocity component. it can. Therefore, it can be said that FIG. 4 is a velocity distribution function curve.

Here, the sum of products of the respective velocity components and the number of particles is proportional to the flow rate of the fluid. However, since the intensity of the beat signal is proportional to the light intensity (I (t)), the above sum is calculated as the square of the average value of the signal intensity (<I (t)>) so as not to depend on the light intensity. It is necessary to divide by ² ). An equation for obtaining the flow rate F of the fluid is shown below.

Equation (2) calculates the product of the frequency ω of the beat signal and the power P (ω) of the beat signal at the frequency ω for each frequency ω, obtains the sum of the products obtained for each frequency ω, and sums up the products. Is divided by the square of the intensity average value of the beat signal <I (t)> ² , it is shown that the fluid flow rate F is proportional to the calculation result. Therefore, if the power spectrum of the beat signal and the average intensity value of the beat signal can be obtained, the fluid flow rate F can be calculated from the equation (2).

FIG. 5 is a block diagram showing the configuration of the arithmetic unit used in the fluid measuring instrument of this reference example . The arithmetic device 10 a includes a power spectrum measurement unit 13, a signal intensity average value measurement unit 14, and a flow rate calculation unit 15. The power spectrum measuring unit 13 measures the power spectrum of the intensity fluctuation of the electric signal obtained by the light receiver 2, that is, the power spectrum of the beat signal. The signal intensity average value measurement unit 14 measures the intensity average value of the fluctuation of the electric signal obtained by the light receiver 2, that is, the intensity average value of the beat signal.

  The flow rate calculation unit 15 calculates the fluid flow rate F from the beat signal power spectrum measured by the power spectrum measurement unit 13 and the beat signal strength average value measured by the signal strength average value measurement unit 14 according to Equation (2). calculate.

The result of measuring the flow rate F of the fluid using the method of this reference example is shown in FIG. FIG. 6 shows the measurement result when the cross-sectional area of the microchannel 7 is 0.5 mm ² . The horizontal axis of FIG. 6 is the true value of the flow rate F, and the vertical axis is the measured value of this reference example . According to FIG. 6, it can be seen that there is a positive correlation between the true value and the measured value of this reference example when the flow rate F is small, and that the fluid measuring device of this reference example can be used as a flow meter. .

  The measured value is saturated where the flow rate F is large, but the reason why the measured value is saturated is that the frequency response of a preamplifier (not shown) that amplifies the output of the light receiver 2 is limited. It is not an essential problem. In order to convert the measured value obtained from the equation (2) into the true value of the flow rate F, it is necessary to multiply the measured value by a coefficient. The coefficient is calculated from the true value of the flow rate F and the equation (2). This can be determined by conducting in advance an experiment for obtaining the relationship with the obtained measurement value.

[ First Embodiment ]
In μTAS, the flow path is branched. It is necessary to measure the flow velocity before and after the branching and monitor the direction in which the particles travel. Therefore, by arranging one light source on the branch point of the flow path and arranging a plurality of light receivers before and after branching of the flow path, the change in the flow velocity of the particles before and after branching can be measured. In the present embodiment, silicon is used as the material of the measurement chip substrate and the flow path forming member. Silicon is inexpensive and easily forms a thermal oxide film on its surface, and since the component of the thermal oxide film is SiO _x, it is difficult to be affected by biological substances and water that are supposed to be measured, and conversely It does not affect the material flowing in the flow path. Furthermore, if a commercially available semiconductor process technology is used, a light receiver made of a photodiode can be easily formed on the substrate itself, and a circuit such as a preamplifier can be formed on the same chip.

In the second reference example , the case where the concentration of particles in the microchannel is as high as a colloidal solution is considered. However, in this embodiment, the particle diameter is large, such as a cell, and the particles are intermittent. Consider the case of passing through. If the particle size is large and the particles pass intermittently, such as cells, the estimation as described in the second reference example does not hold, but rather the cells that pass by following the time variation of the scattered light intensity. The number and the speed can be measured.

That is, as shown in FIG. 7, each time a cell passes, the shape of the power spectrum of the beat signal fluctuates up and down, so that the number of passing cells can be counted by counting the number of time changes. For example, in the example of FIG. 7, when attention is focused on a representative frequency omega ₁ of the beat signal, the power spectrum of the beat signal at the frequency omega ₁ is varied from P ₀ (ω) to P _{1 (ω).} Therefore, it can be counted that one cell has passed. In addition, the velocity of the passing cell can be measured by measuring the frequency of the beat signal at that time.

FIG. 8A is a plan view showing the configuration of the optical unit of the fluid measuring device of the present embodiment, and FIG. 8B is a cross-sectional view of the optical unit. Similar to the first reference example , the measurement chip 5 a has a laminated structure, and includes a substrate 6, a microchannel 7, a transparent plate 8 disposed on the microchannel 7, and a transparent plate 8. And a light receiver 2-1, 2-2, 2-3, 2-4 installed under the microchannel 7.

  In the present embodiment, the microchannel 7 is processed into a cross-like shape in plan view. The light source 1 is installed at a position on the intersection of the cross-shaped microchannel 7. On the other hand, the light receivers 2-1 to 2-4 are installed one by one at positions below the four corners of the microchannel 7. Signal receivers 16-1 to 16-4 are connected to the respective light receivers 2-1 to 2-4.

As in the first reference example , at least the region irradiated with the laser light from the light source 1 in the entire region of the transparent plate 8 is subjected to frosted glass processing so that scattered light is appropriately generated. ing. Since this scattered light is scattered light from the stationary transparent plate 8, no Doppler shift occurs. On the other hand, the laser beam that is irradiated from the light source 1 through the transparent plate 8 to the fluid containing the particles 9 and is scattered by the particles 9 causes a Doppler shift. The light scattered by the transparent plate 8 and the light scattered by the particles 9 are received by the light receivers 2-1 to 2-4 and converted into electrical signals.

  By simultaneously monitoring and comparing signals from the light receivers 2-1 to 2-4 at the four corners of the cross-shaped microchannel 7, the traveling direction and speed of the particles 9 can be measured simultaneously. For example, when the particles 9 pass from right to left in FIG. 8A and FIG. 8B, the two light receivers 2-1 on the right side before the particles 9 pass through the intersection of the microchannels 7-1. A beat signal is obtained from 2-2, and when the particle 9 passes through the intersection, beat signals are obtained from the four light receivers 2-1 to 2-4. Beat signals are obtained from the devices 2-3 and 2-4. Therefore, it can be seen that the particles 9 have passed through the microchannel 7 from right to left.

  When the particles 9 pass from the top to the bottom in FIG. 8A, the beat signals from the two light receivers 2-1 and 2-3 are passed before the particles 9 pass through the intersection of the microchannels 7. When the particle 9 passes through the intersection, beat signals are obtained from the four light receivers 2-1 to 2-4, and after the particle 9 passes through the intersection, the two light receivers 2-2 and 2-4 are obtained. A beat signal is obtained from. Therefore, it can be seen that the particles 9 have passed from the top to the bottom of FIG.

  FIG. 9 is a block diagram showing a configuration of an arithmetic device used in the fluid measuring device of the present embodiment. The arithmetic device 10 b includes a power spectrum measurement unit 17, a frequency measurement unit 18, a counting unit 19, a speed calculation unit 20, and a traveling direction determination unit 21. The power spectrum measurement unit 17 measures the power spectrum of the beat signal in the same manner as the power spectrum measurement unit 13. At this time, the light receiver used for the measurement of the power spectrum may be any one of the light receivers 2-1 to 2-4. The frequency measurement unit 18 measures the frequency of the beat signal in the same manner as the frequency measurement unit 11. At this time, the light receiver used for frequency measurement may be the same as the light receiver used by the power spectrum measurement unit 17.

The counting unit 19 derives the number of passing particles 9 by measuring the number of beat signal power changes at the frequency measured by the frequency measuring unit 18.
Similar to the velocity calculator 12, the velocity calculator 20 calculates the moving velocity of the particles 9 from the frequency of the beat signal measured by the frequency measuring unit 18.

The traveling direction determination unit 21 determines the traveling direction of the particles 9 from the generation state of the beat signal in each of the light receivers 2-1 to 2-4.
Thus, in the present embodiment, the number of passing particles 9, the moving speed, and the traveling direction can be measured simultaneously.

[ Second Embodiment ]
Even when there is no overall flow in a particle-containing fluid such as a colloidal suspension, the Doppler shift of scattered light is not lost due to Brownian motion. Brownian motion is a random motion of particles that occurs when fluid molecules (eg, water molecules) collide with particles from all directions due to thermal motion. Since it does not move in one direction for a certain period of time, it is not expressed in terms of speed. Because of the thermal motion, the higher the temperature, the more intense the collision of water molecules, and the smaller the particle shape, the less water resistance, so the intensity of particle fluctuation due to Brownian motion increases. The intensity of fluctuation is expressed as a diffusion coefficient. The diffusion coefficient D of Brownian motion is expressed by the following equation.

Here, k _B is the Boltzmann constant, T is the temperature, η is the viscosity coefficient of water, and r is the radius of the particle. Here, the flow rate is an index of the Doppler effect due to the motion of the particles, and is expressed as the intensity of the Brownian motion fluctuation, so the flow rate is related to the diameter of the particles. FIG. 10 shows the result of measuring the flow rate value of polystyrene latex particles having a diameter of 60 nm to 3000 nm by the method of the second reference example . The water temperature is constant at 25 degrees. As a rule of thumb, it has been found that there is a relationship of the following equation (4) by fitting the data of the particle diameter and the flow rate value.

  Here, α is a device-dependent proportional coefficient, and α = 11400. Using this rule of thumb, the particle radius can be determined by measuring the flow rate F. The result shown in FIG. 10 is a result measured at 25 degrees Celsius. As can be seen from the equation (3), the flow rate F and the particle diameter are dependent on temperature, so comparison is made under a constant temperature condition. There is a need to. Conversely, when the particle diameter is known, the temperature and the viscosity coefficient of the fluid can be estimated.

Also in the present embodiment, the configuration of the optical unit of the fluid measuring device is as shown in FIG. FIG. 11 is a block diagram showing a configuration of an arithmetic device used in the fluid measuring device of the present embodiment. The computing device 10 c includes a power spectrum measurement unit 13, a signal intensity average value measurement unit 14, a flow rate calculation unit 15, and a particle radius calculation unit 22. The operations of the power spectrum measurement unit 13, the signal intensity average value measurement unit 14, and the flow rate calculation unit 15 are as described in the second reference example .
The particle radius calculation unit 22 calculates the radius r of the particle 9 from the flow rate F calculated by the flow rate calculation unit 15 using Equation (4).

The arithmetic devices 10, 10a, 10b, and 10c described in the first and second reference examples and the first and second embodiments include, for example, a computer including a CPU, a storage device, and an interface, and hardware resources thereof. It can be realized by a program to be controlled. The CPUs of the arithmetic devices 10, 10a, 10b, and 10c execute the processes described in the first and second reference examples and the first and second embodiments in accordance with a program stored in the storage device.

  INDUSTRIAL APPLICABILITY The present invention is useful for measuring the dynamics of a fluid such as a reagent or a sample in a measurement chip for livestock / medical diagnosis or a measurement chip for chemical response detection. Further, the present invention can be used for μTAS that performs analysis using a measurement chip. For example, it can be used for μTAS for analyzing biological samples such as saliva, urine, blood and the like. According to the fluid measuring instrument and the fluid measuring method according to the present invention, the measurement speed, flow rate, number of passing particles, particle concentration, and particle diameter can be measured with a simple measuring chip. It is useful to apply to.

  DESCRIPTION OF SYMBOLS 1 ... Light source, 2, 2-1 to 2-4 ... Light receiver, 3 ... Inanimate body, 4 ... Flowing object, 5, 5a ... Measuring chip, 6 ... Substrate, 7 ... Micro flow path, 8 ... Transparent plate, 9 ... Particles, 10, 10a, 10b, 10c ... Arithmetic unit, 11, 18 ... Frequency measurement unit, 12, 20 ... Speed calculation unit, 13, 17 ... Power spectrum measurement unit, 14 ... Signal intensity average value measurement unit, 15 ... Flow rate calculation unit, 16-1 to 16-4 ... wiring, 19 ... counting unit, 21 ... traveling direction determination unit, 22 ... particle radius calculation unit.

Claims (4)

A channel covered with a transparent plate that scatters light,
A laser light source for irradiating the fluid in the flow path with laser light through the transparent plate;
A plurality of light receivers that are disposed at a plurality of locations in the flow path, receive light scattered by the transparent plate and light scattered by particles contained in the fluid, and convert the light into electrical signals;
Power spectrum measuring means for measuring the power spectrum of the beat signal included in the electrical signal obtained by the light receiver;
Frequency measuring means for measuring the frequency of the beat signal;
Counting means for deriving the number of passages of the particles by measuring the number of changes in the power of the beat signal at the frequency measured by the frequency measuring means,
Speed calculating means for calculating the moving speed of the particles from the frequency of the beat signal measured by the frequency measuring means;
A fluid measuring device, comprising: a traveling direction determination unit that determines a traveling direction of the particles from a generation state of beat signals in the plurality of light receivers. A channel covered with a transparent plate that scatters light,
A laser light source for irradiating the fluid in the flow path with laser light through the transparent plate;
A light receiver that receives light scattered by the transparent plate and light scattered by particles contained in the fluid and converts the light into an electrical signal;
Power spectrum measuring means for measuring the power spectrum of the beat signal included in the electrical signal obtained by the light receiver;
A signal intensity average value measuring means for measuring an average intensity value of the beat signal;
A flow rate calculating means for calculating a flow rate of the fluid from the power spectrum of the beat signal measured by the power spectrum measuring means and the intensity average value of the beat signal measured by the signal intensity average value measuring means;
A fluid measuring instrument comprising: a particle radius calculating means for calculating a radius of the particle from the flow rate calculated by the flow rate calculating means. A laser irradiation step of irradiating a laser beam from a laser light source through the transparent plate to a flow path covered with a transparent plate that scatters light;
Light scattered by the transparent plate and light scattered by particles contained in the fluid in the flow path are received by a plurality of light receivers arranged at a plurality of locations in the flow path and converted into electrical signals. A light receiving step;
A power spectrum measurement step for measuring the power spectrum of the beat signal included in the electrical signal obtained in this light receiving step;
A frequency measurement step for measuring the frequency of the beat signal;
A counting step for deriving the number of passages of the particles by measuring the number of changes in the power of the beat signal at the frequency measured in this frequency measurement step;
A speed calculating step for calculating the moving speed of the particles from the frequency of the beat signal measured in the frequency measuring step;
A fluid direction measuring method comprising: a traveling direction determination step of determining a traveling direction of the particles from a generation state of beat signals in the plurality of light receivers. A laser irradiation step of irradiating a laser beam from a laser light source through the transparent plate to a flow path covered with a transparent plate that scatters light;
A light receiving step of receiving light scattered by the transparent plate and light scattered by particles contained in the fluid in the flow path with a light receiver and converting the light into an electrical signal;
A power spectrum measurement step for measuring the power spectrum of the beat signal included in the electrical signal obtained in this light receiving step;
A signal intensity average value measuring step for measuring an average intensity value of the beat signal;
A flow rate calculating step for calculating a fluid flow rate from the power spectrum of the beat signal measured in the power spectrum measuring step and the intensity average value of the beat signal measured in the signal intensity average value measuring step;
A fluid measurement method comprising: a particle radius calculation step of calculating a radius of the particle from the flow rate calculated in the flow rate calculation step.

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