JP2005257408A - Method and apparatus for dispensing very small amount of liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dispenser capable of precisely and quantitatively dispensing a very small amount of a liquid from a liquid lump exceeding a target liquid amount, and provide a dispensing method of a very small amount of the liquid. <P>SOLUTION: In the dispenser 1 for dispensing a very small amount of the liquid equipped with a holding part 3 connected through a narrow flooding part 3a for holding the liquid Lq and a comb tooth electrode 4 for emitting sonic waves to the narrow flooding part 3a from the direction crossing the narrow flooding part 3a, and in the dispensing method of a very small amount of the liquid, the holding part 3 and the comb tooth electrode 4 are provided on a solid substrate 2. In the dispensing method, sonic waves are emitted to the liquid held to the holding part 3 formed on the solid substrate 2 and connected through the narrow flooding part 3a from the direction crossing the narrow flooding part 3a to dispense a very small amount of the liquid Lqm from the liquid by acoustic radiation pressure due to sonic waves. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a trace liquid sorting device and a trace liquid sorting method for quantitatively sorting a trace amount of liquid from a large volume of liquid mass.

  In conventional biochemical micro-analysis systems (Micro Total Analysis Systems: μTAS), in order to perform accurate analysis, it is desirable to accurately sort or dispense a small amount of reaction solution to be analyzed in a desired volume. ing. In order to meet such a demand, conventionally, for example, an apparatus that uses a pulse-driven piezoelectric body and ejects a minute amount of droplets through a nozzle by ultrasonic energy focused on the liquid surface has been proposed ( For example, see Patent Literature 1 and Non-Patent Literature 1). At this time, the minute droplet is generated by an acoustic radiation pressure that is a force generated when the propagation of the sound wave, which is a flow of wave energy, is blocked by the object, and is a force that pushes the object in the propagation direction of the sound wave. That is, since the propagation of the sound wave propagating in the liquid is blocked at the gas-liquid interface where the liquid contacts the gas, the gas-liquid interface is pushed in the propagation direction by the sound wave. For this reason, in the devices disclosed in Patent Document 1 and Non-Patent Document 1, the ultrasonic energy is focused on the liquid surface, which is the gas-liquid interface, so that a very strong pressing force exceeding the surface tension is applied. A small amount of liquid droplets is separated from the continuous liquid by acting locally on the gas-liquid interface.

By the way, according to Non-Patent Document 2 cited in Patent Document 1, if the energy focusing diameter d, the focal length L, the speed of sound C in the liquid, the lens diameter D, and the driving frequency F, the energy focusing diameter d is expressed by the following equation. Determined by.
d = 2.44L ・ C / (D ・ F) ………… (1)
Patent Document 1 describes that the diameter of a droplet discharged from a nozzle is linearly proportional to the energy focusing diameter d.

JP 2003-121440 A `` 10th International Conference on Solid-State Sensors and Actuators '', P. 1784-1788, `` Ejection Characteristics of Micromachined Acoustic-Wave Liquid Ejector '' Junichi Miyoshi, supervised by Toshio Fujiyoshi, “Sonics Technology Manual”, Nikkan Kogyo Shimbun, November 25, 1960, p. 171

  However, the surface tension of the droplet becomes dominant as the diameter decreases. For this reason, the relationship of the formula (1) does not necessarily apply to the diameter of the droplets ejected from the nozzle. For example, in Non-Patent Document 1, when formula (1) is applied, the calculated droplet diameter is 1.5 μm, but the actual droplet diameter is at least about 10 μm. For this reason, the conventional apparatus was not necessarily satisfactory in the point of the precision at the time of fractionating a trace amount liquid.

  The present invention has been made in view of the above, and a trace liquid sorting device and a trace liquid sorting method capable of accurately and quantitatively sorting a trace amount of liquid from a liquid mass exceeding a target liquid volume The purpose is to provide.

  In order to solve the above-described problems and achieve the object, one aspect of the trace liquid dispensing apparatus according to the present invention is connected via a narrow portion, and intersects the narrow portion with a holding portion that holds liquid. Sound wave generating means for generating sound waves from the direction toward the narrow portion is provided on the surface of the solid substrate.

  Further, in order to solve the above-described problems and achieve the object, one aspect of the trace liquid sorting method according to the present invention is held by a holding unit formed on a solid substrate and connected via a narrow portion. A method for separating a small amount of liquid using sound waves, the step of emitting sound waves from the direction intersecting the narrow portion toward the narrow portion, and a minute amount from the liquid by acoustic radiation pressure of the sound waves And the step of dispensing the liquid.

  According to the trace liquid fractionating device of the above aspect and the trace liquid fractionation method of the above aspect, since the trace liquid is fractionated from the liquid present in the narrow part among the liquid mass exceeding the target liquid volume, the quantitative determination is performed. The liquid is dispensed with high accuracy.

  Moreover, one aspect of the trace liquid sorting device according to the present invention is characterized in that, in the above invention, the sound wave generating means is provided on the first solid substrate together with the holding portion.

  Moreover, one aspect of the trace liquid sorting apparatus according to the present invention is characterized in that, in the above invention, the sound wave generating means and the holding part are arranged on the same plane of the solid substrate.

  Moreover, one aspect of the trace liquid sorting apparatus according to the present invention is characterized in that, in the above invention, the sound wave generating means is provided on a second solid substrate different from the holding portion.

  Further, in one aspect of the trace liquid sorting apparatus according to the present invention, in the above invention, the sound wave generating unit generates a sound wave from the direction orthogonal to the narrow portion toward the liquid in the narrow portion. And

  Further, in one aspect of the trace liquid sorting apparatus according to the present invention, in the above invention, the difference in acoustic impedance between the solid substrate and the liquid is the acoustic impedance between the solid substrate and the atmosphere in contact with the solid substrate. It is smaller than the difference and smaller than the difference in acoustic impedance between the liquid and the atmosphere in contact with the liquid.

  Moreover, in one aspect of the trace liquid sorting apparatus according to the present invention, in the above invention, the sound wave generation unit selectively directs the generated sound wave to a narrow portion of a droplet held in the holding unit. It is characterized by.

  According to another aspect of the present invention, there is provided an aspect of the present invention, wherein the acoustic wave generating means is a surface acoustic wave generating means for generating a surface acoustic wave.

  Moreover, one aspect of the trace liquid sorting apparatus according to the present invention is characterized in that, in the above invention, the surface acoustic wave generating means is a comb electrode in which linear electrodes are arranged on a plane. .

  Further, according to one aspect of the trace liquid sorting apparatus according to the present invention, in the above invention, the surface acoustic wave generating means is a comb electrode in which curved electrodes are arranged on a plane, and the narrow portion The surface acoustic wave is focused on an edge portion of the liquid away from the surface acoustic wave generating means.

  According to another aspect of the present invention, the first solid substrate and the second solid substrate are in close contact via a substance having an acoustic impedance close to that of the liquid. It is characterized by.

  In addition, in one aspect of the trace liquid sorting apparatus according to the present invention, in the above invention, the sound wave generating unit is a surface acoustic wave generating unit that generates a surface acoustic wave, and has a substance having an acoustic impedance close to that of the liquid. Is set to a predetermined thickness with reference to the wavelength of the longitudinal acoustic wave generated by converting the surface acoustic wave as a sound source at the joint surface between the first solid substrate and the second solid substrate. It is characterized by that.

  Further, in one aspect of the trace liquid sorting apparatus according to the present invention, in the above invention, the sound wave generating unit is a surface acoustic wave generating unit that generates a surface acoustic wave, and the first solid substrate is It is formed of a material having acoustic impedance that allows transmission of longitudinal acoustic waves generated by converting the surface acoustic waves at the joint surface between the first solid substrate and the second solid substrate, or acoustic impedance close to that of the liquid. It is characterized by being.

  Further, in one aspect of the trace liquid sorting apparatus according to the present invention, in the above invention, the sound wave generating unit is a surface acoustic wave generating unit that generates a surface acoustic wave, and the first solid substrate is The thickness is set to a predetermined thickness with reference to the wavelength of the longitudinal acoustic wave generated by converting the surface acoustic wave at the joint surface between the first solid substrate and the second solid substrate. .

  Further, according to one aspect of the trace liquid sorting apparatus according to the present invention, in the above invention, the width of the liquid in the narrow portion when the liquid is held in the holding portion is a longitudinal wave using the surface acoustic wave as a sound source. It is a predetermined value determined by the wavelength of the sound wave.

  Moreover, in one aspect of the trace liquid sorting apparatus according to the present invention, in the above invention, the surface of the holding portion has hydrophilicity, and the surface of the portion adjacent to the holding portion has hydrophobicity. It is characterized by.

  Moreover, in one aspect of the trace liquid sorting device according to the present invention, in the above invention, the first solid substrate is inclined so as to be lowered from the sound wave generating means side toward the holding unit side, and The tilt angle at which the liquid is held by the holding portion is set.

  INDUSTRIAL APPLICABILITY The trace liquid sorting apparatus and trace liquid sorting method according to the present invention have an effect that a trace amount of liquid can be accurately and accurately sorted from a liquid mass exceeding a target liquid volume.

  Embodiments of a trace liquid sorting device and a trace liquid sorting method according to the present invention will be described below in detail with reference to the drawings.

(Embodiment 1)
First, a trace liquid sorting device and a trace liquid sorting method according to Embodiment 1 will be described. FIG. 1 is a perspective view of a trace liquid sorting apparatus for explaining Embodiment 1 according to the trace liquid sorting apparatus and trace liquid sorting method of the present invention. FIGS. 2-1 to 2-4 are plan views showing the shape of a holding part for holding a liquid in the trace liquid sorting apparatus. FIG. 3 is a front view showing the shape of the liquid held in the holding unit. FIG. 4 is a plan view showing the holding unit, the sound wave generating means, and the divided trace liquid.

  As shown in FIG. 1, a trace liquid sorting device (hereinafter simply referred to as “sorting device”) 1 generates a liquid holding unit 3 and a sound wave generating means, here, a surface acoustic wave on the upper surface of a solid substrate 2. IDT (Inter Digital Transducers) comb electrodes (hereinafter simply referred to as “comb electrodes”) 4 are provided.

  The solid substrate 2 is arranged so as to be lowered from the comb electrode 4 side toward the holding unit 3 side and inclined at an angle θ so that the liquid is held by the holding unit 3. The solid substrate 2 is provided with a holding portion 3 and a comb-like electrode 4 on the upper surface, and a portion adjacent to the holding portion 3 is subjected to a hydrophobization treatment and has hydrophobicity. Hydrophobization treatment is performed by forming a comb-teeth electrode 4 on the surface of the solid substrate 2 and then spin-coating a water-repellent agent made of a fluororesin polymer, or applying an amorphous carbon film (DLC) by low-temperature coating by plasma CVD. It is done by forming. Here, the solid substrate 2 is, for example, a solid substrate such as silicon or glass used in semiconductor manufacturing technology, or a metal layer or an insulating layer formed on these solid substrates, lithium niobate crystal, zinc oxide, titanic acid. A piezoelectric solid substrate such as lead zirconate titanate (PZT), or a substrate provided with a quartz layer or a metal layer on a part of the piezoelectric substrate is used.

  The holding unit 3 is a part on which a liquid to be obtained by dividing and obtaining a trace amount liquid using a micropipetter, a syringe dispenser, etc., has hydrophilicity, and as shown in FIGS. 1 and 2-1. The receiving portion 3b is connected through the narrow portion 3a. The holding unit 3 has hydrophilicity, whereas the portion adjacent to the holding unit 3 of the solid substrate 2 is subjected to a hydrophobic treatment. Therefore, when the liquid is placed on the holding unit 3, the solid substrate 2 forms liquid droplets as shown in FIG. 3, the amount of liquid in the narrow portion 3 a is small, and the liquid is held in a shape in which the receiving unit 3 b is raised. Is done. For this reason, the liquid held in the holding part 3 is easily divided into small liquids from the narrow part 3a having a small amount. The holding unit 3 is formed on the surface of the solid substrate 2 by applying a glass-based coating on the corresponding part of the solid substrate 2 or by forming an oxide film or the like on the surface when a silicon substrate is used as the solid substrate 2. Provided.

  Here, as shown in FIG. 2-2, the holding part 3 may have a shape in which the receiving part 3b is connected to the narrow part 3a in a dotted shape. In this case, when the liquid is placed on the holding unit 3, the liquid Ln existing in the narrowed portion 3a slightly protrudes from the narrowed portion 3a as shown by the dotted line, but is smaller than the receiving portion 3b, so that the trace amount liquid is divided. There is no problem. Further, as shown in FIG. 2-3, the holding portion 3 is formed so that the narrow portion 3a is longer than that shown in FIG. 2-1, or the narrow portion 3a has a minute holding portion as shown in FIG. 3c may be formed. With such a structure, the holding unit 3 has a small cross-sectional area of the liquid in a plane orthogonal to the narrowed portion 3a, and a trace amount of liquid can be more easily divided from the placed liquid.

  As shown in FIG. 1, the comb electrode 4 includes linear electrodes 4 a and 4 b that are alternately engaged in a comb shape at a pitch of several μm, and is connected to an external power source 7 by a wiring 6. . The comb electrode 4 is provided on the surface of the solid substrate 2 so as to be offset from the holding portion 3 so that the narrow portion 3a exists at a position intersecting the path of the generated surface acoustic wave. That is, as shown in FIG. 4, the comb electrode 4 has a liquid Ln in which the linear electrodes 4a and 4b formed on the plane overlap and an effective area Ae for generating surface acoustic waves is present in the narrow portion 3a. It is provided so as to coincide with the length Lg. Thereby, the comb-teeth electrode 4 is generated by selectively directing surface acoustic waves to the narrow portion 3a, so that the trace amount liquid Lqm is divided from the narrow portion 3a as shown in FIGS.

  In the sorting apparatus 1 configured as described above, for example, when a high-frequency AC electric field of about several MHz to several hundred MHz is applied from the power source 7 to the comb electrode 4, the frequency is determined by the surface acoustic wave velocity and the comb electrode 4. When a resonance condition equal to the ratio of the distances between the electrodes 4a and 4b is substantially satisfied, a surface acoustic wave Ws is induced in the piezoelectric region of the solid substrate 2 as shown in FIG. The surface acoustic wave Ws propagates in two directions on the surface of the solid substrate 2 to both sides of the comb electrode 4 along the arrangement direction of the electrodes 4a and 4b that are engaged with each other. Of the surface acoustic waves Ws propagating in two directions, the surface acoustic wave Ws directed toward the holding unit 3 acts on the liquid Ln present in the narrow portion 3a as an external force for dividing the trace amount liquid Lqm.

Here, the propagation of the surface acoustic wave in the substance is performed when the microparticles in the substance vibrate in the traveling direction. Within a very limited time, there are dense and sparse parts in the vibrating microparticles, and the speed of progress in this sparse state is the speed of sound, and the relational expression of sound speed is C for sound speed (propagation speed). , K is the volume modulus, and ρ is the density,
C = (K / ρ) ^1/2 ......... (2)

When the surface acoustic wave propagates and the constituent molecules of the solid or liquid undergo a rough change, the pressure at each point increases or decreases. This pressure difference (pressure fluctuation from normal pressure) is called sound pressure, and the ratio of particle velocity to sound pressure is called acoustic impedance. In the case of a plane wave, the acoustic impedance Z is determined by the product of the medium density ρ and the sound velocity C, and is given by the following equation.
Z = ρ · C ……………………… (3)

  Therefore, for example, when the sound speed and density are large, the acoustic impedance increases. The acoustic impedance is a physical property value that determines the transmission efficiency of surface acoustic waves in a substance. As described above, if the difference in acoustic impedance between two kinds of substances in contact with each other is large, the acoustic impedance propagates on the surface of one substance. Surface acoustic waves do not propagate to the other. On the other hand, if the difference in acoustic impedance between the two types of substances is small, the surface acoustic wave that has propagated on the surface of one substance propagates to the other.

Therefore, when the acoustic impedances of the solid substrate 2 and the fluid in contact with the solid substrate 2 are greatly different, the surface acoustic wave Ws propagates while being confined in the depth region of about one wavelength from the surface of the solid substrate 2. On the other hand, when the acoustic impedance of the solid substrate 2 and the fluid in contact with the solid substrate 2 is close, the surface acoustic wave Ws leaks from the solid substrate 2 to the fluid side. In the sorting apparatus 1, except for the holding unit 3, the fluid with which the solid substrate 2 is in contact with the interface is an atmosphere typified by air / atmosphere, and the acoustic impedances of both are remarkably different. For this reason, the surface acoustic wave Ws propagates while being confined on the surface of the solid substrate 2. However, in the holding part 3, the fluid with which the solid substrate 2 contacts the interface is the liquid Lq, and the acoustic impedances of both are relatively close. For this reason, the surface acoustic wave Ws leaks to the liquid Lq side in the narrow portion 3a. However, since transverse waves such as surface acoustic waves cannot propagate in a fluid such as liquid Lq, mode conversion from transverse waves to longitudinal waves is performed at the interface between solid substrate 2 and liquid Lq according to Snell's law expressed by the following equation. Is done.
Sinθ _i / V _s = Sinθ _lt / V _l (4)

Here, θ _i is the incident angle of the surface acoustic wave at the interface incident on the liquid Lq from the solid substrate 2, θ _lt is the transmission angle of the longitudinal wave transmitted / leaked into the liquid Lq, and V _s is the surface of the solid substrate 2. The velocity of the elastic wave, V _l, is the velocity of the longitudinal wave in the liquid Lq.

  Thus, in the narrow portion 3a, as shown in FIGS. 6 and 7, the longitudinal wave sound wave Wl whose mode has been converted is transmitted / propagated into the liquid Ln. At this time, the narrow portion 3a becomes the surface of the solid substrate 2 immediately below the liquid level in the vicinity of the gas-liquid interface. For this reason, the mode-converted longitudinal acoustic wave can efficiently change the gas-liquid interface of the liquid existing in the narrow portion 3a.

At this time, for example, if the longitudinal wave sound wave subjected to the mode conversion is about several MHz to several hundred MHz, it is possible to cause the liquid Lq to flow or to generate a change in the gas-liquid interface. In addition, if the longitudinal wave wave subjected to mode conversion is a repetitive pulse of about several milliseconds, it is possible to use the acoustic radiation pressure as physical energy for rocking or moving the liquid. Further, as indicated by the dotted line in FIG. 7, the longitudinal wave sound wave which has been mode-converted from the surface acoustic wave is transmitted / leaked from the solid substrate 2 into the liquid Lq with an angle θ _lt determined by the equation (4). At this time, when the surface acoustic wave is a Rayleigh wave, θ _i = 90 °, and the transmission / leakage angle is determined by the ratio of each sound velocity (V ₁ / V _s ). For this reason, the fractionation apparatus 1 divides a trace amount liquid from the liquid which exists in the narrow part 3a by radiating a longitudinal wave sound wave in a desired direction by appropriately selecting the velocity of the surface acoustic wave in the solid substrate 2. Can do.

  That is, in FIG. 3, the liquid Lq held in the holding unit 3 has a specifically reduced cross-sectional area in a plane perpendicular to the narrowed part 3 a in the narrowed part 3 a. For this reason, the sorting device 1 can separate the trace amount liquid Lqm from the liquid Lq as a droplet with a relatively small force. Here, in the narrow portion 3a, as shown in FIG. 7, acoustic radiation pressure is generated by the longitudinal wave sound wave W1 propagating in the liquid Ln existing in the narrow portion 3a as indicated by a dotted line. The acoustic radiation pressure acts on the liquid Lq as a force for separating the trace liquid Lqm along the traveling direction of the longitudinal wave sound wave.

  At this time, the traveling direction of the longitudinal wave sound wave is the width W direction of the liquid Ln existing in the narrow portion 3a in FIG. 7, and the acoustic radiation pressure of the longitudinal wave sound wave leaked to the liquid Lq from the surface of the solid substrate 2 is Decrease for a while along the traveling direction of the longitudinal sound wave from the position where leakage starts into the liquid. In general, longitudinal wave sound waves are assumed to leak into the liquid up to a distance of about 8 wavelengths from the leakage start position to the liquid Lq. Therefore, in FIG. 4, the width W of the liquid Lq present in the narrow portion 3a can be set to an appropriate value based on the wavelength of the longitudinal wave sound wave for this reason. Here, FIG. 4 shows the holding unit 3 that holds the liquid Lq, but FIG. 4 is a plan view, and at the same time, also shows a planar spread of the liquid Lq existing in the holding unit 3.

  Further, as shown in FIG. 1, the solid substrate 2 is disposed at a position where the comb-teeth electrode 4 is higher than the holding portion 3 by tilting the angle θ, and the surface excluding the holding portion 3 is hydrophobic (water repellent). )have. For this reason, the trace liquid Lqm separated by the surface acoustic wave easily flows down the surface of the solid substrate 2 due to gravity. Here, the angle θ for inclining the solid substrate 2 is set to an angle at which the liquid is held by the adsorptivity of the holding unit 3 having a hydrophilic surface and does not flow down in a state where the acoustic radiation pressure does not act on the liquid. Further, the surface of the solid substrate 2 through which the trace liquid Lqm divided from the edge of the narrow portion 3a passes is hydrophobized so that the fractionated trace liquid Lqm is adhered to the solid substrate 2 by adhesion. The solid substrate 2 can be transported without causing a decrease in volume.

  In the preparative device 1, the elements that are dominant in determining the volume of the minute liquid to be divided are arranged as follows. First, the cohesive force, which is a drag force when dividing a minute amount of liquid, is determined by the viscosity or surface tension of the liquid and the three-dimensional shape and size of the liquid existing in the narrow portion 3a. On the other hand, the magnitude of the force that attempts to separate the minute amount of liquid against the cohesive force is the vibration frequency and amplitude of the comb electrode 4 that determines the intensity of the acoustic radiation pressure, and the driving voltage of the comb electrode 4 is determined. Application time. The comb electrode 4 generates ultrasonic waves having a relatively high frequency, for example, a frequency of around 100 MHz, among ultrasonic transducers. At this time, the comb-tooth electrode having a withstand voltage against a high driving voltage is smaller than an ultrasonic vibrator formed of a piezoelectric material, and can efficiently apply acoustic radiation pressure near the narrow portion of the droplet to be operated. It is.

  In addition, the sorting device 1 can adjust the intensity of the acoustic radiation pressure acting on the liquid by selecting the amplitude of the comb electrode 4, that is, the magnitude of the driving voltage and the application time, and the dispensing volume of the trace liquid. Can be adjusted. Furthermore, as shown in FIG. 8, which is an enlarged perspective view of the narrow portion 3a, the sorting apparatus 1 has a three-dimensional shape and dimensions (for example, a width W, a length Lg, or the like) of the liquid Ln existing in the narrow portion 3a. The fractional volume of the trace liquid can be adjusted also by setting the cross-sectional area S) in the plane orthogonal to the narrow portion 3a.

  Other features of the sorting apparatus 1 are as follows: 1. For example, by electronically controlling the waveform of the drive voltage pulse applied to the comb electrode 4, the operating time of the acoustic radiation pressure on the liquid can be easily set. 2. The drive voltage pulse can be controlled by software, and 3. The surface of the solid substrate 2 on which the liquid is placed has no unevenness, so that there are advantages such as easy cleaning.

  Here, the sorting device 1 may use the comb-tooth electrode 5 shown in FIG. The comb electrode 5 has linear electrodes 5a and 5b that are longer in length L5 than the length Lg of the liquid Ln present in the narrow portion 3a and are alternately engaged in a comb shape at a pitch of several μm. The wiring 6 is connected to an external AC power source (not shown).

  When the comb electrode 5 is used in the sorting device 1, as shown in FIG. 9, the surface acoustic wave Ws is induced in a wide range along the length L 5 direction and propagates on the surface of the solid substrate 2. When the surface acoustic wave Ws reaches the holding unit 3, the longitudinal wave wave that has undergone mode conversion leaks into the liquid and divides the trace amount liquid Lqm from the liquid present in the narrow portion 3a. At this time, the longitudinal wave sound wave leaked to the liquid outside the narrow portion 3a generates an acoustic flow Fl due to the acoustic radiation pressure in the liquid. The acoustic flow Fl is considered to be a rotating flow in the same direction as the direction in which the trace amount liquid Lqm is divided. For this reason, it can be expected that the acoustic flow Fl exhibits an auxiliary function in dividing the trace liquid Lqm from the liquid. In the present embodiment, the sound wave is radiated so as to be orthogonal to the narrow part 3a so that the sorting accuracy is the best. However, if at least the sound wave is radiated so as to cross the narrow part 3a. Sorting is possible.

(Embodiment 2)
Next, a trace liquid sorting device and a trace liquid sorting method according to Embodiment 2 will be described. FIG. 10 is a perspective view showing the sorting apparatus according to the second embodiment. Here, in the following description, the same components as those of the sorting apparatus 1 are described with the same reference numerals.

  The sorting device 10 is provided with a comb-shaped electrode 11 on the solid substrate 2 as arc-shaped electrodes 11a and 11b that are alternately engaged in a comb-tooth shape with a pitch of several μm instead of the comb-tooth electrode 4. is there. Since the comb-shaped electrode 11 has the arcs 11a and 11b, the surface acoustic wave generated is related to the liquid Lq held in the holding unit 3 and the liquid comb-shaped electrode 11 existing in the narrow portion 3a. Focusing on the edge away from the surface, that is, the divided trace liquid Lqm side. For this reason, the sorting device 10 can separate the trace amount liquid Lqm from the liquid present in the narrow portion 3 a more efficiently than the sorting device 1.

(Embodiment 3)
Next, a trace liquid sorting device and a trace liquid sorting method according to Embodiment 3 will be described. FIG. 11 is a perspective view showing a sorting apparatus according to the third embodiment. FIG. 12 is a cross-sectional view of the sorting device cut across the narrow portion.

  The sorting device 15 is provided with a liquid holding unit 3 on the upper surface of the fixed substrate 16 at a position facing the narrow portion 3a, a comb electrode 4 on the upper surface of the fixed substrate 17, and the fixed substrates 16 and 17 are The acoustic matching layer 18 is in close contact. Here, the fixed substrate 16 has acoustic impedance that allows transmission of longitudinal acoustic waves generated by converting surface acoustic waves at the joint surfaces of the solid substrates 16 and 17, or acoustic impedance close to the liquid held in the holding unit 3. Or a predetermined thickness with reference to the wavelength of the longitudinal wave generated by the conversion of the surface acoustic wave. The solid substrates 16 and 17 are made of the same material as that of the solid substrate 2 and are lowered from the comb electrode 4 side toward the holding unit 3 side, and the angle θ so that the liquid Lq is held in the holding unit 3. It is arranged at an angle. The acoustic matching layer 18 is applied or filled between the solid substrates 16 and 17 to match the acoustic impedance and acoustically couple the solid substrates 16 and 17. The acoustic matching layer 18 is held by the holding unit 3. A material having an acoustic impedance close to that of a liquid is used, a surface acoustic wave generated by the comb electrode 4 is used as a sound source, and a predetermined wavelength is used with reference to the wavelength of the longitudinal wave sound wave generated by being converted at the joint surface of the solid substrates 16 and 17. Set to thickness. The acoustic matching layer 18 is water, silicon-based oil, synthetic rubber, or the like when the liquid that is held in the holding unit 3 and divides the trace amount liquid is water or the liquid that has an acoustic impedance close to water. An emulsion such as water and glycerin or an epoxy resin is used.

  Here, the attenuation of the acoustic energy transmitted from the solid substrate 17 to the solid substrate 16 is calculated from the above-described equations (2) and (3), and the physical property values such as the density and bulk modulus of the substance that becomes the acoustic matching layer 18; It depends on the wavelength of the surface acoustic wave propagating in the material. In order to suppress the attenuation of the propagated surface acoustic wave, it is desirable that the thickness of the acoustic matching layer 18 is small. For example, the acoustic matching layer 18 is appropriately based on the wavelength of the longitudinal wave generated by mode conversion at the joint surface of the solid substrates 16 and 17. It is possible to obtain a correct value. Moreover, when it is going to transmit acoustic energy from the solid substrate 17 to the solid substrate 16 efficiently, it is desirable that the difference in acoustic impedance between the two is small.

  Accordingly, as shown in FIG. 12, the sorting device 15 has the surface acoustic waves generated by the comb electrodes 4 on the fixed substrate 17 because the solid substrates 16 and 17 are in close contact with each other via the acoustic matching layer 18. Ws passes through the fixed substrate 16 and reaches the liquid held in the holding unit 3, and separates the trace amount liquid Lqm from the liquid existing in the narrow portion 3a. At this time, the surface acoustic wave generated by the comb-tooth electrode 4 reaches the acoustic matching layer 18 existing on the joint surface between the solid substrate 16 and the solid substrate 17. For this reason, the solid acoustic wave that has reached the acoustic matching layer 18 is mode-converted from a transverse wave to a longitudinal wave or a mixed wave in which longitudinal and transverse waves are mixed. Of these longitudinal waves or mixed waves, only the mode-converted longitudinal wave sound wave Wl leaks to the solid substrate 16 and repeats reflection in the solid substrate 16, and proceeds while decreasing for a while. The longitudinal sound wave W1 that has reached the holding unit 3 in this manner leaks into the liquid Lq on the holding unit 3. On the other hand, the transverse wave sound wave Wt converted in the acoustic matching layer 18 is converted again into the longitudinal wave sound wave Wl for a while while propagating through the acoustic matching layer 18 and leaks to the solid substrate 16 and is repeatedly reflected in the solid substrate 16 for a while. Progress while decreasing.

  At this time, the liquid held in the holding part 3 has a specifically small cross-sectional area in the narrow part 3a in the plane orthogonal to the narrow part 3a, and the liquid Ln held in the narrow part 3a has a binding energy higher than that of other parts. Is small. For this reason, the trace amount liquid Lqm is separated from the liquid held in the narrow portion 3a by the acoustic radiation pressure of the longitudinal wave sound wave W1 (see FIG. 11).

  In the first embodiment, the material of the solid substrate 2 must be selected in consideration of both ease of surface treatment and piezoelectricity. However, in the present embodiment, since the first solid substrate on which the holding unit 3 is provided and the second solid substrate on which the comb electrode 4 is provided are separate substrates, the first solid substrate is subjected to surface treatment. However, the material of the second solid substrate may be selected for the purpose of the processability and piezoelectricity of the comb electrode, and there is an advantage that the range of selection of the material constituting the device is widened.

(Embodiment 4)
Next, a trace liquid sorting device and a trace liquid sorting method according to Embodiment 4 will be described. FIG. 13 is a perspective view showing a sorting apparatus according to the fourth embodiment.

  As shown in FIG. 13, the sorting device 20 replaces the comb-teeth electrode provided on the solid substrate 17 with the comb-teeth electrode 4, and uses the comb-teeth electrode 11 to closely contact the fixed substrates 16 and 17 via the acoustic matching layer 18. Is. Therefore, since the electrodes 11a and 11b of the comb electrode 11 are formed in an arc shape, the sorting device 20 has the generated surface acoustic wave in the narrow portion 3a with respect to the liquid Lq held in the holding portion 3. It converges on the edge away from the comb electrode 11 of the liquid, that is, on the divided minute liquid Lqm side. For this reason, the sorting device 20 mode-converts the surface acoustic wave generated by the comb electrode 11 by the acoustic matching layer 18 and converts the mode-converted longitudinal wave sound wave Wl from the solid substrate 16 to the liquid Lq on the holding unit 3. The trace amount liquid Lqm is divided from the narrow portion 3a by leaking into the narrow portion 3a.

(Embodiment 5)
Next, a trace liquid sorting device and a sorting method according to Embodiment 5 will be described. FIG. 14 is a perspective view showing a sorting apparatus according to the fifth embodiment.

  As shown in FIG. 14, the sorting device 25 is the same as the sorting device 10 according to the second embodiment, except that the comb-tooth electrode provided on the substrate 2 is replaced by the comb-tooth electrode 4 and the comb-tooth electrode 4 is used. An Lqm guide groove 2a is provided. The guide groove 2 a guides the movement of the trace amount liquid divided from the liquid held in the holding unit 3. Therefore, in the sorting device 25, the discharge path of the divided trace liquid is stabilized. Here, the configuration of the fifth embodiment can also be applied to the second to fourth embodiments.

(Embodiment 6)
Next, a trace liquid sorting device and a sorting method according to Embodiment 6 will be described. FIG. 15 is a perspective view showing a sorting apparatus according to the sixth embodiment.

  As shown in FIG. 15, in the sorting apparatus 10 according to the second embodiment, the sorting apparatus 30 has an electrode array 8 for carrying out a small amount of liquid to be divided starting from the vicinity of the narrow portion 3a on the surface of the fixed substrate 2. Is provided. The electrode array 8 has a plurality of electrodes 8a, and sequentially carries out the discharge by applying an electrostatic force to the divided trace liquid by sequentially switching the polarity of the adjacent electrodes. For this reason, the sorting apparatus 30 does not need to place the fixed substrate 2 in an inclined manner.

(Embodiment 7)
Next, a trace liquid sorting device and a sorting method according to Embodiment 7 will be described. FIG. 16 is a perspective view showing a sorting apparatus according to the seventh embodiment.

  As shown in FIG. 16, the sorting device 35 is provided with the holding portions 3 that hold the liquid Lq on both sides of the fixed electrode 2 sandwiching the comb electrode 4 in the sorting device 1 of the first embodiment. The electrode array 8 is provided to carry out a small amount of liquid to be divided starting from the vicinity of 3a. Accordingly, the sorting device 35 divides the two trace liquids Lqm from the liquid existing in the narrow portion 3a in the opposite directions simultaneously by driving the comb-teeth electrode 4, and the divided trace liquid Lqm is divided into each electrode array. 8 can be carried out. Here, the configuration of the seventh embodiment can also be applied to the third embodiment.

(Embodiment 8)
Next, a trace liquid sorting device and a sorting method according to Embodiment 8 will be described. FIG. 17 is a perspective view showing a sorting apparatus according to the eighth embodiment. FIG. 18A is a diagram illustrating a shape of a slit provided in the holding wall. 18-2 is a figure which shows the shape of the opening provided in the holding wall.

  As shown in FIG. 17, in the sorting apparatus 10 according to the second embodiment, the sorting device 40 is provided with a wall 2b surrounding the holding portion 3 on the fixed substrate 2, and at a position corresponding to the narrow portion 3a of the wall 2b. A slit 2c (see FIG. 18-1) is formed. The sorting device 40 can increase the amount of liquid that can be held in the holding unit 3 by providing such a wall 2 b on the fixed substrate 2. Further, by providing the slit 2c on the wall 2b, the surface acoustic wave generated by the comb-tooth electrode 11 is directed only to the slit 2c portion of the liquid Lq held by the holding portion 3, and the liquid in the slit 2c portion. A minute amount of liquid is separated out against the cohesive force of. Note that the configuration of the eighth embodiment can also be applied to the first, third, and fourth embodiments.

  Here, the wall 2b may be provided with an opening 2d shown in FIG. 18-2 instead of the slit 2c. At this time, the cohesive force of the liquid existing in the slit 2c or the opening 2d portion is determined by the viscosity or surface tension of the liquid and the shape and size of the slit 2c or the opening 2d portion. At this time, as a shape serving as one element for determining the cohesive force of the liquid, as shown in FIGS. 18A and 18B, in the case of the slit 2c, the shape is a height Hsl and a width Wsl. In the case of 2d, it is the height Hop and the curvature at the upper arch portion.

(Embodiment 9)
Next, a trace liquid sorting device and a sorting method according to Embodiment 9 will be described. FIG. 19 is a perspective view showing a sorting apparatus according to the ninth embodiment.

  As shown in FIG. 19, the sorting device 45 uses a thick material for the fixed substrate 16 in the sorting device 15 of the third embodiment, and uses the liquid holding groove 16a and the liquid held in the holding groove 16a. This is a modified example in which a guide groove 16b for guiding the movement of the minute liquid to be divided is provided. The holding groove 16a has the same shape as the holding portion 3 that holds the liquid, and the receiving portion 16d is connected by the narrow portion 16c. By providing the holding groove 16a, the sorting device 45 can increase the amount of liquid that can be held in the holding groove 16a, and by providing the guide groove 16b, the discharge path of the divided trace liquid can be stabilized. Can do. Here, the configuration of the ninth embodiment can also be applied to the fourth embodiment.

(Embodiment 10)
Next, a trace liquid sorting device and a sorting method according to Embodiment 10 will be described. FIG. 20 is a perspective view showing a sorting apparatus according to the tenth embodiment.

  As shown in FIG. 20, the sorting device 50 is configured to install an upper plate 51 on the solid substrate 2 of the sorting device 10 in the second embodiment. In the upper plate 51, a portion corresponding to the holding portion 3 is removed to form a holding opening 51a, and a portion corresponding to a guide groove that guides the movement of the trace amount liquid divided from the liquid is removed to form a passage 51b. Is formed. Therefore, when the sorting device 50 attaches the upper plate 51 to the solid substrate 2, the holding groove and the guide groove in the ninth embodiment are formed in the portion corresponding to the holding portion 3, and the same effect as the sorting device 45 is obtained. Can be demonstrated. Here, the upper plate 51 is made of, for example, a silicone rubber material using polymethylsiloxane (PDMS). At this time, the upper plate 51 is pasted on the solid substrate 2 using the self-adhesive property of PDMS.

  As described above, the trace liquid sorting apparatus and trace liquid sorting method according to the present invention are useful for accurately and quantitatively sorting a trace amount of liquid from a liquid mass exceeding the target liquid volume, Suitable for dispensing devices and analyzers.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a trace liquid sorting device for explaining Embodiment 1 according to a trace liquid sorting device and a trace liquid sorting method of the present invention. It is a top view which shows the shape of the holding | maintenance part holding the liquid in a trace amount liquid sorting device. It is a top view which shows the shape of the holding | maintenance part holding the liquid in a trace amount liquid sorting device. It is a top view which shows the shape of the holding | maintenance part holding the liquid in a trace amount liquid sorting device. It is a top view which shows the shape of the holding | maintenance part holding the liquid in a trace amount liquid sorting device. It is a front view which shows the shape of the liquid hold | maintained at the holding | maintenance part. It is a top view which shows a holding | maintenance part, a sound wave generation means, and the divided | segmented trace liquid. It is a front view which shows the liquid of the holding | maintenance part seen from the divided | segmented trace liquid side. It is sectional drawing which shows the propagation of the surface acoustic wave which the comb-tooth electrode generate | occur | produced. It is sectional drawing which shows the propagation of the surface acoustic wave in a fixed board | substrate, and the longitudinal wave sound wave in the liquid of a narrow part. It is the perspective view which expanded the narrow part. It is a top view which shows the modification of a trace amount liquid sorting device. It is a perspective view which shows the fractionation apparatus of Embodiment 2. It is a perspective view which shows the fractionation apparatus of Embodiment 3. It is sectional drawing of the fractionation apparatus cut | disconnected across the narrow part. It is a perspective view which shows the fractionation apparatus of Embodiment 4. It is a perspective view which shows the fractionation apparatus of Embodiment 5. It is a perspective view which shows the fractionation apparatus of Embodiment 6. It is a perspective view which shows the fractionation apparatus of Embodiment 7. FIG. 10 is a perspective view showing a sorting device according to an eighth embodiment. It is a figure which shows the shape of the slit provided in the holding wall. It is a figure which shows the shape of the opening provided in the holding wall. It is a perspective view which shows the fractionation apparatus of Embodiment 9. It is a perspective view which shows the fractionation apparatus of Embodiment 10. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sorting device 2 Solid substrate 3 Holding | maintenance part 3a Narrow part 3b Receiving part 3c Micro holding | maintenance part 4,5 Comb electrode 6 Wiring 7 Power supply 8 Electrode row 10,15 Sorting device 16,17 Solid substrate 18 Acoustic matching layer 20, 25 Preparative device 30, 35 Preparative device 40, 45 Preparative device 50 Preparative device 51 Upper plate Lq, Ln Liquid Lqm Trace liquid Ws Surface acoustic wave Wl Longitudinal wave acoustic wave Wt Transverse wave acoustic wave

Claims (18)

A holding part that is connected via the narrow part and holds the liquid;
A sound wave generating means for generating a sound wave from the direction intersecting the narrow part toward the narrow part,
And the holding part and the sound wave generating means are provided on the surface of a solid substrate.   2. The trace liquid dispensing apparatus according to claim 1, wherein the sound wave generating unit is provided on the first solid substrate together with the holding unit.   The trace liquid dispensing apparatus according to claim 2, wherein the sound wave generating unit and the holding unit are arranged on the same plane of the solid substrate.   2. The trace liquid dispensing apparatus according to claim 1, wherein the sound wave generating unit is provided on a second solid substrate different from the holding unit.   2. The trace liquid dispensing apparatus according to claim 1, wherein the sound wave generating unit generates a sound wave toward a liquid in the narrow portion from a direction orthogonal to the narrow portion.   The difference in acoustic impedance between the solid substrate and the liquid is smaller than the difference in acoustic impedance between the solid substrate and the atmosphere in contact with the solid substrate, and the difference in acoustic impedance between the liquid and the atmosphere in contact with the liquid. The trace liquid preparatory device according to claim 1, which is small.   2. The trace liquid dispensing apparatus according to claim 1, wherein the sound wave generation unit selectively directs the generated sound wave to a narrow portion of a droplet held by the holding unit.   The trace liquid sorting apparatus according to claim 1, wherein the sound wave generating unit is a surface acoustic wave generating unit configured to generate a surface acoustic wave.   The trace liquid sorting apparatus according to claim 7, wherein the surface acoustic wave generating means is a comb electrode in which linear electrodes are arranged on a plane.   The surface acoustic wave generating means is a comb-like electrode in which curved electrodes are arranged on a plane, and the surface acoustic wave is focused on an edge portion of the narrow portion liquid away from the surface acoustic wave generating means. The trace amount liquid preparatory device according to claim 7 characterized by things.   5. The trace liquid dispensing apparatus according to claim 4, wherein the first solid substrate and the second solid substrate are in close contact with each other through a substance having an acoustic impedance close to that of the liquid. The sound wave generating means is a surface acoustic wave generating means for generating a surface acoustic wave,
The substance having an acoustic impedance close to that of the liquid is based on the wavelength of the longitudinal wave generated by converting the surface acoustic wave as a sound source at the joint surface between the first solid substrate and the second solid substrate. The trace liquid preparatory apparatus according to claim 4, wherein the trace liquid is set to a predetermined thickness. The sound wave generating means is a surface acoustic wave generating means for generating a surface acoustic wave,
The first solid substrate is an acoustic impedance or liquid that can transmit longitudinal acoustic waves generated by converting the surface acoustic waves at the joint surface between the first solid substrate and the second solid substrate. The trace liquid preparatory device according to claim 4, wherein the liquid tracer is made of a material having an acoustic impedance close to. The sound wave generating means is a surface acoustic wave generating means for generating a surface acoustic wave,
The first solid substrate has a predetermined thickness on the basis of the wavelength of the longitudinal sound wave generated by converting the surface acoustic wave at the joint surface between the first solid substrate and the second solid substrate. It is set, The trace liquid preparatory device of Claim 4 characterized by the above-mentioned.   The width of the liquid in the narrow part when the liquid is held in the holding part is a predetermined value determined by a wavelength of a longitudinal wave sound wave using the surface acoustic wave as a sound source. Trace liquid fractionator.   2. The trace liquid dispensing apparatus according to claim 1, wherein a surface of the holding part has hydrophilicity, and a surface of a portion adjacent to the holding part has hydrophobicity.   The first solid substrate is arranged so as to be lowered from the sound wave generating means side toward the holding portion side and inclined at an angle at which the liquid is held by the holding portion. 2. The trace liquid fractionator according to 1. A liquid separation method for separating a liquid formed on a solid substrate and held by a holding unit connected via a narrow portion by sound waves,
Emitting sound waves from the direction intersecting the narrow portion toward the narrow portion;
Separating a trace amount of liquid from the liquid by acoustic radiation pressure of the acoustic wave;
A method for fractionating a trace amount of liquid, comprising:

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