Droplet ejection method, method for manufacturing container containing tissue body, and droplet ejection device

Abstract

To improve the accuracy of the placement of liquid droplets.SOLUTION: A liquid droplet discharging method is implemented by a liquid droplet discharging apparatus configured to discharge a liquid droplet from a nozzle hole formed in a film-like member, and includes a positioning step for positioning the nozzle hole inside a recessed portion provided in a container, and a discharging step for discharging the liquid droplet from the nozzle hole positioned inside the recessed portion.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present application relates to a droplet ejection method, a method for manufacturing a tissue-containing container, and a droplet ejection device. [Background technology]

[0002] In recent years, advances in stem cell technology have led to the development of techniques for placing tissues containing multiple cells in desired locations. For example, in fields such as drug discovery and toxicity assessment, assays to confirm the response of cells to drugs are performed using well plates (containers) with multiple wells (concave holes), and techniques have been developed to place tissues in well plates and reproduce phenomena occurring in the human body within the well plates.

[0003] As a method for positioning such tissues at desired positions, a configuration has been disclosed in which a membrane-like member having nozzle holes formed therein is vibrated to eject droplets containing a cell suspension or the like (see, for example, Patent Document 1). Summary of the Invention [Problem to be solved by the invention]

[0004] However, the configuration of Patent Document 1 leaves room for improvement in the accuracy of droplet placement.

[0005] An object of the present invention is to improve the accuracy of droplet placement. [Means for solving the problem]

[0006] A droplet discharge method according to one aspect of the present invention is a droplet discharge method using a droplet discharge device that discharges droplets from nozzle holes formed in a film-like member, and includes a disposing step of disposing the nozzle holes inside a recess provided in a container, and a discharging step of discharging the droplets from the nozzle holes disposed inside the recess. In the arranging step, a vibrating unit including the film member, a support member that supports the film member, and a vibrating unit that vibrates the film member is arranged inside the recess. . [Effects of the Invention]

[0007] According to the present invention, the accuracy of droplet placement can be improved. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram showing an example of the overall configuration of a droplet ejection device according to a first embodiment. [Figure 2] 1 is a diagram illustrating an example of the configuration of a MEMS chip according to a first embodiment. [Figure 3A] 10A and 10B are diagrams illustrating examples of connections between the lower electrodes of the piezoelectric elements and wiring. [Figure 3B] 10A and 10B are diagrams illustrating examples of connections between the upper electrodes of the piezoelectric elements and wiring. [Figure 4] 2 is a view of the MEMS chip according to the first embodiment as viewed from the droplet ejection direction. FIG. [Figure 5] 1 is a view of a discharge head according to a first embodiment, viewed from the direction in which droplets are discharged. [Figure 6] FIG. 10 is a view of a MEMS chip according to a modified example, viewed from the droplet ejection direction. [Figure 7] FIG. 10 is a diagram illustrating an example of a driving waveform. [Figure 8] 1A to 1C are diagrams illustrating an example of a process in which droplets are formed. [Figure 9] FIG. 4 is a diagram showing a first example of a drive waveform applied to a piezoelectric element. [Figure 10] FIG. 10 is a diagram showing a second example of a drive waveform applied to a piezoelectric element. [Figure 11] FIG. 10 is a diagram showing a third example of a drive waveform applied to a piezoelectric element. [Figure 12] FIG. 10 is a diagram showing an example of the overall configuration of a droplet ejection device according to a second embodiment. [Figure 13] FIG. 3 is a diagram illustrating an example of a current generated in a piezoelectric element. [Figure 14] FIG. 10 is a block diagram showing an example of the functional configuration of a control unit according to a second embodiment. [Figure 15] 10 is a flowchart showing an example of the operation of the droplet ejection device according to the second embodiment. [Figure 16] FIG. 10 is a diagram illustrating a configuration example of a MEMS chip according to a third embodiment. [Figure 17] FIG. 11 is a block diagram showing an example of the functional configuration of a control unit according to the third embodiment. [Figure 18] 10 is a flowchart showing an example of the operation of the droplet ejection device according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following describes the preferred embodiments of the present invention with reference to the accompanying drawings. In the drawings, the same components are designated by the same reference numerals, and redundant explanations will be omitted where appropriate.

[0010] A droplet ejection method according to an embodiment is a droplet ejection method using a droplet ejection device that ejects droplets from nozzle holes formed in a film-like member. In the embodiment, the nozzle holes formed in the film-like member are arranged inside a recess provided in a container, and droplets are ejected from the nozzle holes arranged inside the recess. This improves the accuracy of droplet placement inside the recess compared to when droplets are ejected from outside the recess.

[0011] In the figures shown below, directions may be indicated by the X-axis, Y-axis, and Z-axis. The X-direction along the X-axis indicates a specific direction within an array plane in which multiple wells (recesses) in a well plate (container) are arranged, the Y-direction along the Y-axis indicates a direction perpendicular to the X-direction within the array plane, and the Z-direction along the Z-axis indicates a direction perpendicular to the array plane.

[0012] Furthermore, the direction in which the arrow points in the X direction is denoted as the +X direction, and the direction opposite to the +X direction is denoted as the -X direction, the direction in which the arrow points in the Y direction is denoted as the +Y direction, and the direction opposite to the +Y direction is denoted as the -Y direction, and the direction in which the arrow points in the Z direction is denoted as the +Z direction, and the direction opposite to the +Z direction is denoted as the -Z direction. In the embodiment, as an example, the ejection head ejects droplets in the -Z direction.

[0013] [First embodiment] <Example of Overall Configuration of Droplet Discharge Device 100> First, the overall configuration of a droplet ejection device 100 will be described with reference to Fig. 1. Fig. 1 is a diagram illustrating an example of the overall configuration of the droplet ejection device 100.

[0014] As shown in FIG. 1, the droplet ejection device 100 includes an ejection head 1, a control unit 4, and a head actuator 9.

[0015] The droplet discharge device 100 has one end of the discharge head 1 inserted into wells 51, which are a number of well-shaped holes formed in a well plate 5, which is a flat member. The well plate 5 is an example of a container, and is an example of a container containing tissue. The wells 51 are an example of a recess.

[0016] The well plate 5 has a plurality of wells 51 arranged in a two-dimensional array in the array plane. The wells 51 are preferably substantially cylindrical in shape with flat bottoms 52, but may be non-cylindrical, such as substantially square pillars, or may have sloped side walls or sloped bottoms 52.

[0017] In the embodiment, a well plate 5 is exemplified, but the container may be in the form of a plate or a slide glass, or in the form of a tube. Also, although a configuration in which the container has multiple wells 51 is exemplified, the container may have only one well 51.

[0018] The ejection head 1 is provided with a MEMS (Micro Electro Mechanical System) chip 6 at the end inserted into the well 51. The ejection head 1 also has a nozzle hole 621 in the MEMS chip 6. A drive waveform generating source 7 applies a drive waveform (drive voltage) to the MEMS chip 6 via wiring 71 and 72, causing the ejection head 1 to eject the liquid held in the MEMS chip 6 from the nozzle hole 621 into the well 51 as droplets D.

[0019] The control unit 4 is a control device that controls the overall operation of the droplet ejection device 100. For example, the control unit 4 can control the application of a drive waveform to the ejection head 1 by the drive waveform generation source 7, and the positioning operation of the nozzle holes 621 by the head actuator 9.

[0020] The head actuator 9 has a holder that holds the discharge head 1 and a movement mechanism that moves back and forth in three axial directions, the X-axis, the Y-axis, and the Z-axis, and is an example of an arrangement unit that changes the position of the discharge head 1 held by the holder to arrange the nozzle holes 621 inside the wells 51 of the well plate 5. The head actuator 9 may further have a rotation mechanism that allows the attitude of the nozzle holes 621 to be changed.

[0021] From the viewpoint of the accuracy of placement of droplets D in wells 51, the droplet discharge device 100 preferably arranges the nozzle holes 621 within a height range of 0.5 to 3.0 mm from the bottom 52 of the wells 51. Furthermore, since the height of each well 51 in a 96-well well plate 5, which is a suitable well plate 5, is approximately 12 mm, it is preferable to arrange the nozzle holes 621 at a depth that is 70% or more of the depth of the wells 51.

[0022] For example, if a nozzle hole is located outside the well and droplets are ejected, the distance from the bottom of the well is long, which can result in poor droplet placement accuracy within the well. Similarly, if a nozzle hole is located a few percent deep from the open side of the well (the opposite side of the bottom in the Z direction) and droplets are ejected, the distance from the bottom of the well is long, which can also result in poor droplet placement accuracy. Furthermore, the long distance from the bottom of the well can cause some of the ejected liquid to scatter, making it impossible to obtain the desired droplet shape.

[0023] In contrast, the droplet discharge device 100 discharging droplets D from a nozzle hole 621 disposed inside the well 51, and therefore can discharge droplets D at a short distance from the bottom 52 of the well 51. This improves the accuracy of disposing droplets D within the well 51. Furthermore, discharging droplets D at a short distance from the bottom 52 can prevent some of the discharged liquid from scattering.

[0024] Furthermore, it is preferable that the discharge head 1 is configured so as not to interfere with the wall surface of the well 51, in order to bring the nozzle hole 621 close to the bottom 52 of the well 51. For this reason, it is conceivable to configure the discharge head to include a thin tube such as a needle or tube, and to place the nozzle hole provided in the thin tube inside the well 51. However, this has many disadvantages and is difficult to adopt when discharging a cell suspension, particles, etc.

[0025] More specifically, when a fluid such as a cell suspension or particles is ejected from a nozzle hole through a capillary tube, the resistance to the fluid generally increases, significantly reducing the ejection force and making it impossible to eject the fluid as intended. Furthermore, since particles such as cells tend to clog the capillary tube, it is difficult to maintain a fluid flow path within the capillary tube. Furthermore, the inside of the capillary tube is prone to strong pressure and shear stress, increasing the risk of cell death.

[0026] <Configuration example of ejection head 1> Next, the configuration of the discharge head 1 will be described with reference to Fig. 2. Fig. 2 is a diagram illustrating an example of the configuration of the discharge head 1, and is an enlarged view of the vicinity of the portion P indicated by the dashed line in Fig. 1. As shown in Fig. 2, the discharge head 1 includes a chamber 61 and wiring 71.

[0027] Chamber 61 is an example of a liquid chamber that holds liquid 200, and includes an air-opening portion 611, a liquid chamber member 612, an elastic member 613, and a MEMS chip 6. Fig. 2 illustrates a state in which chamber 61 holds liquid 200, which is a particle suspension in which sedimentable particles 250 are suspended (dispersed). Sedimentable particles 250 may be metal particles, inorganic particles, or cells, particularly human cells.

[0028] The size of the chamber 61 and the amount of the liquid 200 that can be accommodated in the chamber 61 are not particularly limited and can be appropriately selected depending on the purpose. The amount of the liquid 200 can be, for example, 1 μL to 1 mL, and if the liquid 200 is a cell suspension or the like in which cells are dispersed, it can also be 1 μL to 50 μL. However, the amount of the liquid 200 is controlled and changed by the control unit 4 as a factor that contributes to the vibration characteristics of the membrane 62. The liquid amount E shown in FIG. 2 represents the amount of the liquid 200 filled in the chamber 61.

[0029] The atmosphere vent portion 611 is a portion that opens the inside of the chamber 61 to the atmosphere. The chamber 61 has the atmosphere vent portion 611 on the +Z direction side of the chamber 61. Air bubbles mixed in the liquid 200 can be discharged from the atmosphere vent portion 611.

[0030] The MEMS chip 6 is a device fabricated by microfabricating a silicon substrate using a semiconductor process that uses photolithography, and is an example of a vibration part that integrates a membrane 62, a piezoelectric element 63, and a membrane support part 65.

[0031] The MEMS chip 6 is joined to an end of the liquid chamber member 612 along the direction in which the droplets D are ejected (the -Z direction in FIG. 2). The chamber 61 holds the liquid 200 in a space formed by joining the liquid chamber member 612 and the MEMS chip 6 via an elastic member 613.

[0032] The outer shape of the MEMS chip 6 is preferably similar to the shape of the bottom 52 of the well 51 so that a larger tissue model can be placed at the bottom 52 of the well 51. For example, since the bottom 52 of the well 51 in a typical 96-well well plate 5 is circular, it is preferable that the MEMS chip 6 also be circular.

[0033] However, since it is generally difficult to process an object into a circular shape in semiconductor processes, polygonal shapes such as squares, hexagons, and octagons can also be formed. It is preferable to form a polygonal shape that is as close to a circle as possible within the limits of what can be processed. Furthermore, since the shape of the bottom 52 of the well 51 can be roughly square, the external shape of the MEMS chip 6 can be changed as needed depending on the shape of the bottom 52.

[0034] The substrate of the MEMS chip 6 is not limited to silicon, and other materials such as glass can also be used. Furthermore, the method for manufacturing the piezoelectric element 63 is not limited to the semiconductor process, and processes other than the semiconductor process, such as a process of patterning a piezoelectric precursor liquid by an inkjet method, can also be used.

[0035] The membrane 62 is an example of a film-like member that is fixed to the end of the chamber 61 on the -Z direction side and is integrally formed with the membrane support part 65 of the MEMS chip 6. The membrane 62 has a nozzle hole 621, which is a through-hole, approximately at the center of the membrane 62. The membrane support part 65 is an example of a support member that supports the membrane 62.

[0036] The ejection head 1 ejects the liquid 200 held in the chamber 61 as droplets D from the nozzle holes 621 by vibrating the membrane 62. The shape of the planar portion of the membrane 62 is, for example, circular, but it may also be elliptical, rectangular, or other shapes. In addition, it is preferable that the shape of the planar portion of the membrane 62 is approximately similar to the shape of the bonding surface with the liquid chamber member 612.

[0037] Furthermore, if membrane dimension A from the nozzle hole 621 to the outer edge of the membrane 62 is larger than liquid chamber member dimension B from the nozzle hole 621 to the inner edge of the liquid chamber member 612, air will be more likely to remain in the protruding portion of the liquid chamber member 612. This may impair the ejection function, so it is preferable that membrane dimension A be smaller than liquid chamber member dimension B.

[0038] The nozzle hole 621 is preferably formed as a circular through-hole approximately in the center of the membrane 62, but may also have a polygonal planar shape. If the nozzle hole 621 is circular, the diameter of the nozzle hole 621 is not particularly limited, but is preferably at least twice the size of the sedimentable particles 250 in order to prevent the sedimentable particles 250 from clogging the nozzle hole 621 and to stably discharge the droplets D. Specifically, since the size of animal cells, particularly human cells, is generally about 5 μm to 50 μm, the diameter of the nozzle hole 621 is preferably 10 μm to 100 μm or more to match the size of the cells to be used.

[0039] On the other hand, if the droplets D become too large, it becomes difficult to achieve the purpose of forming minute droplets D, so the diameter of the nozzle holes 621 is preferably 200 μm or less. Therefore, in the droplet ejection device 100, the diameter of the nozzle holes 621 is typically in the range of 10 μm to 200 μm.

[0040] The piezoelectric element 63 is an example of a vibrating section that vibrates the membrane 62, and is formed integrally with the MEMS chip on the underside of the membrane 62. The shape of the piezoelectric element 63 can be designed to match the shape of the membrane 62. For example, if the planar shape of the membrane 62 is circular, it is preferable to form the piezoelectric element 63 having an annular (ring-shaped) planar shape around the nozzle hole 621.

[0041] Furthermore, the piezoelectric element 63 includes a piezoelectric body 631, a lower electrode 632 provided on the upper surface (surface on the -Z direction side) of the piezoelectric body 631, and an upper electrode 633 provided on the lower surface (surface on the +Z direction side) of the piezoelectric body 631. The lower electrode 632 and the upper electrode 633 are examples of a plurality of electrodes, and each of the lower electrode 632 and the upper electrode 633 is an example of an electrode.

[0042] Applying a drive waveform to the lower electrode 632 or upper electrode 633 of the piezoelectric element 63 causes it to contract in the X direction, applying compressive stress and vibrating the membrane 62 in the Z direction. Lead zirconate titanate, for example, can be used as the piezoelectric material. Other materials that can be used include bismuth iron oxide, metal niobate, barium titanate, or any of these materials to which a metal or a different oxide has been added.

[0043] One end of the wiring 71 is connected to a wiring connection portion 712 of the MEMS chip 6 via a conductive adhesive 711. The wiring 71 is also drawn out to the outer surface side of the liquid chamber member 612 and arranged along the outer surface, and the other end is connected to the drive waveform generating source 7.

[0044] The piezoelectric element 63 vibrates the membrane 62 in response to voltages applied to the lower electrode 632 and the upper electrode 633 through wiring 71 connected via a conductive adhesive 711. Here, the conductive adhesive 711 is a conductive adhesive made of an epoxy resin-based material or the like mixed with a conductive filler.

[0045] Common wire bonding or the like can be applied to connect the wiring 71 and the MEMS chip 6. However, in this case, a protrusion of the mounting portion occurs in the discharge direction of the droplet D, which may come into contact with the droplet D placed on the bottom 52 of the well 51. Therefore, it is preferable to minimize the height by pressing with a conductive adhesive 711. Note that the mounting method is not limited to wire bonding, and other methods may be used as long as the wiring is stably connected. Furthermore, while only the wiring 71 is illustrated in FIG. 2, the wiring 72 shown in FIG. 1 can also be configured and connected in the same manner as the wiring 71.

[0046] The wiring 71 is fixed to the outer surface of the liquid chamber member 612 using adhesive, double-sided tape, or the like. However, if the wiring 71 protrudes from the outer surface of the liquid chamber member 612, when the nozzle hole 621 is placed inside the well, the ejection head may collide with the inner wall of the well, which may restrict the placement of the droplets D containing the tissue. For this reason, it is preferable to form a groove for accommodating the wiring 71 on the outer surface of the liquid chamber member 612, and to affix the wiring 71 to the liquid chamber member 612 so that the wiring 71 is accommodated inside the groove.

[0047] It is preferable that the wires 71 are as thin as possible and that the material of the wires 71 is easy to wire. For example, it is preferable to prepare a flat conductor with an insulating coating and connect it by stripping off the coating only at the ends.

[0048] The elastic member 613 is a member that includes an elastic body that transmits as little vibration generated by driving the MEMS chip 6 as possible to the liquid chamber member 612. The elastic member 613 also has the function of bonding the liquid chamber member 612 and the MEMS chip 6. For example, such an elastic member 613 can be formed by an adhesive that bonds the MEMS chip 6 and the liquid chamber member 612. However, even if the elastic member 613 is made of a hard material or if the liquid chamber member 612 and the MEMS chip 6 are directly bonded without the elastic member 613, the main function of the ejection head 1 can be achieved, so the elastic member 613 is not necessarily provided.

[0049] The outer shape of the portion of the liquid chamber member 612 that is inserted into the well is preferably approximately similar to the shape of the bottom 52 of the well 51, so that droplets D are placed on the bottom 52 of the well 51, and this configuration maximizes the range of motion of the ejection head 1. For example, in the case of a 96-well well plate, the bottom 52 of the well 51 generally has a diameter of about 6 mm, so it is preferable that the outer shape of the portion of the liquid chamber member 612 that is inserted into the well be circular and have a diameter of about 3 to 5 mm.

[0050] The shape of the liquid chamber member 612 that is not inserted into the well 51 is appropriately added to a cylindrical shape in accordance with the shape of the holding portion of the liquid chamber.

[0051] The material for the liquid chamber member 612 is preferably one that has low cytotoxicity, heat resistance, and good processability. Examples include polyetheretherketone (PEEK), which is a so-called engineering plastic, or polycarbonate (PC). However, other plastics, metals, ceramics, and other materials can also be used. Regarding heat resistance, it is easier to use if the material can withstand autoclave processing (high pressure, 120°C) for sterilization, but this is not essential as other methods such as ethanol and UV irradiation are also available.

[0052] The drive waveform generating source 7 is a signal generator that outputs a drive waveform as a drive signal to the piezoelectric element 63. By outputting the drive waveform to the piezoelectric element 63, the drive waveform generating source 7 can deform the membrane 62 and eject the liquid 200 contained in the chamber 61 as droplets D. In addition, by deforming the membrane 62 with a drive waveform set at a predetermined cycle, it is possible to cause the membrane 62 to vibrate resonantly and eject the liquid.

[0053] The MEMS chip 6 is preferably installed downstream (-Z direction) of the discharge direction relative to the liquid chamber member 612. In addition to placing the cell suspension, the tissue placement process may also benefit from adding a liquid or gel that constitutes a living organism, or a biocompatible liquid or gel, before or after cell placement. This contributes to factors such as the adhesion of the cells to the bottom of the well, cell survival rate, and cell maturity.

[0054] 3A is a cross-sectional view illustrating an example of the connection between the lower electrode 632 of the piezoelectric element 63 in the MEMS chip 6 and the wiring 71. Also, Fig. 3B is a cross-sectional view illustrating an example of the connection between the upper electrode 633 of the piezoelectric element 63 in the MEMS chip 6 and the wiring 71. Figs. 3A and 3B each show a cross-sectional structure perpendicular to the Y direction of region Q indicated by the dashed line in Fig. 2.

[0055] 3A, the MEMS chip 6 has a lower electrode wiring 714a on the −Z direction side of the membrane support part 65, with an interlayer insulating film 715 sandwiched therebetween. The lower electrode wiring 714a is connected to the lower electrode 632 via a lower electrode connecting part 713a. The MEMS chip 6 also has an insulating film 716 on the −Z direction side of the lower electrode wiring 714a. The part from which the insulating film 716 has been removed corresponds to a lower wiring connecting part 712a that connects the wiring 71 and the lower electrode 632.

[0056] 3B, the MEMS chip 6 has upper electrode wiring 714b on the -Z direction side of the membrane support portion 65, with an interlayer insulating film 715 sandwiched therebetween. The upper electrode wiring 714b is connected to the upper electrode 633 via an upper electrode connecting portion 713b. The MEMS chip 6 also has an insulating film 716 on the -Z direction side of the upper electrode wiring 714b. The portion from which the insulating film 716 has been removed corresponds to an upper wiring connecting portion 712b that connects the wiring 72 and the upper electrode 633.

[0057] However, these connections are merely examples, and the lower wiring connection portion 712a and the upper wiring connection portion 712b may be provided on any of the surfaces that constitute the MEMS chip 6 by other methods.

[0058] Next, Fig. 4 is a view of the MEMS chip 6 viewed from the direction of droplet ejection, and Fig. 5 is a view of the ejection head 1 viewed from the direction of droplet ejection. As shown in Figs. 4 and 5, the membrane 62 has an octagonal outer shape, and the liquid chamber member 612 has a circular outer shape.

[0059] 4, the wiring 71 is connected to the lower electrode via a lower electrode connection portion 713a and a lower wiring connection portion 712a, and the wiring 72 is connected to the upper electrode via an upper electrode connection portion 713b and an upper wiring connection portion 712b.

[0060] 5, the liquid chamber member 612 has a lower electrode groove 612a and an upper electrode groove 612b on the outer surface 610 of the liquid chamber member 612. The lower electrode groove 612a is an example of an accommodating portion that accommodates the wiring 71 connected to the lower electrode, and the upper electrode groove 612b is an example of an accommodating portion that accommodates the wiring 72 connected to the upper electrode.

[0061] The lower electrode groove 612a is a groove with a U-shaped cross section formed on the outer surface of the liquid chamber member 612 with a width and depth that allows the wiring 71 to be accommodated and fixed so that the wiring 71 does not protrude from the outer surface of the liquid chamber member 612. Similarly, the upper electrode groove 612b is a groove with a U-shaped cross section formed on the outer surface of the liquid chamber member 612 with a width and depth that allows the wiring 72 to be accommodated and fixed so that the wiring 72 does not protrude from the outer surface of the liquid chamber member 612. However, the accommodation portion is not limited to a U-shaped groove as long as it can accommodate the wiring 71 or 72 therein, and may have any cross section, or may have a configuration in which the width or depth varies partially.

[0062] 6 is a view of a MEMS chip 6A according to a modified example of the MEMS chip 6, viewed from the droplet ejection direction. As shown in Fig. 6, the MEMS chip 6A has two piezoelectric elements, 63a and 63b. For example, one of the piezoelectric elements 63a and 63b functions as a vibrating unit that vibrates the membrane 62, and the other functions as a detecting unit that detects the back electromotive force generated by the vibrating unit.

[0063] Of the piezoelectric element 63a and the piezoelectric element 63b, one that functions as a vibrating portion is an example of a first piezoelectric element, and the other that functions as a detecting portion is an example of a second piezoelectric element. The ejection head 1 can also be configured using such a MEMS chip 6A.

[0064] <Example of droplet ejection process by droplet ejection device 100> Next, the droplet discharge process by the droplet discharge device 100 will be described with reference to Figs. 7 and 8, which show simplified configurations. Fig. 7 is a diagram illustrating an example of a drive waveform. Fig. 8 is a diagram illustrating an example of the process by which droplets are formed, and shows a part of the droplet discharge device 100 (see Fig. 1).

[0065] When the waveform element P1 and waveform element P2 shown in Fig. 7 are output to the piezoelectric element 63, the state of the liquid in the chamber 61 changes and a droplet D is formed, as shown in states 81 to 83 in Fig. 8. The waveform element refers to the waveform during the period when the voltage change in the drive waveform is inclined.

[0066] Specifically, when waveform element P1 is output, the piezoelectric element 63 contracts in the X direction in Figure 8, causing the membrane 62 near the nozzle hole 621 to suddenly deform so as to recess in the +Z direction as shown in state 81, and in response to this deformation, the liquid 200 contained in the chamber 61 is pushed out from the nozzle hole 621 in the -Z direction.

[0067] Thereafter, as shown in state 82, a liquid column protruding from the nozzle hole 621 in the -Z direction grows, and as shown in state 83, a droplet D is formed and ejected along the -Z direction. The droplet D is formed at a predetermined timing, regardless of the timing of the residual vibration suppression by the waveform element P2.

[0068] <Examples of various drive waveforms> Next, various drive waveforms will be described with reference to Figures 9 to 11. Figures 1 and 2 will also be referenced as appropriate.

[0069] 9 is a diagram illustrating a first example of a drive waveform applied to a piezoelectric element. In FIG. 9, when waveform element P1 is applied to piezoelectric element 63, membrane 62 deforms upward (toward the +Z direction in FIG. 7). Thereafter, waveform element P2 is applied to piezoelectric element 63 at a timing corresponding to time difference T12 in the drive waveform.

[0070] Here, the term "time difference in the drive waveform" in the embodiment refers to the time difference from the start timing of application of a predetermined waveform element to the end timing of the period during which a constant voltage value is maintained after the application of the waveform element has ended. Therefore, the time difference T12 is the time difference from the start timing of application of waveform element P1 to the end timing of the period during which a constant voltage value is maintained after the application of waveform element P1 has ended. Such time difference T12 is a characteristic value determined by the design of the drive waveform, and is an example of a "predetermined time difference."

[0071] When the waveform element P2 is applied to the piezoelectric element 63, if the resonance period of the membrane 62 is T0, the waveform element P2 is applied to the piezoelectric element 63 after the resonance period T0 has elapsed since the membrane 62 began to vibrate due to the waveform element P1. The pressure generated by the deformation of the membrane 62 due to the waveform element P2 acts in a direction that suppresses the vibration of the membrane 62 caused by the waveform element P1. .

[0072] In other words, when the condition of the following formula (1) is satisfied, the waveform element P2 acts in a direction that suppresses the residual vibration of the membrane 62. T12=m×T0 (m: positive integer) (1)

[0073] In this case, if the time required for waveform element P1 and waveform element P2 are made equal, it becomes easier to balance ejection and suppression of residual vibration. Furthermore, the more the resonance period T0 of membrane 62 and the time difference T12 in the drive waveform deviate from the condition of equation (1), the more difficult it becomes to achieve stable ejection, so it is preferable to adjust the resonance period T0 or the time difference T12 in the drive waveform so that the condition of equation (1) is satisfied.

[0074] In this embodiment, the control unit 4 controls the liquid volume E of the liquid 200 in the well 51 to align the resonance period T0 with the time difference T12 in the drive waveform. However, this is not limited to this, and the resonance period T0 can also be aligned with the time difference T12 in the periods of the drive waveform by other methods, such as controlling the height of an adjustment member placed above the nozzle hole 621 (on the +Z direction side in FIG. 7).

[0075] Next, FIG. 10 is a diagram illustrating a second example of the drive waveform.

[0076] As shown in Figure 10, when a predetermined voltage is applied to the piezoelectric element 63 in advance, causing the membrane 62 to deform upward, and then the membrane 62 is returned downward by the waveform element P1, the liquid surface (meniscus) in the nozzle hole 621 shifts upward once and then vibrates freely.

[0077] Thereafter, after maintaining a constant voltage, waveform element P2 is applied with a timing of time difference T12. At this time, by applying waveform element P2 after a period of 1 / 2 the resonance period T0 from when the membrane 62 starts to vibrate due to waveform element P1, the membrane 62 shifts upward in synchronization with the vibration caused by waveform element P1. As a result, the force of shifting the membrane 62 upward due to free vibration and the force of shifting the membrane 62 upward due to waveform element P2 combine to increase the force of droplet ejection.

[0078] Considering that the waveform element P1 has a certain period, the condition of the following equation (2) is satisfied. In this case, the waveform element P2 acts in a direction that increases the force of ejection. T12=(m-1 / 2)×T0 (m: positive integer) (2) By doing so, it becomes possible to eject droplets even with a low voltage.

[0079] Next, FIG. 11 is a diagram illustrating a third example of the drive waveform.

[0080] As shown in Figure 11, when a predetermined voltage is applied to the piezoelectric element 63 in advance, causing the membrane 62 to deform upward, and then the membrane 62 is returned downward by the waveform element P1, the liquid level in the nozzle hole 621 shifts upward once and then vibrates freely.

[0081] After that, a constant voltage is maintained, and then waveform element P2 is applied with a time difference of T12. After that, a constant voltage is maintained again, and then waveform element P3 is applied with a time difference of T23. The time difference T23 is the time difference from the start of application of waveform element P2 to the end of the period during which a constant voltage value is maintained after application of waveform element P2 has ended.

[0082] In this case, if the conditions of the following expressions (3) and (4) are satisfied, the waveform elements P2 and P3 act in a direction that suppresses the residual vibration of the membrane 62. T12=(m-1 / 2)×T0 (m: positive integer) (3) T23=n×T0 (n: positive integer) (4)

[0083] In this way, matching the resonance period T0 of the membrane 62 with the time difference in the drive waveform such as the time difference T12 or T23 is important for stable ejection and highly efficient ejection at a low voltage.

[0084] <Effects of the droplet ejection device 100> Next, the effects of the droplet ejection device 100 will be described.

[0085] In recent years, advances in stem cell technology have led to the development of technologies for placing tissues containing multiple cells in any desired location. In particular, in fields such as drug discovery and toxicity assessment, well plates, which have multiple wells, are commonly used to conduct assays to confirm the response of cells to drugs. There is a growing demand for forming tissues within these well plates to reproduce the phenomena that occur in the human body.

[0086] The construction of such assays not only shortens the time and cost required for screening candidate drugs, but also has other advantages, such as eliminating inefficient development caused by differences in drug response between animals and humans, and reducing the need for animal testing.

[0087] There are many different types of well plates, but they all have roughly the same external dimensions. The most common configurations are 6 (6 wells), 12 (12 wells), 24 (24 wells), 48 (48 wells), 96 (96 wells), and 384 (384 wells). The more wells there are, the smaller the individual wells become. For assay systems, a plate with a large number of wells is preferable, and plates with 96 or more wells are often used. Furthermore, if the wells are too small, it becomes difficult to form tissues within the wells, so a 96-well plate is preferred.

[0088] In addition, a device that ejects droplets by vibrating a film-like member having nozzle holes formed therein is disclosed, which acquires information used to control the resonance frequency of the film-like member in order to stably eject small amounts of liquid.Means for forming tissues in well plates include extrusion, photolithography, and inkjet (droplet ejection) methods.

[0089] The extrusion method involves extruding a gel containing dispersed cells from a dispenser, but the placement resolution depends on the size of the dispenser needle, making it unsuitable for forming tissue structures that require precise placement, with a resolution limit of around a few hundred microns.

[0090] In addition, the stereolithography method involves dispersing cells, preparing a gel precursor in a well, and then hardening it using an optical probe to create a model. However, when dealing with multiple types of cells, it is necessary to first wash the well containing the cells, which inevitably damages the cells.

[0091] In contrast, the inkjet method performs non-contact ejection with a high resolution of several tens of micrometers, making it the most suitable method for forming tissue structures within wells.

[0092] As a method for ejecting cells using an inkjet method, a configuration has been disclosed in which a cell suspension or the like is ejected using a device that ejects droplets by vibrating a membrane-like member having nozzle holes formed therein (see, for example, Patent Document 1).

[0093] Also, a configuration has been disclosed that realizes a droplet dispensing device with precise liquid volume by applying MEMS technology to a method of discharging cells using an inkjet method (see, for example, Japanese Patent No. 4788408). Furthermore, a technology has been disclosed that uses an inkjet method to roughly arrange cells in a well plate (see, for example, http: / / inventia.life / ).

[0094] However, in conventional techniques, droplets containing tissues are ejected from outside the wells of a well plate, and the long flight distance from the nozzle hole to the impact point makes it difficult to position the droplets with the desired accuracy, which can lead to reduced accuracy in the placement of the tissues. Furthermore, the increased droplet speed can cause scattering after impact and the generation of unintended tiny droplets called satellite droplets, which can interfere with the intended placement and reduce the accuracy of droplet placement, which can lead to reduced accuracy in the placement of the tissues.

[0095] In this embodiment, a nozzle hole formed in a film-like member (membrane 62) is disposed inside a recess provided in a container (well plate 5) (disposing step), and droplets are ejected from the nozzle hole disposed inside the recess (discharging step). For example, the nozzle hole is disposed at a depth of 70% or more of the depth of the recess, and droplets are ejected from the nozzle hole.

[0096] Since droplets can be ejected from a short distance from the bottom of the recess and the tissue contained in the droplets can be placed at the bottom of the recess, the accuracy of placing the droplets inside the recess can be improved compared to when droplets are ejected from outside the recess, and the accuracy of placing the tissue contained in the droplets can be improved.

[0097] In this embodiment, the membrane 62, which has the nozzle hole formed therein, is also disposed inside the recess (well 51). This reduces the areas that create fluid resistance, allowing for discharge without impairing the discharge force. Furthermore, when discharging live cells, there is a high risk of the live cells dying due to the action of pressure when the tip of a capillary or the like has a narrow shape, but the configuration of this embodiment can reduce this risk of death.

[0098] In addition, in this embodiment, in the placement process by the placement unit (head actuator 9), a vibration unit (MEMS chip 6) including a film-like member (membrane 62), a support member (membrane support unit 65) that supports the film-like member, and a vibration unit (piezoelectric element 63) that vibrates the film-like member is placed inside the recess (well 51).

[0099] This allows the vibration section to penetrate deep into the well, allowing stirring to occur right up until the liquid is discharged from the nozzle hole, preventing particles such as cells from clogging the nozzle hole.

[0100] In this embodiment, the droplet contains a material that constitutes a living body or a biocompatible material, which allows the material that constitutes a living body or a biocompatible material to be accurately disposed in the recess.

[0101] In this embodiment, the droplets are a cell suspension containing cells, which allows the cells to be placed in the wells with high precision.

[0102] In this embodiment, when the outer shape of the flat surface of the recess and the outer shape of the flat surface of the film-like member are both circular, the diameter of the film-like member is smaller than the diameter of the flat surface of the recess, which makes it possible to bring the film-like member closer to the bottom surface of the recess having the flat surface, and to eject droplets from the nozzle holes formed in the film-like member.

[0103] In addition, in this embodiment, the ejection head has a vibration part that integrates a membrane-like member including a nozzle hole, a support member that supports the membrane-like member, and a vibration part that is arranged on a part of the membrane-like member and a part of the support member, and also has a liquid chamber member that is joined to the vibration part and holds liquid.

[0104] For example, the vibration unit is a component integrally molded using a semiconductor process and is joined to the end of the liquid chamber member along the direction in which the droplets are ejected. This configuration allows the end of the ejection head to be made smaller, and droplets can be ejected with the nozzle hole provided at the end of the ejection head inserted inside the recess.

[0105] In this embodiment, the vibration unit is joined to the liquid chamber member via an elastic member, which allows droplets to be ejected with minimal transmission of vibrations generated by driving the vibration unit to the liquid chamber member and the ejection head, thereby minimizing droplet placement errors caused by the vibrations of the ejection head.

[0106] Furthermore, in this embodiment, when the outer shape of the flat portion of the film-like member is circular and the liquid chamber member is a cylindrical member, the inner diameter of the end of the liquid chamber member on the side where the elastic member is arranged (twice the membrane dimension A in FIG. 2) is smaller than the diameter of the flat portion of the film-like member (twice the liquid chamber member dimension B in FIG. 2). This prevents air from remaining in the protruding portion of the liquid chamber member, enabling stable ejection.

[0107] In this embodiment, the vibrator vibrates the film member in response to a voltage applied through wiring connected to the electrodes via a conductive adhesive. This configuration facilitates electrical connection between the vibrator and the wiring.

[0108] In this embodiment, the wiring is housed inside a housing portion (groove portion) formed on the outer surface of the liquid chamber member. This configuration prevents the wiring from protruding from the outer surface of the liquid chamber member, and prevents the ejection head from hitting the inner wall of the well when the nozzle hole 621 is placed inside the well. As a result, droplets containing tissues can be placed with high precision.

[0109] In addition, a modification of this embodiment includes a first piezoelectric element that vibrates the film member and a second piezoelectric element that detects the back electromotive force. This configuration allows the first piezoelectric element and the second piezoelectric element to be provided in a simpler configuration.

[0110] Furthermore, the droplet discharge method according to this embodiment can also be said to be a method for manufacturing a container containing textured bodies, since textured bodies contained in droplets are disposed in the container.

[0111] [Second embodiment] In this embodiment, at least one of the current and voltage generated by the vibration unit that vibrates the film-like member that ejects droplets from the nozzle holes is detected, and factors that contribute to the vibration characteristics of the film-like member are controlled based on the detection results. For example, the back electromotive force generated by the piezoelectric element serving as the vibration unit is detected, and the amount of liquid that contributes to the resonance period of the film-like member is controlled based on this back electromotive force. This allows for accurate control of the vibration of the film-like member.

[0112] <Example of Overall Configuration of Droplet Discharge Device 100a> First, the overall configuration of the droplet ejection device 100a will be described with reference to Fig. 12. Fig. 12 is a diagram illustrating an example of the overall configuration of the droplet ejection device 100a.

[0113] As shown in FIG. 12, the droplet discharge device 100a includes a supply unit 2, an ammeter 3, and a control unit 4a.

[0114] One end of the ejection head 1 is inserted into wells 51, which are a number of well-shaped holes formed in a well plate 5, which is a flat member.

[0115] The supply unit 2 is configured to include a liquid delivery pump and a suction pump, and delivers liquid to a chamber that holds the liquid within the discharge head 1 via a tube 21 and a supply needle 22, and also sucks (absorbs) the liquid from the chamber. The amount of liquid (liquid volume) in the chamber can be changed by the liquid delivery or absorption by the supply unit 2.

[0116] The ejection head 1 ejects the liquid in the chamber and supplies the liquid into the well 51. The supplied liquid allows formation of tissue or the like in the well 51.

[0117] A MEMS chip 6 is provided at the end of the ejection head 1 that is inserted into the well 51. A drive waveform generator 7 applies a drive waveform (drive voltage) to the MEMS chip 6 via wiring 71 and 72, causing the liquid held in the MEMS chip 6 to be ejected into the well 51 as droplets D.

[0118] The ammeter 3, which is an example of a detection unit, is a detector that detects a current generated in a piezoelectric element included in the MEMS chip 6 in response to the ejection of liquid by the MEMS chip 6.

[0119] The control unit 4a is a control device that controls the overall operation of the droplet discharge device 100. The control unit 4a also has a function of causing the supply unit 2 to send or absorb liquid in accordance with the back electromotive force of the piezoelectric element based on the current detected by the ammeter 3, and controlling the amount of liquid held in the chamber of the MEMS chip 6 (see liquid amount E in FIG. 2).

[0120] When residual vibration occurs in the membrane 62 due to driving, the residual vibration deforms the piezoelectric body 631, generating a back electromotive force between the lower electrode 632 and the upper electrode 633. Here, the residual vibration of the membrane 62 refers to the vibration remaining in the membrane 62 when the driving state is changed to the stopped state.

[0121] The piezoelectric element used to detect back electromotive force may be the piezoelectric element driven for ejection, or a separate piezoelectric element may be provided for detection, as described in FIG. 6. The piezoelectric element 63a and piezoelectric element 63 shown in FIG. 6 have either the upper electrode or the lower electrode configured electrically independent, and can be used separately as a driving piezoelectric element and a piezoelectric element for current / voltage detection. Either piezoelectric element 63a or piezoelectric element 63b may be used for driving and either may be used for detection. This configuration eliminates the need to switch between the driving circuit and the signal detection circuit, allowing for a simpler device to be configured.

[0122] <Example of current flowing through piezoelectric element 63> Here, the current generated in the piezoelectric element 63 will be described with reference to Fig. 13. Fig. 13 is a diagram illustrating an example of the current generated in the piezoelectric element 63. In Fig. 13, drive waveform 131 is a graph showing an example of the drive waveform, vibration displacement 132 is a graph showing an example of the vibration displacement of membrane 62, and current waveform 133 is a graph showing an example of the current waveform detected by ammeter 3.

[0123] 13, as shown in drive waveform 131, when the voltage of the drive waveform rises from time t1 and driving of piezoelectric element 63 begins, the vibration displacement of membrane 62 rises, as shown in vibration displacement 132. Thereafter, at time t2 when the voltage rise of the drive waveform stops, the vibration displacement of membrane 62 reaches a maximum. As shown in current waveform 133, current continues to flow during the period when the voltage is rising from time t1 to time t2, and stops flowing when time t2 is reached.

[0124] After that, the driving of the piezoelectric element 63 is stopped, but the membrane 62 is displaced by the residual vibration. At time t3, the current value reaches an extreme value when the speed of the vibration displacement reaches a maximum. After that, at time t4, when the speed of the vibration displacement of the membrane 62 reaches zero, the current value returns to zero.

[0125] In this way, a current is generated in synchronization with the vibration displacement of the residual vibration of the membrane 62. In this embodiment, this current is detected by the ammeter 3, and a voltage value corresponding to the current value is detected as the back electromotive force. The resonance period T0 of the membrane 62 is also detected from the time interval between extreme values ​​in the time change of the back electromotive force. However, the time interval between extreme values ​​of the current can also be detected as the resonance period T0.

[0126] Furthermore, the resonance period T0 changes depending on the liquid volume E of the liquid 200 held in the chamber 61. Therefore, in this embodiment, the control unit 4 controls the liquid volume E of the liquid 200 held in the chamber 61 depending on the detection result of the resonance period T0 of the membrane 62, and changes the resonance period T0 to match a predetermined time difference (described later) in the drive waveform. This resonance period T0 is an example of a vibration characteristic and an example of a vibration period.

[0127] <Example of functional configuration of control unit 4a> Here, the functional configuration of the control unit 4a in the droplet discharge device 100 will be described with reference to Fig. 14. Fig. 14 is a block diagram illustrating an example of the functional configuration of the control unit 4a.

[0128] As shown in Fig. 14, the control unit 4a includes a discharge control unit 41, a supply control unit 42, a factor control unit 43, and a storage unit 44. Of these, the functions of the discharge control unit 41, the supply control unit 42, and the factor control unit 43 are realized by electric circuits, and some of these functions can also be realized by software (CPU; Central Processing Unit). These functions may also be realized by multiple circuits or multiple pieces of software. The function of the storage unit 44 is realized by a storage device such as an HDD (Hard Disk Drive).

[0129] The discharge control unit 41 controls the application of a drive waveform to the MEMS chip 6 by the drive waveform generation source 7, thereby controlling the discharge of droplets by the MEMS chip 6. In addition, the supply control unit 42 controls the supply of liquid to the MEMS chip 6 by the supply unit 2.

[0130] The factor control unit 43 controls the amount of liquid E held in the chamber 61 by causing the supply unit 2 to send or absorb liquid in accordance with the back electromotive force of the piezoelectric element 63 detected based on the current detected by the ammeter 3.

[0131] The relationship between the deviation ΔT0 from the set value of the resonance period T0 of the membrane 62 and the liquid volume E is determined in advance and stored in the storage unit 44. The factor control unit 43 detects the deviation ΔT0 from the back electromotive force of the piezoelectric element 63, and acquires liquid volume information that serves as the control target value by referring to the storage unit 44. Then, the supply unit 2 is caused to send or absorb liquid, and the liquid volume E held in the chamber 61 can be controlled to become the control target value.

[0132] <Operation Example of Droplet Discharge Device 100a> Next, the operation of the droplet ejection device 100a will be described with reference to Fig. 15. Fig. 15 is a flowchart illustrating an example of the operation of the droplet ejection device 100a.

[0133] First, in step S101, the supply control unit 42 drives the supply unit 2 to initially fill the chamber 61 with the liquid 200.

[0134] Next, in step S102, the discharge control unit 41 drives the drive waveform generation source 7 to apply a predetermined test drive waveform to the piezoelectric element 63, causing it to be discharged from the MEMS chip 6. The ammeter 3 detects the back electromotive force of the piezoelectric element 63 at that time, and the factor control unit 43 detects the resonance period T0 of the membrane 62 based on the detection value of the ammeter 3.

[0135] Thereafter, the factor control unit 43 determines whether the resonance period T0 of the membrane 62 is equal to or less than a predetermined setting range. This setting range is a range that is predetermined on both the minus and plus sides of the set value of the resonance period T0. "Below the setting range" means that the resonance period T0 is equal to or less than the setting range on the minus side of the set value of the resonance period T0, in other words, that the resonance period T0 is too small. "Above the setting range" means that the resonance period T0 is equal to or greater than the setting range on the plus side of the set value of the resonance period T0, in other words, that the resonance period T0 is too large.

[0136] If it is determined in step S102 that the resonance period T0 is equal to or less than the set range (step S102, Yes), in step S103, the factor control unit 43 refers to the storage unit 44 and acquires liquid volume information that is the control target value based on the deviation ΔT0 of the resonance period T0 from the set value. Then, the supply unit 2 is caused to send liquid, and liquid is added so that the liquid volume E held in the chamber 61 becomes the control target value. This increases the liquid volume E, and the resonance period T0 changes to the desired value. Thereafter, the operation returns to step S102, and the operation of step S102 is performed again.

[0137] On the other hand, if it is determined in step S102 that the resonance period T0 of the membrane 62 is not equal to or greater than the set range (step S102, No), then in step S104, the factor control unit 43 determines whether the resonance period T0 of the membrane 62 is equal to or greater than a predetermined set range.

[0138] If it is determined in step S104 that the resonance period T0 is equal to or greater than the set range (step S104, Yes), in step S105, the factor control unit 43 refers to the storage unit 44 and acquires liquid volume information that is the control target value based on the deviation ΔT0 of the resonance period T0 from the set value. Then, the supply unit 2 is caused to suck up the liquid so that the liquid volume E held in the chamber 61 becomes the control target value. This reduces the liquid volume E, and the resonance period T0 changes to the desired value. Thereafter, the operation returns to step S104, and the operation of step S104 is performed again.

[0139] On the other hand, if it is determined in step S104 that the value is not greater than the set range (step S104, No), in step S106, the ejection control unit 41 drives the drive waveform generating source 7 to apply a predetermined ejection drive waveform to the piezoelectric element 63, causing the MEMS chip 6 to eject a droplet D.

[0140] Subsequently, in step S107, the control unit 4 determines whether or not to terminate the discharge by the droplet discharge device 100. This determination is made based on the operation of the droplet discharge device 100 by the user, etc.

[0141] If it is determined in step S107 that the operation is to be completed (step S107, Yes), the droplet ejection device 100 completes the operation, and if it is determined that the operation is not to be completed (step S107, No), the process returns to step S102, and the operations from step S102 onwards are performed again.

[0142] In this way, the droplet ejection device 100a can eject droplets D while controlling the liquid volume E. Here, in the example shown in Fig. 15, an operation of sucking up the liquid 200 is included, but if it is only required to add the liquid 200 that has decreased due to ejection, the determination of whether the resonance period T0 is equal to or greater than the set range (step S104) may be omitted.

[0143] <Functions and Effects of the Droplet Discharge Device 100a> Next, the effects of the droplet ejection device 100a will be described.

[0144] In the droplet ejection device according to the first embodiment, when a large amount of liquid is ejected continuously, the resonance period of the membrane fluctuates due to fluctuations in the amount of liquid, and stable ejection may not be possible due to a mismatch between the resonance period T0 of the membrane 62 and the drive waveform. This mismatch between the resonance period T0 and the drive waveform is, for example, a mismatch between the resonance period T0 and the "time difference in the drive waveform" described above.

[0145] One possible method for detecting the membrane's resonance period with high sensitivity is to use a measuring instrument such as a laser Doppler vibrometer, but this requires an optical system to be placed opposite the membrane in order to irradiate the membrane with laser light as a probe light, making it virtually impossible to measure the membrane by irradiating it with laser light while it is placed in a well.

[0146] Another possible method is to estimate the resonance period of the membrane by measuring the liquid level, but this configuration does not actually measure the resonance period of the membrane, but rather estimates the resonance period, making it difficult to measure the resonance period of the membrane with high accuracy. Furthermore, if air bubbles are present on the chamber wall or other surfaces in the liquid within chamber 61, the resonance period of the membrane will fluctuate due to the effect of compression caused by the air bubbles, and so the resonance period of the membrane cannot be measured with sufficient accuracy by measuring the liquid level alone.

[0147] In contrast, in this embodiment, the back electromotive force generated by the piezoelectric element 63 that vibrates the membrane 62 that ejects droplets D from the nozzle hole 621 is detected, and the liquid volume E in the chamber 61, which contributes to the vibration characteristics of the membrane 62, is controlled based on the detection result. This allows the resonance period T0, which changes depending on the liquid volume E, to be controlled to a desired value, thereby accurately controlling the vibration of the membrane 62. Then, by matching the resonance period T0 of the membrane 62 to the "time difference in the drive waveform," ejection defects can be suppressed and droplets D can be ejected stably.

[0148] Also, although it is possible to detect the back electromotive force itself with a bulk or sheet piezoelectric element, the detection sensitivity may be low. Although it is possible to design to increase the vibration displacement in order to increase the detection sensitivity, in this case, it is required to use a membrane with a vibration displacement larger than the range in which the ejection head can be preferably ejected. Therefore, it may be difficult to achieve both stabilization of ejection and ensuring of detection sensitivity.

[0149] On the other hand, in this embodiment, since the membrane 62 is formed on the MEMS chip 6, the membrane 62 can be miniaturized, and thereby the vibration displacement for preferably ejecting can be increased. For example, in a general membrane, the vibration displacement for preferably ejecting is about 0.1 μm, whereas in the membrane 62 according to this embodiment, ejection can be preferably performed with a vibration displacement of several μm to several tens of μm. As a result, while performing stable ejection, a large back electromotive force can be obtained with a large vibration displacement, and high-sensitivity detection of the back electromotive force becomes possible. As a result, it is possible to achieve both stabilization of ejection and ensuring of detection sensitivity.

[0150] Note that other effects are the same as those described in the first embodiment.

[0151] [Third Embodiment] Next, a droplet ejection device according to the third embodiment will be described.

[0152] In this embodiment, an adjustment member is provided at a position facing the nozzle hole formed in the membrane member so as to be in contact with at least a part of the liquid in the liquid chamber. By controlling the distance between the nozzle hole and the adjustment member as a factor contributing to the vibration characteristics of the membrane member based on at least the current or voltage generated by the vibration unit, the vibration of the membrane member is accurately controlled.

[0153] <Configuration Example of MEMS Chip 6a> Here, FIG. 16 is a diagram for explaining an example of the configuration of the MEMS chip 6a of the droplet ejection device 100b according to this embodiment.

[0154] 16, the MEMS chip 6a has an adjustment member 64 at a position facing the nozzle hole 621 formed in the membrane 62. The adjustment member 64 is provided so that at least a surface 64a of the adjustment member 64 facing the membrane 62 (a surface on the −Z direction side) is disposed at a position where it comes into contact with the liquid 200 filled in the chamber 61.

[0155] When the position (height) of the adjustment member 64 in the Z direction is adjusted within the range in which the opposing surface 64a is in contact with the liquid 200, the distance F between the nozzle hole 621 and the opposing surface 64a of the adjustment member 64 changes. This changes the volume of the portion of the adjustment member 64 that has entered the liquid 200, and the height of the liquid surface 200a of the liquid 200 changes in response to this volume change, thereby changing the resonance period T0 of the membrane 62. Therefore, by adjusting the height of the adjustment member 64 to control the distance F, it becomes possible to change the resonance period T0 of the membrane 62 without changing the liquid volume E.

[0156] The size of the adjustment member 64 can be determined appropriately according to the required sensitivity, since the sensitivity of changing the height of the liquid surface 200a according to the distance F varies depending on the size of the adjustment member 64. There are no particular restrictions on the material of the adjustment member 64, and for example, metal materials, ceramic materials, polymer materials, etc. can be used.

[0157] Furthermore, the position of the adjustment member 64 in the Z direction can be adjusted by the control unit 4a driving the actuator 8 connected to the adjustment member 64. As the actuator 8, one driven by a piezoelectric element, one driven by a motor, or the like can be used.

[0158] <Example of functional configuration of control unit 4b> Fig. 17 is a block diagram showing an example of the functional configuration of the control unit 4b. As shown in Fig. 17, the control unit 4b includes a factor control unit 43a and a storage unit 44a. The factor control unit 43a drives the actuator 8 to control the distance F between the nozzle hole 621 and the adjustment member 64.

[0159] The relationship between the deviation ΔT0 from the set value of the resonance period T0 of the membrane 62 and the distance F is determined in advance and stored in the storage unit 44a. The factor control unit 43a detects the deviation ΔT0 from the back electromotive force of the piezoelectric element 63 and acquires distance information that serves as the control target value by referring to the storage unit 44a. Then, the actuator 8 is driven to control the distance F between the nozzle hole 621 and the adjustment member 64 to the control target value.

[0160] <Operation Example of Droplet Discharge Device 100b> Next, the operation of the droplet ejection device 100b will be described with reference to Fig. 18. Fig. 18 is a flowchart illustrating an example of the operation of the droplet ejection device 100b. Note that the operations of steps S141 and S142 in Fig. 18 are similar to the operations of steps S101 and S102 in Fig. 15, and the operations of steps S146 and S147 in Fig. 18 are similar to the operations of steps S106 and S107 in Fig. 15. Therefore, redundant explanations of these will be omitted here.

[0161] If it is determined in step S142 that the resonance period T0 is equal to or less than the set range (Yes in step S142), in step S143, the factor control unit 43a refers to the storage unit 44a and acquires distance information that is the control target value based on the deviation ΔT0 of the resonance period T0 from the set value. Then, the actuator 8 is driven to lower the adjustment member 64 so that the distance F becomes the control target value. This causes the liquid surface 200a of the liquid 200 to rise, and the resonance period T0 changes to the desired value. Thereafter, the operation returns to step S142, and the operation of step S142 is performed again.

[0162] On the other hand, if it is determined in step S142 that the resonance period T0 of the membrane 62 is not equal to or greater than the set range (step S142, No), then in step S144, the factor control unit 43a determines whether the resonance period T0 of the membrane 62 is equal to or greater than a predetermined set range.

[0163] If it is determined in step S144 that the resonance period T0 is equal to or greater than the set range (step S144, Yes), in step S145, the factor control unit 43a refers to the storage unit 44a and acquires distance information that is the control target value based on the deviation ΔT0 of the resonance period T0 from the set value. Then, the actuator 8 is driven to raise the adjustment member 64. This causes the liquid surface 200a of the liquid 200 to descend, and the resonance period T0 changes to the desired value. Thereafter, the operation returns to step S144, and the operation of step S144 is performed again.

[0164] In this way, the droplet ejection device 100b can eject droplets D while controlling the distance F.

[0165] As described above, in this embodiment, the adjustment member 64 is provided at a position facing the nozzle hole 621 formed in the membrane 62 so that at least a portion of it comes into contact with the liquid 200 in the chamber 61. By controlling the distance F between the nozzle hole 621 and the adjustment member 64 as a factor that contributes to the vibration characteristics of the membrane 62 based on at least the current or voltage generated by the piezoelectric element 63, it is possible to accurately control the vibration of the membrane 62 with a simpler configuration without changing the liquid volume E.

[0166] Other effects are the same as those described in the first and second embodiments.

[0167] The best mode for carrying out the present invention has been described above using examples, but the present invention is not limited to these examples, and various modifications and substitutions can be made within the scope that does not deviate from the gist of the present invention.

[0168] For example, a droplet ejection device includes a liquid chamber for holding a liquid, an atmosphere opening section for opening the liquid chamber to the atmosphere, a film-like member in which a nozzle hole is formed and which ejects the liquid held in the liquid chamber as droplets from the nozzle hole by vibration, a vibration section for vibrating the film-like member, a detection section for detecting at least one of the current or voltage generated by the vibration section, and a control section for controlling factors that contribute to the vibration characteristics of the film-like member based on at least one of the current or voltage.

[0169] For example, the voltage is a back electromotive force.

[0170] The vibration unit includes a piezoelectric element.

[0171] The film member and the vibration applying section are integrally formed by a semiconductor process, the vibration characteristic is a vibration period, and the vibration period is a resonance period.

[0172] The control unit also detects the vibration period from the time interval between extreme values ​​in the time change of at least one of the current or the voltage, and controls the factor so that the vibration period coincides with a predetermined time difference in the drive waveform for vibrating the vibration unit.

[0173] The droplet ejection device also includes a supply unit that changes the amount of liquid in the liquid chamber by sending or absorbing the liquid, and the control unit drives the supply unit to control the amount of liquid in the liquid chamber.

[0174] The droplet ejection device further includes an adjustment member disposed opposite the nozzle hole so as to be in contact with at least a portion of the liquid, and the control unit controls the distance between the nozzle hole and the adjustment member by changing the position of the adjustment member. The liquid is a cell suspension in which cells are suspended.

[0175] The droplet ejection device also has a supply unit that changes the amount of liquid in a liquid chamber that holds the liquid by sending or absorbing the liquid, and the control unit drives the supply unit to control the amount of liquid in the liquid chamber.

[0176] The droplet ejection device also includes an adjustment member that faces the nozzle hole and is arranged so that at least a portion of the adjustment member is in contact with the liquid, and the control unit controls the distance between the nozzle hole and the adjustment member by changing the position of the adjustment member.

[0177] The droplet ejection device described above controls the resonance period, which changes depending on the amount of liquid, to a desired value, thereby accurately controlling the vibration of the film-like member. By matching the resonance period of the film-like member to the "time difference in the drive waveform," ejection defects can be suppressed and droplets can be ejected stably. [Explanation of symbols]

[0178] 1 Discharge head 2 Supply section 21 tubes 22 Supply needle 3 Ammeter (example of detection unit) 4. Control Unit 41 Discharge control section 42 Supply control section 43 Factor Control Section 44 Storage area 5 well plate (an example of a container) 51 well (an example of a recess) 6 MEMS chip (example of vibration part) 61 Chamber (an example of a liquid chamber) 611 Atmospheric vent 612 Liquid chamber member 612a Groove for bottom electrode (an example of a groove) 612b Groove for upper electrode (an example of a groove) 613 Elastic Members 62 Membrane (an example of a membrane-like material) 621 Nozzle hole 63 Piezoelectric element (an example of a vibrating part) 63a Piezoelectric element (an example of a first piezoelectric element) 63b Piezoelectric element (an example of the second piezoelectric element) 631 Piezoelectric 632 Lower electrode 633 Upper electrode 64 Adjustment parts 64a Opposite surface 65 Membrane support part (an example of a support member) 7. Drive waveform source 8 Actuators 9. Head actuator (example of arrangement) 71,72 Wiring 711 Conductive adhesive 712 Wiring connection 712a Lower wiring connection 712b Upper wiring connection 713a Lower electrode connection part 713b Upper electrode connection part 714a Bottom electrode wiring 714b Upper electrode wiring 715 Interlayer insulating film 716 Insulating film 100 Droplet discharge device 200 Liquid (Example of cell suspension) 250 Sedimenting particles (an example of a cell) D droplet P1,P2,P3 waveform elements T0 resonance period (example of vibration characteristics, example of vibration period) T 12 , T 23 Time difference (example of a specified time difference) E. Liquid volume (an example of a factor) F distance (an example of a factor) A Membrane dimensions B Liquid chamber component dimensions [Prior art documents] [Patent documents]

[0179] [Patent Document 1] Patent No. 6543927

Claims

1. A droplet ejection method using a droplet ejection device that ejects droplets from nozzle holes formed in a film-like member, a positioning step of positioning the nozzle hole inside a recessed portion provided in a container; a discharge step of discharging the droplets from the nozzle hole disposed inside the recess, In the arranging step, a vibrating unit including the film member, a support member that supports the film member, and a vibrating unit that vibrates the film member is arranged inside the recess. Droplet ejection method.

2. A droplet ejection method using a droplet ejection device that ejects droplets from nozzle holes formed in a film-like member, a positioning step of positioning the nozzle hole inside a recessed portion provided in a container; a discharge step of discharging the droplets from the nozzle hole disposed inside the recess, In the arranging step, the nozzle holes are arranged at a depth of 70% or more of the depth of the recessed portion. Droplet ejection method.

3. A droplet ejection method using a droplet ejection device that ejects droplets from nozzle holes formed in a film-like member, a positioning step of positioning the nozzle hole inside a recessed portion provided in a container; a discharge step of discharging the droplets from the nozzle hole disposed inside the recess, The outer shape of the flat surface of the recess and the outer shape of the flat surface of the film member are both circular, and the diameter of the film member is smaller than the diameter of the flat surface of the recess. Droplet ejection method.

4. The droplets contain a biological or biocompatible material. The droplet ejection method according to claim 1 .

5. In the arranging step, the nozzle holes are arranged at a depth of 70% or more of the depth of the recessed portion. The droplet ejection method according to claim 1 .

6. The outer shape of the flat surface of the recess and the outer shape of the flat surface of the film member are both circular, and the diameter of the film member is smaller than the diameter of the flat surface of the recess. The droplet ejection method according to claim 1 or 2.

7. A method for manufacturing a tissue-containing container using a droplet ejection device that ejects droplets from nozzle holes formed in a film-like member, comprising: a positioning step of positioning the nozzle hole inside a recessed portion provided in a container; a discharge step of discharging the droplet containing the tissue from the nozzle hole disposed inside the recess, In the arranging step, a vibration unit including the film-like member, a support member that supports the film-like member, and a vibration unit that vibrates the film-like member is arranged inside the recess. A method for manufacturing a container containing tissue.

8. A droplet ejection device including a droplet ejection head, The ejection head includes a film-like member including nozzle holes, and a support member that supports the film-like member. a vibration unit including a vibration unit disposed on a part of the film member and a part of the support member, the vibration unit vibrating the film member; a liquid chamber member joined to the vibration section to hold liquid; a placement section for placing the vibration section inside a recessed section provided in the container, The vibrating section is joined to an end of the liquid chamber member along the direction in which the droplets are ejected.

9. The vibration part is integrally molded by a semiconductor process. The droplet ejection device according to claim 8 .

10. The vibration portion is joined to the liquid chamber member via an elastic member. The droplet ejection device according to claim 8 .

11. The outer shape of the flat surface of the film-like member is circular, the liquid chamber member is a cylindrical member, and the inner diameter of the end of the liquid chamber member on the side where the elastic member is disposed is smaller than the diameter of the flat surface of the film-like member. The droplet ejection device according to claim 10.

12. The vibrating unit vibrates the film member in response to a voltage applied through wiring connected to a plurality of electrodes via a conductive adhesive. The droplet ejection device according to any one of claims 8 to 11.

13. The wiring is accommodated inside a housing portion formed on the outer surface of the liquid chamber member. The droplet ejection device according to claim 12.

14. The liquid is a cell suspension containing cells. The droplet ejection device according to any one of claims 8 to 13.

15. The vibrating unit includes a piezoelectric element. The droplet ejection device according to any one of claims 8 to 14.

16. a detection unit that detects at least one of a current and a voltage generated by the excitation unit; a control unit that controls factors that contribute to the vibration characteristics of the film member based on at least one of the current and the voltage. The droplet ejection device according to any one of claims 8 to 15.

17. The voltage is the back electromotive force generated by the deformation of the piezoelectric element. The droplet ejection device according to claim 16.

18. The piezoelectric element includes a first piezoelectric element that vibrates the film member and a second piezoelectric element that detects the back electromotive force. The droplet ejection device according to claim 17.

19. The vibration characteristic is a vibration period. The droplet ejection device according to any one of claims 16 to 18.

Images