JP6844659B2 - Droplet forming device - Google Patents

Description

The present invention relates to a droplet forming apparatus.

In recent years, with the progress of stem cell technology, the development of a technique for forming a tissue by ejecting a plurality of cells by an inkjet has been carried out. Examples of the inkjet method include a piezoelectric pressurization method using a piezoelectric element, a thermal method using a heater, and an electrostatic method in which a liquid is pulled by an electrostatic attraction. Among these, the piezoelectric pressurization method is more suitable for use for forming droplets of a cell solution because it is less likely to damage cells by heat or electric field than other methods.

In the conventional general piezoelectric pressurization type inkjet head, droplets are formed by utilizing the compression of the liquid in the pressurizing liquid chamber. Therefore, when air bubbles are mixed in the pressurized liquid chamber, the liquid cannot be compressed, and there is a problem that the liquid is not discharged. The solvent of the cell solution is water, and the surfactant used in general inkjet ink cannot be used because it damages the cells, and because of its high surface tension, it is easy to entrain bubbles, which is a big problem. was there.

Further, in a general inkjet head, in order to return from a state in which air bubbles are mixed to a normal state, a large amount of liquid is discharged from the nozzle part by pressurizing the liquid chamber or sucking the liquid from the nozzle part. The air bubbles are removed at the same time. However, it is not desirable to eliminate air bubbles by this technique because cell solutions are more expensive and valuable than ordinary inkjet inks.

On the other hand, there is disclosed a small water droplet manufacturing apparatus that sprays a liquid on a membrane by vibrating the membrane with a bending mode actuator. With this device, it is possible to directly fly the liquid formed on the membrane without using the pressing force in the liquid chamber. Therefore, the influence of air bubbles can be reduced as compared with a general inkjet head (see, for example, Patent Document 1).

However, when the above device is used to form droplets of a cell solution, the natural frequency of the membrane shifts due to the presence of air bubbles remaining in the liquid chamber. The formation state is affected. Therefore, it is difficult to stably discharge the cell solution over a long period of time.

The present invention has been made in view of the above points, and an object of the present invention is to provide a droplet forming apparatus capable of stably ejecting a cell solution.

In this droplet forming apparatus, a liquid holding portion that holds a cell solution containing cells so that the upper part thereof communicates with the atmosphere and a nozzle are formed, and the cell solution held in the liquid holding portion is vibrated. It is required to have a film-like member for discharging as droplets from the nozzle, and an upper lid having a hole formed above the liquid holding portion having a cross-sectional area smaller than that of the liquid holding portion.

According to the disclosed technique, it is possible to provide a droplet forming apparatus capable of stably ejecting a cell solution.

It is sectional drawing which illustrates the droplet forming apparatus which concerns on 1st Embodiment. It is a figure which illustrates the voltage applied to the upper and lower electrodes of a piezoelectric element. It is a figure which illustrates the process of forming a droplet. It is sectional drawing (the 1) which illustrates the droplet forming apparatus which concerns on the modification 1 of the 1st Embodiment. FIG. 2 is a cross-sectional view (No. 2) illustrating the droplet forming apparatus according to the first modification of the first embodiment. FIG. 3 is a cross-sectional view (No. 3) illustrating the droplet forming apparatus according to the first modification of the first embodiment. It is sectional drawing which illustrates the droplet forming apparatus which concerns on modification 2 of 1st Embodiment. It is sectional drawing (the 1) which illustrates the droplet forming apparatus which concerns on the modification 3 of the 1st Embodiment. FIG. 2 is a cross-sectional view (No. 2) illustrating the droplet forming apparatus according to the third modification of the first embodiment. FIG. 3 is a cross-sectional view (No. 3) illustrating the droplet forming apparatus according to the third modification of the first embodiment. It is sectional drawing (the 4) which illustrates the droplet forming apparatus which concerns on the modification 3 of the 1st Embodiment.

Hereinafter, modes for carrying out the invention will be described with reference to the drawings. In each drawing, the same components may be designated by the same reference numerals and duplicate description may be omitted.

<First Embodiment>
[Structure of droplet forming device]
First, the droplet forming apparatus according to the first embodiment will be described. FIG. 1 is a cross-sectional view illustrating the droplet forming apparatus according to the first embodiment. With reference to FIG. 1, the droplet forming apparatus 10 includes a liquid chamber 11, a membrane 12, and a piezoelectric element 13. FIG. 1 schematically shows a state in which a cell solution 300 containing cells 350 is held in the liquid chamber 11.

In the present embodiment, for convenience, the liquid chamber 11 side is on the upper side and the piezoelectric element 13 side is on the lower side. Further, the surface of each part on the liquid chamber 11 side is the upper surface, and the surface on the piezoelectric element 13 side is the lower surface. Further, the plan view means that the object is viewed from the normal direction of the upper surface of the membrane 12, and the planar shape refers to the shape of the object viewed from the normal direction of the upper surface of the membrane 12.

In the droplet forming apparatus 10, the liquid chamber 11 is a liquid holding portion that holds the cell solution 300 containing the cells 350 (where the cells 350 are dispersed), and may be formed of, for example, metal, silicon, ceramic, or the like. it can. The liquid chamber 11 has an atmospheric opening portion 111 that opens the inside of the liquid chamber 11 to the atmosphere at the upper part, and is configured so that bubbles mixed in the cell solution 300 can be discharged from the atmospheric opening portion 111.

The membrane 12 is a film-like member fixed to the lower end of the liquid chamber 11. A nozzle 121, which is a through hole, is formed at substantially the center of the membrane 12, and the cell solution 300 held in the liquid chamber 11 is discharged as a droplet from the nozzle 121 by the vibration of the membrane 12. The planar shape of the membrane 12 can be, for example, circular, but may be elliptical, quadrangular, or the like.

The material of the membrane 12 is not particularly limited, but if it is too soft, the membrane 12 easily vibrates, and it is difficult to immediately suppress the vibration when it is not discharged. Therefore, it is preferable to use a material having a certain degree of hardness. .. As the material of the membrane 12, for example, a metal material, a ceramic material, a polymer material having a certain degree of hardness, or the like can be used. In particular, it is preferable that the material has low adhesion to the cells 350.

It is generally said that the cell adhesion depends on the contact angle of the material with water, and when the material has high hydrophilicity or hydrophobicity, the cell adhesion is low. Various metal materials and ceramics (metal oxides) can be used as the material having high hydrophilicity, and fluororesin or the like can be used as the material having high hydrophobicity.

Examples of such materials include stainless steel, nickel, aluminum and the like, silicon dioxide, alumina, zirconia and the like. In addition, coating the surface of the material may reduce cell adhesion. The surface of the material may be coated with the above-mentioned metal or metal oxide material, or a synthetic phospholipid polymer imitating a cell membrane (for example, NOF). It is also possible to coat with Lipidure) manufactured by Oil Co., Ltd.

It is preferable that the nozzle 121 is formed as a substantially circular through hole at the substantially center of the membrane 12. In this case, the diameter of the nozzle 121 is not particularly limited, but it is preferably twice or more the size of the cell 350 in order to prevent the cells 350 from clogging the nozzle 121. Specifically, since the size of animal cells, particularly human cells, is generally about 10 μm to 30 μm, it is preferable that the diameter of the nozzle 121 is 20 μm to 60 μm or more according to the cells to be used.

On the other hand, if the droplets become too large, it becomes difficult to achieve the purpose of forming fine droplets, so the diameter of the nozzle 121 is preferably 200 μm or less. That is, in the droplet forming apparatus 10 according to the present embodiment, the diameter of the nozzle 121 is typically in the range of 20 μm to 200 μm.

The piezoelectric element 13 is formed on the lower surface side of the membrane 12. The shape of the piezoelectric element 13 can be designed according to the shape of the membrane 12. For example, when the planar shape of the membrane 12 is circular, it is preferable to form the piezoelectric element 13 having an annular (ring-shaped) planar shape around the nozzle 121.

The piezoelectric element 13 has, for example, a structure in which electrodes for applying a voltage are provided on the upper surface and the lower surface of the piezoelectric material. By applying a voltage to the upper and lower electrodes of the piezoelectric element 13, compressive stress is applied in the lateral direction of the paper surface to apply a membrane. 12 can be vibrated. As the piezoelectric material, for example, lead zirconate titanate can be used. In addition to this, various piezoelectric materials such as bismuth iron oxide, metal niobate, barium titanate, or these materials to which a metal or a different oxide is added can be used.

However, the vibrating means for vibrating the membrane 12 is not limited to the piezoelectric element 13. For example, by attaching a material having a linear expansion coefficient different from that of the membrane 12 on the membrane 12 and heating the membrane 12, it is possible to vibrate the membrane 12 by utilizing the difference in the linear expansion coefficient. At this time, it is preferable that the heater is formed of a material having a different coefficient of linear expansion, and the heater is heated by energization to vibrate the membrane 12.

Cell 350 is, for example, an animal cell, particularly a cell of human origin. The cell solution 300 contains a cell dispersion in addition to the cells 350, and water having a high affinity with the cells 350 can be used as the main component of the cell dispersion. Further, it is preferable that the aqueous solution contains a salt for adjusting the osmotic pressure with the cells 350 and a pH adjusting agent for adjusting the pH. More specifically, as the cell dispersion, a pH-adjusted Tris buffer aqueous solution or a PBS solution in which metal salts such as Ca, K, and Na are added in the same manner as the culture solution can be used.

Alternatively, the cell dispersion can be used without particular limitation as long as it is a cell culture medium usually used in the art. For example, depending on the type of cell 350 used, MEM medium, BME medium, DME medium, αMEM medium, IMDM medium, ES medium, DM-160 medium, Fisher medium, F12 medium, WE medium, RPMI1640 medium, etc., published by Asakura Shoten. The basal medium described on page 581 of "Tissue Culture Technology, Third Edition, edited by the Japan Society for Tissue Culture" can be used.

Further, serum (fetal bovine serum, etc.), various growth factors, antibiotics, amino acids, etc. may be added to the basal medium. Further, a commercially available serum-free medium such as Gibco serum-free medium (Invitrogen) can be used. Considering the clinical application of the finally obtained cell tissue, it is preferable to use a medium containing no animal-derived components.

[Drop formation process of droplet forming device]
Next, the process of forming droplets by the droplet forming apparatus according to the first embodiment will be described. FIG. 2 is a diagram illustrating the voltage applied to the upper and lower electrodes of the piezoelectric element. FIG. 3 is a diagram illustrating the process of forming droplets.

When the pulsed voltage shown in FIG. 2 is applied to the upper and lower electrodes of the piezoelectric element 13 of the droplet forming apparatus 10, droplets are formed as shown in FIG. First, at the timing of A in FIG. 2, as shown in FIG. 3A, the membrane 12 is rapidly deformed, so that a high pressure is applied between the cell solution 300 held in the liquid chamber 11 and the membrane 12. It is generated, and this pressure pushes the droplet 310 out of the nozzle 121.

Next, at the timing of B in FIG. 2, as shown in FIG. 3 (b), the liquid is continuously extruded from the nozzle 121 for a time until the pressure is relaxed upward, and the droplet 310 grows. Finally, at the timing of C in FIG. 2, as shown in FIG. 3 (c), when the membrane 12 returns to the original state, the liquid pressure near the interface between the cell solution 300 and the membrane 12 decreases, and the cells A droplet 310 containing 350 is formed.

In the droplet forming apparatus 10, air bubbles may be mixed in the cell solution 300 in the liquid chamber 11, but in the droplet forming apparatus 10, since the atmosphere opening portion 111 is provided above the liquid chamber 11, the atmosphere opening portion 111 is provided. The bubbles mixed in the cell solution 300 can be discharged to the outside air through the air opening portion 111. This makes it possible to continuously and stably form the droplet 310 without discarding a large amount of liquid for discharging bubbles.

That is, when air bubbles are mixed in the vicinity of the nozzle 121 or when a large number of air bubbles are mixed in the membrane 12, the ejection state is affected. Therefore, in order to stably form the droplets for a long time, it is necessary. It is necessary to discharge the mixed air bubbles. Normally, the air bubbles mixed on the membrane 12 move upward naturally or by the vibration of the membrane 12, but since the liquid chamber 11 is provided with the air opening portion 111, the mixed air bubbles are moved from the air opening unit 111. It can be discharged.

The membrane 12 may be vibrated at a timing when the droplets are not formed within a range where the droplets are not formed, and the bubbles may be positively moved above the liquid chamber 11.

As described above, since the droplet forming apparatus 10 according to the first embodiment has the atmosphere opening portion 111 that opens the inside of the liquid chamber 11 to the atmosphere, the atmosphere opening portion even if air bubbles are mixed in the liquid chamber 11. Bubbles can be discharged to the outside air through 111. Therefore, unlike an inkjet head having a normal pressurized liquid chamber, it is possible to prevent non-ejection even if air bubbles are mixed in the liquid chamber 11, and the droplet 310 can be continuously and stably formed. Can be done.

<Modification 1 of the first embodiment>
In the first modification of the first embodiment, an example of a droplet forming apparatus including a liquid supply means and a liquid amount detecting means is shown. In the first modification of the first embodiment, the description of the same component as that of the above-described embodiment may be omitted.

FIG. 4 is a cross-sectional view (No. 1) illustrating the droplet forming apparatus according to the first modification of the first embodiment, and shows an example of the droplet forming apparatus provided with the liquid supply means. With reference to FIG. 4, the droplet forming apparatus 10A is configured to be able to directly supply the liquid 320 (the liquid that collects in the liquid chamber 11 and becomes the cell solution 300) from the atmosphere opening portion 111 by the micropipette 14. As a result, a very small amount (for example, about 10 μl) of the cell solution 300 can be directly supplied to the droplet forming apparatus 10A, and the rare solution can be effectively used.

However, the liquid supply means is not limited to the micropipette 14, and a syringe, tube, or the like may be used. Further, the user can manually supply the liquid 320 as appropriate, or it can be combined with a system that automatically supplies the liquid 320. The micropipette 14, the syringe, and the tube are typical examples of the liquid supply means according to the present invention.

When automatically supplying the liquid, for example, the droplet forming apparatus may be provided with a liquid amount detecting means for detecting the liquid amount of the held cell solution 300, and the liquid may be supplied according to the position of the liquid level. it can. Further, the number of times the droplets are ejected may be counted, and the liquid may be automatically supplied when the ejection operation is performed more than a predetermined number of times.

FIG. 5 is a cross-sectional view (No. 2) illustrating the droplet forming apparatus according to the first modification of the first embodiment, and shows an example of the droplet forming apparatus provided with the liquid amount detecting means. In the droplet forming apparatus 10B shown in FIG. 5, a plurality of electrodes 15 are provided in the depth direction of the inner wall surface of the liquid chamber 11. Since the cell solution 300 is generally an aqueous solution containing a salt, it has high conductivity, and the amount of the cell solution 300 can be detected by examining the continuity or resistance value between the plurality of electrodes 15.

FIG. 6 is a cross-sectional view (No. 3) illustrating the droplet forming apparatus according to the first modification of the first embodiment, and shows another example of the droplet forming apparatus provided with the liquid amount detecting means. There is. In the droplet forming apparatus 10C shown in FIG. 6, a light emitting element 16 and a position sensor 17 which are liquid amount detecting means are provided above the liquid chamber 11.

The position sensor 17 is arranged at a position where light emitted from the light emitting element 16 and specularly reflected by the liquid surface 300A or the liquid surface 300B of the cell solution 300 can be received. Thereby, the distance from the position of the light received by the position sensor 17 to the liquid surface of the cell solution 300 can be calculated based on the principle of triangulation. The signal of the position sensor 17 can be converted into the amount of the cell solution 300 based on a preset conversion formula or a look-up table.

As described above, the droplet forming apparatus 10A according to the first modification of the first embodiment has a liquid supply means for directly supplying the liquid 320 from the air opening portion 111 to the liquid chamber 11. As a result, the cell solution 300 can be supplied to the liquid chamber 11 in a required amount when necessary, and droplets can be formed in a small amount. This is very important for the droplet forming apparatus 10A, which handles the cells 350, which are generally not easily available in large quantities, are very expensive, and cannot be retained inside the liquid chamber 11 for a long time. That's what it is.

Further, the droplet forming devices 10B and 10C according to the first modification of the first embodiment have liquid amount detecting means for detecting the liquid amount of the cell solution 300. This makes it possible to automatically supply the liquid according to the position of the liquid level of the cell solution 300 and automatically supply the liquid according to the number of times the droplets are ejected, improving the convenience of the user. it can.

<Modification 2 of the first embodiment>
Modification 2 of the first embodiment shows an example of a droplet forming apparatus provided with means for preventing the cell solution from drying out. In the second modification of the first embodiment, the description of the same component as that of the above-described embodiment may be omitted.

As described above, the discharge of air bubbles is important for the stable discharge of the cell solution 300, but since cells are generally vulnerable to drying, a means for preventing the cell solution from drying is provided. That is also important. The cell solution 300 may contain a salt in the solvent to adjust the osmotic pressure with the inside of the cell, and the cell may be an animal cell partitioned by a cell membrane. In some cases, special attention should be paid to drying.

In the droplet forming apparatus 10 (see FIG. 1), since the cell solution 300 held in the liquid chamber 11 is in contact with the outside air, water evaporates from the contact interface to the outside air. Due to water evaporation, a region with low water content is locally formed, and intracellular water outflow occurs due to cell drying and aggregation, or improvement of salt concentration. Therefore, it is desired that the material is in contact with the outside air from the viewpoint of discharging air bubbles, but on the other hand, there is a desire to suppress the evaporation of water to the outside air.

Further, the droplet forming apparatus 10 may be used in bio-research, and in that case, it is a problem that bacteria, cells, viruses, other proteins and the like are mixed in the cell solution 300 from the outside. Therefore, it is preferable to minimize contact with the outside air in order to prevent contamination from the outside. Therefore, each droplet forming apparatus according to the present embodiment is provided with means for preventing the cell solution from drying.

FIG. 7 is a cross-sectional view illustrating the droplet forming apparatus according to the second modification of the first embodiment, and shows an example of the droplet forming apparatus provided with the drying prevention means. With reference to FIG. 7A, in the droplet forming apparatus 10D, the upper lid 18 is provided above the liquid chamber 11. A through hole 181 is formed in the upper lid 18 to communicate the air opening portion 111 with the atmosphere. The through hole 181 is a hole having a smaller cross-sectional area than the liquid chamber 11.

By providing the upper lid 18 on which the through hole 181 is formed above the liquid chamber 11, the area of the portion of the air opening portion 111 that communicates with the atmosphere is reduced. Therefore, the humidity immediately above the cell solution 300 can be kept higher than that of the outside air, and the evaporation of water can be minimized.

By the way, in the droplet forming apparatus 10A shown in FIG. 4, when the liquid 320 is automatically or manually supplied using the micropipette 14, there is a concern that a problem may occur if the tip position of the micropipette 14 is not determined. For example, liquid splattering due to the position of the micropipette 14 being too high, damage to the membrane 12 due to the position of the micropipette 14 being too low, and the like.

As shown in FIG. 7B, in the droplet forming apparatus 10D, by pushing the micropipette 14 through the through hole 181 formed in the upper lid 18, the tip of the micropipette 14 is always in a substantially constant position. .. As a result, it is possible to prevent the liquid from splashing and damage to the membrane 12 due to the variation in the tip position of the micropipette 14. In this case, it is preferable that the shape of the through hole 181 is designed according to the shape of the micropipette 14 used by the user.

As described above, in the droplet forming apparatus 10D according to the second modification of the first embodiment, the upper lid 18 is provided above the liquid chamber 11. The upper lid 18 is formed with a hole having a cross-sectional area smaller than that of the liquid chamber 11 that allows the air opening portion 111 to communicate with the atmosphere.

As a result, the amount of water evaporation in the liquid chamber 11 is minimized, and the salt concentration becomes high at the gas-liquid interface in the liquid chamber 11 due to drying, and the outflow of water from the cells 350 is suppressed. The damage given to 350 can be reduced. That is, the activity of the cell 350 is reduced by drying the water from the cell solution 300, and the concern that the cell 350 will die can be reduced.

The light emitting element 16 and the position sensor 17 shown in the first modification of the first embodiment may be provided on the lower surface side (inside the liquid chamber 11) of the upper lid 18. As a result, the effect of preventing drying by the upper lid 18 can be obtained, and the amount of the cell solution 300 can be detected.

<Modification 3 of the first embodiment>
In the third modification of the first embodiment, an example of a droplet forming apparatus provided with an opening / closing mechanism for opening / closing an open portion to the atmosphere in order to prevent the cell solution from drying is shown. In addition, in the modification 3 of the first embodiment, the description of the same component as the already described embodiment may be omitted.

In order to avoid the problem due to the drying of the cell solution, the droplet forming apparatus according to the second modification of the first embodiment is provided with the anti-drying means, but the atmosphere is open to the atmosphere in the open portion of the droplet forming apparatus. It is more preferable that an opening / closing mechanism capable of opening / closing the communication is provided.

FIG. 8 is a cross-sectional view (No. 1) illustrating the droplet forming apparatus according to the third modification of the first embodiment, and shows an example of the droplet forming apparatus provided with an opening / closing mechanism. With reference to FIG. 8, in the droplet forming apparatus 10E, an opening / closing mechanism 19 is further installed on the upper lid 18. The form of the opening / closing mechanism 19 is not particularly limited, but for example, a mechanism for opening / closing the atmosphere opening portion 111 by sliding the plate in the arrow A direction (lateral direction) through the slide guide formed on the upper lid 18. it can.

By providing the opening / closing mechanism 19, the air opening portion 111 is opened only when the liquid is supplied, and at other times, the air opening portion 111 is closed to dry the moisture in the normal state (when forming the droplet 310). It can be minimized. Furthermore, it is possible to minimize the contamination of the cell solution 300 with bacteria, cells, viruses and the like from the outside.

By the way, it is preferable that the inside of the droplet forming apparatus is not completely sealed by the opening / closing mechanism. If the inside of the droplet forming apparatus is completely sealed, there may be a difference between the atmospheric pressure inside the droplet forming apparatus and the atmospheric pressure outside due to a decrease in the amount of liquid, a temperature change, a change in the outside air pressure, or the like. If a pressure difference occurs inside and outside the droplet forming apparatus, the liquid level shape of the nozzle may change and the ejection state may change. In particular, when the inside of the droplet forming apparatus is in a negative pressure state, there is a possibility that air bubbles are likely to be entrained. Therefore, it is preferable that the inside of the droplet forming apparatus does not become a negative pressure state even when the opening / closing mechanism closes the opening portion to the atmosphere.

FIG. 9 is a cross-sectional view (No. 2) illustrating the droplet forming apparatus according to the third modification of the first embodiment, and shows another example of the droplet forming apparatus provided with an opening / closing mechanism. With reference to FIG. 9, in the droplet forming apparatus 10F, the opening / closing mechanism 20 is installed on the upper lid 18. The opening / closing mechanism 20 has a polymer film 202 held by the polymer film holding portion 201. The opening / closing mechanism 20 is configured to be slidable in the direction of arrow A (horizontal direction). The polymer film 202 is a film having low moisture permeability but high air permeability.

By providing the opening / closing mechanism 20, it is possible to keep the pressure inside and outside the droplet forming device 10F constant while minimizing the evaporation of water.

FIG. 10 is a cross-sectional view (No. 3) illustrating the droplet forming apparatus according to the modified example 3 of the first embodiment, and shows still another example of the droplet forming apparatus provided with the opening / closing mechanism. .. With reference to FIG. 10, in the droplet forming apparatus 10G, the opening / closing mechanism 21 is installed on the upper lid 18. The main body 211 of the opening / closing mechanism 21 is provided with a flow path 212 (snake line) that is bent in a narrow zigzag shape. The opening / closing mechanism 21 is configured to be slidable in the direction of arrow A (horizontal direction).

The cross-sectional area of the flow path 212 is smaller than the cross-sectional area of the liquid chamber 11 and the cross-sectional area of the through hole 181. When the opening / closing mechanism 21 is closed, the atmosphere opening portion 111 communicates with the atmosphere via the flow path 212. Then, when the opening / closing mechanism is opened, the atmosphere opening portion 111 communicates with the atmosphere without passing through the flow path 212.

By providing the opening / closing mechanism 21, the pressure inside the droplet forming device 10G can be kept uniform with the pressure of the outside air through the flow path 212. Further, since the moisture in the droplet forming apparatus 10G diffuses to the outside air through the flow path 212 over time, it is possible to suppress the evaporation of the moisture in the droplet forming apparatus 10G.

FIG. 11 is a cross-sectional view (No. 4) illustrating the droplet forming apparatus according to the third modification of the first embodiment, in which a droplet having an elaborate layer structure of a cell solution instead of providing an opening / closing mechanism is provided. An example of a forming device is shown. With reference to FIG. 11, in the droplet forming apparatus 10H, a solvent layer 400 having a specific gravity lighter than that of the cell solution 300 is formed on the upper part of the cell solution 300 held in the liquid chamber 11. In the droplet forming apparatus 10H, the upper lid 18 may be provided as needed.

As the solvent layer 400, a material that has a low affinity for water, which is the main solvent of the cell solution 300, and is almost insoluble (has no solubility) can be used. It is typically various oils, and it is particularly suitable to use a biologically-derived oil having a high biocompatibility. Further, a layer of amphipathic molecules (surfactant) may be formed in order to stabilize the interface between the cell solution 300 and the oil.

As described above, the liquid chamber 11 holds the solvent layer 400, which has a lighter specific gravity than the cell solution 300 and is not soluble in the main solvent of the cell solution 300, on the upper surface of the cell solution 300. The effect is obtained. That is, it is possible to suppress the evaporation of water in the cell solution 300, and the bubbles that have moved upward in the cell solution 300 can be discharged to the outside air as they are through the solvent layer 400.

Further, even when the cell solution 300 is supplied from the upper part, since the cell solution 300 is heavier than the solvent layer 400, the cell solution 300 passes through the layer of the solvent layer 400. Therefore, a layer of the cell solution 300 can be easily formed under the solvent layer 400.

Although the preferred embodiments and the like have been described in detail above, the embodiments are not limited to the above-described embodiments and the like, and various embodiments and the like described above are used without departing from the scope of the claims. Modifications and substitutions can be added.

For example, when the XY direction is taken in the plane of the membrane 12 when it is not deformed and the normal direction of the membrane 12 is the Z direction, the droplet forming apparatus 10 is independently set in the X direction, the Y direction, and the Z direction. A movable mechanism may be provided. This makes it possible to easily pattern cells in the XY plane and stack cells in the Z direction.

10, 10A-10H Droplet forming device 11 Liquid chamber 12 Membrane 13 Piezoelectric element 14 Micropipette 15 Electrode 16 Light emitting element 17 Position sensor 18 Top lid 19, 20, 21 Opening and closing mechanism 111 Open to the atmosphere 181 Through hole 121 Nozzle 201 Polymer film Retaining part 202 Polymer membrane 211 Main body 212 Channel 300 Cell solution 300A, 300B Liquid level 310 Droplet 320 Liquid 350 Cell 400 Solvent layer

Patent No. 2849647

Claims (6)

A liquid holding part that holds a cell solution containing cells so that the upper part communicates with the atmosphere.
A film-like member in which a nozzle is formed and the cell solution held in the liquid holding portion is vibrated to be discharged as droplets from the nozzle.
Have,
A droplet forming apparatus having an upper lid having a hole having a cross-sectional area smaller than that of the liquid holding portion formed above the liquid holding portion. The droplet forming apparatus according to claim 1, further comprising a liquid supply means for directly supplying a cell solution from above the liquid holding portion to the liquid holding portion. The droplet forming apparatus according to claim 1 or 2, wherein an opening / closing mechanism for opening / closing the upper lid or the hole is provided above the liquid holding portion. The opening / closing mechanism is provided with a bent flow path.
The cross-sectional area of the flow path is smaller than the cross-sectional area of the liquid holding portion.
When the opening / closing mechanism is closed, the upper surface of the cell solution communicates with the atmosphere through the flow path.
The droplet forming apparatus according to claim 3, wherein when the opening / closing mechanism is opened, the upper surface of the cell solution communicates with the atmosphere without passing through the flow path. A liquid holding part that holds a cell solution containing cells so that the upper part communicates with the atmosphere.
A film-like member in which a nozzle is formed and the cell solution held in the liquid holding portion is vibrated to be discharged as droplets from the nozzle.
Have,
The liquid holding portion holds a solvent layer on the upper surface of the cell solution, which has a lighter specific gravity than the cell solution and is insoluble in the main solvent of the cell solution. Forming device. The droplet forming apparatus according to any one of claims 1 to 5, further comprising a liquid amount detecting means for detecting the liquid amount of the cell solution.

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