JP7237333B2 - Droplet generation method and droplet generation device - Google Patents

Description

The present invention relates to a droplet generation method and a droplet generation device.

Conventionally, various techniques have been proposed for generating minute droplets. For example, Patent Literature 1 discloses a technique for generating minute liquid columns by periodically splitting a liquid column ejected from a nozzle by applying periodic vibration to the liquid column.

International publication WO2016/170951

However, conventionally, the actual situation is that no effective proposal has been made for forming droplets at desired positions.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a droplet generating method and a droplet generating apparatus capable of forming a droplet at a desired position.

A droplet generation method according to an aspect of the present invention includes:
holding the liquid between the first end surface of the first member and the second end surface of the second member;
connecting the geometric center of a first area surrounded by a first contact line of the liquid in contact with the first end surface and the geometric center of a second area surrounded by a second contact line of the liquid in contact with the second end surface; The liquid is broken so that a droplet is formed at the midpoint of the line segment.

In the droplet generation method,
The first region and the second region may have the same shape.

In the droplet generation method,
The first end surface and the second end surface have the same shape,
The first region is the entire region of the first end surface,
The second region may be the entire region of the second end surface.

In the droplet generation method,
A third region of the first end face having better wettability than other regions of the first end face and a fourth region of the second end face having better wettability than other regions of the second end face are the same. is the shape,
The first region is the same as the third region,
The second area may be the same as the fourth area.

In the droplet generation method,
A first central axis of the first region passing through the geometric center of the first region and perpendicular to the first end face is a second axis of the second region passing through the geometric center of the second region and perpendicular to the second end face. It may coincide with the central axis.

In the droplet generation method,
By moving the first member and/or the second member such that the first contact line does not move on the first end face and the second contact line does not move on the second end face , the liquid may be broken.

In the droplet generation method,
The liquid may be broken by moving the first member and/or the second member such that the first end surface and the second end surface are separated from each other.

In the droplet generation method,
Both the first member and the second member may be moved so that the midpoint does not move.

In the droplet generation method,
The first member and the second member may be columnar bodies having the same shape.

In the droplet generation method,
The liquid may be broken with the middle point aligned with the capturing position of the capturing means.

In the droplet generation method,
The liquid is broken while the midpoint is aligned with the focal point of the laser beam, the sound pressure node of the ultrasonic sound field, or between the electrodes that apply voltage to the liquid, as the capture position of the capture means. You may let

A droplet generating device according to an aspect of the present invention includes
a first member having a first end face;
a second member having a second end surface capable of holding liquid between itself and the first end surface;
connecting the geometric center of a first area surrounded by a first contact line of the liquid in contact with the first end surface and the geometric center of a second area surrounded by a second contact line of the liquid in contact with the second end surface; a breaker for breaking the liquid held between the first end surface and the second end surface so that a droplet is formed at the midpoint of the line segment.

According to the present invention, droplets can be formed at desired positions.

1 shows a droplet generating device according to a first embodiment; FIG. FIG. 4 is a diagram showing a liquid supply process in an operation example of the droplet generating device according to the first embodiment; FIG. 10 is a diagram showing a liquid holding process in an operation example of the droplet generating device according to the first embodiment; FIG. 10 is a diagram showing a moving process of the first member and the second member in the operation example of the droplet generating device according to the first embodiment; FIG. 10 is a diagram showing a liquid breaking process in an operation example of the droplet generating device according to the first embodiment; FIG. 10 is a diagram showing a moving step of the second member in the operation example of the droplet generating device according to the second embodiment; FIG. 11 shows a droplet generating device according to a third embodiment; FIG. 10 is a diagram showing a liquid holding process in an operation example of the droplet generating device according to the fourth embodiment; FIG. 10 is a diagram showing a moving process of the first member and the second member in the operation example of the droplet generating device according to the fourth embodiment; FIG. 10 is a diagram showing a liquid breaking process in an operation example of the droplet generating device according to the fourth embodiment; FIG. 11 shows a droplet generating device according to a fifth embodiment;

Embodiments of the present invention will be described below with reference to the drawings. In addition, in the drawings attached to this specification, for the convenience of easy understanding of the drawings, there are cases where the reduced scale, vertical and horizontal dimension ratios, etc. are changed and exaggerated from those of the actual ones.

In addition, terms such as "perpendicular" and "identical" used in this specification to specify shapes and geometric conditions and their degree are not bound by a strict meaning, and have similar functions. Interpretation should include the range of expectations.

In addition, terms such as “hydrophilic” and “hydrophobic” that specify the degree of wettability of the member surface used in this specification assume that the liquid is “water”. However, the liquid is not limited to water and can be oil or other substances. The term "hydrophilic" is used to represent the ability to be easily wetted by a liquid, and the term "hydrophobic" is used to represent the property that is not easily wetted by a liquid.

(First embodiment)
FIG. 1 is a diagram showing a droplet generating device 1 according to a first embodiment. The droplet generator 1 includes a first member 2, a second member 3, and a breaking portion 4. As shown in FIG.

The first member 2 has a first end face 21 . In the example of FIG. 1, the first member 2 is a columnar body, and the first end surface 21 is a circular surface provided at one end of the columnar body. The entire surface of the first end surface 21 is hydrophilic. In order to make the entire surface of the first end surface 21 hydrophilic, for example, the entire first member 2 may be made of a hydrophilic material such as stainless steel, or the first member 2 other than the first end surface 21 may be made of a hydrophilic material such as stainless steel. may be formed of a hydrophobic material, and only the first end surface 21 may be formed of a hydrophilic material by coating or the like.

The second member 3 has a second end surface 31 capable of holding the bridging liquid LIB between itself and the first end surface 21 . The bridging liquid LIB contains, for example, water as a main component. In the example of FIG. 1, the second member 3 is a cylindrical columnar body, and the second end surface 31 is a circular surface provided at one end of the columnar body on the first end surface 21 side. That is, the second member 3 is a columnar body having the same shape as the first member 2 . The second end surface 31 has hydrophilicity over its entire surface. In order to make the entire surface of the second end surface 31 hydrophilic, for example, the entire second member 3 may be made of a hydrophilic material such as stainless steel, or the second member 3 other than the second end surface 31 may be made of a hydrophilic material such as stainless steel. may be formed of a hydrophobic material, and only the second end surface 31 may be formed of a hydrophilic material by coating or the like.

In the broken portion 4, a droplet is formed at the midpoint P of a line segment L connecting the geometric center C1 of the first area A1 of the first end surface 21 and the geometric center C2 of the second area A2 of the second end surface 31. , the bridging liquid LIB held between the first end surface 21 and the second end surface 31 is broken.

Here, the first area A1 is an area on the first end surface 21 surrounded by the first contact lines CL1 of the bridging liquid LIB in contact with the first end surface 21 . The second area A2 is an area on the second end face 31 surrounded by the second contact lines CL2 of the bridging liquid LIB that contacts the second end face 31 .

In the example shown in FIG. 1, the breaking portion 4 moves both the first member 2 and the second member 3 in opposite directions indicated by the arrows in FIG. Actuator to move.

Since the droplet is formed at the midpoint P, the first area A1 and the second area A2 have the same shape. More specifically, in the example of FIG. 1, the first end face 21 and the second end face 31 have the same shape, the first region A1 is the entire region of the first end face 21, and the second region A2 is the second end face 21. It is the entire area of the end surface 31 . Although the first end surface 21 and the second end surface 31 are circular in this embodiment, they may be other shapes (for example, oval or polygonal).

In order to form a droplet at the midpoint P with higher positional accuracy, the first central axis of the first area A1 passing through the geometric center C1 of the first area A1 and orthogonal to the first end surface 21 is aligned with the geometric center of the second area A2. It coincides with the second central axis of the second region A2 passing through the center C2 and orthogonal to the second end surface 31 . In the example of FIG. 1, the first central axis and the second central axis are aligned with the line segment L. As shown in FIG.

Furthermore, in order to form the droplet at the midpoint P with higher positional accuracy, the breaking portion 4 has the first contact line CL1 that does not move on the first end surface 21 and the second contact line CL2 that is located on the second end surface. The bridging liquid LIB is broken by moving the first member 2 and the second member 3 so as not to move on 31 . For example, the breaking portion 4 moves the first member 2 and the second member 3 along the central axis direction so that the first contact line CL1 does not move on the first end surface 21 and the second contact line CL2 is prevented from moving on the second end face 31. - 特許庁

Next, an operation example of the droplet generating device 1 of FIG. 1 will be described. FIG. 2 is a diagram showing a supply process of the liquid LI in an operation example of the droplet generating device 1 according to the first embodiment.

First, as shown in FIG. 2, the liquid supply device 6 supplies the liquid LI between the first end surface 21 and the second end surface 31 . The liquid supply device 6 is, for example, a micropipette and a drive device for the micropipette. For example, the liquid LI is supplied to either the first end surface 21 or the second end surface 31 in a state in which the first member 2 and the second member 3 are separated in the central axis direction of the end surfaces 21 and 31 by the breaking portion 4. This is done so that the liquid LI adheres to one side.

FIG. 3 is a diagram showing a holding process of the bridging liquid LIB in the operation example of the droplet generating device 1 according to the first embodiment. After the liquid LI is supplied between the first end surface 21 and the second end surface 31, the first end surface 21 and the second end surface 31 are aligned with the central axes of the first end surface 21 and the second end surface 31 by the breaker 4. The first member 2 and the second member 3 are moved so that the second end surface 31 is close to the first member 2 and the second member 3 . Then, when the first member 2 and the second member 3 move to a position where the liquid LI contacts both the first end face 21 and the second end face 31, as shown in FIG. The liquid LI wets and spreads over the entire surface of the end surface 31 , and the bridging liquid LIB is held between the first end surface 21 and the second end surface 31 . That is, a liquid bridge is formed between the first end face 21 and the second end face 31 .

At this time, the first contact line CL1 of the bridging liquid LIB in contact with the first end surface 21 coincides with the outer peripheral edge of the first end surface 21 because the bridging liquid LIB is wetted and spread over the entire surface of the first end surface 21 . . That is, the first area A1 of the first end face 21 surrounded by the first contact line CL1 coincides with the entire area of the first end face 21 . In addition, since the bridging liquid LIB spreads over the entire surface of the second end surface 31 , the second contact line CL2 of the bridging liquid LIB in contact with the second end surface 31 coincides with the outer peripheral edge of the second end surface 31 . In other words, the second area A2 of the second end surface 31 surrounded by the second contact line CL2 matches the entire area of the second end surface 31 .

At this time, as shown in FIG. 3, the area of the cross section of the bridging liquid LIB perpendicular to the central axis direction of the end faces 21 and 31 is maximum at the positions of the first end face 21 and the second end face 31, and It is minimum at the P position.

FIG. 4 is a diagram showing a moving process of the first member 2 and the second member 3 in the operation example of the droplet generating device 1 according to the first embodiment.

After holding the bridging liquid LIB between the first end surface 21 and the second end surface 31, as shown in FIG. 2 and the second member 3 are moved along the central axis direction of the first end surface 21 and the second end surface 31 . At this time, the breaking part 4 moves, for example, the first member 2 and the second member 3 at the same speed. In this case, the position of the midpoint P does not change during the process of moving the first member 2 and the second member 3, and remains at the position where the droplet D is to be formed.

As the first member 2 and the second member 3 move, the bridging liquid LIB held between the first end surface 21 and the second end surface 31 moves in the central axis direction of the first end surface 21 and the second end surface 31. Stretched. At this time, the first contact line CL1 of the bridging liquid LIB is pinned to the outer peripheral edge of the first end surface 21 and does not move, and the second contact line CL2 of the bridging liquid LIB is located at the outer peripheral edge of the second end surface 31. is pinned to and does not move. That is, the area of the cross-section of the bridging liquid LIB perpendicular to the central axis direction of the end faces 21 and 31 does not change at the positions of the first end face 21 and the second end face 31, and decreases at other positions.

FIG. 5 is a diagram showing a breaking step of the bridging liquid LIB in the operation example of the droplet generating device 1 according to the first embodiment.

When the distance between the first end face 21 and the second end face 31 reaches a predetermined distance by moving the first member 2 and the second member 3 in opposite directions, the distance between the first end face 21 and the second end face 31 A rupture (bridge rupture) of the bridging liquid LIB held at .

As shown in FIG. 5, a droplet D is formed at the midpoint P by breaking the bridging liquid LIB. In the examples of FIGS. 3 to 5, the first member 2 and the second member 3 are spaced apart while the central axis of the first end surface 21 and the central axis of the second end surface 31 are aligned. The first member 2 and the second member 3 may be separated with the central axis of the first end face 21 and the central axis of the second end face 31 shifted.

As described above, according to the first embodiment, the droplet D is formed at the desired position by breaking the bridging liquid LIB so that the droplet D is formed at the preliminarily intended midpoint P. be able to.

Further, according to the first embodiment, by holding the bridging liquid LIB between the entire area of the first end surface 21 and the entire area of the second end surface 31 having the same shape as the first end surface 21, a simple method can be used. , the droplet D can be formed at the midpoint P with high positional accuracy.

Further, according to the first embodiment, by aligning the first central axis of the first end surface 21 and the second central axis of the second end surface 31, the liquid droplet D can be positioned at the midpoint P with higher positional accuracy. can be formed.

Further, according to the first embodiment, by breaking the bridging liquid LIB without moving the first contact line CL1 and the second contact line CL2, the droplet D is formed at the midpoint P with higher positional accuracy. can do.

Further, according to the first embodiment, by moving both the first member 2 and the second member 3 in the direction in which the first end surface 21 and the second end surface 31 are separated so that the midpoint P does not move, , the droplet D can be formed at the midpoint P with higher positional accuracy. Also, the volume of the droplet D can be easily controlled.

(Second embodiment)
Next, a second embodiment will be described. The second embodiment differs from the first embodiment in that only one of the first member 2 and the second member 3 is moved in the moving step. FIG. 6 is a diagram showing the moving process of the second member 3 in the operation example of the droplet generating device 1 according to the second embodiment.

In the first embodiment, both the first member 2 and the second member 3 are moved so that the midpoint P does not move. In contrast, in the second embodiment, the breaking portion 4 stretches the bridging liquid LIB held between the first end surface 21 and the second end surface 31 by moving only the second member 3 . As the bridging liquid LIB is stretched, the midpoint P moves in the moving direction of the second member 3 .

Then, as in the first embodiment, when the distance between the first end surface 21 and the second end surface 31 reaches a predetermined distance, the bridging liquid held between the first end surface 21 and the second end surface 31 A droplet D is formed at the midpoint P by breaking the LIB.

According to the second embodiment, by moving only the second member 3, the structure of the breaking portion 4 (that is, the actuator) is reduced compared to the case where both the first member 2 and the second member 3 are moved. can be simplified.

(Third embodiment)
Next, a third embodiment in which the bridging liquid LIB is held between the hydrophilic region of the first end face 21 and the hydrophilic region of the second end face 31 will be described. FIG. 7 is a diagram showing a droplet generating device 1 according to a third embodiment. In the first embodiment, the bridging liquid LIB is held between the entire surface of the first end surface 21 and the entire surface of the second end surface 31 . In contrast, in the third embodiment, the bridging liquid LIB is held between the hydrophilic region of the first end face 21 and the hydrophilic region of the second end face 31 .

Specifically, the first end face 21 has a hydrophilic third region A3. In the example of FIG. 7, the third area A3 is a circular area of a predetermined range on the center side of the first end surface 21 . The first end surface 21 outside the third area A3 is hydrophobic. The third region A3 can be formed, for example, by partially coating the first end face 21 of the first member 2 made of a hydrophobic material with a hydrophilic material.

Further, the second end surface 31 has a hydrophilic fourth area A4. In the example of FIG. 7, the fourth area A4 is a circular area of a predetermined range on the center side of the second end surface 31 . The second end surface 31 outside the fourth area A4 is hydrophobic. The fourth area A4 can be formed, for example, by partially coating the second end face 31 of the second member 3 made of a hydrophobic material with a hydrophilic material.

The third area A3 and the fourth area A4 have the same shape. Although the third area A3 and the fourth area A4 are circular in this embodiment, they may be other shapes (for example, oval or polygonal).

In the third embodiment, the first member 2 and the second end face 21 are spaced apart from each other while the bridging liquid LIB is held between the third region A3 and the fourth region A4. By moving the two members 3, when the distance between the first end face 21 and the second end face 31 reaches a predetermined distance, the bridging liquid LIB held between the third region A3 and the fourth region A4 is broken and a droplet D is formed at the midpoint P.

According to the third embodiment, the hydrophilic third area A3 is provided on the first end surface 21, the hydrophilic fourth area A4 is provided on the second end surface 31, and the third area A3 and the fourth area A4 are provided. By breaking the bridging liquid LIB held between, the droplet D is formed at a desired position with high positional accuracy while relaxing the restrictions on the shape and size of the first end surface 21 and the second end surface 31. be able to.

(Fourth embodiment)
Next, a fourth embodiment will be described in which the bridging liquid LIB is broken while the midpoint P is aligned with the focal point of the laser beam. FIG. 8 is a diagram showing a holding process of the bridging liquid LIB in an operation example of the droplet generating device 1 according to the fourth embodiment. FIG. 9 is a diagram showing a moving process of the first member 2 and the second member 3 in an operation example of the droplet generating device 1 according to the fourth embodiment. FIG. 10 is a diagram showing a breaking step of the bridging liquid LIB in an operation example of the droplet generating device 1 according to the fourth embodiment.

As shown in FIGS. 8 to 10, the droplet generating device 1 according to the fourth embodiment further has a laser irradiation device 6 for irradiating laser light La, in addition to the configuration of the first embodiment.

As shown in FIG. 8, the broken portion 4 is bridged between the first end surface 21 and the second end surface 31 in a state where the midpoint P coincides with the focal point of the laser beam La emitted from the laser irradiation device 6. Holds liquid LIB.

Next, as shown in FIG. 9, the fractured portion 4 is formed into the first member 2 and the first member 2 and the second end surface 31 so that the first end surface 21 and the second end surface 31 are separated from each other with the midpoint P aligned with the focal point of the laser beam La. The second member 3 is moved in the opposite direction.

Then, as shown in FIG. 10, when the distance between the first end surface 21 and the second end surface 31 reaches a predetermined distance, the bridging liquid LIB is added in a state in which the midpoint P coincides with the focal point of the laser beam La. A droplet D is formed at the midpoint P by breaking. A droplet D formed at the midpoint P is held by the laser beam La.

According to the fourth embodiment, by focusing the laser beam La on the midpoint P, the bridging liquid LIB formed at the midpoint P can be stably held at the midpoint P by the laser beam La. .

Further, according to the fourth embodiment, droplets can be captured by the conventional optical tweezers method, or by the acoustic trap method or electrostatic levitation method in which droplets are captured using a sound field or electrostatic force instead of laser light. In comparison, droplets can be captured efficiently with high accuracy. In the fourth embodiment, the droplet D is held by breaking the bridging liquid LIB with the midpoint P aligned with the focal point of the laser beam La as the trapping position of the trapping means. The present invention is not limited to such an aspect, and the droplet D may be held using a method other than the optical tweezers method, such as an acoustic trap method or an electrostatic levitation method. When the acoustic trapping method is used, the droplet D is held by breaking the bridging liquid LIB in a state in which the midpoint P coincides with the node of the sound pressure of the ultrasonic sound field as the trapping position of the trapping means. When the electrostatic levitation method is used, the liquid droplet D is retained by breaking the bridging liquid LIB in a state where the middle point P is aligned between the electrodes that apply a voltage to the bridging liquid LIB as the capturing position of the capturing means. . In the electrostatic floating method, by controlling the voltage applied between the electrodes, the charged droplets D can be floated and held between the electrodes.

(Fifth embodiment)
Next, a fifth embodiment in which the first member 2 and the second member 3 are plate-shaped members will be described. FIG. 11 is a diagram showing a droplet generating device 1 according to a fifth embodiment. In the first embodiment, the first member 2 and the second member 3 are columnar bodies. In contrast, the first member 2 and the second member 3 in the fifth embodiment are plate-like bodies.

Similar to FIG. 7, a hydrophilic third area A3 is provided on the first end face 21, and a hydrophilic fourth area A4 is provided on the second end face 31. As shown in FIG.

According to the fifth embodiment, the droplet D can be appropriately formed at the midpoint P while relaxing restrictions on the shape and size of the first member 2 and the second member 3 .

In addition, in the embodiment described above, an actuator for moving the first member 2 and the second member 3 is exemplified as the breaking portion 4 . The fracture portion 4 is not limited to an actuator, and may be a heater that heats the first end surface 21 and the second end surface 31, for example. Alternatively, the breaking portion 4 may be a vibrator that vibrates the first end face 21 and the second end face 31 . Even in these cases, it is possible to form the droplet D at the midpoint P by evaporating or vibrating the bridging liquid LIB to break it.

The embodiment described above is merely an example and does not limit the scope of the invention. Various modifications can be made to the above-described embodiments without departing from the scope of the invention. Modified embodiments are included in the scope of the invention described in the claims and equivalents thereof.

1 Droplet generating device 2 First member 21 First end surface 3 Second member 31 Second end surface 4 Broken portion

Claims (10)

holding the liquid between the first end surface of the first member and the second end surface of the second member;
A geometric center of a first area surrounded by a first contact line of the liquid in contact with the first end face and a second area surrounded by a second contact line of the liquid in contact with the second end face by the fracture portion. and a droplet generation method for breaking the liquid so that a droplet is formed at the midpoint of a line segment connecting
The first member and the second member are configured such that a first central axis of the first region passing through the geometric center of the first region and perpendicular to the first end face passes through the geometric center of the second region and is the second member. In a positional relationship coinciding with the second central axis of the second region orthogonal to the two end faces,
the first region and the second region have the same shape, size, and wettability with the liquid;
By moving the first member and the second member in mutually opposite directions so that the first end surface and the second end surface are separated from each other by the breakage portion, the first end surface is prevented from moving such that the midpoint is not moved. A droplet generation method wherein both the member and the second member are moved to break the liquid at the midpoint. The first end surface and the second end surface have the same shape,
The first region is the entire region of the first end surface,
2. The droplet generation method according to claim 1 , wherein the second area is the entire area of the second end surface. The first region is a third region on the first end face that has higher wettability than other regions on the first end face, and the second region has wettability that is higher than the other regions on the second end face. is a fourth region in the second end face with a good
2. The droplet generation method according to claim 1 , wherein the third area and the fourth area have the same shape, size, and wettability . The breaking portion moves the first member and the second member so that the first contact line does not move on the first end surface and the second contact line does not move on the second end surface. 4. The droplet generation method according to any one of claims 1 to 3 , wherein the liquid is broken by causing the liquid to break. 5. The droplet generation method according to claim 1, wherein the liquid is broken by moving the first member and the second member in opposite directions at the same speed by the breaker. 6. The droplet generation method according to claim 5 , wherein the breaking portion is an actuator that moves the first member and the second member in mutually opposite directions so that the first end surface and the second end surface are separated from each other. . The droplet generation method according to any one of claims 1 to 6 , wherein the first member and the second member are columnar bodies having the same shape. The droplet generation method according to any one of claims 1 to 7 , wherein the breaker breaks the liquid with the middle point aligned with the capture position of the capture means. With the broken portion, the midpoint is aligned with the focal point of the laser beam, the sound pressure node of the ultrasonic sound field, or between the electrodes that apply voltage to the liquid, as the capturing position of the capturing means. 9. The method of claim 8 , wherein the liquid is broken. a first member having a first end face;
a second member having a second end surface capable of holding liquid between itself and the first end surface;
connecting the geometric center of a first area surrounded by a first contact line of the liquid in contact with the first end surface and the geometric center of a second area surrounded by a second contact line of the liquid in contact with the second end surface; a breaker that breaks the liquid held between the first end face and the second end face so that a droplet is formed at the midpoint of the line segment;
The first member and the second member are configured such that a first central axis of the first region passing through the geometric center of the first region and perpendicular to the first end face passes through the geometric center of the second region and is the second member. In a positional relationship coinciding with the second central axis of the second region orthogonal to the two end faces,
the first region and the second region have the same shape, size, and wettability with the liquid;
The breaking portion moves the first member and the second member in directions opposite to each other so that the first end surface and the second end surface are separated from each other, thereby preventing the midpoint from moving. A droplet generator, wherein both the member and the second member are moved to break the liquid.

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