Method for sterilizing a liquid dispensing head, and assembly of a liquid dispensing head
The method addresses liquid adhesion and dispensing failures in liquid dispensing heads by using a protective member and vapor-permeable sheet assembly during steam sterilization, ensuring effective sterilization and maintaining dispensing performance.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- CANON KK
- Filing Date
- 2022-03-10
- Publication Date
- 2026-06-01
Smart Images
Figure 0007867821000002 
Figure 0007867821000003 
Figure 0007867821000004
Abstract
Description
Technical Field
[0001] The present invention relates to a technique for steam-sterilizing a liquid discharge head that discharges a liquid.
Background Art
[0002] In recent years, a technique has been proposed in which a liquid such as a cell suspension containing cells is discharged by using a liquid discharge head provided with a discharge substrate having fine discharge ports, and a predetermined process is performed on the liquid. In a liquid discharge head used in such a technique, in order to avoid contamination of unnecessary bacteria in the discharged liquid, it is necessary to sterilize the liquid discharge head before filling the liquid into the liquid discharge head. Currently, for sterilization of instruments that handle living bodies, sterilization methods using high-pressure steam, ethylene oxide gas, gamma rays, etc., and sterilization methods using ultraviolet rays are used. Japanese Patent Application Laid-Open No. 2004-3950 discloses a technique for sterilizing a liquid discharge head that discharges a biological sample with ultraviolet rays or steam.
[0003] Generally, when sterilizing an instrument that handles living bodies with high-pressure steam, in order to maintain the sterilized state even after sterilization, the instrument is enclosed in a bag that does not allow bacteria to pass through and has a portion that allows at least a part of the steam to pass through, and the bag is placed in a sterilizer and sterilized with high-pressure steam. For example, the bag enclosing the instrument is exposed to high-pressure steam at 121°C for 15 minutes for sterilization, and then the treatment of returning to normal temperature and normal pressure is performed. After the sterilization treatment, when the inside of the sterilizer is returned to normal temperature and normal pressure, the steam generated during sterilization changes from a gas to a liquid, and condensed liquid is generated inside the high-pressure steam sterilizer and inside the bag. Therefore, usually, after the high-pressure steam sterilization process, a drying process for drying the bag containing the instrument is performed to evaporate the liquid accumulated in the bag.
Prior Art Documents
Patent Documents
[0004]
Patent Document 1
Summary of the Invention
[0005] As described above, by performing a drying process after high-pressure steam sterilization, it is possible to evaporate the liquid inside the bag. However, when the disclosers observed the surface where the discharge port of the liquid discharge head is formed (discharge port surface) with a metal microscope after the drying process, it was confirmed that there were many liquid drying marks (water ripples) formed by the drying of the attached liquid on the discharge port surface. When such liquid drying marks are formed on the discharge port surface, the hydrophilicity of the discharge port surface decreases, making it easier for the discharged liquid to adhere to the discharge port surface, and the adhered liquid may cause dispensing problems at the discharge port.
[0006] This disclosure aims to provide a technology that enables proper sterilization of a liquid dispensing head using steam while suppressing the occurrence of dispensing failures in the liquid dispensing head. [Means for solving the problem]
[0007] This disclosure relates to a method for sterilizing a liquid discharge head, comprising a discharge element substrate having a discharge port surface on which a discharge port for discharging liquid is formed, and a liquid storage section for storing liquid to be supplied to the discharge port, the method comprising: a first step of covering at least the discharge port surface of the liquid discharge head in a non-contact manner with a protective member; a second step of constructing an assembly of the liquid discharge head by housing the protective member and the liquid discharge head with a sheet member having vapor permeability in at least a portion thereof so as to block the entry of bacteria into the liquid discharge head, or by covering the opening of the protective member; and a third step of steam sterilizing the assembly. [Effects of the Invention]
[0008] According to this disclosure, it becomes possible to properly sterilize the liquid dispensing head with steam while suppressing the occurrence of dispensing failures in the liquid dispensing head. [Brief explanation of the drawing]
[0009] [Figure 1] A perspective view showing the liquid dispensing head in the embodiment. [Figure 2] A diagram showing the surrounding structure of the ejection element substrate. [Figure 3] A schematic longitudinal side view showing the configuration of the liquid dispensing head assembly in the comparative example. [Figure 4] A schematic longitudinal cross-sectional side view showing the first example of the assembly in the embodiment. [Figure 5] Figure 4 is a perspective view showing the configuration of protective and sheet members used in the liquid discharge head assembly. [Figure 6] A longitudinal cross-sectional side view showing a second and third example of the assembly in the embodiment. [Figure 7] A longitudinal cross-sectional side view and a perspective view of a protective member showing a fourth example of the assembly in the embodiment. [Figure 8] A longitudinal cross-sectional side view showing the assembly placed on the boiler with the discharge port facing upwards. [Figure 9] A flowchart showing the procedure for high-pressure steam sterilization. [Figure 10] A diagram showing liquid drying marks formed on the ejection element substrate. [Figure 11] A diagram showing the effect of liquid dispensing heads on cells depending on whether or not they have been sterilized. [Modes for carrying out the invention]
[0010] Embodiments of this disclosure will be described in detail below with reference to the drawings. This embodiment describes a method for sterilizing a liquid dispensing head used for processing liquids such as cell suspensions containing cells, and an assembly of the liquid dispensing head used when carrying out this sterilization method. In the drawings referred to in the following description, the Z direction indicates the direction of gravity, the Z1 direction indicates upward in the direction of gravity (hereinafter also simply referred to as upward), and the Z2 direction indicates downward in the direction of gravity (hereinafter also simply referred to as downward).
[0011] [First Embodiment] (Liquid dispensing head) Figure 1 is a perspective view showing an embodiment of the liquid dispensing head according to this disclosure. The liquid dispensing head 1 has a housing 3 having a liquid storage section 3a capable of containing liquid including cells, a dispensing element substrate 2 provided on the bottom surface of the housing 3, and an electrical connection section 4 that sends power and control signals to the dispensing element substrate 2. In this embodiment, a lid 5 that closes the opening of the liquid storage section 3a is provided to be removable. The liquid storage section 3a is capable of holding liquids ranging from a small amount of liquid of several tens of microliters to several tens of milliliters.
[0012] Figure 2 shows the peripheral structure of the discharge element substrate 2. Figure 2(a) is a cross-sectional view taken along line A-A in Figure 1, and Figure 2(b) is an enlarged view showing the configuration near the discharge port in the discharge element substrate 2 of Figure 2(a). The discharge element substrate 2 has a silicon substrate 21 and a discharge port forming member 22 fixed to the lower surface of the silicon substrate 21. Multiple discharge ports 6 are formed in the discharge port forming member 22. The outer surface 2a where the openings of these discharge ports 6 are formed will be referred to as the discharge port surface 2a in the following description. A flow path 7 is formed between the discharge port forming member 22 and the silicon substrate 21, communicating with each discharge port 6. The flow path 7 communicates with a liquid supply port 21a formed in the silicon substrate 21. Furthermore, the liquid supply port 21a communicates with a liquid storage section 3a inside the housing 3 via a liquid outlet 3b formed at the bottom of the housing 3. As a result, the liquid contained in the liquid storage section 3a is supplied into the flow path 7 via the liquid outlet 3b and the liquid supply port 21a. The liquid supplied into the flow path 7 is filled into the multiple discharge ports 6 formed in the discharge port forming member 22.
[0013] Further, on the silicon substrate 21, a discharge energy generating element (hereinafter referred to as a discharge element) 8 for generating discharge energy for discharging liquid from the discharge port 6 is provided. This discharge element 8 is disposed at a position facing each discharge port 6. The discharge element 8 provided in the present embodiment is constituted by an electrothermal conversion element (heater) that emits thermal energy for discharging liquid from the discharge port 6. By driving the discharge element with a drive circuit and a control circuit (not shown) to generate thermal energy, film boiling is caused in the liquid present in the flow path 7, and the liquid can be discharged from the discharge port 6 by the pressure generated at that time. The discharge port surface 2a of the discharge element substrate 2 is surface-treated so that the discharged liquid does not easily adhere thereto. For example, a treatment is performed to impart liquid repellency. This is to suppress a decrease in the discharge performance of the discharge port 6 due to the adhesion of liquid to the discharge port surface 2a. That is, when liquid adheres to the discharge port surface 2a, the discharge of the liquid from the discharge port 6 is hindered by the adhered liquid, and discharge defects such as insufficient liquid discharge and non-discharge occur. Therefore, liquid repellency is imparted to the discharge port surface 2a.
[0014] The liquid discharge head 1 can be applied to the processing of liquids such as cell sap. For example, by discharging cell sap from the liquid discharge head, it is possible to apply it to a process such as cell processing in which pores are formed in the membrane on the cell surface contained in the cell sap and a predetermined compound is introduced through the pores. However, when applying the liquid discharge head to such a process, it is essential to sterilize the liquid discharge head, and the following sterilization treatment needs to be performed. In this example, an electrothermal conversion element is used as the discharge element, but it is also possible to configure it to discharge liquid from the discharge port using an electromechanical conversion element such as a piezo. In this case as well, it is possible to process the cells contained in the liquid in the same manner as when using the electrothermal conversion element.
[0015] (Sterilization treatment) Sterilization is defined as the remaining microorganisms such as bacteria and viruses being reduced to one in a million. Currently, sterilization methods include high-pressure steam sterilization, ethylene oxide gas sterilization, gamma-ray sterilization, etc. High-pressure steam sterilization refers to coagulating proteins with the generated steam to kill microorganisms. In high-pressure steam sterilization, for example, heating at a temperature of 121 °C (pressure of atmospheric pressure + 0.1 MPa) for 15 minutes or at a temperature of 134 °C (pressure of atmospheric pressure + 0.2 MPa) for 10 minutes is cited as the sterilization conditions. The pressure during high-pressure steam sterilization treatment is preferably not less than atmospheric pressure + 0.1 MPa and not more than atmospheric pressure + 0.2 MPa.
[0016] In order to ensure high-pressure steam sterilization, the inside of the liquid discharge head 1, which is the object to be sterilized, needs to be filled with steam (saturated steam) with a humidity of 100%. Among the liquid discharge head 1, the flow path 7 communicating with the discharge port 6 has an elongated shape, so it is one of the parts that are difficult to fill with steam with a humidity of 100%. Therefore, in order to fill the flow path with steam, it is preferable that the discharge port 6 located at its end is open.
[0017] (Assembly of liquid discharge head) Here, the configuration of the assembly of the liquid discharge head used in the sterilization process of the liquid discharge head 1 will be described. In the following description, in order to clarify the characteristics of the assembly of the liquid discharge head of the present embodiment, the assembly of the liquid discharge head used in the general sterilization method of the liquid discharge head will be described as a comparative example of the present embodiment, and then the assembly of the liquid discharge head in the present embodiment will be described.
[0018] <Assembly of liquid discharge head in comparative example> Figures 3(a) and (b) are diagrams showing the configuration of the assembly 11 of the liquid discharge head in the comparative example (hereinafter also simply referred to as the assembly). The assembly 11 in the comparative example consists of the liquid discharge head 1 and the sheet member 9 that houses the liquid discharge head 1.
[0019] <<Liquid discharge head>> The liquid discharge head 1 shown in Figures 3(a) and 3(b) is the same as the liquid discharge head 1 shown in Figure 1. A discharge element substrate 2 with multiple discharge ports arranged therein is provided at the bottom of the liquid discharge head 1, and the discharge port surface 2a, which is the lower surface of the discharge element substrate 2, is treated to be hydrophobic for the liquid discharged from the discharge ports.
[0020] <<Sheet material>> The sheet member 9 blocks the entry of bacteria into the liquid dispensing head 1 after sterilization, maintaining its sterile state, and is formed in a bag shape capable of containing the liquid dispensing head 1. The sheet member 9 is made of a material that blocks the permeability of bacteria. Furthermore, at least a portion of the sheet member 9 is made of a material that is permeable to steam. Therefore, the liquid dispensing head 1 can be sterilized by placing the liquid dispensing head assembly 11 in the chamber (also called the boiler) of a sterilization device (also called an autoclave) and performing steam sterilization. After sterilization, the sterile state of the liquid dispensing head 1 can be maintained by removing the assembly 11 from the sterilization device as is. Examples of materials that do not allow bacteria or steam to pass through when used for the sheet member 9 that constitutes the assembly 11 include polyethylene film. Examples of materials that do not allow bacteria to pass through but allow steam (gas) to pass through include sterilization paper and polyethylene nonwoven fabric. To prevent the discharge port 6 of the liquid discharge head 1 from being blocked by paper dust, the material that blocks bacterial permeability and is permeable to vapor is preferably polyethylene nonwoven fabric. The vapor permeability of the vapor-permeable material is preferably 7 seconds / 100ml or more and 120 seconds / 100ml or less. The vapor permeability can be measured by the Gurley method described in JIS P 8117.
[0021] The comparative example liquid discharge head assembly 11, configured as described above, is placed in a sterilizer and subjected to high-pressure steam sterilization. Here, we will explain the case where high-pressure steam sterilization is performed with the discharge port surface 2a of the discharge element substrate 2 of the liquid discharge head 1, which is housed in a bag-shaped sheet member 9, positioned downward in the direction of gravity, as shown in Figure 3(a). When high-pressure steam sterilization is performed in this configuration, when the inside of the sterilizer is returned to room temperature and atmospheric pressure after sterilization, liquid accumulates in the lower region inside the assembly 11. This liquid includes liquid that has condensed from water vapor that was present inside the assembly 11, and liquid that has been drawn from the outside of the assembly 11 to the inside of the assembly 11 when the pressure is reduced from high pressure to atmospheric pressure. The liquid accumulated inside the assembly 11 is collected and moved by capillary force generated by the contact between the discharge element substrate 2 and the sheet member 9, and adheres to the discharge element substrate 2.
[0022] Furthermore, as shown in Figure 3(b), it is also possible to place the assembly 11 on a sterilizer with the discharge port surface 2a of the liquid discharge head 1 facing upward and perform high-pressure steam sterilization. In this case as well, liquid will accumulate in the lower region of the assembly 11 after sterilization. However, since the discharge port surface 2a of the discharge element substrate 2 of the liquid discharge head 1 is facing upward, the possibility of the liquid accumulated in the lower region of the assembly 11 coming into contact with the discharge port surface 2a is reduced. However, even in this case, liquid may adhere to the discharge port surface 2a. That is, because the sheet member 9 is soft and easily comes into contact with the discharge port surface 2a, capillary forces are generated in the area where the sheet member 9 and the discharge port surface 2a come into contact. Consequently, the liquid generated inside the assembly 11 may accumulate and move due to capillary forces and adhere to the discharge port surface 2a.
[0023] As described above, when high-pressure steam sterilization is performed using the comparative example assembly 11, there is a possibility that the liquid generated inside the assembly 11 will adhere to the discharge port surface 2a of the discharge element substrate 2. This liquid is not pure water, but contains components that have leached out from the sheet member 9 and various components constituting the liquid discharge head 1 during the high-pressure steam sterilization process. Even if materials that are less prone to leaching are selected for the sheet member 9 and the liquid discharge head 1, it is difficult to completely eliminate such leaching. Therefore, when the liquid that adhered to the discharge port surface 2a dries after high-pressure steam sterilization, the leached components contained in the liquid will adhere to it. The inventors speculate that this forms liquid drying marks (water ripples), making it easier for liquid to adhere to the discharge port surface 2a, and causing discharge failure.
[0024] <Assembly of the liquid dispensing head in this embodiment> Next, the liquid discharge head assembly in this embodiment will be described with reference to Figures 4 to 7. Figure 4(a) is a schematic longitudinal cross-sectional side view showing the assembly 11A (first example) in this embodiment. The assembly 11A in this example includes a liquid discharge head 1, a sheet member 9A that houses the liquid discharge head 1, and a protective member 10A that supports the liquid discharge head 1 from below and covers the discharge port surface 2a of the discharge element substrate 2.
[0025] Figure 5(a) is a perspective view showing the configuration of the protective member 10A used in the liquid discharge head assembly 11A shown in Figure 4(a), and Figure 5(b) is a perspective view showing the configuration of the sheet member 9A shown in Figure 4(a). The protective member 10A shown in Figure 5(a) is a hollow box shape with a housing space for housing the liquid discharge head 1, and an opening 10A1 is formed at the top. In addition, a support portion 10A2 is formed in a part of the bottom of the protective member 10A that protrudes inward to support the portion of the bottom of the liquid discharge head 1 that avoids the discharge element substrate 2.
[0026] By housing the liquid discharge head 1 through the opening 10A1 of the protective member 10A, the support portion 10A2 of the protective member 10A supports the portion of the bottom of the liquid discharge head 1 that avoids the discharge element substrate 2. This is because the protective member has more rigidity than the sheet member. As a result, the liquid discharge head 1 is held with the discharge element substrate 2 at a predetermined distance from the protective member 10A, and the discharge port surface 2a of the discharge element substrate 2 is covered by the bottom of the protective member 10A facing it, at a predetermined distance (see Figure 4(a)). The Young's modulus of the protective member is preferably 1 MPa or more and 100 MPa or less. Here, the Young's modulus can be measured according to JIS K 7127:1999. The protective member 10A has sufficient rigidity to not deform due to heat such as high-pressure steam sterilization. In particular, the softening temperature of the protective member is preferably 121°C or higher. Here, the softening temperature of the protective member can be measured according to JIS K 6863:1994. Examples of materials for protective components include polypropylene and polyethylene terephthalate. Other materials can also be used to construct protective components, as long as they do not deform significantly during steam sterilization.
[0027] The protective member 10A, which houses the liquid discharge head 1, is inserted through the opening 9A1 of a bag-shaped sheet member 9A as shown in Figure 5(b). Then, the opening 9A1 is sealed with tape or the like to seal the sheet member 9A. This completes the liquid discharge head assembly 11A shown in Figure 4(a).
[0028] Similar to the comparative example described above, the sheet member 9A is composed of a bag-shaped member that houses the liquid dispensing head 1 and the protective member 10A so that the sterile state is maintained even after the liquid dispensing head 1 has been sterilized. The sheet member 9A is made of a material that blocks the permeability of bacteria and is vapor-permeable to at least a portion of it. For this reason, in the assembly 11A, the dispensing element substrate 2 is exposed to the atmosphere. This is because at least a portion of the sheet member 9A is vapor-permeable, and the protective member 10A is kept in a non-contact state with the dispensing element substrate 2.
[0029] With the assembly 11A configured as described above, the liquid discharge head 1 can be properly sterilized by placing the liquid discharge head assembly 11A inside the sterilizer chamber and performing high-pressure steam sterilization. Furthermore, in the assembly 11A of this embodiment, it is possible to reduce the adhesion of liquid generated inside the assembly 11A to the discharge port surface 2a of the discharge element substrate 2 after high-pressure steam sterilization. That is, in the assembly 11A of this embodiment, the protective member 10A supports the liquid discharge head 1 while being separated from the discharge element substrate 2, and the sheet member 9A and the discharge port surface 2a of the discharge element substrate 2 are in a non-contact state. Therefore, even if liquid is generated inside the assembly 11A when the high-pressure steam sterilization is completed and the inside of the chamber returns to room temperature and atmospheric pressure, the adhesion of that liquid to the discharge port surface 2a of the discharge element substrate 2 is suppressed by the capillary force generated by the contact between the discharge element substrate 2 and the sheet member 9A. Thus, the adhesion of liquid to the discharge port surface 2a is greatly reduced. As a result, when the assembly 11A is in a dry state, the possibility of liquid drying marks being formed on the discharge port surface 2a of the liquid discharge head 1 is greatly reduced, and the discharge performance of the liquid discharge head is maintained in good condition.
[0030] Next, the preferred size of the sheet member 9A will be explained using Figure 4(b). In the assembly 11A shown in Figure 4(a), the protective member 10A is not fixed to the liquid discharge head 1. Therefore, it is sometimes preferable to limit the size of the bag-shaped sheet member 9A that houses the liquid discharge head 1 and the protective member 10A to a predetermined dimension or less. When the protective member 10A housing the liquid discharge head 1 is placed inside the sheet member 9A, the opening 10A1 of the protective member 10A is positioned to face the inner surface of the bag-shaped sheet member 9. In this case, it is preferable to use a sheet member 9 with dimensions such that the liquid discharge head 1 does not escape out of the opening 10A1 of the protective member 10A. That is, it is preferable to make the circumference of the inner surface of the bag-shaped sheet member 9A (length of the solid line 9A' in Figure 4(b)) smaller than the minimum circumference surrounding both members (length of the dashed line in Figure 4(b)) when the liquid discharge head 1 is not housed in the protective member 10A. By using a sheet member 9A of these dimensions, it is possible to prevent the liquid discharge head 1 from escaping from the protective member 10A covered by the sheet member 9A. In contrast, if the circumference of the inner surface of the sheet member 9A' (length of the solid line 9A') is greater than the minimum circumference surrounding the protective member 10A and the liquid discharge head 1 (length of the dashed line), as in the assembly 11A' shown in Figure 4(b), the liquid discharge head 1 may escape from the protective member 10A. When the opening 10A1 of the protective member 10A is facing upward, the liquid discharge head 1 remains supported within the protective member 10A by gravity. Therefore, the liquid discharge head 1 will not escape from the protective member 10A. However, if the opening 10A1 faces downward during transportation of the assembly 11A', there is a possibility that the liquid discharge head 1 may escape from the protective member 10A. Therefore, by setting the dimensions of the sheet member 9A to be used as described above, it is possible to prevent the liquid discharge head 1 from escaping from the protective member 10A without having to worry about the orientation of the opening 10A1 of the protective member 10A.
[0031] Furthermore, if the protective member 10A is not fixed to the liquid discharge head 1 as described above, it is also possible to construct an assembly 11B (second example) as shown in Figure 6(a). That is, the assembly 11B has a configuration in which a sheet member 9B is fixed to the opening 10A1 of the protective member 10A by heat sealing or the like. In this example as well, the sheet member 9B has the function of blocking the permeability of bacteria and is made of a material that is at least partially permeable to vapor.
[0032] Furthermore, it is also possible to construct an assembly 11C (third example) as shown in Figure 6(b), in which the protective member 10A is not fixed to the liquid dispensing head 1. This assembly 11C has a configuration in which, in addition to the liquid dispensing head 1, protective member 10A, and sheet member 9A, a lid 5 is provided at the opening of the liquid storage portion 3a of the liquid dispensing head 1. With this assembly 11C, it becomes easier to remove the sterilized liquid dispensing head 1. That is, when using the sterilized liquid dispensing head 1, the user first tears the bag-shaped sheet member 9A in the clean bench. Next, with one hand, the user takes out the protective member 10A containing the liquid dispensing head 1 and lid 5 from the torn part of the sheet member 9A, and inverts the top and bottom of the protective member 10A towards the other hand. This makes it easy to remove the liquid dispensing head 1 together with the lid 5. In this case, since the opening of the liquid storage section 3a is covered by the lid 5, the inside of the liquid storage section 3a is not contaminated, and since the user's hands do not come into contact with the discharge port surface 2a of the discharge element substrate 2, the discharge port surface 2a and the discharge port 6 are not contaminated.
[0033] The protective member 10A can also serve to protect the electrical connection. Because the protective member 10A is hollow and box-shaped, it can protect most of the liquid dispensing head, thus protecting the liquid dispensing head from damage. Furthermore, the protective member 10A can also prevent damage to the sheet member 9A by the liquid dispensing head 1.
[0034] Next, the assembly 11D (fourth example) will be described based on Figure 7. Figure 7(a) is a schematic longitudinal cross-sectional side view of the assembly 11D, and Figure 7(b) is a perspective view showing the protective member 10B used in the assembly 11D.
[0035] The liquid discharge head assembly 11D shown in Figure 7(a) comprises a liquid discharge head 1, a resin protective member 10B detachably fixed to the housing 3 which forms the outer shell of the liquid discharge head 1, and a sheet member 9A. As shown in Figure 7(b), the protective member 10B has a bent shape due to a bottom portion 10B1 and two side portions 10B2 and 10B3 rising from the bottom portion 10B1. At the upper ends of each of the two side portions 10B2 and 10B3, there are claw portions (engaging portions) 10B4 and 10B5 that protrude inward. The claw portion 10B4 can engage with a recess 3c formed on one side of the housing 3, and the claw portion 10B5 can engage with a recess 3d formed on the other side of the housing 3. By engaging these claw portions 10B4 and 10B5 with the corresponding recesses 3c and 3d of the housing 3, the protective member 10B can be detachably fixed to the housing 3.
[0036] When the protective member 10B is fixed to the housing 3, the bottom portion 10B1 of the protective member 10B functions as a covering portion that covers the ejection element substrate 2 provided at the bottom of the housing 3 with a predetermined distance between them. Since the protective member 10B is made of resin, the elasticity of the resin can release the engagement between the recesses 3c and 3d and the claw portions 10B4 and 10B5, allowing the protective member 10B to be removed from the housing 3.
[0037] After fixing the protective member 10B to the liquid discharge head 1, the assembly 11D is constructed by placing the liquid discharge head 1 inside a bag-shaped sheet member 9A and sealing the opening of the sheet member 9A. In this assembly 11D as well, the discharge port surface 2a of the discharge element substrate 2 is covered by the protective member 10B, so the sheet member 9A does not come into contact with the discharge port surface 2a. Therefore, the possibility of liquid generated inside the assembly 11B after sterilization adhering to the discharge port surface 2a is greatly reduced. This allows for proper steam sterilization while suppressing a decrease in the discharge performance of the liquid discharge head 1. Furthermore, when adopting a configuration in which the protective member 10B is fixed to the liquid discharge head 1 as in this example, the size of the bag-shaped sheet member 9A used can be freely selected as long as it is large enough to accommodate the liquid discharge head 1 with the protective member 10B fixed to it.
[0038] In the assemblies 11A to 11D described above, protective members 10A and 10B are shown as box-shaped or bent in shape, but the shape of the protective members is not limited to these. The protective members can take other shapes as long as they can cover the discharge port surface 2a of the discharge element substrate 2 without contacting it. For example, the discharge port surface 2a may be covered in a non-contact manner by a flat protective member. Alternatively, rib-shaped protrusions can be provided on the side or bottom surface inside the box-shaped protective member, and a part of the liquid discharge head (excluding the discharge element substrate) can be hooked onto these protrusions, thereby covering the discharge port surface of the discharge element substrate in a non-contact manner with the bottom surface of the protective member. Furthermore, the shape, structure, and material of the protective members can be appropriately selected in consideration of usage conditions, applications, lifespan, cost, etc.
[0039] Furthermore, when using a sterilized liquid dispensing head, the protective member may be configured in a shape that makes it easy to remove the liquid dispensing head from the protective member. For example, in the case of a hollow box-shaped protective member, the protective member may be configured such that a space is formed between the protective member and the liquid dispensing head into which a finger can be inserted, making it easier to grasp the liquid dispensing head with a finger.
[0040] <Sterilization method> Next, a method for steam sterilization of the liquid discharge head in the assembly described above will be explained. In this embodiment, high-pressure steam sterilization is performed using water vapor as the steam sterilization process. The object to be sterilized (in this example, the liquid discharge head assembly) is placed in the chamber of a sterilization device that enables this high-pressure steam sterilization process, and the door of the sterilization device is closed to close the chamber. Water vapor is generated inside the chamber, or water vapor is introduced into the chamber from the outside to create a high temperature and high pressure inside the chamber. In addition, there are high-pressure steam sterilization devices that reduce the amount of air inside the chamber using a vacuum pump and introduce water vapor into the chamber. After sterilizing the object to be sterilized by keeping the inside of the chamber at a high temperature and high pressure for a certain period of time, it is returned to room temperature and atmospheric pressure. Methods for returning the inside of the chamber to room temperature and atmospheric pressure include exhaust and natural heat dissipation, as well as forcibly exhausting from the chamber using a vacuum pump or forcibly lowering the temperature by spraying water from the top of the chamber.
[0041] In methods that forcibly return to room temperature and pressure, the temperature inside the assembly drops rapidly, creating negative pressure inside the assembly. This can cause liquid outside the assembly to pass through the sterile paper of the sheet material and penetrate the inside of the assembly. Similarly, when forcibly evacuating using a vacuum pump, the pressure reduction caused by the evacuation causes a rapid drop in temperature, and water vapor condenses, generating liquid inside the assembly.
[0042] Afterward, the assembled parts placed inside the sterilizer are dried. Some high-pressure steam sterilizers can perform both sterilization and drying processes. Alternatively, after high-pressure steam sterilization, the sterilized items (assemblies) can be removed from the sterilizer and dried in a dryer.
[0043] As described above, the liquid discharge head is sterilized by first assembling the liquid discharge head assemblies 11A to 11D, and then placing the assemblies 11A to 11D into a high-pressure steam sterilizer for sterilization. In this embodiment, the protective member 10A or 10B can prevent contact between the discharge port surface 2a of the discharge element substrate 2 and the sheet member 9A or 9B. Therefore, the accumulation and movement of liquid on the discharge port surface 2a can be prevented by capillary force between the discharge port surface 2a of the discharge element substrate 2 and the sheet member 9A or 9B, and the possibility of liquid adhering to the discharge port surface 2a is greatly reduced.
[0044] Depending on the steam sterilization conditions (temperature, pressure, and cooling means), liquid is likely to form inside the assembly placed in the chamber. Therefore, as shown in Figures 8(a) and (b), it is preferable to place the assemblies 11A and 11B in the chamber of the high-pressure steam sterilizer so that the discharge port surface 2a of the discharge element substrate 2 faces upward. Here, "upward" refers to a direction in which, when the assembly is placed, the direction in which liquid is discharged from the discharge port 6 of the discharge element substrate 2 (liquid discharge direction) is within the range from the horizontal to directly upward (vertically upward). It also refers to a direction in which, when the assembly is placed, the liquid discharge direction is within the range from the horizontal to directly downward (vertically downward). Note that although Figures 8(a) and (b) only show assemblies 11A and 11B, it is also preferable to place the other assemblies 11C and 11D in the chamber with the discharge port surface 2a facing upward. By arranging the discharge port surface 2a facing upward in this way, the possibility of liquid adhering to the discharge port surface 2a can be further reduced.
[0045] As described above, the liquid discharge head assembly in this embodiment makes it possible to reduce the adhesion of liquid to the discharge port surface 2a of the discharge element substrate 2, even when high-pressure steam sterilization is performed as the sterilization method. However, the assemblies 11A to 11D in this embodiment are effective not only for high-pressure steam sterilization but also for other sterilization methods. For example, the assemblies 11A to 11D in this embodiment are also effective when using a sterilization method in which gas is used during sterilization and liquid is generated after sterilization is completed. In any sterilization method, by using the assemblies 11A to 11D in this embodiment, it is possible to properly sterilize the discharge port and fine structural parts such as the flow path communicating therewith, while reducing the adhesion of liquid to the discharge port surface 2a of the discharge element substrate 2.
[0046] Furthermore, during sterilization, instead of placing the items to be sterilized inside a sheet material, the items are sometimes placed directly into the sterilization chamber and sterilized using high-pressure steam sterilization. In this case as well, in order to maintain the sterilization status of the sterilized items, it is necessary to remove the items from the chamber and seal them in sterilized bags. However, in order to seal the sterilized items while maintaining their sterilization status, the handling of the items must be done with the utmost care, which is time-consuming and costly.
[0047] Another method considered involves pre-applying tape or similar material to the discharge port surface of the discharge element substrate of the liquid discharge head, placing the liquid discharge head in a sheet material, and then sterilizing it with high-pressure steam. However, while the discharge port of the liquid discharge head is fine, the flow path that supplies liquid to the discharge port is long in the depth direction. As a result, the flow path is one of the parts that is difficult for steam to reach. Therefore, if the inflow of steam from the discharge port is completely blocked with tape or similar material, although the adhesion of liquid to the discharge port surface can be avoided, the entry point for steam into the flow path will be limited to one side, the side where the liquid is filled. As a result, it becomes difficult for steam to reach the entire flow path, and the sterilization state of the liquid discharge head will be compromised.
[0048] In this embodiment, since the discharge port is not sealed, it is possible to introduce steam from the opening side of the discharge port, allowing steam to reach the entire flow path and enabling a good sterilization state to be achieved.
[0049] <Sterilization process> Here, the processing procedure for performing high-pressure steam sterilization using the liquid discharge head assembly of this embodiment will be explained based on the flowchart in Figure 9. In the flowchart in Figure 9, the letter S attached to each processing number indicates a step (process).
[0050] First, the liquid dispensing head 1 is combined with a protective member 10A or 10B (S1 (first step)). When using protective member 10A, the liquid dispensing head 1 is housed inside protective member 10A. When using protective member 10B, the claws 10B4 and 10B5 of protective member 10B are engaged with the housing 3 of the liquid dispensing head 1 to fix protective member 10B to housing 3. As a result, at least the discharge port surface 2a of the discharge element substrate 2 of the liquid dispensing head 1 is covered by protective member 10A or 10B.
[0051] Next, a sheet member 9A or 9B is further added to the structure combining the liquid discharge head 1 and the protective member 10A or 10B to form one of the liquid discharge head assemblies 11A to 11D (S2 (second step)). Here, if a bag-shaped sheet member 9A is used, the structure combining the liquid discharge head 1 and the protective member 10A or 10B is sealed inside the sheet member 9A. If a sheet member 9B is used, the sheet member 9B is sealed by heat welding or the like to adhere it to the opening 10A1 of the protective member 10A. At this time, the protective members 10A and 10B are not in contact with the discharge port surface 2a of the discharge element substrate 2. The discharge element substrate 2 is also exposed to the atmosphere. However, since the liquid discharge head 1 is covered by the protective member 10A (or 10B) and the sheet member 9A (or 9B), it can maintain a sterile state even after sterilization.
[0052] Next, the liquid discharge head assemblies 11A to 11D are placed in the steam sterilizer (S3). Then, the steam sterilizer is activated and steam sterilization is performed (S4 (third step)). In this embodiment, high-pressure steam sterilization is performed. After the sterilization process is completed, the steam sterilizer is returned to room temperature and pressure (S5 (fourth step)), and the liquid discharge head assemblies 11A to 11D are dried (S5).
[0053] <Example of using a sterilized liquid dispensing head> By filling a sterilized liquid dispensing head with a pre-sterilized liquid and then dispensing it, the dispensed liquid can maintain its sterile state. For example, by filling a sterilized liquid dispensing head with a liquid used for cell culture and dispensing it towards a culture dish to which cells are attached, a cell suspension that maintains its sterile state can be placed into the culture dish. In other words, a sterilized liquid dispensing head can be used as a means of dispensing a predetermined amount of sterile liquid to a predetermined location.
[0054] By filling a sterilized liquid dispensing head with a liquid containing dispersed cells and dispensing it towards a culture dish, cells can be seeded into the culture dish. In other words, a sterilized liquid dispensing head can be used as a means of moving a predetermined amount of cells to a predetermined location.
[0055] By filling a sterilized liquid dispensing head with cells and the compound to be introduced into the cells, and then dispensing it, the compound can be introduced into the cells. In other words, a sterilized liquid dispensing head can be used as a means of introducing compounds into cells.
[0056] (Examples) The sterilization method for the liquid dispensing head shown in the above embodiment will be further explained in detail by referring to the first to sixth examples and the first and second comparative examples.
[0057] In the examples and comparative examples described below, a liquid dispensing head assembly was constructed, sterilized by high-pressure steam, and then dried. The presence of liquid drying marks (water ripples) on the dispensing element substrate was then observed, and evaluations were performed for each example and comparative example.
[0058] In this embodiment, the liquid ejection head assembly was constructed by combining two types of protective members 10A and 10B, two types of sheet members 9A and 9B, a lid 5, and a liquid ejection head 1. In the comparative example, the liquid ejection head assembly was constructed by enclosing the liquid ejection head 1 in a bag-shaped sheet member 9A. Furthermore, the temperature and time for steam sterilization, and the orientation of the ejection port surface 2a of the ejection element substrate 2 were defined as steam sterilization conditions, and the sterilization process was carried out. As the liquid ejection head 1, the liquid ejection head 1 shown in Figure 1 (manufactured by Canon Inc.) was used. This liquid ejection head 1 is an inkjet recording head used for ejecting black ink in the Canon Inc. business inkjet printer G1310.
[0059] Table 1 shows the configuration of the assemblies in each embodiment and comparative example, the conditions for steam sterilization, and the evaluation results for each embodiment.
[0060] The protective member 10A shown in Table 1 is the same as the protective member 10A shown in Figures 4(a) and 5(a), and refers to a box-shaped protective member (manufactured by Canon Inc.). The protective member 10B in Table 1 is the same as the protective member 10B shown in Figures 7(a) and (b), and refers to a protective member (manufactured by Canon Inc.) that can be fixed to the liquid dispensing head. The sheet member 9A in Table 1 is the same as the sheet member 9A shown in Figures 4(a) and 5(b), and refers to a bag-shaped sheet member (simple sterilization pouch, manufactured by Thermo Fisher Scientific K.K.). The sheet member 9A is made of vapor-permeable sterilization paper, polypropylene, and polyethylene terephthalate, etc. The sheet member 9A is provided with tape for closing the opening 9A1 after the object to be sterilized is placed inside. The sheet member 9B is the same as the sheet member 9B shown in Figure 6(a), and is made of a polyethylene nonwoven fabric sheet (Tyvek®: manufactured by DuPont).
[0061] In the first embodiment, the liquid dispensing head 1 was housed in a box-shaped protective member 10A. Next, the protective member 10A containing the liquid dispensing head 1 was placed inside a bag-shaped sheet member 9A. Finally, the opening 9A1 of the bag-shaped sheet member 9A was closed with tape attached to the sheet member 9A, forming the liquid dispensing head assembly 11A. The cross-sectional view of this assembly 11A is the same as that of Figure 4(a).
[0062] In the second embodiment, a protective member 10B (see Figure 7(b)) was fixed to the liquid dispensing head 1. Next, the liquid dispensing head 1 with the protective member 10B attached was placed inside a bag-shaped sheet member 9A. Finally, the opening 9A1 of the bag-shaped sheet member 9A was closed with the tape attached to the sheet member 9A to form the liquid dispensing head assembly 11D. The cross-sectional view of this assembly 11D is the same as that of Figure 7(a).
[0063] In the third, fourth, and fifth embodiments, the liquid dispensing head 1 was housed in a box-shaped protective member 10A, and the opening in the housing 3 of the liquid dispensing head 1 was covered with a lid 5. Next, the protective member 10A, which housed the liquid dispensing head 1 and the lid 5, was placed inside a bag-shaped sheet member 9A. Finally, the opening 9A1 of the bag-shaped sheet member 9A was closed with tape attached to the sheet member 9A to form the liquid dispensing head assembly 11C. The cross-sectional view of this assembly is the same as that of Figure 6(b).
[0064] In the sixth embodiment, the liquid dispensing head 1 and the lid 5 were placed inside a box-shaped protective member 10A. Next, a sheet member 9B was placed over the opening of the box-shaped protective member 10A, and the sheet member 9B was fixed to the protective member A by heat welding to form the liquid dispensing head assembly. In other words, the opening of the protective member is covered by the sheet member in this assembly. The cross-sectional view of this assembly is the same as that of Figure 6(a), except that the lid 5 is not shown.
[0065] In the first and second comparative examples, the liquid dispensing head was placed in a bag-shaped sheet member 9A, and the opening 9A1 of the bag-shaped sheet member 9A was closed with tape attached to the sheet member 9A to form the liquid dispensing head assembly 11. The cross-sectional view of this assembly is the same as that shown in Figure 3(a). Note that the sheet member 9 shown in Figures 3(a) and (b) is the same as the bag-shaped sheet member 9A shown in Figure 5.
[0066] Next, the assemblies of the 1st to 6th embodiments and the 1st and 2nd comparative examples were steam-sterilized using a steam sterilizer (MX-500 (manufactured by Tommy Seikou Co., Ltd.)). The steam sterilization conditions for each embodiment and comparative example are as shown in Table 1. When performing steam sterilization, the assemblies were placed in a basket and then placed inside the steam sterilizer. The assemblies were placed so that the discharge port surface 2a of the discharge element substrate 2 was facing downward or upward in the direction of gravity. Specifically, in the 1st to 4th embodiments, the 6th embodiment, and the 2nd comparative example, the assemblies were placed so that the discharge port surface 2a was facing upward, while in the 5th embodiment and the 1st comparative example, the assemblies were placed so that the discharge port surface 2a was facing downward.
[0067] Furthermore, steam sterilization was performed using a steam sterilizer at a temperature of 121°C for 20 minutes or at a temperature of 134°C for 15 minutes. Specifically, in the first to third examples, the sixth example, the first comparative example, and the second comparative example, the steam sterilization was set to 121°C for 20 minutes, while in the fourth and fifth examples, it was set to 134°C for 15 minutes.
[0068] After the steam sterilizer indicated the completion of sterilization, the basket was removed from the steam sterilizer. The assembled body was placed in the basket and then placed in a dryer, where it was dried at 60°C for at least 4 hours. After drying, the liquid discharge head 1 was removed from the assembled body. The discharge port surface 2a of the discharge element substrate 2 was observed using a metallurgical microscope to check for the presence or absence of liquid drying marks. Based on the presence or absence of liquid drying marks, a classification was made as follows: ○: no liquid drying marks, △: very slight liquid drying marks, ×: many liquid drying marks, and this was used as the evaluation result.
[0069] [Table 1]
[0070] The components of the assembly used in the above sterilization process are as follows: Liquid dispensing head: Approximately 50 x 30 x 30 mm (manufactured by Canon Inc.) Lid: Manufactured by Canon Inc. Protective component 10A: Approximately 60 x 35 x 40 mm (manufactured by Canon Inc.) Protective component 10B: Manufactured by Canon Inc. Sheet component 9A: Bag-shaped sheet (simple sterilization pouch, approximately 130 x 250 mm (manufactured by Thermo Fisher Scientific Co., Ltd.)), Sheet component 9B: Nonwoven fabric sheet (Tyvek (manufactured by DuPont)) In the assembly 11A, the hollow box-shaped protective member 10A can support the liquid discharge head 1 by a support portion 10A2 provided at its bottom. Therefore, even when the liquid discharge head 1 was housed in the protective member 10A, the discharge element substrate 2 and the protective member 10A did not come into contact. The outer dimensions of the liquid discharge head 1 were approximately 50 × 30 × 30 mm, the outer dimensions of the protective member 10A were approximately 60 × 35 × 40 mm, and the dimensions of the bag-shaped sheet member 9A were approximately 130 × 250 mm. As a result, after housing the protective member 10A containing the liquid discharge head 1 in the sheet member 9A, the opening 9A1 of the sheet member 9A could be sealed with the attached tape. Furthermore, because the bag-shaped sheet member 9A covered the protective member 10A containing the liquid discharge head 1, the liquid discharge head 1 could not escape from the hollow box-shaped protective member 10A, and the state in which the liquid discharge head 1 was housed in the protective member 10A could be maintained. The bag-shaped sheet component 9A is equipped with an indicator that changes color when steam sterilized. After steam sterilization, it was confirmed that the sheet component had changed color.
[0071] In the first and second comparative examples, as shown in Figure 10, liquid drying marks Lm formed by the drying of liquid adhering to the discharge element substrate 2 were observed on the discharge port surface of the discharge element substrate 2. In the fifth example, some liquid drying marks were observed, but the frequency of occurrence was lower compared to the first and second comparative examples, and even when liquid drying marks occurred, the affected area was small, and it was not severe enough to cause liquid head discharge failure. No liquid drying marks were observed in the first to fourth examples and the sixth example. As described above, it has become clear that the occurrence of liquid drying marks on the discharge port surface 2a can be reduced by using protective members 10A and 10B.
[0072] Next, to confirm whether the liquid dispensing head had been properly sterilized by high-pressure steam sterilization, a biological indicator for steam sterilization (H3723T (Fukuzawa Shoji Co., Ltd.)) was used. In order to confirm the sterilization status using this biological indicator, when assembling the liquid dispensing head assembly, the biological indicator was placed in the liquid storage section 3a of the housing 3 beforehand, and the opening of the liquid storage section 3a was sealed with a lid 5. The lid 5 was fixed to the liquid storage section 3a by welding.
[0073] Next, the liquid discharge head 1 was housed in a protective member 10A, and the protective member 10A was placed in a bag-shaped sheet member 9A (manufactured by DuPont Ltd.). The opening 9A1 of the sheet member 9A was then closed by heat welding to form the assembly 11C. The cross-sectional view of the assembly 11C is the same as in Figure 6(b). The assembly 11C was placed in a steam sterilizer with the discharge port surface 2a of the discharge element substrate 2 facing upwards, and steam sterilization was performed at a temperature of 134°C for 15 minutes. After sterilization, the steam sterilization biological indicator was removed without performing a drying process and heated to 56°C. After 48 hours, the change in color of the steam sterilization biological indicator was used to confirm whether sterilization had been achieved. Note that 56°C is a suitable temperature for bacterial culture, and 48 hours is the time required to culture the bacteria. If bacteria are still present after the water sterilization treatment, those bacteria will be cultured, and the color of the biological indicator will change.
[0074] After 48 hours, the color of the biological indicator for steam sterilization was checked, and it showed that the biological indicator was purple, indicating that sterilization had been achieved. In the assembly 11C used to confirm the sterilization status, the opening of the liquid storage section 3a of the liquid discharge head 1 was sealed with a lid 5, and the inlet for water vapor into the flow path 7 was restricted to the outlet 6. Therefore, if the color of the biological indicator in the liquid storage section 3a changes as described above after steam sterilization, it proves that water vapor was able to flow in from the outlet 6, pass through the flow path 7, and fill the liquid storage section 3a. In other words, it proves that the liquid storage section 3a, liquid outlet 3b, liquid supply port 21a, flow path 7, and discharge port 6 have been sterilized. In this example, since the color of the biological indicator changed to purple, it became clear that the discharge port 6 and flow path 7, which are the most difficult parts of the liquid discharge head to sterilize, were properly sterilized.
[0075] Next, it was confirmed whether the sterilized liquid discharge head maintained proper discharge performance. First, the liquid discharge head 1 was placed in the protective member 10A. Next, the protective member 10A containing the liquid discharge head 1 was placed in a bag-shaped sheet member 9A, and the opening 9A1 of the sheet member 9A was closed to form an assembly. The cross-sectional view of the assembly is the same as in Figure 4(a). This assembly 11A was placed in a steam sterilizer with the discharge port surface 2a of the discharge element substrate 2 facing upwards, and steam sterilization was performed at a temperature of 134°C for 15 minutes. After sterilization was completed, while maintaining the discharge port surface 2a facing upwards, the assembly was moved from the steam sterilizer to a dryer and dried at a temperature of 60°C for more than 4 hours. The liquid discharge head 1 was removed from the assembly 11A, and the discharge port surface 2a of the discharge element substrate 2 was observed with a metallurgical microscope. Furthermore, a liquid (black ink (product name: GI-390BK), manufactured by Canon Inc.) was filled into the liquid ejection head, and the liquid was ejected using a liquid ejection device (inkjet printer (product name: G1310), manufactured by Canon Inc.).
[0076] No cracks or peeling were observed on the discharge element substrate 2 of the sterilized liquid discharge head 1. Furthermore, no liquid drying marks or foreign matter were found on the discharge element substrate 2. When liquid was discharged using the liquid discharge device, sterilized liquid was discharged. Liquid was discharged from almost all of the discharge ports 6 formed on the discharge element substrate 2. From these results, it became clear that when the liquid discharge head 1 is steam-sterilized using the assembly 11A with the protective member 10A, the occurrence of liquid drying marks on the discharge port surface 2a of the discharge element substrate 2 can be suppressed, thereby preventing discharge failures. In other words, the liquid discharge head was able to maintain proper discharge performance even after high-pressure steam sterilization.
[0077] [Second Embodiment] In this embodiment, we describe a configuration in which the dispensing device is used as a compound introduction device for introducing a compound into cells. The liquid dispensing head 1 is filled with a liquid containing the compound and the cells into which the compound is introduced. In this embodiment, this liquid is called a cell suspension (also called a cell-containing liquid). The liquid dispensing head 1 may also be called a cell processing head. The cell suspension dispensed from the liquid dispensing head 1 contains cells into which the compound has been introduced. In the following description, the compound to be introduced into cells is also referred to as the "target compound".
[0078] <Target Compounds> The compound to be introduced can be appropriately selected according to the purpose. Examples of compounds that can be introduced include nucleic acids, proteins, or labeling substances. However, the compound is not limited to these examples as long as it is small enough to be encapsulated within the target cell. However, from the viewpoint of minimizing damage to cells, the size of the compound is preferably one-fifth or less of the average diameter of the cell, and more preferably one-tenth or less. Typical compounds that can be applied in this embodiment include nucleic acids such as DNA or RNA.
[0079] <Cell type> The cells handled in this embodiment include adherent cells, suspension cells, spheroids (aggregated cells), etc. The average diameter of the cells is such that they can be discharged from the discharge port, for example, between 1 μm and 100 μm.
[0080] <Cell suspension> A cell suspension comprises at least one target compound and at least one target cell, and is primarily composed of water. In this invention, the cell suspension is a state in which cells are dispersed in a liquid. The cells in the cell suspension only need to be in a state where they can be dispersed in the liquid by stirring, and may settle in the liquid when left standing. Furthermore, it is preferable to include other components as appropriate to enable cell survival during and after the introduction process.
[0081] <Water and water-soluble organic solvents> The cell suspension used in this embodiment can be an aqueous liquid medium containing water or a mixture of water and a water-soluble organic solvent. A cell suspension can be obtained by adding cells and the target compound to the aqueous liquid medium.
[0082] <Compound introduction method> In the compound introduction method of this embodiment, cells cultured by adherent culture or suspension culture are separated into individual cells or small cell clumps by the action of enzymes, etc. Then, using a centrifuge or the like, only the cells are allowed to settle using the difference in specific gravity. After that, the supernatant medium other than the cells is removed, and then a medium containing the target compound is added and mixed using a pipette or stirrer to prepare a cell suspension.
[0083] Large cell clumps are removed by passing the prepared cell suspension through a cell strainer with a diameter similar to the minimum channel diameter in the liquid dispensing head 1. The prepared cell suspension is then introduced into the liquid dispensing head 1 using a micropipette or similar tool. If the cell suspension smoothly fills the outlet 6 of the liquid dispensing head 1 due to wetting by surface tension, the introduction operation is performed immediately after filling. If the cell suspension does not reach the outlet 6 of the liquid dispensing head 1, filling can be achieved by aspirating from the outlet 6 using a suction mechanism or an external suction pump. Alternatively, filling can be achieved by pressurizing the liquid storage section 3a that stores the cell suspension using an external pressure pump.
[0084] Subsequently, the compound is introduced into the cells by driving the discharge energy generating element (discharge element) in the liquid discharge head 1. Then, the cell suspension is discharged from the discharge port 6 into the substrate or culture medium. The target compound is introduced into the discharged cells.
[0085] The following shows the results of an investigation into whether there is any difference in the performance of introducing compounds into cells using liquid dispensing heads with and without sterilization treatment.
[0086] The liquid dispensing head 1 and lid 5 were housed in a protective member 10A, and the protective member 10A was placed in a bag-shaped sheet member 9A (manufactured by DuPont Ltd.). The opening of the sheet member 9A was then closed by heat welding to form the assembly 11C. Steam sterilization was performed at a temperature of 126°C for 15 minutes. After sterilization was complete, it was allowed to air dry.
[0087] Cells derived from Chinese hamster ovaries (CHO-K1, Cellular Engineering Technologies) were detached from the culture dish using trypsin. After centrifugation, the supernatant was removed and the cells were dispersed in Ham's F-12 Nutrient Mix (F-12, Thermo Scientific Co., Ltd.). Fluorescein isothiocyanate-dextran (FITC-Dex, molecular weight 70k, Sigma-Aldrich LLC), a fluorescently labeled dextran, was dissolved in phosphate-buffered saline (PBS) at a concentration of 10 mg / ml. The CHO-K1 cells and FITC-Dex solutions were mixed to create a CHO-K1 cell concentration of 2.0 × 10⁶. 6 A solution with cells / ml and a FITC-Dex concentration of 0.5 mg / ml was prepared. The prepared solution was filled into either a sterile or non-sterilized liquid dispensing head. The filled solution was dispensed into a culture dish (glass-based dish, manufactured by AGC Techno Glass Co., Ltd.) using a liquid dispensing device. The cells were observed using a phase-contrast microscope. Subsequently, F-12 medium containing 10% fetal bovine serum (FBS) and 1% penicillin streptomycin was added, and the cells were observed again using a phase-contrast microscope. After incubation for 2 hours at 37°C in a 5% CO2 environment, the cells were detached using trypsin and centrifuged. After removing the supernatant, the cells were redispersed in PBS containing 2% FBS. The amount of FITC-Dex introduced into CHO-K1 cells was measured using a cell sorter (BD FACSMelody cell sorter, manufactured by Becton Dickinson Japan Co., Ltd.). The cell sorter was measured using a 488nm laser capable of detecting FITC, a 507LP mirror, and a 527 / 32 filter. The cell distribution was then gated and analyzed from the forward and side scattering data.
[0088] Phase-contrast microscopy revealed that cells were dispensed from both sterile and non-sterilized liquid dispensing heads. After adding F-12 medium, phase-contrast microscopy observation showed a high proportion of brightly glowing cells from both dispensing heads. Figure 11 shows the results of cell sorting analysis. The horizontal axis represents the FITC intensity ratio, and the vertical axis represents the count histogram. There was no significant difference in the amount of FITC-Dex taken up by CHO-K1 cells between sterile and non-sterilized heads. The sterile liquid dispensing heads maintained their ability to deliver compounds to cells for introduction.
[0089] [Other embodiments] In the above embodiment, an example was shown in which a liquid dispensing head that performs steam sterilization is used to dispense a cell suspension. However, this disclosure is also valid for liquid dispensing heads that dispense liquids that require sterilization during dispensing. [Explanation of symbols]
[0090] 1. Liquid dispensing head 2a Discharge port surface 3a Liquid storage section 6 Outlet 9A, 9B Sheet members 10A, 10B Protective components 11A~11D assembly S1 1st process S2 2nd process S4 3rd process
Claims
1. A method for sterilizing a liquid dispensing head comprising a dispensing element substrate having a dispensing port surface formed on which a liquid dispensing port is formed, and a liquid storage section for storing the liquid supplied to the dispensing port, A first step involves covering at least the discharge port surface of the liquid discharge head with a protective member in a non-contact manner, A second step involves arranging the protective member and the liquid dispensing head in such a way that the protective member and the liquid dispensing head are contained by a sheet member having vapor permeability in at least a portion thereof, thereby blocking the entry of bacteria into the liquid dispensing head, or by covering the opening of the protective member to constitute the liquid dispensing head assembly, A third step involves steam sterilizing the assembly, A method for sterilizing a liquid dispensing head, characterized by comprising the following features.
2. The method for sterilizing a liquid dispensing head according to claim 1, characterized in that the protective member has higher rigidity than the sheet member.
3. The method for sterilizing a liquid dispensing head according to claim 1 or 2, characterized in that the sheet member is in the shape of a bag capable of accommodating the liquid dispensing head and the protective member.
4. The method for sterilizing a liquid dispensing head according to any one of claims 1 to 3, characterized in that the protective member has a hollow box shape that can accommodate the liquid dispensing head and has an opening formed therein that allows the liquid dispensing head to be inserted into and removed, and covers the discharge port surface of the liquid dispensing head housed inside the protective member with a predetermined distance between them.
5. The method for sterilizing a liquid dispensing head according to claim 4, characterized in that the protective member has a bottom portion that covers the discharge port surface of the liquid dispensing head housed in the protective member, and a support portion that supports the liquid dispensing head in a state where the bottom portion is spaced apart from the discharge port surface.
6. The method for sterilizing a liquid dispensing head according to any one of claims 3 to 5, characterized in that the sheet member has a circumference that prevents the liquid dispensing head from escaping from the opening of the protective member.
7. The method for sterilizing a liquid dispensing head according to any one of claims 4 to 6, characterized in that the sheet member is fixed to the protective member so as to cover the opening.
8. The method for sterilizing a liquid dispensing head according to any one of claims 1 to 3, characterized in that the protective member has an engaging portion that can engage with the liquid dispensing head, is detachably fixed to the liquid dispensing head by the engaging portion, and has a covering portion that covers the discharge port surface when fixed to the liquid dispensing head.
9. A method for sterilizing a liquid dispensing head according to any one of claims 1 to 8, characterized in that the assembly is positioned so that the discharge port surface faces upward, and the assembly is subjected to steam sterilization.
10. A method for sterilizing a liquid dispensing head according to any one of claims 1 to 8, characterized in that the assembly is positioned so that the discharge port surface faces downward, and the assembly is subjected to steam sterilization.
11. The method for sterilizing a liquid dispensing head according to any one of claims 1 to 10, characterized in that the assembly includes a lid that removably closes the opening formed in the liquid storage portion.
12. The method for sterilizing a liquid dispensing head according to any one of claims 1 to 11, characterized in that the steam sterilization is water steam sterilization.
13. The method for sterilizing a liquid dispensing head according to any one of claims 1 to 12, characterized in that the steam sterilization is high-pressure steam sterilization.
14. A method for sterilizing a liquid dispensing head according to any one of claims 1 to 13, further comprising a fourth step of cooling the steam-sterilized assembly.
15. A method for sterilizing a liquid dispensing head according to any one of claims 1 to 14, characterized in that the sheet member is in a non-contact state with the dispensing port surface.
16. A liquid discharge head comprising a discharge element substrate having a discharge port surface formed with a discharge port for discharging liquid, and a liquid storage section for storing the liquid supplied to the discharge port, A protective member that covers at least the discharge port surface of the liquid discharge head in a non-contact manner, A sheet member which has vapor permeability in at least part and which houses the protective member and the liquid dispensing head to block the entry of bacteria into the liquid dispensing head, or which covers the opening of the protective member, A liquid dispensing head assembly characterized by comprising the following:
17. The liquid dispensing head assembly according to claim 16, characterized in that the protective member has higher rigidity than the sheet member.
18. The liquid dispensing head assembly according to claim 16 or 17, characterized in that the sheet member is in the shape of a bag capable of accommodating the liquid dispensing head and the protective member.
19. The liquid discharge head assembly according to any one of claims 16 to 18, characterized in that the protective member has a hollow box shape that can accommodate the liquid discharge head and has an opening formed therein that allows the liquid discharge head to be inserted into and removed, and covers the discharge port surface of the liquid discharge head housed inside the protective member with a predetermined distance between them.
20. The liquid discharge head assembly according to any one of claims 16 to 18, characterized in that the protective member has an engaging portion that can engage with the liquid discharge head, is detachably fixed to the liquid discharge head by the engaging portion, and has a covering portion that covers the discharge port surface when fixed to the liquid discharge head.
21. The liquid dispensing head assembly according to any one of claims 16 to 20, characterized in that the liquid dispensing head dispenses cells.
22. The liquid dispensing head assembly according to any one of claims 16 to 21, characterized in that the liquid dispensing head dispenses cells and compounds and introduces the compounds into the cells.