Patent Publication Number: US-2021162190-A1

Title: Drug solution administration method

Description:
The present application is based on, and claims priority from JP Application Serial Number 2019-215079, filed on Nov. 28, 2019, the disclosure of which is hereby incorporated by reference herein in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a drug solution administration method. 
     2. Related Art 
     Heretofore, various methods for administering a drug solution to a target site such as an affected area have been used. As a representative method, an injection method for administering a drug solution inside a target site using a syringe and an injection needle is exemplified. Further, as disclosed in JP-A-2000-185106 (Patent Document 1), a method for administering a drug solution by ejecting a drug solution to a target site using an inkjet ejection device is also disclosed. 
     However, the injection method for administering a drug solution to a target site using a syringe and an injection needle sometimes causes pain to a patient, and also has an adverse effect that the patient may contract an infectious disease, or the like. Further, by a method for ejecting a drug solution to a target site using an inkjet ejection device in a related art as disclosed in Patent Document 1, the drug solution sometimes does not sufficiently penetrate inside from the surface of the target site depending on the type of the drug solution to be used. 
     SUMMARY 
     A drug solution administration method according to the present disclosure for solving the above problem is a drug solution administration method using an inkjet device including an inkjet head that ejects a drug solution, and a controller that controls the ejection of the drug solution from the inkjet head, wherein the drug solution is made to pierce a target site and is administered to the target site by ejecting the drug solution from the inkjet head so that a diameter of the drug solution when it is ejected from the inkjet head is 20 μm or more and 200 μm or less and an ejection rate of the drug solution when it is ejected from the inkjet head is 30 m/s or more under control of the controller. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view showing a drug solution administration unit of a first embodiment capable of implementing a drug solution administration method according to the present disclosure, and is a view showing a state where an actuator unit is set in a body portion. 
         FIG. 2  is a schematic view showing the drug solution administration unit of the first embodiment, and is a view showing a state where the actuator unit is detached from the body portion. 
         FIG. 3  is a schematic view showing the drug solution administration unit of the first embodiment, and is a view showing a state where the actuator unit is driven. 
         FIG. 4  is a view showing a state where an ejection rate of a drug solution is visually measured using the drug solution administration unit of the first embodiment. 
         FIG. 5  is a view showing a state of the inside of an ejection port when a drug solution is ejected in the drug solution administration unit of the first embodiment. 
         FIG. 6  is a schematic view showing a drug solution administration unit of a second embodiment capable of implementing a drug solution administration method according to the present disclosure, and is a view showing a state where a power supply unit is detached from a body portion. 
         FIG. 7  is a schematic view showing a drug solution administration unit of a third embodiment capable of implementing a drug solution administration method according to the present disclosure, and is a view showing a state where an actuator unit is set in a body portion. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     First, the present disclosure will be schematically described. 
     A drug solution administration method according to a first aspect of the present disclosure for solving the above problem is a drug solution administration method using an inkjet device including an inkjet head that ejects a drug solution, and a controller that controls the ejection of the drug solution from the inkjet head, wherein the drug solution is made to pierce a target site and is administered to the target site by ejecting the drug solution from the inkjet head so that a diameter of the drug solution when it is ejected from the inkjet head is 20 μm or more and 200 μm or less and an ejection rate of the drug solution when it is ejected from the inkjet head is 30 m/s or more under control of the controller. 
     According to this aspect, the drug solution is ejected so that the diameter is 20 μm or more and 200 μm or less and the ejection rate is 30 m/s or more. By administering the drug solution to the target site under such conditions, the drug solution can be administered while piercing the surface of the target site without causing a patient to feel pain, and the drug solution can be made to sufficiently penetrate into the target site. Further, by ejecting the drug solution from the inkjet head, the drug solution can be administered to the target site without bringing the other constituent members such as a needle into contact with the target site, and thus, the adverse effect can also be suppressed. 
     In the drug solution administration method according to a second aspect of the present disclosure, in the first aspect, the inkjet device includes an ejection rate measurement unit for the drug solution, and the administration of the drug solution is performed after measuring the ejection rate of the drug solution. 
     According to this aspect, the drug solution can be administered after measuring the ejection rate. The dose is sometimes restricted according to the type of the drug solution to be used, however, by adjusting the conditions so that the drug solution can pierce the target site, an accurate amount of the drug solution can be administered. 
     In the drug solution administration method according to a third aspect of the present disclosure, in the first or second aspect, the drug solution is administered while adjusting a penetration depth of the drug solution into the target site by changing the number of times of ejection of the drug solution at the same position of the target site under the control of the controller. 
     A preferred penetration depth of the drug solution into the target site varies depending on the state of the target site or the drug solution to be used. If the number of times of ejection of the drug solution at the same position of the target site is increased, the penetration depth of the drug solution into the target site is increased, however, according to this aspect, the drug solution can be administered while adjusting the penetration depth of the drug solution into the target site by a simple method in which the number of times of ejection of the drug solution at the same position of the target site is changed. 
     In the drug solution administration method according to a fourth aspect of the present disclosure, in any one of the first to third aspects, the inkjet device includes a moving mechanism for changing the position of the inkjet head, and in the administration of the drug solution, the drug solution is administered while changing the position of the inkjet head by the moving mechanism. 
     According to this aspect, the drug solution can be administered while changing the position of the inkjet head by the moving mechanism. Therefore, when the target site is located over a wide area, or the like, the drug solution can be easily administered at a preferred position. 
     In the drug solution administration method according to a fifth aspect of the present disclosure, in any one of the first to fourth aspects, the inkjet head is configured to be able to eject the drug solution with a plurality of ejection diameters under the control of the controller, and the drug solution is administered while adjusting an application range of the drug solution to the local target site by changing the ejection diameter of the drug solution under the control of the controller. 
     A preferred application range of the drug solution to the local target site varies depending on the state of the target site or the drug solution to be used. According to this aspect, the drug solution can be administered while adjusting the application range of the drug solution to the local target site by narrowing the ejection diameter of the drug solution. 
     In the drug solution administration method according to a sixth aspect of the present disclosure, in any one of the first to fifth aspects, the inkjet head is configured to be able to eject the drug solution at a plurality of ejection rates under the control of the controller, and the drug solution is administered while adjusting a penetration depth of the drug solution into the target site by changing the ejection rate of the drug solution under the control of the controller. 
     A preferred penetration depth of the drug solution into the target site varies depending on the state of the target site or the drug solution to be used. By increasing the ejection rate of the drug solution, the penetration depth of the drug solution into the target site is increased, however, according to this aspect, the drug solution can be administered while adjusting the penetration depth of the drug solution into the target site by changing the ejection rate of the drug solution. 
     In the drug solution administration method according to a seventh aspect of the present disclosure, in any one of the first to sixth aspects, the inkjet device includes an ejection distance specifying unit that specifies an ejection distance of the drug solution, which is a distance from the inkjet head to the target site, and the administration of the drug solution is performed within a range where the ejection distance is 5 mm or more and 20 mm or less by specifying the ejection distance by the ejection distance specifying unit. 
     If the ejection distance is too short, the drug solution may bounce back to the inkjet head to contaminate the inkjet head and make it unhygienic, and if the ejection distance is too long, it may become difficult for the drug solution to reach the target site at a desired ejection rate. According to this aspect, the administration of the drug solution is performed within a range where the ejection distance is 5 mm or more and 20 mm or less, and therefore, the inkjet head can be prevented from being contaminated and becoming unhygienic or the drug solution can be prevented from not reaching the target site at a desired ejection rate. 
     In the drug solution administration method according to an eighth aspect of the present disclosure, in any one of the first to seventh aspects, the inkjet head has an ejection port for ejecting the drug solution, a pressure chamber that communicates with the ejection port, an actuator that is displaced in a pressing direction and in an opposite direction to the pressing direction, and a displacement magnification mechanism for magnifying an amount of displacement and transmitting the displacement of the actuator to the pressure chamber. 
     It is difficult to eject a drug solution so that the ejection rate is 30 m/s or more using a general inkjet head. According to this aspect, the pressure chamber can be pressed with a larger amount of displacement than an amount of displacement of the actuator due to the displacement magnification mechanism, and therefore, the drug solution can be ejected so that the ejection rate is 30 m/s or more. 
     In the drug solution administration method according to a ninth aspect of the present disclosure, in the eighth aspect, the displacement magnification mechanism includes a liquid chamber in which a liquid is enclosed, a first wall portion that constitutes a part of a wall face of the liquid chamber, and that is displaced according to the displacement of the actuator so as to apply a pressure to the liquid, and a second wall portion that constitutes a part of a wall face of the liquid chamber, that has a smaller area facing the liquid than the area of the first wall portion facing the liquid, and that is displaced in the pressing direction in a state where an elastic force acting in the opposite direction is generated by a pressure of the liquid when a pressure is applied to the liquid by the displacement of the first wall portion. 
     According to this aspect, by adopting a configuration in which the liquid chamber having the first wall portion and the second wall portion is provided, a high-precision displacement magnification mechanism can be constituted. Then, by the high-precision displacement magnification mechanism, the drug solution can be ejected so that the ejection rate is 30 m/s or more with high precision. 
     In the drug solution administration method according to a tenth aspect of the present disclosure, in the eighth or ninth aspect, under the control of the controller, a surface of the drug solution formed at the ejection port is drawn toward the inside of the pressure chamber so as to form a recessed shape by displacing the actuator in the opposite direction, and a columnar shape protruding toward the outside of the pressure chamber is formed at a central portion when viewed from the ejection direction of the drug solution at the surface in the recessed shape and also the drug solution in the columnar shape is ejected by displacing the actuator in the pressing direction. 
     According to this aspect, the drug solution can be ejected so that the ejection rate is 30 m/s or more with high precision by displacing the actuator so as to once recess the surface of the drug solution formed at the ejection port, and thereafter form a columnar shape at a central portion of the recessed portion. Further, when the drug solution is ejected in a spherical shape, it is difficult to visually confirm whether or not the drug solution is ejected, however, by ejecting the drug solution in a columnar shape, it is possible to visually confirm whether or not the drug solution is ejected. 
     Hereinafter, embodiments according to the present disclosure will be described with reference to the accompanying drawings. Note that the following drawings are all schematic views, and some constituent members are omitted or shown in a simplified manner. Further, in the respective drawings, an X-axis direction is a horizontal direction, a Y-axis direction is a horizontal direction and also a direction orthogonal to the X-axis direction, and a Z-axis direction is a vertical direction. 
     First Embodiment 
     First, the entire configuration of a drug solution administration unit  1  that is an embodiment capable of implementing a drug solution administration method according to the present disclosure will be described with reference to  FIGS. 1 to 4 . As shown in  FIGS. 1 to 4 , the drug solution administration unit  1  of this embodiment has an actuator unit  2  and a body unit  3 . 
     The actuator unit  2  includes a controller  10 , an actuator holder  21 , an actuator  22 , and an abutment portion  23  other than a power supply (not shown). The actuator  22  is displaced along the Z-axis direction under the control of the controller  10 . That is, by driving the actuator  22  under the control of the controller  10 , the abutment portion  23  changes the position along the Z-axis direction with respect to the actuator holder  21 . The drug solution administration unit  1  of this embodiment includes the controller  10  in the actuator unit  2 , but may be configured to include the controller  10  in the body unit  3 . 
     The body unit  3  includes an inlet port  31  for a drug solution L 1 , a drug solution chamber  32  that communicates with the inlet port  31 , a passage  33  that communicates with the drug solution chamber  32 , a pressure chamber  34  that communicates with the passage  33 , and an ejection port  35  that communicates with the pressure chamber  34 . The members from the inlet port  31  to the ejection port  35  constitute a storage portion for the drug solution L 1 . Further, the body unit  3  includes a mounting portion  37  on which the actuator unit  2  is mounted, and a pivot portion  38  that is coupled to the mounting portion  37  through a hinge  39  and can be pivoted by pivoting the hinge  39 , which is easy to understand by comparing  FIG. 1  and FIG.  2 . The actuator unit  2  can be attached to and detached from the mounting portion  37  by pivoting the pivot portion  38  around the hinge  39  and moving the actuator unit  2  in the arrow direction in  FIG. 2 . In the drug solution chamber  32 , a urethane foam for keeping the storage portion for the drug solution L 1  at a negative pressure is placed so that the drug solution L 1  stored in the body unit  3  does not leak out from the inlet port  31  or the ejection port  35 . However, a configuration in which a self-sealing valve or the like is provided in place of the urethane foam, or the like may be adopted. 
     In the mounting portion  37 , a support portion  36  that supports the actuator holder  21  in an abutting state when mounting the actuator unit  2  is formed. Then, in a portion for mounting the actuator unit  2  of the mounting portion  37 , a displacement magnification mechanism  40  having a first wall portion  41 , a second wall portion  42 , and a liquid chamber  43 , which is sandwiched between the first wall portion  41  and the second wall portion  42  in the Z-axis direction, and in which a liquid L 2  is enclosed is provided. 
     Further, as shown in  FIGS. 1 and 2 , the drug solution administration unit  1  of this embodiment is configured to be able to attach a seal portion  11  that closes the inlet port  31  and a seal portion  12  that closes the ejection port  35  when a user does not use the drug solution administration unit  1 . However, as shown in  FIGS. 3 and 4 , when a user uses the drug solution administration unit  1 , the seal portion  11  and the seal portion  12  are detached. 
     Here, as shown in  FIGS. 1 to 4 , the drug solution administration unit  1  of this embodiment is configured to include one actuator unit  2  and one ejection port  35 . However, it is not limited to such a configuration, and for example, a configuration in which the drug solution administration unit  1  includes a plurality of actuator units  2 , one pressure chamber  34  to be used in common for the plurality of actuator units  2 , and one ejection port  35  that communicates with the pressure chamber  34 , or the like may be adopted. By adopting such a configuration, fine adjustment of the ejection amount of the drug solution L 1  from the ejection port  35  is facilitated. However, even if the drug solution administration unit  1  is configured to include one actuator unit  2  and one ejection port  35  as in this embodiment, by continuously driving the actuator  22  a plurality of times, the ejection amount of the drug solution L 1  from the ejection port  35  can be adjusted. 
     The drug solution administration unit  1  of this embodiment is configured to include the actuator unit  2  and eject the drug solution L 1  from the ejection port  35  by driving the actuator  22  of the actuator unit  2 . However, it is not limited to such a configuration. For example, an ejection portion configured to include a piston inside a nozzle having a tip with a tapered shape is used, and a so-called jet dispenser-type ejection portion that ejects the drug solution L 1  while allowing the piston to collide with the tapered portion may be used. However, a configuration in which a contactless ejection portion like the drug solution administration unit of this embodiment is used is preferred because the exchangeability is favorable and also the occurrence of impurities involved in the collision of the members can be suppressed. In the present disclosure, the jet dispenser-type ejection portion shall also be included the inkjet head. 
     According to the type of the target site, the state of the target site, or the like, various materials can be used as the drug solution L 1  without limitation. For example, other than a material constituted only by a liquid, a material containing a solid drug to be dissolved at body temperature, a material containing a solid to be used for a purpose other than treatment such as a pigment, or the like can also be used as the drug solution L 1 . As an inclusion that can be used as the drug solution L 1 , for example, water, a moisturizer, hyaluronic acid, an isotonic agent, a vaccine, serum, insulin, vitamins, an antimicrobial agent, a coloring material, a dye, a preservative, an antiallergic agent, an anticancer agent, an antihistamine, an antibiotic agent, an antipsychotic drug, narcotic drugs, an anticholinergic drug, a hair agent, oils, and the like can be used alone or in combination. In particular, it is desirable to use an inclusion having a molecular weight of about 500 or more that cannot penetrate the corneum. Further, in order to promote transdermal administration, an alcohol such as ethanol, propylene glycol, or menthol can also be used. In addition, aside from the ejection of the drug solution L 1  from the ejection port  35 , water or the like is sprayed from a place other than the ejection port  35  so as to moisturize a target site, and for example, the corneal water content is set to 15% or more, and thereafter, the drug solution L 1  may be ejected. 
     As shown in  FIGS. 1, 3, and 4 , in a state where the actuator unit  2  is mounted on the mounting portion  37 , the abutment portion  23  is in a state of being in contact with the first wall portion  41 . The first wall portion  41  and the second wall portion  42  are both constituted by a flexible member. Then, the area of the second wall portion  42  is smaller than the area of the first wall portion  41 . As shown in  FIGS. 3 and 4 , when the first wall portion  41  is pressed by the abutment portion  23 , the first wall portion  41  is deflected downward in the drawing, and since the liquid L 2  is enclosed in the liquid chamber  43 , the second wall portion  42  is also deflected downward in the drawing. Here, the area of the second wall portion  42  is smaller than the area of the first wall portion  41 , and therefore, the deflection amount in a direction along the Z-axis direction of the second wall portion  42  becomes larger than the deflection amount in a direction along the Z-axis direction of the first wall portion  41 . Therefore, the displacement magnification mechanism  40  is configured to be able to magnify the displacement of the actuator  22  and transmit the displacement to the pressure chamber  34 . 
     The drug solution administration unit  1  of this embodiment is configured to be able to move the abutment portion  23  not only downward in the drawing but also upward in the drawing by driving the actuator  22 . Then, the first wall portion  41  can be deflected upward in accordance with the upward movement of the abutment portion  23 . When the first wall portion  41  is deflected upward, the second wall portion  42  is also deflected upward. Since the drug solution administration unit  1  of this embodiment is configured in this manner, not only can a positive pressure be generated in the pressure chamber  34  by applying a pressure to the pressure chamber  34 , but also a negative pressure can be generated in the pressure chamber  34 . As a configuration in which a negative pressure can also be generated in the pressure chamber  34 , a configuration in which the abutment portion  23  is adhered to the first wall portion  41  so that also the first wall portion  41  moves in the Z-axis direction with the movement in the Z-axis direction of the abutment portion  23  can also be adopted, but a configuration in which a force is applied upward in advance so that the first wall portion  41  is biased toward the abutment portion  23  may be adopted. 
     Therefore, the drug solution administration unit  1  of this embodiment can eject the drug solution L 1  from the ejection port  35  by repeating a state where a positive or negative pressure is not applied to the pressure chamber  34  and a state where a positive pressure is applied to the pressure chamber  34 . Further, by repeating an operation of generating a negative pressure in the pressure chamber  34  and an operation of generating a positive pressure in the pressure chamber  34 , a recessed shape La is formed at the surface of the drug solution L 1  at the ejection port  35 , and thereafter, a columnar shape Lb is formed from a part of the recessed shape La as shown in  FIG. 3 , and the drug solution L 1  in the columnar shape Lb can be ejected from the ejection port  35  as shown in  FIG. 4 . 
     The ejection rate of the drug solution L 1  can be visually confirmed by ejecting the drug solution L 1  in the columnar shape Lb from the ejection port  35 , and for example as shown in  FIG. 4 , emitting strobe light  13  at a predetermined timing from the moment when the actuator  22  is driven corresponding to the moment when the drug solution L 1  is ejected from the ejection port  35  using a stroboscope having a light  14  or the like. Specifically, for example, a scale with graduations or the like is located in the vicinity of the ejection port  35 , and the strobe light  13  is emitted after a predetermined time from the moment when the actuator  22  is driven, whereby the ejection rate of the drug solution L 1  can be visually confirmed. This is because the drug solution L 1  ejected from the ejection port  35  is in the columnar shape Lb, and therefore is easily visually recognized. For example, when the strobe light  13  is emitted after 0.001 s from the moment when the actuator  22  is driven and the tip in the ejection direction of the drug solution L 1  starts to be ejected from the ejection port  35 , if the tip in the ejection direction of the drug solution L 1  is located at a position separated by a distance of 5 cm from the ejection port  35 , the ejection rate is 5 cm/0.001 s, that is, 50 m/s. Since the ejection rate of the drug solution L 1  can be visually confirmed, the ejection rate can be confirmed with a simple device configuration. 
     However, the ejection rate of the drug solution L 1  may be confirmed not visually, but by using a camera capable of capturing an image of the drug solution L 1  to be ejected from the ejection port  35  or the like. This is because by using a camera capable of capturing an image of the drug solution L 1  to be ejected from the ejection port  35  or the like, the ejection rate can be accurately confirmed. Further, since the camera can also be diverted to a camera for capturing an image of the target site, it is also possible to eject the drug solution L 1  at an accurate position. 
     Next, in the drug solution administration unit  1  of this embodiment, an operation in which the recessed shape La is formed at the surface of the drug solution L 1  at the ejection port  35 , and thereafter, the columnar shape Lb is formed from a part of the recessed shape La, and the drug solution L 1  in the columnar shape Lb is ejected from the ejection port  35  will be described with reference to  FIG. 5 . 
     When the drug solution L 1  is ejected from the ejection port  35 , first, the actuator  22  is driven so as to move the abutment portion  23  upward and deflect the first wall portion  41  upward. Then, a negative pressure is generated in the liquid chamber  43 , and therefore, the second wall portion  42  is also deflected upward. By the upward deflection of the second wall portion  42 , a negative pressure is generated in the pressure chamber  34 , and the recessed shape La is formed at the surface of the drug solution L 1  at the ejection port  35 . The leftmost state to the fifth state from the left in  FIG. 5  show a manner in which the recessed shape La is formed at the surface of the drug solution L 1  at the ejection port  35  by the upward deflection of the second wall portion  42 . The depth at which the recessed shape La is formed in the Z-axis direction is not particularly limited, but preferably has a length three times or more larger than an inner diameter D 1  of the ejection port  35  in order to make the ejection rate of the drug solution L 1  high. 
     Subsequently, the actuator  22  is driven so as to move the abutment portion  23  downward and deflect the first wall portion  41  downward. Then, a positive pressure is generated in the liquid chamber  43 , and therefore, the second wall portion  42  is also deflected downward. By the downward deflection of the second wall portion  42 , a positive pressure is generated in the pressure chamber  34 , and the columnar shape Lb is formed along the Z-axis direction at a central portion of the recessed shape La formed at the surface of the drug solution L 1  at the ejection port  35 . Then, the columnar shape Lb grows downward, and when it has grown to a desired length, the columnar shape Lb is cut off from the surface of the drug solution L 1 , and the drug solution L 1  is ejected in a state where the columnar shape Lb is maintained. The sixth state from the left to the rightmost state in  FIG. 5  show a manner in which the columnar shape Lb is formed at the surface of the drug solution L 1  at the ejection port  35 , and the drug solution L 1  in the columnar shape Lb is ejected by the downward deflection of the second wall portion  42 . 
     When viewed from the Z-axis direction, an inner diameter D 2  of the recessed shape La with respect to the inner diameter D 1  of the ejection port  35  is about ⅔ times, and a diameter D 3  of the columnar shape Lb with respect to the inner diameter D 2  is about ⅓ times. The drug solution administration unit  1  of this embodiment can eject the drug solution L 1  from the ejection port  35  so that the diameter D 3  is 20 μm or more and 200 μm or less and the ejection rate of the drug solution L 1  when it is ejected from the ejection port  35  is 30 m/s or more. The inkjet device configured to include the actuator  22  and the displacement magnification mechanism  40  as described with reference to  FIGS. 1 to 4  can eject the drug solution L 1  at a high rate such that the ejection rate is 30 m/s or more. 
     As summarized here, the drug solution administration unit  1  of this embodiment is an inkjet device including the actuator unit  2  and the body unit  3  as the inkjet head that ejects the drug solution L 1 , and the controller  10  that controls the ejection of the drug solution L 1  from the inkjet head. Then, a drug solution administration method in which the drug solution L 1  is made to pierce a target site and is administered to the target site can be implemented by ejecting the drug solution L 1  from the ejection port  35  so that the diameter D 3  of the drug solution L 1  when it is ejected from the ejection port  35  is 20 μm or more and 200 μm or less and the ejection rate of the drug solution L 1  when it is ejected from the ejection port  35  is 30 m/s or more using the drug solution administration unit  1 . 
     In this manner, by administering the drug solution L 1  to the target site under the conditions that the drug solution L 1  is ejected so that the diameter D 3  is 20 μm or more and 200 μm or less and the ejection rate is 30 m/s or more, the drug solution L 1  can be administered while piercing the surface of the target site without causing a patient to feel pain, and the drug solution L 1  can be made to sufficiently penetrate into the target site. Further, by ejecting the drug solution L 1  from the inkjet head, the drug solution L 1  can be administered to the target site without bringing the other constituent members such as a needle into contact with the target site, and thus, the adverse effect can also be suppressed. Note that the “target site” represents an affected area or the like to which the drug solution is desired to be administered such as a skin of a human body tissue or an organ such as an eye, a heart, a lung, a liver, or a stomach, or a skin, an organ, or the like of an animal other than a human. Further, the “diameter” as used herein is a diameter when viewed from a direction along the Z-axis direction as described above, in other words, the ejection direction of the drug solution L 1 . 
     Here, the actuator unit  2  and the body unit  3  as the inkjet head have the ejection port  35  that ejects the drug solution L 1 , the pressure chamber  34  that communicates with the ejection port  35 , the actuator  22  that is displaced in a pressing direction corresponding to the downward direction in  FIGS. 1 to 4  and in an opposite direction to the pressing direction corresponding to the upward direction in  FIG. 4 , and the displacement magnification mechanism  40  that magnifies the amount of displacement and transmits the displacement of the actuator  22  to the pressure chamber  34 . It is difficult to eject the drug solution L 1  so that the ejection rate is 30 m/s or more using a general inkjet head. However, the drug solution administration unit  1  of this embodiment can press the pressure chamber  34  with a larger amount of displacement than the amount of displacement of the actuator  22  due to the displacement magnification mechanism  40  as described above, and therefore, the drug solution L 1  can be ejected so that the ejection rate is 30 m/s or more. 
     Further, the displacement magnification mechanism  40  includes the liquid chamber  43  in which the liquid L 2  is enclosed. In addition, the displacement magnification mechanism  40  includes the first wall portion  41  that constitutes a part of a wall face of the liquid chamber  43 , and that is displaced according to the displacement of the actuator  22  so as to apply a pressure to the liquid L 2 . Further, the displacement magnification mechanism  40  includes the second wall portion  42  that constitutes a part of a wall face of the liquid chamber  43 , that has a smaller area facing the liquid L 2  than the area of the first wall portion  41  facing the liquid L 2 , and that is displaced in the pressing direction in a state where an elastic force acting in the opposite direction to the pressing direction is generated by a pressure of the liquid L 2  when a pressure is applied to the liquid L 2  by the displacement of the first wall portion  41 . That is, by adopting a configuration in which the displacement magnification mechanism  40  is provided with the liquid chamber  43  having the first wall portion  41  and the second wall portion  42 , the high-precision displacement magnification mechanism can be constituted. Then, by the high-precision displacement magnification mechanism  40 , the drug solution L 1  can be ejected so that the ejection rate is 30 m/s or more with high precision. 
     Further, as described above, under the control of the controller  10 , the surface of the drug solution L 1  formed at the ejection port  35  is drawn toward the inside of the pressure chamber  34  so as to form the recessed shape La by displacing the actuator  22  in the opposite direction to the pressing direction. Then, by displacing the actuator  22  in the pressing direction thereafter, the columnar shape Lb protruding toward the outside of the pressure chamber  34  is formed at a central portion when viewed from the ejection direction of the drug solution L 1  at the surface in the recessed shape La and also the drug solution L 1  in the columnar shape Lb can be ejected. In this manner, by displacing the actuator  22  so as to once recess the surface of the drug solution L 1  formed at the ejection port  35 , and thereafter form the columnar shape Lb at the central portion of the recessed portion, the drug solution L 1  can be ejected so that the ejection rate is 30 m/s or more with high precision. Further, when the drug solution L 1  is ejected in a spherical shape, it is difficult to visually confirm whether or not the drug solution L 1  is ejected, however, by ejecting the drug solution L 1  in the columnar shape Lb, it is possible to visually confirm whether or not the drug solution L 1  is ejected. 
     However, the ejection method is not limited to the ejection method as described above. The actuator  22  may be displaced in the pressing direction from the beginning without displacing the actuator  22  in the opposite direction to the pressing direction under the control of the controller  10 . According to the configuration in which the displacement magnification mechanism  40  is included, even if such an ejection method is adopted, the drug solution L 1  can be ejected so that the ejection rate is 30 m/s or more. 
     The drug solution administration unit  1  of this embodiment includes a stroboscope having the light  14  or the like as the ejection rate measurement unit for the drug solution L 1 . Then, a user can perform administration of the drug solution L 1  after measuring the ejection rate of the drug solution L 1 . The dose is sometimes restricted according to the type of the drug solution L 1  to be used, however, by implementing the drug solution administration method using the drug solution administration unit  1  of this embodiment, the drug solution L 1  can be administered after adjusting the conditions so that the drug solution L 1  can pierce the target site. 
     The inkjet head of the drug solution administration unit  1  of this embodiment can change the number of times of ejection of the drug solution L 1  at the same position of the target site from one time to a plurality of times by, for example, continuously performing an ejection operation under the control of the controller  10 . By changing the number of times of ejection of the drug solution L 1 , the drug solution L 1  can be administered while adjusting the penetration depth of the drug solution L 1  into the target site. A preferred penetration depth of the drug solution L 1  into the target site varies depending on the state of the target site, the type of the drug solution L 1  to be used, or the like. If the number of times of ejection of the drug solution L 1  at the same position of the target site is increased by continuously performing the ejection operation a plurality of times, the penetration depth of the drug solution L 1  into the target site is increased. By using the drug solution administration unit  1  of this embodiment, the drug solution L 1  can be administered while adjusting the penetration depth of the drug solution L 1  into the target site by a simple method in which the number of times of ejection of the drug solution L 1  at the same position of the target site is changed. 
     The inkjet head of the drug solution administration unit  1  of this embodiment is configured to be able to eject the drug solution L 1  with a plurality of ejection diameters under the control of the controller  10 . Specifically, it is configured to be able to eject the drug solution L 1  with a plurality of ejection diameters by adjusting the amount of displacement in a direction along the Z-axis direction of the actuator  22  or by continuously displacing the actuator  22  at a high rate. By changing the ejection diameter of the drug solution L 1  under the control of the controller  10 , the drug solution L 1  can be administered while adjusting the application range of the drug solution L 1  to the local target site. By narrowing the ejection diameter of the drug solution L 1 , the application range of the drug solution L 1  to the local target site can be adjusted to an extremely small range. By using the drug solution administration unit  1  of this embodiment, the drug solution L 1  can be administered while adjusting the application range of the drug solution L 1  to the local target site by changing the ejection diameter of the drug solution L 1 . Note that the ejection diameter of the drug solution L 1  corresponds to the above-mentioned diameter D 3 . 
     The inkjet head of the drug solution administration unit  1  of this embodiment is configured to be able to eject the drug solution L 1  at a plurality of ejection rates under the control of the controller  10 . Specifically, it is configured to be able to eject the drug solution L 1  at a plurality of ejection rates by adjusting the amount of displacement in a direction along the Z-axis direction of the actuator  22  or the rate of displacement of the actuator  22 . The drug solution L 1  can be administered while adjusting the penetration depth of the drug solution L 1  into the target site by changing the ejection rate of the drug solution L 1  under the control of the controller  10 . By increasing the ejection rate of the drug solution L 1 , the penetration depth of the drug solution L 1  into the target site is increased. By using the drug solution administration unit  1  of this embodiment and changing the ejection rate of the drug solution L 1 , the drug solution L 1  can be administered while adjusting the penetration depth of the drug solution L 1  into the target site. 
     The drug solution administration unit  1  of this embodiment is a handy type, and a desired amount of the drug solution L 1  can be administered to the target site by a user holding it with a hand. However, it is also possible to administer the drug solution L 1  to the target site by mounting the drug solution administration unit  1  of this embodiment on a moving mechanism for moving the drug solution administration unit  1  to a desired position. In other words, the inkjet device includes a moving mechanism for changing the position of the drug solution administration unit  1 , and in the administration of the drug solution L 1 , the drug solution L 1  can also be administered while changing the position of the inkjet head that is the ejection portion of the drug solution administration unit  1  by the moving mechanism. Therefore, when the target site is located over a wide area, or the like, the drug solution L 1  can be easily administered at a preferred position. Further, for example, when the drug solution L 1  is administered to a site from the elbow to the wrist, or the like, the drug solution L 1  shall be administered to a region where the hardness of the skin that is the target site varies, however, the drug solution L 1  can be administered over a wide area while changing the number of times of ejection, the ejection rate, or the like according to the hardness of the skin. Note that the inkjet device preferably includes an indentometer capable of measuring the hardness of the skin. 
     Here, the moving mechanism may be configured to also move a constituent member other than the inkjet head together therewith as long as it is configured to be able to move at least the inkjet head that is the ejection portion of the drug solution administration unit  1 . Further, the moving mechanism may be configured to one-dimensionally move (reciprocally move) the inkjet head continuously or intermittently, and other than this, it may also be configured to two-dimensionally or three-dimensionally move the inkjet head continuously or intermittently. 
     Second Embodiment 
     Next, a drug solution administration unit  1  of a second embodiment will be described with referent to  FIG. 6 .  FIG. 6  is a view corresponding to  FIG. 2  for the drug solution administration unit  1  of the first embodiment, and also in  FIG. 6 , the constituent members common to those in the first embodiment are denoted by the same reference numerals, and a detailed description thereof will be omitted. Here, the drug solution administration unit  1  of this embodiment has the same characteristics as those of the drug solution administration unit  1  of the first embodiment described above, and also has the same form as that of the drug solution administration unit  1  of the first embodiment except for the parts described below. 
     As shown in  FIG. 6 , the drug solution administration unit  1  of this embodiment includes a body unit  3  and a control unit  5  having a controller  10  and a power supply (not shown) or the like. The actuator  22  is provided in the body unit  3 . The control unit  5  can be moved in the arrow direction in  FIG. 6  with respect to the body unit  3 , and is configured to be attachable to and detachable from the body unit  3 . 
     As shown by the drug solution administration units  1  of the first embodiment and the second embodiment, part of the constituent members can be configured to be attachable to and detachable from the body unit  3 . The actuator unit  2  may be configured to be attachable to and detachable from the body unit  3  or the control unit  5  may be configured to be attachable to and detachable from the body unit  3 , and other than these, a drug solution tank that stores the drug solution L 1  may be configured to be attachable and detachable, a power supply unit may be configured to be attachable and detachable, and so on. By adopting a configuration in which part of the constituent members are attachable to and detachable from the body unit  3  in this manner, a specification can be made capable of easily replacing part of the constituent members. Then, for example, by storing management information such as the date of expiry in the attachable and detachable constituent members, for example, an old drug solution L 1  is prevented from being used, and so on, and thus, the drug solution administration unit  1  can be managed with high precision. 
     Third Embodiment 
     Next, a drug solution administration unit  1  of a third embodiment will be described with referent to  FIG. 7 .  FIG. 7  is a view corresponding to  FIG. 1  for the drug solution administration unit  1  of the first embodiment, and also in  FIG. 7 , the constituent members common to those in the first embodiment and the second embodiment are denoted by the same reference numerals, and a detailed description thereof will be omitted. Here, the drug solution administration unit  1  of this embodiment has the same characteristics as those of the drug solution administration unit  1  of the first embodiment described above, and also has the same form as that of the drug solution administration unit  1  of the first embodiment except for the parts described below. 
     As shown in  FIG. 7 , the drug solution administration unit  1  of this embodiment is provided with a spacer  15  in a cylindrical shape surrounding the circumference of the ejection port  35 . The drug solution administration unit  1  of this embodiment has exactly the same configuration as the drug solution administration unit  1  of the first embodiment except that the spacer  15  is provided. The spacer  15  of this embodiment is configured to be stretchable in the ejection direction along the Z-axis direction, and is configured to be able to adjust the length in the ejection direction from the ejection port  35  within a range of 5 mm or more and 20 mm or less. 
     That is, the drug solution administration unit  1  of this embodiment includes the spacer  15  as an ejection distance specifying unit that specifies the ejection distance of the drug solution L 1 , which is a distance from the ejection port  35  to the target site, and by specifying the ejection distance with the spacer  15 , the administration of the drug solution L 1  is made possible within a range where the ejection distance is 5 mm or more and 20 mm or less. If the ejection distance is too short, the drug solution L 1  may bounce back to the inkjet head of the drug solution administration unit  1  to contaminate the drug solution administration unit  1  and make it unhygienic, and if the ejection distance is too long, it may become difficult for the drug solution L 1  to reach the target site at a desired ejection rate. By administering the drug solution L 1  using the drug solution administration unit  1  of this embodiment, the administration of the drug solution L 1  can be performed within a range where the ejection distance is 5 mm or more and 20 mm or less. Therefore, the inkjet head can be prevented from being contaminated and becoming unhygienic, or the drug solution L 1  can be prevented from not reaching the target site at a desired ejection rate. 
     The present disclosure is not limited to the above-mentioned embodiments, but can be realized in various configurations without departing from the gist of the present disclosure. The technical features in the embodiments corresponding to the technical features in the respective forms described in “SUMMARY” of the present disclosure may be appropriately replaced or combined in order to solve part or all of the problems described above or achieve part or all of the advantageous effects described above. Further, the technical features may be appropriately deleted unless they are described as essential features in the specification.