Abstract:
There is provided a micropump, including: a substrate; a pressure chamber formed in the substrate; and a connecting flow channel connected to the pressure chamber and extended in a vertical direction with respect to a radial direction of the pressure chamber.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of Korean Patent Application No. 10-2014-0005457 filed on Jan. 16, 2014, with the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. 
       BACKGROUND 
       [0002]    The present disclosure relates to a micropump allowing for a micro flow rate. 
         [0003]    In order to develop new medicines and experimentally determine the stability of new medicines, it is necessary to observe reactions between new medicines (that is, drugs) and cells. Generally, experiments involving reactions between drugs and the cells are performed using a culture dish, or the like. 
         [0004]    However, since reactions between drugs and cells made in the culture dish may be very different from reactions between drugs and cells occurring within the human body, it may be difficult to accurately observe or inspect reactions between drugs and cells through only a result of experiments using a culture dish. Therefore, there is a need to develop a new device capable of observing reactions between drugs and cells in an environment similar to that inside a human body. 
         [0005]    To this end, the inventor has developed technology allowing for the circulation of a culture medium. In order to smoothly culture the cell, however, since a small amount of culture medium needs to be constantly supplied, the development of a micropump capable of constantly supplying a small amount of fluid has been demanded. 
       SUMMARY 
       [0006]    Some embodiments of the present invention may provide a micropump capable of constantly supplying a small amount of fluid. 
         [0007]    According to some embodiments of the present disclosure, a micropump may include: a substrate; a pressure chamber formed in the substrate; and a connecting flow channel connected to the pressure chamber and extended in a vertical direction with respect to a radial direction of the pressure chamber. 
         [0008]    The pressure chamber may have a circular shape, an oval shape, or a shape formed by curves having one or more radii of curvature. 
         [0009]    The connecting flow channel may include one or more expansion parts. 
         [0010]    The connecting flow channel may be connected to the pressure chamber in the expansion parts. 
         [0011]    The micropump may further include an upper substrate disposed on the substrate and having an inlet and an outlet connected to the connecting flow channel. 
         [0012]    The micropump may further include a piezoelectric actuator disposed on the substrate. 
         [0013]    According to some embodiments of the present disclosure, a micropump may include: a substrate; a pressure chamber formed in the substrate; and a connecting flow channel connected to the pressure chamber and having a curved shape. 
         [0014]    The pressure chamber may have a circular shape, an oval shape, or a shape formed by curves having one or more radii of curvature. 
         [0015]    The connecting flow channel may be formed by a curve circumscribed with the pressure chamber. 
         [0016]    The connecting flow channel may be formed by a curve inscribed in the pressure chamber. 
         [0017]    The connecting flow channel may include one or more expansion parts. 
         [0018]    The connecting flow channel may be connected to the pressure chamber in the expansion parts. 
         [0019]    The micropump may further include an upper substrate disposed on the substrate and having an inlet and an outlet connected to the connecting flow channel. 
         [0020]    The micropump may further include a piezoelectric actuator disposed on the substrate. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    The above and other aspects, features and other advantages of the present disclosure will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
           [0022]      FIG. 1  is an exploded perspective view of a micropump according to an exemplary embodiment of the present disclosure; 
           [0023]      FIG. 2  is a bottom view of a substrate of  FIG. 1 ; 
           [0024]      FIG. 3  is an assembled perspective view of the micropump of  FIG. 1 ; 
           [0025]      FIG. 4  is a cross-sectional view of the micropump of  FIG. 3 ; 
           [0026]      FIG. 5  is an enlarged view of portion A of  FIG. 4 ; 
           [0027]      FIG. 6  is a plan view of a valve of  FIG. 5 ; 
           [0028]      FIG. 7  is an enlarged view of portion B of  FIG. 4 ; 
           [0029]      FIG. 8  is a plan view of a valve of  FIG. 7 ; 
           [0030]      FIG. 9  is an exploded perspective view of a micropump according to another exemplary embodiment of the present disclosure; 
           [0031]      FIG. 10  is a bottom view of a substrate of  FIG. 9 ; and 
           [0032]      FIG. 11  is a bottom view of another example of the substrate of  FIG. 9 . 
       
    
    
     DETAILED DESCRIPTION 
       [0033]    Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. 
         [0034]    The disclosure may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. 
         [0035]    In the drawings, the shapes and dimensions of elements maybe exaggerated for clarity, and the same reference numerals will be used throughout to designate the same or like elements. 
         [0036]      FIG. 1  is an exploded perspective view of a micropump according to an exemplary embodiment of the present disclosure,  FIG. 2  is a bottom view of a substrate of  FIG. 1 ,  FIG. 3  is an assembled perspective view of the micropump of  FIG. 1 ,  FIG. 4  is a cross-sectional view of the micropump of  FIG. 3 ,  FIG. 5  is an enlarged view of portion A of  FIG. 4 ,  FIG. 6  is a plan view of a valve of  FIG. 5 ,  FIG. 7  is an enlarged view of portion B of  FIG. 4 ,  FIG. 8  is a plan view of a valve of  FIG. 7 ,  FIG. 9  is an exploded perspective view of a micropump according to another exemplary embodiment of the present disclosure,  FIG. 10  is a bottom view of a substrate of  FIG. 9 , and  FIG. 11  is a bottom view of another example of the substrate of  FIG. 9 . 
         [0037]    A micropump  100  according to an exemplary embodiment of the present disclosure will be described with reference to  FIGS. 1 through 3 . 
         [0038]    The micropump  100  according to an exemplary embodiment of the present disclosure may include a bottom substrate  110 , a flow channel forming substrate  120 , and a valve substrate  140 . In addition, the micropump  100  may further include an actuator  150 , if necessary. Here, the bottom substrate  110 , the flow channel forming substrate  120 , and the valve substrate  140  may be sequentially stacked. 
         [0039]    The bottom substrate  110  may form a base part of the micropump  100 . The bottom substrate  110  may be formed of a single crystal silicon substrate or a silicon on insulator (SOI) substrate. In this case, the bottom substrate  110  may be a stacked structure in which a silicon substrate and a plurality of insulating members are stacked. 
         [0040]    The flow channel forming substrate  120  may be a substrate in which a flow channel through which a fluid (e.g., a culture medium or drugs) is conveyed is formed. To this end, a first surface (an upper surface based on  FIG. 1 ) of the flow channel forming substrate  120  may be provided with a first connecting opening  132  and a second connecting opening  134 , and a second surface (a lower surface based on  FIG. 1 ) of the flow channel forming substrate  120  may be provided with a pressure chamber  122  and a connecting flow channel  124 . 
         [0041]    The pressure chamber  122  may have a volume capable of receiving a predetermined amount of fluid. For example, the pressure chamber  122  may have volume capable of generating a first magnitude of pressure. Further, the pressure chamber  122  may be designed to have a changeable volume, if necessary. For example, the volume of the pressure chamber  122  may be expanded or reduced by the piezoelectric actuator  150 . To this end, the piezoelectric actuator  150  may be formed on one surface of the pressure chamber  122 . The pressure chamber  122  may have a circular shape as shown in  FIG. 2 . However, the cross-sectional shape of the pressure chamber  122  is not limited to the circular shape. For example, the cross-sectional shape of the pressure chamber  122  may include an oval shape, a regular shape, or an irregular shape. 
         [0042]    The connecting flow channel  124  may connect the first connecting opening  132  and the second connecting opening  134  to each other. For example, the connecting flow channel  124  may have a linear form connecting the first connecting opening  132  and the second connecting opening  134  to each other. As an example, the connecting flow channel  124  may have the linear form extended in a tangential direction for the circular pressure chamber  122 . That is, a vertical line V extended from the center of the pressure chamber  122  to a straight line N may be substantially equal to a radius R of the pressure chamber  122 . 
         [0043]    The connecting flow channel  124  may have one or more expansion parts. For example, the connecting flow channel  124  may be provided with two expansion parts  126  and  128 . Here, a first expansion part  126  may be formed in a section connecting the first connecting opening  132  and the pressure chamber  122  to each other, and a second expansion part  128  may be formed in a section connecting the pressure chamber  122  and the second connecting opening  134  to each other. However, the number and the position of expansion parts  126  and  128  are not limited to the above-described configuration. For example, the number of expansion parts may be increased or decreased, and the position thereof may also be changed. 
         [0044]    The first expansion part  126  may have a cross-sectional area gradually increased from the first connecting opening  132  toward the pressure chamber  122 . For example, the first expansion part  126  may have a triangular shape in which it is widened in a direction from the first connecting opening  132  toward the pressure chamber  122 . 
         [0045]    The second expansion part  128  may have a cross-sectional area gradually increased from the pressure chamber  122  toward the second connecting opening  134 . For example, the second expansion part  128  may have a triangular shape in which it is widened from the pressure chamber  122  toward the second connecting opening  134 . 
         [0046]    The above-described shape of the connecting flow channel  124  may significantly reduce or prevent a phenomenon in which the fluid flows backwards from the second connecting opening  134  to the first connecting opening  132 . For reference, the connecting flow channel  124  maybe changed to have another shape as long as it may significantly reduce or prevent the back flow of the fluid. 
         [0047]    Similar to the bottom substrate  110 , the flow channel forming substrate  120  may be formed of a single crystal silicon substrate or a silicon on insulator (SOI) substrate. The flow channel forming substrate  120  maybe integrally formed with the bottom substrate  110  through a sintering process. 
         [0048]    The valve substrate  140  may be formed on one surface of the flow channel forming substrate  120  and may control a movement of the fluid flowing in the flow channel forming substrate  120 . To this end, the valve substrate  140  may include one or more valves  210  and  220 . 
         [0049]    The valve substrate  140  may be provided with a first opening  142  and a second opening  144 . Here, the first opening  142  maybe connected to the first connecting opening  132  of the flow channel forming substrate  120 , and the second opening  144  may be connected to the second connecting opening  134  of the flow channel forming substrate  120 . 
         [0050]    The valves  210  and  220  may be installed in the first opening  142  and the second opening  144 , respectively. More specifically, the first valve  210  maybe installed in the first opening  142  and the second valve  220  may be installed in the second opening  144 . Meanwhile, although the valves in the present embodiment are installed in both of the first opening  142  and the second opening  144  by way of example, a single valve may only be installed in a corresponding opening, if necessary. 
         [0051]    The valve substrate  140  may be formed of plastic or a synthetic resin material. In this case, the valve substrate  140  and the valves  210  and  220  may be easily processed, resulting in a reduction of production costs. However, if necessary, the valve substrate  140  may be formed of a silicon substrate, and only the valves  210  and  220  may be formed of plastic or a synthetic resin material. 
         [0052]    The piezoelectric actuator  150  may be formed on the flow channel forming substrate  120 . More specifically, the piezoelectric actuator  150  may be formed on one surface (the upper surface based on  FIG. 1 ) of the flow channel forming substrate  120 . The piezoelectric actuator  150  may include a lower electrode, a piezoelectric element, and an upper electrode. More specifically, the lower electrode may be formed on the upper surface of the flow channel forming substrate  120 , and the piezoelectric element may be formed on an upper surface of the lower electrode, and the upper electrode may be formed on an upper surface of the piezoelectric element. The piezoelectric actuator  150  may generate driving force by deforming the piezoelectric element through a current signal supplied through the upper electrode and the lower electrode. Here, the driving force of the piezoelectric actuator  150  may be transferred to the pressure chamber  122  of the flow channel forming substrate  120  to thereby cause a fluid flow. 
         [0053]    The micropump  100  may allow a fluid to be moved only in one direction through the valves  210  and  220 , and details thereof will be provided with reference to  FIGS. 4 through 8 . 
         [0054]    An inlet side (a portion indicated by B in  FIG. 4 ) of the micropump  100  may be configured as shown in  FIG. 5 . For example, the first connecting opening  132  of the flow channel forming substrate  120  may have a first diameter D1. Further, the first opening  142  of the valve substrate  140  may have a second diameter D2. Here, the first diameter D1 may be larger than the second diameter D2. Further, a first space  146  capable of receiving the first valve  210  may be formed below the lower surface of the valve substrate  140 . 
         [0055]    The first valve  210  maybe installed in the first space  146 . The first valve  210  may be vertically moved in a height direction (based on  FIG. 5 ) of the first space  146  and may close the first opening  142 . To this end, the first valve  210  may be provided with a plurality of discharging openings  212  as shown in  FIG. 6 . Here, a diameter D6 of a circle which is inscribed in the plurality of discharging openings  212  may be larger than the second diameter D2 of the first opening  142 . Further, a diameter D5 of a circle which is circumscribed with the plurality of discharging openings  212  may be larger than the second diameter D2 of the first opening  142 , but may be smaller than the first diameter D1 of the first connecting opening  132 . 
         [0056]    The fluid may be introduced into the micropump  100  through the following method: 
         [0057]    When the fluid is moved from the first opening  142  to the first connecting opening  132 , the discharging openings  212  are open as the first valve  210  is moved downwardly, thereby allowing the fluid to be moved. On the other hand, when the fluid is moved from the first connecting opening  132  to the first opening  142 , the first opening  142  is closed as the first valve  210  is moved upwardly, thereby blocking the fluid from being moved. 
         [0058]    An outlet side (a portion indicated by C in  FIG. 4 ) of the micropump  100  may be configured as shown in  FIG. 7 . For example, the second connecting opening  134  of the flow channel forming substrate  120  may have a third diameter D3. Further, the second opening  144  of the valve substrate  140  may have a fourth diameter D4. Here, the third diameter D3 maybe smaller than the fourth diameter D4. Further, a second space  148  capable of receiving the second valve  220  may be formed below the lower surface of the valve substrate  140 . 
         [0059]    The second valve  220  maybe installed in the second space  148 . The second valve  220  may be vertically moved in a height direction (based on  FIG. 7 ) of the second space  148  and may close the second opening  134 . To this end, the second valve  220  may be provided with a plurality of discharging openings  222  as shown in  FIG. 8 . Here, a diameter D8 of a circle which is inscribed in the plurality of discharging openings  222  may be larger than the third diameter D3 of the second connecting opening  134 , and a diameter D7 of a circle which is circumscribed with the plurality of discharging openings  222  may be smaller than the fourth diameter D4 of the second opening  144 . 
         [0060]    The fluid may be discharged from the micropump  100  through the following method: 
         [0061]    When the fluid is moved from the second connecting opening  134  to the second opening  144 , the discharging openings  222  are open as the second valve  220  is moved upwardly, thereby allowing the fluid to be moved. On the other hand, when the fluid is moved from the second opening  144  to the second connecting opening  134 , the discharging openings  222  are closed as the second valve  220  is moved downwardly, thereby blocking the fluid from being moved. 
         [0062]    In the above-described configuration of the micropump  100 , the flow of the fluid from the first connecting opening  132  to the second connecting opening  134  is not interrupted by the pressure chamber  122 , the fluid may be smoothly moved. Further, since internal pressure may be easily decreased in the pressure chamber  122  by the fluid flowing through the connecting flow channel  124 , the micropump  100  may easily perform a purging process in the pressure chamber  122 . 
         [0063]    Further, the micropump  100  may effectively block the back flow of the fluid by the above-described valve configuration. Further, since the micropump  100  controls the direction of movement of the fluid by the valves  210  and  220 , it may constantly move a small amount of fluid. Further, the valve substrate  140  provided with the valves  210  and  220  may be separately manufactured, whereby a process of manufacturing the micropump  100  may be simplified and production costs of the micropump  100  may be reduced. 
         [0064]    Next, the micropump  100  according to another exemplary embodiment of the present disclosure will be described with reference to  FIGS. 9 through 11 . For reference, in the following exemplary embodiment, the same element as those in the above-described exemplary embodiment will be denoted by the same reference numerals and a detailed description thereof will be omitted. 
         [0065]    The micropump  100  according to this exemplary embodiment of the present disclosure may be different from that according to the above-described exemplary embodiment in terms of positions of the pressure chamber  122  and the connecting flow channel  124 . For example, according to this exemplary embodiment of the present disclosure, the pressure chamber  122  and the connecting flow channel  124  may be formed in an upper surface of the flow channel forming substrate  120  as shown in  FIG. 9 . 
         [0066]    In this case, the bottom substrate  110  may be removed from the micropump  100 , whereby the process of manufacturing the micropump  100  may be simplified and production costs thereof may be reduced. 
         [0067]    Further, the micropump  100  according to this exemplary embodiment of the present disclosure may be different from that according to the above-described exemplary embodiment in terms of the shape of the connecting flow channel  124 . For example, in the micropump  100  according to this exemplary embodiment of the present disclosure, as shown in  FIGS. 10 and 11 , the connecting flow channel  124  may be formed in shapes of curves R1 and R2 which are substantially circumscribed with or inscribed in the circular pressure chamber  122 . 
         [0068]    The micropump  100  having the above-mentioned configuration may extend a length of the connecting flow channel  124  without changing change the size of the substrate. Particularly, since the pressure chamber  122  and the connecting flow channel  124  may be concentrated in a limited region, whereby the miniaturization of the micropump  100  may be facilitated. 
         [0069]    While exemplary embodiments have been shown and described above, it will be apparent to those skilled in the art that modifications and variations could be made without departing from the spirit and scope of the present disclosure as defined by the appended claims.