Abstract:
There is provided a micro-pump including: a bottom substrate; a flow path forming substrate coupled to the bottom substrate and including an inlet having a fluid introduced therein and an outlet having the fluid ejected therefrom; and a valve substrate coupled to the flow path forming substrate and including at least one valve controlling the fluid to be introduced and ejected.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the priority of Korean Patent Application No. 10-2012-0127216 filed on Nov. 12, 2012, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a micro-pump, and more particularly, to a micro-pump capable of uniformly supplying a small amount of fluid. 
         [0004]    2. Description of the Related Art 
         [0005]    Observation of a reaction between new drugs and a cell is required for developing new drugs and testing the stability thereof. In general, a reaction test between a drug and a cell is performed by using a culture dish, or the like. 
         [0006]    However, since a reaction between a drug and a cell, occurring in the culture dish, is significantly different from a reaction between the drug and the cell, occurring inside a body, it may be difficult to accurately observe or examine a reaction between a drug and a cell only through a result of the test using the culture dish. Therefore, development of a new device that can observe the reaction between the drug and the cell in a similar environment to that of a body is required. 
         [0007]    To this end, the applicant has developed a technology of circulating a culture medium. However, since a small amount of culture medium needs to be constantly supplied, for smoothly culturing the cell, the development of a micro-pump for uniformly supplying a small amount of fluid is needed. 
         [0008]    Meanwhile, there are Patent Documents 1 and 2 as prior art inventions relating to micro-pumps. According to Patent Documents 1 and 2, a small amount of fluid may be moved by using driving force of a piezoelectric element. However, Patent Document 1 does not include a valve that completely blocks a fluid flow, which makes it difficult to transfer a quantitative amount of fluid. Unlike this, Patent Document 2 includes valves 5 and 6 provided in valve substrates 3 and 4, respectively, which makes it possible to transfer the quantitative amount of fluid; however, it is disadvantageously difficult to manufacture the valve substrates 3 and 4. 
       Related Art Document 
       [0000]    
       
         (Patent Document 1) KR No. 2008-070358 A 
         (Patent Document 2) JP No. 2000-249074 A 
       
     
       SUMMARY OF THE INVENTION 
       [0011]    An aspect of the present invention provides a micro-pump capable of uniformly supplying a small amount of fluid. 
         [0012]    According to an aspect of the present invention, there is provided a micro-pump including: a bottom substrate; a flow path forming substrate coupled to the bottom substrate and including an inlet having a fluid introduced therein and an outlet having the fluid ejected therefrom; and a valve substrate coupled to the flow path forming substrate and including at least one valve controlling the fluid to be introduced and ejected. 
         [0013]    The inlet and outlet may be formed in a first surface of the flow path forming substrate, and a pressure chamber connecting the inlet and the outlet to each other may be formed in a second surface of the flow path forming substrate. 
         [0014]    The micro-pump may further include: an actuator formed on the first surface of the flow path forming substrate and applying pressure to the pressure chamber. 
         [0015]    The bottom substrate and the flow path forming substrate maybe respectively formed of a single crystal silicon substrate or silicon on insulator (SOI) substrate. 
         [0016]    The valve substrate may be formed of a plastic or synthetic resin material. 
         [0017]    A first hole connected to the inlet and a second hole connected to the outlet may be formed in the valve substrate, and the valve may be installed in at least one of the first hole and the second hole. 
         [0018]    The valve may include: a thin film member; a first opening and closing member formed by a first cutting line to cut one part of the thin film member; and a second opening and closing member formed by a second cutting line to cut the other part of the thin film member. 
         [0019]    The first cutting line may have a length greater than that of the second cutting line. 
         [0020]    The first cutting line may be curved to have a first radius, and the second cutting line maybe curved to have a second radius. 
         [0021]    The first radius and the second radius may have different sizes. 
         [0022]    According to another aspect of the present invention, there is provided a micro-pump including: a bottom substrate; a flow path forming substrate coupled to the bottom substrate and including an inlet having a fluid introduced therein and an outlet having the fluid ejected therefrom; a vibration substrate coupled to the flow path forming substrate; and a valve substrate coupled to the vibration substrate and including at least one valve controlling the fluid to be introduced and ejected. 
         [0023]    The inlet, the outlet, and a pressure chamber connecting the inlet and the outlet to each other maybe formed in the flow path forming substrate, and through holes respectively connected to the inlet and the outlet may be formed in the vibration substrate. 
         [0024]    The micro-pump may further include: an actuator formed on a first surface of the vibration substrate and applying pressure to the pressure chamber. 
         [0025]    The bottom substrate, the flow path forming substrate, and the vibration substrate may be respectively formed of a single crystal silicon substrate or silicon on insulator (SOI) substrate. 
         [0026]    The valve substrate may be formed of a plastic or synthetic resin material. 
         [0027]    A first hole connected to the inlet and a second hole connected to the outlet may be formed in the valve substrate, and the valve may be installed in at least one of the first hole and the second hole. 
         [0028]    The valve may include: a thin film member; a first opening and closing member formed by a first cutting line to cut one part of the thin film member; and a second opening and closing member formed by a second cutting line to cut the other part of the thin film member. 
         [0029]    The first cutting line may have a length greater than that of the second cutting line. 
         [0030]    The first cutting line may be curved to have a first radius, and the second cutting line maybe curved to have a second radius. 
         [0031]    The first radius and the second radius may have different sizes. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0032]    The above and other aspects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
           [0033]      FIG. 1  is a cross-sectional view of a micro-pump according to an embodiment of the present invention; 
           [0034]      FIG. 2  is an expanded view of portion A of  FIG. 1 ; 
           [0035]      FIG. 3  is a plan view of a valve of  FIG. 2 ; 
           [0036]      FIG. 4  is an expanded view of portion B of  FIG. 1 ; 
           [0037]      FIG. 5  is a plan view of a valve of  FIG. 4 ; 
           [0038]      FIGS. 6 through 13  are views of modifications of a valve; and 
           [0039]      FIG. 14  is a cross-sectional view of a micro-pump according to another embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0040]    Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The invention 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 invention to those skilled in the art. In the drawings, the shapes and dimensions of elements may be exaggerated for clarity, and the same reference numerals will be used throughout to designate the same or like elements. 
         [0041]      FIG. 1  is a cross-sectional view of a micro-pump according to an embodiment of the present invention.  FIG. 2  is an expanded view of portion A of  FIG. 1 .  FIG. 3  is a plan view of a valve of  FIG. 2 .  FIG. 4  is an expanded view of portion B of  FIG. 1 .  FIG. 5  is a plan view of a valve of  FIG. 4 .  FIGS. 6 through 13  are views of modifications of a valve.  FIG. 14  is a cross-sectional view of a micro-pump according to another embodiment of the present invention. 
         [0042]    A micro-pump  100  according to an embodiment of the present invention will now be described with reference to  FIGS. 1 through 5 . 
         [0043]    The micro-pump  100  according to the present embodiment may include a bottom substrate  110 , a flow path forming substrate  120 , and a valve substrate  140 . In addition, the micro-pump  100  may further include an actuator  150  if necessary. In this regard, the bottom substrate  110 , the flow path forming substrate  120 , and the valve substrate  140  may be sequentially stacked. 
         [0044]    The bottom substrate  110  may form a base unit of the micro-pump  100 . The bottom substrate  110  may be manufactured formed of a single crystal silicon or 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 insulation members are stacked. 
         [0045]    The flow path forming substrate  120  may be a substrate in which a flow path through which a fluid (for example, a culture medium or drug) is transferred is formed. To this end, an inlet  122  and an outlet  124  may be formed in a first surface (an upper surface in  FIG. 1 ) of the flow path forming substrate  120 , and a pressure chamber  126  may be formed in a second surface (a lower surface in  FIG. 1 ) thereof. In this regard, the pressure chamber  126  may be connected to the inlet  122  and the outlet  124 , and may have a volume capable of accommodating a predetermined amount of fluid therein. 
         [0046]    The flow path forming substrate  120  may be formed of a single crystal silicon or SOI substrate in a similar manner to the case of the bottom substrate  110 . The flow path forming substrate  120  may be integrally formed with the bottom substrate  110  through a firing process. 
         [0047]    The valve substrate  140  may be formed on one surface of the flow path forming substrate  120 , and may control a movement of a fluid flowing through the flow path forming substrate  120 . To this end, the valve substrate  140  may include one or more valves  210  and  220 . 
         [0048]    A first hole  142  and a second hole  144  may be formed in the valve substrate  140 . In this regard, the first hole  142  may be connected to the inlet  122  of the flow path forming substrate  120 , and the second hole  144  may be connected to the outlet  124  thereof. 
         [0049]    The valves  210  and  220  may be installed in the first hole  142  and the second hole  144 , respectively. In more detail, the first valve  210  may be installed in the first hole  142  and the second valve  220  may be installed in the second hole  144 . Meanwhile, valves are installed in both the first hole  142  and the second hole  144  in the present embodiment; however, the valves may be installed only in a single hole if necessary. 
         [0050]    The valve substrate  140  may be formed of a plastic or synthetic resin material. In this case, the valve substrate  140  and the valves  210  and  220  are easily processed, and thus a manufacturing cost of the valve substrate  140  may be reduced. However, if necessary, the valve substrate  140  may be formed of a silicon substrate, while the valves  210  and  220  may be formed of a plastic or synthetic resin material. 
         [0051]    The actuator  150  may be formed on the flow path forming substrate  120 . In more detail, the actuator  150  may be formed on one surface (the upper surface in  FIG. 1 ) of the flow path forming substrate  120 . The actuator  150  may be configured of a lower electrode, a piezoelectric element, and an upper electrode. In more detail, the lower electrode may be formed on an upper surface of the flow path forming substrate  120 , 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 above-configured actuator  150  may generate driving force as the piezoelectric element is modified by a current signal supplied through the upper electrode and the lower electrode. In this regard, the driving force of the actuator  150  is transferred to the pressure chamber  126  of the flow path forming substrate  120 , which may provide a fluid flow. 
         [0052]    Meanwhile, the micro-pump  100  may allow the fluid to flow in one direction through the valves  210  and  220 . This will now be described with reference to  FIGS. 2  though  5 . 
         [0053]    An entrance side (a portion indicated as A of  FIG. 1 ) of the micro-pump  100  may be configured as shown in  FIG. 2 . In more detail, the inlet  122  of the flow path forming substrate  120  may have a first diameter D 1 , and the first hole  142  of the valve substrate  140  may have a second diameter D 2 . In this regard, the first diameter D 1  may be greater than the second diameter D 2 . Meanwhile, a first space  146  in which the first valve  210  may be accommodated may be formed in a lower surface of the valve substrate  140 . 
         [0054]    The first valve  210  may be installed in the first space  146 . The first valve  210  may move upwardly and downwardly in a height direction (in  FIG. 2 ) of the first space  146  and close the first hole  142 . To this end, the first valve  210  may include a plurality of ejection holes  212  as shown in  FIG. 3 . In this regard, a diameter D 6  of a circle with which the plurality of ejection holes  212  come into internal contact may be greater than the second diameter D 2  of the first hole  142 , and a diameter D 5  of a circle with which the plurality of ejection holes  212  come into external contact may be greater than the second diameter D 2  of the first hole  142  but may be smaller than the first diameter D 1  of the inlet  122 . 
         [0055]    In a case in which a fluid moves from the first hole  142  to the inlet  122  in the entrance side of the above-configured micro-pump  100 , the ejection holes  212  are opened as the first valve  210  moves downwardly, and thus the movement of the fluid may be facilitated. However, in a case in which fluid moves from the inlet  122  to the first hole  142 , the first hole  142  may be closed as the first valve  210  moves upwardly, and thus the movement of the fluid may be blocked. 
         [0056]    An exit side (a portion indicated as B of  FIG. 1 ) of the micro-pump  100  may be configured as shown in  FIG. 4 . 
         [0057]    In more detail, the outlet  124  of the flow path forming substrate  120  may have a third diameter D 3 , and the second hole  144  of the valve substrate  140  may have a fourth diameter D 4 . In this regard, the third diameter D 3  may be smaller than the fourth diameter D 4 . Meanwhile, a second space  148  in which the second valve  220  may be accommodated may be formed in the lower surface of the valve substrate  140 . 
         [0058]    The second valve  220  may be installed in the second space  148 . The second valve  220  may move upwardly and downwardly in a height direction (in  FIG. 4 ) of the second space  148  and close the outlet  124 . To this end, the second valve  220  may include a plurality of ejection holes  222  as shown in  FIG. 5 . In this regard, a diameter D 8  of a circle with which the plurality of ejection holes  222  come into internal contact may be greater than the third diameter D 3  of the outlet  124 , and a diameter D 7  of a circle with which the plurality of ejection holes  222  come into external contact may be smaller than the fourth diameter D 4  of the second hole  144 . 
         [0059]    In a case in which fluid moves from the outlet  124  to the second hole  144  in the exist side of the above-configured micro-pump  100 , the ejection holes  222  are opened as the second valve  220  moves upwardly, and thus the movement of the fluid may be allowed. However, in a case in which the fluid moves from the second hole  144  to the outlet  124 , the ejection holes  222  are closed as the second valve  220  moves downwardly, and thus the movement of the fluid may be blocked. 
         [0060]    A direction of fluid movement is controlled by the valves  210  and  220  in the above-configured micro-pump  100 , and thus, advantageously, a small amount of fluid may be uniformly moved. In addition, in the micro-pump  100 , only the valve substrate  140  in which the valves  210  and  220  are formed may be separately manufactured, thereby simplifying a manufacturing process of the micro-pump  100  and reducing a manufacturing cost of the micro-pump  100 . 
         [0061]    Modifications of a valve will now be described with reference to  FIGS. 6 through 13 . A first example of the valves  210  and  220  will now be described with reference to  FIGS. 6 through 8 . 
         [0062]    The first example of the valves  210  and  220  may include a thin film member  10 , a first opening and closing member  20 , and a second opening and closing member  30 . In this regard, the thin film member  10 , the first opening and closing member  20 , and the second opening and closing member  30  may be integrally formed. In more detail, the first opening and closing member  20  and the second opening and closing member  30  may be formed by processing the thin film member  10 . 
         [0063]    The thin film member  10  may be a membrane having a circular cross-section. However, a cross-sectional shape of the thin film member  10  is not limited to a circular shape. For example, the thin film member  10  may have a polygonal cross-section, including a rectangular cross-section. 
         [0064]    The thin film member  10  may be formed of an elastic material. When further explained, the thin film member  10  may be formed of a material which may be bent or deformed when a predetermined degree of force is applied thereto. For example, the thin film member  10  may be formed of a material such as plastic or rubber, or a synthetic resin or metal. However, the material of the thin film member  10  is not limited to the aforementioned materials and the thin film member  10  may be manufactured by any material having a predetermined degree of elastic force. 
         [0065]    The first opening and closing member  20  may be formed in one part of the thin film member  10 . When further explained, the first opening and closing member  20  may be formed in an upper part of the thin film member  10  by a first cutting line  40 . Herein, the first cutting line  40  may be curved to have a first radius R 1 . In this case, the first opening and closing member  20  may have a substantially semicircular shape. However, the shapes of the first opening and closing member  20  and the first cutting line  40  are not limited to shapes illustrated in  FIG. 6 . For example, the first opening and closing member  20  may have a rectangular or triangular shape as illustrated in  FIGS. 7 and 8 , and the first cutting line  40  may be formed as a plurality of straight lines rather than as a curve. 
         [0066]    The first opening and closing member  20  may be opened and closed based on a horizontal line segment L-L. For example, the first opening and closing member  20  may rotate about the horizontal line segment L-L as a central axis. Herein, a rotational direction of the first opening and closing member  20  may depend on locations in which the valves  210  and  220  are installed. 
         [0067]    The second opening and closing member  30  may be formed in the other part of the thin film member  10 . When further explained, the second opening and closing member  30  may be formed in a lower part of the thin film member  10  by a second cutting line  50 . Herein, the second cutting line  50  may be curved to have a second radius R 2 . In this case, the second opening and closing member  30  may have a substantially semicircular shape. However, the shapes of the second opening and closing member  30  and the second cutting line  50  are not limited to shapes illustrated in  FIG. 6 . For example, the second opening and closing member  30  may have the rectangular or triangular shape as illustrated in  FIGS. 7 and 8 , and the second cutting line  50  may be formed as a plurality of straight lines rather than as a curve. 
         [0068]    The second opening and closing member  30  may be opened and closed based on the horizontal line segment L-L in a similar manner to the case of the first opening and closing member  20 . For example, the second opening and closing member  30  may rotate about the horizontal line segment L-L as a central axis. Herein, a rotational direction of the second opening and closing member  30  may be opposite to that of the first opening and closing member  20 . For example, when the first opening and closing member  20  is opened forwardly, the second opening and closing member  30  is opened backwardly while when the first opening and closing member  20  is opened backwardly, the second opening and closing member  30  is opened forwardly. 
         [0069]    The first opening and closing member  20  and the second opening and closing member  30  may respectively have predetermined areas. When further explained, the first opening and closing member  20  may have a first area A 1  and the second opening and closing member  30  may have a second area A 2 . Herein, the first area A 1  of the first opening and closing member  20  may be larger than the second area A 2  of the second opening and closing member  30 . To this end, the length of the first cutting line  40  may be greater than that of the second cutting line  50 . Alternatively, the first radius R 1  of the first cutting line  40  may be larger than the second radius R 2  of the second cutting line  50 . 
         [0070]    As such, when the areas of the first opening and closing member  20  and the second opening and closing member  30  are different from each other, the magnitudes of force acting on the first opening and closing member  20  and the second opening and closing member  30  may be different from each other, which may cause the force to be concentrated on the first opening and closing member  20 , such that the rotation (that is, opening) of the first opening and closing member  20  may be induced. Herein, since the first opening and closing member  20  and the second opening and closing member  30  are integrally formed to move together, the rotation of the first opening and closing member  20  may also induce the rotation of the second opening and closing member  30 . Accordingly, according to the embodiment, the first opening and closing member  20  and the second opening and closing member  30  are opened or closed simultaneously to control the flow of a fluid. 
         [0071]    Meanwhile, a difference in area between the first opening and closing member  20  and the second opening and closing member  30  may depend on a magnitude of the elastic force of the thin film member  10 . For example, when the elastic force of the thin film member  10  is high, the difference in area between the first opening and closing member  20  and the second opening and closing member  30  may be increased and when the elastic force of the thin film member  10  is relatively low, the difference in area between the first opening and closing member  20  and the second opening and closing member  30  may be decreased. The reason for this is that the opening and closing members  20  and  30  may only rotate when force caused by the difference in area between the first opening and closing member  20  and the second opening and closing member  30  is larger than the elastic force of the thin film member  10 . 
         [0072]    For reference, in the embodiment, both ends of the first cutting line  40  and both ends of the second cutting line  50  may be positioned on the horizontal line segment L-L intersecting a center point O. In this case, since rotation reference points of the first opening and closing member  20  and the second opening and closing member  30  are positioned on the same line, the first opening and closing member  20  and the second opening and closing member  30  may smoothly rotate simultaneously. 
         [0073]    The above-configured valves  210  and  220  form the sizes of the first opening and closing member  20  and the second opening and closing member  30  are set to be different from each other, and as a result, opening conditions of the opening and closing members  20  and  30  maybe set. Therefore, even in a pipe through which a small amount of fluid moves, the flow of the fluid may be effectively controlled by controlling the difference in area between the first opening and closing member  20  and the second opening and closing member  30 . 
         [0074]    A second example of the valves  210  and  220  will now be described with reference to  FIGS. 9 through 11 . 
         [0075]    The second example of the valves  210  and  220  may be distinguished from that of the first example in that heights from the center point O of the thin film member  10  to apexes of the cutting lines  40  and  50  are different from each other. That is, a height h 1  from the center point O to the apex of the first cutting line  40  may be different from a height h 2  from the center point O to the second cutting line  50 . 
         [0076]    This structure may naturally induce the difference in area between the first opening and closing member  20  and the second opening and closing member  30 . Moreover, in this structure, since a portion in which the both ends of the first cutting line  40  and the second cutting line  50  are separated from each other serves as a rotational shaft, the first opening and closing member  20  and the second opening and closing member  30  may smoothly rotate. 
         [0077]    Meanwhile, the shapes of the first opening and closing member  20  and the second opening and closing member  30  may be deformed as illustrated in  FIGS. 10 and 11 , and to this end, the first cutting line  40  and the second cutting line  50  may be formed by the plurality of straight lines. 
         [0078]    A third example and a fourth example of the valves  210  and  220  will now be described with reference to  FIGS. 12 and 13 . 
         [0079]    The third example of the valves  210  and  220  may be distinguished from those of the foregoing examples in that the valves  210  and  220  include third cutting lines  60  and fourth cutting lines  70 . 
         [0080]    The third example of the valves  210  and  220  may further include the third cutting lines  60 . The third cutting lines  60  may extend inwardly in a direction toward the center point O from both ends of the first cutting line  40 . The third cutting lines  60  are not connected to the second cutting line  50 , but may be positioned on the same line as both ends of the second cutting line  50 . 
         [0081]    In the valves  210  and  220  formed as above, since a connection length L 1  between the thin film member  10  and the first opening and closing member  20  is shortened by the third cutting lines  60 , the first opening and closing member  20  may be more smoothly moved. 
         [0082]    The fourth example of the valves  210  and  220  may further include the third cutting lines  60  and the fourth cutting lines  70 . The third cutting lines  60  may extend inwardly from both ends of the first cutting line  40  and the fourth cutting lines  70  may extend outwardly from both ends of the second cutting line  50 . Herein, since both ends of the first cutting line  40  and both ends of the second cutting line  50  are formed to be separated from each other by a predetermined interval, the third cutting lines  60  and the fourth cutting lines  70  may not be connected to each other. 
         [0083]    In the valves  210  and  220  formed as above, since a shaft  16 , a rotation reference of the first opening and closing member  20  and the second opening and closing member  30  is formed by the third cutting lines  60  and the fourth cutting lines  70 , the first opening and closing member  20  and the second opening and closing member  30  may smoothly rotate. 
         [0084]    The micro-pump  100  according to another embodiment of the present invention will now be described with reference to  FIG. 14 . For reference, the same elements between another embodiment and the above-described embodiments denote the same reference numerals, and detailed descriptions thereof will be omitted here. 
         [0085]    The micro-pump  100  according to another embodiment may be distinguished from the above-described embodiment in terms of the flow path forming substrate  120  and a vibration substrate  130 . 
         [0086]    The flow path forming substrate  120  may include the inlet  122 , the outlet  124 , and the pressure chamber  126  in like manner to the above-described embodiment. However, the pressure chamber  126  according to the embodiment may be completely open in a vertical direction, unlike the above-described embodiment. The pressure chamber  126  having the above shape may be easily formed by an etching process (in particular, a wet etching process). A size and volume of the pressure chamber  126  may be easily changed by adjusting a thickness of the flow path forming substrate  120 . 
         [0087]    The vibration substrate  130  may be coupled to the flow path forming substrate  120 . The vibration substrate  130  may be formed of a single crystal silicon or SOI substrate. Through holes  132  and  134  may be formed in the vibration substrate  130 . In this regard, the first through hole  132  may connect the inlet  122  and the first hole  142 , and the second through hole  134  may connect the outlet  124  and the second hole  144 . 
         [0088]    In the above-configured micro-pump  100 , the flow path forming substrate  120  may be easily manufactured through an etching process. In addition, the vibration substrate  130  is separately manufactured, such that the slimness of the vibration substrate  130  may be facilitated, thereby reducing current consumption required for driving the actuator  150 . 
         [0089]    As set forth above, according to embodiments of the invention, a fluid including a fine material, for example, a micro-material can be effectively transferred. 
         [0090]    In addition, according to embodiments of the invention, a micro-pump can separately manufacture a valve substrate, thereby simplifying a manufacturing process of the micro-pump and reducing a manufacturing processing cost. 
         [0091]    While the present invention has been shown and described in connection with the embodiments, it will be apparent to those skilled in the art that modifications and variations can be made without departing from the spirit and scope of the invention as defined by the appended claims.