Abstract:
A micropump and a disposable pump body thereof are disclosed. The micropump includes the pump body and an actuator device. The pump body includes a chamber, an inlet communicating with the chamber, an outlet communicating with the chamber and a covering membrane on top of the chamber. The actuator device includes an actuator and a transmitting post. One of the two ends of the transmitting post connects to the actuator. The other end of the transmitting post abuts against the membrane. Since the pump body is separated from the actuator device, the pump body is disposable and can be replaced after use to avoid cross-infection of disease, particularly useful for medical liquid delivery.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
       [0001]    This non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No. 102134612 and 103212139, filed in Taiwan, R.O.C. on 2013 Sep. 25 and 2014 Jul. 8, the entire contents of which are hereby incorporated by reference. 
       BACKGROUND 
       [0002]    1. Technical Field 
         [0003]    The disclosure relates to a micropump, and particularly to a micropump with a separated pump body. 
         [0004]    2. Related Art 
         [0005]    A conventional micropump structure has a membrane positioned on the top of a pump body, and an actuator mounted on the top of the membrane in integral. Typically, the actuator is a piezoelectric (PZT) plate. 
         [0006]    In the micro electric mechanical engineering field, the micro fluid-detection and control components are widely used in the precision and automation industry. Particularly in the biomedical field, a used component should be discarded if part of it is in direct contact with body fluids, so as to prevent cross infection or detection errors. 
         [0007]    However, the actuator and the membrane of the conventional micropump are integrated, consequently, when the membrane and pump body are discarded, the expensive actuator is also abandoned at the same time. Consequently, the conventional micropump is highly expensive, a problem requiring a solution. 
       SUMMARY 
       [0008]    In view of this, the present invention provides a micropump with a separated pump body. This invention can efficiently solve the problem of high cost, while avoiding cross-infection. 
         [0009]    This invention provides a micropump including a pump body and an actuator device. 
         [0010]    The pump body includes a chamber, an inlet communicating with the chamber, an outlet communicating with the chamber and a covering membrane on the top of the chamber. The inlet and the outlet both communicate with the chamber on the opposite sides. 
         [0011]    The actuator device abuts against the membrane. The actuator device includes an actuator and a transmitting post. The transmitting post extends a first end connected to the actuator and a second end abutting against the membrane. 
         [0012]    The actuator drives the transmitting post to swing downwardly and upwardly, so as to depress the membrane to compress the volume of the chamber when downwards, and to recover the membrane to resume the volume of the chamber when upwards. 
         [0013]    Since the pump body is separated from the actuator device, the pump body is disposable and can be replaced with a new one after use. Particularly when using in the medical field or when delivering body fluids, the disposable pump body of the micropump of this invention could avoid cross-infection of disease. 
         [0014]    In one embodiment of the present invention, the first end of the transmitting post has a greater cross section area than that of the second end. Consequently, the transmitting post is easy to locate at the correct position on the membrane. 
         [0015]    This invention also provides a pump body including a chamber, an inlet and an outlet both communicating with the chamber on the opposite sides, and a covering membrane on the top of the chamber. The pump body is disposable and can be replaced each time after use, but the expensive actuator device of the micropump can be reused more than once. Consequently, this invention could reduce the cost of each use of the micropump. 
         [0016]    In one embodiment of the present invention, the membrane includes a first region corresponding to a top opening of the chamber, and a second region which encircling or surrounding the first region, wherein the first region having a higher top surface than that of the second region. Consequently, the deformation of the membrane occurs near the second region, which would enhance the resilience of the membrane when the transmitting post depresses the membrane, and the entire first region compresses the volume of the chamber, which would increase the volume change of the chamber and improve the micropump efficiency. 
         [0017]    In one embodiment of the present invention, the transmitting post abuts against the first region of the membrane. The thickness of the first region is increased, and the transmitting post depresses the first region of the invention. This eliminates the problem caused by the traditional micropump in which the traditional actuator covers the membrane with viscose, the actuator impacts the membrane directly, and the membrane breaks down easily, shortening the lifetime of micropump. 
         [0018]    In one embodiment of the present invention, the area of the first region is greater than or equal to 50% of the area of a top opening of the chamber. In another embodiment of the present invention, the area of the first region is greater than or equal to 66.7% of the area of the top opening of the chamber. In the other embodiment of the present invention, the area of the first region is between 66.7˜80% of the area of the top opening of the chamber. When the transmitting post moves downward to depress the membrane with the same force, the less deformation in the first region could cause the more volume change in the chamber. Consequently, this invention could improve the efficiency of the micropump. 
         [0019]    In one embodiment of the present invention, the membrane is made from Polydimethyl siloxane (PDMS) material. The first region has a double thickness of that of the second region, which would result in more significantly different deformation between the first region and the second region. 
         [0020]    In one embodiment of the present invention, the thickness of the second region is greater than 0.2 mm. In another embodiment of the present invention, the thickness of the second region is preferably between 0.3-0.5 mm. If the thickness of the membrane is insufficient, the membrane will not spring back or recover, due to lack of resilience. 
         [0021]    The detailed features and advantages of the disclosure are described below in great detail through the following embodiments; the content of the detailed description is sufficient for those skilled in the art to understand the technical content of the disclosure and to implement the disclosure there accordingly. Based on the content of the specification, the claims, and the drawings, those skilled in the art can easily understand the relevant objectives and advantages of the disclosure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    The disclosure will become more fully understood from the detailed description given herein below for illustration only, and thus not limitative of the disclosure, wherein: 
           [0023]      FIG. 1  is an exploded view of a micropump of a first embodiment of the disclosure; 
           [0024]      FIG. 2  is an exploded view of the pump body of the first embodiment of the disclosure; 
           [0025]      FIG. 3  is a sectional view of the chamber of the first embodiment of the disclosure; 
           [0026]      FIG. 4  is a sectional view of the pump body of the disclosure; 
           [0027]      FIG. 5  is a schematic view of the micropump is recovered from the disclosure; 
           [0028]      FIG. 6  a schematic view of the micropump is compressed of the disclosure; 
           [0029]      FIG. 7  is a schematic view of a micropump of a second embodiment of the disclosure; 
           [0030]      FIG. 8  is an exploded view of a micropump of a second embodiment of the disclosure; 
           [0031]      FIG. 9  is a sectional view of a micropump of a second embodiment of the disclosure; 
           [0032]      FIG. 10  is a flow rate chart of 2a=7.5 mm of the disclosure; and 
           [0033]      FIG. 11  is a flow rate chart of 2a=10 mm of the disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0034]    Please refer to  FIG. 1 , which is an exploded view of a micropump of a first embodiment of the disclosure. As shown, the micropump includes a pump body  1  and an actuator device  9 . 
         [0035]    The actuator device  9  abuts against the membrane  13 . The actuator device  9  includes an actuator  91  and a transmitting post  92 . The transmitting post  92  extends a first end  92 - 1  connected to the actuator and a second end  92 - 2  abutting against the membrane  13 . The actuator  91  is the power source of the micropump. The actuator  91  can be choosing from many elements based on different theorem. For example, Piezoelectric, Electrostatic, Thermo pneumatic, Electromagnetic and Shape memory alloy. In the first embodiment of the disclosure, the actuator  91  is a piezoelectric plat. The piezoelectric material has good performance of converting the electricity to the mechanical energy. 
         [0036]    A micropump usually refers to a pump has a very small chamber radius size between (or below), 2.5 mm˜7.5 mm. As a result of the small size, the process to make the pump body is not easy. Therefore, in this embodiment, the first step of the manufacturing process, cutting (for example, etching or laser cutting) out of the appropriate shape on each substrate, and then combining said substrates to from the pump body. The substrate may choose from different material (for example, plastic or stainless steel.). 
         [0037]    Please refer to  FIG. 2 , which is an exploded view of the pump body of the first embodiment of the disclosure. The pump body  1  includes a first substrate  14 , a second substrate  15  and a membrane  13 . The first substrate  14  includes a chamber  10  as a through-hole, a first section inlet  11   a  and a first section outlet  12   a.  The second substrate  15  includes a second section inlet  11   b  and a second section outlet  12   b.    
         [0038]    The first substrate  14  and the second substrate  15  are to combine to form the pump body, so that the first section inlet  11   a  communicates with the second section inlet  11   b  to from an inlet  11 . The inlet  11  communicates with the chamber  10 . Similarly, the first section outlet  12   a  communicates with the second section outlet  12   b  to from an outlet  12 . The outlet  12  communicates with the chamber  10 . The membrane  13  covered on top of the chamber  10 . 
         [0039]    Please refer to  FIG. 3 , which is a sectional view of the chamber of the first embodiment of the disclosure. The first section inlet  11   a  have large caliber of the end near by the chamber  10 , and the other end of the first section inlet  11   a  have small caliber. Conversely, the first section outlet  12   a  have small caliber of the end near by the chamber  10 , and the other end of the first section outlet  12   a  have large caliber. This kind of design is “direction dependent flow resistance”, also call “diffuser/nozzle”. 
         [0040]    The actuator  91  drives the transmitting post  92  to swing up and down. When the transmitting post  92  moves downward to press the membrane  13 , the volume of the chamber  10  is compressed, and the internal pressure of the chamber  10  is increased. Therefore, the fluid inside the chamber  10  would be squeezed out to both the inlet  11  and the outlet  12 , respectively. For the directional arrangement of the first section inlet  11   a  and first section outlet  12   a  (referred to  FIG. 3 ), so as the fluid amount leaving the chamber  10  through the inlet  11  would be less than the fluid amount leaving the chamber  10  through the outlet  12 . Consequently, the fluid inside the chamber  10  is output through the outlet  12 . 
         [0041]    Conversely, when the transmitting post  92  moves upward to recover the membrane  13 , the volume of the chamber  10  is recovered, and the internal pressure of the chamber  10  is decreased. Therefore, the fluid is input through the inlet  11  to the chamber  10 . 
         [0042]    Please refer to  FIG. 5 , which is a schematic view of the micropump recovered from the disclosure. The membrane  13  includes a first region  131  and a second region  132  around the first region  131 , and a top surface of the first region  131  is higher than a top surface of the second region  132 . 
         [0043]    Please refer to  FIG. 6 , which is a schematic view of the micropump compressed from the disclosure. Since the first region  131  is thicker than the second region  132 , the deformation of the first region  131  is smaller than the second region  132 . Since the transmitting post  92  moves downward to press the membrane  13 , the deformation of the membrane  13  focused on the second region  132 . Consequently, the resilience of the membrane  13  has been raised, the volume change of the chamber  10  has been increased, and the efficiency of the micropump has been improved. 
         [0044]    The membrane  13  and the chamber  10  form an enclosed space (as shown in  FIG. 5 ), the volume of the enclosed space is B, so we can also say that the volume of the chamber  10  is B. When the transmitting post  92  moves downward to press the membrane  13 , the volume of the chamber is B′ (as shown in  FIG. 6 ). The efficiency formula is B-B′=R, where R is one of the ways to represent the efficiency of the micropump. 
         [0045]    Since the deformation of the first region  131  is smaller than the second region  132 , so the R of the present invention is bigger than the R of the conventional micropump. In other words, in the present invention each swing of the actuator generates a greater volume change than the conventional micropump. This means the same number of swings can result in a greater flow rate. 
         [0046]    Please refer to  FIG. 7 , which is a schematic view of a micropump of a second embodiment of the disclosure. The transmitting post  92  has a greater surface area at the end connected the actuator  92 - 1 , the transmitting post  92  has a smaller surface area at the end against the membrane  92 - 2 . The power generated from the actuator  92  has a large area, is converted to the membrane  13 , which has a small area. Consequently, the micropump can complete the pumping action using the power generated by the actuator. Meanwhile, the transmitting post  92  can fix the position of the first region  131  correctly and easily. 
         [0047]    Please refer to  FIG. 8 , which is an exploded view of a micropump of a second embodiment of the disclosure. The shape of the first substrate  14  is a cylinder. There is a cavity on the top surface of the first substrate  14 ; is the cavity is chamber  10 . The inner wall of chamber  10  is a stair structure. From bottom to top, the inner wall is defined as a bottom-surface  14   c,  a second-surface  14   b  and a top-surface  14   c.  The inlet  11  and the outlet  12  connect to the bottom-surface  14   c,  respectively. 
         [0048]    Please refer to  FIG. 9 , which is a sectional view of a micropump of a second embodiment of the disclosure. A size of the membrane  13  is larger than the bottom-surface  14   c,  but fits within the second-surface  14   b.  The membrane  13  is fixed on the top surface of the second-surface  14   b  and surrounded by the top-surface  14   c,  thus membrane  13 . The membrane  13  includes the first region  131  and the second region  132  around the first region  131 . In the other words, the second region  132  located in the center of the membrane  13 . The membrane  13  could be one piece, but it is to be understood that the invention need not be limited to the disclosed embodiments. The membrane  13  could be combined with two pieces having different thicknesses or different materials. 
         [0049]    The second substrate  15  includes an inlet valve  151  and a outlet valve  152 . The inlet valve  151  can prevent fluid outflow from the inlet  11 . The outlet valve  152  can prevent fluid inflow through the outlet  12 . Keeping the fluid unidirectional improves the performance of the micropump. 
         [0050]    The inlet valve  151  is embedded into a surface of the second substrate  15  which is near the first substrate  14 . The outlet valve  152  is embedded into a surface of the first substrate  14 , which fairs from the chamber  10 . 
         [0051]    The performance of the micropump relates to the first region  131 , the second region  132  and the size of the chamber  10 . The following paragraphs will discuss these elements. 
         [0052]    The area of the first region  131  is greater than or equal to one half, which is  50 % of the area of the top opening of the chamber  10 . To raise the performance of the micropump, the area of the first region  131  must be of sufficient size. Under optimal conditions, the area of the first region  131  is greater than or equal to two third, which is percentage of 66.7%, of the area of the top opening of the chamber  10 . Under optimal conditions, the area of the first region  131  is between two third to four fifth, which is in percentage of 66.7˜80%, of the top surface area of the chamber  10 . 
         [0053]    Please refer to  FIG. 4 , which is a sectional view of the pump body of the disclosure. In the embodiment of the present invention, the membrane  13  is a round-shape. Therefore, the following discussion will concern a radius “a” of the chamber  10  and a radius “b” of the first region  131 . First, obtain a measured data as shown in  FIG. 10  using the micropump with a chamber diameter (2a) of 7.5 mm. The X-axis of the chart represents the vibration frequency of the PZT plat (as the actuator  91 ), is 0 Hz to 140 Hz. The Y-axis represents the flow-rate of the micropump is 0 to 25 (g/min). The curve with symbol of “▾” represents a diameter (2b) of the first region is 7 mm. The curve “◯” represents a diameter (2b) of the first region is 6 mm. The curve with symbol of “” represents a diameter (2b) of the first region is 5.25 mm. When the radius ratio (b/a) is between 0.6 to 0.8, the performance of the micropump is good enough. However, if the radius ratio (b/a) is greater than 0.8, such as the curve with symbol of “▾”, of which the radius ratio (b/a) is 0.933, the micropump performance is reduced. 
         [0054]    A second measured data as shown in  FIG. 11  using the micropump with a chamber diameter (2a) of 10 mm. We can also obtain similar results as shown in  FIG. 10 . 
         [0055]    In the embodiment of the present invention, the membrane  13  is made of a PDMS (Polydimethyl siloxane), material. In the other embodiment of the present invention, the membrane  13  can also be made of PI, silica gel, PE, metal film and any other elastic material. 
         [0056]    In the embodiment of the present invention, the thickness of the first region  131  is twice or more than twice the thickness of the second region  132 . If the first region  131  is too thin, the first region  131  would be broken upon being impacted by the transmitting post  92 . 
         [0057]    In the embodiment of the present invention, if the thickness of the second region  132  is too great, the PZT plat would not have enough power to press downward the membrane  13 . If the thickness of the second region  132  is too small, when the PZT plat leaves the membrane  13 , it could not recover by itself and the micropump performance will be reduced. Consequently, the thickness of the second region  132  is greater than 0.2 mm. Under optimal conditions, the thickness of the second region is between 0.3-0.5 mm. If the thickness of the membrane  13  is insufficient, then the resilience of the membrane will also be insufficient. 
         [0058]    While the disclosure has been described by the way of example and in terms of the preferred embodiments, it is to be understood that the invention need not be limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims, the scope of which should be accorded the broadest interpretation so as to encompass all such modifications and similar structures.