US20150086397A1

US20150086397A1 - Micropump with separate chamber

Info

Publication number: US20150086397A1
Application number: US14/491,105
Authority: US
Inventors: Hsiao-Kang Ma
Original assignee: Individual
Current assignee: Individual
Priority date: 2013-09-25
Filing date: 2014-09-19
Publication date: 2015-03-26

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

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

1. Technical Field
The disclosure relates to a micropump, and particularly to a micropump with a separated pump body.
2. Related Art
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.
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.
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

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.
This invention provides a micropump including a 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 the top of the chamber. The inlet and the outlet both communicate with the chamber on the opposite sides.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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

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:

FIG. 1 is an exploded view of a micropump of a first embodiment of the disclosure;

FIG. 2 is an exploded view of the pump body of the first embodiment of the disclosure;

FIG. 3 is a sectional view of the chamber of the first embodiment of the disclosure;

FIG. 4 is a sectional view of the pump body of the disclosure;

FIG. 5 is a schematic view of the micropump is recovered from the disclosure;

FIG. 6 a schematic view of the micropump is compressed of the disclosure;

FIG. 7 is a schematic view of a micropump of a second embodiment of the disclosure;

FIG. 8 is an exploded view of a micropump of a second embodiment of the disclosure;

FIG. 9 is a sectional view of a micropump of a second embodiment of the disclosure;

FIG. 10 is a flow rate chart of 2a=7.5 mm of the disclosure; and

FIG. 11 is a flow rate chart of 2a=10 mm of the disclosure.

DETAILED DESCRIPTION

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.
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.
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.).
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.
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.
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”.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.

Claims

What is claimed is:

1. A micropump comprising:

a pump body, said pump body comprising a chamber therein, an inlet and an outlet both communicating with the chamber on the opposite sides, and a covering membrane on the top of the chamber; and

an actuator device, said actuator device comprising an actuator and a transmitting post having a first end connected to the actuator and a second end abutting against the membrane;

wherein 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.

2. The micropump according to claim 1, wherein the first end of the transmitting post has a greater cross section area than that of the second end.

3. The micropump according to claim 1, wherein the membrane comprising a first region and a second region surrounding the first region, wherein the first region has a top surface higher than that of the second region.

4. The micropump according to claim 3, wherein the transmitting post abuts against the first region of the membrane.

5. The micropump according to claim 3, wherein the area of the first region is greater than or equal to 50% of the area of a top opening of the chamber.

6. The micropump according to claim 3, wherein the area of the first region is greater than or equal to 66.7% of the area of a top opening of the chamber.

7. The micropump according to claim 3, wherein the area of the first region is between 66.7%˜80% of the area of a top opening of the chamber.

8. The micropump according to claim 3, wherein the membrane is made from Polydimethyl siloxane (PDMS) material.

9. The micropump according to claim 3, wherein the first region has a double thickness of that of the second region.

10. The micropump according to claim 9, wherein the thickness of the second region is greater than 0.2 mm.

11. The micropump according to claim 10, wherein the thickness of the second region is between 0.3-0.5 mm.

12. A pump body, comprising:

a chamber therein;

an inlet and an outlet both communicating with the chamber on the opposite sides; and

a covering membrane on the top of the chamber.

13. The pump body according to claim 12, wherein the membrane comprising a first region and a second region surrounding the first region, wherein the first region has a top surface higher than that of the second region.

14. The pump body according to claim 13, wherein the area of the first region is greater than or equal to 50% of the area of a top opening of the chamber.

15. The pump body according to claim 13, wherein the area of the first region is greater than or equal to 66.7% of the area of a top opening of the chamber.

16. The pump body according to claim 13, wherein the area of the first region is between 66.7˜80% of the area of a top opening of the chamber.

17. The pump body according to claim 12, wherein the membrane is made from Polydimethyl siloxane (PDMS) material.

18. The pump body according to claim 13, wherein the first region has a double thickness of that of the second region.

19. The pump body according to claim 13, wherein the thickness of the second region is greater than 0.2 mm.

20. The pump body according to claim 13, wherein the thickness of the second region is between 0.3-0.5 mm.