US20090010767A1

US20090010767A1 - Electric comb driven micropump system

Info

Publication number: US20090010767A1
Application number: US11/774,543
Authority: US
Inventors: Yaw-Jen Chang; Ming-Cheng Shiu
Original assignee: Chung Yuan Christian University
Current assignee: Chung Yuan Christian University
Priority date: 2007-07-06
Filing date: 2007-07-06
Publication date: 2009-01-08

Abstract

An electric comb driven micropump system includes a piston, a comb actuator comb and a real-time monitoring device. The comb actuator may generate an electrostatic force after receiving a voltage, so as to actuate the piston to make a first displacement, which causes a fluid to enter into a cavity, wherein the voltage has a voltage value for determining the volume of the fluid entering into the cavity, and wherein as the voltage value of the voltage gradually decreases, the electrostatic forces also decreases, allowing the piston to gradually make a second displacement in a direction opposite to the first displacement driven by a spring, thus outputting the fluid from the cavity. The real-time monitoring device provides real-time information of the comb actuator.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention generally relates to a pump technique, more specifically, a micropump.
2. Description of the Prior Art
Currently, the most commonly seen micropump is valve-less micropump, which primarily uses an actuator to generate vibrations of a membrane, causing changes in volume of a cavity. The inlet and outlet are designed as diffusers/nozzles, the shape thereof controls the fluid input/output pressures However, current valve-less pumps can only control an average flow quantity, but not each output quantity. In applications of biomedical testing, no quantitative testing can be achieved.
Various researches have been done focusing on changing actuating source materials, the cavity design or valve-type pump etc. For micropump system, Shen-Jian Yang et al. discloses, in TW Patent No. 00568881 titled “Programmable capacitive micropump”, a flat rectangular micro-channel cavity. Top and bottom sides (or just the top side) of the cavity are covered with a elastic membrane plated with a plurality of linear (grid-shaped) metal electrodes. Applying to each grid-shaped electrode an appropriate actuating voltage with a phase difference, capacitive electrostatic attraction force generated between the grid-shaped electrodes and the bottom electrode of the cavity as well as elastic membrane restoring force drives the elastic membrane to generate several propagating waves in a single direction, that is, the elastic membrane pushes fluid in a squirming motion, allowing the micropump to operate smoothly and effectively.
In TW Patent No. 00324948 titled “electromagnetically actuated micropump” by Shi-Chu Chen, an electromagnetically actuated micropump is proposed, which is fabricated by micromachining technique in order to accurately manipulate microfluid. The micropump has back-and-forth motions due to electromagnetic actuation in cooperation with valve-less inlet/outlet. Magnetic forces are generated by a planar coil in conjunction with a soft magnet or a permanent magnet on the same vertical plane. The coil is deposited on a membrane as a moving element, while the magnet acts as a stationary element, or the coil as a stationary element and the magnet as the moving element, or two sets of coils are used to generate the back-and-forth motions. The design of the inlet/outlet adopts diffuser/nozzle elements instead of the traditional check valves. The micropump having such composition has several advantages, such as fast reaction, low input voltage, easy inlet/outlet fabrication process and high reliability.
However, the abovementioned micropump systems are all valve-less, which lacks quantitative output control. Commonly seen piezoelectric valve-less micropump utilizes piezoelectric plate as the actuating source, that is, according to the vibrating principle of the piezoelectric plate, the membrane is vibrated, causing change in cavity volume, so that fluid may flow in to/ out of the cavity via the diffusers/nozzles. This is more or less similar to the abovementioned principle that outputs fluid by change in cavity volume. This kind of method also requires the design of the diffusers/nozzles to control fluid output, but not the quantity of the fluid outputted.

SUMMARY OF THE INVENTION

In view of the prior art and the needs of the related industries, the present invention provides that solves the abovementioned shortcomings of the conventional.
One objective of the present invention is to design an electric comb driven micropump system that achieves quantitative fluid output, which is different from the traditional micropump that continuously but not quantitatively outputs fluid, thus it can be widely used in biochemical reactions, specimen mixing, lab chips, biological chip quantitative testing, and various related applications of fluid dynamics.
In view of this and other objectives, the present invention provides an electric comb driven micropump system, which includes a piston, a comb actuator comb and a real-time monitoring device. The comb actuator may generate an electrostatic force after receiving a voltage, so as to actuate the piston to make a first displacement, which causes a fluid to enter into a cavity, wherein the voltage has a voltage value for determining the volume of the fluid entering into the cavity, and wherein as the voltage value of the voltage gradually decreases, the electrostatic forces also decreases, allowing the piston to gradually make a second displacement in a direction opposite to the first displacement driven by a spring, thus outputting the fluid from the cavity. The real-time monitoring device provides real-time information of the comb actuator.
By using the above electric comb driven micropump system, fluid can be outputted in fixed quantity desired for testing. Fluid in the cavity can be pushed out by the piston, thus achieving quantitative output control.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention, and together with the description serve to explain the principles of the disclosure. In the drawings:

FIG. 1 is a cross-sectional schematic diagram of a micropump according to a first preferred embodiment of the present invention;

FIGS. 1 to 3 are schematic diagrams illustrating the actuating method of a micropump according to a second preferred embodiment of the present invention;

FIG. 4 is a bottom schematic view of the micropump structure according to FIG. 2 of the second preferred embodiment of the present invention;

FIG. 5 is a bottom schematic view of the micropump structure according to FIG. 3 of the second preferred embodiment of the present invention; and

FIG. 6 is a schematic diagram of an electric comb driven micropump system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention are described below in conjunction with appended drawings to better understand the above and other objectives, features and advantages of the present invention.
FIG. 1 is a cross-sectional schematic diagram of a micropump according to a first preferred embodiment of the present invention. Referring to FIG. 1, the micropump at least comprises a piston 10 and a comb actuator 20. The comb actuator 20 may generate an electrostatic force after receiving a voltage from a power supply 98 (FIG. 6), so as to actuate the piston 10 to make a first displacement 12, which causes a fluid 30 (FIG. 2) to enter into a cavity 40. The fluid 30 is a sample or a reagent, for example.
The abovementioned voltage has a voltage value that determines the volume of fluid 30 entering into the cavity 40. As the voltage value of this voltage gradually decreases, the electrostatic forces also decreases, allowing the piston to gradually make a second displacement 14 (FIG. 3) in a direction opposite to the first displacement 12 driven by a spring 70, thus outputting the fluid 30 from the cavity 40. In this way, the quantity of output of the fluid 30 can be accurately controlled.
The micropump of the first preferred embodiment of the present invention may further comprise a voltage control device 80 (e.g. a relay) for gradually reducing the voltage value. The voltage control device 80 may also be used to change the voltage value so as to change the volume of fluid flowing into the cavity. By using this voltage control device 80, the micropump of the present invention is able to control the quantity of each output. In applications of biomedical testing, the micropump of the present invention can provide quantitative specimen.
The cavity 40 of the first preferred embodiment of the present invention may be a valve-less cavity. As for the fluid 30, it may be passed through an inlet 32 into the cavity 40. Moreover, the fluid 30 inside the cavity 40 can be outputted via an outlet 34.
There can be a specific angle between the entering direction of the inlet 32 and the exit direction of the outlet 34, such that the flowing direction of the fluid 30 can be controlled. The specific angle may, for example, be 90 degrees. The exit direction of the outlet 34 is the direction of the second displacement 34 of the piston 10. The micropump may further comprise a fluid supply and control device connected to a guiding joint. The fluid supply and control device may provide a fixed pressure for driving the fluid in the micropump loop to move in a certain direction. The loop refers to a channel of the micropump in which the fluid flows.
FIG. 6 depicts a schematic diagram of an electric comb driven micropump system. Referring to FIG. 6, the comb actuator 20 may be connected to a real-time monitoring device 92 for real-time monitoring of the exterior. This real-time monitoring device 92 may directly monitor the fluid in the micropump loop so as to provide real-time information to the comb actuator 20. More specifically, the real-time monitoring device provides real-time information by an analog/digital converter 94 (AD/DA converter) and a computer 96. Based on the real-time information, the voltage control device 80 can determine the voltage value, and in turn the volume of fluid to be entered into the cavity 40 (FIG. 1).
Referring now to FIGS. 4 and 5, the micropump of the first preferred embodiment is voltage driven, that is, the displacement of the electric comb is controlled based on a relationship of the voltage and the electrostatic force. The fluid is externally driven directly into the valve-less cavity, then the displacement of the electric comb is controlled by varying the voltage, driving the piston 10 to output the fluid 30 inside the cavity 40. The micropump eliminates the problem of the valve-less micropump being not able to control the quantity of output. Since the output of the micropump is a total output, thus the droplet phenomenon can be improved.
The design of the micropump permits the microfluid to be outputted by a fixed quantity required for testing. Using principles of diffusers and nozzles, as well as a driving source, the micropump performs piston type back-and-forth movement, such that the fluid 30 in the cavity 40 is pushed out therefrom by the piston 10 to obtain the required quantity of output.
According to the first preferred embodiment, the present invention can be widely applied to biochemical reactions, specimen mixing, lab chips, biological chip quantitative testing, and various related applications of fluid dynamics. In addition, the present invention employs external voltage and pressure control devices and real-time monitoring device for real-time monitoring reaction status and controlling voltage and output, thus eliminating the shortcoming that traditional chips can only output continuously. The valve-less cavity design also reduces difficulties in controlling and manufacturing cost.
FIGS. 1 to 3 are schematic diagrams illustrating the actuating method of a micropump according to a second preferred embodiment of the present invention. Referring to FIG. 1, the first step includes guiding a fluid 30, by an external fixed driving pressure, via a guiding joint to a temporary tank 90, such that the fluid 30 fills up the tank 90.
FIG. 4 is a bottom schematic view of the micropump structure according to FIG. 2 of the second preferred embodiment of the present invention. Referring to FIGS. 2 and 4, the second step includes applying a voltage to a comb actuator 20 to generate an electrostatic force, which actuates a piston 10 to make a first displacement 12, allowing the fluid 30 to enter into a cavity 40, wherein the voltage has a voltage value for determining the volume of the fluid 30 entering into the cavity 40.
Referring to FIGS. 2 and 4, when the voltage value increases, the electrostatic force generated increases, and in turn the displacement of the piston 10 increases accordingly. The first displacement 12 of the piston is for example an upward movement from the bottom of the cavity 40 (FIG. 4; left movement in FIG. 2). Meanwhile, pressure in the cavity 40 varies. When the front end of the piston 10 moves to the inlet 32, the cavity will quickly fill up with the fluid 30 due to pressure variation in the cavity 40, as shown in FIG. 2.
FIG. 5 is a bottom schematic view of the micropump structure according to FIG. 3 of the second preferred embodiment of the present invention. Referring to FIGS. 3 and 5, in the third step, voltage value is gradually decreased, so as the electrostatic force, allowing the piston 10 to gradually make a second displacement 14 in a direction opposite to the first displacement 12 driven by a spring 70, thus outputting the fluid 30 from the cavity 40.
The driving voltage applied on the comb actuator 20 gradually decreases, and the comb actuator 20, under the influence of the spring and gradually weakened electrostatic force, drives the piston to make the second displacement 14, for example, move downward (FIG. 5; move left in FIG. 3). When the piston 10 moves downward, the fluid 30 is pushed outside of the cavity 40.
In the second preferred embodiment of the present invention, the above actuating method may further comprise a changing step for changing the voltage value, so as to change the volume of fluid entering into the cavity.
The cavity 40 of the second preferred embodiment of the present invention may be a valve-less cavity. As for the fluid 30, referring to FIG. 2, it may be passed through an inlet 32 into the cavity 40. Moreover, the fluid 30 inside the cavity 40 can be outputted via an outlet 34.
There can be a specific angle between the entering direction of the inlet 32 and the exit direction of the outlet 34, such that the flowing direction of the fluid 30 can be controlled. The specific angle may, for example, be 90 degrees. The exit direction of the outlet 34 is the direction of the second displacement 34 of the piston 10.
According to the second preferred embodiment, the present invention can be widely applied to biochemical reactions, specimen mixing, lab chips, biological chip quantitative testing, and various related applications of fluid dynamics. In addition, the present invention employs external voltage and pressure control devices and real-time monitoring device for real-time monitoring reaction status and controlling voltage and output, thus eliminating the shortcoming that traditional chips can only output continuously. The valve-less cavity design also reduces difficulties in controlling and manufacturing cost.
The foregoing description is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obvious modifications or variations are possible in light of the above teachings. In this regard, the embodiment or embodiments discussed were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the inventions as determined by the appended claims when interpreted in accordance with the breath to which they are fairly and legally entitled.
It is understood that several modifications, changes, and substitutions are intended in the foregoing disclosure and in some instances some features of the invention will be employed without a corresponding use of other features. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.

Claims

1. An electric comb driven micropump system, including:

a piston;

a comb actuator comb for generating an electrostatic force after receiving a voltage, so as to actuate the piston to make a first displacement, which causes a fluid to enter into a cavity, wherein the voltage has a voltage value for determining the volume of the fluid entering into the cavity, and wherein as the voltage value of the voltage gradually decreases, the electrostatic forces also decreases, allowing the piston to gradually make a second displacement in a direction opposite to the first displacement driven by a spring, thus outputting the fluid from the cavity; and

a real-time monitoring device for providing real-time information of the comb actuator.

2. An electric comb driven micropump system of claim 1, further including a voltage control device for gradually decreasing the voltage value.

3. A micropump, including:

a piston; and

a comb actuator comb for generating an electrostatic force after receiving a voltage, so as to actuate the piston to make a first displacement, which causes a fluid to enter into a cavity, wherein the voltage has a voltage value for determining the volume of the fluid entering into the cavity, and wherein as the voltage value of the voltage gradually decreases, the electrostatic forces also decreases, allowing the piston to gradually make a second displacement in a direction opposite to the first displacement driven by a spring, thus outputting the fluid from the cavity.

4. A micropump system of claim 3, further including a voltage control device for changing the voltage value, so as to change the volume of the fluid entering into the cavity.

5. A micropump system of claim 3, wherein the cavity is a cavity with no valve.

6. A micropump system of claim 3, wherein the fluid enters the cavity through an inlet.

7. A micropump system of claim 6, wherein the fluid exits the cavity through an outlet.

8. A micropump system of claim 7, wherein there is a specific angle between the entering direction of the inlet and the exit direction of the outlet, such that the flowing direction of the fluid is controlled.

9. An actuating method of a micropump, including:

applying a voltage to a comb actuator to generate an electrostatic force for actuating a piston, allowing the piston to make a first displacement for causing a fluid to flow into a cavity, wherein the voltage has a voltage value for determining the volume of the fluid entering into the cavity; and

gradually decreasing the voltage to reduce the electrostatic forces, allowing the piston to gradually make a second displacement in a direction opposite to the first displacement driven by a spring, thus outputting the fluid from the cavity

10. An actuating method of a micropump of claim 9, further including a voltage control device for changing the voltage value, so as to change the volume of the fluid entering into the cavity.

11. An actuating method of a micropump of claim 9, wherein the cavity is a cavity with no valve.

12. An actuating method of a micropump of claim 9, wherein the fluid enters the cavity through an inlet.

13. An actuating method of a micropump of claim 12, wherein the fluid exits the cavity through an outlet.

14. An actuating method of a micropump of claim 3, wherein there is a specific angle between the entering direction of the inlet and the exit direction of the outlet, such that the flowing direction of the fluid is controlled.