U.S. patent application number 10/728831 was filed with the patent office on 2005-03-31 for micro pump using ferrofluid or magneto-rheological fluid.
Invention is credited to Liu, Min-Sheng, Lu, Ming-Chang, Wang, Chi-Chuan.
Application Number | 20050069424 10/728831 |
Document ID | / |
Family ID | 34374588 |
Filed Date | 2005-03-31 |
United States Patent
Application |
20050069424 |
Kind Code |
A1 |
Lu, Ming-Chang ; et
al. |
March 31, 2005 |
Micro pump using ferrofluid or magneto-rheological fluid
Abstract
A micro pump using a ferro-fluid/magneto-rheological fluid to
drive a working fluid is proposed. The micro pump has a body with
an accommodating space and an opening that communicates with the
accommodating space. A ferro-fluid/magneto-rheological fluid and a
magnetic field generating unit are disposed on the body. As the
ferro-fluid/magneto-rheological fluid is attracted to the magnetic
field after being magnetized, the ferro-fluid/magneto-rheological
fluid is deformed or shifted to drive the working fluid, so as to
control the working fluid to flow in and out of the accommodating
space. Accordingly, the pump is improved for its efficiency and
precision to control the flow while the back flow of the working
fluid is prevented.
Inventors: |
Lu, Ming-Chang; (Hsinchu,
TW) ; Wang, Chi-Chuan; (Hsinchu, TW) ; Liu,
Min-Sheng; (Hsinchu, TW) |
Correspondence
Address: |
RABIN & BERDO, P.C.
Suite 500
1101 14th Street, N.W.
Washington
DC
20005
US
|
Family ID: |
34374588 |
Appl. No.: |
10/728831 |
Filed: |
December 8, 2003 |
Current U.S.
Class: |
417/322 |
Current CPC
Class: |
F04B 19/006 20130101;
F04B 7/003 20130101; F04B 7/0038 20130101; F04B 53/1077 20130101;
F04B 43/043 20130101 |
Class at
Publication: |
417/322 |
International
Class: |
F04B 017/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 26, 2003 |
TW |
092126595 |
Claims
What is claimed is:
1. A micro pump using ferro-fluid/magneto-rheological fluid for
driving a working fluid, the micro pump comprising at least a micro
pump component, wherein the micro pump component comprising: a body
having an accommodating space and an opening for communicating with
to the accommodating space; a membrane formed in the accommodating
space for separating the accommodating space into a first space and
a second space, in such a way that the opening communicates the
second space; a ferro-fluid/magneto-rheological fluid filled in the
first space; and a magnetic field generating unit for applying a
magnetic field to the accommodating space, so that to deform the
membrane via the ferro-fluid/magneto-rheological fluid to drive the
working fluid to flow in/out of the opening.
2. The micro pump of claim 1, wherein the membrane is a
polydimethylisiloxane (PDMS) membrane.
3. The micro pump of claim 1, wherein the body comprising a first
body and a second body so that the accommodating space is formed
from recessed portions of the first and second body.
4. The micro pump of claim 1, wherein two openings are formed on
the body to serve as an entrance and an exit for the working fluid
to flow in and out of the second space.
5. The micro pump of claim 4, wherein the opening includes a
diffuser and a nozzle.
6. The micro pump of claim 4, further comprising an opening control
device formed on the opening to open the exit and close the
entrance when the working fluid is required to flow out of the
opening, and to open the entrance and close the exit when the
working fluid is required to flow in the opening.
7. The micro pump of claim 6, wherein the opening control device
comprising a ferro-fluid/magneto-rheological fluid whose position
shift is driven by a magnetic field.
8. The micro pump of claim 1, wherein the body is a silicon
substrate.
9. The micro pump of claim 1, wherein the magnetic field generating
unit is installed in the body.
10. The micro pump of claim 1, wherein the magnetic field
generating unit is a electromagnet switch.
11. A micro pump using ferro-fluid/magneto-rheological fluid is
applicable to driving a working fluid, the micro pump having at
least a micro pump component and each of the micro pump component
comprising: a body having at least an accommodating space and an
opening communicates with the accommodating space; at least two
ferro-fluid/magneto-rheological fluid components disposed on two
corresponding sides of the accommodating space; and a magnetic
field generating unit for driving the at least two
ferro-fluid/magneto-rheological fluid components, so that the
ferro-fluid/magneto-rheological fluid components are shifted
constantly to drive the working fluid flowing in/out of the
opening.
12. The micro pump of claim 11, wherein the
ferro-fluid/magneto-rheologica- l fluid component is a
ferro-fluid/magneto-rheological fluid immiscible to the working
fluid.
13. The micro pump of claim 11, wherein the
ferro-fluid/magneto-rheologica- l fluid component is a
ferro-fluid/magneto-rheological fluid encapsulated by the
membrane.
14. The micro pump of claim 11, wherein the membrane is a
polydimethylisiloxane (PDMS) membrane.
15. The micro pump of claim 11, wherein two openings are formed on
the body to serve as an entrance and an exit for the working fluid
to flow in and out of the second space.
16. The micro pump of claim 15, wherein the opening includes a
diffuser and a nozzle.
17. The micro pump of claim 15, further comprising an opening
control device formed on the opening to open the exit and close the
entrance when the working fluid is required to flow out of the
opening, and to open the entrance and close the exit when the
working fluid is required to flow in the opening.
18. The micro pump of claim 17, wherein the opening control device
comprising a ferro-fluid/magneto-rheological fluid whose position
shift is driven by a magnetic field.
19. The micro pump of claim 11, wherein the body is a silicon
substrate.
20. The micro pump of claim 11, wherein the body further comprising
a top lid such that the magnetic field generating unit is formed on
the top lid.
21. The micro pump of claim 11, wherein the magnetic field
generating unit is a movable magnet capable of driving position
shifting of the ferro-fluid/magneto-rheological fluid.
22. The micro pump of claim 11, wherein magnetic field generating
unit is a sequential actuating electromagnet arranged in an array.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The invention relates to a micro pump using ferrofluid or
magneto-rheological fluid, and more particularly, to a micro pump
that improves flow and pump efficiency.
[0003] 2. Description of the Related Art
[0004] The micro fluid control device fabricated by
microelectromechanical system (MEMS) technology is characterized by
having a small size, precise flow control, and fast reaction time.
As the micro fluid control device can be integrated with the
conventional micro sensor on the same system for a feedback
control, a large batch of the micro fluid control devices may be
manufactured. Therefore, the micro fluid device has become one
device that is worth of researches and widely implemented in the
industry.
[0005] For a micro pump component in the micro fluid control
device, its related technology has been developed to a matured
stage, so the micro pump component has been applied to different
fields, such as chemical analysis, biomedical system, micro cooling
system, and so on. Typically, a membrane type micro pump 80 shown
in FIG. 11 is adopted. The micro pump 80 has two membrane type
valves 81 that serve as an entrance 82 and an exit 83 respectively
for an external working fluid to enter or exit the micro pump 80,
while flow direction control for the working fluid is also provided
by the valves 81. However, after a long-term use, the valves and
moving parts are gradually worn out to lose their reliability, even
causing fatigue at valve connector ends in some cases. Such valve
design may eventually lead to loss of the fluid pressure, which in
turn reduces flow to be driven by the pump or causes contamination
due to back flow of the working fluid.
[0006] Then, a valve-less micro pump 85 that uses a piezoelectric
material as a driving source is proposed as shown in FIGS. 12A and
12B. A piezoelectric piece 86 made of piezoelectric material serves
as a driving source for the working fluid to cause deformation of
the piezoelectric piece 86 via a voltage control. As a result, the
external working fluid is driven to flow into the micro pump 85 as
shown in FIG. 12A or flow out of the micro pump 85 as shown in FIG.
12B. Although the design is free from problems associated with the
above mentioned valves and moving parts, deformation level of the
piezoelectric piece 86 is limited by its material characteristics,
so the output flow is consequently limited. Thus, it is difficult
to satisfy the commercial need with the valve-less micro pump 85.
Also, back flow may occur to reduce efficiency in driving the
working fluid and cause contamination of the working fluid when the
micro pump of the above design is operated.
[0007] The later design utilizes a ferromagnetic-fluid to drive the
working fluid in the micro pump so as to achieve a higher driving
efficiency and flow. Referring to FIG. 13, the design involves a
round closed tubing 90, which is filled with the working fluid 91
and a section of ferro-magnetic fluid 92. An entrance 93 and an
exit 94 are formed respectively on the tubing 90 to open to
outside, and a fixed magnet 95 is disposed in between the entrance
93 and the exit 94. A moving magnet 96 is formed on the inner side
of the tubing 90 to move along the tubing 90, so that
ferro-magnetic fluid 92 is driven by the moving magnet 96 to move
within the tubing 90. A valve door is formed at either the entrance
93 or exit 94 of the tubing 90 via the fixed magnet 95. The valve
door is operated as illustrated to drive the working fluid 91
entering from the entrance 93 to discharge out of the exit 94, so
as to complete a pump cycle. However, despite of efficiency in
terms of driving the working fluid, serious contamination problem
caused by mixing the working fluid 91 and the ferro-magnetic fluid
92 is not taken into account in designing this micro pump. When the
micro pump is applicable to fields, such as chemical analysis and
biomedical system, it is often required that the working fluid to
be driven by the pump has a high purity. While the micro pump of
such design is operated as such, the working fluid 91 to be
discharged clearly does not fulfill such requirement, and the
contamination problem gets worse as the operation time gets longer,
making such design unpractical in terms of fulfilling the
industrial demand.
[0008] Therefore, it is an objective for this field of art to
develop a micro pump that improves its driving flow and controls
precision of flow to prevent the back flow of the working fluid, so
as to prevent contamination of the working fluid.
SUMMARY OF THE INVENTION
[0009] The primary objective of the present invention is to provide
a micro pump using ferrofluid or megneto-rheological fluid, which
micro pump improves flow and pump efficiency.
[0010] Another objective of the present invention is to provide a
micro pump using ferrofluid or megneto-rheological fluid, which
micro pump precisely controls flow.
[0011] One other objective of the present invention is to provide a
micro pump using ferrofluid or megneto-rheological fluid, which
micro pump prevents back flow of a working fluid.
[0012] A further objective of the present invention is to provide a
micro pump using ferrofluid or megneto-rheological fluid, which
micro pump has a high reaction ferquency.
[0013] And yet another objective of the present invention is to
provide a micro pump using ferrofluid or megneto-rheological fluid
without contaminating the working fluid.
[0014] And yet one other objective of the present invention is to
provide a micro pump using ferrofluid or megneto-rheological fluid
without wearing out moving parts of the pump.
[0015] And yet further objective of the present invention is to
provide a micro pump using ferrofluid or megneto-rheological fluid,
which micro pump reduces loss of fluid pressure.
[0016] And still another objective of the present invention is to
provide a micro pump using ferrofluid or megneto-rheological fluid
without limiting its appearance.
[0017] In accordance with the above and other objectives, the
present invention proposes the micro pump that uses ferrofluid or
megneto-rheological fluid to drive the working fluid. The micro
pump has at least a micro pump component, each component comprises
a body having an accommodating space formed therein and an opening
that communicates with the accommodating space. A membrane is
formed in the accommodating space to separate a first space and a
second space in such a way that the second space communicates with
the opening. The second space is filled with a working fluid. The
micro pump component also comprises a
ferro-fluid/magneto-rheological fluid that fills the first space
and a magnetic field generating component that applies magnetic
field to the accommodating space. As a result, the membrane is
deformed constantly via the ferro-fluid/magneto-rheological fluid
to drive the working fluid flowing through the opening.
[0018] The present invention proposes another micro pump component
that comprises a body having an accommodating space formed therein
and at least an opening that communicates with the accommodating
space. The accommodating space is filled with the working fluid.
The micro pump component further comprises at least two
ferro-fluid/magneto-rheological fluid components located
respectively on two corresponding sides of the accommodating space,
and magnetic filed generating component for driving the at least
two ferro-fluid/magneto-rheological fluid components. Consequently,
a constant shifting is generated for the
ferro-fluid/magneto-rheological fluid components in order to drive
the working fluid flowing through the opening.
[0019] Each of the ferro-fluid/magneto-rheological fluid components
is a ferro-fluid/magneto-rheological fluid immiscible to the
working fluid or a ferro-fluid/magneto-rheological fluid molded by
encapsulating in the membrane. The ferro-fluid/magneto-rheological
fluid includes iron or ferroxide particles, wherein the particles
are attracted to each other when they are magnetized by an external
magnetic field to align in the same direction, so that the
ferro-fluid/magneto-rheological fluid is transformed within a few
seconds into a magnetic solid. As the magnetic field is removed,
the magnetic particles return to particle bombardments to evenly
distribute in the ferro-fluid/magneto-rheological fluid. As a
result, the solidified ferro-fluid/magneto-rheological fluid is
quickly changed to a liquid form.
[0020] As the ferro-fluid/magneto-rheological fluid is magnetized
by the magnetic field to transform into the magnetic solid, the
magnetic solid is attracted by the magnetic field to produce
deformation and position shifting, such that the working fluid can
be driven by the deformation and position shifting to flow in/out
of the body of the micro pump to achieve pump function.
[0021] There are two openings formed on the body serving
respectively as entrance and exit for the working fluid to flow
in/out of the accommodating space, and the two openings are formed
as a diffuser and a nozzle. Meanwhile, an opening control device is
further formed on the opening for opening the exit and closing the
entrance when the working fluid is required to flow out via the
exit. Similarly, the opening control device communicates the
entrance and closes the exit when the working fluid is required to
flow in via the entrance. The opening control device further
comprises another ferro-fluid/magneto-rheological fluid driven by
the magnetic field to shift in such a way as to precisely control
closing of the entrance and exit. Therefore, back flow of the
working fluid is prevented, while efficiency in driving the working
fluid is also improved.
[0022] According to the micro pump of the present invention,
characteristics of the ferro-fluid/magneto-rheological fluid where
the ferro-fluid/magneto-rheological fluid is attracted by the
magnetic field after the fluid is magnetized and solidified may be
adopted. With the ferro-fluid/magneto-rheological fluid serving as
a source for driving the working fluid, input/output of the working
fluid may be controlled via deformation and position shifting of
the ferro-fluid/magneto-rheological fluid, and both pump efficiency
and output flow of the micro pump are significantly improved.
Meanwhile, the flow may be precisely controlled via opening control
device made of ferro-fluid/magneto-rheological fluid to prevent
occurrence of the back flow.
[0023] To provide a further understanding of the invention, the
following detailed description illustrates embodiments and examples
of the invention, it is to be understood that this detailed
description is being provided only for illustration of the
invention and not as limiting the scope of this invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The drawings included herein provide a further understanding
of the invention. A brief introduction of the drawings is as
follows:
[0025] FIG. 1 is a cross-sectional view of a micro pump according
to the first embodiment of the present invention;
[0026] FIG. 2A is a schematic diagram illustrating the
magneto-rheological fluid component without influence of the
magnetic field;
[0027] FIG. 2B is a schematic diagram illustrating a solidified
magneto-rheological fluid after being magnetized by a magnetic
field;
[0028] FIG. 3A is a cross-sectional view illustrating operation of
the first embodiment shown in FIG. 1 in its pump mode;
[0029] FIG. 3B is a cross-sectional view illustrating operation of
the first embodiment shown in FIG. 1 in its supply mode;
[0030] FIG. 4 is a cross-sectional view illustrating a pump module
assembled by the first embodiment shown in FIG. 1;
[0031] FIG. 5A is an elevation view illustrating the micro pump
without a top lid disposed thereon according to the second
embodiment of the present invention;
[0032] FIG. 5B is an elevation view illustrating the top lid of the
micro pump according to the second embodiment of the present
invention;
[0033] FIG. 6A is a schematic diagram illustrating shifting of two
movable magnets shown in FIG. 5B;
[0034] FIG. 6B is a schematic diagram illustrating shifting of two
ferro-fluid/magneto-rheological fluid components shown in FIG.
5A;
[0035] FIG. 7 is an elevation view illustrating another magnetic
field generating component on the top lid shown in FIG. 5B;
[0036] FIG. 8 is a cross-sectional view illustrating a pump module
after the second embodiment shown in FIG. 5A is assembled;
[0037] FIG. 9A is a cross-sectional view illustrating operation of
the opening control device in its suppky mode according to the
embodiment shown in FIG. 8;
[0038] FIG. 9B is a cross-sectional view illustrating operation of
the opening control device in its pump mode according to the
embodiment shown in FIG. 8;
[0039] FIG. 10 is a schematic diagram illustrating operations of
the embodiment shown in both FIGS. 9A and 9B when the fluid
switching function is installed;
[0040] FIG. 11 is a cross-sectional view illustrating thin-film
type micro pump;
[0041] FIGS. 12A and 12B are cross-sectional views illustrating a
conventional piezoelectric type micro pump; and
[0042] FIG. 13 is a schematic diagram illustrating operation of a
conventional ferro-fluid/magneto-rheological fluid driven micro
pump.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0043] According to the present invention, a micro pump using
ferro-fluid/magneto-rheological fluid is fabricated in the
microelectromechanical (MEM) process and comprises a plurality of
micro pump components assembled together. FIG. 1 is a
cross-sectional view of a micro pump according to the first
embodiment of the present invention. Referring to FIG. 1, a silicon
substrate body comprising a first body 10 and a second body 15 is
provided such that an accommodating space 20 within the silicon
substrate body is formed from recess portions of the first and
second bodies 10 and 15. Two openings are formed at the junction
gaps between the two bodies 10 and 15 to serve as an entrance 21
and an exit 22 for a working fluid on two corresponding sides of
the accommodating space 20. A polydimethylisiloxane (PDMS) membrane
30 is formed in the accommodating space and located above the
entrance 21 and the exit 22 to separate the accommodating space 20
into a first space 25 and a second space 26. As a result, the
entrance 21 and the exit 22 communicates the second space 26 to
outside, and the second space 26 serves as a channel through which
the working fluid flows in/out of the micro pump 1.
[0044] The first space 25 is filled with a
ferro-fluid/magneto-rheological fluid 40. The
ferro-fluid/magneto-rheological fluid 40 may be nano
particles/micro particles consisting of iron or oxidized iron, so
as to transform instantly the fluid from a liquid form to a solid
form when the magnetic particles in the fluid are magnetized by the
magnetic field. Also, a magnetic field generating unit, such as an
electromagnet switch 50 is disposed in the second body. The
electromagnet switch 50 applies a forward and reverse magnetic
field to the accommodating space 20 constantly using a
positive/negative voltage based on a predetermined frequency.
[0045] The PDMS membrane 30 described above may be selected from
other silicone materials. For example, the membrane may include a
polymethylphenylsiloxane (PMPS) membrane, a polydiphenylsiloxane
(PDPS) membrane or other co-polymers, such as
poly(dimethylisiloxane)-co-poly(di- phenylsiloxane). Other polymer
materials, including polypropylene (PP) and polyethylene (PE) may
also be used to fabricate the membrane 30 having a thickness of
about 25 .mu.m with excellent retractility. The present embodiment
is not limited to generating the forward/reverse magnetic field
using the electromagnet switch 50, other magnetic field generating
units that generate the magnetic field and drive the
ferro-fluid/magneto-rheological fluid 40 based on the
pre-determined frequency may similarly be disposed in the second
body 15. The entrance 21 and exit 22 formed at junction gaps
between the first and second bodies 10 and 15 may be designed
according to the MEMS process as a diffuser 23 and a nozzle 24,
respectively, to replace valves of the conventional micro pump. An
opening control device (not shown) may be further formed on the
diffuser 23 and the nozzle 24 to match operations of the
electromagnet switch 50 in opening or closing the entrance 21 or
exit 22 at appropriate time. As a result, the highest fluid
transmission efficiency is achieved and back flow of the working
fluid is prevented. The design and operation of the micro pump are
described in detail below.
[0046] The micro pump described in the first embodiment uses the
ferro-fluid/magneto-rheological fluid 40 in the first space 25 as a
driving source to drive the working fluid to input in the second
space 26 or output from the second space 26. The operation process
begins by switching on the electromagnet switch 50 to apply
forward/reverse magnetic field to the accommodating space 20 of the
body constantly. The ferro-fluid/magneto-rheological fluid 40 in
the first space 25 is magnetized constantly by magnetic fields from
different directions. This causes particles in the
ferro-fluid/magneto-rheological fluid 40 to align in the same
magnetized direction under attraction of the magnetic fields,
resulting instant solidification of the
ferro-fluid/magneto-rheological fluid 40 as shown in FIG. 2B.
During de-magnetization, the particles are bombarded by the
ferro-fluid/magneto-rheological fluid molecules to move in brownian
motion, so as to evenly distribute in the form of liquid as shown
in FIG. 2A. As the ferro-fluid/magneto-rheological fluid 40 is
magnetized to form the solid, the magnetic solid 40 is attracted by
magnetism of the electromagnet switch 50 to compress the PDMS
membrane 30, causing deformation of the PDMS membrane 30. This
further leads to compression for the second space 26 as shown in
FIG. 3A, so that output of the working fluid from the second space
26 is greater than input of the working fluid to the second space
26. The micro pump then performs a pump mode operation. On the
other hand, when the electromagnet switch 50 is subjected to a
lower voltage by a voltage function designed as sine wave to apply
a smaller magnetic field to the accommodating space 20, the
attraction applied to the magnetic solid 40 is smaller than a
restoring force of the PDMS membrane 30, so that the PDMS membrane
30 is deformed and restored to its original position in opposite
direction to compress the first space 25, while the second space 26
that is filled with the working fluid is enlarged as shown in FIG.
3B. Meanwhile, input of the working fluid to the second space 26 is
greater than output of the working fluid from the second space 26.
The micro pump then performs the supply mode operation to complete
an entire pump cycle and achieve efficiency in driving the working
fluid.
[0047] In the micro pump of the present embodiment, the
electromagnet switch 50 has a switching frequency of 1000 Hz and
above, while the phase change for the
ferro-fluid/magneto-rheological fluid 40 is completed within
microseconds. Therefore, the PDMS membrane 30 may be able to
vibrate reciprocally at the frequency of 1000 Hz, and the working
fluid may be driven accordingly to achieve a driving frequency of
1000 Hz and above.
[0048] Since the PDMS membrane 30 is highly retractable, the
electromagnet switch 50, besides plays a role in applying the
forward/reverse magnetic field, may alternate between actions of
applying magnetic field and removing magnetic field to achieve the
same reciprocating vibration of the PDMS membrane 30. At the
instant when the magnetic field is removed, the magnetic solid 40
is changed into the ferro-fluid/magneto-rheological fluid. The
fluid is no longer attracted by the electromagnet switch 50, so the
PDMS membrane 30 is quickly deformed to retract, achieving the same
pump cycle as shown in both FIGS. 3A and 3B.
[0049] Summarizing from the above, it is understood that the
driving source in the first embodiment is the
ferro-fluid/magneto-rheological fluid 40 that is controlled by
additional magnetic fields. And frequencies for the magnetic field
variation and phase change of the ferro-fluid/magneto-rheological
fluid are quite high. Therefore, the PDMS membrane 30 may have a
significantly high deformation level and deformation frequency to
drive a higher flow than the micro pump in the prior art does and
to precisely regulate the flow via the magnetic field. Accordingly,
the present embodiment may be implemented in the micro cooling/air
conditioning system that requires a large flow or a biomedical
system that requires a precise flow. In the present embodiment,
moving parts and valves associated with the conventional design may
be omitted to avoid wearing of the extra components or loss of
fluid pressure. With the opening control device, the closure of the
entrance and exit is controlled to prevent contamination due to
back flow of the working fluid. And the entire micro pump structure
is not limited by its appearance as it has the
ferro-fluid/magneto-rheological fluid in liquid form.
[0050] The present embodiment is described with a single micro pump
component 1 as an example. However, a plurality of micro pump
components 1 may also be assembled as shown in FIG. 4 in the micro
pump using the ferro-fluid/magneto-rheological fluid to increase
the entire flow to be driven as well as to extend applicable fields
of the present invention.
[0051] FIG. 5A is an elevation view illustrating the micro pump
without a top lid disposed thereon according to the second
embodiment of the present invention. The second embodiment is
described with a single micro pump component 2 as an example. FIG.
5B illustrates a top lid 55 of the micro pump 2 according to the
second embodiment of the present invention. Referring to FIG. 5A,
the micro pump comprises a silicon substrate body 60 having an
accommodating space 65, and an entrance 61 and an exit 62 are
formed respectively on both sides of the body. The entrance 61 and
the exit 62 are designed as a diffuser 63 and a nozzle 64
respectively to open to the accommodating space 65 and serve as
openings for the working fluid to flow in and out of the
accommodating space 65. So, the accommodating space 65 becomes a
channel for the working fluid. Each of the two corresponding sides
of the accommodating space 65 is filled with a
ferro-fluid/magneto-rheological fluid unit 70 so that both the
ferro-fluid/magneto-rheological fluid unit 70 and the working fluid
are located in the accommodating space 65.
[0052] The ferro-fluid/magneto-rheological fluid unit 70 is a
ferro-fluid/magneto-rheological fluid immiscible to the working
fluid or a ferro-fluid/magneto-rheological fluid that is molded by
encapsulating in the PDMS membrane. Since contamination of the
working fluid reduces the operating efficiency of the pump. If it
is possible for the ferro-fluid/magneto-rheological fluid to be
miscible to the working fluid, the ferro-fluid/magneto-rheological
fluid needs to be encapsulated and isolated by the PMDS membrane to
prevent the ferro-fluid/magneto-rheo- logical fluid from
contaminating the working fluid. Similarly, the
ferro-fluid/magneto-rheological fluid has nano particles such as
iron or iron oxide described in the first embodiment. And the PDMS
membrane may also be substituted with other materials that produce
the equivalent effect.
[0053] The top lid 55 shown in FIG. 5B is disposed on the body 60
illustrated in FIG. 5A in such a way that the top lid 55 seals up
the accommodating space 65. Two movable magnets 56 are disposed on
the top lid 55 to correspond to position of the
ferro-fluid/magneto-rheological fluid unit 70 in the accommodating
space 65, so that the ferro-fluid/magneto-rheological fluid unit 70
is magnetized by the movable magnets 56 to form a magnetic solid.
And the magnetic solid is driven to shift position when the movable
magnets 56 move.
[0054] Therefore, the movable magnets 56 on the top lid 55 serve as
a driving source for the micro pump of the second embodiment. As
shown in FIGS. 6A and 6B, the two movable magnets 56 move to the
center of the top lid 55 to drive two corresponding
ferro-fluid/magneto-rheological fluid units 70 to shift until they
approach to each other. The working fluid in the accommodating
space is then squeezed by the two ferro-fluid/magneto-rheological
fluid units 70, so that output of the working fluid via the exit 62
is greater than input of the working fluid via the entrance 61, and
the micro pump performs a pump mode operation. On the other hand,
when the movable magnets 56 are driven to repel from each other
until they return to two corresponding sides of the top lid 55, the
input of the working fluid via the entrance 61 is greater than the
output of the working fluid via the exit 62 due to a pressure drop
in the accommodating space 65. And the micro pump performs a supply
mode operation to complete one pump cycle.
[0055] Thus, if the frequency of reciprocating movement for the
movable magnets 26 is adjusted to 1000 Hz and above, the frequency
of reciprocal shifting for the ferro-fluid/magneto-rheological
fluid units 70 may also reach 1000 Hz to drive the working fluid,
achieving a driving frequency of 1000 Hz and above.
[0056] The top lid 55 in this embodiment is not limited to the
design shown in FIG. 5B, the entire surface of the top lid 55 may
also be disposed serially with rows of electromagnets 57 as
illustrated in FIG. 7. The magnetic field of the electromagnets 57
may be initiated in sequence from two sides of the top lid 55 to
its center as indicated by arrows in the diagram, so as to achieve
the equivalent magnetic field shifting effect produced by the
movable magnets 56 in FIG. 5B. As a result, the two corresponding
ferro-fluid/magneto-rheological fluid units 70 shift in the
accommodating space 65 until they approach each other, in order to
produce a satisfactory fluid driving effect.
[0057] The micro pump components 2 in the second embodiment can be
assembled to each other as shown in FIG. 8 (the top lid is not
shown). A greater flow of the working fluid is then output, making
it feasible to implement the micro pump of this embodiment in the
micro cooling/air conditioning system that requires a large flow.
And an opening control device may be disposed on the diffuser 63
and nozzle 64 as well as the entrance 61 and exit 62 shown in both
FIGS. 9A and 9B. The opening control device in this case is the
same as the opening control device described in the first
embodiment and includes a plurality of
ferro-fluid/magneto-rheological fluids 71a and 71b driven by the
magnetic field to shift via magnetic field variation within a first
channel 72 on an entrance side and a second channel 73 on an exit
side. As the opening control device and the
ferro-fluid/magneto-rheological fluid units 70 in the accommodating
space 65 are integrated to shift synchronously by the magnetic
field, satisfactory effects in terms of ideal flow and flow
direction control are achieved. For example, when the micro pump is
operated at the supply mode as shown in FIG. 9A, the
ferro-fluid/magneto-rheological fluid units 70 are arranged on two
sides. The ferro-fluid/magneto-rheological fluid unit 71b in the
second channel on the exit side then shifts to seal up the exit 62
of the accommodating space, so that the working fluid can flow from
the entrance 61 on the entrance side into the accommodating space
65. On the other hand, when the micro pump is operated at the pump
mode as shown in FIG. 9B, the ferro-fluid/magneto-rheological fluid
units 70 are driven by the magnetic field on the top lid 55 to
shift until they approach each other. As a result, the working
fluid in the accommodating space 65 is squeezed while the
ferro-fluid/magneto-rheological fluid unit 71a in the first channel
72 on the entrance side shifts to seal up the entrance 61 of the
accommodating space 65. The working fluid in the accommodating
space 65 then flows out only from the exit 62 on the exit side.
Thus, the flow direction is precisely controlled without causing
back flow of the working fluid as well as contamination for the
working fluid associated with use of the conventional micro
pump.
[0058] Referring to FIG. 10, an embodiment of the micro pump is
illustrated with a fluid switching function is further installed on
the opening control device according to FIGS. 9A and 9B, so as to
more precisely control input or output of the working fluid. In the
operation mode shown in the diagram, the working fluid is
discharged out via shifting of the ferro-fluid/magneto-rheological
fluid unit 70. Then, with the fluid switching function, the
magnetic field control is operated to cause shifting of the
ferro-fluid/magneto-rheological fluid unit 7lb in the second
channel 73. Consequently, the exit 62 is open to allow the desired
working fluid to output from the exit 62 of the micro pump, so as
to fulfill requirements for both a large flow and precise flow
control. Therefore, the present invention is feasible to implement
in the biomedical system that requires precise flow control.
[0059] Summarizing from the second embodiment above, a greater flow
is driven using the external magnetic field and position shift of
the ferro-fluid/magneto-rheological fluid unit 70, regardless of
whether the micro pump is made of a single micro pump component 2
or a plurality of micro pump components 2. Furthermore, the flow
can be precisely controlled via the magnetic field, while the
moving parts and valves associated with the conventional micro pump
structure may be omitted to prevent wearing out of extra components
or loss of fluid pressure. And with the opening control device,
closure of the entrance 61 and exit 62 may be controlled to prevent
back flow of the working fluid that causes contamination. The
entire micro pump structure is also not limited by its appearance
since the ferro-fluid/magneto-rheological fluid in the
accommodating space 65 is in liquid form.
[0060] According to the present invention, a micro pump using the
ferro-fluid/magneto-rheological fluid is proposed. The micro pump
controls deformation and position shifting of the
ferro-fluid/magneto-rhe- ological fluid precisely and quickly using
the additional magnetic field to drive the working fluid, so that
drawbacks associated with using the conventional micro pump are
resolved.
[0061] It should be apparent to those skilled in the art that the
above description is only illustrative of specific embodiments and
examples of the invention. The invention should therefore cover
various modifications and variations made to the herein-described
structure and operations of the invention, provided they fall
within the scope of the invention as defined in the following
appended claims.
* * * * *