US20070122299A1

US20070122299A1 - Valveless micro impedance pump

Info

Publication number: US20070122299A1
Application number: US11/288,186
Authority: US
Inventors: Chih-Yung Wen; Chiang-Ho Cheng; Chia-Nan Chien
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-11-29
Filing date: 2005-11-29
Publication date: 2007-05-31

Abstract

A valveless micro impedance pump including a bottom layer, a middle layer, a top layer and a piezoelectric element. The middle layer and the top layer are sealed to form the water inlets/outlets, flow way, upper and lower vibration membranes and boss of the micropump. The piezoelectric element is fixed on the boss and the fixing seat. By means of the electric field effect, the upper and lower vibration membranes are pushed by the piezoelectric element through the boss. The medium within the flow way is squeezed to flow toward the water inlets/outlets on two sides. The upper and lower vibration membranes have different structures. Also, the hardness of the fixing seat is different from the hardness of the bottom layer. This leads to difference in impedance. Therefore, the wave of the medium can be transmitted.

Description

BACKGROUND OF THE INVENTION

The present invention is related to a valveless micro impedance pump in which the difference between impedances of materials results in difference between the impedances of the walls of the flow way for transmitting a medium.
The conventional micro-fluid elements are mainly developed and applied to control, detection, reaction and analysis of micro-fluid. The key elements include micropumps, microvalves, micro-flow ways, micromixers, etc. These elements can be integrated into intelligent micro-fluid chips with different functions. The intelligent micro-fluid chips are applicable to biotechnology, portable physiologic monitor, environmental analyzer, precision fluid control, fuel battery engineering, high-resolution nozzle, micro-power system, etc. The micropump is one of the most important key elements.
The micropumps can be mainly divided into valve-equipped type and valveless type. With respect to valveless micropumps, they can be powered by piezoelectric measure, pneumatic measure, static measure, profile-memorizing alloy, thermopneumatic measure, ultrasonic measure and bimetal.
FIG. 8 is a sectional view of a typical piezoelectric valveless micropump 6. FIG. 9 is a sectional view taken along line B-B of FIG. 8. The piezoelectric valveless micropump 6 is composed of a bottom layer 61, a top layer 62, a piezoelectric element 63 and two micro-flow ducts 64. The piezoelectric valveless micropump 6 is operated in such a manner that a drive voltage is applied to the piezoelectric element 63. The piezoelectric element 63 works to push a vibration membrane 621. The vibration membrane 621 is deformed to cause change of the capacity of a middle flow way 65. This leads to change of pressure. The water comes in from a water inlet 66 and flows through an expanded flow way 67 and the middle flow way 65. The water then flows through another expanded flow way 68 to a water outlet 69. The change of the capacity of the middle flow way 65 results in a pressure difference between the water inlet 66 and water outlet 69. Therefore, the net flow of the water outlet 69 is larger than the net flow of the water inlet 66. Accordingly, the water will flow from the water inlet 66 to the water outlet 69.
The conventional piezoelectric valveless micropump is designed with a complicated expanded flow way. This increases the cost of the piezoelectric valveless micropump. In addition, the liquid can only one-way flow. This limits the application of the piezoelectric valveless micropump.

SUMMARY OF THE INVENTION

It is therefore a primary object of the present invention to provide a valveless micro impedance pump in which the materials are different in structure or hardness to lead to a difference between the impedances of the materials. Accordingly, the walls of the flow way have different impedances. Therefore, the medium within the flow way are waved along with the vibration membranes and thus transmitted to the water inlets/outlets.
According to the above object, the valveless micro impedance pump of the present invention includes:
a bottom layer formed with an opening;
a middle layer overlaid on the bottom layer, the middle layer being formed with an elongated recess in a position corresponding to the position of the opening of the bottom layer, the recess being slightly larger than a width of the opening and serving as a flow way, a bottom area of the middle layer between the flow way and the bottom layer being defined as a lower vibration membrane;
a top layer overlaid on the middle layer, the top layer having a fixing seat, a sink being formed on a nearly central portion of the fixing seat, a boss being disposed in the sink, a first water inlet/outlet being formed between left side of the sink and a left end of the top layer, a second water inlet/outlet being formed between right side of the sink and a right end of the top layer, the water inlets/outlets communicating with the flow way, a bottom area of the sink being defined as an upper vibration membrane; and
a piezoelectric element, a bottom face of the piezoelectric element being lengthwise fixed on top end of the boss and top face of the fixing seat.
The present invention can be best understood through the following description and accompanying drawings wherein:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of the valveless micro impedance pump of the present invention;
FIG. 2 is a sectional view taken along line 2-2 of FIG. 1;
FIG. 3 is a perspective sectional view of the valveless micro impedance pump of the present invention;
FIG. 4 is a flow chart of the manufacturing of the bottom layer of the valveless micro impedance pump of the present invention;
FIG. 5 is a flow chart of the manufacturing of the middle layer of the valveless micro impedance pump of the present invention;
FIG. 6 is a flow chart of the manufacturing of the top layer of the valveless micro impedance pump of the present invention;
FIG. 7 is a sectional view of a second embodiment of the valveless micro impedance pump of the present invention;
FIG. 8 is a sectional view of a conventional piezoelectric valveless micropump; and
FIG. 9 is a sectional view taken along line 9-9 of FIG. 8.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Please refer to FIGS. 1 and 2. The valveless micro impedance pump 1 of the present invention includes a thin sheet-like bottom layer 10 formed with a central opening 101.
The valveless micro impedance pump 1 of the present invention further includes a thin sheet-like middle layer 11 overlaid on the bottom layer 10. The middle layer 11 is formed with an elongated recess in a position corresponding to the position of the opening 101 of the bottom layer 10. The recess is slightly larger than the width of the opening 101 and serves as a flow way 113. Amedium (which can be water or other liquid) can flow through the flow way 113. A bottom area of the middle layer 11 between the flow way 113 and the bottom layer 10 is defined as a lower vibration membrane 114.
The valveless micro impedance pump 1 of the present invention further includes a top layer 12 overlaid on the middle layer 11. A bottom face of the top layer 12 serves as the top face of the flow way 113. The top layer 12 has a fixing seat 121. A sink 122 is formed on a nearly central portion of the fixing seat 121. In this embodiment, the sink 122 is aligned with the opening 101 and has a width equal to the width of the opening 101. A boss 123 is disposed on the bottom of the sink 122. In this embodiment, the boss 123 is asymmetrically disposed on the bottom of the sink 122 proximal to lengthwise left side of the sink 122. A first water inlet/outlet 124 is formed between lengthwise left side of the sink 122 and the left end of the top layer 12. A second water inlet/outlet 124 is formed between lengthwise right side of the sink 122 and the right end of the top layer 12. The water inlets/outlets 124 communicate with the flow way 113. A bottom area of the sink 122 is defined as an upper vibration membrane 125.
The valveless micro impedance pump 1 of the present invention further includes a piezoelectric element 2 fixedly bridged over the sink 122 of the fixing seat 121 between two sides thereof. The bottom face of the piezoelectric element 2 nearly attaches to the top end of the boss 123. The piezoelectric element 2 works by way of uni-morph or bi-morph.
Referring to FIG. 3, the piezoelectric element 2 is fixed on the top face of the fixing seat 121 for driving the micropump. The upper vibration membrane connected with the boss 123 is pushed to produce vibration wave. The medium within the flow way 113 is squeezed by the upper and lower vibration membranes 125, 114 to wave to the water inlets/outlets 124 on two sides. The flow way 113 is defined between the upper vibration membrane 125 and the lower vibration membrane 114. The fixing seat 121 and the bottom layer 10 have different structural designs. Therefore, the thickness of the wall of the flow way is varied and the impedance of the upper and lower vibration membranes, 115, 114 is varied. Accordingly, the hardness of the wall of the flow way is varied with sections of the flow way. In addition, the boss 123 is asymmetrically disposed on the bottom of the sink 122 proximal to one side of the fixing seat 121. As a result, when the medium waves to collide a section of the fixing seat 121 more proximal to the boss 123, the wave of the medium will be reflected in reverse direction. The wave is continuously collided and reflected so that the medium is transmitted to the water inlet/outlet 124 distal from the boss 123. By means of changing the driving frequency of the piezoelectric element 2, the flow can be otherwise controlled and the medium can flow in reverse direction.
The bottom layer 10, middle layer 11 and top layer 12 of the present invention are made by means of photolithography in semiconductor manufacturing procedure. The bottom layer 10, middle layer 11 and top layer 12 are mainly made of electrocasting nickel. The manufacturing procedure is described as follows:
FIG. 4 shows the manufacturing flow chart of the bottom layer 10 of the valveless micro impedance pump 1 of the present invention. In step (a) of FIG. 4, a stainless steel plate 21 is prepared. In step (b), a certain thickness of photoresistor 22 is painted on the stainless steel plate 21. In step(c), through exposure, development and washing out photoresistor 22, a desired pattern is left. In step (d), by means of micro-electrocasting technique, the desired structure is electrocast. The material of the structure is nickel. Finally, in step (e), the photoresistor 22 is removed and the structure is demolded to separate from the stainless steel plate 21 and form the bottom layer 10 of the valveless micro impedance pump 1 of the present invention.
FIG. 5 shows the manufacturing flow chart of the middle layer 11 of the valveless micro impedance pump 1 of the present invention. In step (a) of FIG. 5, a stainless steel plate 21 is prepared. In step (b), a layer of nickel is electrocast on the stainless steel plate 21 to form the lower vibration membrane 114. In step (c), a certain thickness of photoresistor 22 is painted on the lower vibration membrane 114. In step (d), through exposure, development and washing out photoresistor 22, a desired pattern is left. In step (e), by means of micro-electrocasting technique, the desired structure is electrocast. The material of the structure is nickel. Finally, in step (f), the photoresistor 22 is removed and the structure is demolded to separate from the stainless steel plate 21 and form the middle layer 11 of the valveless micro impedance pump 1 of the present invention. The middle layer 11 includes the lower vibration membrane 114 and the flow way 113.
FIG. 6 shows the manufacturing flow chart of the top layer 12 of the valveless micro impedance pump 1 of the present invention. In step (a) of FIG. 6, a stainless steel plate 21 is prepared. In step (b), a layer of photoresistor 22 is painted on the stainless steel plate 21. In step (c), through exposure, development and washing out photoresistor 22, a desired pattern is left. In step (d), a layer of nickel is electrocast to form the upper vibration membrane. In step (e) of a secondary photolithography, a certain thickness of photoresistor. 22 is painted on the upper vibration membrane 125. In step (f), through exposure, development and washing out photoresistor 22, a desired pattern is left. In step (g), again by means of micro-electrocasting technique, the fixing seat 121 is electrocast. The material of the fixing seat 121 is nickel. Finally, in step (h), the photoresistor 22 is removed and the structure is demolded to separate from the stainless steel plate 21 and form the top layer 12 of the valveless micro impedance pump 1 of the present invention. The top layer 12 includes the fixing seat 121, the sink 122, the boss 123, the water inlets/outlets 124 and the upper vibration membrane 125.
FIG. 7 shows a second embodiment of the present invention, in which two bosses 123A are disposed in the sink 122A of the top layer 12A. In this embodiment, the bosses 123A are symmetrically arranged. A piezoelectric element 2A is disposed on each boss 123A. The bottom face of the piezoelectric element 2A is lengthwise fixed on top end of the boss 123A and top face of the fixing seat 121A.
According to the above arrangement, by means of the effect of the electric field, the upper and lower vibration membranes 125A, 114A are pushed by the piezoelectric elements through the bosses 123A. The medium within the flow way 113A is squeezed to flow toward the water inlets/outlets 124A on two sides. The upper and lower vibration membranes 125A, 114A have different structures. Also, the hardness of the fixing seat 121A is different from the hardness of the bottom layer 10A. This leads to difference in impedance. Therefore, the wave of the medium can be transmitted.
The above embodiments are only used to illustrate the present invention, not intended to limit the scope thereof. Many modifications of the above embodiments can be made without departing from the spirit of the present invention.

Claims

1. A valveless micro impedance pump comprising:

a bottom layer formed with an opening;

a middle layer overlaid on the bottom layer, the middle layer being formed with an elongated recess in a position corresponding to the position of the opening of the bottom layer, the recess being slightly larger than a width of the opening and serving as a flow way, a bottom area of the middle layer between the flow way and the bottom layer being defined as a lower vibration membrane;

a top layer overlaid on the middle layer, the top layer having a fixing seat, a sink being formed on a nearly central portion of the fixing seat, a boss being disposed in the sink, a first water inlet/outlet being formed between left side of the sink and a left end of the top layer, a second water inlet/outlet being formed between right side of the sink and a right end of the top layer, the water inlets/outlets communicating with the flow way, a bottom area of the sink being defined as an upper vibration membrane; and

a piezoelectric element, a bottom face of the piezoelectric element being lengthwise fixed on top end of the boss and top face of the fixing seat.

2. The valveless micro impedance pump as claimed in claim 1, wherein the piezoelectric element works by way of uni-morph or bi-morph.

3. The valveless micro impedance pump as claimed in claim 1, wherein the bottom layer, middle layer and top layer are made of electrocasting nickel.

4. The valveless micro impedance pump as claimed in claim 1, wherein the bottom layer is made by means of painting photoresistor, exposure, development, washing out photoresistor, micro-electrocasting and removing photoresistor.

5. The valveless micro impedance pump as claimed in claim 1, wherein the middle layer is made by means of painting photoresistor, exposure, development, washing out photoresistor, micro-electrocasting and removing photoresistor.

6. The valveless micro impedance pump as claimed in claim 1, wherein the top layer is made by means of painting photoresistor, exposure, development, washing out photoresistor, micro-electrocasting, secondary photolithography and removing photoresistor.

7. A valveless micro impedance pump comprising:

a bottom layer formed with an opening;

a top layer overlaid on the middle layer, the top layer having a fixing seat, a sink being formed on a nearly central portion of the fixing seat, two bosses being disposed in the sink, a first water inlet/outlet being formed between left side of the sink and a left end of the top layer, a second water inlet/outlet being formed between right side of the sink and a right end of the top layer, the water inlets/outlets communicating with the flow way, a bottom area of the sink being defined as an upper vibration membrane; and

two piezoelectric elements, bottom faces of the piezoelectric elements being respectively lengthwise fixed on top ends of the bosses and top face of the fixing seat.

8. The valveless micro impedance pump as claimed in claim 7, wherein the bottom layer, middle layer and top layer are made of electrocasting nickel.

9. The valveless micro impedance pump as claimed in claim 7, wherein the bottom layer is made by means of painting photoresistor, exposure, development, washing out photoresistor, micro-electrocasting and removing photoresistor.

10. The valveless micro impedance pump as claimed in claim 7, wherein the middle layer is made by means of painting photoresistor, exposure, development, washing out photoresistor, micro-electrocasting and removing photoresistor.

11. The valveless micro impedance pump as claimed in claim 7, wherein the top layer is made by means of painting photoresistor, exposure, development, washing out photoresistor, micro-electrocasting, secondary photolithography and removing photoresistor.