Micropump based on capillary phenomenon and electrowetting phenomenon
Technical Field
The invention relates to the field of micropump devices, in particular to a micropump based on a capillary phenomenon and an electrowetting phenomenon.
Background
With the wider application of the microfluidic technology, the micropump is the heart of the microfluidic system and is a power source for conveying microfluid, and can accurately control and drive the flow and the flow of fluid in a pipeline. The method is widely applied to various fields and is an important mark for measuring the microfluid development level of a country. At present, the operation of the micro pump is realized based on the piezoelectric vibrator under the action of inverse voltage effect deformation. Under the action of alternating current, the vibrator made of the piezoelectric material can vibrate repeatedly, so that the volume of the cavity of the piezoelectric pump changes periodically, and the fluid is transported. However, since the piezoelectric pump has a structure such as a piezoelectric vibrator and a cantilever, the service life of the piezoelectric pump is not long, and further, since the structure of the piezoelectric pump is complicated, it is difficult to further reduce the volume of the piezoelectric pump to a micrometer scale or even a micrometer scale or less. The fields like MEMS, aerospace, medical treatment, chemical analysis, vascular robot, and lab-on-a-chip all have high requirements on the service life, reliability, and volume of the piezoelectric pump.
Disclosure of Invention
The invention aims to overcome the existing problems and provides a micropump based on a capillary phenomenon and an electrowetting phenomenon, which has no mechanical structure, simple design, small volume and wide application range; because no mechanical structure is arranged, the micro pump can be prevented from generating mechanical abrasion in the using process, thereby prolonging the service life of the micro pump and having higher reliability.
The purpose of the invention is realized by the following technical scheme:
a micropump based on a capillary phenomenon and an electrowetting phenomenon comprises a liquid inlet, a liquid outlet and a liquid channel arranged between the liquid inlet and the liquid outlet, wherein one end of the liquid channel is communicated with the liquid inlet, and the other end of the liquid channel is communicated with the liquid outlet; it is characterized in that the preparation method is characterized in that,
an electrowetting power mechanism for pumping the liquid from the liquid inlet to the liquid outlet is arranged on the liquid channel; the electrowetting power mechanism comprises a pump cavity arranged on a liquid channel, a dielectric material hydrophobic layer arranged in the pump cavity, a first electrode plate and a second electrode plate which are arranged between the inner wall of the pump cavity and the dielectric material hydrophobic layer and used for driving liquid in the liquid channel to move upwards along the pump cavity; the lower end of the pump cavity is communicated with the liquid channel, and the upper end of the pump cavity is provided with an opening;
and a one-way flow resistance mechanism which enables liquid to flow from the liquid inlet along the liquid outlet is arranged on the liquid channel.
The working principle of the micropump based on the capillary phenomenon and the electrowetting phenomenon is as follows:
when the device works, firstly, the liquid channel is filled with liquid to be pumped under the action of external hydrostatic pressure, and due to the fact that the dielectric material hydrophobic layer is arranged in the pump cavity, the capillary phenomenon cannot occur in the pump cavity, and the contact surface of the liquid and air cannot rise; then, the first electrode plate is connected with the anode of an external direct current power supply, the second electrode plate is connected with the cathode of the external direct current power supply, and the liquid in the pump cavity generates an electrowetting phenomenon (namely, the surface energy of the contact surface of the hydrophobic layer of the dielectric material and the liquid is changed by changing the electric potential between the electrode plate and the liquid, and finally the contact angle between the electrode plate and the liquid is changed); so that the liquid in the pump cavity rises along the axis direction of the pump cavity, and the pumped liquid is conveyed to the pump cavity from the liquid channel, and the upward water absorption of the pump cavity is realized; then, the direct current power supply of the first electrode plate and the second electrode plate is cut off, and the liquid in the pump cavity can not generate the capillary phenomenon, so the liquid in the pump cavity descends and is discharged into the liquid channel under the action of self gravity; when the first electrode plate and the second electrode plate are respectively periodically and simultaneously disconnected and connected with the positive electrode and the negative electrode of an external direct-current power supply, the pump cavity can periodically absorb water and drain water to the liquid channel, and under the action of the one-way flow resistance mechanism, pumped liquid is driven to flow from the liquid inlet to the liquid outlet macroscopically, so that a power effect is provided for conveying the liquid.
In a preferable embodiment of the present invention, the one-way flow resistance mechanism includes two tapered flow passages respectively disposed at two ends of the liquid passage, the two tapered flow passages are distributed left and right with respect to the pump cavity, and a width of each tapered flow passage gradually increases toward the liquid outlet. When the liquid in the liquid channel is periodically sucked and drained due to the periodic ascending and descending of the liquid in the pump cavity, the flow resistance is smaller when the liquid flows from the small width direction to the large width direction of the conical flow channel on the conical flow channel as the width of the conical flow channel is gradually increased towards the liquid outlet; when the liquid flows from the direction of the large width to the small width of the tapered flow channel, the flow resistance is large; thus, the pumped liquid is driven to flow from the liquid inlet to the liquid outlet macroscopically. In addition, the conical flow channel is arranged, so that the structure is simple, mechanical abrasion is avoided, and the service life of the micropump is prolonged.
Further, the angle of the tapered flow passage is 53 degrees, and the advantage is that the pumped liquid can be better formed into a one-way flow effect by setting the angle of the tapered flow passage to 53 degrees, so that the pumping efficiency of the liquid is improved.
In a preferred embodiment of the present invention, a spacer for preventing an electrical conduction between the first electrode plate and the second electrode plate is disposed between the first electrode plate and the second electrode plate. Through the arrangement of the isolating pad, the first electrode plate and the second electrode plate cannot be contacted with each other, an insulating effect is achieved, the two electrode plates do not conduct electricity, and the fact that the positive and negative power supplies are periodically connected and disconnected between the first electrode plate and the second electrode plate is guaranteed.
Furthermore, the barrier pad is dielectric hydrophobic material, connects on the dielectric material hydrophobic layer, and its benefit lies in, can strengthen between first electrode board and the second electrode board leakproofness, more effectively avoids taking place electrically conductive phenomenon and more being favorable to liquid to flow in the pump chamber between first electrode board and the second electrode board.
Preferably, the cross sections of the liquid inlet, the liquid outlet, the liquid channel, the pump cavity and the tapered flow passage are rectangular.
Preferably, the cross-sections of the liquid inlet, the liquid outlet, the liquid passage, the pump chamber and the tapered flow passage are circular.
Compared with the prior art, the invention has the following beneficial effects:
1. according to the invention, through the characteristics of capillary phenomenon and electrowetting phenomenon, the first electrode plate and the second electrode plate are periodically connected with the positive electrode and the negative electrode of an external direct-current power supply, so that the pump cavity periodically absorbs water and discharges water to a liquid channel, and power is provided for conveying liquid; the micropump has no mechanical structure, is simple in design, cannot cause abrasion of each part in the working process, and effectively prevents the parts from being damaged, so that the service life of the micropump is prolonged, and the micropump is high in reliability.
2. In the invention, because of no complex mechanical structure, the manufacturing process is simple, the volume of the micropump can be further reduced, the mass is lighter, the application range is wider, the micropump can work under the characteristic size of micron order, and the micropump can be applied to the fields with higher requirements on the volume of the micropump, such as fields of MEMS, aerospace, medical treatment, chemical analysis, vascular robots, chip laboratories and the like.
Drawings
Fig. 1 is a schematic perspective view of a first embodiment of a micro pump based on capillary phenomenon and electrowetting phenomenon according to the present invention.
Fig. 2 is a cross-sectional view of a micro-pump based on capillary phenomenon and electro-wetting phenomenon in the present invention.
Fig. 3 is a partially enlarged view of a portion a in fig. 1.
Fig. 4 is a partially enlarged view of fig. 2 at B.
Detailed Description
In order to make those skilled in the art understand the technical solutions of the present invention well, the following description of the present invention is provided with reference to the embodiments and the accompanying drawings, but the embodiments of the present invention are not limited thereto.
Example 1
Referring to fig. 1-4, a micropump based on capillary phenomenon and electrowetting phenomenon includes a liquid inlet 1, a liquid outlet 2, and a liquid channel 3 disposed between the liquid inlet 1 and the liquid outlet 2, wherein one end of the liquid channel 3 is communicated with the liquid inlet 1, and the other end is communicated with the liquid outlet 2; the liquid pump is characterized in that an electrowetting power mechanism 4 for pumping the liquid from the liquid inlet 1 to the liquid outlet 2 is arranged on the liquid channel 3; the electrowetting power mechanism 4 comprises a pump cavity 4-1 arranged on the liquid channel 3, a dielectric material hydrophobic layer 4-2 arranged in the pump cavity 4-1, and a first electrode plate 4-3 and a second electrode plate 4-4 which are arranged between the inner wall of the pump cavity 4-1 and the dielectric material hydrophobic layer 4-2 and used for driving liquid in the liquid channel 3 to move upwards along the pump cavity 4-1; the lower end of the pump cavity 4-1 is communicated with the liquid channel 3, and the upper end is provided with an opening; the liquid channel 3 is provided with a one-way flow resistance mechanism 5 for enabling liquid to flow from the liquid inlet 1 along the liquid outlet 2.
Referring to fig. 1-4, the one-way flow resistance mechanism 5 includes two tapered flow passages 5-1 respectively disposed at two ends of the liquid passage 3, the two tapered flow passages 5-1 are distributed left and right with respect to the pump cavity 4-1, and a width of each tapered flow passage 5-1 gradually increases toward the liquid outlet 2. When the liquid periodically rises and falls in the pump cavity 4-1 to realize the periodic water absorption and drainage of the liquid in the liquid channel 3, the width of the conical flow channel 5-1 is gradually increased towards the liquid outlet 2, and when the liquid flows from the small width direction of the conical flow channel 5-1 to the large width direction on the conical flow channel 5-1, the flow resistance is small; when the liquid flows from the direction of the large width to the small width of the conical flow channel 5-1, the flow resistance is large; thus, the pumped liquid is driven macroscopically to flow from the inlet 1 to the outlet 2. In addition, the conical flow channel 5-1 is arranged, so that the structure is simple, mechanical abrasion is avoided, and the service life of the micropump is prolonged.
Referring to fig. 1 to 4, the angle of the tapered flow channel 5-1 is 53 °, which is advantageous in that, by setting the angle of the tapered flow channel 5-1 to 53 °, the pumped liquid can be better formed into a unidirectional flow effect, thereby improving the pumping efficiency of the liquid.
Referring to fig. 1 to 4, a blocking pad 6 for preventing a conductive function between the first electrode plate 4-3 and the second electrode plate 4-4 is disposed therebetween. By arranging the isolating pad 6, the first electrode plate 4-3 and the second electrode plate 4-4 cannot be contacted with each other to play an insulating role, so that the two electrode plates do not generate a conducting effect, and the periodical connection and disconnection of a positive power supply and a negative power supply between the first electrode plate 4-3 and the second electrode plate 4-4 are ensured.
Referring to fig. 1-4, the barrier pad 6 is made of a dielectric hydrophobic material and is connected to the hydrophobic layer 4-2 made of the dielectric material, which is advantageous in enhancing the sealing between the first electrode plate 4-3 and the second electrode plate 4-4, more effectively avoiding the occurrence of a conductive phenomenon between the first electrode plate 4-3 and the second electrode plate 4-4, and further facilitating the flow of liquid in the pump chamber 4-1.
Referring to fig. 1 to 4, the liquid inlet 1, the liquid outlet 2, the liquid passage 3, the pump chamber 4-1, and the tapered flow passage 5-1 have a rectangular cross section.
Referring to fig. 1 to 4, the micro pump based on the capillary phenomenon and the electrowetting phenomenon operates according to the following principle:
when the device works, firstly, the liquid channel 3 is filled with liquid to be pumped under the action of external hydrostatic pressure, and the pump cavity 4-1 is internally provided with the dielectric material hydrophobic layer 4-2, so that the capillary phenomenon cannot occur in the pump cavity 4-1, and the contact surface of the liquid and air cannot rise; then, the first electrode plate 4-3 is connected with the anode of an external direct current power supply, the second electrode plate 4-4 is connected with the cathode of the external direct current power supply, and the liquid in the pump cavity 4-1 generates an electrowetting phenomenon (namely, the surface energy of the contact surface of the dielectric material hydrophobic layer 4-2 and the liquid is changed by changing the electric potential between the electrode plates and the liquid, and finally the contact angle between the two is changed); so that the liquid in the pump cavity 4-1 rises along the axial direction of the pump cavity 4-1, and the pumped liquid is conveyed to the pump cavity 4-1 from the liquid channel 3, and the pump cavity 4-1 sucks water upwards; then, the direct current power supply of the first electrode plate 4-3 and the second electrode plate 4-4 is cut off, and the liquid in the pump cavity 4-1 can not generate the capillary phenomenon, so the liquid in the pump cavity 4-1 descends and is discharged into the liquid channel 3 under the action of self gravity; when the positive electrode and the negative electrode of the external direct current power supply are periodically disconnected and connected with the second electrode plate 4-4 and the first electrode plate 4-3 respectively, the pump cavity 4-1 can periodically absorb and discharge water to the liquid channel 3, and the pumped liquid is driven to flow from the liquid inlet 1 to the liquid outlet 2 macroscopically under the action of the one-way flow resistance mechanism 5, so that a power effect is provided for conveying the liquid.
Example 2
The other structure of this embodiment is the same as embodiment 1, except that: the cross sections of the liquid inlet 1, the liquid outlet 2, the liquid channel 3, the pump cavity 4-1 and the conical flow channel 5-1 are circular.
Example 3
The other structure of this embodiment is the same as embodiment 1, except that: the one-way flow resistance mechanism 5 comprises two one-way valves; the two one-way valves are respectively arranged at two ends of the liquid channel 3 and are distributed left and right relative to the pump cavity 4-1. The one-way flow of the pumped liquid is realized by arranging the one-way valve.
The present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents and are included in the scope of the present invention.