CN101301989A - A microfluidic driving and mixing structure and its application method - Google Patents

Abstract

The invention discloses a comb electrode-based microfluid driving and mixing structure and an application method thereof, belonging to the technical field of microfluid driving and mixing. The structure comprises a micropipe upper cover sheet 1 and a micropipe lower cover sheet 4, on the micropipe upper cover sheet, several broadband electrodes I2 and equal number of narrowband electrodes I3 are arranged, and all broadband electrodes I and all narrowband electrodes I are covered They are respectively connected together to form a comb-like structure and connected to their corresponding electrode terminals; the lower cover sheet 4 of the microchannel also has the same structure, but the arrangement of the electrode pairs on the upper cover sheet is opposite to that on the lower cover sheet 4 . In addition, a method of using the structure is also disclosed. The present invention can control the mixing process of the microfluid in the micropipe, and improves the mixing efficiency of the microfluid; meanwhile, the matrix material of the micropipe is polydimethylsiloxane (PDMS), and glass or silicon wafers are used as upper and lower covers, which is easy Realize the integration and mass production of microfluidic hybrid chips.

Description

A microfluidic driving and mixing structure and its application method

Technical field:

The invention relates to a microfluid driving and mixing structure based on a comb-like electrode and an application method thereof, and belongs to the technical field of microfluid driving and mixing in micromechanical electronic systems (MEMS).

Background technique:

Because the fluid movement in the microchannel is a significant laminar flow movement, the fluid mixing technology in the microchannel becomes the key technology of the miniature biochemical analysis instrument. Existing microfluidic mixing methods can be divided into two categories: passive mixing methods that use complex channel structures to generate disordered mixed flow; active mixing methods that improve fluid mixing efficiency by changing external conditions such as pressure and electric field.

The active mixing method uses external mechanical or electromagnetic force to disturb the laminar flow state of the fluid to improve the mixing effect of microfluidics. M.Mpholoa and A.B.D.Brownb et al. designed an asymmetric electrode structure, using polytetrafluoroethylene (PTFE) as a micro-channel matrix material, and mechanically sandwiched PTFE between two glass coverslips to form a micro-channel; in the micro-channel The bottom is designed with wide-band electrodes and narrow-band electrodes arranged at intervals, and is driven by AC electrostatic force to realize the fluid drive in the micropipe. This method can partially realize fluid mixing in microchannels while realizing microfluidic drive. The existing problems are: (1) The structure cannot actively control the mixing effect of the microfluid, and the mixing efficiency is low; (2) Due to the limitation of the polytetrafluoroethylene (PTFE) material, the microfluidic pipeline cannot be miniaturized and batched. production.

Invention content:

The purpose of the present invention is to solve the following problems in the above-mentioned active microfluidic mixing technology: (1) the microfluidic mixing efficiency is low, and the active control of the mixing efficiency cannot be realized; The manufacturing process is complicated, and the integration degree of the microfluidic chip is low.

Referring to Fig. 1 to Fig. 3, the present invention proposes a microfluidic driving and mixing structure, which is a structure comprising an upper cover 1, a pair of electrodes with a comb-like structure on the upper cover 1, a micropipe substrate 9, and a lower cover 4. The upper comb structure electrode pair and the sandwich structure of the lower cover sheet 4; the upper cover sheet 1 is arranged with a number of broadband electrodes I 2 and an equal number of narrow band electrodes I 3, and all the broadband electrodes I 2 are connected together to form a comb structure And connected to electrode terminal I 7, all narrow-band electrodes I 3 are connected together to form a comb structure and connected to electrode terminal II 8, each pair of adjacent broadband electrodes I 2 and narrow-band electrodes I 3 form a group of electrode pairs, the electrodes Pairs are arranged in order to form comb-shaped electrode pairs on the upper cover sheet 1;

On the lower cover sheet 4, several broadband electrodes II 5 and equal number of narrow-band electrodes II 6 are arranged at intervals, all broadband electrodes II 5 are connected together to form a comb structure and connected to electrode terminal III 9, and all narrow-band electrodes II 6 are connected to Together form a comb structure and connect to electrode terminal IV 10, each pair of adjacent broadband electrodes II 5 and narrow band electrodes II 6 form a group of electrode pairs, and the electrode pairs are arranged in order to form a comb-shaped electrode pair on the lower cover sheet 4 .

The arrangement of the electrode pairs on the upper cover 1 is opposite to the arrangement of the electrode pairs on the lower cover 4, that is, the arrangement order of the electrode pairs on the upper cover is narrowband electrodes-broadband electrodes, and the arrangement order of the electrode pairs on the lower cover is broadband electrodes-narrowband electrodes. electrode. Alternatively, the arrangement sequence of the electrode pairs on the upper cover sheet is broadband electrodes-narrow-band electrodes, and the arrangement order of the electrode pairs on the lower cover sheet is narrow-band electrodes-broadband electrodes.

The material of the upper cover 1 is silicon or glass, the lower cover 4 is glass or silicon wafer, at least one of the two materials is a transparent medium, and the material of the micropipe substrate 9 is polydimethylsiloxane (PDMS), PDMS It is bonded together with the upper cover 1 and the lower cover 4, and the electrodes on the upper cover 1 and the lower cover 4 are made of metal materials with good electrical conductivity such as platinum.

The method of using the microfluid drive and mixing structure proposed by the present invention is as follows:

1. Connect electrode terminal I 7 and electrode terminal II 8 to the two poles of the first AC power supply respectively, and apply AC power I with adjustable frequency and amplitude; connect electrode terminal III 9 and electrode terminal IV 10 respectively To the two poles of the second AC power supply, apply AC power II with adjustable frequency and amplitude;

2. Turn on the AC power source I to make the fluid in the micro-channel move from one end of the micro-channel to the other end of the micro-channel, and turn on the AC power source II to make the fluid in the micro-channel move in the opposite direction to that when the AC power source I is turned on. Turn on AC power supply I or AC power supply II as needed, and drive the microfluids to be mixed to the microchannel area where the electrode pair is located.

3. Turn on the AC power supply I and the AC power supply II at the same time, apply the same power supply frequency and voltage, so that the microfluid is mixed in the microchannel area where the electrode pair is located.

4. According to the requirements of the mixing degree of the microfluid and the properties of the microfluid in the micropipe, control the duration, power frequency and voltage amplitude in step 3, so that the microfluid in the pipe is fully mixed.

5. According to the requirements of the movement direction of the microfluid, turn off the AC power supply I or the AC power supply II, and use the AC power supply II or the AC power supply I to drive the mixed microfluid out of the microchannel area where the electrode pair is located.

The beneficial effects of the present invention are: by fabricating two sets of comb-like electrode structures in which the electrode pairs are arranged in opposite directions in the micro-pipe, under the action of an external alternating electric field, the mixing process of the micro-fluid in the micro-pipe can be controlled, and the efficiency of the micro-fluid is improved. Mixing efficiency; in addition, polydimethylsiloxane (PDMS) is used as the matrix material of the micropipe, and glass or silicon wafers are used as the upper and lower covers, which is easy to realize the integration and mass production of microfluidic hybrid chips.

Description of drawings:

Figure 1 Microfluidic driving and mixing structure based on comb electrodes

Figure 2 A-A view of Figure 1

Figure 3 Schematic diagram of comb electrode structure

In the figure, 1-upper cover sheet, 2-broadband electrode I, 3-narrowband electrode I, 4-lower cover sheet, 5-broadband electrode II, 6-narrowband electrode II, 7-electrode terminal I, 8-electrode terminal II , 9-microchannel matrix.

Detailed ways:

Specific embodiment 1:

Referring to Fig. 1, Fig. 2, a kind of microfluidic driving and mixing structure that the present embodiment proposes, the upper cover sheet 1 material is glass, the broadband electrode I2 and the narrowband electrode I3 material that is positioned at the upper cover sheet 1 are platinum, the lower cover Sheet 4 is glass, and the broadband electrode II 5 and the narrowband electrode II 6 material on the lower cover sheet 4 are platinum, and the thickness of the platinum electrode is 100 nanometers.

The broadband electrode I 2 on the upper cover 1 and the broadband electrode II 5 on the lower cover 4 have a width of 15 microns, the narrow band electrode I 3 on the upper cover 1 and the narrow band electrode on the lower cover 4 II 6 has a width of 5 microns.

The arrangement order of the electrode pairs on the upper cover 1 is from left to right narrow-band electrode-broadband electrode, a total of 20 pairs of electrodes, forming a comb electrode array; the arrangement order of the electrode pairs on the lower cover 4 is from left to right broadband Electrodes - narrow-band electrodes, a total of 20 pairs of electrodes, forming a comb electrode array.

The spacing between broadband electrodes and narrowband electrodes is 5 μm, and the spacing between electrode pairs is 25 μm.

The working process of this microfluid drive and mixing structure proposed by the present invention is as follows:

1. Connect electrode terminal I 7 and electrode terminal II 8 to the two poles of the first AC power supply respectively; connect electrode terminal III 9 and electrode terminal IV 10 to the two poles of the second AC power supply respectively;

2. Turn on the AC power supply I and apply the AC power supply I with a frequency of 2000 Hz and an amplitude of 5 V, then the fluid will move in the micro-pipe, and the micro-fluid medium to be mixed will be driven to the comb-shaped electrode area.

3. Turn on the AC power supply I and the AC power supply II at the same time, and apply an AC power supply with a frequency of 2000 Hz and an amplitude of 5 V to the two AC power supplies at the same time, then the microfluids will be mixed in the microchannel area where the electrode pair is located.

4. Continue step 3 for 30 seconds, and the microfluid in the microchannel is fully mixed.

5. Turn off the AC power supply II, so that the AC power supply I drives the mixed microfluid to move in the micropipe, and the microfluid is driven out of the micropipe area where the electrode pair is located.

Specific embodiment 2:

Another microfluid drive and mixing structure proposed in this embodiment, the material of the upper cover sheet 1 is glass, the material of the broadband electrode I2 and the narrowband electrode I3 positioned on the upper cover sheet 1 is platinum, and the thickness of the platinum electrode is 80 nanometers. The cover sheet 4 is a silicon wafer, and the material of the broadband electrode II 5 and the narrowband electrode II 6 on the lower cover sheet 4 is metal aluminum, and the thickness of the aluminum electrode is 80 nanometers.

The arrangement order of the electrode pairs on the upper cover sheet 1 is from left to right wideband electrode-narrowband electrode, a total of 50 pairs of electrodes, forming a comb electrode array; the arrangement order of the electrode pairs on the lower cover sheet 4 is from left to right narrowband electrode Electrode-broadband electrode, a total of 50 pairs of electrodes, forming a comb electrode array.

The broadband electrode I 2 on the upper cover 1 and the broadband electrode II 5 on the lower cover 4 have a width of 15 microns, the narrow band electrode I 3 on the upper cover 1 and the narrow band electrode on the lower cover 4 II 6 is 3 microns wide.

The spacing between broadband electrodes and narrowband electrodes is 5 μm, and the spacing between electrode pairs is 20 μm.

The working process of this microfluid drive and mixing structure proposed by the present invention is as follows:

1. Connect electrode terminal I 7 and electrode terminal II 8 to the two poles of the first AC power supply respectively; connect electrode terminal III 9 and electrode terminal IV 10 to the two poles of the second AC power supply respectively;

2. Turn on the AC power supply I and apply the AC power supply I with a frequency of 1500 Hz and an amplitude of 3 V, then the fluid will move in the micro-pipe, and the micro-fluid medium to be mixed will be driven to the comb-shaped electrode area.

3. Turn on the AC power supply I and the AC power supply II at the same time, and apply an AC power supply with a frequency of 1500 Hz and an amplitude of 3 V to the two AC power supplies at the same time, then the microfluids will be mixed in the microchannel area where the electrode pair is located.

4. Continue the voltage time of the third step for 3 minutes, and the microfluid in the microchannel is fully mixed.

5. Turn off the AC power supply I, so that the AC power supply II drives the mixed microfluid to move in the micropipe, and the microfluid is driven out of the micropipe area where the electrode pair is located.

Claims (7)

1. A microfluidic driving and mixing structure, comprising successively a pair of comb-like structure electrodes on the upper cover sheet (1), the upper cover sheet (1), a microchannel substrate (9), and a comb on the lower cover sheet (4) Shaped structure electrode pairs and the lower cover sheet (4); on the upper cover sheet (1), there are several broadband electrodes I (2) and equal number of narrow-band electrodes I (3), and all the broadband electrodes I (2) are connected to Together form a comb structure and connect to electrode terminal I (7), all narrowband electrodes I (3) are connected together to form a comb structure and connect to electrode terminal II (8), each pair of adjacent broadband electrodes I (2 ) and narrow-band electrodes I (3) form a group of electrode pairs; on the lower cover sheet (4), there are several broadband electrodes II (5) and equal number of narrow-band electrodes II (6), and all broadband electrodes II (5) Connected together to form a comb structure and connected to electrode terminal III (9), all narrowband electrodes II (6) are connected together to form a comb structure and connected to electrode terminal IV (10), each pair of adjacent broadband electrodes II (5) and the narrow-band electrode II (6) form a group of electrode pairs; the arrangement of the electrode pairs on the upper cover (1) is opposite to that on the lower cover (4); the upper cover (1) or the lower At least one material in the cover sheet (4) is a transparent medium. 2. A microfluidic driving and mixing structure as claimed in claim 1, characterized in that, the electrode pairs on the described upper cover sheet (1) are arranged in the order of narrow-band electrode-broadband electrode, and the described lower cover sheet The arrangement order of the electrode pairs in (2) is broadband electrode-narrowband electrode. 3. A microfluidic driving and mixing structure as claimed in claim 1, characterized in that, the electrode pairs on the described upper cover sheet (1) are arranged in the order of broadband electrodes-narrow band electrodes, and the described lower cover sheet The arrangement order of the electrode pairs in (2) is narrowband electrode-broadband electrode. 4. A microfluidic driving and mixing structure as claimed in claim 1, characterized in that the material of the upper cover (1) is silicon or glass. 5. A microfluidic driving and mixing structure as claimed in claim 1, characterized in that, the material of the lower cover (4) is glass or a silicon wafer. 6. A microfluid driving and mixing structure as claimed in claim 1, characterized in that, the material of the micropipe matrix (9) is polydimethylsiloxane (PDMS). 7. A method for using the microfluid drive and mixing structure as claimed in claim 1, comprising the following steps: Step 1. Connect electrode terminal I (7) and electrode terminal II (8) to the two poles of the first AC power supply respectively, and apply AC power I with adjustable frequency and amplitude; connect electrode terminal III (9) The electrode terminal IV (10) is connected to the two poles of the second AC power supply respectively, and the AC power supply II with adjustable frequency and amplitude is applied to it; Step 2. Turn on the AC power source I, so that the fluid in the micro-channel moves from one end of the micro-channel to the other end of the micro-channel; turn on the AC power source II, so that the movement direction of the fluid in the micro-channel is opposite to that when the AC power source I is turned on. Turn on AC power supply I or AC power supply II as needed, and drive the microfluids to be mixed to the microchannel area where the electrode pair is located. Step 3. Turn on the AC power supply I and the AC power supply II at the same time, apply the same power supply frequency and voltage, and then the microfluids will be mixed in the microchannel area where the electrode pair is located. Step 4. Control the duration, power frequency and voltage amplitude of step 3 according to the requirements of the mixing degree of the microfluid and the properties of the microfluid in the micropipe, so that the microfluid in the pipe is fully mixed. Step 5. According to the requirements of the movement direction of the microfluid, turn off the AC power supply I or the AC power supply II, and use the AC power supply II or the AC power supply I to drive the mixed microfluid out of the microchannel area where the electrode pair is located.

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