CN107790204A - A kind of microlayer model Drive And Its Driving Method based on electric FREQUENCY CONTROL - Google Patents

Abstract

The invention discloses a micro-droplet driving device based on electric frequency control and a driving method thereof. Through the design of a double-substrate microfluidic chip, a method of adjusting the voltage frequency applied to the chip electrode without changing the voltage amplitude is adopted. Realize the driving of micro-droplets on the chip. The invention has the advantages that the electrode structure of the device is simple, and independent addressable micro-electrodes are not required; the operation is convenient, and the voltage amplitude between the upper and lower substrates does not need to be changed, and the droplet can be driven to move back and forth by controlling the frequency.

Description

A micro-droplet driving device and its driving method based on electric frequency control

technical field

The invention belongs to the field of microfluidic technology, and in particular relates to a micro droplet driving device based on electric frequency control and a driving method thereof.

Background technique

Microfluidics is a science and technology that can precisely control and manipulate micron-scale fluids. In recent years, as a representative of lab-on-a-chip, microfluidic chips have been widely used in research fields such as separation analysis, chemical synthesis, medical diagnostics, and cell biology.

In the field of microfluidic chips, the widely used droplet driving methods include electrowetting, thermal capillary, and surface acoustic wave. Among them, the key components of the surface acoustic wave method need to use single crystal materials, which are expensive, and the manufacturing process requires high precision and harsh conditions; the thermal capillary method is not suitable for the analysis of thermally unstable substances such as enzymes and proteins in micro-droplets; The wet method can realize the manipulation of a single micro-droplet, and usually requires a series of independently addressable micro-electrodes and a programmable electrode switch control system to make the micro-droplet move in the direction of the pressurized electrode.

Contents of the invention

The purpose of the present invention is to provide a micro-droplet driving device and its driving method based on electric frequency control, and propose a brand-new driving mode, which solves the problem of directional driving of droplets under stable voltage.

The technical solution to realize the object of the present invention is: a micro-droplet driving device based on electric frequency control, including a lower substrate, a lower substrate electrode, a first dielectric layer, a second dielectric layer, a third dielectric layer, and a lower substrate hydrophobic layer , the hydrophobic layer of the upper substrate, the upper substrate electrode and the upper substrate; the lower substrate is in a second-order ladder shape, and the upper substrate is arranged in parallel directly above the lower substrate, forming a first cavity and a second cavity between the two, and the first cavity The height D ₁ of the second cavity and the height D ₂ of the second cavity satisfy 4D ₂ <D ₁ <7D ₂ , the micro-droplet to be driven is located between the first cavity and the second cavity; the top surface of the lower substrate is coated with the lower substrate Electrode, the top surface of the lower substrate electrode is coated with the first dielectric layer, the second dielectric layer and the third dielectric layer, and the top surface of the first dielectric layer, the second dielectric layer and the third dielectric layer is coated with the hydrophobic layer of the lower substrate; the bottom surface of the upper substrate The upper substrate electrode is coated, and the upper substrate hydrophobic layer is coated on the bottom surface of the upper substrate electrode.

The thickness of the first dielectric layer in the first cavity is d ₁ , the thickness of the third dielectric layer in the second cavity is d ₂ , d ₁ and d ₂ satisfy 7d ₁ <d ₂ <12d ₁ , and the thickness of the third dielectric layer in the second cavity is d 1 . The thickness of the second dielectric layer between the _first cavity and the second cavity is any value between d1 and _d2 .

The micro-droplet is a single-component or multi-component conductive liquid.

A driving method of a micro-droplet driving device based on electric frequency control, the method is as follows: when the voltage frequency applied to the lower substrate electrode and the upper substrate electrode is below 1 kHz, the micro-droplet to be driven moves to the first cavity, When the frequency of the voltage applied to the lower substrate electrode and the upper substrate electrode is above 50kHz, the micro droplet to be driven moves toward the second cavity.

The effective value range of the voltage mentioned above is 50~200V.

Compared with the prior art, the present invention has the remarkable advantage that the electrode structure adopted is simple, and a series of independently addressable microelectrodes are not needed. The operation of the droplet drive is convenient, and the droplet can be driven to move back and forth only by controlling the frequency without changing the voltage amplitude between the upper and lower substrates.

Description of drawings

FIG. 1 is a structural diagram of a micro-droplet driving device based on electric frequency control of the present invention.

Detailed ways

A micro-droplet drive device based on electrical frequency control, through the design of a double-substrate microfluidic chip, using the different dielectric response characteristics of the droplet under different frequency voltages, the frequency of the voltage applied to the electrode of the chip is adjusted without requiring The method of changing the voltage amplitude realizes the driving of micro-droplets on the chip.

In conjunction with FIG. 1, a micro droplet drive device based on electrical frequency control, including a lower substrate 1, a lower substrate electrode 2, a first dielectric layer 3-1, a second dielectric layer 3-2, and a third dielectric layer 3-3 , the lower substrate hydrophobic layer 4-1, the upper substrate hydrophobic layer 4-2, the upper substrate electrode 6 and the upper substrate 7; The first cavity 9 and the second cavity 5 are formed between them, the height D 1 of the first cavity 9 and the height D ₂ of the second cavity 5 satisfy 4D ₂ <D ₁ <7D ₂ , the droplet to be driven ₈ Located between the first cavity 9 and the second cavity 5; the top surface of the lower substrate 1 is coated with the lower substrate electrode 2, and the top surface of the lower substrate electrode 2 is coated with the first dielectric layer 3-1 and the second dielectric layer 3-2 and the third dielectric layer 3-3, the top surface of the first dielectric layer 3-1, the second dielectric layer 3-2 and the third dielectric layer 3-3 are coated with the hydrophobic layer 4-1 of the lower substrate; the bottom surface of the upper substrate 7 is coated with The upper substrate electrode 6, the bottom surface of the upper substrate electrode 6 is coated with the upper substrate hydrophobic layer 4-2.

The thickness of the first dielectric layer 3-1 located in the first cavity 9 is d ₁ , the thickness of the third dielectric layer 3-3 located in the second cavity 5 is d ₂ , and d ₁ and d ₂ satisfy 7d ₁ < d ₂ <12d ₁ ; the thickness of the second dielectric layer 3 - 2 located between the first cavity 9 and the second cavity 5 can be any value between d ₁ and d ₂ .

The micro-droplet 8 is a single-component or multi-component conductive liquid.

The one-component conductive liquid, such as saline solution.

The multi-component conductive liquid, such as cell culture fluid.

A driving method of a micro-droplet driving device based on electric frequency control, the method is as follows: when the voltage frequency applied to the lower substrate electrode 2 and the upper substrate electrode 6 is below 1kHz, the micro-droplet 8 to be driven is directed toward the first space. The cavity 9 moves, and after the power is cut off, the micro-droplet stops moving and remains at the position before the power-off moment. When the frequency of the voltage applied to the lower substrate electrode 2 and the upper substrate electrode 6 is above 50 kHz, the micro-droplet 8 to be driven moves to the second cavity 5, and after the power is turned off, the micro-droplet stops moving and remains at the moment of power-off at the previous position. During the movement of the micro-droplet 8 , it is controlled not to make the micro-droplet 8 completely enter the first cavity 9 or the second cavity 5 , otherwise the micro-droplet 8 cannot be driven again. The effective value range of the voltage mentioned above is 50~200V.

The preparation process of the micro-droplet driving device based on electric frequency control of the present invention is as follows:

Prepare the lower substrate 1

1. A glass plate or an insulating silicon wafer is used as the base of the lower substrate 1, and a hollow groove is etched on one side of the lower substrate 1 by wet etching to form a second-order ladder shape, and the lower substrate 1 is obtained.

2. Prepare a layer of metal electrodes, such as aluminum electrodes, on the upper surface of the lower substrate 1 by using a coating process such as magnetron sputtering or evaporation to obtain the lower substrate electrode 2 .

3. A dielectric layer with a thickness of _d2 is formed on the lower substrate electrode 2 by chemical vapor deposition or vacuum coating, and an insulating material with a high dielectric constant and strong breakdown resistance is preferred, such as Parylene.

4. Etch the dielectric layer in the hollow part of the lower substrate ₁ into a first dielectric layer 3-1 with a thickness of d1 by plasma etching, and at the same time obtain the second dielectric layer 3-2 and the third dielectric layer Layer 3-3.

5. The lower substrate hydrophobic layer 4-1 is prepared on the first dielectric layer 3-1, the second dielectric layer 3-2 and the third dielectric layer 3-3 by spin coating, and the material is Teflon-AF or Cytop.

Prepare upper substrate 7

1. A glass plate is used as the base of the upper substrate 7, and a layer of conductive film (the upper substrate electrode 6) is formed by PECVD (plasma enhanced chemical vapor deposition) or evaporation or sputtering, preferably a film layer with high light transmittance materials, such as indium tin oxide, etc.

2. Prepare the upper substrate hydrophobic layer 4-2 on the conductive film (upper substrate electrode 6) by spin coating, and use Teflon-AF or Cytop as the material.

The electrodes used in the present invention have a simple structure and do not require a series of independently addressable microelectrodes. The operation of the droplet drive is convenient, and the droplet can be driven to move back and forth only by controlling the frequency without changing the voltage amplitude between the upper and lower substrates.

Claims (5)

1. A kind of 1. microlayer model drive device based on electric FREQUENCY CONTROL, it is characterised in that：Including infrabasal plate（1）, infrabasal plate electrode （2）, first medium layer（3-1）, second dielectric layer（3-2）, the 3rd dielectric layer（3-3）, infrabasal plate hydrophobic layer（4-1）, upper substrate Hydrophobic layer（4-2）, upper substrate electrode（6）And upper substrate（7）；Infrabasal plate（1）For second order stairstepping, upper substrate（7）It is arranged in parallel In infrabasal plate（1）Surface, form the first cavity between the two（9）With the second cavity（5）, the first cavity（9）Height D₁ With the second cavity（5）Height D₂Meet 4D₂<D₁ <7D₂, microlayer model to be driven（8）Positioned at the first cavity（9）It is empty with second Chamber（5）Between；Infrabasal plate（1）Top surface coats infrabasal plate electrode（2）, infrabasal plate electrode（2）Top surface coats first medium layer（3- 1）, second dielectric layer（3-2）With the 3rd dielectric layer（3-3）, first medium layer（3-1）, second dielectric layer（3-2）With the 3rd medium Layer（3-3）Top surface coats infrabasal plate hydrophobic layer（4-1）；Upper substrate（7）Coated on bottom side is covered with electrode of substrate（6）, upper substrate electrode（6） Coated on bottom side is covered with substrate hydrophobic layer（4-2）.
2. 2. the microlayer model drive device according to claim 1 based on electric FREQUENCY CONTROL, it is characterised in that：It is empty positioned at first Chamber（9）Interior first medium layer（3-1）Thickness be d₁, positioned at the second cavity（5）The 3rd interior dielectric layer（3-3）Thickness d₂, d₁And d₂Meet 7d₁ <d₂ <12d₁, positioned at the first cavity（9）With the second cavity（5）Between second dielectric layer（3-2）Thickness For d₁To d₂Between arbitrary value.
3. 3. the microlayer model drive device according to claim 1 based on electric FREQUENCY CONTROL, it is characterised in that：Described micro- liquid Drop（8）For one pack system or multi-component conductive liquid.
4. 4. the driving based on the microlayer model drive device based on electric FREQUENCY CONTROL described in any one in the claims 1-3 Method, it is characterised in that method is as follows：When being applied to infrabasal plate electrode（2）With upper substrate electrode（6）On electric voltage frequency exist During below 1kHz, microlayer model to be driven（8）To the first cavity（9）Motion, when being applied to infrabasal plate electrode（2）With upper substrate electricity Pole（6）On electric voltage frequency in more than 50kHz, microlayer model to be driven（8）To the second cavity（5）Motion.
5. 5. the driving method of the microlayer model drive device according to claim 4 based on electric FREQUENCY CONTROL, it is characterised in that： The valid value range of voltage described above is 50 ~ 200V.