CN211216724U - Micro-fluidic chip containing deformable liquid metal electrode - Google Patents

Abstract

The utility model provides a micro-fluidic chip containing a deformable liquid metal electrode, which comprises a substrate; etching a first shape on the substrate; a micro-channel layer is arranged on the substrate; the micro-channels on the micro-channel layer are respectively a first micro-channel, a second micro-channel, a third micro-channel and a fourth micro-channel; the first micro-channel is communicated with the second micro-channel through a third micro-channel; the fourth micro-channel is communicated with the first micro-channel; the first micro-channel and the second micro-channel are respectively used for flowing liquid metal and solution; the fourth micro-channel is communicated with the first micro-channel to form a buffer channel, and the width of the buffer channel is slightly larger than that of the third micro-channel; the other side of the micro-flow channel layer is provided with a through hole for injecting and flowing out liquid metal and solution; the liquid metal and the first shape together form a deformable electrode. The utility model provides a micro-fluidic chip contains the deformable microelectrode based on liquid metal, and the electrode shape is controllable, and the interelectrode distance is adjustable.

Description

A microfluidic chip containing deformable liquid metal electrodes

technical field

The utility model relates to the field of biological detection, in particular to a microfluidic chip comprising a deformable liquid metal electrode.

Background technique

At present, the electrodes used in microfluidic chips are mostly copper electrodes, gold electrodes, platinum electrodes, ITO electrodes, etc., which need to be applied to complex processes such as lithography and sputtering, and the shape of the electrodes cannot be changed once they are fabricated. Also cannot be adjusted. At the same time, the electrodes cannot be reused, and different experiments need to use complex methods to make different chips, which is very expensive. The utility model uses liquid metal instead of metal or ITO to form deformable micro-electrodes for the first time, realizes the manufacture of shape-adjustable electrodes in the microfluidic chip for the first time, and the manufacturing process is simple. The microfluidic chip provided by the utility model includes deformable microelectrodes based on liquid metal, the shape of the electrodes is controllable, and the distance between the electrodes is adjustable, so the application range is wide and the applicability is strong. Liquid metal electrodes are highly conductive and are not prone to breakdown at high voltages. The preparation method is simple, convenient to use, reusable and low cost. (Background patent source 200610043686.8) Disadvantages of the prior art: the use of precious metals has high cost, complicated process, and cannot be recycled. The electrodes are in a fixed shape and cannot be deformed.

Utility model content

In view of this, the present invention provides a microfluidic chip including a deformable liquid metal electrode, the process is simple, the electrode can be deformed and can be recycled, and the cost is low.

In order to solve the above problems, the present invention provides a microfluidic chip containing deformable liquid metal microelectrodes, including:

a substrate; a first shape is etched on the substrate;

A micro-channel layer is arranged on the substrate; the micro-channels on the micro-channel layer are respectively a first micro-channel, a second micro-channel, a third micro-channel and a fourth micro-channel; the The first microfluidic channel is communicated with the second microfluidic channel through the third microfluidic channel; the fourth microfluidic channel is communicated with the first microfluidic channel;

The first microfluidic channel and the second microfluidic channel are respectively used for the flow of liquid metal and solution; the fourth microfluidic channel and the first microfluidic channel are connected as a buffer channel, the width of which is slightly larger than that of the third microfluidic channel. runner;

A through hole is provided on the top of the microfluidic layer for injection and outflow of liquid metal and solution;

The liquid metal and the first shape together form a deformable electrode.

Preferably, the microfluidic layer fabrication material is polydimethylsiloxane (PDMS).

Preferably, the substrate is ITO conductive glass.

Preferably, the liquid metal deformable electrode is made by changing the injection speed of the liquid metal.

Preferably, the width of the first microchannel is 1000 μm, the width of the second microchannel is 100-200 μm, the width of the third microchannel is 80-120 μm, and the width of the fourth microchannel is 150-200 μm.

The primary improvement of the present utility model is that the utility model provides a microfluidic chip containing deformable liquid metal microelectrodes, comprising: a substrate; a first shape is etched on the substrate; A micro-channel layer is provided; the micro-channels on the micro-channel layer are respectively a first micro-channel, a second micro-channel, a third micro-channel and a fourth micro-channel; the first micro-channel communicate with the second microfluidic channel through the third microfluidic channel; the fourth microfluidic channel communicates with the first microfluidic channel; the first microfluidic channel and the second microfluidic channel are used for liquid metal and The flow of the solution; the fourth micro-channel is connected to the first micro-channel as a buffer channel, the width of which is slightly larger than that of the third micro-channel; the top of the micro-channel layer is provided with a through hole for liquid metal and injection and outflow of solution; the liquid metal and the first shape together form a deformable electrode. The microfluidic chip provided by the utility model includes deformable microelectrodes based on liquid metal, the shape of the electrodes is controllable, and the distance between the electrodes is adjustable, so the application range is wide and the applicability is strong. Liquid metal electrodes are highly conductive and are not prone to breakdown at high voltages. The preparation method is simple, convenient to use, reusable and low cost.

Description of drawings

1 is a schematic diagram of a microfluidic layer provided for an embodiment of the present utility model;

2 is a schematic structural diagram of a microfluidic chip after alignment and sealing provided by an embodiment of the present invention;

3 is a schematic diagram of the relative positional relationship between the micro-channel and the ITO electrode when the liquid metal is not injected according to the embodiment of the present utility model;

Figure 4 is a schematic diagram of the relative positional relationship between the liquid metal electrode and the ITO electrode when injected at a flow rate of 5 μL/min provided by the embodiment of the present utility model;

5 is a schematic diagram of the relative positional relationship between a slightly deformed liquid metal electrode and an ITO electrode when injected at a flow rate of 6 μL/min provided by the embodiment of the present utility model;

Figure 6 is a schematic diagram of the relative positional relationship between the greatly deformed liquid metal electrode and the ITO electrode when injected at a flow rate of 7 μL/min provided by the embodiment of the present utility model;

Detailed ways

In order to make those skilled in the art better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the specific embodiments.

Glossary:

Liquid metal: Liquid metal refers to an amorphous metal, which can be seen as a mixture of positive ionic fluid and free electron gas. Liquid metal is also an amorphous, flowable liquid metal.

Microfluidic chip: Microfluidic chip technology integrates basic operation units such as sample preparation, reaction, separation, and detection in biological, chemical, and medical analysis processes into a micron-scale chip to automatically complete the entire analysis process. Due to its huge potential in biology, chemistry, medicine and other fields, it has developed into a new research field that intersects with biology, chemistry, medicine, fluids, electronics, materials, machinery and other disciplines.

DEP: Dielectrophoresis (DEP), also known as two-dimensional electrophoresis, is a phenomenon in which an object with a low dielectric constant is subjected to force in a non-uniform electric field. The magnitude of the dielectric force has nothing to do with whether the object is charged or not, and is related to the size, electrical properties of the object, the electrical properties of the surrounding medium, and the field strength, field strength change rate, and frequency of the applied electric field.

DEP buffer: DEP buffer, the main components are as follows, 100ml deionized water, 8.5g sucrose, 0.3g glucose, 0.4mg calcium chloride. This solution has the following functions. First, cells can survive for a long time (isotonicity, more than 4 hours). The function of calcium chloride is to adjust the conductivity. 0.4mg just makes the conductivity of the solution 100us/cm. The amount of this component can be adjusted . Unless otherwise specified, the solutions in this utility model all refer to DEPbuffer.

The utility model provides a microfluidic chip containing deformable liquid metal microelectrodes, comprising:

a substrate; a first shape is etched on the substrate; a micro-channel layer is arranged on the substrate; the micro-channels on the micro-channel layer are respectively a first micro-channel, a second micro-channel, the third micro-channel and the fourth micro-channel; the first micro-channel and the second micro-channel communicate with each other through the third micro-channel; the fourth micro-channel communicates with the first micro-channel; the The first microfluidic channel and the second microfluidic channel are respectively used for the flow of liquid metal and solution; the fourth microfluidic channel and the first microfluidic channel are connected to form a buffer channel, and the width is slightly larger than that of the third microfluidic channel ; A through hole is provided on the top of the micro-channel layer for the injection and outflow of liquid metal and solution; the liquid metal and the first shape together form a deformable electrode.

As shown in FIG. 2 , the substrate 1 provided by the present invention preferably uses ITO glass. ITO conductive glass is made by coating a layer of indium tin oxide (commonly known as ITO) film on the basis of soda-lime-based or silicon-boron-based substrate glass by sputtering, evaporation and other methods. That is, the glass is coated with a layer of indium tin oxide.

Using processes such as photolithography and wet etching technology, the substrate 1 is fabricated into the shape of the electrode 2 of the present invention. That is, a layer of indium tin oxide on the glass is made into the first shape required by the utility model through the soft lithography process and the etching technology. The specific pattern of the first shape can be set according to specific requirements, and does not affect the specific chip effect of the present invention.

Preferably, according to the present utility model, the electrode photolithography and etching process are specifically as follows: in a clean room environment, RJ-304 photoresist is evenly coated on a piece of indium tin oxide (commonly known as ITO) glass at a rotational speed of 3500r/m, and then , put the ITO glass evenly coated with photoresist on the baking table and bake it at 100 degrees for 3 minutes, then put it under the photolithography machine, and expose it through the designed mask at a power of 12.4mJ/ ^cm2 for 1.5 s, then developed for 2 min, dried with nitrogen, then placed in 36% concentrated hydrochloric acid for 3 min, taken out and placed in degumming solution for 2 min, and dried with nitrogen to obtain the electrode.

As shown in FIG. 1 , a first microchannel 5 , a second microchannel 6 , a third microchannel 4 , and a fourth microchannel 7 are fabricated on the microchannel layer by a soft lithography process. The microfluidic layer is preferably made of polydimethylsiloxane (PDMS). PDMS is a kind of organic silicon, because of its low cost, simple use, good adhesion to silicon wafers, and excellent properties. Due to its good chemical inertness and other characteristics, it has become a polymer material widely used in microfluidics and other fields.

According to the present invention, the preparation process of the micro-channel layer is preferably as follows: micro-channel lithography and manufacturing process: evenly coating su-82050 photoresist on the silicon wafer at a rotation speed of 2500r/m in a clean room environment , and then put the evenly coated silicon wafer on the baking table to bake at 65 degrees for 2 minutes and 95 degrees for 7 minutes. Then, put it under the lithography machine, and pass the designed mask at 12.4mJ/cm. ² power exposure for 8s, then develop for 2min, blow dry with nitrogen, and then wrap the silicon wafer around with a board or double-sided tape (encircle the edge of the silicon wafer, which is equivalent to surrounding a glass sheet, and the middle water will not leak). Pour 30g of PDMS (configured by mass 1:10) on the silicon wafer, heat it on a heating plate at 85 degrees for 40 minutes, then remove the silicon wafer, tear off the cured PDMS to obtain a microchannel, and then put the microchannel The outlet inlet of the flow channel is perforated to facilitate the connection of a catheter or needle.

The first microfluidic channel 5 and the second microfluidic channel 6 are connected by a third microfluidic channel 4, and the width of the first microfluidic channel 5 is much larger than that of the third microfluidic channel 4. Width, preferably, the width of the third micro-channel 4 is 80-120 μm. The width of the first micro-channel 5 is more than 1000 μm, and the width of the second micro-channel 6 is 100-200 μm, so that the surface tension of the liquid metal is large enough, when the liquid metal in the first micro-channel 5 is less than 10 μl When flowing at a speed of /min, the liquid metal will deform but will not leak out through the microchannel 4 and enter the second microchannel 6. By controlling the flow rate to 5-10 μl/min, the size of the deformation of the liquid metal can be changed. The micro-channel layer 3 is provided with a through hole 8 , and the liquid metal and DEP buffer flow out and flow in the first micro-channel 5 and the second micro-channel 6 through the through hole 8 .

The function of the fourth microchannel 7 is to act as a buffer when the injection of liquid metal is stopped and then start the injection of liquid metal to prevent the liquid metal from leaking out of the third microchannel 4 into the second microchannel 6 . In order to play a buffering role, the width of the fourth micro-channel 7 needs to be larger than the width of the third micro-channel 4. Preferably, the width of the third micro-channel 4 in the present invention is 100 μm, and the fourth micro-channel 4 7 needs to be 100μm to 200μm, 150μm is the best, by controlling the flow rate to 5-8μL/min, the size of the liquid metal deformation can be changed, thereby changing the gradient of the electric field,

As shown in FIG. 2 , according to the present invention, the substrate 1 is finally placed on the bottom, and the microfluidic layer 3 is placed on the top, and the alignment is performed by the alignment platform, so as to be tightly bonded to prevent liquid leakage.

According to the present invention, the bonding of the electrodes and the microchannels is preferably as follows: placing the electrodes and the microchannels in a plasma cleaning machine for force cleaning for 2 minutes, and after taking them out, align them under a microscope or a lithography machine to ensure the Align the position with the micro-channel, then press and place it on the baking table for 10 minutes at 95 degrees. Remove it, and insert a catheter or needle into the back and forth inlet to obtain the final microfluidic chip.

Figure 3 is an enlarged view of the third microchannel. It should be noted that the width of the electrode 2 is not unique, it can be 50-300 μm, the width of the third microchannel 4 is most preferably 150 μm, and the thickness needs to be less than 20 μm.

The method of the utility model can be used to capture and stretch the cells, and the utility model can repel the polystyrene beads. Not limited to this, the present invention has application potential for more experiments based on the DEP principle.

The following are examples of the utility model:

Example 1

As shown in FIG. 4 , first, the liquid metal was passed into the first microchannel 5 at a flow rate of 5 μL/min and filled the microchannel. When the width of the third micro-channel 4 is less than 150 μm, the flow rate of liquid metal with a flow rate of less than 5 μL/min will not leak from the third micro-channel 4 , and the liquid metal will only flow forward.

Next, the DEP buffer added with red blood cells is passed into the solution microchannel at a speed of 30 μL/min. At this time, the entire first microchannel 5 is liquid metal, the second microchannel 6 is solution, and the third microchannel Lane 4 is also solution.

Then, the microfluidic pump can be turned off to stop feeding the solution, and a sine wave can be passed on both sides of the liquid metal and the electrode. The frequency of the sine wave is 2Mhz and the voltage is 2Vpp. The cells can be captured on the electrode. The edge of the three microchannels 4, increasing the voltage can stretch the red blood cells.

After the experiment, the liquid metal can be recycled from the outlet by introducing air to reduce the cost.

Example 2

As shown in FIG. 5 , firstly, liquid metal was introduced into the first liquid metal microchannel 5 at a flow rate of 6 μL/min to fill the microchannel. When the width of the third micro-channel 4 is 150 μm, the liquid metal flow rate below 8 μL/min will not leak from the liquid metal 4, and the liquid metal forms a protruding shape.

Next, the DEP buffer added with red blood cells is passed into the solution microchannel at a speed of 30 μL/min. At this time, the entire first microchannel 5 is liquid metal, the second microchannel 6 is solution, and the third microchannel Lane 4 is also solution.

Then, the microfluidic pump can be turned off to stop feeding the solution, and a sine wave can be passed on both sides of the liquid metal and the electrode. The frequency of the sine wave is 2Mhz and the voltage is 2Vpp. The cells can be captured on the electrode. The edge of the three microchannels 4, increasing the voltage can stretch the red blood cells.

After the experiment, the liquid metal can be recycled from the outlet by introducing air to reduce the cost.

Example 3

As shown in FIG. 6 , first, liquid metal was introduced into the first liquid metal microchannel 5 at a flow rate of 7 μL/min to fill the microchannel, and when the width of the third microchannel 4 was 150 μm, the liquid metal Forms a more pronounced protruding shape.

Next, the DEP buffer added with red blood cells is passed into the solution microchannel at a speed of 30 μL/min. At this time, the entire first microchannel 5 is liquid metal, the second microchannel 6 is solution, and the third microchannel Channel 4 is also a solution (the tension of water is very small, and there is space to flow in, and the surface tension of liquid metal is very large, so it will not flow, this experiment is based on this principle).

Then, the microfluidic pump can be turned off to stop feeding the solution, and a sine wave can be passed on both sides of the liquid metal and the electrode. The frequency of the sine wave is 2Mhz and the voltage is 2Vpp. The cells can be captured on the electrode, and the capture area is the electrode 2 opposite to 4 edge, increasing the voltage stretches the red blood cells.

After the experiment, the liquid metal can be recycled from the outlet by introducing air to reduce the cost.

The utility model can be used to capture and stretch cells, and the utility model can repel polystyrene beads. Not limited to this, the present invention has application potential for more experiments based on the DEP principle.

Example 4

Capture of yeast cells.

Undeformed electric field gradient is small: a sine wave with a frequency of 1Mhz and a voltage of 2Vpp. Can capture 1, 2 cells

The electric field gradient is large after deformation: a sine wave with a frequency of 1Mhz and a voltage of 2Vpp. Dozens of them can be captured, and the efficiency is increased by dozens of times.

As shown in FIG. 4 , first, the liquid metal microchannel 5 is filled with liquid metal at a flow rate of 5 μL/min. When the width of the third microchannel 4 is 100 μm or less, 5 μL/min or less The liquid metal flow rate will not leak from the third micro-channel 4, and the liquid metal will only flow forward, and then the liquid metal micro-flow pump is turned off to stop injecting the liquid metal.

Next, the DEP buffer with yeast cells was introduced into the solution channel at a speed of 30 μL/min. At this time, the entire first microchannel 5 was liquid metal, the second microchannel 6 was solution, and the third microchannel was filled with liquid metal. The flow channel 4 is also a solution. Because the tension of water is very small, it will flow into it if there is space. The surface tension of the liquid metal is very large, and it will not flow. This experiment is based on this principle.

Then, the solution microfluidic pump can be turned off to stop the introduction of the solution, and a sine wave can be passed on both sides of the liquid metal and the electrode, with a frequency of 1MHz and a voltage of 2Vpp. The yeast cells can be captured on the electrode, and it is found that only 1 or 2 yeast cells are captured. arrive.

Subsequently, the yeast cells were washed away, as shown in Figure 6, and the liquid metal was passed into the liquid metal at a flow rate of 8 μL/min, the electrode would be deformed, resulting in a larger electric field gradient, close the liquid metal microfluidic pump, open the solution microfluidic pump, and pass Enter the yeast cells, and at the same time pass a sine wave on both sides of the liquid metal and the electrode, the frequency is 1MHz, and the voltage is 2Vpp, the yeast cells can be captured on the electrode, and it is found that dozens of yeast cells are captured.

After the experiment, the liquid metal can be recycled from the outlet by introducing air to reduce the cost.

From the above embodiment, it can be seen that the method and electrode provided by the present invention will significantly improve the versatility and breadth of the microfluidic chip. In one experiment, the flow rate increases from 5 to 10, and the deformation gradually increases, or Different flow rates were passed through in different experiments, resulting in electrodes with different deformations.

The above are only the preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be regarded as limitations of the present invention, and the protection scope of the present invention should be based on the scope defined by the claims. For those skilled in the art, without departing from the spirit and scope of the present invention, several improvements and modifications can also be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims (5)

1. A microfluidic chip comprising a deformable liquid metal electrode, comprising:

a substrate; etching a first shape on the substrate;

a micro-channel layer is arranged on the substrate; the micro-channels on the micro-channel layer are respectively a first micro-channel, a second micro-channel, a third micro-channel and a fourth micro-channel; the first micro-channel is communicated with the second micro-channel through a third micro-channel; the fourth micro-channel is communicated with the first micro-channel;

the first micro-channel and the second micro-channel are respectively used for flowing liquid metal and solution; the fourth micro-channel is communicated with the first micro-channel to form a buffer channel, and the width of the buffer channel is slightly larger than that of the third micro-channel;

the top of the micro-flow channel layer is provided with a through hole for injecting and flowing out liquid metal and solution;

the liquid metal and the first shape together form a deformable electrode.

2. The chip of claim 1, wherein the micro channel layer is made of Polydimethylsiloxane (PDMS).

3. The chip of claim 1, wherein the substrate is ITO conductive glass.

4. The die of claim 1, wherein the liquid metal deformable electrode is formed by varying a liquid metal injection speed.

5. The chip of claim 1, wherein the first micro-channel has a width of 1000 μm, the second micro-channel has a width of 100-.

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