CN106656139B - A kind of RF switch device and preparation method thereof based on electrowetting driving principle - Google Patents

Abstract

The invention discloses a radio frequency switch device based on an electrowetting driving principle and a preparation method thereof. The device comprises: a lower electrode plate, an upper electrode plate, and droplets placed between the lower electrode plate and the upper electrode plate. Wherein, the lower electrode plate includes: a first substrate, a driving electrode layer, a dielectric layer, a radio frequency electrode layer and a first hydrophobic layer arranged in sequence. The upper electrode plate includes: a second substrate, a ground electrode and a second hydrophobic layer arranged in sequence. The droplets are placed between the first hydrophobic layer and the second hydrophobic layer. The radio frequency switch device of the present invention controls the on-off of the radio frequency circuit by driving the aqueous solution to move to different positions, has the characteristics of simple control and high degree of automation, and greatly expands the application scope of technologies such as microfluidic control and radio frequency switch.

Description

A kind of radio frequency switch device based on electrowetting driving principle and preparation method thereof

technical field

The invention belongs to the field of radio frequency circuits and switches, relates to a microfluidic technology based on electrowetting principle and the absorption effect of liquid on high-frequency electromagnetic field energy, and in particular relates to a radio frequency switch device based on electrowetting driving principle and a preparation method thereof.

Background technique

In recent years, RF circuits have developed rapidly in fields such as the Internet of Things and communication systems. RF switches have also attracted much attention as control components of RF circuits. Commonly used RF switches mainly include transistor switches and micromechanical switches. Although transistor switches have fast switching speed, they have disadvantages such as large on-resistance, low off-resistance, and low applicable power; while micro-mechanical switches have better performance than resistance switches, but have slow switching speeds, large mechanical losses, and large contact resistance. Lamp shortcomings.

The idea of using liquid metal to fabricate RF switches has recently attracted widespread attention. However, liquid metals such as mercury and indium-gallium alloys have problems such as high toxicity, easy oxidation, and poor material compatibility. For this reason, the use of liquid materials such as aqueous solutions to make RF switches becomes extremely meaningful.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a radio frequency switch device based on the electrowetting driving principle and a preparation method thereof, which solves the problems of the conventional diode switch or micro-mechanical switch such as difficulty in preparation, wear and tear, etc. The electrowetting effect controls the position of the droplet, which in turn controls the on and off of the radio frequency circuit.

In order to achieve the above object, the present invention provides a radio frequency switch device based on the electrowetting driving principle, the device comprising: a lower electrode plate, an upper electrode plate, a liquid liquid placed between the lower electrode plate and the upper electrode plate drop.

Wherein, the lower electrode plate comprises: a first substrate, a driving electrode layer, a dielectric layer, a radio frequency electrode layer and a first hydrophobic layer arranged in sequence.

Wherein, the upper electrode plate comprises: a second substrate, a ground electrode and a second hydrophobic layer arranged in sequence.

Wherein, the droplets are placed between the first hydrophobic layer and the second hydrophobic layer.

The drive electrode layer includes: n electrically isolated drive electrodes; the radio frequency electrode layer includes m electrically isolated radio frequency electrodes; m and n are natural numbers, n≥2, m≥1, n≥m.

When the droplet is directly above any RF electrode, the RF electrode is in a disconnected state; when the droplet is not directly above a certain RF electrode, the RF electrode is in a conductive state.

Both the first substrate and the second substrate are made of insulating materials.

The dielectric layer is a high dielectric constant material, and the high dielectric constant material includes any one or more than two of CEP, SU-8 and tantalum pentoxide.

Both the first hydrophobic layer and the second hydrophobic layer are made of hydrophobic materials, and the hydrophobic materials include: any one or two of Teflon and fluororesin.

The ground electrode is made of conductive transparent material.

The droplets are polar molecular solutions.

The droplets include: any one or two or more of water, aqueous solution, and ethanol.

The present invention also provides a preparation method of the radio frequency switch device based on the electrowetting driving principle, the method comprising:

Step 1: preparing the lower plate: forming a thin film on the surface of the first substrate, forming a driving electrode layer by photolithography etching or stripping, and then preparing a dielectric layer, a radio frequency electrode layer and a first hydrophobic layer in sequence;

Step 2, preparing the upper plate: forming a thin film on the surface of the second substrate, forming a ground electrode by photolithography etching or stripping, and then preparing a second hydrophobic layer on the ground electrode;

In step 3, the droplet is placed above the driving electrode, and the upper electrode plate and the lower electrode plate are assembled to form the radio frequency switching device based on the electrowetting driving principle.

The radio frequency switch device based on the electrowetting driving principle and the preparation method thereof provided by the present invention solve the problems of the conventional diode switch or micromechanical switch, such as the difficulty in preparation, wear and tear, and the like, and have the following advantages:

(1) The present invention replaces liquid metals such as mercury or indium gallium alloy with an aqueous solution, etc., and uses the aqueous solution to absorb electromagnetic waves to make the radio frequency switch device work, which overcomes the disadvantages of high toxicity and easy oxidation;

(2) The solution of the present invention does not need to be in direct contact with the radio frequency electrode to absorb electromagnetic energy, thereby avoiding electrochemical by-products or pollution;

(3) The present invention controls the switching effect by designing the driving electrode, the radio frequency electrode and the relative positions of the two, which is simple and easy to implement.

Description of drawings

FIG. 1 is a cross-sectional view of a radio frequency switching device based on the electrowetting driving principle of the present invention.

FIG. 2 is a top view of the radio frequency switching device based on the electrowetting driving principle of the present invention.

Detailed ways

The technical solutions of the present invention will be further described below with reference to the accompanying drawings and embodiments.

As shown in FIG. 1, it is a cross-sectional view of a radio frequency switch device based on the electrowetting driving principle of the present invention. The device includes: a lower electrode plate 100 and an upper electrode plate 200, which are placed on the lower electrode plate 100 and the upper electrode plate. Droplet D between 200.

The lower electrode plate 100 includes: a first substrate 105 , a driving electrode layer 104 , a dielectric layer 103 , a radio frequency electrode layer 102 and a first hydrophobic layer 101 , which are arranged in sequence.

The upper plate 200 includes: a second substrate 203 , a ground electrode 202 and a second hydrophobic layer 201 arranged in sequence.

The droplet D is placed between the first hydrophobic layer 101 and the second hydrophobic layer 201 . Droplet D refers to a droplet that can be driven by the principle of electrowetting, which is a polar molecular solution, and the polar molecular solution includes (but is not limited to): any one or two or more of water, aqueous solution or ethanol , the droplet D should ensure its absorption effect on high-frequency electromagnetic energy.

The drive electrode layer 104 includes: n electrically isolated drive electrodes; the radio frequency electrode layer (102) includes m electrically isolated radio frequency electrodes; m and n are natural numbers, n≥2, m≥1, n≥m. Preferably, the radio frequency electrode layer 102 is electrically isolated by the dielectric layer 103 .

The number of the above-mentioned driving electrodes and RF electrodes is not necessarily the same, each RF electrode corresponds to one driving electrode, and the number of driving electrodes is not less than the number of RF electrodes, and there is at least one RF electrode. When there is one RF electrode, at least two driving electrodes are required to realize the two states of off and on. When the number m of RF electrodes is greater than 1, the number of driving electrodes is also m if all the RF electrodes are not considered on; if all the RF electrodes are considered on, there should be at least one driving electrode that does not correspond to the RF electrodes , when the droplet is located above the electrode, none of the RF electrodes is covered by the droplet, and this quantitative relationship can be shown in Figure 2.

The above-mentioned radio frequency electrodes are any one or two or more of the antennas, wires or electrodes in the radio frequency circuit. When the droplet D is directly above any RF electrode, the RF electrode is in an off state; when the droplet D is not directly above a certain RF electrode, the RF electrode is in an on state. When the droplet D is above a certain RF electrode, the polar molecules inside it vibrate under the action of the high-frequency electromagnetic field, absorbing a large amount of electromagnetic field energy and converting it into the internal energy of the system, thereby making the RF electrode below the droplet D. The electromagnetic signal transmitted in the device is greatly attenuated to achieve the effect of disconnection.

The above-mentioned driving electrodes and radio frequency electrodes may be planar electrodes or three-dimensional electrodes, depending on the criteria for realizing their functions.

Both the first substrate 105 and the second substrate 203 are made of insulating materials. The material used as the substrate is not fixed as long as it is insulating.

The dielectric layer 103 is made of a non-conductive material with a certain dielectric constant and breakdown resistance. Preferably, the dielectric layer 103 is made of a material with high dielectric constant and strong breakdown resistance. More preferably, the high dielectric constant material includes: CEP (traditional cycloaliphatic epoxy resin), any one or two or more of SU-8 and tantalum pentoxide. SU-8 is a negative-tone, epoxy-based, near-UV photoresist.

Both the first hydrophobic layer 101 and the second hydrophobic layer 201 are made of hydrophobic materials. Preferably, the hydrophobic material is a material that can reduce the surface tension of the droplets. More preferably, the hydrophobic material includes: Teflon, fluororesin any one or both.

The ground electrode 202 is also used as a driving electrode. In principle, the ground electrode 202 and the driving electrodes on the driving electrode layer 104 can be composed of any conductive material, but in order to simplify the chip fabrication process, preferably, the same material as the radio frequency electrode is used.

In order to expand the function integration of the chip, preferably, the ground electrode 202 is made of a conductive transparent material, and the conductive transparent material includes any one or two or more of indium tin oxide (ITO) and aluminum-doped zinc oxide (AZO).

The size, interval and number of all electrodes of the present invention are not limited. This specification only uses electrodes with a certain number and specifications as an example; the drawings in the description are only schematic diagrams, and do not accurately reflect the position and arrangement of electrodes.

The working principle of the radio frequency switch device of the present invention is as follows:

As shown in FIG. 2 , which is a top view of the RF switching device based on the electrowetting driving principle of the present invention, the first RF electrode 1021 and the second RF electrode 1021 and the second RF electrode are respectively above the first driving electrode 1041 and the second driving electrode 1043 . The electrode 1022, the driving electrode layer and the radio frequency electrode layer are separated by the dielectric layer 103.

When a voltage is applied to the third driving electrode 1042 and the first driving electrode 1041 and the second driving electrode 1043 are grounded, the droplet D is driven to the top of the third driving electrode 1042 under the action of electrowetting. One radio frequency electrode 1021 and the second radio frequency electrode 1022 are in a conducting state.

When a voltage is applied to the first driving electrode 1041, and the third driving electrode 1042 and the second driving electrode 1043 are grounded, the droplet D is driven to the top of the first driving electrode 1041 under the action of electrowetting, and the first The radio frequency electrode 1021 is in an off state, and the second radio frequency electrode 1022 is in an on state.

When a voltage is applied to the second driving electrode 1043 and the first driving electrode 1041 and the third driving electrode 1042 are grounded, the droplet D is driven to the top of the second driving electrode 1043 under the action of electrowetting, and the second The radio frequency electrode 1022 is in an off state, while the first radio frequency electrode 1021 is in an on state.

When a voltage is applied to the first driving electrode 1041 and the second driving electrode 1043, and the third driving electrode 1042 is grounded, the droplet D is driven to the first driving electrode 1041 and the second driving electrode 1041 under the action of electrowetting. Above the electrode 1043, the first radio frequency electrode 1021 and the second radio frequency electrode 1022 are both disconnected. At this time, the droplet D has two situations, as follows:

The first case: the third driving electrode 1042 and the droplet D are large enough, at this time, the middle of the droplet D contracts and extends on both sides, covering the first driving electrode 1041 and the second driving electrode 1043 at the same time, and the droplet D deforms into Dumbbell-shaped without breaking;

The second case: the third driving electrode 1042 and the droplet D are relatively small, then the first driving electrode 1041 and the second driving electrode 1043 apply a pulling force to the two sides of the droplet D through electrowetting, so that the It is broken into two droplets, which are located on the surfaces of the first driving electrode 1041 and the second driving electrode 1043 respectively.

The above is only a principle description of the present invention, and it is allowed to improve and expand the structure and use of the device without affecting its functionality.

The above-mentioned applied voltage means that when the droplet manipulation is performed, the voltage of the corresponding electrode is set to be non-zero so that the electrowetting driving can occur. The above grounding means that the voltage of the corresponding electrode is set to 0 or close enough to 0 when the droplet manipulation is performed. The above-mentioned conduction of the radio frequency electrode means that the corresponding radio frequency electrode can transmit the electrical signal from one end to the other end with low loss. The above-mentioned disconnection of the radio frequency electrode means that the corresponding radio frequency electrode cannot transmit the electrical signal from one end to the other end, or the transmission loss is so great that the back end cannot receive it effectively.

The invention also provides a preparation method of a radio frequency switch device based on the electrowetting driving principle and the absorption effect of the aqueous solution on electromagnetic waves, the method comprising:

Step 1: Prepare the lower plate 100: form a thin film on the surface of the first substrate 105, form the driving electrode layer 104 by photolithography etching or peeling, and then prepare the dielectric layer 103, the radio frequency electrode layer 102 and the first hydrophobic layer in sequence 101;

Step 2, preparing the upper plate 200: forming a thin film on the surface of the second substrate 203 to obtain the ground electrode 202, and then preparing the second hydrophobic layer 201 on the ground electrode 202;

In step 3, the droplet D is placed above the driving electrode, and the upper electrode plate 100 and the lower electrode plate 200 are assembled to form the radio frequency switching device based on the electrowetting driving principle.

In step 1, the thin film formed on the surface of the first substrate 105 is a metal thin film, which is prepared by using processes such as spin coating, evaporation, and sputtering; the dielectric layer 103 and the first hydrophobic layer 101 are both prepared by spin coating and physical sputtering. , chemical vapor deposition, evaporation and other methods; the radio frequency electrode layer 102 is first prepared by spin coating, evaporation, sputtering film formation and other methods to prepare a metal thin film, and then obtained by photolithography etching or stripping.

In step 2, the thin film formed on the surface of the second substrate 203 is a metal thin film, which is prepared by processes such as spin coating, evaporation, and sputtering; the second hydrophobic layer 201 is prepared by methods such as spin coating and sputtering.

After the radio frequency switching device based on the electrowetting driving principle of the present invention is combined with other microfluidic and radio frequency devices, the digital microfluidic operation method can automatically realize the switching and manipulation of the radio frequency circuit.

To sum up, the present invention provides a radio frequency switch device based on the electrowetting driving principle and a preparation method thereof. The device adopts an aqueous solution to reduce toxicity, and controls the position of the droplet through the electrowetting effect, thereby controlling the conduction of the radio frequency circuit. It has the characteristics of novel design, simple control and high degree of automation, which greatly expands the application scope of microfluidic and radio frequency switching technologies.

While the content of the present invention has been described in detail by way of the above preferred embodiments, it should be appreciated that the above description should not be construed as limiting the present invention. Various modifications and alternatives to the present invention will be apparent to those skilled in the art upon reading the foregoing. Accordingly, the scope of protection of the present invention should be defined by the appended claims.

Claims (8)

1. a kind of RF switch device based on electrowetting driving principle, which is characterized in that the device includes:

Bottom crown (100),

Top crown (200),

The drop (D) being placed between the bottom crown (100) and top crown (200)；

The bottom crown (100) includes: the first substrate (105) for setting gradually, drive electrode layer (104), dielectric layer (103), radio-frequency electrode layer (102) and the first hydrophobic layer (101)；

The top crown (200) includes: the second substrate (203), grounding electrode (202) and the second hydrophobic layer set gradually (201)；

The drop (D) is placed between the first hydrophobic layer (101) and the second hydrophobic layer (201)；

The drive electrode layer (104) includes: the driving electrodes of n electrical isolation；The radio-frequency electrode layer (102) includes The radio-frequency electrode of m electrical isolation；M and n is natural number, n >=2, m >=1, n >=m；

When the drop (D) is in right above any one radio-frequency electrode, which is in an off state；When described Drop (D) when being not in right above some radio-frequency electrode, the radio-frequency electrode is in the conductive state.

2. the RF switch device as described in claim 1 based on electrowetting driving principle, which is characterized in that described first Substrate (105) and the second substrate (203) are all made of insulating materials.

3. the RF switch device as described in claim 1 based on electrowetting driving principle, which is characterized in that the medium Layer (103) is high dielectric constant material, which includes: any one in CEP, SU-8 and tantalum pentoxide Or it is two or more.

4. the RF switch device as described in claim 1 based on electrowetting driving principle, which is characterized in that described first Hydrophobic layer (101) and the second hydrophobic layer (201) are all made of hydrophobic material, which includes: appointing in Teflon, fluororesin Meaning is one or two kinds of.

5. the RF switch device as described in claim 1 based on electrowetting driving principle, which is characterized in that the ground connection Electrode (202) uses conductive transparent material.

6. the RF switch device as described in claim 1 based on electrowetting driving principle, which is characterized in that the drop It (D) is polar molecule solution.

7. the RF switch device as described in claim 1 based on electrowetting driving principle, which is characterized in that the drop (D) include: water, aqueous solution, in ethyl alcohol any one or it is two or more.

8. a kind of preparation of the RF switch device based on electrowetting driving principle as described in any one of claim 1-7 Method, which is characterized in that this method includes:

Step 1: preparing bottom crown (100): forming film on the first substrate (105) surface, pass through chemical wet etching or the side of removing Method forms drive electrode layer (104), then is sequentially prepared dielectric layer (103), radio-frequency electrode layer (102) and the first hydrophobic layer (101)；

Step 2, top crown (200) are prepared: forming film on the second substrate (203) surface and obtains grounding electrode (202), then connecing The second hydrophobic layer (201) are prepared on ground electrode (202)；

Step 3, drop (D) is placed on above driving electrodes, top crown (100), bottom crown (200) assembling is formed described RF switch device based on electrowetting driving principle.