Digital micro-fluidic chip using super-hydrophobic nanoparticles as hydrophobic layer

Abstract

A digital micro-fluidic chip using super-hydrophobic nanoparticles as a hydrophobic layer relates to the field of micro-fluidic chips, and comprises a lower polar plate, or an upper polar plate and a lower polar plate; the lower pole plate comprises a substrate, an electrode array, a dielectric layer and a hydrophobic layer which are arranged from bottom to top; the upper electrode plate comprises ITO glass and a hydrophobic layer which are arranged from top to bottom; the hydrophobic layer is made of a super-hydrophobic nano particle material, and the hydrophobic angle of the hydrophobic layer is 145-150 degrees. According to the invention, a uniform and stable hydrophobic coating can be formed on the surfaces of a plurality of substrates such as a PCB substrate, glass and the like by adopting simple methods such as solution brushing, dipping, spraying and the like. The hydrophobic layer of the super-hydrophobic nano material is cheaper, the manufacturing cost of the digital micro-fluidic chip is effectively reduced, and meanwhile, the performance and the application range of the digital micro-fluidic chip are widened.

Description

Technical Field

[0001] The invention relates to the field of microfluidic chips, and in particular to a digital microfluidic chip using super-hydrophobic nanoparticles as a hydrophobic layer. Background Art

[0002] Digital microfluidics (DMF) is an emerging advanced manufacturing technology that mainly achieves the purpose of liquid manipulation and analysis through precise control of independent tiny droplets or liquid columns. Common driving methods include dielectric wetting, which uses the dielectric wetting principle of droplets on hydrophobic surfaces to control the change of the droplet contact angle on the electrode array to achieve precise control of discrete droplets. Compared with traditional microfluidic chips, DMF not only retains the characteristics of low sample consumption, precise control and fast analysis speed, but also eliminates the need for components such as micropumps and microvalves, and has the advantages of simple structure and dynamic configuration. Therefore, digital microfluidic systems are particularly suitable for biological and chemical micro-total analysis systems that require high integration and high performance.

[0003] Digital microfluidic chips are mainly composed of four parts: substrate, electrode, dielectric layer and hydrophobic layer. The hydrophobic layer is usually located on the entire chip surface, which makes the droplets have a higher contact angle on the chip surface, reduces the wettability of the liquid and the solid surface, helps to control the shape and movement of the liquid interface, and precisely manipulate the droplets.

[0004] Common hydrophobic materials include silane compounds or fluorinated polymers. Representative materials of silane compounds are trichlorosilane (SiCl3) and various organosilanes. Such materials can form a uniform and dense hydrophobic monolayer by chemical deposition or self-assembly. However, the chemical stability and durability of such materials are relatively poor, and the requirements for preparation conditions are relatively strict. Fluorinated polymers such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF) have strong hydrophobicity, and the preparation process is relatively simple, and the chemical resistance and temperature resistance are good, but their surface roughness is high and the adhesion to the substrate is weak, which is not conducive to the fine control of the fluid. Summary of the invention

[0005] The purpose of the present invention is to solve the above problems existing in the prior art and to provide a digital microfluidic chip using super-hydrophobic nanoparticles as a hydrophobic layer.

[0006] In order to achieve the above object, the present invention adopts the following technical scheme:

[0007] A digital microfluidic chip using super-hydrophobic nanoparticles as a hydrophobic layer comprises a lower electrode plate, or an upper electrode plate and a lower electrode plate; the lower electrode plate comprises a substrate, an electrode array, a dielectric layer and a hydrophobic layer arranged from bottom to top; the upper electrode plate comprises ITO glass and a hydrophobic layer arranged from top to bottom; the hydrophobic layer is composed of a super-hydrophobic nanoparticle material, and the hydrophobic angle of the hydrophobic layer is 145° to 150°.

[0008] The super-hydrophobic nano-particle material comprises silicon dioxide nano-particles prepared by a sol-gel method.

[0009] The super hydrophobic nanoparticle material is formed into the hydrophobic layer by means of solution brushing, solution dipping or solution spraying on the dielectric layer.

[0010] The solution is sprayed 2 to 5 times.

[0011] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0012] 1. The present invention uses super-hydrophobic nanomaterial silicon dioxide nanoparticles to prepare a hydrophobic layer. Its suitable rough surface structure can effectively reduce the contact area between the liquid and the solid surface, greatly increase the contact angle of the droplet, and achieve a super-hydrophobic effect of 145°~150°. This extremely strong hydrophobic property greatly reduces the adhesion between the droplet and the surface, which is conducive to the rapid movement and precise control of the droplet on the digital microfluidic chip.

[0013] 2. The hydrophobic layer of the super-hydrophobic nanomaterial of the present invention can be coated uniformly and stably on different substrates such as the PCB substrate and glass of the digital microfluidic chip by various methods such as brushing, dipping, and spraying. Compared with other materials that are baked at high temperature to form a film, this material can be baked at 60-80°C or dried at room temperature to form a stable film. The preparation process is simple and controllable, environmentally friendly, and low in cost.

[0014] 3. The present invention uses silicon dioxide nanoparticles as super-hydrophobic nanomaterials to prepare the hydrophobic layer, which has good chemical stability and high temperature resistance, and can significantly extend the service life of the digital microfluidic chip. Moreover, this super-hydrophobic nanomaterial hydrophobic layer is not only cheaper, but also effectively reduces the manufacturing cost of the digital microfluidic chip, while broadening its performance and application range. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a structural schematic diagram of the present invention.

[0016] Figure 2 This is a schematic diagram of the structure of Example 2.

[0017] Figure 3 The test results of droplet driving performance of DMF chip with hydrophobic layer sprayed at different times.

[0018] Figure 4 The hydrophobicity results of the lower plate obtained after different spraying times. DETAILED DESCRIPTION

[0019] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer and more understandable, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0020] The super-hydrophobic nanoparticle material of the present invention is prepared by a sol-gel method: a high-purity silicate (metal alkoxide or inorganic salt) is selected as a precursor of silicon dioxide, and an appropriate amount of catalyst (sodium hydroxide or hydrochloric acid) and an ethanol solvent, as well as deionized water are added to adjust the pH value and concentration of the reaction system. The above raw materials are stirred on a magnetic stirrer to ensure that the raw materials are evenly mixed. Under appropriate temperature and pH conditions, hydrolysis and condensation chemical reactions are carried out to form a stable transparent sol system in the solution. After aging of the sol, the colloid particles slowly polymerize to form a gel with a three-dimensional spatial network structure. The gel network is filled with a solvent that has lost its fluidity, and then the organic components are removed by drying and roasting, and finally a substantially transparent super-hydrophobic nanoparticle material is obtained.

[0021] The super hydrophobic nanoparticle material is formed into the hydrophobic layer by means of solution brushing, solution dipping or solution spraying on the dielectric layer.

[0022] Example 1

[0023] Figure 1 A digital microfluidic chip in the form of a bipolar plate on a PCB substrate is provided, comprising an upper electrode plate and a lower electrode plate which are parallel and opposite to each other;

[0024] The lower plate includes a PCB substrate 2, an electrode array 1, a dielectric layer 3 and a hydrophobic layer 4 from bottom to top, and the upper plate includes an ITO glass 6 and a hydrophobic layer 4 from top to bottom, and a droplet 5 moves between the upper plate and the lower plate. The electrode array is formed by a chemical deposition metal method. The dielectric layer is made of materials such as SU-8, Parylene C, Al2O3-PET, etc.

[0025] Example 2

[0026] Figure 2 A digital microfluidic chip in the form of a monopolar plate with a PCB substrate is provided. The lower electrode plate includes a PCB substrate 2, an electrode array 1, a dielectric layer 3 and a hydrophobic layer 4 from bottom to top, and a droplet 5 moves on the surface of the lower electrode plate.

[0027] Example 3

[0028] A volume of 5 μL of deionized water was added to the digital microfluidic chip prepared in Example 1 as a test droplet, and the droplet was driven to move back and forth with a voltage of 180 V; a camera was used to record and analyze the movement rate of the droplet. Figure 3 The movement rate of the droplets can be controlled by the number of spraying times.

[0029] Example 4

[0030] The hydrophobicity of the hydrophobic layer on the lower electrode prepared in Example 1 was investigated, and the contact angle of 5 μL of deionized water when the droplet was powered (voltage amplitude was 180 V) was recorded using ImageJ. Figure 4 The number of spraying times is related to the hydrophobic angle of the droplets. When the number of spraying times is 2, the hydrophobic angle of the droplets can reach about 145°.

Claims

1. A digital microfluidic chip using super-hydrophobic nanoparticles as a hydrophobic layer, characterized in that: It includes a lower electrode plate, or an upper electrode plate and a lower electrode plate; the lower electrode plate includes a substrate, an electrode array, a dielectric layer and a hydrophobic layer arranged from bottom to top; the upper electrode plate includes ITO glass and a hydrophobic layer arranged from top to bottom; the hydrophobic layer is composed of super-hydrophobic nanoparticle material, and the hydrophobic angle of the hydrophobic layer is 145°~150°.

2. A digital microfluidic chip using super-hydrophobic nanoparticles as a hydrophobic layer as claimed in claim 1, characterized in that: The super-hydrophobic nano-particle material comprises silicon dioxide nano-particles prepared by a sol-gel method.

3. A digital microfluidic chip using super-hydrophobic nanoparticles as a hydrophobic layer as claimed in claim 1 or 2, characterized in that: The super hydrophobic nanoparticle material is formed into the hydrophobic layer by means of solution brushing, solution dipping or solution spraying on the dielectric layer.

4. A digital microfluidic chip using super-hydrophobic nanoparticles as a hydrophobic layer as claimed in claim 3, characterized in that: The solution is sprayed 2 to 5 times.

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