CN102627255A - Micro-nano integrated processing technology based implantable three-dimensional anti-drag micro-channel and preparation method thereof - Google Patents

Abstract

An implantable three-dimensional drag-reducing microfluidic channel and its preparation method based on micro-nano integrated processing technology, using the maskless optimized deep reactive ion etching (DRIE) process, directly on the surface of silicon-based micron-scale grooves to achieve high Density and high aspect ratio nano-forest structure, and then use the casting method to transfer the silicon-based micro-scale grooves and the nano-forest structure on the surface to PDMS, and then use the DRIE post-treatment process to treat the surface of PDMS physically and chemically to reduce the surface energy. A PDMS three-dimensional drag-reducing microchannel with superhydrophobic properties is realized. The present invention can greatly increase its area-to-volume ratio and reduce surface energy, so that the surface of the microfluidic channel has superhydrophobic properties, achieving excellent drag reduction effects, and can further improve its stable superhydrophobic properties, thereby greatly improving its drag reduction effect, and the process is simple, the cost is low, and the industrialization is easy.

Description

Implantable three-dimensional drag-reducing microchannel and preparation method based on micro-nano integrated processing technology

technical field

The invention relates to the technical field of micromachining, in particular to an implantable three-dimensional drag-reducing microfluidic channel based on micro-nano integrated processing technology and a preparation method thereof.

Background technique

Since its appearance in the 1980s, microelectromechanical system (MEMS), as an emerging, high-tech multi-field interdisciplinary subject, has been hailed as a new technological revolution leading the development of the microelectronics industry in the new century, and has been favored by domestic Widespread attention. Among them, Bio-medical MEMS, as one of the most important branches of MEMS, has been closely watched by scientific research institutions and industries, among which the most eye-catching is the micro total analysis system (micro total analysis system, That is, μTAS) is also called Lab-on-a-chip (Lab-on-a-chip). It is a complete microsystem that integrates the three steps of sample preparation, biochemical reaction and result detection on a single device and can perform specific analysis functions. It can be divided into two categories: chip type and non-chip type. At present, its development focuses on chip-type micro-analysis systems, including two types of microarray chips (Microarray Chip) and microfluidic chips (Microfluidic chip), which have the advantages of low sample detection threshold, high sensitivity, fast analysis speed, and low cost. Industrialization has been realized, and there are thousands of enterprises producing biochips.

The core of the chip-type micro-analysis system is to use micro-processing technology to prepare groove structures on the substrate, based on analytical chemistry and analytical biochemistry, to realize real-time detection, analysis and processing of biological samples. The characteristic size of the groove structure is usually tens to hundreds of microns. Unlike the grooves on the macro scale, due to the influence of the size effect, when the fluid flows in the groove structure of the micro-nano scale, its viscous resistance becomes very Huge, which makes liquid flow extremely difficult. According to Poiseuille's law, the pressure difference required by the channel is inversely proportional to the fourth power of the size, which means that the drive of microfluidics requires a large external driving force and corresponding driving device (usually requires It can only flow smoothly with the help of external driving force), such as micro pumps, micro valves and micro energy sources, etc., which brings a series of disadvantages, such as complex structure, low system stability, high power consumption, and difficulty in miniaturization. Therefore, realizing a microchannel with a drag-reducing effect is one of the key scientific problems to be solved urgently in the field of micro-total analysis system research.

Due to the particularity of the needs in the biomedical field, implantable drag-reducing microchannels have become the top priority in the research of micro-total analysis systems, and the most common material is polydimethylsiloxane (Polydimethylsiloxane, abbreviated as for PDMS). It is a high-molecular organosilicon compound, also known as organosilicon, which has the characteristics of low cost, non-toxic, non-flammable, good biocompatibility, and excellent light transmission. Therefore, in the field of micro-nano processing technology, especially Microfluidics, biomedical microsystems and other fields are widely used. Although the PDMS material itself is hydrophobic (the contact angle is about 105°-120°), at the microscopic scale, its viscous resistance is very large due to the significant enhancement of the laminar flow effect, surface force, and capillary effect.

In the past decade, many technologies have been developed to realize structured surfaces with drag reduction effects, including polymer drag reducers, drag-reducing coatings, biomimetic structure replication, and micro-nano dual-scale particle modification technologies. Polymer drag reducing agent and drag reducing coating [Example: Choi K S, Appl Sci Res, 1989, 46: 209-216] is the most widely used class, and its process method is simple, but this injection of polymer drag reducing The drag reducing agent or the method of coating the drag reducing coating to form the drag reducing interface, the waste of the drag reducing agent is serious, and the service life is seriously insufficient.

Biomimetic structure replication [Example: Bechert D W, AIAA Shear Flow Control Conference, 1985] is to repeat the natural surface structure with drag reduction effect through micro-processing technology, but its drag reduction efficiency is low. In recent years, researchers have proposed a drag-reducing channel design based on surface modification of micro-nano dual-scale particles [Example: Lu Si, Chinese Science: Series G, 2010, 40: 916-924], which can achieve high-efficiency drag-reducing effects, However, the realization of the above-mentioned micro-nano dual-scale particle structure usually requires multi-step complex processes and high cost. More importantly, it is difficult to realize the drag-reducing structure on the sidewall and top surface of the groove, that is, it is impossible to realize the real three-dimensional drag-reducing microstructure. runner.

Contents of the invention

In order to overcome the deficiencies of the prior art structures, the present invention provides an implantable three-dimensional drag-reducing microchannel and a preparation method based on micro-nano integrated processing technology.

The purpose of the present invention is to propose an implantable three-dimensional drag-reducing microfluidic channel and its preparation method based on micro-nano integrated processing technology, which utilizes the maskless optimized deep reactive ion etching (DRIE) Surface preparation realizes high-density and high-aspect-ratio nano-forest structure, and then uses the casting method to transfer micron-scale grooves and the nano-forest structure on the surface to PDMS, and then uses DRIE post-treatment process to treat the surface of PDMS physically and chemically to reduce the surface energy. , so as to realize the PDMS three-dimensional drag-reducing microchannel with super-hydrophobic properties. The preparation method is simple in process, low in cost, high in drag-reducing efficiency, and more importantly, has implantability.

To achieve the above purpose, the present invention provides an implantable three-dimensional drag-reducing microfluidic channel structure based on micro-nano integrated processing technology, the structure includes: PDMS substrate, PDMS cover plate, micro-grooves, and nano-mesh array.

The thickness of PDMS substrate and PDMS cover plate is 50μm-1000μm;

The PDMS cover plate is bonded on the PDMS substrate;

The micro-groove is made on the PDMS substrate, and the closed cavity is formed by the PDMS substrate and the PDMS cover plate. The cross section is an inverted triangle, inverted trapezoid or semicircle, and its characteristic size is 10 μm-1000 μm;

The nano-sieve array is made on the surface of the micro-groove, and is a sieve with a diameter of 10nm-1000nm, a depth of 10nm-5000nm, and a spacing of 10nm-1000nm.

The present invention also provides a method for preparing an implantable three-dimensional drag-reducing microchannel based on micro-nano integrated processing technology, the method comprising:

Step 1: By combining photolithography and chemical or physical etching, fabricate a micron trench mold on a silicon substrate with a triangular or trapezoidal or semicircular cross-section;

Step 2: Utilize the maskless optimized deep reactive ion etching process to fabricate high-density and high aspect ratio nano-forests directly on silicon-based micro-groove molds and smooth silicon wafer surfaces;

Step 3: Utilize the PDMS molding process, adjust the process parameters, and use the silicon-based micro-groove mold and nano-forest as a template to realize a PDMS cover plate with a nano-mesh array, a PDMS substrate, and a micro-groove;

Step 4: Use the DRIE post-treatment process to adjust the parameters to perform physical and chemical treatments on the PDMS cover plate and the PDMS substrate, wherein the PDMS substrate contains micron grooves to reduce its surface energy and improve its stable superhydrophobic properties;

Step 5: Bond the PDMS substrate and the PDMS cover plate by high-temperature bonding or physical pressure at room temperature to form a closed microchannel.

In the above scheme, the maskless optimization deep reactive ion etching process described in step 2 includes the following steps: using plasma etching or non-plasma etching to roughen the surface of the silicon wafer; controlling the DRIE process parameters, directly Preparation of high-density and high aspect ratio nano-forest structures.

The process parameters for preparing the nano-forest by the DRIE include: the coil power is 800W-900W; _the pressure is 20mTorr-30mTorr; the flow rate of etching gas _SF6 is 20sccm-45sccm, and the flow rate of passivation gas _C4F8 is 30sccm-50sccm ( _SF6 and C ₄ F ₈ gas flow ratio is 1:1-1:2); plate power is 6W-12W; etching/passivation time ratio is 10s:10s-4s:4s; etching/passivation cycle 60-200 Second-rate.

In the above scheme, the process parameters described in step 3 include: the temperature is 50-100° C., and the time is 30 minutes-2 hours.

In the above scheme, the DRIE post-treatment process parameters described in step 4 include: the coil power is 800W-900W; _the pressure is 20mTorr-30mTorr; the flow rate of etching gas _SF6 is 0sccm, and the flow rate of passivation gas _C4F8 is 30sccm-50sccm ; The flat panel power is 6W-12W; the etching/passivation time ratio is 0s:10s-0s:4s; the etching/passivation cycle is 1-40 times.

Beneficial effects of the present invention:

1. The implantable three-dimensional drag-reducing microfluidic channel structure proposed by the present invention based on micro-nano integrated processing technology adopts the maskless optimized DRIE process, without destroying the original micron-scale structure, each micron groove High-density and high-aspect-ratio nanoscale cone tip arrays can be grown on the surface to achieve 100% coverage of the nano-forest on the micro-groove; and the above-mentioned micro-nano composite structure pattern can be transferred to the PDMS surface by using casting technology, so as to realize the real three-dimensional reduction. blocking microchannels.

2. The implantable three-dimensional drag-reducing microfluidic channel structure based on micro-nano integrated processing technology proposed by the present invention can greatly increase its area volume because a high-density nanoscale mesh array is prepared on each surface of the micro-groove Ratio, so that the surface of the microchannel has super-hydrophobic properties, achieving excellent drag reduction effect.

3. The preparation method of implantable three-dimensional drag-reducing microfluidic channels based on micro-nano integrated processing technology proposed by the present invention uses maskless optimized DRIE process and PDMS molding technology, and only two-step process is needed to realize PDMS micro-nano composite The structure and process are simple, the cost is low, and the industrialization is easy.

4. The preparation method of implantable three-dimensional drag-reducing microfluidic channels based on micro-nano integrated processing technology proposed by the present invention uses plasma technology to process PDMS cover plates and micron grooves, which can increase their roughness from the perspective of physical improvement, And from the perspective of chemical modification, depositing fluorine-based polymers reduces its surface energy, thereby further improving its stable superhydrophobic properties, thereby greatly improving its drag reduction effect.

Description of drawings

A more complete and better understanding of the invention, and many of its attendant advantages, will readily be learned by reference to the following detailed description when considered in conjunction with the accompanying drawings, but the accompanying drawings illustrated herein are intended to provide a further understanding of the invention and constitute A part of the present invention, the exemplary embodiment of the present invention and its description are used to explain the present invention, and do not constitute an improper limitation of the present invention, wherein:

Fig. 1 (a) is one of schematic diagrams of the implantable three-dimensional drag-reducing microfluidic channel structure based on micro-nano integrated processing technology of the present invention;

Fig. 1 (b) is the second schematic diagram of the implantable three-dimensional drag-reducing microchannel structure based on the micro-nano integrated processing technology of the present invention;

Fig. 1 (c) is the third schematic diagram of the implantable three-dimensional drag-reducing micro-channel structure based on micro-nano integrated processing technology of the present invention;

Fig. 2 is a process flow chart of the preparation method of an implantable three-dimensional drag-reducing microfluidic channel based on micro-nano integrated processing technology of the present invention;

Fig. 3 is the scanning electron micrograph of the micro-groove of the implantable three-dimensional drag-reducing micro-flow channel based on the micro-nano integrated processing technology of the present invention;

Fig. 4 is a scanning electron micrograph of the PDMS cover plate on the top of the implantable three-dimensional drag-reducing microchannel based on the micro-nano integrated processing technology of the present invention;

Fig. 5 is a test result diagram of the contact angle of the implantable three-dimensional drag-reducing microfluidic channel based on the micro-nano integrated processing technology of the present invention.

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Detailed ways

Obviously, many modifications and changes made by those skilled in the art based on the gist of the present invention belong to the protection scope of the present invention.

In order to make the above objects, features and advantages of the present invention more comprehensible, the embodiments of the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

The specific steps of an implantable three-dimensional drag-reducing microfluidic structure and its preparation method based on micro-nano integrated processing technology provided by the present invention will be described below with reference to accompanying drawings 1 to 5 .

With reference to Fig. 1, Fig. 1 (a) to Fig. 1 (c) are the structural representations of the implantable three-dimensional drag-reducing microfluidic channel based on micro-nano integrated processing technology of the present invention, and its cross-sections are respectively: Fig. 1 (a) inverted Triangular structure, Figure 1(b) inverted trapezoidal structure, Figure 1(c) semicircular structure. Its structure includes: a PDMS substrate 1, a PDMS cover plate 2, a micron groove 3, and a nanometer sieve array 4.

Referring to Fig. 2, Fig. 2 is a process flow chart of the preparation method of the implantable three-dimensional drag-reducing microchannel based on the micro-nano integrated processing technology of the present invention. Then the preparation steps of the structures shown in Fig. 1(a) to Fig. 1(c) are as follows:

Step 110: by combining photolithography and chemical or physical etching, fabricate a micron groove mold on the silicon substrate, the cross section of which is triangular, trapezoidal or semicircular, and its characteristic size is 1 μm-1000 μm;

Step 120: Utilize the maskless optimized deep reactive ion etching process to directly fabricate a high-density and high aspect ratio nano-forest structure on the silicon-based micro-groove mold and smooth silicon wafer surface, with a diameter of 50nm-1000nm and a height of 100nm-5000nm , silicon cones with a spacing of 100nm-1000nm;

Step 130: Utilize the PDMS molding process to adjust the process parameters: the temperature is 50-100°C, the time is 30 minutes-2 hours, and the silicon-based micro-groove mold and the nano-forest are used as templates to realize the PDMS cover with the nano-mesh array 4 A plate 2 and a PDMS substrate 1, wherein the PDMS substrate 1 includes a micron groove 3;

Step 140: Use the DRIE post-treatment process to adjust the parameters to perform physical and chemical treatment on the PDMS cover plate 2 and the PDMS substrate 1, wherein the PDMS substrate 1 contains micron grooves 3 to reduce its surface energy and improve its stable superhydrophobic properties ;

Step 150: Bonding the PDMS substrate 1 and the PDMS cover plate 2 by high-temperature bonding or physical pressure at room temperature to form a closed micro-channel.

Referring to Fig. 3, Fig. 3 is a micro-groove scanning electron micrograph of the implantable three-dimensional drag-reducing micro-channel based on the micro-nano integrated processing technology of the present invention, its cross section is an inverted triangle, and the base material is PDMS. The cross-section in the above step 130 is an inverted triangle, an inverted trapezoid or a semicircle, the groove depth is 1 μm-500 μm, and the groove width is 1 μm-1000 μm.

Referring to FIG. 4, FIG. 4 is a scanning electron micrograph of the PDMS cover plate on the top of the implantable three-dimensional drag-reducing microchannel based on the micro-nano integrated processing technology of the present invention. The nano-sieve array described in step 130 has a diameter of 10 nm-1000 nm, a depth of 10 nm-5000 nm, and a pitch of 10 nm-1000 nm.

Referring to Fig. 5, Fig. 5 is a test result diagram of the contact angle of the implantable three-dimensional drag-reducing microfluidic channel based on the micro-nano integrated processing technology of the present invention. The contact angle is greater than 170° and has excellent super-hydrophobic drag-reducing characteristics.

As mentioned above, although the Example of this invention was demonstrated in detail, it is obvious to those skilled in the art that many modifications can be made as long as the inventive point and effect of this invention are not substantially deviated. Therefore, all such modified examples are also included in the protection scope of the present invention.

Claims (7)

1. An implantable three-dimensional drag-reducing microfluidic preparation method based on micro-nano integrated processing technology, which is characterized in that: using maskless optimization deep reactive ion etching (DRIE) process, directly on each surface of micron-scale grooves Prepare and realize high-density and high-aspect-ratio nano-forest structures, and then use the casting method to transfer micron-scale grooves and nano-forest structures on the surface to PDMS, and then use the DRIE post-treatment process to perform physical and chemical surface treatment on the PDMS to reduce the surface energy. In this way, a PDMS three-dimensional drag-reducing microchannel with superhydrophobic properties is realized. 2. A method for preparing an implantable three-dimensional drag-reducing microfluidic channel based on micro-nano integrated processing technology according to claim 1, comprising: Step 1: By combining photolithography and chemical or physical etching, fabricate a micron trench mold on a silicon substrate with a triangular or trapezoidal or semicircular cross-section; Step 2: Utilize the maskless optimized deep reactive ion etching process to fabricate high-density and high aspect ratio nano-forests directly on silicon-based micro-groove molds and smooth silicon wafer surfaces; Step 3: Utilize the PDMS molding process, adjust the process parameters, and use the silicon-based micro-groove mold and nano-forest as a template to realize a PDMS cover plate with a nano-mesh array, a PDMS substrate, and a micro-groove; Step 4: Use the DRIE post-treatment process to adjust the parameters to perform physical and chemical treatments on the PDMS cover plate and the PDMS substrate, wherein the PDMS substrate contains micron grooves to reduce its surface energy and improve its stable superhydrophobic properties; Step 5: Bond the PDMS substrate and the PDMS cover plate by high-temperature bonding or physical pressure at room temperature to form a closed microchannel. 3. A method for preparing an implantable three-dimensional drag-reducing microfluidic channel based on micro-nano integrated processing technology according to claim 1 or 2, characterized in that: maskless optimized deep reactive ion etching described in step 2 The process includes the following steps: roughening the surface of the silicon wafer by plasma etching or non-plasma etching; controlling the DRIE process parameters to directly prepare a high-density and high-aspect-ratio nano-forest structure. 4. A method for preparing an implantable three-dimensional drag-reducing microfluidic channel based on micro-nano integrated processing technology according to claim 1 or 2, characterized in that: said DRIE process parameters for preparing nano-forests include: coil power of 800W-900W; the pressure is 20mTorr-30mTorr; the flow rate of etching gas SF ₆ is 20sccm-45sccm, the flow rate of passivation gas C ₄ F ₈ is 30sccm-50sccm (the gas flow ratio of SF ₆ and C ₄ F ₈ is 1:1-1 : 2); the plate power is 6W-12W; the etching/passivation time ratio is 10s:10s-4s:4s; the etching/passivation cycle is 60-200 times. 5. A method for preparing an implantable three-dimensional drag-reducing microfluidic channel based on micro-nano integrated processing technology according to claim 1 or 2, characterized in that: the process parameters described in step 3 include: the temperature is 50-100 ℃, and the time is 30 minutes to 2 hours. 6. A method for preparing an implantable three-dimensional drag-reducing microfluidic channel based on micro-nano integrated processing technology according to claim 1 or 2, characterized in that: the DRIE post-treatment process parameters described in step 4 include: coil power The pressure is 800W-900W; the pressure is 20mTorr-30mTorr; the flow rate of etching gas SF ₆ is 0 sccm, the flow rate of passivation gas C ₄ F ₈ is 30 sccm-50 sccm; the power of the plate is 6W-12W; the etching/passivation time ratio is 0s: 10s-0s: 4s; etching/passivation cycle 1-40 times. 7. An implantable three-dimensional drag-reducing micro-channel structure based on micro-nano integrated processing technology, which is characterized by comprising: PDMS substrate, PDMS cover plate, micro-groove, nano-sieve array; The substrate and the cover plate are polydimethylsiloxane with a thickness of 50 μm-1000 μm; The cover plate is bonded to the substrate; The micron groove is made on the substrate, and the closed cavity is formed by the substrate and the cover plate. The cross section is an inverted triangle, inverted trapezoid or semicircle, and its characteristic size is 10 μm-1000 μm; The nano-sieve array is made on the surface of the micro-groove, and is a sieve with a diameter of 10nm-1000nm, a depth of 10nm-5000nm, and a spacing of 10nm-1000nm.

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