CN114433261B - Nano-fluidic chip processing method based on carbon nanotube channel - Google Patents

Abstract

The invention provides a nano-fluidic chip processing method based on a carbon nano-tube channel. The method comprises the following steps: spin-coating a thin layer of photoresist on the substrate with water removed and heating to cure it; transferring the carbon nano tube thin layer to a preset position on the surface of the photoresist thin layer by a thermolysis method; spin-coating another layer of photoresist on the surface of the photoresist thin layer to embed the carbon nano tube therein; heating to volatilize the photoresist solvent, then carrying out photoetching operation, processing an open type micron channel system on the substrate, and exposing the carbon nano tube part in the microfluidic channel after the photoetching operation; pouring liquid PDMS into the channel, embedding the carbon nano tubes exposed in the channel into the PDMS, curing and stripping the PDMS to obtain the nano-fluidic chip substrate with the carbon nano tube channel; and (3) carrying out plasma oxidation treatment on the surface of PDMS (polydimethylsiloxane), carrying out plasma surface oxidation treatment on the PDMS and the nanofluidic chip substrate of the carbon nano-tube channel in S5, and finally carrying out chip bonding to obtain the nanofluidic chip constructed based on the carbon nano-tube. The invention has good integrity and high manufacturing efficiency.

Description

A nanofluidic chip processing method based on carbon nanotube channels

technical field

The invention relates to the technical field of nanofluidic chip processing, in particular to a nanofluidic chip processing method based on low-dimensional materials such as carbon nanotube channels.

Background technique

Nanofluidic technology is a science that studies the transmission, manipulation and application of scale molecules, ions, particles and other substances in the nanoscale space (1-100nm). The key to the development of nanofluidic technology lies in the processing of nanofluidic chips, including the construction of nanoscale fluid control systems. The inner diameter of carbon nanotubes is controllable (tens of nanometers to several nanometers) and is comparable to the size of molecules, which provides a pole for detecting and manipulating single nanometer-sized objects, such as cations, deoxyribonucleic acid, small organic molecules and solid nanoparticles. good platform. The uniformity of carbon nanotubes can effectively promote the unique transport mechanism of nanospace, such as the ultra-fast transport of molecules caused by the superhydrophobic inner surface of carbon nanotubes and the special phase transition of water in nanotubes; its TPa-level Young's mode Quantity and high chemical inertness can effectively prevent mechanical deformation and chemical deterioration during application; in addition, the production efficiency and cost of synthesizing ultra-long carbon nanotubes by chemical vapor deposition and other methods are higher than those of other nanopores; and bionano Nanofluidic devices based on carbon nanotubes are more stable than the pores sensitive to temperature, pH and salt concentration; finally, the chemical properties of carbon nanotube pores can be changed by covalent or non-covalent molecular bonding, especially for Modifications of carbon nanotube ends can be used to monitor specific targets. Based on these advantages, more and more researches focus on the research of nanofluidic devices based on carbon nanotubes.

Nanofluidic devices with a single carbon nanotube or multiple carbon nanotubes as fluid channels have been reported, and these systems can be roughly divided into two directions, namely, vertical carbon nanotube channels and horizontal carbon nanotube channels. The route to fabricate vertical CNT chips is to embed isolated CNTs in epoxy resin and slice them, and these slices with the same nanopores are further mounted on independent membrane scaffolds to form the final device. This method can manufacture many identical chips at one time, but the disadvantage of this method is that these chips are not convenient for on-chip integration, and the inlet and outlet of the chip are on both sides of the channel, and the chip is three-dimensional, which is inconvenient to operate; manufacturing vertical carbon Another approach for nanotube channeling is to insert well-dispersed ultrashort carbon nanotubes into lipid membranes, but the ultrasonic-assisted cleavage process destroys the integrity of the carbon nanotube walls and makes the lipid layer less mechanically stable than the solid state. devices and epoxy chips. Development of a planar-based carbon nanotube nanofluidic device, in which the carbon nanotubes are horizontally positioned on the substrate during the fabrication process, covered with a layer of photoresist by spin coating, and then photolithography is carried out by electron beam , but this method requires subsequent shearing of the carbon nanotubes by high-power plasma, however, the efficiency of plasma cutting carbon nanotubes or removing the caps of carbon nanotubes is not high, especially for multi-walled carbon nanotubes, shearing The effect is poor. At the same time, although the above-mentioned nanofluidic chips based on carbon nanotubes can perform optical and electrical detection at the same time, most of the above-mentioned chips are not optically transparent, which is not convenient for optical testing requirements in special occasions. Based on the technical deficiencies of the above-mentioned processing methods, this patent proposes a new method for processing planarly arranged carbon nanotube nanofluidic chips using a thermal transfer method combined with a mechanical shearing scheme.

Contents of the invention

According to the technical problems raised above, a method for processing nanofluidic chips based on carbon nanotube channels is provided. The technical means adopted in the present invention are as follows:

A nanofluidic chip processing method based on a carbon nanotube channel, comprising the following steps:

S1. Spin-coat a thin layer of photoresist on the dehydrated substrate and heat it to cure;

S2, transferring the carbon nanotube thin layer to a predetermined position on the surface of the photoresist thin layer by pyrolysis;

S3, spin coating another layer of photoresist on the surface of the photoresist thin layer to embed carbon nanotubes therein;

S4. Heating to volatilize the photoresist solvent, and then performing a photolithography operation to process an open micro-channel system on the substrate. After the photolithography operation, the carbon nanotubes are partially exposed in the microfluidic channel;

S5. Pour liquid PDMS into the channel, embed the carbon nanotubes exposed in the channel into PDMS, solidify and peel off the PDMS, and obtain a nanofluidic chip substrate with carbon nanotube channels;

S6. Perform plasma oxidation treatment on the PDMS surface, perform plasma surface oxidation treatment on it and the nanofluidic chip substrate of the carbon nanotube channel described in S5, and finally perform chip bonding to obtain a nanofluidic chip based on carbon nanotubes. .

Further, in the step S1, the substrate is a material that can provide flat and stable surface features, including glass materials, silicon-based materials, and silicon dioxide. The water removal process can be heated to 140-160 °C under normal pressure. ℃ and maintain for 25 to 35 minutes to achieve.

Further, the step S2 specifically includes the following steps: first, separate a thin layer of carbon nanotubes from the array of carbon nanotube bundles, and transfer the layer of carbon nanotubes to a layer of flexible polydimethylsiloxane flat plate (Polydimethylsiloxane , PDMS) surface, and then attach the PDMS with carbon nanotubes on the predetermined position of the thin layer of photoresist, remove the air bubbles introduced during the attachment process, heat the substrate to melt the photoresist, and then cool the substrate to At room temperature, the PDMS layer was removed to complete the transfer of carbon nanotubes.

Further, the PDMS used is PDMS with a low Young's modulus and has a certain viscosity on the surface, and the PDMS used is heated at 70-80°C through a liquid mixture with a ratio of bulk and curing agent of 10:1-15:1. About 2 hours to get.

Further, the carbon nanotubes used are a single carbon nanotube or a carbon nanotube array film, and the thickness of the carbon nanotube array film is less than 1 μm; a single carbon nanotube or a carbon nanotube array film can be pasted multiple times by adhesive tape and separation obtained.

Further, the photoresist in said S3 is a positive or negative resist, and should be the same type of photoresist as the selected photoresist in S1, and the thickness of the photoresist that is spin-coated is greater than that of the carbon nanotube film. thickness, into which carbon nanometers are embedded.

Further, the step S4 specifically includes the following steps: the photolithography mask used in the photolithography process should be designed according to the photoresist used in steps S1 and S3; after the photolithography is developed, the designed carbon nanotube flow channel Some parts should be embedded in the photoresist, other parts should be exposed in the channel.

Further, in the step S5, the liquid mixture of the PDMS body and the curing agent at a ratio of 10:1 to 15:1 is poured into the microfluidic channel described in S4, and vacuum degassing is performed, and the carbon nanometers exposed in the channel The tubes are completely embedded in PDMS, and after the PDMS is cured, the PDMS is peeled off to realize the mechanical shearing of the carbon nanotubes, and the substrate of the carbon nanotube micro-nanofluidic system is obtained.

Further, an optically transparent adhesive film and a plasma treatment method are used in the bonding process of the step S6; specifically, a PDMS plate is subjected to plasma surface treatment and a layer of polyacrylic acid adhesive film is attached to it. surface, and then punch holes in the corresponding positions to provide sample pools for the microfluidic channels, and then perform plasma oxidation treatment on the PDMS plate and the carbon nanotube micro-nanofluidic system substrate described in S5, by combining the PDMS plate substrate and The carbon nanotube micro-nanofluidic system substrate is aligned and bonded to realize the processing of the nanofluidic chip based on the carbon nanotube channel.

Furthermore, the inner diameter of the carbon nanotubes is on the order of nanometers, so that the processed nanofluidic chip can realize the controllable operation detection of substances at the molecular level, and at the same time, the use of ultra-long carbon nanotubes can realize complex nanofluidic systems on the plane build.

The present invention has the following advantages:

1. Good integrity. The method of wrapping and cutting carbon nanotubes by mechanical shearing force adopted in the present invention will not destroy the structure of carbon nanotubes in the channels, and realizes the integrity of the carbon nanotube channels.

2. High production efficiency. Compared with the commonly used process of plasma cutting carbon nanotubes, the process used in the present invention can complete the cutting of all carbon nanotubes in the whole chip at one time (shearing efficiency is nearly 100%), and has higher cutting efficiency.

3. Good economy. The method adopted in the present invention realizes cutting of carbon nanotube channels at lower cost while ensuring channel functions, has a simple preparation process, requires less high-end equipment, and is easier to operate and popularize in practical applications.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description These are some embodiments of the present invention. For those skilled in the art, other drawings can also be obtained according to these drawings without any creative effort.

Figure 1 is a flow chart of the method of the present application.

Fig. 2 is an explanatory diagram of the nanofluidic chip processing method for carbon nanotube channels, in which: (a) spin-coating photoresist on the substrate; (b) transferring carbon nanotubes to the photoresist surface by pyrolysis ; (c) spin-coat photoresist again to embed carbon nanotubes in the photoresist layer; (d) build microfluidic channels in the photoresist layer by ultraviolet exposure; (e) expose both ends of carbon nanotubes to microfluidic (f) Precise shearing of carbon nanotubes using PDMS pouring, curing, and peeling off; (g) Nanofluidic chip substrate with carbon nanotube channels; (h) Plasma oxidation treatment on the surface of the PDMS plate; (i ) attaching a double-sided adhesive layer on the surface of PDMS and punching holes; (j) performing plasma oxidation treatment on the surface of the PDMS flat plate and the substrate of the carbon nanotube nanofluidic chip; (k) bonding the chip.

Figure 3 shows an example of photos during the processing of nanofluidic chips based on carbon nanotubes, in which (a) carbon nanotubes embedded in the photoresist layer after ultraviolet exposure; (b) microfluidic channels after development, carbon nanotubes Tube ports exposed in microfluidic channels; (c) carbon nanotubes mechanically sheared by PDMS; (d) chip after bonding.

Figure 4 is an example of a nanofluidic chip with carbon nanotube channels combined with electrochemical detection technology based on the carbon nanotube chip processing method, in which (a) is stripped and transferred to the carbon nanotube film on the PDMS surface; (b) and Carbon nanotube nanofluidic chip combined with electrochemical detection technology; (c) Enlarged picture of carbon nanotubes on the chip.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments It is a part of embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

As shown in Figure 1, the embodiment of the present invention discloses a nanofluidic chip processing method based on carbon nanotube channels. The present invention provides an efficient and reliable nanofluidic chip based on carbon nanotubes for the field of micro-nanofluidics Chip processing technology, including the following steps:

S1. Spin-coat a thin layer of photoresist on the dehydrated substrate and heat it to cure;

S2, transferring the carbon nanotube thin layer to a predetermined position on the surface of the photoresist thin layer by pyrolysis;

S3, spin coating another layer of photoresist on the surface of the photoresist thin layer to embed carbon nanotubes therein;

S4. Heating to volatilize the photoresist solvent, and then performing a photolithography operation to process an open micro-channel system on the substrate. After the photolithography operation, the carbon nanotubes are partially exposed in the microfluidic channel;

S5. Pour liquid PDMS into the channel, embed the carbon nanotubes exposed in the channel into PDMS, solidify and peel off the PDMS, realize precise mechanical shearing of carbon nanotubes, and obtain a nanofluidic chip substrate with carbon nanotube channels ;

S6. Perform plasma oxidation treatment on the surface of PDMS, attach a layer of double-sided adhesive, perform plasma surface oxidation treatment with the nanofluidic chip substrate of the carbon nanotube channel described in S5 after drilling, and finally perform chip bonding to obtain Nanofluidic chips based on carbon nanotubes.

In the step S1, the substrate is a material that can provide flat and stable surface features, including glass materials, silicon-based materials, and silicon dioxide. The water removal process can be heated to 140-160°C under normal pressure and kept It takes 25 to 35 minutes to realize. In this embodiment, the water removal process can be realized by heating to 150° C. under normal pressure and maintaining it for 30 minutes.

The step S2 specifically includes the following steps: first, separate a thin layer of carbon nanotubes from the array of carbon nanotube bundles, and transfer the layer of carbon nanotubes to a layer of flexible polydimethylsiloxane (Polydimethylsiloxane, PDMS) flat plate surface, and then attach the PDMS with carbon nanotubes on the predetermined position of the thin layer of photoresist, remove the air bubbles introduced during the attachment process, heat the substrate to melt the photoresist, and then cool the substrate to room temperature to remove PDMS layer to complete the transfer of carbon nanotubes.

The PDMS used is PDMS with a low Young's modulus and the surface has a certain viscosity. The PDMS used is heated at 70-80°C for about 2 hours through a liquid mixture with a ratio of 10:1 to 15:1 of the bulk and curing agent. Obtained, in this example, the PDMS used is obtained by mixing the bulk and the curing agent at a ratio of 15:1 and then heating at 75°C for 2 hours.

The carbon nanotubes used are a single carbon nanotube or a carbon nanotube array film, and the thickness of the carbon nanotube array film is less than 1 μm; a single carbon nanotube or a carbon nanotube array film can be obtained by pasting and separating multiple times with an adhesive tape . As an alternative, the thermal release transfer method described in S2 can be extended to the transfer method of other channel materials, specifically, it can be extended to the operation, transfer and nanofluidic chip fabrication of other nanomaterials, such as graphene, oxide Graphene, MoS2, TiO2 and other nanomaterials.

The surface of the photoresist and the carbon nanotube layer in S3 is spin-coated with another layer of photoresist, the selected spin-coated photoresist and the first layer of photoresist are the same type of photoresist, and the photoresist is a positive photoresist Or negative resist, the thickness of the spin-coated photoresist is greater than the thickness of the carbon nanotube film, and the carbon nanometers are embedded in it.

The step S4 specifically includes the following steps: in the photolithography operation, a microfluidic channel is made on the photoresist layer, and the microfluidic channel system is connected to the carbon nanopipe. The photoresist is used for design; after the photolithography is developed, the part of the designed carbon nanotube flow channel should be embedded in the photoresist, and the other part should be exposed in the channel.

In the step S5, pouring the liquid mixture of the PDMS body and the curing agent at a ratio of 10:1 to 15:1 in the microfluidic channel described in S4, performing vacuum degassing, and completely embedding the carbon nanotubes exposed in the channel In PDMS, after the PDMS is cured, the PDMS is peeled off to realize the mechanical shearing of the carbon nanotubes, and the substrate of the carbon nanotube micro-nanofluidic system is obtained.

In the bonding process of step S6, an optically transparent adhesive film and a plasma treatment method are used; in the bonding process of the carbon nanotube nanofluidic chip, in order to obtain a sealed nanofluidic device, an optically transparent adhesive film is used in the bonding process. Composite film (polyacrylic acid) and plasma treatment method; Specifically, a PDMS plate is subjected to plasma surface treatment and a layer of polyacrylic acid adhesive film is attached to its surface, and then holes are punched in corresponding positions to provide micro The flow channel provides a sample pool, and then the PDMS plate and the carbon nanotube micro-nanofluidic system substrate described in S5 are subjected to plasma oxidation treatment together, by aligning the PDMS plate substrate and the carbon nanotube micro-nanofluidic system substrate Bonding realizes the processing of nanofluidic chips based on carbon nanotube channels.

The inner diameter of the carbon nanotubes is on the order of nanometers, so that the processed nanofluidic chip can realize the controllable operation and detection of substances at the molecular level, such as the controllable transmission of ions, and the counting and detection of macromolecules. The carbon nanotubes can realize the construction of complex nanofluidic systems on the plane.

Example 1

The concrete method of this embodiment is as follows:

As shown in Figure 2(a), a thin layer of photoresist is spin-coated on a water-removing substrate and heated to cure it. The substrate used is a silicon wafer with a thickness of 1mm. The silicon wafer is heated to 150°C under normal pressure and kept for 30 minutes to remove water, and then spin-coated on the silicon wafer immediately after the silicon wafer is cooled. The spin-coated photoresist is SU8-3005, spin-coated with a thickness of 5 μm, heated at 95°C for 2 minutes after spin-coating to completely evaporate the solvent;

The carbon nanotube thin layer is transferred to a predetermined position on the surface of the photoresist thin layer by a pyrolysis method. Concrete steps and parameters are as follows: as Fig. 4 (a), adopt adhesive tape to separate a bunch of carbon nanotubes from the carbon nanotube bundle that vertically grows on the silicon wafer, the internal diameter of described carbon nanotubes is on the order of nanometers, and length is It is about 5mm and the thickness is less than 1 μm; then transfer this layer of carbon nanotubes to the surface of a flexible polydimethylsiloxane (Polydimethylsiloxane, PDMS) flat plate, the PDMS used is PDMS with a low Young’s modulus, the PDMS The processing process adopts the ratio of body and curing agent as 15:1, the heating temperature of pre-cured PDMS is 75°C, and the heating time is 2 hours. The surface has a certain viscosity; as shown in Figure 2(b), and then carbon nanotubes will be stuck The PDMS is attached to the predetermined position of the thin layer of photoresist, and the carbon nanotubes are kept facing the side of the photoresist during the attachment process while eliminating the air bubbles introduced during the attachment process; then the substrate is heated at 90 ° C and kept for 1 The photoresist is melted in a few minutes, so that the carbon nanotubes are embedded in the melted photoresist layer; then the sample is cooled to room temperature; then the PDMS layer is removed to complete the transfer of the carbon nanotubes;

As shown in Figure 2(c), another layer of photoresist is spin-coated on the surface of the first photoresist thin layer to embed carbon nanotubes therein. The spin-coated photoresist is SU8-3050, the spin-coating thickness is 50 μm, and the spin-coated photoresist can completely cover the carbon nanotube film;

After heating the sample to volatilize the solvent in the photoresist, perform a photolithography operation, and process an open micron channel system on the substrate. During the photolithography operation, the two ends of the carbon nanotubes that will be embedded in the photoresist layer are aligned through the photolithography mask exposed to the channel. As shown in Figure 2(d) and Figure 3(a), the specific parameters of the photolithography operation to make microfluidic channels in the photoresist layer are: heat the sample at 65°C for 5 minutes, then turn it to 95°C for 15 minutes, and wait for it to cool Afterwards, UV exposure is carried out, the exposure dose is 430mJ/cm ² , post-baking heating is carried out after exposure, specifically heating at 65°C for 1 minute, then heating at 95°C for 6 minutes, and then heating at 65°C for 1 minute to reduce the photolithography The thermal stress of the adhesive film; as shown in Figure 2(e) and Figure 3(b), the cooled sample was developed for 5 minutes; after photolithographic development, the carbon nanotubes were partially embedded in the photoresist, and the carbon Other parts of the nanotubes are exposed in the channel for shearing in subsequent steps;

As shown in Figure 2(f)-(g), Figure 3(c), Figure 4(b)-(c), pour liquid PDMS into the channel to embed the carbon nanotubes exposed in the channel into PDMS, and then cure the PDMS And peel off, realize the precise mechanical shearing of carbon nanotubes, and obtain the nanofluidic chip substrate with carbon nanotube channels. In the shearing process of carbon nanotubes, the preparation formula of liquid PDMS is that the ratio of PDMS body and curing agent is 10:1, and the liquid PDMS pre-cured mixture is poured in the above-mentioned microfluidic channel, and vacuum degassing is performed, and the exposed The carbon nanotubes in the medium are completely embedded in PDMS, and the PDMS is heated at 90°C for 2 hours to be cured, and then the PDMS is peeled off to realize the mechanical shearing of the carbon nanotubes, and the substrate of the carbon nanotube micro-nanofluidic system is obtained;

As shown in Figure 2(h)-(k) and Figure 3(d), the bonding of nanofluidic chips based on carbon nanotubes. The specific steps and parameters of the bonding are: plasma oxidation treatment is performed on the surface of the PDMS plate, the treatment time is 90s, and the treatment power is 30W; then a layer of polyacrylic double-sided adhesive is attached to the treated PDMS surface, and the thickness of the adhesive layer is 25μm ; Punch the PDMS plate with the adhesive layer to provide a liquid storage pool for the nanofluidic chip; and then perform plasma surface oxidation treatment on the nanofluidic chip substrate of the carbon nanotube channel and the PDMS plate again, and the treatment time is 90s. The processing power is 30W; finally, the PDMS plate and the nanofluidic chip substrate with carbon nanotube channels are bonded for chip bonding to obtain a nanofluidic chip based on carbon nanotubes.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: It is still possible to modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the various embodiments of the present invention. scope.

Claims (8)

1. A nano-fluidic chip processing method based on a carbon nano-tube channel is characterized by comprising the following steps:

s1, spin-coating a thin layer of photoresist on a substrate with water removed and heating to solidify the photoresist;

s2, transferring the carbon nanotube thin layer to a preset position on the surface of the photoresist thin layer through a thermolysis method;

s3, spin-coating another layer of photoresist on the surface of the photoresist thin layer to embed the carbon nano tube into the photoresist thin layer;

s4, heating to volatilize the photoresist solvent, then carrying out photoetching operation, processing an open type micro-channel system on the substrate, and exposing the carbon nano tube part in the micro-flow channel after the photoetching operation;

s5, pouring liquid PDMS into the channel, embedding the carbon nano tubes exposed in the channel into the PDMS, curing and stripping the PDMS to realize mechanical shearing of the carbon nano tubes, and obtaining the nanofluidic chip substrate with the carbon nano tube channel;

s6, carrying out plasma oxidation treatment on the surface of PDMS (polydimethylsiloxane), carrying out plasma surface oxidation treatment on the PDMS and the nanofluidic chip substrate of the carbon nano-tube channel in S5, and finally carrying out chip bonding to obtain a nanofluidic chip constructed based on the carbon nano-tube;

the step S2 specifically includes the following steps: firstly, separating a thin layer of carbon nanotubes from a carbon nanotube bundle array, transferring the layer of carbon nanotubes to the surface of a layer of flexible polydimethylsiloxane flat plate, namely the surface of a PDMS flat plate, then attaching PDMS adhered with the carbon nanotubes to a preset position of thin-layer photoresist, removing bubbles introduced in the attaching process, heating a substrate to melt the photoresist, then cooling the substrate to room temperature, removing the PDMS layer, and finishing the transfer of the carbon nanotubes;

the adopted PDMS is the PDMS with a lower Young modulus and has certain viscosity on the surface, and is obtained by heating a liquid mixture of a body and a curing agent in a ratio of 10 to 1 to 20 at 70 to 80 ℃ for a preset time.

2. The machining method of the nanofluidic chip based on the carbon nanotube channel as claimed in claim 1, wherein in the step S1, the substrate is made of a material capable of providing a smooth and stable surface feature, and the material comprises a glass material, a silicon-based material and silicon dioxide, and the water removal process is performed by heating to 140 to 160 ℃ under normal pressure and maintaining for 25 to 35 minutes.

3. The method for processing nanofluidic chip based on carbon nanotube channels of claim 1, wherein the carbon nanotubes used are single carbon nanotubes or carbon nanotube array films, the thickness of the carbon nanotube array film is less than 1 μm; the single carbon nanotube or the carbon nanotube array film is obtained by sticking and separating the adhesive tape for multiple times.

4. The method for processing a nanofluidic chip based on carbon nanotube channels as claimed in claim 1, wherein the photoresist in S3 is positive or negative and should be the same kind of photoresist as the photoresist selected in S1, the thickness of the spin-coated photoresist is larger than that of the carbon nanotube film, and carbon nanotubes are embedded therein.

5. The method for processing a nanofluidic chip based on carbon nanotube channels as claimed in claim 1, wherein the step S4 comprises the following steps: the photolithographic mask used in the photolithographic process should be designed according to the photoresist used in steps S1 and S3; after photolithography and development, the designed carbon nanotube flow channel should be partially embedded in the photoresist, and the other part should be exposed in the channel.

6. The machining method of the nanofluidic chip based on the carbon nanotube channel according to claim 1, wherein in the step S5, a liquid mixture of a PDMS body and a curing agent in a ratio of 10 to 1 to 15 is poured into the microfluidic channel in S4, vacuum degassing is performed, the carbon nanotube exposed in the channel is completely embedded into the PDMS, and the PDMS is peeled off after curing to realize mechanical shearing of the carbon nanotube, so that the nanofluidic chip substrate with the carbon nanotube channel is obtained.

7. The method for processing a carbon nanotube channel-based nanofluidic chip as claimed in claim 1, wherein the step S6 bonding process employs an optically transparent adhesive film and a plasma treatment method; specifically, a PDMS flat plate is subjected to plasma surface treatment, a layer of polyacrylic acid adhesive film is attached to the surface of the PDMS flat plate, then holes are formed in corresponding positions to provide a sample pool for the microfluidic channel, then the PDMS flat plate and the nanofluidic chip substrate with the carbon nanotube channel, which is described in S5, are subjected to plasma oxidation treatment together, and the processing of the nanofluidic chip based on the carbon nanotube channel is realized by aligning and attaching the PDMS flat plate substrate and the nanofluidic chip substrate with the carbon nanotube channel.

8. The method as claimed in claim 1, wherein the inner diameter of the carbon nanotube is in the order of nanometers, so that the fabricated nanofluidic chip can realize the controllable operation and detection of substances in molecular level, and the construction of complex nanofluidic system on a plane can be realized by using the ultra-long carbon nanotube.

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