Method for forming annular micro-channel in conductive polymer PMMA / CB based on thermal-electric coupling effect

Abstract

The invention relates to a method for forming an annular micro-channel in a conductive polymer PMMA / CB material based on a thermal-electric coupling effect, which comprises the following processing steps of: 1, performing annular array hole processing on the conductive polymer PMMA / CB, and processing micropores in an annular array on the surface of the conductive polymer PMMA / CB; 2, performing thermal field processing on the conductive polymer PMMA / CB treated in the step 1, and heating the conductive polymer PMMA / CB to a viscous flow state so as to form an internal micro-channel structure; and applying a rotating electric field to form the internal annular micro-channel. Based on a phase field model theory, the conductive polymer PMMA / CB is used for processing by using a thermal-electric coupling method, and a new scheme is provided for manufacturing the internal annular micro-channel.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of micro-nano manufacturing and processing, and particularly relates to a forming method of an internal annular microchannel of a conductive polymer PMMA / CB based on a thermal-electric coupling effect. BACKGROUND

[0002] The conductive polymer has excellent electrical conductivity and flexible processing characteristics, and in recent years has shown great application potential in the fields of microelectronic devices, biosensors and medical engineering. The construction of a high-precision annular microchannel structure in the conductive polymer can realize local electric field regulation, electrochemical sensing and microfluidic driving functions. However, due to the limited strength and plasticity of the conductive polymer itself, problems such as channel collapse, deformation or blockage are prone to occur at the microscale, making the accurate manufacturing of high-aspect-ratio internal annular channels a great challenge.

[0003] At present, common microchannel processing methods include photolithography, chemical etching and soft mold imprinting technologies. Although these methods can achieve the formation of microchannels to some extent, there are still obvious limitations: first, the processing technology is complex and the cost is high, which is not conducive to large-scale production; second, the processing cycle is long and the efficiency is low; in addition, the size, shape and surface quality of the channel are difficult to accurately control, and high-aspect-ratio holes or annular microchannels often have uneven hole diameters, rough edges and other defects; more importantly, the hard processing method is easy to damage the flexible conductive polymer, making it difficult to maintain its original electrical conductivity and mechanical properties.

[0004] An ideal processing technology should have high processing efficiency, high structural precision, strong ability to form complex channels and little damage to the material, in order to meet the strict requirements of microelectronic devices, microfluidic systems and biosensors for internal microstructures. Therefore, there is an urgent need in the art to develop a new processing method that can realize high-precision and controllable internal annular microchannel manufacturing in the conductive polymer while ensuring its electrical conductivity and mechanical properties. SUMMARY

[0005] In view of the above problems existing in the prior art, based on the phase field model theory, the internal annular microchannel of the conductive polymer PMMA / CB (polymethyl methacrylate / carbon black, which is a conductive polymer) is manufactured and processed by introducing a rotating electric field on the basis of a temperature field and changing the strength, frequency, current size and duration of thermal-electric coupling of the rotating electric field.

[0006] In order to achieve the purpose of the application, the technical scheme adopted by the application is as follows:

[0007] The forming method of the internal annular microchannel of the conductive polymer PMMA / CB based on thermal-electric coupling is performed according to the following steps:

[0008] Step one, the conductive polymer PMMA / CB ring array hole processing, on the surface of the conductive polymer PMMA / CB processing ring array of micro holes.

[0009] Step two, by the conductive polymer PMMA / CB after step one processing heat field processing, heated to viscous flow state, and then form the internal micro channel structure; again to apply a rotating electric field, to shape the internal ring micro channel.

[0010] Preferably, in step two, the micro hole processing of the conductive polymer PMMA / CB is cleaned and placed on the high temperature heating table, heated to viscous flow state, at this time based on the phase field model theory, the conductive polymer PMMA / CB will occur under the action of surface energy and internal stress small deformation. At this time the particles in the conductive polymer PMMA / CB under the action of surface energy will move to the direction of minimum energy, the micro hole surface will gradually heal, eventually form the internal micro channel structure, but due to the existence of internal stress in the material itself, the cross section roundness and overall ring quality of the micro channel after forming can not be guaranteed, at this time the rotating electric field is added, the internal ions migrate, and finally form regular internal ring micro channel, at this time the roundness, surface quality and other parameters will tend to be excellent.

[0011] Preferably, in step one, the parameters include the depth of the cylindrical hole, the radius of the hole, the circular arc angle and distance between the holes.

[0012] Preferably, in step two, based on the phase field model theory, the phase field dynamics model of PMMA / CB under the action of heat-electricity coupling, the total free energy equation of PMMA / CB under the action of heat-electricity coupling is:

[0013]

[0014] Wherein, G is the total free energy, is the order parameter, represents the volume free energy density in the system, using the double well potential function Since there are only two phases in the system and and represents the density only when the corresponding substance exists, so Where f0 is a constant; the second term represents the surface energy density of the conductive polymer PMMA / CB, h is the surface energy coefficient, is the Laplace operator; the third term represents the rotating electric field energy density, γ is the electric field-order parameter coupling strength constant, E(t) is the expression form of the rotating electric field, Where E0 represents the electric field amplitude, ω is the rotating frequency, respectively represent the polarization to x, y direction, dr represents the polarization direction; dr represents the volume differential element.

[0015] The annular microchannels in PMMA / CB are achieved through a driving force generated by atomic diffusion. This driving force is determined by the volume free energy density, surface free energy density, and rotating electric field energy density. The chemical potential energy μ that generates the driving force can be expressed as:

[0016]

[0017] The Cahn-Hilliard nonlinear equation can be derived from the surface atomic diffusion flux. In partial differential equations, this is reflected as follows:

[0018]

[0019] Where M is the atomic mobility of PMMA / CB. Combining the two equations above, the order parameter... The derivation of the state evolution equation is as follows:

[0020]

[0021] Preferably, in step one, the parameters of the micropores are processed according to the following formula:

[0022]

[0023] 0 <S≤1.76R

[0024] 0.568s≤R≤0.113L

[0025] 1°<θ arc <2°

[0026] The above formula defines the dimensional constraints that should be guaranteed during micro-hole processing, satisfying requirements such as high aspect ratio, low hole spacing, and high perpendicularity between holes. The micro-holes should be made as small as possible, with small enough spacing and large enough hole spacing to ensure that the holes can be accurately and quickly fused into an internal annular microchannel.

[0027] Where L is the depth of the hole, R is the radius of the hole, S is the distance between the holes, and θ is the distance between the holes. arc The radius of the hole should be as large as possible. It is large enough, and S is small enough.

[0028] In step one, the depth-to-width ratio of the hole is determined. With a value of 15 and a depth of 10μm, micron-level milling cutters or laser processing are used during machining. These parameter settings ensure the aspect ratio is optimal. It is large enough, and the distance s between the holes is small enough.

[0029] Preferably, in step two, the heating temperature of the conductive polymer PMMA / CB is 150 DEG C, and the conductive polymer PMMA / CB needs to be uniformly heated on a heat-conducting insulating heating plate. At this temperature, the material enters a viscous flow state, the shape of the microchannel can be precisely controlled, and uniform heating can reduce thermal stress, thereby ensuring the mechanical strength after processing and the conductivity of the material itself.

[0030] Preferably, in step three, a rotating electric field is applied to the conductive polymer PMMA / CB by using the orthogonal electrode plate method. The electrode ITO (indium tin oxide) conductive glass is placed around the PMMA / CB material with four mutually perpendicular surfaces, the electrode spacing is 5 mm, and a sinusoidal signal with the same frequency and amplitude is applied through a signal source, the voltage is set to 5Vpp, and the frequency is 100 Hz. Through the 5mm electrode spacing and the low-frequency alternating sinusoidal electric field of 1V / mm, the stable and controllable circular driving of the micro-scale particles or dielectric molecules can be realized without causing dielectric breakdown and polarization accumulation, thereby ensuring the stability of the experimental process.

[0031] Preferably, after the above steps, the internal circular microchannel structure is observed by SEM (scanning electron microscope).

[0032] In summary, the present application relates to a method for forming an internal circular microchannel of a conductive polymer PMMA / CB material based on the thermal-electric coupling effect, and the processing steps are as follows: step one, processing the conductive polymer PMMA / CB into a circular array of holes, and processing a circular array of micro-holes on the surface of the conductive polymer PMMA / CB; step two, establishing a total free energy equation of PMMA / CB under the thermal-electric coupling effect according to the phase field model, determining the driving force required for the fusion microchannel, and then placing it on a constant temperature heating table for heating. The material surface will gradually heal due to the action of surface energy, and an internal circular microchannel is preliminarily formed. A rotating electric field is added to modify the internal microchannel to ensure the roundness of the internal circular microchannel and the surface quality.

[0033] Compared with the prior art, the present application has the following remarkable technical effects:

[0034] To solve the technical problems of the microchannels manufactured by the existing methods such as laser ablation, photolithography process, and precision machining, such as high cost, complex process, high difficulty, and inability to form internal channels, the present application proposes a method for forming an internal circular microchannel of a conductive solid polymer based on the phase field model theory from the perspective of energy transfer of atoms, solves the aforementioned practical technical problems, and provides a new technical scheme for preparing an internal circular microchannel of a conductive polymer. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 is a schematic diagram of an experimental device for forming an internal circular microchannel of a conductive polymer PMMA / CB.

[0036] Figure 2 is a schematic view of the internal annular microchannel effect of the present application when only a thermal field is applied.

[0037] Figure 3 is a schematic view of the internal annular microchannel effect of the present application when a rotating electric field is applied.

[0038] Figure 4 is a schematic view of the forming process of the internal annular microchannel of the conductive polymer PMMA / CB under the action of thermal-electric coupling. DETAILED DESCRIPTION

[0039] The present application will be further described below in conjunction with the accompanying drawings and specific embodiments. Those skilled in the art will be able to implement the present application based on these descriptions. In addition, the embodiments of the present application involved in the following description are generally only a part of the embodiments of the present application, not all the embodiments. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments in the present application without making creative efforts should be within the scope of protection of the present application.

[0040] As Figure 1 is a schematic view of an experimental device for manufacturing the internal annular microchannel of the conductive polymer PMMA / CB, which includes a high-temperature heating platform 1, an insulating heat-conducting plate 2, an aluminum plate 3, an ITO conductive glass 4, a conductive polymer 5, a signal generator 6, and a Tesla meter 7.

[0041] When the annular array microholes are processed on the surface of the conductive polymer PMMA / CB by using a five-axis machining center, defects are generated on the material surface, which will inevitably generate certain mechanical stress. Therefore, when only a thermal field is applied, the thermal diffusion movement of the PMMA / CB surface atoms occurs. Due to the action of the mechanical stress, the circularity of the cross section of the annular microchannel, the inner wall surface quality, and the overall annular quality cannot be guaranteed, and even some holes cannot be fused, as shown in Figure 2 At this time, the present application provides a part of driving force by applying a rotating electric field to drive the annular hole array structure to change to an annular inner channel structure, as shown in Figure 3

[0042] Specifically, the preferred embodiment of the present application is a method for realizing the internal annular microchannel of the conductive polymer PMMA / CB based on thermal-electric coupling, which includes the following steps:

[0043] Step one: annular array hole processing is performed on the conductive polymer PMMA / CB by using laser processing to process the microholes in an annular array on the surface of the conductive polymer PMMA / CB. The parameters of the microholes are processed according to the following formula:

[0044] ​

[0045] 0 <S≤1.76R

[0046] 0.568s≤R≤0.113L

[0047] 1°<θ arc <2°

[0048] Where L is the depth of the hole, R is the radius of the hole, S is the distance between the holes, and θ is the distance between the holes. arc The radius of the hole should be as large as possible. Large enough, S small enough. In this embodiment, the conductive polymer PMMA / CB is clamped in a pre-machined fixture and secured with four screws to prevent it from loosening during machining, which could cause the machined arc angle to exceed the reasonable range. A micron-level milling cutter is used during machining, with a depth-to-width ratio (i.e., ...) (15), S is 10μm.

[0049] Step 2: Based on the phase-field model theory, establish a phase-field dynamic model of the conductive polymer PMMA / CB under thermo-electric coupling. The total free energy equation for PMMA / CB under thermo-electric coupling is:

[0050]

[0051] Where G is the total free energy, As an order parameter, Expressed as the volume free energy density of the system, using the dual-well potential function. Since there are only two phases in this system, and This represents the density when only the corresponding substance exists. Where f0 is a constant; the second term represents the surface energy density of the conductive polymer PMMA / CB, and h is the surface energy coefficient. For the Laplace operator; the third term represents the electric energy density of the rotating electric field, γ is the electric field-order parameter coupling strength constant, and E(t) is the expression for the rotating electric field. Where E0 represents the electric field amplitude, and ω is the rotation frequency. These represent polarization in the x and y directions, respectively. dr represents the polarization direction; dr represents the volume differential element.

[0052] The annular microchannels in PMMA / CB are achieved through a driving force generated by atomic diffusion. This driving force is determined by the volume free energy density, surface free energy density, and rotating electric field energy density. The chemical potential energy μ that generates the driving force can be expressed as:

[0053]

[0054] The Cahn-Hilliard nonlinear equation can be derived from the surface atom diffusion flux In partial differential equations, represented as:

[0055]

[0056] Where M is the PMMA / CB atomic mobility. In combination with equation (2), equation (3), the evolution equation of the order parameter is as follows:

[0057]

[0058] The micro-holed conductive polymer PMMA / CB is cleaned and placed on a high-temperature heating platform, and heated to a viscous flow state. At this time, under the action of high temperature, the surface high aspect ratio micro-holes in the conductive polymer PMMA / CB begin to shrink and heal, forming an internal ring cavity structure. Continuous heating causes the internal cavities to merge to form internal micro-channels. In this embodiment, the material is ultrasonically cleaned with pure water for about 15 minutes; after cleaning, the material is placed on a heat-conducting insulating heating plate and uniformly heated at a rate of 5℃ / min. First, dry it at 60℃ for 1 hour to prevent bubbles from forming due to internal water vapor during heating, then increase the temperature to 150℃ for 6 hours; cool down at a rate of 10℃ / min to prevent the material from deforming due to rapid cooling. The molding effect is shown in Figure 2 .

[0059] At this time, the particles in the conductive polymer PMMA / CB in the viscous flow state will move in the direction of minimum energy under the action of surface energy, and the micro-hole surface will gradually heal, eventually forming an internal micro-channel structure. However, due to internal stress in the material itself, the cross-sectional roundness and overall ring quality of the micro-channel after molding cannot be guaranteed. At this time, a rotating electric field is added, and internal ions undergo electric migration, eventually forming a regular internal ring micro-channel. In this embodiment, an oscillation signal with the same sine frequency and amplitude is applied to the conductive polymer PMMA / CB material (orthogonal electrode method is used, and a signal source is used to apply an electric signal to the orthogonal electrode plate), the voltage is set to 5Vpp, the frequency is 100Hz, and a Tesla meter is used for measurement. After the hole forming is completed, the signal source is immediately turned off, and the internal ring micro-channel structure is observed by SEM scanning electron microscope, and the molding effect is shown in Figure 3 .

[0060] In summary, the application proposes a forming method of internal annular microchannels in conductive polymer PMMA / CB based on the thermoelectric coupling effect, which aims to solve the technical problems of structural limitations, high processing cost and poor surface quality in traditional microchannel manufacturing technology. By introducing a rotating electric field and constructing a phase field model, the controlled migration and structural evolution of material particles in a high temperature viscous flow state are realized, and finally a regular and high-quality annular microchannel structure is formed inside. This method not only breaks through the problem of internal channel manufacturing in traditional processes, but also provides a new theoretical basis and process path for the internal microstructure design and manufacturing of conductive polymer flexible devices, and has good application prospect and engineering popularization value.

[0061] The above only describes the preferred embodiments and principles of the application in detail. For ordinary skilled persons in the art, the specific implementation methods will be changed according to the idea provided by the application, and these changes should be regarded as the protection scope of the application.

Claims

1. A method for forming a microchannel based on the thermoelectric coupling of an electrically conductive polymer PMMA / CB internal ring, characterized in that, The following steps are taken: Step 1, the conductive polymer PMMA / CB is processed into a ring array hole, and a ring array of micro-holes is processed on the surface of the conductive polymer PMMA / CB; Step 2, by heat field processing the conductive polymer PMMA / CB treated in step 1, it is heated to viscous flow state, and then the internal micro-channel structure is formed; then a rotating electric field is applied to form the internal ring-shaped micro-channel.

2. The molding method according to claim 1, wherein In step one, the parameters of the ring-shaped hole include the depth of the hole, the radius of the hole, the angle and distance between the holes.

3. The molding method according to claim 2, wherein In step one, the processing is carried out according to the following formula: where L is the depth of the hole, R is the radius of the hole, S is the distance between the holes, and Θ is the circular arc angle of the hole. arc is the circular arc angle of the hole.

4. The molding method according to claim 3, wherein In step one, the aspect ratio of the hole is determined to be 15 and S is 10 μm.

5. The forming method of any one of claims 1-4, wherein, In step two, the phase field dynamics model of the conductive polymer PMMA / CB under the action of thermal-electric coupling is established, and the total free energy equation of PMMA / CB under the action of thermal-electric coupling is: where G is the total free energy, is the order parameter, represents the volume free energy density, and the double-well potential function Since there are only two phases and and represents the density when there is only the corresponding substance, so where f0 is a constant; represents the surface energy density of the conductive polymer PMMA / CB, h is the surface energy coefficient, is the Laplace operator; represents the electric energy density of the rotating electric field, γ is the electric field-order parameter coupling strength constant, E(t) is the representation form of the rotating electric field, where E0 represents the electric field amplitude, ω is the rotation frequency, respectively represent the polarization in the x and y directions, represents the polarization direction; dr represents the volume integral element.

6. The molding method according to claim 5, wherein In step two, the internal ring-shaped micro-channel of PMMA / CB is realized by the driving force generated by atomic diffusion movement, which is determined by the volume free energy density, the surface free energy density and the rotating electric field energy density, and the chemical potential energy μ representing the driving force is: The Cahn-Hilliard nonlinear equation is derived from the surface atomic diffusion flux In partial differential equations embodied, expressed as: Wherein, M is the PMMA / CB atomic mobility; combined with formula (2), formula (3), the state evolution equation of order parameter The state evolution equation is derived as follows:

7. The molding method according to claim 1, wherein In step two, the heat field adopts a constant temperature heating table, and the temperature is 150℃.

8. The molding method according to claim 1, wherein In step two, the application of rotating electric field adopts orthogonal electrode method, the electrode ITO conductive glass is placed around PMMA / CB with four sides perpendicular to each other, the electrode spacing is 5mm, and the same oscillation signal of sine frequency and amplitude is applied through the signal source, the voltage is set to 5Vpp, and the frequency is 100Hz.

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