An apparatus and method for low voltage electrostatic microfluidic spinning

Abstract

The application discloses a device and method for low-voltage electrostatic microfluidic spinning, which mainly comprises a voltage application module, a heating module and a microfluidic module, and realizes the regulation of local pH, temperature and flow field respectively, and a sol-gel transition system sensitive to pH, temperature and flow field force can form a gel fiber through the device. ‑ When the device is used to prepare a mixed biomass polysaccharide gel fiber of KGM, the device realizes the enrichment of OH Ion and high temperature, and further induces the KGM molecules in the solution to remove acetyl functional groups and enhance the hydrogen bond effect to form a gel, realizes the speed regulation of spinning and the orientation of high molecular arrangement in the fiber through the microfluidic module. Compared with a traditional KGM fiber preparation method, a high-voltage electrostatic spinning method and an electric field preparation gel, the application does not need to add alkali to the whole KGM sol and carry out subsequent alkali removal, needs a lower voltage and can directly prepare a uniform fiber.

Description

Technical Field

[0001] This invention belongs to the field of spinning technology, specifically relating to an apparatus and method for low-voltage electrostatic microfluidic spinning. Background Technology

[0002] The gelation of konjac glucomannan (KGM) has long been a hot topic in academic research and industrial applications. The essence of KGM gelation by adding alkali is the removal of acetyl groups and the enhancement of hydrogen bonding.

[0003] Currently, the necessary condition for single KGM to form a gel is heating in the presence of an alkali to remove the acetyl groups on the KGM molecular chain, thereby forming an irreversible gel. After alkali treatment, the carbonyl vibration peak on the acetyl group is significantly weakened or disappears, and the deacetylated KGM molecules aggregate through hydrogen bonds to form a network structure, ultimately leading to gel formation (Kenji Maekaji, 1973, DOI:10.1080 / 00021369.1973.10861014). Deacetylation is generally carried out using alkalis (sodium hydroxide, sodium carbonate) as deacetyling agents to remove acetyl groups under solid-phase or heterogeneous conditions (Pang Jie, CN201710602554.2). However, using strong alkalis as deacetyling agents can cause other side reactions, making the reaction process difficult to control. After deacetylation of KGM with excess alkali, a dealkali removal step is also required, making the overall operation complex and causing resource waste and pollution. An electric field is used to electrotreat KGM, and under the action of the electric field, KGM self-assembly is induced, providing a convenient and pollution-free method for KGM deacetylation.

[0004] Currently, the main equipment used for preparing nanofibers is electrospinning and microfluidic air-jet spinning. Many products with different functions based on konjac glucomannan are prepared using electrospinning (Zheng Yafeng, CN106589442A; Pang Jie, CN108386120A; Zhang Dongzhi, CN115266912A). Electrospinning uses a microcomputer-controlled pump to automatically propel fluid, applying high pressure to the spinning solution at the needle tip. Under continuous high pressure, the spinning solution is ejected from the needle. Before reaching the receiving plate, the solvent in the ejected fluid rapidly evaporates or solidifies, while the charged fibers remain. Guided by electrostatic force, they fall onto the receiving plate and then stack layer by layer to form a nanofiber membrane (Zhang Hongwei, CN203247343U). The principle of existing electrospinning is that during the electrospinning process, the jetting device is filled with a charged polymer solution or molten liquid, and the jetting device is connected to the receiving plate with positive and negative electrodes, releasing high pressure. Under the action of an external electric field, polymer droplets held at the nozzle by surface tension accumulate surface charge under the induction of the electric field and are subjected to an electric force opposite to the direction of surface tension. As the electric field gradually increases, the droplets at the nozzle are stretched from a spherical shape to a cone shape, forming the so-called Taylor cone. When the electric field strength increases to a critical value, the electric force will overcome the surface tension of the liquid and spray out from the Taylor cone. The jet stream oscillates and becomes unstable under the action of a high electric field, generating irregular spiral motion with a very high frequency. In the high-speed oscillation, the jet stream is rapidly thinned and the solvent evaporates rapidly, eventually forming fibers with a diameter in the nanometer range, which are scattered randomly on the collection device to form a nonwoven fabric. Although electrospinning saves time and improves work efficiency to a certain extent, this method has the following disadvantages: (1) the spinning solution system must contain charged materials, which limits the application of neutral material systems; (2) electrospinning is carried out under high pressure, which poses certain dangers.

[0005] Compared to electrospinning, microfluidic air-jet spinning offers higher safety and a wider range of raw material selection. In continuous air-jet spinning devices, fibers do not become entangled due to cooling gas, improving fiber production efficiency (Wang Shaoyong, CN117005046A). Air-jet spinning utilizes microfluidic technology (such as microfluidic pumps and microfluidic chips) to create microchannels. By controlling the air pressure of the pump, the distance between the receiving device and the nozzle is adjusted to produce nanofibers with controllable dimensions. However, air-jet spinning still has shortcomings. For example, the spinning solution must be a readily solidified and volatile system, limiting the application of some non-volatile sol-gel systems; the equipment used in air-jet spinning remains relatively complex and expensive; and some fibers may fly out during the spinning process, resulting in resource waste.

[0006] Therefore, the present invention provides an apparatus and method for low-voltage electrostatic microfluidic spinning. Summary of the Invention

[0007] To overcome the above problems, the present invention aims to provide an apparatus and method for low-voltage electrostatic microfluidic spinning.

[0008] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0009] An apparatus for low-voltage electrostatic microfluidic spinning, comprising:

[0010] Extrusion module for containing spinning solution;

[0011] A voltage application module is used to apply voltage to the spinning solution in the extrusion module to create a local pH level in the extrusion module.

[0012] A heating module is used to apply localized heating to the spinning solution in the extrusion module;

[0013] The microfluidic module is used to adjust the extrusion speed of the spinning solution in the extrusion module.

[0014] As one possible implementation, the extrusion module is further selected as a syringe, which contains a spinning solution, wherein the spinning solution is a sol-gel transition material system that is sensitive to pH, temperature and flow field force.

[0015] As one possible implementation, the voltage application module further includes a DC power supply and two electrodes, one electrode inserted into the syringe cavity and the other electrode connected to the syringe needle tip. The two electrodes are respectively connected to the positive and negative terminals of the DC power supply. The electrode inside the syringe cavity and the electrode connected to the needle tip form a circuit. Utilizing the principle of water electrolysis, a redox reaction is induced at the anode and cathode. The electrode connected to the negative terminal of the DC power supply undergoes a reduction reaction, and the water around the cathode gains electrons to produce hydrogen and OH-. - This results in an alkaline environment around the cathode and an acidic environment around the positive electrode. The connection positions of the positive and negative electrodes of the power supply can be selected based on the pH level required for the material to form a gel.

[0016] As one possible implementation, the heating module further includes a heating resistor and a temperature regulator. The heating resistor is wound around the tip of the syringe needle, and the temperature regulator is electrically connected to the heating resistor for adjusting the heating temperature of the heating resistor.

[0017] As one possible implementation, the microfluidic module further utilizes a screw-driven pusher device, with the syringe mounted on it; the syringe propulsion speed is adjusted via the screw-driven pusher device. By adjusting the syringe propulsion speed, the microfluidic field provides velocity distribution control, which regulates the orientation of the polymer and is beneficial for improving fiber strength.

[0018] The present invention also provides a low-voltage electrostatic microfluidic spinning method, wherein the low-voltage electrostatic microfluidic spinning method applies the above-described apparatus for low-voltage electrostatic microfluidic spinning;

[0019] The low-voltage electrostatic microfluidic spinning method includes:

[0020] A konjac glucomannan material system was added to a syringe, and the electrode inserted into the syringe cavity was connected to the positive terminal of a DC power supply, while the electrode connected to the syringe needle tip was connected to the negative terminal of the DC power supply, causing OH groups to form around the needle tip electrode rod. - Ion enrichment region; the cathode at the needle tip position allows for the deacetylation of konjac glucomannan (KGM) within a small area, and after gelation, gel fibers are formed directly from the needle tip.

[0021] Local heating of the needle tip is achieved via a heating module. Under high temperature conditions, konjac glucomannan (KGM) undergoes deacetylation to form a thermally irreversible gel. Local heating achieves KGM deacetylation while avoiding resource waste. Subsequently, a microfluidic module propels the material in the syringe to form gel filaments. The heating and voltage modules control the OH- at the syringe needle outlet. - Ion enrichment and high temperature induce KGM molecules in the solution to lose acetyl functional groups, thereby forming a gel. The injection speed is adjusted by the microfluidic module, and the flow rate distribution provided by the microfluidic field regulates the orientation of the polymer, which is beneficial to improving the strength of the fiber.

[0022] As one possible implementation, the konjac glucomannan material system further comprises konjac glucomannan (KGM) and an electrolyte solution, wherein the electrolyte is a salt suitable for water electrolysis. The electrolyte solution induces redox reactions at both the anode and cathode. At the electrode connected to the negative terminal of the DC power supply, a reduction reaction occurs, and water around the cathode gains electrons to produce hydrogen and OH-. - This results in an alkaline environment around the cathode and an acidic environment around the positive electrode.

[0023] As a preferred embodiment, the konjac glucomannan material system preferably comprises 0.5-1.0 g / mL of konjac glucomannan and a 0.5-1.0% NaCl aqueous solution. Functional low-dimensional materials or particles (e.g., chitosan, carrageenan, sodium alginate, gelatin, xanthan gum, cellulose nanofibers, etc.) may also be added to the konjac glucomannan material system to achieve functionalized spinning.

[0024] In a preferred embodiment, the DC power supply is set to a voltage of 12-20V; the heating temperature at the needle tip is 80-90℃; and the syringe injection speed is 150-250uL / min.

[0025] In a preferred embodiment, the formed gel filaments are stretched by a winding module (which is an electric winding device) at a speed of 0.5-1.0 cm / s.

[0026] Existing electrospinning principles involve applying a high-voltage electrostatic charge of several thousand to tens of thousands of volts to a polymer solution or melt. Under the influence of the electric field, the droplet at the needle tip transforms from a spherical shape into a Taylor cone, extending from the tip of the cone to form fine filaments. This invention provides a low-voltage, environmentally friendly, and simple-to-operate electrostatic microfluidic spinning device and method. Utilizing the principle of water electrolysis, a positive electrode is inserted into the spinning solution, forming an electrical circuit with the negative electrode at the needle tip. By utilizing the positive and negative terminals of the power supply to generate different pH distributions, the sol-gel conversion system, sensitive to pH and flow field forces, is transformed into gel fibers using this device.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] Compared with existing traditional methods for preparing KGM filaments, high-voltage electrospinning, and electric field-based gel preparation, this invention eliminates the need for overall alkali addition to the KGM sol and subsequent alkali removal, requires lower voltage, and can directly prepare uniform filaments. Furthermore, the spinning solution system can be a material sensitive to pH, electric field, flow rate, and temperature, or it can be a mixed polymer solution containing KGM. Functionalized spinning can even be achieved by adding functional low-dimensional materials or particles to the konjac glucomannan (KGM) solution. Therefore, this invention offers advantages such as safe operation, simple method, resource conservation, and a wider range of material systems. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the device for low-voltage electrostatic microfluidic spinning according to the present invention;

[0031] Figure 2 Scanning electron microscope (SEM) images of the morphology and microstructure of KGM gel filaments at different magnifications;

[0032] Figure 3 These are actual photos of the device taken from different angles.

[0033] The labels in the attached diagram are as follows:

[0034] 1-Spinning solution; 2-Injector; 3-Screw pusher; 4-Electrode; 5-DC power supply; 6-Heating resistor; 7-Temperature regulator; 8-Electric winding device; 9-Gel filament. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] This invention provides an apparatus for low-voltage electrostatic microfluidic spinning, comprising:

[0037] The extrusion module contains the spinning solution; the voltage application module applies voltage to the spinning solution in the extrusion module to create a local pH level; the heating module locally heats the spinning solution in the extrusion module; and the microfluidic module regulates the extrusion speed of the spinning solution in the extrusion module.

[0038] The extrusion module uses syringe 2, which contains spinning solution 1. Spinning solution 1 is a sol-gel transition material system sensitive to pH, temperature, and flow field forces. Specifically, the sol-gel transition material system sensitive to pH, temperature, and flow field forces is a konjac glucomannan material system, which includes konjac glucomannan (KGM) and an electrolyte solution, wherein the electrolyte is a salt that can be used for water electrolysis.

[0039] Furthermore, functional low-dimensional materials or particles (such as chitosan, carrageenan, sodium alginate, gelatin, xanthan gum, cellulose nanofibers, etc.) can be added to the konjac glucomannan material system to achieve functionalized spinning.

[0040] The voltage application module includes a DC power supply 5 and two electrodes 4. One electrode 4 is inserted into the cavity of the syringe 2, and the other electrode is connected to the needle tip of the syringe 2. The two electrodes 4 are respectively connected to the positive and negative terminals of the DC power supply 5. The electrode 4 in the cavity of the syringe 2 and the electrode connected to the needle tip form a circuit. Utilizing the principle of water electrolysis, an oxidation-reduction reaction is induced at the anode and cathode. The electrode connected to the negative terminal of the DC power supply undergoes a reduction reaction, and the water around the cathode gains electrons to produce hydrogen gas and OH-. - This results in an alkaline environment around the cathode and an acidic environment around the positive electrode. The connection positions of the positive and negative electrodes of the power supply can be selected based on the pH level required for the material to form a gel.

[0041] The heating module includes a heating resistor 6 and a temperature regulator 7. The heating resistor 6 is wound around the tip of the syringe 2 needle, and the temperature regulator 7 is electrically connected to the heating resistor 6 to adjust its heating temperature. Localized heating achieves gelation of the spinning solution while avoiding resource waste.

[0042] The microfluidic module uses a screw pusher device 3 (an existing device), and the syringe 2 is mounted on the screw pusher device 3. The advancement speed of the syringe 3 is adjusted through the screw pusher device. By adjusting the advancement speed of the syringe through the microfluidic module, the flow field provides velocity distribution control, which regulates the orientation of the polymer and is beneficial to improving the strength of the fiber.

[0043] The voltage application module, heating module, and microfluidic module of this invention respectively enable localized control of pH, temperature, and flow field. Sol-gel transition systems sensitive to pH, temperature, and flow field forces can be formed into gel fibers using this device.

[0044] As a further improvement, the device for low-voltage electrostatic microfluidic spinning also includes a winding module for stretching and collecting the gel filament 9; wherein the winding module may be an electric winding device.

[0045] Example 1

[0046] See attached document Figure 1 As shown, this embodiment provides an apparatus for low-voltage electrostatic microfluidic spinning, which includes: a syringe 2 (including a needle), a screw pusher 3, an electrode 4, a DC power supply 5, a heating resistor 6, a temperature regulator 7, and an electric winding device 8.

[0047] The syringe 2 contains a spinning solution 1 (a mixture of KGM and electrolyte solution). An electrode 4 is inserted into the syringe 2 and connected to the positive terminal of a DC power supply 5. Another electrode 4 is connected to the needle tip of the syringe 2 and to the negative terminal of the DC power supply 5. The inserted electrode (positive terminal) and the electrode connected to the needle tip (negative terminal) form a circuit, generating OH groups around the needle tip electrode rod. -Ion enrichment region. A heating resistor 6 is wound around the tip of syringe 2. A temperature regulator 7 is electrically connected to the heating resistor 6 to control its heating temperature. During use, the temperature regulator 7 controls the heating resistor 6 to a constant temperature, creating a constant high-temperature region that induces KGM molecules in the solution to lose acetyl functional groups and enhances hydrogen bonding, thereby forming a gel. Syringe 2 is mounted on a screw pusher 3, which adjusts the speed of syringe 2. During use, the screw pusher 3 controls the spinning rate and directs the arrangement of polymers in the fiber. This device eliminates the need for overall alkali addition to the KGM sol and subsequent alkali removal. The push of syringe 2 helps improve fiber strength, forming KGM gel filaments 9. The formed gel filaments 9 are stretched and collected by an electric reel 8.

[0048] This embodiment also provides a low-voltage electrostatic microfluidic spinning method, which uses the above-described apparatus for low-voltage electrostatic microfluidic spinning, and includes:

[0049] Add the konjac glucomannan material system to syringe 2, wherein the konjac glucomannan material system contains 0.5-1.0 g / mL of konjac glucomannan and 0.5-1.0% NaCl aqueous solution;

[0050] In this embodiment, the konjac glucomannan material system was prepared by dissolving 1g of KGM in 100mL of 1% NaCl aqueous solution, stirring for 30min, and then letting it stand overnight to allow it to fully swell.

[0051] The DC power supply 5 is set to a DC voltage of 12-20V, and the heating resistor 6 is set to a temperature of 80-90℃ to locally heat the tip of the syringe 2. The lead screw pusher 3 extrudes the material in the syringe at a pushing speed of 150-250uL / min to form gel filaments 9. The electric retractor 8 collects the gel filaments 9, and the drawing speed of the electric retractor 8 is 0.5-1.0cm / s.

[0052] See attached document Figure 2 As shown, the surface morphology of the lyophilized hydrogel was characterized using SEM. Small protruding particles were observed on the surface of the pure KGM gel filaments, which may be due to partial aggregation of KGM particles during the dissolution process. Furthermore, the KGM gel filaments were uniform in size and diameter, and a very fine continuous structure could be observed.

[0053] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An apparatus for low-voltage electrostatic microfluidic spinning, characterized in that, include: Extrusion module for containing spinning solution; The extrusion module is a syringe containing a spinning solution, which is a sol-gel conversion material system that is sensitive to pH, temperature and flow field force. A voltage application module is used to apply voltage to the spinning solution in the extrusion module to create a local pH level in the extrusion module. The voltage application module includes a DC power supply and two electrodes, one of which is inserted into the cavity of the syringe and the other electrode is connected to the tip of the syringe needle. The two electrodes are respectively connected to the positive and negative terminals of the DC power supply. The electrode in the syringe cavity and the electrode connected to the tip of the syringe form a circuit. A heating module is used to locally heat the spinning solution in the extrusion module; the heating module includes a heating resistor wound around the tip of the syringe needle; The microfluidic module is used to adjust the extrusion speed of the spinning solution in the extrusion module.

2. The apparatus for low-voltage electrostatic microfluidic spinning according to claim 1, characterized in that, The heating module also includes a temperature regulator, which is electrically connected to the heating resistor and is used to adjust the heating temperature of the heating resistor.

3. The apparatus for low-voltage electrostatic microfluidic spinning according to claim 1, characterized in that, The microfluidic module uses a lead screw pusher device, and the syringe is mounted on the lead screw pusher device; the syringe advance speed is adjusted by the lead screw pusher device.

4. A low-voltage electrostatic microfluidic spinning method, characterized in that, The low-voltage electrostatic microfluidic spinning method uses the apparatus for low-voltage electrostatic microfluidic spinning as described in claim 2. The low-voltage electrostatic microfluidic spinning method includes: A konjac glucomannan material system was added to a syringe, and the electrode inserted into the syringe cavity was connected to the positive terminal of a DC power supply, while the electrode connected to the syringe needle tip was connected to the negative terminal of the DC power supply, causing OH groups to form around the needle tip electrode rod. - Ion enrichment region; The needle tip is locally heated by a heating module, and the material in the syringe is extruded to form a gel filament by a microfluidic module.

5. The low-voltage electrostatic microfluidic spinning method according to claim 4, characterized in that, The konjac glucomannan material system comprises konjac glucomannan and an electrolyte solution, wherein the electrolyte is a salt that can be used for water electrolysis.

6. The low-voltage electrostatic microfluidic spinning method according to claim 5, characterized in that, The konjac glucomannan material system comprises 0.5-1.0 g / mL konjac glucomannan and 0.5-1.0% NaCl aqueous solution.

7. The low-voltage electrostatic microfluidic spinning method according to claim 6, characterized in that, The DC power supply is set to a voltage of 12-20V; the heating temperature at the needle tip is 80-90℃; and the syringe advance speed is 150-250uL / min.

8. The low-voltage electrostatic microfluidic spinning method according to claim 6, characterized in that, The formed gel filaments are pulled and stretched by a winding module at a speed of 0.5-1.0 cm / s.

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