3D microfluidic printing equipment and method for preparing porous piezoelectric hydrogel

Abstract

The invention relates to 3D micro-fluidic printing equipment which comprises a base, a supporting seat and a supporting arm are installed on the upper surface of the base, a bottom plate used for containing a printed product is arranged on the upper surface of the supporting seat, a spray head support is movably arranged on the front side of the supporting arm, and a 3D micro-fluidic printing spray head is fixedly connected to the bottom end of the spray head support. And a boss is arranged on the front side of the 3D micro-fluidic chip. According to the invention, gas and a material are respectively introduced into the 3D micro-fluidic chip through the inlet A and the inlet B, and after the gas and the material in the bubble generation layer are converged, the material containing a large number of bubbles is generated and is used for printing the porous piezoelectric gel; by adjusting the depths of bolts in a continuous-phase threaded hole A, a continuous-phase threaded hole B, a continuous-phase threaded hole C, a continuous-phase threaded hole D, a dispersed-phase threaded hole A, a dispersed-phase threaded hole B, a dispersed-phase threaded hole C and a dispersed-phase threaded hole D, the pressure of gas and the flow of materials are controlled, and porous piezoelectric gels with different porosities can be prepared. And the piezoelectric material has different piezoelectric properties.

Description

Technical Field

[0001] The present invention relates to the technical field of porous piezoelectric hydrogel material preparation equipment, and in particular to a 3D microfluidic printing device and a method for preparing porous piezoelectric hydrogel. Background Art

[0002] Three-dimensional porous gel materials are widely used in flexible electronic sensors, biological scaffolds and other fields due to their excellent mechanical properties such as ultra-high strength / density ratio, super strong compression resilience, high porosity and energy absorption capacity. With the increasing demand for three-dimensional porous gel materials, methods such as bubble method, solvent method, template method, gel method and 3D printing have been used to prepare three-dimensional porous materials. However, these methods still have shortcomings in the morphology and parameter control of three-dimensional porous gel materials and need further development.

[0003] 3D printing technology provides an ideal way for shape-controlled manufacturing of metal materials and polymer materials by stacking point-to-point or layer-to-layer additives of materials. A typical 3D printing system usually consists of a nozzle and a 3D motion system. The pre-printed material is extruded to the base surface in a liquid state through the nozzle and forms a patterned printed structure with the three-dimensional motion system. With the rapid development of 3D printing technology, the scale of the prepared device structure has also developed from micron to submicron and nanometer. Microsensors, flexible electronics, microfluidic chips, bioscaffolds, etc. manufactured using 3D printing technology have been widely used in many fields such as biology, medicine, machinery, and electronics. However, 3D printing technology shows great advantages in controlling the external morphology of materials, but it still has shortcomings in manufacturing materials with micro-nano porous structures inside.

[0004] In order to solve the above problems, the present invention proposes a 3D microfluidic printing device and a method for preparing porous piezoelectric hydrogel. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art, meet practical needs, and provide a 3D microfluidic printing device and a method for preparing porous piezoelectric hydrogel to solve the above technical problems.

[0006] In order to achieve the purpose of the present invention, the technical solution adopted by the present invention is: A 3D microfluidic printing device comprises a base, wherein a support base and a support arm are respectively installed on the upper surface of the base, wherein a bottom plate for placing printed products is arranged on the upper surface of the support base, a nozzle bracket is movably arranged on the front side of the support arm, a 3D microfluidic printing nozzle is fixedly connected to the bottom end of the nozzle bracket, the 3D microfluidic printing nozzle comprises a 3D microfluidic chip and a chip connecting plate for fixing the 3D microfluidic chip to the nozzle bracket, a boss is arranged on the front side of the 3D microfluidic chip, and the 3D The microfluidic chip has an inlet A, an inlet B and an outlet A, the bottom end of the outlet A is coaxially and interference-fittedly connected with a nozzle, the 3D microfluidic chip is sequentially provided with six layers of microchannels along the radial direction of the dispersed phase threaded hole A from the front side of the boss, the six layers of microchannels are respectively a top layer, a dispersed phase inlet channel layer, a bubble generation layer, a continuous phase inlet channel layer, an outlet collection layer and a bottom layer, the gas and material respectively introduced into the inlet A and the inlet B merge in the bubble generation layer to generate a material containing a large number of bubbles for printing porous piezoelectric gel.

[0007] The present invention also discloses a method for preparing porous piezoelectric hydrogel based on the above 3D microfluidic printing device, comprising the following steps: Step 1, prepare a polyvinyl alcohol composite hydrogel solution, load the prepared polyvinyl alcohol composite hydrogel solution into a nitrogen pressure injection pump reservoir, connect the syringe to the connecting tube A through a Teflon hose, and then plug it into the inlet A; Step 2, connect the nitrogen pressure injection pump to the connecting pipe B through the Teflon hose, and then plug it into the inlet B; Step 3, turn on the low-temperature coolant circulation pump and the quick freezing device switch, and wait for the metal surface temperatures of the first refrigeration plate, the second refrigeration plate, and the third refrigeration plate to drop to below zero and stabilize; Step 4, screw four M2 bolts into continuous phase threaded hole A, continuous phase threaded hole B, continuous phase threaded hole C and continuous phase threaded hole D respectively, so that the continuous phase threaded hole A, continuous phase threaded hole B, continuous phase threaded hole C and continuous phase threaded hole D remain in a closed state, and the screwing depth does not exceed the bubble generation layer, screw the other four M2 bolts into dispersed phase threaded hole A, dispersed phase threaded hole B, dispersed phase threaded hole C and dispersed phase threaded hole D respectively, so that the dispersed phase threaded hole A, dispersed phase threaded hole B, dispersed phase threaded hole C and dispersed phase threaded hole D remain in a closed state, and the screwing depth does not exceed the continuous phase distribution channel in the top layer, turn on the nitrogen pressure injection pump switch, and make the polyvinyl alcohol composite hydrogel solution drip continuously from the nozzle of the 3D microfluidic printing nozzle; Step 5, turn on the nitrogen pressure injection pump switch to stably generate bubbles in the T-shaped channel of the bubble generation layer, and then adjust the screwing depth of the M2 bolts in the continuous phase threaded hole A, the continuous phase threaded hole B, the continuous phase threaded hole C, the continuous phase threaded hole D, the dispersed phase threaded hole A, the dispersed phase threaded hole B, the dispersed phase threaded hole C and the dispersed phase threaded hole D to change the degree of shielding of the channels by the above bolts, so as to achieve the effect of fine-tuning the pressure in the channel, so that the size of the bubbles generated inside the T-shaped channels of the circular array is uniform; Step 6, after the polyvinyl alcohol composite hydrogel solution containing a large number of bubbles drips from the nozzle, the 3D microfluidic printing nozzle is moved to 10 mm above the upper surface of the first cooling plate using the control software, the high-voltage power switch is turned on, and the high-voltage power voltage is gradually increased to reduce the droplet size to the desired state; Step 7, writing a nozzle movement control program of the required printing pattern through the control software, and controlling the 3D microfluidic printing nozzle to cover the surface of the first refrigeration plate repeatedly, so that the polyvinyl alcohol composite hydrogel solution containing bubbles drips onto the first refrigeration plate and freezes quickly; Step 8, after the previous layer of polyvinyl alcohol composite hydrogel solution is completely frozen, the movement control program of the 3D microfluidic printing nozzle is executed again to print a new layer of polyvinyl alcohol hydrogel on the previous layer of polyvinyl alcohol composite hydrogel; Step 9, repeating step 7 multiple times to form a frozen three-dimensional porous hydrogel structure; Step 10, placing the frozen three-dimensional porous hydrogel in a -20°C refrigerator, freezing for 12 hours, and then taking it out and placing it at room temperature for 1 hour; Step 11, repeating step 9 multiple times, gelling the three-dimensional porous hydrogel through freeze-thaw cycles to form a soft and elastic three-dimensional porous piezoelectric hydrogel.

[0008] Beneficial effects: In the present invention, gas and material are respectively introduced into the 3D microfluidic chip through inlet A and inlet B, and after the gas and material in the bubble generation layer merge, a material containing a large number of bubbles is generated for printing porous piezoelectric gel. By adjusting the depth of bolts in continuous phase threaded holes A, continuous phase threaded holes B, continuous phase threaded holes C and continuous phase threaded holes D and dispersed phase threaded holes A, dispersed phase threaded holes B, dispersed phase threaded holes C and dispersed phase threaded holes D, the gas pressure and the flow rate of the material are controlled, so that porous piezoelectric gels with different porosities and different piezoelectric properties can be prepared. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention; Figure 2 It is a schematic diagram of the three-dimensional structure of the 3D microfluidic printing nozzle of the present invention; Figure 3Schematic diagram of the three-dimensional structure of the 3D microfluidic chip of the present invention; Figure 4 This is a side view structural schematic diagram of the 3D microfluidic chip of the present invention; Figure 5 For the present invention Figure 4 Schematic diagram of the cross-sectional structure along line AA; Figure 6 For the present invention Figure 5 Schematic diagram of the cross-sectional structure along the CC line; Figure 7 This is a schematic diagram of the front view structure of the 3D microfluidic chip of the present invention; Figure 8 For the present invention Figure 7 The schematic diagram of the cross-sectional structure along the BB line; Fig. 9 The second schematic diagram of the side view structure of the 3D microfluidic chip of the present invention; Fig.10 For the present invention Fig. 9 Schematic diagram of the cross-sectional structure along the DD line; Fig.11 For the present invention Fig.10 Schematic diagram of the cross-sectional structure along line EE; Fig.12 This is the second schematic diagram of the structure of the 3D microfluidic chip of the present invention; Fig.13 For the present invention Fig.12 Schematic diagram of the cross-sectional structure along the FF line; Fig.14 The third schematic diagram of the side view structure of the 3D microfluidic chip of the present invention; Fig.15 For the present invention Fig.14 Schematic diagram of the cross-sectional structure along the GG line; Fig.16 The third schematic diagram of the front view structure of the 3D microfluidic chip of the present invention; Fig.17 For the present invention Fig.16 A schematic diagram of the cross-sectional structure along the HH line; Fig.18 The fourth schematic diagram of the front view structure of the 3D microfluidic chip of the present invention; Fig.19 For the present invention Fig.18 The first schematic diagram of the cross-sectional structure along the JJ line; Fig. 20 For the present invention Fig.18 The second schematic diagram of the cross-sectional structure along the JJ line; Fig.21 This is the second schematic diagram of the three-dimensional structure of the rapid freezing device of the present invention.

[0010] The reference numerals are as follows: 1. Base; 2. Support seat; 2-1. First slide; 3. Bottom plate; 4. First slider; 5. Support arm; 5-1. Second slide; 6. Moving plate; 6-1. Second slider; 6-2. Third slide; 7. Nozzle bracket; 8. Nozzle connecting plate; 9. 3D microfluidic printing nozzle; 10. Rapid freezing device; 11. Insulation shell; 12. Microfluidic chip; 12-1. Chip positioning hole A; 12-2. Continuous phase threaded hole D; 12-3. Dispersed phase threaded hole D; 12-4. Continuous phase threaded hole C; 12-5, outlet A; 12-5A, outlet A channel; 12-6, chip positioning hole B; 12-7, dispersed phase threaded hole C; 12-8, continuous phase threaded hole B; 12-9, dispersed phase threaded hole B; 12-10, continuous phase threaded hole A; 12-11, dispersed phase threaded hole A; 12-12, inlet B; 12-12B, continuous phase channel; 12-13, inlet A; 12-13A, dispersed phase channel; 13, chip connecting plate; 13-1, bracket connecting hole A, 13-2 , bracket connection hole B; 13-3, bracket connection hole C; 13-4, bracket connection hole D; 14, nozzle; 15-1, wire clamp A; 15-2, wire clamp B; 16, high voltage power supply positive wire; 17-1, connecting tube A; 17-2, connecting tube B; 18, bubble generation layer; 18-1, first outlet channel; 18-2, first dispersed phase inlet channel; 18-3, second outlet channel; 18-4, second dispersed phase inlet channel; 18-5, second outlet channel; 18-6, first Three dispersed phase inlet channels; 18-7, fourth outlet channel; 18-8, fourth dispersed phase inlet channel; 18-9, straight channel; 18-10, arc channel; 18-11, connecting channel; 19, continuous phase inlet channel layer; 20, outlet collection layer; 20-1, cross channel; 20-2, through hole; 21, bottom layer; 21-1, direct channel; 22, top layer; 22-1, continuous phase distribution channel; 22-2, vertical channel; 23, dispersed phase inlet channel layer; 23-1, oblique channel. DETAILED DESCRIPTION

[0011] The following is combined with Figure 1-21 The present invention is further described with examples: like Figure 1As shown, a 3D microfluidic printing device includes a base 1, a support seat 2 and a support arm 5 are respectively installed on the upper surface of the base 1, a first slide groove 2-1 is opened on the upper surface of the support seat 2, the first slide groove 2-1 is arranged along the Y axis, the inner bottom wall of the first slide groove 2-1 is slidably connected with a first slider 4, the upper surface of the first slider 4 is fixedly connected with a bottom plate 3 through a leveling bolt, an insulation shell 11 is horizontally installed at the center of the upper surface of the bottom plate 3, a quick freezing device 10 is horizontally installed at the center of the inner part of the insulation shell 11, a second slide groove 5-1 is opened on the front of the support arm 5, and the second slide groove 5-1 is arranged along the X-axis, the inner bottom wall of the second slide groove 5-1 is slidably connected to the second slider 6-1, the front end of the second slider 6-1 is fixedly connected to the movable plate 6, the side of the movable plate 6 away from the second slider 6-1 is provided with a third slide groove 6-2, the third slide groove 6-2 is arranged along the Z-axis, the inner wall of the third slide groove 6-2 is slidably connected to the nozzle bracket 7, the end of the nozzle bracket 7 away from the third slide groove 6-2 is fixedly connected to the nozzle connecting plate 8 by four M4 bolts and hexagonal nuts, and the bottom end of the nozzle bracket 7 is fixedly connected to the 3D microfluidic printing nozzle 9 by four M2 bolts and nuts.

[0012] like Figure 2 As shown, the 3D microfluidic printing nozzle 9 includes a 3D microfluidic chip 12 and a chip connecting plate 13 for fixedly connecting the 3D microfluidic chip 12 to the nozzle bracket 7 .

[0013] like Figure 2 and Figure 3 As shown, the diagonals of the 3D microfluidic chip 12 are respectively provided with a chip positioning hole A12-1 and a chip positioning hole B12-6, a boss is provided on the front side of the 3D microfluidic chip 12, and the front side of the boss is in a cross shape and is respectively provided with a dispersed phase threaded hole A12-11, a dispersed phase threaded hole B12-9, a dispersed phase threaded hole C12-7 and a dispersed phase threaded hole D12-3, the front side of the boss is in an X shape and is respectively provided with a continuous phase threaded hole A12-10, a continuous phase threaded hole B12-8, a continuous phase threaded hole C12-4 and a continuous phase threaded hole D12-2, an inlet A12-13 and an inlet B12-12 are respectively provided along the vertical direction on the side of the 3D microfluidic chip 12 close to the chip positioning hole A12-1, and an outlet A12-5 is provided along the vertical direction on the side of the 3D microfluidic chip 12 close to the chip positioning hole B12-6.

[0014] like Figure 2 and Figure 3As shown, the chip connection plate 13 is fixedly connected to the chip positioning hole A12-1 and the chip positioning hole B12-6 by two M2 bolts, the two sides of the chip connection plate 13 are respectively provided with a bracket connection hole A13-1 and a bracket connection hole B13-2, the top of the chip connection plate 13 is respectively provided with a bracket connection hole C13-3 and a bracket connection hole D13-4, the chip connection plate 13 is fixedly connected to the bottom end of the nozzle bracket 7 through the bracket connection hole A13-1, the bracket connection hole B13-2, the bracket connection hole C13-3, and the bracket connection hole D13-4, the bottom end of the outlet A12-5 is coaxially and interference fit connected with the nozzle 14, and the outlet A wire clamp A15-1 and a wire clamp B15-2 are provided at the connection between A12-5 and the nozzle 14. The wire clamp A15-1 and the wire clamp B15-2 are fastened by bolts. The wire clamp A15-1 and the wire clamp B15-2 cooperate to form an intermediate circular hole coaxially matched with the nozzle 14, and a high-voltage power supply positive wire 16 is provided in the intermediate circular hole. The nozzle 14 is connected to the high-voltage power supply positive wire 16. The inlet A12-12 and the inlet B12-13 are coaxially matched and interference-connected with a connecting pipe A17-1 and a connecting pipe B17-2. The outer sides of the connecting pipe A17-1 and the connecting pipe B17-2 are both covered with Teflon hoses.

[0015] like Figure 4 As shown, the 3D microfluidic chip 12 is provided with six layers of microchannels in sequence along the radial direction of the dispersed phase threaded hole A12-11 from the front side of the boss, and the six layers of microchannels are respectively a top layer 22, a dispersed phase inlet channel layer 23, a bubble generation layer 18, a continuous phase inlet channel layer 19, an outlet collection layer 20 and a bottom layer 21.

[0016] like Figure 4-Figure 8As shown, the bubble generation layer 18 is provided with four T-shaped channels arranged in a circular array, each T-shaped channel includes a straight channel 18-9 and an arc-shaped channel 18-10 connected to the straight channel, one end of the four straight channels 18-9 overlaps and forms an overlap point, and a connecting channel 18-11 extending to the continuous inlet channel layer 19 is opened at the overlap point, and the other ends of the four straight channels 18-9 are respectively provided with a first outlet channel 18-1, a second outlet channel 18-3, a third outlet channel 18-5 and a fourth outlet channel 18-7 in a vertical plane, and the four T-shaped channels are arranged in a circular array with the overlap point as a circle, one end of the four arc-shaped channels 18-10 is connected to the corresponding straight channel 18-9, and the four arc-shaped channels 18-10 are respectively connected to the corresponding straight channel 18-9, and the four arc-shaped channels 18-10 are respectively connected to the corresponding straight channel 18-9. The other end is respectively provided with a first dispersed phase inlet channel 18-2, a second dispersed phase inlet channel 18-4, a third dispersed phase inlet channel 18-6 and a fourth dispersed phase inlet channel 18-8 in a vertical plane. The first dispersed phase inlet channel 18-2 is connected with the dispersed phase threaded hole B12-9, the second dispersed phase inlet channel 18-4 is connected with the dispersed phase threaded hole C12-7, the third dispersed phase inlet channel 18-6 is connected with the dispersed phase threaded hole D12-3, the fourth dispersed phase inlet channel 18-8 is connected with the dispersed phase threaded hole A12-11, and the continuous phase threaded hole A12-10, the continuous phase threaded hole B12-8, the continuous phase threaded hole C12-4 and the continuous phase threaded hole D12-2 respectively pass through the corresponding straight channels 18-9.

[0017] like Figure 4-Figure 6 As shown, the continuous phase inlet channel layer 19 is the next layer of microchannels adjacent to the bubble generation layer 18, and a continuous phase channel 12-12B is arranged in the continuous phase inlet channel layer 19, the connecting channel 18-11 is connected with the outlet end of the continuous phase channel 12-12B, the inlet end of the continuous phase channel 12-12B is connected with the inlet B12-12, and the continuous phase threaded hole A12-10, the continuous phase threaded hole B12-8, the continuous phase threaded hole C12-4 and the continuous phase threaded hole D12-2 extend to the rear side of the continuous phase inlet channel layer 19.

[0018] like Figure 9-13 As shown, the outlet collection layer 20 is the next layer of microchannels adjacent to the continuous phase inlet channel layer 19, and a windmill-shaped cross channel 20-1 is arranged in the outlet collection layer 20, and the first outlet channel 18-1, the second outlet channel 18-3, the third outlet channel 18-5 and the fourth outlet channel 18-7 are connected to the ends of the cross channel 20-1, and a through hole 20-2 extending to the bottom layer 21 is opened at the center of the cross channel 20-1.

[0019] like Figure 12-13As shown, the bottom layer 21 is the next layer of microchannels adjacent to the outlet collection layer 20, and an outlet A channel 12-5A is arranged in the bottom layer 21, and the through hole 20-2 is connected to the inlet end of the outlet A channel 12-5A, and a direct channel 21-1 is arranged at the outlet end of the outlet A channel 12-5A, and the direct channel 21-1 is connected to the center of the outlet A12-5.

[0020] like Figure 14-15 As shown, the top layer 22 is a layer of microchannels on the front end face of the boss of the 3D microfluidic chip 12, and a cross-shaped continuous phase distribution channel 22-1 is arranged in the top layer 22, and the dispersed phase threaded hole A12-11, the dispersed phase threaded hole B12-9, the dispersed phase threaded hole C12-7 and the dispersed phase threaded hole D12-3 respectively vertically penetrate the continuous phase distribution channel 22-1, and the dispersed phase threaded hole A12-11, the dispersed phase threaded hole B12-9, the dispersed phase threaded hole C12-7 and the dispersed phase threaded hole D12-3 are respectively connected with the four ends of the continuous phase distribution channel 22-1, and the continuous phase threaded hole A12-10, the continuous phase threaded hole B12-8, the continuous phase threaded hole C12-4 and the continuous phase threaded hole D12-2 penetrate the top layer 22 and extend to the front end face of the boss, and a vertical channel 22-2 extending to the dispersed phase inlet channel layer 23 is opened at the center of the continuous phase distribution channel 22-1.

[0021] like Figure 16-Figure 17 As shown, the dispersed phase inlet channel layer 23 is located between the top layer 22 and the bubble generation layer 18, and a dispersed phase channel 12-13A is arranged in the dispersed phase inlet channel layer 23. The vertical channel 22-2 is connected to the outlet end of the dispersed phase channel 12-13A, and an inclined channel 23-1 is arranged at the inlet end of the dispersed phase channel 12-13A, and the inclined channel 23-1 is connected to the inlet A12-13.

[0022] The continuous phase threaded hole A12-10, the continuous phase threaded hole B12-8, the continuous phase threaded hole C12-4 and the continuous phase threaded hole D12-2 play the role of sealing, fine-tuning the channel pressure and facilitating cleaning. When the bolt is screwed in but the depth does not exceed the bubble generation layer 18, the continuous phase threaded hole A12-10, the continuous phase threaded hole B12-8, the continuous phase threaded hole C12-4 and the continuous phase threaded hole D12-2 can be sealed without leakage, and at the same time, when the hydrogel solution is passed into the inlet B12-12, the hydrogel solution can pass through the connection passage in the bubble generation layer 18. The liquid flows through the straight channel 18-11. When the screw-in depth of the bolt is located in the bubble generation layer 18, the screw-in depth of the bolt can be adjusted to adjust the degree of blocking of the straight channel 18-9 of the four T-channels in the bubble generation layer 18, so as to achieve the effect of fine-tuning the flow rate. When the bolt is fully screwed in, the straight channel 18-9 corresponding to the above-mentioned continuous phase threaded hole A12-10, continuous phase threaded hole B12-8, continuous phase threaded hole C12-4 and continuous phase threaded hole D12-2 can be closed. When using alcohol to clean the chip, all bolts are removed to facilitate the discharge of impurities in the channel.

[0023] The dispersed phase threaded holes A12-11, B12-9, C12-7 and D12-3 play the role of sealing, fine-tuning the channel pressure and facilitating cleaning. When the bolts are screwed in but the depth does not exceed the continuous phase distribution channel 22-1, the dispersed phase threaded holes A12-11, B12-9, C12-7 and D12-3 can be sealed without leakage, and at the same time, it is ensured that when nitrogen is introduced into the inlet A12-13, nitrogen can be passed from the continuous phase distribution channel 22 -1 passes through the dispersed phase threaded hole B12-9, the dispersed phase threaded hole C12-7, the dispersed phase threaded hole D12-3 and the dispersed phase threaded hole A12-11 to enter the four arc-shaped channels 18-10. When the bolt is screwed into the top layer 22, the depth of the bolt can be adjusted to adjust the degree of blocking of the continuous phase distribution channel 22-1 in the top layer 22, so as to achieve the effect of fine-tuning the flow rate. When the bolt is fully screwed in, the continuous phase distribution channel 22-1 can be closed. When using alcohol to clean the chip, all bolts should be removed to facilitate the discharge of impurities in the channel.

[0024] The 3D microfluidic chip 12 is an integrated structure. The material of the 3D microfluidic chip 12 is resin. The 3D microfluidic chip 12 is formed in one step by 3D printing technology.

[0025] like Fig.21As shown, the rapid freezing device 10 includes a freezing device bracket 10-9, and the freezing device bracket 10-9 is provided with a first refrigeration plate positioning groove 10-8 in the horizontal direction. The first refrigeration plate positioning groove 10-8 is fixedly connected with a first refrigeration plate 10-1 in the horizontal direction. The first refrigeration plate 10-1 is sequentially composed of a metal plate, a semiconductor refrigeration sheet, a water cooling head and a bayonet and is fixed and clamped by bolts, wherein the inlet and outlet of the water cooling head are respectively connected to the liquid outlet and inlet of the low-temperature coolant circulation pump through a rubber hose, and the metal plate smooth side of the first refrigeration plate 10-1 is horizontally upward A second refrigeration plate slot 10-2 and a third refrigeration plate slot 10-6 are respectively provided on both sides of the interior of the refrigeration device bracket 10-9, a second refrigeration plate 10-3 is vertically clamped in the second refrigeration plate slot 10-2, a third refrigeration plate 10-5 is vertically clamped in the third refrigeration plate slot 10-6, the structural composition of the second refrigeration plate 10-3 and the third refrigeration plate 10-5 is the same as the first refrigeration plate 10-1, and the metal plate side of the second refrigeration plate 10-3 is opposite to the third refrigeration plate 10-5, and a high-voltage power supply negative electrode wire 10-4 is welded on the back of the first refrigeration plate 10-1.

[0026] The present invention also discloses a method for preparing a porous piezoelectric gel material based on a 3D microfluidic printing device, comprising the following steps: Step 1, prepare a polyvinyl alcohol composite hydrogel solution, load the prepared polyvinyl alcohol composite hydrogel solution into the nitrogen pressure injection pump reservoir, connect the syringe to the connecting tube A17-1 through a Teflon hose, and then plug it into the inlet A12-2; Step 2, connect the nitrogen pressure injection pump to the connecting pipe B17-2 through the Teflon hose, and then plug it into the inlet B12-13; Step 3, turn on the low-temperature coolant circulation pump and the quick freezing device 10 switch, and wait for the metal surface temperatures of the first refrigeration plate 10-1, the second refrigeration plate 10-3 and the third refrigeration plate 10-5 to drop to below zero and stabilize; Step 4, screw four M2 bolts into the continuous phase threaded hole A12-10, the continuous phase threaded hole B12-8, the continuous phase threaded hole C12-4 and the continuous phase threaded hole D12-2 respectively, so that the continuous phase threaded hole A12-10, the continuous phase threaded hole B12-8, the continuous phase threaded hole C12-4 and the continuous phase threaded hole D12-2 remain in a closed state, and the screwing depth does not exceed the bubble generation layer 18, and screw another four M2 bolts into the dispersed phase threaded hole A12-11, the dispersed phase threaded hole B12-9, the dispersed phase threaded hole C12-7 and the dispersed phase threaded hole D12-3 respectively, so that the dispersed phase threaded hole A12-11, the dispersed phase threaded hole B12-9, the dispersed phase threaded hole C12-7 and the dispersed phase threaded hole D12- 3. Keep the closed state, and screw into the continuous phase distribution channel 22-1 in the top layer 22 to a depth not exceeding that of the top layer 22. Turn on the nitrogen pressure injection pump switch to allow the polyvinyl alcohol composite hydrogel solution to flow to the straight channel 18-9 of the T-shaped channel after passing through the inlet B12-12, the continuous phase channel 12-12B, and the connecting channel 18-11 in sequence. Then, the polyvinyl alcohol composite hydrogel solution enters the cross channel 20-1 from the first outlet channel 18-1, the second outlet channel 18-3, the third outlet channel 18-5, and the second outlet channel 18-7. After continuing to flow, it converges at the through hole 20-2 and passes through the outlet A channel 12-5A and the direct connection channel 21-1 in sequence to enter the outlet A12-5, and continuously drips from the nozzle 14 of the 3D microfluidic printing nozzle 9. Step 5, turn on the nitrogen pressure injection pump switch to allow the gas to enter the 3D microfluidic chip 12, adjust the injection pump injection speed and the air pump pressure, and the gas enters the continuous phase distribution channel 22-1 through the inlet A12-13, the oblique channel 23-1, the dispersed phase channel 12-13A, and the vertical channel 22-2 in sequence, and then the gas is dispersed into the dispersed phase threaded hole A12-11, the dispersed phase threaded hole B12-9, the dispersed phase threaded hole C12-7 and the dispersed phase threaded hole D12-3, and then passes through the first dispersed phase inlet channel 18-2, the second dispersed phase inlet channel 18-4, the third dispersed phase inlet channel 18-6 and the fourth dispersed phase inlet channel 1 8-8 enters four arc-shaped channels 18-10, and then enters four straight channels 18-9, so that bubbles are stably generated in the T-shaped channels of the bubble generation layer 18, and then the screwing depth of the M2 bolts in the continuous phase threaded hole A12-10, the continuous phase threaded hole B12-8, the continuous phase threaded hole C12-4, the continuous phase threaded hole D12-2, the dispersed phase threaded hole A12-11, the dispersed phase threaded hole B12-9, the dispersed phase threaded hole C12-7 and the dispersed phase threaded hole D12-3 is adjusted to change the degree of shielding of the channels by the above-mentioned bolts, so as to achieve the effect of fine-tuning the pressure in the channels, so that the size of the bubbles generated inside the T-shaped channels of the circular array is uniform; Step 6, after the polyvinyl alcohol composite hydrogel solution containing a large number of bubbles drips from the nozzle 14, the 3D microfluidic printing nozzle 9 is moved to 10 mm above the upper surface of the first refrigeration plate 10-1 using the control software, the high-voltage power switch is turned on, and the high-voltage power voltage is gradually increased to reduce the droplet size to the desired state; Step 7, write a nozzle movement control program of the required printing pattern through the control software, and control the 3D microfluidic printing nozzle 9 to cover the upper surface of the first refrigeration plate 10-1 and move repeatedly, so that the polyvinyl alcohol composite hydrogel solution containing bubbles drips onto the first refrigeration plate 10-1 and freezes quickly; Step 8, after the previous layer of polyvinyl alcohol composite hydrogel solution is completely frozen, the movement control program of the 3D microfluidic printing nozzle 9 is executed again to print a new layer of polyvinyl alcohol hydrogel on the previous layer of polyvinyl alcohol composite hydrogel; Step 9, repeating step 7 multiple times to form a frozen three-dimensional porous hydrogel structure; Step 10, placing the frozen three-dimensional porous hydrogel in a -20°C refrigerator, freezing for 12 hours, and then taking it out and placing it at room temperature for 1 hour; Step 11, repeating step 9 multiple times, gelling the three-dimensional porous hydrogel through freeze-thaw cycles to form a soft and elastic three-dimensional porous piezoelectric hydrogel.

[0027] The specific operation process of preparing the polyvinyl alcohol composite hydrogel solution in step 1 is as follows: polyvinyl alcohol, polyvinylidene fluoride, gelatin, sodium dodecyl sulfate and deionized water are added to a beaker in proportion, sealed with plastic wrap, placed in a magnetic stirring water bath, heated to 95°C, stirred with a magnetic stirrer for 2h, and the polyvinyl alcohol, polyvinylidene fluoride, gelatin and sodium dodecyl sulfate particles are completely dissolved, and then placed in a liquid storage bottle to obtain a polyvinyl alcohol composite hydrogel solution.

[0028] The ratio of the polyvinyl alcohol, polyvinylidene fluoride, gelatin, sodium dodecyl sulfate and deionized water is as follows: the polyvinyl alcohol composite hydrogel solution contains 8% by mass of polyvinyl alcohol, 4% by mass of gelatin, 7% by mass of polyvinylidene fluoride and 0.5% by mass of sodium dodecyl sulfate.

[0029] The gas is nitrogen or air.

[0030] By repeating step 8 for different times, porous piezoelectric gels of different thicknesses are prepared, which have different piezoelectric properties and can be adjusted by controlling the thickness. By adjusting the injection pump flow and the air pump pressure, porous piezoelectric gels of different porosities are prepared, which have different piezoelectric properties and can be adjusted by controlling the porosity.

[0031] The embodiments of the present invention disclose preferred embodiments, but are not limited thereto. A person skilled in the art can easily understand the spirit of the present invention based on the above embodiments and make different extensions and changes. However, as long as they do not deviate from the spirit of the present invention, they are all within the protection scope of the present invention.

Claims

1. A 3D microfluidic printing device, characterized in that: The invention comprises a base (1), wherein a support seat (2) and a support arm (5) are respectively mounted on the upper surface of the base (1), a bottom plate (3) for placing printed products is arranged on the upper surface of the support seat (2), a nozzle bracket (7) is movably arranged on the front side of the support arm (5), and a 3D microfluidic printing nozzle (9) is fixedly connected to the bottom end of the nozzle bracket (7).

2. A 3D microfluidic printing device according to claim 1, characterized in that: The 3D microfluidic printing nozzle (9) comprises a 3D microfluidic chip (12) and a chip connection plate (13) for fixedly connecting the 3D microfluidic chip (12) to a nozzle bracket (7); a boss is arranged on the front side of the 3D microfluidic chip (12); the 3D microfluidic chip (12) comprises an inlet A (12-13), an inlet B (12-12) and an outlet A (12-5); the bottom end of the outlet A (12-5) is coaxially and interference-fittedly connected to a nozzle (14); the 3D microfluidic chip ( 12) Six layers of microchannels are sequentially arranged along the radial direction of the dispersed phase threaded hole A (12-11) from the front side of the boss, and the six layers of microchannels are respectively a top layer (22), a dispersed phase inlet channel layer (23), a bubble generation layer (18), a continuous phase inlet channel layer (19), an outlet collection layer (20) and a bottom layer (21). The gas and material respectively introduced through the inlet A (12-13) and the inlet B (12-12) merge in the bubble generation layer (18) to generate a material containing a large number of bubbles for printing the porous piezoelectric gel.

3. A 3D microfluidic printing device according to claim 2, characterized in that: The upper surface of the support seat (2) is provided with a first slide groove (2-1), the first slide groove (2-1) is arranged along the Y axis, the inner bottom wall of the first slide groove (2-1) is slidably connected with a first slider (4), the bottom plate (3) is fixedly connected to the upper surface of the first slider (4) by means of a leveling bolt, an insulation shell (11) is horizontally installed at the exact center of the upper surface of the bottom plate (3), and a quick freezing device (10) is horizontally installed at the exact center of the interior of the insulation shell (11).

4. A 3D microfluidic printing device according to claim 3, characterized in that: The front of the support arm (5) is provided with a second slide groove (5-1), the second slide groove (5-1) is arranged along the X-axis, the inner bottom wall of the second slide groove (5-1) is slidably connected with a second slider (6-1), the front end of the second slider (6-1) is fixedly connected with a movable plate (6), the side of the movable plate (6) away from the second slider (6-1) is provided with a third slide groove (6-2), the third slide groove (6-2) is arranged along the Z-axis, the nozzle bracket (7) is slidably connected to the inner wall of the third slide groove (6-2), one end of the nozzle bracket (7) away from the third slide groove (6-2) is fixedly connected with a nozzle connecting plate (8) through four M4 bolts and hexagonal nuts, and the 3D microfluidic printing nozzle (9) is connected to the nozzle connecting plate (8) through four M2 bolts and nuts and then fixedly connected to the bottom end of the nozzle bracket (7).

5. A 3D microfluidic printing device according to claim 4, characterized in that: The diagonals of the 3D microfluidic chip (12) are respectively provided with a chip positioning hole A (12-1) and a chip positioning hole B (12-6); the front side of the boss is cross-shaped and is respectively provided with a dispersed phase threaded hole A (12-11), a dispersed phase threaded hole B (12-9), a dispersed phase threaded hole C (12-7) and a dispersed phase threaded hole D (12-3); the front side of the boss is X-shaped and is respectively provided with a continuous phase threaded hole A (12-10), a continuous phase threaded hole B (12-8), a continuous phase threaded hole C (12-9), and a dispersed phase threaded hole D (12-3); 4) and a continuous phase threaded hole D (12-2), the inlet A (12-13) and the inlet B (12-12) are arranged in a vertical direction on one side of the 3D microfluidic chip (12) close to the chip positioning hole A (12-1), the outlet A (12-5) is arranged in a vertical direction on one side of the 3D microfluidic chip (12) close to the chip positioning hole B (12-6), and the chip connecting plate (13) is fixedly connected to the chip positioning hole A (12-1) and the chip positioning hole B (12-6) by two M2 bolts.

6. A method for preparing a porous piezoelectric hydrogel based on the 3D microfluidic printing device according to any one of claims 1 to 5, characterized in that: The following steps are involved: Step 1, preparing a polyvinylidene fluoride-containing polyvinyl alcohol composite hydrogel solution, injecting the prepared polyvinylidene fluoride-containing polyvinyl alcohol composite hydrogel solution into a nitrogen pressure injection pump reservoir, connecting the syringe to the connecting tube A (17-1) through a Teflon hose, and then plugging it into the inlet A (12-2); Step 2, connect the nitrogen pressure injection pump to the connecting pipe B (17-2) through the Teflon hose, and then plug it into the inlet B (12-13); Step 3, turning on the low-temperature coolant circulation pump and the quick freezing device (10), and waiting for the metal surface temperatures of the first refrigeration plate (10-1), the second refrigeration plate (10-3) and the third refrigeration plate (10-5) to drop to below zero and stabilize; Step 4, screw four M2 bolts into the continuous phase threaded hole A (12-10), the continuous phase threaded hole B (12-8), the continuous phase threaded hole C (12-4) and the continuous phase threaded hole D (12-2) respectively, so that the continuous phase threaded hole A (12-10), the continuous phase threaded hole B (12-8), the continuous phase threaded hole C (12-4) and the continuous phase threaded hole D (12-2) remain in a closed state. Step 5, turning on the nitrogen pressure injection pump switch to stably generate bubbles in the T-shaped channel of the bubble generation layer (18); Step 6, after the polyvinyl alcohol composite hydrogel solution containing a large number of bubbles drips from the nozzle (14), the 3D microfluidic printing nozzle (9) is moved to 10 mm above the upper surface of the first refrigeration plate (10-1) using the control software, the high-voltage power switch is turned on, and the high-voltage power voltage is gradually increased to reduce the droplet size to a desired state; Step 7, a nozzle movement control program of the desired printing pattern is written through control software, and the 3D microfluidic printing nozzle (9) is controlled to cover the upper surface of the first refrigeration plate (10-1) with repeated movements, so that the polyvinyl alcohol composite hydrogel solution containing bubbles drips onto the first refrigeration plate (10-1) and freezes quickly; Step 8, after the previous layer of polyvinylidene fluoride-containing polyvinyl alcohol composite hydrogel solution is completely frozen, the movement control program of the 3D microfluidic printing nozzle (9) is executed again to print a new layer of polyvinyl alcohol hydrogel on the previous layer of polyvinylidene fluoride-containing polyvinyl alcohol composite hydrogel solution; Step 9, repeating step 7 multiple times to form a frozen three-dimensional porous hydrogel structure; Step 10, placing the frozen three-dimensional porous hydrogel in a -20°C refrigerator, freezing for 12 hours, and then taking it out and placing it at room temperature for 1 hour; Step 11, repeating step 9 multiple times, gelling the three-dimensional porous hydrogel through freeze-thaw cycles to form a soft and elastic three-dimensional porous piezoelectric hydrogel.

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