A 3D printer, artificial neuron and preparation method thereof

Abstract

The present invention belongs to the technical field related to the preparation of artificial neurons, and discloses a 3D printer, an artificial neuron, and a preparation method thereof. The artificial neuron includes a tactile receptor, a transmission unit, and an artificial synapse. The tactile receptor includes, from bottom to top, a first electrode layer, a sensing layer, and a second electrode layer, the sensing layer being disposed between the first and second electrode layers, wherein the sensing layer includes a conical sensing layer and a tubular sensing layer. The artificial synapse includes, from inside to outside, an electrolyte layer, a semiconductor layer, and an encapsulation layer, and is provided with a source electrode, a drain electrode, and a gate electrode. The source electrode and drain electrode are connected to the semiconductor layer, and the gate electrode is connected to the electrolyte layer. The first electrode layer or the second electrode layer is connected to the artificial synapse via a transmission unit. This application can produce an artificial neuron with multi-dimensional mechanical sensing, which has higher sensitivity and a wider range of applications.

Description

Technical Field

[0001] The present invention belongs to the technical field related to artificial neuron preparation, and more specifically, relates to a 3D printer, an artificial neuron and a preparation method thereof. Background Art

[0002] Biological tactile neurons have the functions of receiving stimuli, transmitting information, and perceiving and learning. Tactile sensation is generated by receptors on tactile neurons in the skin receiving signals and transmitting them along their axons to synapses. Postsynaptic neurons further integrate synchronous or asynchronous stimulation signals, resulting in multi-layered tactile perception. Artificial neurons, based on the mechanisms of biological tactile neurons, consist of tactile receptors, transmission units, and artificial synapses. Tactile receptors are devices that convert external stimuli into quantifiable electrical signals by utilizing changes in resistance, capacitance, or inductance in various electronic devices in response to external stimuli. Transmission units are devices that transmit quantified electrical signals to artificial synapses using electronic or ionic conductance. Artificial synapses convert digital signals, which are incomprehensible to biological organisms, into biological neural signals, forming the foundation for biomimetic perception systems and intelligent human-machine interfaces. They exhibit fundamental biological synaptic properties, such as short-term plasticity, long-term plasticity, and spike-timing-dependent plasticity. This type of artificial neuron, implemented in electronic hardware, is the foundation for building artificial neural networks and holds important implications for the development of human-machine interaction, robotic perception, and control systems.

[0003] The performance of current tactile receptors based on sensor principles has reached or even exceeded the limits of human perception. While their sensitivity can meet the requirements of existing artificial neuron applications, they suffer from a single structure, fixed mechanical properties, and an inability to conform to complex surfaces. Current artificial synapses are primarily implemented using two-terminal memristor devices or multi-terminal transistor devices. Three-terminal / multi-terminal synaptic transistors offer advantages such as good stability, relatively controllable test parameters, clear operating mechanisms, and the ability to be constructed from multiple materials. Furthermore, existing artificial neuron receptors, transmission units, and artificial synapses are all manufactured and assembled separately, which complicates assembly and results in poor integration.

[0004] Chinese patent CN112850635A discloses a method for preparing an artificial afferent nerve, a bionic sensory system, and an artificial afferent nerve, wherein the device preparation method is still a conventional manufacturing method for semiconductor devices, which is to mechanically combine a substrate, a sensor, a signal processing, and a signal storage device to realize the interconnection of neural sensory signals and biological signals. However, the disclosed preparation method still has the problem that it can only produce two-dimensional or three-dimensional structures with regular periodic arrangement, which is known to those skilled in the art. At the same time, it is limited by the demoulding and remolding processes, and many structures cannot be prepared. At the same time, when liquid electrolyte materials are involved, there are problems such as difficulty in packaging and serious interference from the external environment, which poses a great challenge to the sensitivity and manufacturing difficulty of neurons. Summary of the Invention

[0005] In response to the above-mentioned defects or improvement needs of the prior art, the present invention provides a 3D printer, an artificial neuron and a preparation method thereof, which can obtain an artificial neuron for multi-dimensional mechanical sensing with higher sensitivity and a wider range of applications.

[0006] To achieve the above objectives, according to one aspect of the present invention, an artificial neuron is provided, comprising a tactile receptor, a transmission unit, and an artificial synapse, wherein: the tactile receptor comprises, from bottom to top, a first electrode layer, a sensing layer, and a second electrode layer, the sensing layer being disposed between the first and second electrode layers, wherein the sensing layer comprises a conical sensing layer composed of a plurality of conical structures and a tubular sensing layer composed of a plurality of tubular structures, at least one end of each conical structure being provided with at least one layer of the tubular structure; the artificial synapse is a columnar structure, comprising, from inside to outside, an electrolyte layer, a semiconductor layer, and an encapsulation layer, wherein one end of each columnar structure is provided with a source electrode, the other end is provided with a drain electrode, and a gate electrode is provided in between, the source and drain electrodes being connected to the semiconductor layer, and the gate being connected to the electrolyte layer; the first electrode layer is connected to the gate via the transmission unit, and the second electrode layer is connected to the positive electrode of an external power supply, or the second electrode layer is connected to the gate via the transmission unit, and the first electrode layer is connected to the positive electrode of an external power supply; and the source electrode is connected to the negative electrode of the power supply.

[0007] Preferably, the conical structure includes a forward conical structure and an inverted conical structure, and the forward conical structure and the inverted conical structure are arranged in a staggered manner.

[0008] Preferably, the tubular structure and the conical structure are hollow structures in the axis.

[0009] Preferably, the sensing layer is a carbon nanotube-doped PDMS composite material; the material of the first electrode layer and the second electrode layer is one of conductive silver paste, conductive carbon paste, carbon nanotubes or silver nanotubes.

[0010] Preferably, the materials of the transmission unit and the electrolyte layer are ion conductive materials.

[0011] Preferably, the material of the semiconductor layer is an in-situ polymerized polyaniline material or poly (3,4-ethylenedioxythiophene):polystyrene sulfonate); and the material of the encapsulation layer is PDMS.

[0012] Preferably, a substrate is further provided at the bottom of the tactile receptor, and the material of the substrate is PDMS.

[0013] According to another aspect of the present invention, a 3D printer for printing the above-mentioned artificial neurons is provided. The 3D printer includes a conventional nozzle and a coaxial nozzle. The coaxial nozzle is composed of two coaxially arranged nozzle tubes, each of which corresponds to a material barrel. The internal nozzle can also be connected to a preset pressure gas.

[0014] According to another aspect of the present invention, a method for manufacturing the artificial neuron using the above-mentioned 3D printer is provided, the method comprising: preparing a tactile receptor: using the conventional nozzle to print the substrate layer and the first conductive layer, using the coaxial nozzle to print the sensing layer, and using the conventional nozzle to print the second conductive layer; preparing an artificial synapse: using the coaxial nozzle to prepare the tubular packaging layer, the drain electrode, and the source electrode; preparing a semiconductor layer using a polymer coating method; injecting an electrolyte material into the hollow tube inside the semiconductor; and preparing a transmission unit: using the coaxial nozzle to prepare the transmission unit.

[0015] Preferably, when preparing the sensing layer, when preparing a tubular sensing layer, gas at a preset pressure is introduced into the internal nozzle tube during the preparation process, thereby printing out a hollow tubular structure; when preparing a conical structure, gas at a preset pressure is introduced into the internal nozzle tube during the preparation process, and the slurry pressure of the external nozzle tube is increased or decreased in sequence, thereby printing out a hollow conical structure.

[0016] In general, the above technical solutions conceived by the present invention have the following beneficial effects compared with the prior art:

[0017] 1. The sensing layer of the present application includes a conical sensing layer and a tubular sensing layer. The tubular sensing layer senses external pressure signals. Through the gradual compression and deformation of the hollow tubular structures at each level and the contact inside the tube, multi-stage sensing can be constructed. By adjusting the thickness of the tube and the proportion of the internal components of the material, its resistance sensitivity can be adjusted. The conical sensing layer can not only sense external pressure signals, but also sense external shear stress signals. Under the action of external shear stress, the conical structures change from separation to contact, and further squeeze each other, causing a change in resistance, and then sense the external shear stress signal.

[0018] 2. The conical sensing layer includes a positive conical structure and an inverted conical structure. The two structural shapes are arranged alternately, which can make the sensing of cutting signals more stable.

[0019] 3. 3D printing allows for the convenient and efficient preparation of tactile receptors of different sizes, arrangements, and combinations. When preparing artificial synapses, the semiconductor layer and electrolyte layer can be quickly and easily encapsulated inside the hollow tube, greatly improving the environmental tolerance of the artificial synapse and avoiding the influence of the external environment on the electrolyte materials of traditional organic electrochemical transistors.

[0020] 4. The artificial neurons prepared by the method provided by the present invention imitate the architecture and working mechanism of biological neurons, couple neuronal functions such as tactile perception, signal transmission and tactile perception learning, and have tactile perception and learning functions. Artificial neurons are basic devices for building neural networks. At the same time, the method of 3D printing neurons provided in this application breaks through the limitations of traditional flexible electronic device preparation processes on product structure complexity, device integration and long manufacturing cycle. Through 3D printing technology, flexible adjustment of the size, structure and arrangement of each device can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic structural diagram of an artificial neuron according to an embodiment of the present application;

[0022] Figure 2 is another structural schematic diagram of the artificial neuron according to an embodiment of the present application;

[0023] Figure 3 is a schematic structural diagram of an artificial synapse according to an embodiment of the present application;

[0024] Figure 4A This is a schematic structural diagram of the sensing layer before deformation in an embodiment of the present application;

[0025] Figure 4B This is a schematic diagram of the structure of the sensing layer after deformation in an embodiment of the present application;

[0026] Figure 5 Schematic diagram of a 3D printer printing an artificial neuron according to an embodiment of the present application;

[0027] Figure 6A Schematic diagram of the structure of the coaxial nozzle of the 3D printer according to the embodiment of the present application;

[0028] Figure 6B is a cross-sectional view of a coaxial nozzle of a 3D printer according to an embodiment of the present application;

[0029] Figure 7 It is a parameter curve diagram of the printed conical structure of the 3D printer in the embodiment of the present application.

[0030] Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0031] 101 - X / Y / Z three-axis motion platform; 102 - forming substrate; 103 - general nozzle; 200, 210 - coaxial nozzle; 300 - printing sample; 121, 123 - first barrel; 122 - second barrel; 124 - third barrel; 125 - fourth barrel; 126 - fifth barrel; 127 - barrel bracket; 131 - solenoid valve; 132 - first high-pressure air pipe; 133 - second high-pressure air pipe; 134 - third high-pressure air pipe Tube; 201-outer nozzle base; 202-inner nozzle; 203-outer nozzle; 310-substrate; 320-tactile receptor; 330-artificial synapse; 340-transmission unit; 321-first electrode layer; 322-tubular sensing layer; 323-conical sensing layer; 324-second electrode layer; 331-electrolyte layer; 332-semiconductor layer; 333-encapsulation layer; 334-source; 335-drain; 336-gate. DETAILED DESCRIPTION

[0032] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0033] See also Figure 1 and Figure 2 In a first aspect, the present invention provides an artificial neuron, which includes a tactile receptor 320, a transmission unit 340 and an artificial synapse 330, and the specific structure is as follows.

[0034] The tactile receptor 320 includes, from bottom to top, a first electrode layer 321, a sensing layer, and a second electrode layer 324. The sensing layer is arranged between the first electrode layer 321 and the second electrode layer 324. The sensing layer includes a conical sensing layer 323 composed of multiple conical structures and a tubular sensing layer 322 composed of multiple tubular structures. At least one end of the conical structure is provided with at least one layer of the tubular structure.

[0035] Further preferably, the conical structure includes a positive conical structure and an inverted conical structure, and the positive conical structure and the inverted conical structure are arranged in a staggered manner.

[0036] Further preferably, the tubular structure is an axially hollow structure, and the conical structure is an axially hollow structure.

[0037] A substrate 310 is further provided at the bottom of the tactile receptor 320 , and the material of the substrate 310 is PDMS.

[0038] The sensing layer is a PDMS composite material doped with carbon nanotubes; more preferably, it is a PDMS composite material doped with carbon nanotubes, polyaniline or polypyrrole.

[0039] The material of the first electrode layer 321 and the second electrode layer 324 is a conductive silver paste, a conductive carbon paste, a carbon nanotube or a silver nanotube.

[0040] The tubular sensing layer of the tactile receptor 320 is arranged parallel to or at an angle between the first electrode layer 321 and the second electrode layer 324. The number of tubular sensing layers, tube spacing, tube wall thickness, and diameter can be controlled by adjusting 3D printing parameters. Under external pressure loads, the tubular sensing layer of the tactile receptor undergoes two-stage deformation, achieving resistive sensing of external compressive stress.

[0041] The conical sensing layers of the tactile receptors 320 are arranged in opposite directions between the tubular sensing layers. The orientation, taper, spacing, and height of the conical sensing layers can be controlled by varying 3D printing parameters. Under external shear stress, the adjacent conical structures of the tactile receptors change from separation to contact, achieving resistive sensing of external shear stress.

[0042] like Figure 3 As shown, the artificial synapse 330 is a columnar structure, which includes, from the inside to the outside, an electrolyte layer 331, a semiconductor layer 332, and an encapsulation layer 333. The columnar structure has a source electrode 334 at one end and a drain electrode 335 at the other end, with a gate electrode 336 in the middle. The source electrode 334 and the drain electrode 335 are connected to the semiconductor layer 332, and the gate electrode 336 is connected to the electrolyte layer 331.

[0043] The first electrode layer 321 is connected to the gate through the transmission unit, and the second electrode layer 324 is connected to the positive pole of the external power supply, or the second electrode layer is connected to the gate through the transmission unit, and the first electrode layer 321 is connected to the positive pole of the external power supply; the source is connected to the negative pole of the power supply.

[0044] like Figure 4A and 4BAs shown, under external compressive stress, tubular sensing layer 322 is compressed, and adjacent tube walls come into contact, resulting in a decrease in resistance. Under external shear stress, adjacent conical sensing layers 323 come into contact, further reducing resistance. The sensing unit transmits the electrical signal changes from the tactile receptors to the gate 336 of the artificial synapse, which is based on the principles of an organic electrochemical transistor. The polymer electrolyte regulates the doping level of the artificial synapse's semiconductor layer 332, thereby changing the resistance between the drain 335 and source 334 of the artificial synapse, ultimately achieving tactile perception and learning.

[0045] Further preferably, the materials of the transmission unit 340 and the electrolyte layer are ion-conductive materials, such as polyvinyl alcohol or polyethylene oxide doped with calcium chloride, lithium chloride, etc. The material of the semiconductor layer is in-situ polymerized polyaniline (PANI) material or poly (3,4-ethylenedioxythiophene:polystyrene sulfonate) (PEDOT:PSS); and the material of the encapsulation layer is PDMS.

[0046] The artificial synapse controls the voltage loaded between the gate and source electrodes immersed in the electrolyte layer, the migration of ions in the electrolyte, and the reversible change of the conductivity of the semiconductor layer, thereby realizing short-term synaptic plasticity and long-term synaptic plasticity in the synapse.

[0047] The second aspect of the present application provides a 3D printer, which in this embodiment is a multi-material ink direct writing 3D printer, such as Figure 5 As shown, it includes an X / Y / Z three-axis motion platform 101, a heatable formable substrate 102, a common nozzle 103, and coaxial nozzles 200 and 210 for printing transmission units and tactile sensing layers. A first barrel 121 and 123 filled with PDMS material, a second barrel 122 filled with carbon nanotube-doped PDMS composite material, a third barrel 124 filled with polymer electrolyte, a fourth barrel 125 not filled with printing paste, a fifth barrel 126 filled with conductive silver paste, and a barrel holder 127. A solenoid valve 131 for controlling the switching of the material extrusion gas path, a first high-pressure air pipe 132 for controlling the extrusion of PDMS or PDMS / CNT material, a second high-pressure air pipe 133 for controlling the extrusion of polymer electrolyte, a third high-pressure air pipe 134 for controlling the extrusion of conductive silver paste material, and a printed sample 300. The schematic diagram of the coaxial nozzle structure is shown in FIG. Figure 6A and 6B As shown, it mainly includes an outer nozzle base 201, an inner nozzle 202 and an outer nozzle 203.

[0048] A third aspect of the present application provides a method for printing the artificial neuron using the above-mentioned printer, and the method includes the following steps S1 to S3.

[0049] S1: Preparation of tactile receptors:

[0050] The common nozzle is used to print the substrate layer and the first conductive layer, the coaxial nozzle is used to print the sensing layer, and the common nozzle is used to print the second conductive layer.

[0051] a) Printing substrate layer

[0052] The movement of the print head is controlled according to the preset printing trajectory of the multi-material ink direct writing 3D printer. The substrate material is pneumatically extruded. After each layer of printing is completed, the substrate layer is accumulated layer by layer according to the thickness of the printed layer. After printing is completed, the printed substrate is heated, and after the substrate is solidified, the substrate is cooled to obtain the substrate layer.

[0053] b) Printing the first conductive layer

[0054] According to the requirements of the sensing layer connection circuit, the multi-material ink direct writing 3D printer print head is controlled to move, and the conductive paste is pneumatically extruded. After printing is completed, the printed substrate is placed. After the conductive layer is solidified, the substrate is cooled to obtain the conductive layer.

[0055] c) Preparation of sensing layer materials

[0056] Carbon nanotubes (CNTs) were added to a 0.1 wt% aqueous solution of cetyltrimethylammonium bromide at a ratio of 0.1-1.0 mg / mL and sonicated for 30-120 minutes. The dispersed CNT slurry and PDMS were added to dichloromethane at a ratio of 5-10 wt%. After thorough stirring and dispersion, the solvent was evaporated at 80°C for 8 hours to prepare the slurry for printing the sensing layer.

[0057] d) Preparation of tubular sensing layer

[0058] The tubular sensing layer is printed using a multi-material ink direct-write 3D printer equipped with a dual-layer coaxial nozzle. The inner side of the coaxial nozzle is connected to atmospheric pressure, while the outer side is connected to a barrel filled with printing slurry. After forming one to five tubular sensing layers, depending on the carbon nanotube ratio and resistive sensitivity requirements, the substrate is heated to 120-180°C for 30-60 minutes to cure.

[0059] e) Preparation of conical sensing layer

[0060] A multi-material ink direct-write 3D printer equipped with a double-layer coaxial nozzle is used to print the conical sensing layer. After the nozzle is moved to the forming position, the printer's Z-axis is controlled to rise while the extrusion air pressure is gradually reduced from 600-800kPa to 100-400kPa. As the extrusion air pressure gradually decreases, the amount of slurry extruded at the nozzle outlet decreases, forming a sensing layer with a positive conical structure. After the nozzle is moved to the next printing position, the printer's Z-axis is controlled to rise while the extrusion air pressure is gradually increased from 100-400kPa to 600-800kPa, forming a sensing layer with an inverted conical structure. After forming the sensing layer with alternating positive and inverted cones according to the motion trajectory, the formed substrate is heated to 120-180°C and held at this temperature for 30-60 minutes to solidify.

[0061] S2: Preparation of artificial synapses:

[0062] a) using the coaxial nozzle to prepare the tubular encapsulation layer, drain electrode and source electrode;

[0063] A multi-material ink direct-write 3D printer equipped with a dual-layer coaxial nozzle is used to print the tubular encapsulation layer, drain, and source electrodes. The inner side of the coaxial nozzle is connected to a barrel filled with conductive silver paste, while the outer side is connected to a barrel filled with encapsulation material. After the nozzle is moved to the forming position based on the artificial neuron layout and the functional requirements of the artificial synapse, the inner and outer extrusion pressures of the coaxial nozzle are controlled to extrude the conductive silver paste electrodes simultaneously, forming the encapsulated conductive silver paste electrodes. The inner extrusion pressure is then stopped to print the outermost encapsulation layer of the artificial synapse. Finally, the inner extrusion pressure is restarted to print the other electrode of the artificial synapse.

[0064] b) preparing the semiconductor layer by a polymer coating method;

[0065] The variable resistance polymer coating is prepared inside the tubular packaging layer by in-situ polymerization or other polymer coating preparation methods. A polymer monomer or polymer solution is injected into the tubular packaging layer, and the coating is formed inside the tubular packaging layer after in-situ polymerization or heating to remove the solvent.

[0066] c) injecting an electrolyte material into the hollow tube inside the semiconductor;

[0067] An ion-conductive material is prepared by thoroughly mixing an aqueous solution of LiCl or CaCl2 with a polyethylene oxide or polyvinyl alcohol hydrogel. This is then injected into the hollow tube after the semiconductor layer is deposited to create the electrolyte layer of the artificial synapse.

[0068] S3: Transfer cell preparation:

[0069] The transmission unit is prepared by using the coaxial nozzle.

[0070] A multi-material ink direct-write 3D printer equipped with a dual-layer coaxial nozzle printhead was used to print the transfer unit. The inner side of the coaxial nozzle was connected to a cartridge containing the polymer electrolyte material prepared in Step 2, while the outer side of the coaxial nozzle was connected to a cartridge containing PDMS. Simultaneously, the extrusion pressure connected to the inner and outer connecting cartridges of the coaxial nozzle extruded the printing slurry, connecting the conductive layer of the tactile receptors to the artificial synaptic electrodes. After the components were connected, the substrate was heated to 180°C for curing.

[0071] Furthermore, the multi-material ink direct writing 3D printer prints by pneumatic extrusion to push the slurry printing, the extrusion pressure range is 100-800kPa, the printing layer thickness is 100-600μm, the printing speed range is 100-800mm / min, and the printing track spacing is 100-1500μm.

[0072] Furthermore, the diameter of the printing nozzles for the substrate layer and the electrode layer ranges from 100 to 600 μm.

[0073] Furthermore, the tubular sensing layer, the conical sensing layer, the artificial synapse and the connection unit are printed using coaxial dual nozzles, with the inner diameter of the coaxial nozzle ranging from 100 to 300 μm and the outer diameter of the coaxial nozzle ranging from 500 to 800 μm.

[0074] Furthermore, during the preparation of the conical sensing layer, the extrusion air pressure changes linearly or in steps during the Z-axis lifting process.

[0075] Example 1

[0076] This embodiment provides a method for preparing an artificial neuron with tactile perception and learning function using the above-mentioned 3D printer, comprising the following steps:

[0077] (1) PDMS SYLGARD 184A component and PDMS SYLGARD 184B component were mixed in a ratio of 10:1 and stirred thoroughly to prepare a slurry for printing the substrate and encapsulation layer.

[0078] (2) The substrate printing slurry prepared in step (1) is loaded into the barrel. After the conventional nozzle 103 with a nozzle diameter of 200 μm is moved to the forming position, the solenoid valve 131 is switched to extrude the PDMS in the first barrel 123 through the first high-pressure air pipe 132 at an extrusion pressure of 400 kPa, printing two substrate layers with a thickness of 100 μm. After the substrate layer is printed, the formed substrate is heated to 120°C and cooled after the substrate is solidified.

[0079] (3) CNTs were added to a 0.1 wt% aqueous solution of cetyltrimethylammonium bromide at a ratio of 1.0 mg / mL and sonicated for 120 min. The dispersed CNT slurry and PDMS were added to dichloromethane at a ratio of 10 wt%. After thorough stirring and dispersion, the solvent was evaporated at 80°C to a constant weight to prepare a slurry for printing the sensing layer.

[0080] (4) After the coaxial nozzle 200 with an inner diameter of 200 μm and an outer diameter of 500 μm is moved to the forming position, the inner side of the coaxial nozzle is connected to the atmospheric pressure, and the outer side of the coaxial nozzle is connected to the barrel containing the printing slurry of the sensing layer. The switching solenoid valve 131 is used to extrude the PDMS / CNT composite material slurry in the second barrel 122 through the first high-pressure air pipe 132 when the extrusion pressure is 600 kPa, and print the tubular sensing layer on the substrate prepared in step (2). According to the resistance sensitivity requirement, the printing track spacing is set to 700 μm. After forming two layers of tubular sensing layers, the forming substrate is heated to 180°C to solidify the tubular sensing layer.

[0081] (5) After the coaxial nozzle 200 is moved to the forming position, a conical sensing layer is printed on the tubular sensing layer prepared in step (4). The printer Z axis is controlled to rise and the extrusion pressure is controlled to decrease from 700 kPa to 300 kPa in a stepwise manner. As the extrusion pressure gradually decreases, the amount of slurry extruded at the nozzle outlet decreases, forming a sensing layer with a positive conical structure. The control method is as follows: Figure 7 As shown in the figure, the nozzle is then moved to the printing position. The printer's Z-axis is raised while the extrusion pressure is gradually increased from 300kPa to 700kPa, forming an inverted-conical sensing layer. After the sensing layer, alternating positive and inverted cones, is formed according to the motion trajectory, the substrate is heated to 180°C for curing.

[0082] (6) A common nozzle 103 with a nozzle diameter of 200 μm is moved above the tactile receptor prepared in step (5), and the PDMS in the fifth barrel 126 is extruded through the third high-pressure air pipe 134 at an extrusion pressure of 200 kPa to print a layer of conductive silver paste with a thickness of 200 μm. The formed substrate is heated to 150° C., and the substrate is cooled after the electrode layer is solidified to complete the printing of the tactile receptor.

[0083] (7) A 0.1 M LiCl aqueous solution was thoroughly mixed with 5 mg / mL polyethylene oxide hydrogel to prepare a polymer electrolyte material.

[0084] (8) After the coaxial nozzle 210 is moved to the forming position, the artificial synapse is printed around the tactile receptor prepared in step (6). The inner side of the coaxial nozzle is connected to the first barrel 121 filled with PDMS slurry, and the outer side of the coaxial nozzle is connected to the third barrel 124 filled with polymer electrolyte. The first high-pressure air pipe 132 is used to extrude the air pressure of 400kPa, and the second high-pressure air pipe 133 is used to extrude the air pressure inside and outside the coaxial nozzle at the same time under the condition of 200kPa, so as to print the PDMS-encapsulated polymer electrolyte electrode. Then, the air pressure supply of the second high-pressure air pipe 133 is stopped, and the extrusion air pressure of the first high-pressure air pipe 132 is maintained unchanged, so as to print the outermost encapsulation layer of the artificial synapse. Finally, the air pressure supply of the third high-pressure air pipe 134 is started again to print the other electrode of the artificial synapse. The forming substrate is heated to 180°C for curing.

[0085] (9) Dissolve ammonium persulfate in deionized water, then dissolve aniline and phytic acid in deionized water and mix thoroughly by ultrasonication for 30 minutes. Slowly add the ammonium persulfate solution dropwise to the mixture under ice bath conditions, wherein the molar ratio of aniline:ammonium persulfate:phytic acid is 1:2:1.5. Inject the mixed solution into the tubular packaging layer printed in step (8). After reacting for 3 hours, carefully clean the PDMS hollow tube with the polyaniline coating.

[0086] (10) The polymer electrolyte prepared in step (7) is injected into the hollow PDMS tube with polyaniline coating prepared in step (9) to prepare the electrolyte layer of the artificial synapse.

[0087] (11) After the artificial synapse is prepared, the tactile receptor electrode layer prepared in step (6) and the artificial synapse electrode prepared in step (9) are connected using a coaxial nozzle 210 with the same parameters as the electrodes printed in step (8). After the connection of the components is completed, the formed substrate is heated to 180°C for curing.

[0088] Example 2

[0089] (1) PDMS SE 1700A component and B component were mixed in a ratio of 10:1 and stirred thoroughly to prepare a slurry for printing the substrate and encapsulation layer.

[0090] (2) The substrate printing slurry prepared in step (1) is loaded into the barrel. After the conventional nozzle 103 with a nozzle diameter of 400 μm is moved to the forming position, the solenoid valve 131 is switched to extrude the PDMS in the first barrel 123 through the first high-pressure air pipe 132 at an extrusion pressure of 500 kPa, printing one substrate layer with a thickness of 300 μm. After the substrate layer is printed, the formed substrate is heated to 120°C and cooled after the substrate is solidified.

[0091] (3) CNTs were added to a 0.1 wt% aqueous solution of cetyltrimethylammonium bromide at a ratio of 0.5 mg / mL and sonicated for 120 min. The dispersed CNT slurry and PDMS were added to dichloromethane at a ratio of 5 wt%. After thorough stirring and dispersion, the solvent was evaporated at 80°C to a constant weight to prepare a slurry for printing the sensing layer.

[0092] (4) After the coaxial nozzle 200 with an inner diameter of 300 μm and an outer diameter of 700 μm is moved to the forming position, the inner side of the coaxial nozzle is connected to the atmospheric pressure, and the outer side of the coaxial nozzle is connected to the barrel containing the printing slurry of the sensing layer. The switching solenoid valve 131 extrude the PDMS / CNT composite material slurry in the second barrel 122 through the first high-pressure air pipe 132 at an extrusion pressure of 800 kPa, and print the tubular sensing layer on the substrate prepared in step (2). According to the resistance sensitivity requirement, the printing track spacing is set to 900 μm. After forming three layers of tubular sensing layers, the forming substrate is heated to 180°C to solidify the tubular sensing layer, completing the printing of the tubular sensing layer.

[0093] (5) After the coaxial nozzle 200 is moved to the forming position, a conical sensing layer is printed on the tubular sensing layer prepared in step (4). The printer Z-axis is controlled to rise and the extrusion pressure is controlled to gradually decrease from 800kPa to 400kPa. As the extrusion pressure gradually decreases, the amount of slurry extruded at the nozzle outlet decreases, forming a sensing layer with a positive conical structure. Subsequently, after the nozzle is moved to the position to be printed, the printer Z-axis is controlled to rise and the extrusion pressure is controlled to gradually increase from 400kPa to 800kPa, forming a sensing layer with an inverted conical structure. After forming the sensing layer with alternating positive and inverted cones according to the motion trajectory, the formed substrate is heated to 180°C for solidification.

[0094] (6) A common nozzle 103 with a nozzle diameter of 400 μm is moved above the tactile receptor prepared in step (5), and the PDMS in the fifth barrel 126 is extruded through the third high-pressure air pipe 134 at an extrusion pressure of 200 kPa to print two layers of conductive silver paste with a thickness of 200 μm. The formed substrate is heated to 150° C., and the substrate is cooled after the electrode layer is solidified to complete the printing of the tactile receptor.

[0095] (7) A 0.5 M CaCl2 aqueous solution was fully mixed with polyvinyl alcohol hydrogel to prepare a polymer electrolyte material.

[0096] (8) After the coaxial nozzle 210 is moved to the forming position, the artificial synapse is printed around the tactile receptor prepared in step (6). The inner side of the coaxial nozzle is connected to the first barrel 121 filled with PDMS slurry, and the outer side of the coaxial nozzle is connected to the third barrel 124 filled with conductive silver paste. The first high-pressure air pipe 132 is used to extrude the air pressure of 500kPa, and the second high-pressure air pipe 133 is used to extrude the air pressure inside and outside the coaxial nozzle at the same time under the condition of the extrusion pressure of 200kPa, thereby printing the polymer electrolyte electrode encapsulated by PDMS. Subsequently, the air pressure supply of the second high-pressure air pipe 133 is stopped, and the extrusion pressure of the first high-pressure air pipe 132 is maintained unchanged, thereby printing the outermost encapsulation layer of the artificial synapse. Finally, the air pressure supply of the second high-pressure air pipe 133 is started again to print the other electrode of the artificial synapse. The forming substrate is heated to 180°C for curing.

[0097] (9) PEDOT:PSS was blended with ethylene glycol (conductivity enhancer), 3-glycidyl ether propyl trimethoxysilane (crosslinker), and dodecylbenzene sulfonic acid (dispersant) in a volume ratio of 100:5:1:0.25. The mixed solution was injected into the tubular encapsulation layer printed in step (7). The substrate was heated to 100°C. After the solvent evaporated, a PEDOT:PSS film was formed in the PDMS hollow tube.

[0098] (9) A 0.5 M CaCl2 aqueous solution and a polyvinyl alcohol hydrogel were fully mixed to prepare a polymer electrolyte material, which was then injected into the hollow PDMS tube with a PEDOT:PSS coating prepared in step (8) to prepare the electrolyte layer of the artificial synapse.

[0099] (10) The polymer electrolyte prepared in step (7) is injected into the hollow PDMS tube with polyaniline coating prepared in step (9) to prepare the electrolyte layer of the artificial synapse.

[0100] (11) After the artificial synapse is prepared, the tactile receptor electrode layer prepared in step (6) and the artificial synapse electrode prepared in step (9) are connected using a coaxial nozzle 210 with the same parameters as the electrodes printed in step (8). After the connection of the components is completed, the formed substrate is heated to 180°C for curing.

[0101] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An artificial neuron, characterized in that The artificial neuron includes a tactile receptor, a transmission unit, and an artificial synapse, wherein: The tactile receptor comprises, from bottom to top, a first electrode layer, a sensing layer, and a second electrode layer. The sensing layer is arranged between the first electrode layer and the second electrode layer. The sensing layer comprises a conical sensing layer composed of a plurality of conical structures and a tubular sensing layer composed of a plurality of tubular structures. At least one end of the conical structure is provided with at least one layer of the tubular structure. The artificial synapse is a columnar structure, which includes an electrolyte layer, a semiconductor layer, and an encapsulation layer from the inside out. A source electrode is provided at one end of the columnar structure, a drain electrode is provided at the other end, and a gate electrode is provided in the middle. The source electrode and the drain electrode are connected to the semiconductor layer, and the gate electrode is connected to the electrolyte layer. The first electrode layer is connected to the gate through the transmission unit, and the second electrode layer is connected to the positive electrode of the external power supply, or the second electrode layer is connected to the gate through the transmission unit, and the first electrode layer is connected to the positive electrode of the external power supply; the source is connected to the negative electrode of the power supply; The tubular structure and the conical structure are hollow structures in the axis; The conical structure includes a forward conical structure and an inverted conical structure, and the forward conical structure and the inverted conical structure are arranged in a staggered manner.

2. The artificial neuron according to claim 1, characterized in that The sensing layer is a carbon nanotube-doped PDMS composite material; the material of the first electrode layer and the second electrode layer is one of conductive silver paste and conductive carbon paste.

3. The artificial neuron according to claim 1, wherein The materials of the transmission unit and the electrolyte layer are ion conductive materials.

4. The artificial neuron according to claim 1, wherein The material of the semiconductor layer is an in-situ polymerized polyaniline material or poly (3,4-ethylenedioxythiophene):polystyrene sulfonate); the material of the encapsulation layer is PDMS.

5. The artificial neuron according to claim 1, wherein A substrate is further provided at the bottom of the tactile receptor, and the material of the substrate is PDMS.

6. A method for printing the artificial neuron according to any one of claims 1 to 5 using a 3D printer, characterized in that: The 3D printer includes a common nozzle and a coaxial nozzle. The coaxial nozzle is composed of two coaxially arranged nozzle tubes, each of which corresponds to a barrel. The inner nozzle is also connected to a gas at a preset pressure. The method includes: Preparation of tactile receptors: The substrate layer and the first conductive layer are printed using the common nozzle, the sensing layer is printed using the coaxial nozzle, and the second conductive layer is printed using the common nozzle; Preparation of artificial synapses: Using the coaxial nozzle to prepare the tubular packaging layer, drain electrode and source electrode; The semiconductor layer is prepared by a polymer coating method; injecting an electrolyte material into the hollow tube inside the semiconductor; Transfer cell preparation: The transmission unit is prepared by using the coaxial nozzle.

7. The method according to claim 6, characterized in that When preparing the sensing layer, when preparing a tubular sensing layer, gas of preset pressure is introduced into the internal nozzle tube during the preparation process, thereby printing out a hollow tubular structure; when preparing a conical structure, gas of preset pressure is introduced into the internal nozzle tube during the preparation process, and the slurry pressure of the external nozzle tube is increased or decreased in sequence, thereby printing out a hollow conical structure.

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