Ionogel photodetector and neuromorphic vision sensor and method of making the same

Abstract

The application discloses a preparation method of an ion gel light detection and neuromorphic visual sensor and an application field thereof. The ion gel light detection and neuromorphic visual sensor comprises a transparent substrate, a pure ion gel layer, a light-heat nanometer material doped ion gel layer and an electrode. The pure ion gel layer is an acrylate gel material containing only ion conductive materials, and the light-heat ion gel layer is obtained by doping light-heat nanoparticles in the pure ion gel. Under light conditions, the light-heat nanoparticles in the light-heat ion gel layer absorb light, a temperature difference is generated between the light-heat ion gel layer and the pure ion gel under the light-heat effect, and then an internal potential difference and an ion current are formed. The intensity of the ion current changes with the wavelength and intensity of light, and obvious light response characteristics are exhibited. In addition, the ion gel light detection and neuromorphic visual sensor also has the advantages of simple preparation process, wide-band response, self-power supply, flexibility and the like.

Description

Technical Field

[0001] This invention relates to the field of ionoelectric photoelectric synaptic device technology, specifically to an ion gel photodetector and neuromorphic vision sensor, its preparation method, and its application fields. Background Technology

[0002] With the development of the electronic information industry, optoelectronic sensors have important applications in fields such as light detection, information storage, and computing. The limitations of traditional silicon-based optoelectronic devices in terms of physical size and application scenarios are becoming increasingly prominent. Flexible optoelectronic devices, due to their advantages of flexibility, light weight, portability, and low power consumption, greatly expand the application range of electronic devices, overcoming the inherent limitations of silicon-based devices and providing important ideas for the development of devices in the post-Moore's Law era. Furthermore, the application scenarios for optoelectronic devices are gradually expanding from planar to curved surfaces, leading to a continuous increase in demand for curved optoelectronic devices. Since traditional CMOS processes are not suitable for manufacturing curved micro- and nano-sized devices, there is an urgent need to develop new materials and new technologies.

[0003] Inspired by biological vision systems, developing curved optoelectronic bionic eyes is considered an important direction for solving problems such as vignetting and distortion in existing planar optoelectronic sensors, and is applicable to fields such as bionic robotics and medical vision restoration. Visual generation includes visual imaging and neuronal transmission processes, but most current bionic eyes are limited to light detection functions. Developing devices with both light sensing and synaptic functions can greatly improve information perception and processing capabilities. However, the materials currently used for curved light detection or photosynaptic devices are mainly silicon-based semiconductor materials, inorganic two-dimensional materials, or perovskite materials. Although they can achieve excellent performance, these materials are generally complex to fabricate, and their inherent rigid structure limits the practical application of these devices in the field of flexible electronics.

[0004] Ion gels have attracted widespread attention in medical, sensing, and energy storage fields due to their excellent mechanical properties, solution processing capabilities, good conductivity, and electroresponsiveness. Under external influences, such as electrical or thermal stimulation, ions in ion gel copolymers can move locally between polymer chains and ion coordination sites, generating the migration of cations and anions and forming ionic currents. Currently, there are many sensors based on ion gels, but optoelectronic devices based on ion gels are still rarely reported. The development of ion gel photodetectors and neuromorphic vision sensors provides an opportunity to realize flexible curved surface optoelectronic sensors. Summary of the Invention

[0005] This invention discloses an integrated neuromorphic visual sensing array biomimetic eye synapse device, providing a dual-ended artificial photoelectric synapse array based on the photothermal and electroelectric properties of ion gel and its fabrication method. This invention forms a dual-ended device of gel / photothermal gel by doping polypyrrole photothermal nanoparticles (photothermal gel) into an existing ion gel, while maintaining a consistent ion count within both gels. Upon illumination, a temperature difference arises due to the different degrees of light absorption and heating on both sides. Under this temperature difference, the directional migration of ions caused by the Solette effect and the formation of a stable current loop by the external circuitry are achieved. Utilizing the properties of the photothermal gel, self-powered flexible curved surfaces and a wide-band optical response can be realized.

[0006] The technical solution of this invention is as follows: an ion gel photodetector and neuromorphic vision sensor, the sensor comprising a plurality of synaptic device array units, the synaptic device array unit structure comprising a spherical transparent substrate, a pure ion gel layer, a photothermal nanomaterial-doped ion gel layer, and a metal electrode. The bottom electrode is a common electrode, located on the ion gel side of each individual synaptic unit; each top electrode independently covers one side of the doped photothermal gel.

[0007] The spherical transparent substrate is made of quartz glass and has a thickness of approximately 500 micrometers.

[0008] The gel precursor solution is composed of acrylic monomer, crosslinking agent, ionic salt and photoinitiator.

[0009] The acrylic monomer is butyl acrylate, the conductivity-enhancing ethoxyethyl acrylate is selected, the crosslinking agent is ethoxylated trimethylolpropane triacrylate, the ionic salt is lithium bis(trifluoromethanesulfonyl)imide, and the photoinitiator is 1-hydroxycyclohexylphenyl ketone.

[0010] The bottom electrode and top electrode are Ag.

[0011] The fabrication method of the aforementioned integrated neuromorphic visual sensing array and bionic ocular synapse device includes:

[0012] (1) A transparent ionogel layer is prepared on a transparent quartz substrate to form a uniform film;

[0013] (2) The conductive silver paste is uniformly coated onto one side of the ion gel film by screen printing technology.

[0014] (3) A photothermal ion gel layer is prepared on the ion gel film, and a patterned photothermal gel array is obtained through a customized mask;

[0015] (4) A conductive silver paste is coated on the photothermal gel array to obtain an integrated neuromorphic visual sensing array and a bionic eye synapse device.

[0016] The technical solution of the present invention has the following advantages:

[0017] 1. The device array of this invention can be adapted to fabrication on various complex flexible / rigid surfaces, possessing excellent commonality capabilities, and providing a new approach for the fabrication of flexible curved surface photoelectric sensors. In terms of material selection, the chosen ionogel is more biomimetic, and the diversity of ions provides possibilities for multifunctional photoelectric sensor applications.

[0018] 2. In terms of performance, this device possesses the ability to simulate neuromorphic synapses, and is expected to find applications in future neuromorphic optoelectronic chips and intelligent vision systems. Due to its photothermoelectric process, it achieves self-powered operation without external power input. Furthermore, it has a wide optical response band and an on / off ratio of approximately 10. 2 It has high stability.

[0019] 3. The integrated neuromorphic visual sensing array and bionic eye synapse device contain multiple synaptic units. Its fabrication process is simple, effectively solving the problems of complex processes and unfavorable large-scale production and application in the existing technology, and providing the possibility for realizing large-scale integrated devices. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure and photoresponse characteristics of the planar ion gel photodetector and neuromorphic vision sensor of the present invention.

[0021] Figure 2 This is a schematic diagram of the structure and photoresponse characteristics of the vertical ion gel photodetector and neuromorphic vision sensor of the present invention.

[0022] Figure 3 This invention provides optical pulses at different wavelengths (intensity of μW / mm²). 2 The relationship between postsynaptic current and time under stimulation.

[0023] Figure 4 This is a graph showing the relationship between postsynaptic current and time under a series of light pulses of different intensities (wavelength in nm, duration in s).

[0024] Figure 5 This is a graph showing the relationship between temperature difference and doping concentration for photothermal nanoparticles of the present invention with different doping concentrations.

[0025] Figure 6 This invention provides the real-time visualization results of the letter "I" using an ion gel photodetector and neuromorphic vision sensor.

[0026] The components are: 1. Lens; 2. Quartz substrate; 3. Transparent ionogel layer; 4. Photothermal ionogel layer; 5. Bottom electrode; 6. Top electrode. Detailed Implementation

[0027] Example 1

[0028] A planar ion-gel photodetector and neuromorphic vision sensor includes several synaptic device units. Each synaptic unit includes a substrate, and electrodes are disposed between the substrate and the ion-gel heterojunction, located at both ends of the heterojunction and connected by conductive silver paste.

[0029] The fabrication method of the above-mentioned ion gel photodetector and neuromorphic vision sensor includes the following steps in sequence:

[0030] (1) Transparent substrate treatment: The planar quartz sheet was ultrasonically treated with deionized water, ethanol and isopropanol for 15 min respectively, and then dried with nitrogen gas for later use.

[0031] (2) Preparation of gel precursor solution: 1 mL butyl acrylate, 3 mL ethoxy ethoxy ethyl acrylate, 12.5 μL ethoxylated trimethylolpropane triacrylate, 0.17 g 1-hydroxycyclohexylphenyl ketone, and 0.7 g lithium bis(trifluoromethanesulfonylimide) were stirred in the dark for 2 h to make them evenly mixed and ready for use.

[0032] (3) Preparation of photothermal gel precursor solution: Polypyrrole nanoparticles were synthesized by one-step dispersion polymerization, and particles with a size <100nm were separated. The nanoparticles were mixed with the precursor solution obtained in (2) and stirred in the dark for 2 hours. The concentration was set to 0.75mg / mL.

[0033] (4) Preparation of transparent ion gel: Take 1 mL of precursor solution and add it into a square mold with a partition. Irradiate with a UV lamp with a power of 10 W for 1 min to obtain a planar ion gel film of half the size of the mold.

[0034] (5) Preparation of photothermal ionogel layer: Add an equal amount of photothermal gel precursor liquid to the other side of the transparent ionogel in (4) for secondary photopolymerization, and irradiate with a UV lamp power of 10W for 2 minutes. Remove the gel to obtain the ionogel heterojunction.

[0035] (6) Electrode preparation: The planar ion gel is laid flat on the release film, and an appropriate amount of conductive silver paste is screen printed to obtain planar electrodes on both sides.

[0036] Example 2

[0037] An ion gel photodetector and neuromorphic vision sensor includes several synaptic device units. Each synaptic unit includes a substrate 2. A bottom electrode 5 is disposed between the substrate 2 and a transparent ion gel layer 3. A photothermal ion gel layer 4 containing photothermal nanoparticles is disposed on the ion gel 3. The photothermal ion gel layer 4 is connected to a top electrode 6 and a wire using conductive silver paste.

[0038] The fabrication method of the above-mentioned ion gel photodetector and neuromorphic vision sensor includes the following steps in sequence:

[0039] (1) Transparent substrate treatment: The spherical quartz substrate was ultrasonically treated with deionized water, ethanol and isopropanol for 15 min respectively, and then dried with nitrogen for later use.

[0040] (2) Preparation of gel precursor solution: 1 mL butyl acrylate, 3 mL ethoxy ethoxy ethyl acrylate, 12.5 μL ethoxylated trimethylolpropane triacrylate, 0.17 g 1-hydroxycyclohexylphenyl ketone, and 0.7 g lithium bis(trifluoromethanesulfonylimide) were stirred in the dark for 2 h to make them evenly mixed and ready for use.

[0041] (3) Preparation of photothermal gel precursor solution: Polypyrrole nanoparticles were synthesized by one-step dispersion polymerization, and particles with a size <100nm were separated. The nanoparticles were mixed with the precursor solution obtained in (2) and stirred in the dark for 2 hours. The concentration was set to 0.75mg / mL.

[0042] (4) Preparation of transparent ion gel layer: 400 μL of precursor solution was added to the gap between the spherical substrate and the concave mold. The UV lamp was irradiated with a power of 10 W for 1 min to obtain a curved ion gel film that adheres to the surface of the spherical substrate.

[0043] (5) Preparation of patterned photothermal ionogel layer: After peeling the transparent ionogel from (4) off the spherical substrate, stretch and flatten it on the release film. Place the customized mask on the ionogel, drop 200 μL of photothermal gel precursor into the holes of the mask, and irradiate with a UV lamp of 10 W for 2 min. Remove the mask to obtain the photothermal gel array.

[0044] (6) Preparation of bottom electrode: The side with the photothermal gel array is laid flat on the release film, and an appropriate amount of conductive silver paste is used to screen print the bottom electrode.

[0045] (7) Top electrode preparation: After uniformly dipping the gel array obtained in step (5) into conductive silver paste, quickly attach it to the wire to obtain the ion gel photodetector and neuromorphic vision sensor.

[0046] Example 3

[0047] (1) Transparent substrate treatment: The spherical quartz substrate was ultrasonically treated with deionized water, ethanol and isopropanol for 15 min respectively, and then dried with nitrogen for later use.

[0048] (2) Preparation of gel precursor solution: 1 mL butyl acrylate, 3 mL ethoxy ethoxy ethyl acrylate, 12.5 μL ethoxylated trimethylolpropane triacrylate, 0.17 g 1-hydroxycyclohexylphenyl ketone, and 0.7 g lithium bis(trifluoromethanesulfonylimide) were stirred in the dark for 2 h to make them evenly mixed and ready for use.

[0049] (3) Preparation of photothermal gel precursor solution: Polypyrrole nanoparticles were synthesized by one-step dispersion polymerization, and particles with a size <100nm were separated. The nanoparticles were mixed with the precursor solution obtained in (2) and stirred in the dark for 2 hours. The concentration was set to 0.5mg / mL.

[0050] (4) Preparation of transparent ion gel layer: 400 μL of precursor solution was added to the gap between the spherical substrate and the concave mold. The UV lamp was irradiated with a power of 10 W for 1 min to obtain a curved ion gel film that adheres to the surface of the spherical substrate.

[0051] (5) Preparation of patterned photothermal ionogel layer: After peeling the transparent ionogel from (4) off the spherical substrate, stretch and flatten it on the release film. Place the customized mask on the ionogel, drop 200 μL of photothermal gel precursor into the holes of the mask, and irradiate with a UV lamp power of 10 W for 1 min. Remove the mask to obtain the photothermal gel array.

[0052] (6) Preparation of bottom electrode: The side with the photothermal gel array is laid flat on the release film, and the Al electrode is prepared by vapor deposition.

[0053] (7) Top electrode preparation: Au electrode is prepared by vapor deposition of the gel array obtained in step (5), thus obtaining the ion gel photodetector and neuromorphic vision sensor.

[0054] Example 4

[0055] (1) Transparent substrate treatment: The spherical quartz substrate was ultrasonically treated with deionized water, ethanol and isopropanol for 15 min respectively, and then dried with nitrogen for later use.

[0056] (2) Preparation of gel precursor solution: 1 mL butyl acrylate, 3 mL ethoxy ethoxy ethyl acrylate, 12.5 μL ethoxylated trimethylolpropane triacrylate, 0.17 g 1-hydroxycyclohexylphenyl ketone, and 0.7 g lithium bis(trifluoromethanesulfonylimide) were stirred in the dark for 2 h to make them evenly mixed and ready for use.

[0057] (3) Preparation of photothermal gel precursor solution: Polypyrrole nanoparticles were synthesized by one-step dispersion polymerization, and particles with a size <100nm were separated. The nanoparticles were mixed with the precursor solution obtained in (2) and stirred in the dark for 2 hours. The concentration was set to 1mg / mL.

[0058] (4) Preparation of transparent ion gel layer: 400 μL of precursor solution was added to the gap between the spherical substrate and the concave mold. The UV lamp was irradiated with a power of 10 W for 1 min to obtain a curved ion gel film that adheres to the surface of the spherical substrate.

[0059] (5) Preparation of patterned photothermal ionogel layer: After peeling the transparent ionogel from (4) off the spherical substrate, stretch and flatten it on the release film. Place the customized mask on the ionogel, drop 200 μL of photothermal gel precursor into the holes of the mask, and irradiate with a UV lamp power of 10 W for 3 min. Remove the mask to obtain the photothermal gel array.

[0060] (6) Preparation of bottom electrode: The side with the photothermal gel array is laid flat on the release film, and an appropriate amount of conductive graphene is drop-coated to obtain the bottom electrode.

[0061] (7) Top electrode preparation: The gel array obtained in step (5) is uniformly dipped into carbon nanotubes to obtain the ion gel photodetector and neuromorphic vision sensor.

[0062] The present invention also tested the performance of the ion gel photodetector and neuromorphic vision sensor prepared in the above embodiments. Taking the photoresponsive neural synapse bionic electronic device prepared in Example 1 as an example, the performance was tested using a semiconductor parameter analyzer (Keithley 4200SCS) at an intensity of μW / mm². 2 The device prepared above was tested under 0V conditions under light irradiation, and the results are as follows. Figure 1-2 As shown, illumination causes the device current to gradually increase from the initial state, and after the illumination is removed, the device current value gradually decreases and tends to stabilize. Its decrease time is much longer than that of biological neurons, thus exhibiting "memory plasticity" similar to that of biological neurons.

[0063] Depend on Figure 3-4 It is known that in the current-time test, the process of applying light pulse stimulation is similar to the repeated writing of information, i.e., the "learning" process. The excitatory postsynaptic current of the device under light pulse stimulation of different wavelengths and intensities shows an increasing trend, successfully realizing the writing of optical information. This plastic biological characteristic makes the application of neuromorphic optoelectronic chips and intelligent vision systems possible.

[0064] Performance tests on the devices prepared in Examples 3 and 4 revealed that their performance trends were consistent with those in Examples 1 and 2. Characterization of doping concentration showed little performance improvement after reaching a doping concentration of 0.75 mg / mL.

[0065] The real-time acquired data is transmitted through an amplifier, a data acquisition card, and LabVIEW. Figure 6 The real-time working effect of the ion gel photodetector and neuromorphic vision sensor under the illumination of the letter "I" was demonstrated. This ion-electro-electronic device, due to its excellent mechanical and electrical properties and versatility, will be suitable for artificial retinas, curved photoelectric detection and many other application scenarios.

[0066] The embodiments described above provide a detailed explanation of the technical solutions of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, additions, or similar substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An ion-gel photodetector and neuromorphic visual sensor, characterized in that: The sensor comprises several artificial photoelectric synaptic device array units. Each artificial photoelectric synaptic device array unit includes a spherical transparent substrate, a pure ion gel layer, a photothermal nanomaterial-doped ion gel layer, and a metal electrode. The array unit is a double-ended device based on the photothermal and electroelectric properties of ion gel, consisting of a pure ion gel and a photothermal nanomaterial-doped ion gel heterojunction. The number of ions within the two gels remains consistent. Upon illumination, the different degrees of light absorption and temperature rise on both sides of the pure ion gel and photothermal nanomaterial-doped ion gel generate a temperature difference, allowing ion migration and the external circuitry to form a stable current loop. The pure ion gel layer is an acrylate-based gel material. The photothermal nanomaterial-doped ion gel layer is formed by doping a photothermal nanomaterial into the pure ion gel layer.

2. The ion gel photodetector and neuromorphic vision sensor according to claim 1, characterized in that: The transparent substrate is one of a glass substrate, a polymer substrate, or a quartz substrate.

3. The ion gel photodetector and neuromorphic visual sensor according to claim 1, characterized in that: The sensor can be a planar structure or a vertical structure.

4. The ion gel photodetector and neuromorphic visual sensor according to claim 3, characterized in that: The sensor is a planar pure ion gel layer and a photothermal nanomaterial-doped ion gel layer that is planar; the sensor is a vertical pure ion gel layer and a photothermal nanomaterial-doped ion gel layer that is a multi-layer stacked vertical ion gel heterojunction.

5. The ion gel photodetector and neuromorphic vision sensor according to claim 1, characterized in that: The photothermal nanomaterials used to prepare the photothermal ion gel layer include one or more of polypyrrole, polydopamine, nano-iron oxide, MXene, nano-copper sulfide, and carbon black.

6. The method for fabricating the ion gel photodetector and neuromorphic visual sensor according to claim 1, characterized in that: A method for fabricating a planar ion-gel photodetector and neuromorphic vision sensor includes the following fabrication steps: Preparation of planar ion gel heterostructure: A pure ion gel layer was prepared by photopolymerization in a mold with a partition. After the reaction was completed, the partition was removed, and a photothermal nanomaterial-doped ion gel layer was prepared on one side of the pure ion gel layer. Electrode fabrication: Electrodes were fabricated on pure ion gel layers and photothermal nanomaterial-doped ion gel layers by means of transfer, spraying, screen printing or thermal evaporation.

7. The method for fabricating the ion gel photodetector and neuromorphic visual sensor according to claim 1, characterized in that: A method for fabricating a vertically structured ion gel photodetector and neuromorphic vision sensor, characterized by the following fabrication steps: Preparation of vertical ion gel heterostructure: After preparing a pure ion gel layer in a mold, it is transferred to a planar substrate, and then a patterned photothermal ion gel array is prepared on the surface of the transparent ion gel layer. Electrode fabrication: Electrodes were fabricated on pure ion gel layers and photothermal nanomaterial-doped ion gel layers by means of transfer, spraying, screen printing or thermal evaporation.

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