Neuromorphic gas sensor based on ionic gel and memristor and preparation method thereof
By integrating an ion-gel capacitive gas sensing unit and a Mott memristor on a substrate, a room-temperature neuromorphic gas sensor was constructed, solving the problem of poor compatibility between traditional gas sensors and brain-like computing systems. This achieved a miniaturized and low-power gas sensing front-end, supporting efficient brain-like intelligent perception.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HANGZHOU INST FOR ADVANCED STUDY UCAS
- Filing Date
- 2025-12-17
- Publication Date
- 2026-06-12
AI Technical Summary
Existing gas sensors have poor compatibility with neuromorphic computing systems, are large in size, consume a lot of power, and are difficult to integrate. Traditional gas sensors require high temperatures to operate and are difficult to achieve stable pulse signal output.
An ion gel capacitive gas sensing unit and a Mott memristor are heterogeneously integrated on a substrate, and an oscillation circuit is constructed using micro-nano fabrication technology. The charging and discharging cycle of the Mott memristor is modulated by the double-layer capacitance of the ion gel interface in response to changes in gas adsorption, thereby realizing in-situ frequency encoding of gas concentration information.
A neuromorphic gas sensor with room temperature operation, small size, and low power consumption has been developed, which can be directly and seamlessly connected to spiking neural networks to support efficient brain-like intelligent sensing systems.
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Figure CN121364221B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of microelectronic devices and intelligent sensing technology, specifically to a neuromorphic gas sensor based on ion gel and memristor and its preparation method. Background Technology
[0002] Artificial intelligence technology is evolving towards a bio-inspired brain-like computing architecture. Brain-like perception systems, centered on spiking neural networks (SNNs), have shown great potential in the field of intelligent sensing due to their high energy efficiency and event-driven characteristics. However, one of the current bottlenecks in the development of brain-like systems lies in the information acquisition end. Traditional gas sensors generally adopt a "sensing-analog-to-digital conversion-processing" mode based on the von Neumann architecture. The continuous analog signals output are not directly compatible with SNNs that process pulse signals, usually requiring additional complex circuitry for signal conversion, which introduces problems such as delay, power consumption, and increased system size.
[0003] To address the above problems, existing technologies have primarily explored two approaches:
[0004] The first approach involves connecting discrete gas sensors (such as semiconductor metal oxide gas sensors) and discrete memristors via external resistors, capacitors, and other components to convert analog signals into pulse signals. However, this method fails to achieve physical integration of the devices, resulting in a large system size. Furthermore, metal oxide sensors require a high-temperature operating environment of 300-500°C, leading to high power consumption and introducing difficult-to-solve thermal crosstalk and thermal stress problems, severely hindering the miniaturization and integration of the devices.
[0005] The second approach involves exploring the gas-sensitive properties of the memristor resistive switching layer material (such as certain metal oxides) to attempt to achieve dual functionality in a single device. However, this method often struggles to balance excellent memristor characteristics with high-sensitivity gas-sensitive properties, and it also faces the challenge of operating at high temperatures, making it difficult to achieve stable pulse signal output.
[0006] Therefore, there is an urgent need for a new gas sensor architecture that can operate at room temperature, be integrated on-chip, and integrate gas sensing and pulse coding functions. Summary of the Invention
[0007] To address the aforementioned issues, this invention provides a monolithically integrated, compact, room-temperature operating neuromorphic gas sensor and its fabrication method that enables integrated "sensing-encoding." This addresses the problems of poor compatibility, large size, high power consumption, and difficulty in integration of traditional gas sensors with neuromorphic computing systems, providing an efficient gas sensing front-end for neuromorphic intelligent sensing systems.
[0008] The embodiments of the present invention adopt the following technical solutions:
[0009] In a first aspect, the present invention provides a neuromorphic gas sensor based on ion gel and memristor, comprising: an ion gel capacitive gas sensing unit and a Mott memristor.
[0010] The ion gel capacitive gas sensing unit and the Mott memristor are heterogeneously integrated on the substrate using micro-nano fabrication technology and are electrically connected by metal interconnects to form an oscillation circuit.
[0011] The double-layer capacitance of the ion gel interface in the ion gel capacitive gas sensing unit changes in response to gas adsorption, modulating the charge and discharge cycle of the Mott memristor, so that the frequency of the output pulse signal is correlated with the gas concentration, thereby converting the gas concentration information into the frequency of the output pulse signal.
[0012] Preferably, the substrate material is Si, Si / SiO2, quartz, or Al2O3.
[0013] Preferably, the Mott memristor includes electrodes and a resistive switching layer, with the electrodes electrically connected to a metal interconnect.
[0014] Preferably, the resistive switching layer is an electronically strongly correlated material with the characteristic of inducing metal-insulator phase transition by electric field or thermal excitation, and the thickness of the resistive switching layer is 100~500 nanometers.
[0015] Preferably, the electron strongly correlated material is VO2 or NbO2.
[0016] Preferably, the ion gel capacitive gas sensing unit includes interdigitated electrodes and a gas-sensitive layer, with the interdigitated electrodes electrically connected to a metal interconnect.
[0017] Preferably, the gas-sensitive layer is an ion gel film with a thickness of 500~2000 nanometers.
[0018] Preferably, the ionogel film includes an ionic liquid; the ionic liquid is an imidazole-based, pyridine-based, quaternary ammonium-based, quaternary phosphorus-based, pyrrolidine-based, or piperidine-based ionic liquid.
[0019] Secondly, the present invention also provides a method for preparing a neuromorphic gas sensor based on ion gel and memristor, comprising the following steps:
[0020] An interdigitated electrode, a metal interconnect, and a Mott memristor are fabricated on a substrate for an ion gel capacitive gas sensing unit. The interdigitated electrode and the electrode of the Mott memristor are electrically connected to the metal interconnect to form an oscillating circuit.
[0021] A passivation layer is deposited on the area outside the interdigitated electrode region and the pad region of the metal interconnect of the ion gel capacitive gas sensing unit.
[0022] A gas-sensitive layer is prepared in the interdigitated electrode region.
[0023] Preferably, the interdigitated electrodes, metal interconnects, and Mott memristors of the ion-gel capacitive gas sensing unit are fabricated on the substrate, including:
[0024] A first mask is prepared by spin-coating photoresist and combining it with photolithography; the first mask covers the area other than the interdigitated electrodes, metal interconnects and the two end electrodes of the Mott memristor.
[0025] An adhesion layer material and an electrode metal material are deposited sequentially by electron beam evaporation. A stripping process is then used to remove the first mask and the adhesion layer material and electrode metal material covering the first mask, forming interdigitated electrodes, metal interconnects, and two-end electrodes.
[0026] VO2 was deposited in the electrode regions at both ends by magnetron sputtering, and then annealed to form a crystallized resistive switching layer.
[0027] Preferably, the interdigitated electrodes, metal interconnects, and Mott memristors of the ion-gel capacitive gas sensing unit are fabricated on the substrate, including:
[0028] A second mask is prepared by spin-coating photoresist and combining it with photolithography; the second mask masks the area outside the bottom electrode of the Mott memristor.
[0029] An adhesion layer material and an electrode metal material are deposited sequentially by electron beam evaporation. A stripping process is then used to remove the second mask and the adhesion layer material and electrode metal material covering the second mask to form the bottom electrode.
[0030] NbO2 was deposited in the bottom electrode region by magnetron sputtering and then annealed to form a crystallized resistive switching layer.
[0031] A third mask is prepared by spin-coating photoresist and combining it with photolithography; the third mask masks the area outside the top electrode of the Mott memristor.
[0032] An adhesion layer material and an electrode metal material are deposited sequentially by electron beam evaporation. A stripping process is then used to remove the third mask and the adhesion layer material and electrode metal material covering the third mask to form the top electrode.
[0033] A fourth mask is prepared by spin-coating photoresist and combining it with photolithography; the fourth mask masks the area outside the interdigitated electrodes and metal interconnects.
[0034] An adhesion layer material and an electrode metal material are deposited sequentially by electron beam evaporation. A stripping process is then used to remove the fourth mask and the adhesion layer material and electrode metal material covering the fourth mask, forming interdigitated electrodes and metal interconnects.
[0035] Preferably, a passivation layer is deposited on the area outside the interdigitated electrode region and the pad region of the metal interconnect of the ion-gel capacitive gas sensing unit, including:
[0036] Deposition of passivation materials;
[0037] Photolithography and reactive ion etching processes are used to selectively remove passivation material from the interdigitated electrode region and the pad region to form a passivation layer.
[0038] Preferably, a gas-sensitive layer is fabricated in the interdigitated electrode region, comprising:
[0039] Spin-coating a mixed solution of ionic liquid, polymer monomer, crosslinking agent, and photoinitiator to form a liquid film;
[0040] Cover the liquid film with an insulating film;
[0041] Ultraviolet exposure is performed using a mask that covers the area outside the interdigitated electrode region, causing the mixed solution in the interdigitated electrode region to undergo a photo-initiated polymerization reaction;
[0042] After exposure, the barrier film is removed and the mixed solution in the unexposed areas is removed to form a patterned solid ion gel film as a gas-sensitive layer.
[0043] Thirdly, the present invention also provides an application of a neuromorphic gas sensor based on ion gel and memristor for detecting toxic and harmful gases, including ammonia and nitrogen dioxide.
[0044] This invention provides a neuromorphic gas sensor based on ionogel and memristor. The ionogel capacitive gas sensing unit utilizes the sensitivity of the ionogel interfacial double-layer capacitance to gas adsorption as a modulation capacitor in the oscillation circuit. When gas molecules are adsorbed by the ionogel, the charge distribution and thickness of the interfacial double layer change, causing a change in capacitance. This capacitance change directly modulates the charge-discharge cycle of the Mott memristor in the oscillation circuit: an increase in capacitance results in a longer charge-discharge cycle and a lower pulse frequency; a decrease in capacitance results in a shorter charge-discharge cycle and a higher pulse frequency. Therefore, the frequency of the output pulse signal of the Mott memristor establishes a mapping relationship with the external gas concentration, realizing in-situ frequency encoding of gas concentration information.
[0045] This invention deeply integrates a gas-sensing unit (ion-gel capacitive gas sensing unit) with a pulse-coding unit (Mott memristor), completing the entire process from gas concentration signal sensing to pulse frequency encoding within a single integrated device, eliminating the need for traditional complex analog-to-digital conversion circuits. This "integrated sensing and computing" architecture allows it to serve as a native front-end, seamlessly interfacing with neuromorphic computing systems such as spiking neural networks, and has broad application prospects in fields such as the Internet of Things, robotic environmental perception, and portable medical diagnostics.
[0046] By heterogeneously integrating an ion-gel capacitive gas sensing unit with a Mott memristor on a single substrate, a compact, single-device structure is constructed. This integration method significantly reduces size, avoids parasitic effects and reliability issues caused by discrete component connections, and lays the foundation for building high-density neuromorphic sensing arrays.
[0047] The ion gel photolithography patterning process, the magnetron sputtering and annealing process for the Mott memristor resistive switching layer, and the metal electrode fabrication process used in this invention are all compatible with mainstream semiconductor CMOS manufacturing processes. This ensures that the sensor has the potential for mass production at low cost, which is conducive to promoting its industrialization and practical application. Attached Figure Description
[0048] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:
[0049] Figure 1 A schematic diagram of the structure of a neuromorphic gas sensor based on ion gel and memristor according to Embodiment 1 of the present invention is shown;
[0050] Figure 2 A circuit diagram of a neuromorphic gas sensor based on ion gel and memristor according to Embodiment 1 of the present invention is shown.
[0051] Figure 3 The diagram shows the gas-sensitive response curve of the neuromorphic gas sensor based on ion gel and memristor according to Embodiment 1 of the present invention, where (a) represents the introduction of clean and dry air, (b) represents the introduction of 20 ppm ammonia, (c) represents the introduction of 40 ppm ammonia, and (d) represents the introduction of 60 ppm ammonia. Detailed Implementation
[0052] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.
[0053] The following is a detailed description of the neuromorphic gas sensor based on ion gel and memristor proposed in this invention through specific embodiments.
[0054] Example 1:
[0055] 1. An interdigitated electrode, a metal interconnect, and a Mott memristor are fabricated on a substrate for an ion-gel capacitive gas sensing unit. The interdigitated electrode and the electrode of the Mott memristor are electrically connected to the metal interconnect to form an oscillation circuit.
[0056] (1) A double-sided polished high-resistivity Si wafer with 300 nm thermally grown SiO2 on the surface was selected as the substrate. The substrate was ultrasonically cleaned in acetone, ethanol and deionized water for 15 minutes each, and then dried with nitrogen gas for later use.
[0057] (2) Positive photoresist (AZ5214) was spin-coated onto the substrate at 3000 rpm for 50 seconds to form a photoresist layer with a thickness of approximately 1.5 micrometers. Ultraviolet exposure was performed using a mask defining the interdigitated electrodes, metal interconnects, and end electrodes (this mask masked the area outside the interdigitated electrodes, metal interconnects, and end electrodes) at an exposure energy of 120 mJ / cm². 2 After exposure, develop with AZ400K developer (diluted with deionized water at a ratio of 1:4) for 40 seconds to remove the photoresist from the exposed areas.
[0058] (3) Titanium of 10 nm and gold of 100 nm are deposited sequentially using an electron beam evaporation device. The photoresist and the titanium and gold covering the photoresist are removed by immersion in acetone for 30 minutes to form interdigitated electrodes, metal interconnects and two-end electrodes.
[0059] (4) Using a magnetron sputtering system, high-purity VO2 (99.9% purity) was used as the target material. Under the conditions of an argon to oxygen flow ratio of 49:1, working pressure of 0.5 Pa, and sputtering power of 100 W, VO2 with a thickness of 100 nm was deposited in the electrode area at both ends at room temperature.
[0060] (5) Place it in a rapid annealing furnace, and in a nitrogen environment (flow rate 2 liters / minute), rapidly heat it to 400°C at a rate of 20°C / second and hold it for 60 seconds. Then, allow it to cool naturally so that VO2 crystallizes to form a resistive switching layer with metal-insulator phase transition characteristics.
[0061] 2. Deposit a passivation layer on the area outside the interdigitated electrode region and the pad region of the metal interconnect of the ion gel capacitive gas sensing unit.
[0062] (1) SiO2 with a thickness of 100 nanometers was deposited using plasma-enhanced chemical vapor deposition.
[0063] (2) Photolithography and reactive ion etching processes are used to selectively remove SiO2 from the interdigitated electrode area and the pad area to form a passivation layer.
[0064] 3. Prepare a gas-sensitive layer in the interdigitated electrode region.
[0065] (1) Mix the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ([EMIM][Tf2N]), the polymer monomer hydroxyethyl acrylate (HEA), and the crosslinking agent polyethylene glycol diacrylate (PEGDA, Mn=250) in a mass ratio of 80:18:2. Then add the photoinitiator Irgacure819, which accounts for 1 wt% of the total mass of the polymer monomers. Stir magnetically for 2 hours under light-protected conditions until the mixture is completely homogeneous.
[0066] (2) Spin-coating the precursor mixture solution with parameters set to 2000 rpm and 30 seconds to form a uniform liquid film with a thickness of about 2 micrometers.
[0067] (3) Cover the liquid film with a high-transmittance polyethylene terephthalate (PET) film to isolate oxygen.
[0068] (4) Use a mask to expose the area outside the interdigitated electrode area to perform ultraviolet exposure. The exposure parameters are wavelength 365 nm, intensity 10 mW / cm², and time 30 seconds, so that the mixed solution in the interdigitated electrode area undergoes photo-initiated polymerization reaction.
[0069] (5) After exposure, remove the PET film and immerse it in anhydrous ethanol for 10 seconds to remove the unpolymerized mixed solution in the unexposed area. Finally, a patterned solid ion gel film is formed in the interdigitated electrode area as a gas-sensitive layer.
[0070] Figure 1 A schematic diagram of the neuromorphic gas sensor based on ion gel and memristor of Example 1 is shown. Figure 1 In the diagram, 1 represents a Mott memristor, 2 represents an ion gel capacitive gas sensing unit, 3 represents a substrate, 4 represents a passivation layer, and 5 represents a metal interconnect.
[0071] When using the gas sensor prepared in Example 1 for gas detection, the workflow is as follows: The gas sensor is installed in a gas-sensitive test chamber, and a load resistor is connected in series with an external device via a probe station for protection. A constant DC bias voltage of 1 volt (V) is applied to the oscillation circuit of the gas sensor using a semiconductor parameter analyzer (such as a Keysight B1500A). in Simultaneously, an oscilloscope (such as a Tektronix MDO3024) was used to monitor and record the voltage pulse signal (V) of the metal interconnect in real time. out ). Figure 2 The circuit diagram of the neuromorphic gas sensor based on ion gel and memristor of Example 1 is shown.
[0072] At the start of the test, clean, dry air is first introduced into the test chamber, and the reference pulse frequency output by the gas sensor is measured and recorded. Then, a target gas (such as ammonia) of a specific concentration (e.g., 20-60 ppm) is introduced into the test chamber. During this process, the bias voltage is kept constant, and the change in the output pulse frequency is monitored in real time. After the test is completed, the target gas is cut off, and clean air is introduced for purging until the pulse frequency output by the gas sensor returns to the reference value. Figure 3 The diagram shows the gas-sensitive response curve of the neuromorphic gas sensor based on ion gel and memristor in Example 1, i.e., the voltage pulse signal measured under different concentrations of target gas.
[0073] Example 2:
[0074] 1. An interdigitated electrode, a metal interconnect, and a Mott memristor are fabricated on a substrate for an ion-gel capacitive gas sensing unit. The interdigitated electrode and the electrode of the Mott memristor are electrically connected to the metal interconnect to form an oscillation circuit.
[0075] (1) A double-sided polished high-resistivity Si wafer with 300 nm thermally grown SiO2 on the surface was selected as the substrate. The substrate was ultrasonically cleaned in acetone, ethanol and deionized water for 15 minutes each, and then dried with nitrogen gas for later use.
[0076] (2) A positive photoresist (AZ5214) was spin-coated onto the substrate at 3000 rpm for 50 seconds to form a photoresist layer with a thickness of approximately 1.5 micrometers. Ultraviolet exposure was performed using a mask defining the bottom electrode (which masked the area outside the bottom electrode) at an exposure energy of 120 mJ / cm². 2 After exposure, develop with AZ400K developer (diluted with deionized water at a ratio of 1:4) for 40 seconds to remove the photoresist from the exposed areas.
[0077] (3) Titanium of 10 nm and gold of 100 nm are deposited sequentially using an electron beam evaporation device. The photoresist and the titanium and gold covering the photoresist are removed by immersion in acetone for 30 minutes to form the bottom electrode.
[0078] (4) Using a magnetron sputtering system with high-purity niobium (99.95% purity) as the target material, NbO2 with a thickness of 80 nm was deposited in the bottom electrode region at 300 °C under the conditions of an argon to oxygen flow ratio of 2:1, a working pressure of 0.6 Pa, and a sputtering power of 120 W. By precisely controlling the oxygen partial pressure, an NbO2 phase with a stoichiometric ratio close to 1:2 was obtained.
[0079] (5) Place it in a rapid annealing furnace, and in a nitrogen environment (flow rate 2 liters / minute), rapidly heat it to 600°C at a rate of 20°C / second and hold it for 60 seconds. Then, allow it to cool naturally so that NbO2 crystallizes to form a resistive switching layer with metal-insulator phase transition characteristics.
[0080] (6) Spin-coating positive photoresist (AZ5214) with parameters set to 3000 rpm for 50 seconds to form a photoresist layer with a thickness of approximately 1.5 micrometers. UV exposure was performed using a mask with a defined top electrode (which masked the area outside the top electrode) at an exposure energy of 120 mJ / cm². 2 After exposure, develop with AZ400K developer (diluted with deionized water at a ratio of 1:4) for 40 seconds to remove the photoresist from the exposed areas.
[0081] (7) 10 nm titanium and 100 nm gold were deposited sequentially using an electron beam evaporation device, and then the photoresist and the titanium and gold covering the photoresist were removed by immersion in acetone for 30 minutes to form the top electrode.
[0082] (8) Spin-coating positive photoresist (AZ5214) with parameters set to 3000 rpm for 50 seconds to form a photoresist layer with a thickness of approximately 1.5 micrometers. UV exposure was performed using a mask defining the interdigitated electrodes and metal interconnects (the mask concealed the areas outside the interdigitated electrodes and metal interconnects) at an exposure energy of 120 mJ / cm². 2 After exposure, develop with AZ400K developer (diluted with deionized water at a ratio of 1:4) for 40 seconds to remove the photoresist from the exposed areas.
[0083] (9) Titanium of 10 nm and gold of 100 nm are deposited sequentially using an electron beam evaporation device. The photoresist and the titanium and gold covering the photoresist are removed by immersion in acetone for 30 minutes to form interdigitated electrodes and metal interconnects.
[0084] 2. Deposit a passivation layer on the area outside the interdigitated electrode region and the pad region of the metal interconnect of the ion gel capacitive gas sensing unit.
[0085] (1) Using atomic layer deposition technology, Al2O3 with a thickness of 50 nanometers is deposited at a temperature below 100℃.
[0086] (2) Photolithography and buffer oxide etchant wet etching process are used to selectively remove Al2O3 in the interdigitated electrode area and the pad area to form a passivation layer.
[0087] 3. Prepare a gas-sensitive layer in the interdigitated electrode region.
[0088] (1) The ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]), the polymer monomer hydroxyethyl acrylate (HEA) and the crosslinking agent polyethylene glycol diacrylate (PEGDA, Mn=250) were mixed in a mass ratio of 75:20:5. Then, 1.5 wt% of the photoinitiator Irgacure819 was added and the mixture was magnetically stirred for 2 hours under light-protected conditions until it was completely mixed.
[0089] (2) Spin-coating the precursor mixture solution with parameters set to 2000 rpm and 30 seconds to form a uniform liquid film with a thickness of about 1.5 micrometers.
[0090] (3) Cover the liquid film with a high-transmittance polyethylene terephthalate (PET) film to isolate oxygen.
[0091] (4) Use a mask to expose the area outside the interdigitated electrode area to perform ultraviolet exposure. The exposure parameters are wavelength 365 nm, intensity 10 mW / cm², and time 30 seconds, so that the mixed solution in the interdigitated electrode area undergoes photo-initiated polymerization reaction.
[0092] (5) After exposure, remove the PET film and immerse it in anhydrous ethanol for 10 seconds to remove the unpolymerized mixed solution in the unexposed area. Finally, a patterned solid ion gel film is formed in the interdigitated electrode area as a gas-sensitive layer.
[0093] When using the gas sensor prepared in Example 2 for gas detection, the workflow is as follows: The gas sensor is installed in a gas-sensitive test chamber, and a load resistor is connected in series with an external device via a probe station for protection. A constant DC bias voltage of 1 volt is applied to the oscillation circuit of the gas sensor using a semiconductor parameter analyzer. Simultaneously, the voltage pulse signal of the metal interconnect is monitored and recorded in real time using an oscilloscope.
[0094] At the start of the test, clean, dry air is first introduced into the test chamber, and the reference pulse frequency output by the gas sensor is measured and recorded. Then, a target gas (such as nitrogen dioxide) of a specific concentration (e.g., 20-100 ppm) is introduced into the test chamber. During this process, the bias voltage is kept constant, and the change in the output pulse frequency is monitored in real time. After the test is completed, the target gas is cut off, and clean air is introduced for purging until the pulse frequency output by the gas sensor returns to the reference value.
[0095] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.
Claims
1. A neuromorphic gas sensor based on ion gel and memristor, characterized in that, include: Ion gel capacitive gas sensing unit and Mott memristor; The ion gel capacitive gas sensing unit and the Mott memristor are heterogeneously integrated on the substrate using micro-nano fabrication technology and are electrically connected by metal interconnects to form an oscillation circuit. The ion gel capacitive gas sensing unit serves as the modulation capacitor in the oscillation circuit. It responds to changes in gas adsorption through the double-layer capacitance of the ion gel interface and modulates the charge-discharge cycle of the Mott memristor at room temperature to convert gas concentration information into the frequency of the output pulse signal, thereby realizing the integrated function of gas sensing and encoding. The ion gel capacitive gas sensing unit includes interdigitated electrodes and a gas-sensitive layer, wherein the interdigitated electrodes are electrically connected to the metal interconnects. The gas-sensitive layer is prepared by the following method: spin-coating a mixed solution of ionic liquid, polymer monomer, crosslinking agent, and photoinitiator to form a liquid film; covering the liquid film with an insulating film; and performing ultraviolet exposure using a mask that masks areas outside the interdigitated electrode region to induce a photo-initiated polymerization reaction in the mixed solution of the interdigitated electrode region. After exposure, the barrier film is removed and the mixed solution in the unexposed areas is removed to form a patterned solid ion gel film as the gas-sensitive layer.
2. The neuromorphic gas sensor based on ion gel and memristor according to claim 1, characterized in that, The substrate material is Si, Si / SiO2, quartz, or Al2O3.
3. The neuromorphic gas sensor based on ion gel and memristor according to claim 1, characterized in that, The Mott memristor includes electrodes and a resistive switching layer, the electrodes being electrically connected to the metal interconnect.
4. The neuromorphic gas sensor based on ion gel and memristor according to claim 3, characterized in that, The resistive switching layer is an electronically strongly correlated material with the characteristic of inducing metal-insulator phase transition by electric field or thermal excitation, and the thickness of the resistive switching layer is 100~500 nanometers.
5. The neuromorphic gas sensor based on ion gel and memristor according to claim 4, characterized in that, The electron strongly correlated material is VO2 or NbO2.
6. The neuromorphic gas sensor based on ion gel and memristor according to claim 1, characterized in that, The gas-sensitive layer is an ion gel film with a thickness of 500~2000 nanometers.
7. The neuromorphic gas sensor based on ion gel and memristor according to claim 6, characterized in that, The ion gel film includes an ionic liquid; The ionic liquid is an imidazole, pyridine, quaternary ammonium, quaternary phosphorus, pyrrolidine, or piperidine ionic liquid.
8. A method for preparing a neuromorphic gas sensor based on ion gel and memristor as described in any one of claims 1 to 7, characterized in that, Includes the following steps: An interdigitated electrode, a metal interconnect, and a Mott memristor are fabricated on a substrate for an ion gel capacitive gas sensing unit. The interdigitated electrode and the electrode of the Mott memristor are electrically connected to the metal interconnect to form an oscillating circuit. A passivation layer is deposited on the area outside the interdigitated electrode region of the ion gel capacitive gas sensing unit and the pad region of the metal interconnect. A gas-sensitive layer is prepared in the interdigitated electrode region.
9. The method for preparing a neuromorphic gas sensor based on ion gel and memristor according to claim 8, characterized in that, The fabrication of the interdigitated electrodes, metal interconnects, and Mott memristor of the ion-gel capacitive gas sensing unit on the substrate includes: A first mask is prepared by spin-coating photoresist and combining it with photolithography; the first mask covers the area other than the interdigitated electrodes, the metal interconnects and the two end electrodes of the Mott memristor. An adhesion layer material and an electrode metal material are deposited sequentially using electron beam evaporation. A stripping process is then used to remove the first mask and the adhesion layer material and the electrode metal material covering the first mask, forming the interdigitated electrode, the metal interconnect, and the two-end electrodes. VO2 was deposited in the electrode regions at both ends by magnetron sputtering, and then annealed to form a crystallized resistive switching layer.
10. The method for preparing a neuromorphic gas sensor based on ion gel and memristor according to claim 8, characterized in that, The fabrication of the interdigitated electrodes, metal interconnects, and Mott memristor of the ion-gel capacitive gas sensing unit on the substrate includes: A second mask is prepared by spin-coating photoresist and combining it with photolithography; the second mask covers the area outside the bottom electrode of the Mott memristor. An adhesion layer material and an electrode metal material are sequentially deposited using electron beam evaporation. A stripping process is then used to remove the second mask and the adhesion layer material and the electrode metal material covering the second mask, thereby forming the bottom electrode. NbO2 was deposited in the bottom electrode region by magnetron sputtering and then annealed to form a crystallized resistive switching layer. A third mask is prepared by spin-coating photoresist and combining it with photolithography; the third mask covers the area outside the top electrode of the Mott memristor. The adhesion layer material and the electrode metal material are deposited sequentially by electron beam evaporation, and the third mask and the adhesion layer material and electrode metal material covering the third mask are removed by a stripping process to form the top electrode; A fourth mask is prepared by spin-coating photoresist and combining it with photolithography; the fourth mask covers the area outside the interdigitated electrodes and the metal interconnects. The adhesion layer material and the electrode metal material are deposited sequentially by electron beam evaporation. The fourth mask and the adhesion layer material and the electrode metal material covering the fourth mask are removed by a stripping process to form the interdigitated electrode and the metal interconnect.
11. The method for preparing a neuromorphic gas sensor based on ion gel and memristor according to claim 8, characterized in that, The deposition of a passivation layer on the area outside the interdigitated electrode region of the ion gel capacitive gas sensing unit and the pad region of the metal interconnect includes: Deposition of passivation materials; The passivation material in the interdigitated electrode region and the pad region is selectively removed using photolithography and reactive ion etching processes to form the passivation layer.
12. The method for preparing a neuromorphic gas sensor based on ion gel and memristor according to claim 8, characterized in that, The fabrication of the gas-sensitive layer in the interdigitated electrode region includes: Spin-coating a mixed solution of ionic liquid, polymer monomer, crosslinking agent, and photoinitiator to form a liquid film; Cover the liquid film with an insulating film; Ultraviolet exposure is performed using a mask that covers the area outside the interdigitated electrode region, causing the mixed solution in the interdigitated electrode region to undergo a photo-initiated polymerization reaction; After exposure, the barrier film is removed and the mixed solution in the unexposed areas is removed to form a patterned solid ion gel film as the gas-sensitive layer.
13. An application of the neuromorphic gas sensor based on ionogel and memristor as described in any one of claims 1 to 7, characterized in that, The neuromorphic gas sensor based on ion gel and memristor is used to detect toxic and harmful gases; The toxic and harmful gases include: ammonia and nitrogen dioxide.