A meniscus memristor based on droplet control and its preparation method and application

Abstract

The present invention belongs to the field of micro-nanofluidics, and specifically discloses a meniscus fluid memristor based on droplet regulation, and its preparation method and application. The meniscus memristor includes a nanopore chip and two concave-convex fittings for clamping the chip, both fittings having a liquid reservoir for containing liquid and a groove for placing the chip. The liquid reservoirs are used to contain a first liquid and a second liquid respectively, and the two liquids are immiscible with each other and have different surface tension coefficients. On one side of the thinned area of ​​the nanopore chip, the first liquid and the second liquid contact and form a curved liquid surface. By applying a voltage to the memristor and thereby regulating the size of the meniscus droplets, the resistance value of the nanopore orifice is changed, and finally the resistance value change function of the memristor is realized. The present invention uses the first liquid and the second liquid to form a curved liquid surface droplet on one side of the nanopore thinned area and uses an electric field to realize droplet regulation, thereby realizing resistance change, thereby constructing a meniscus fluid memristor based on droplet regulation.

Description

Technical Field

[0001] The present invention relates to the field of micro-nanofluid technology, and in particular to a meniscus memristor based on droplet regulation, and a preparation method and application thereof. Background Art

[0002] In the 1970s, Professor Shao-Tang Tsai proposed a fourth fundamental passive electronic device, naming it the memristor, which describes the relationship between charge and magnetic flux. It wasn't until 2008 that HP Labs fabricated the first memristor based on metal oxides. In recent years, memristor technology has rapidly advanced, with a variety of memristors emerging, including metal oxide memristors, organic memristors, and fluidic memristors. The unique memristive properties of memristors hold great potential in fields such as biomimetic synaptic devices and neuromorphic computing.

[0003] Compared to solid-state memristors, fluid memristors offer advantages such as low cost, high controllability, and a gradual resistance change. They also hold broad application prospects in artificial synapses and neuromorphic computing. However, current fluid memristor device fabrication processes are complex and yield low, while performance suffers from slow response and high power consumption. Therefore, there is a need to develop a new type of fluid memristor with simpler fabrication, faster response, and lower power consumption. Summary of the Invention

[0004] To address these issues, the present invention discloses a droplet-controlled meniscus fluid memristor. This memristor modulates the resistance of a nanopore orifice by manipulating a meniscus droplet formed by two immiscible liquids using an electric field, thereby achieving resistance variation and control. This memristor exhibits fast response, low power consumption, and simple fabrication, facilitating large-scale manufacturing and application.

[0005] To achieve the above objectives, the present invention provides a meniscus fluid memristor based on droplet manipulation, comprising a nanopore chip and a polymethyl methacrylate (PMMA) workpiece for mounting the chip. Both workpieces have a reservoir for holding liquid and a groove for accommodating the chip. The nanopore chip is placed in the groove and communicates with a first reservoir and a second reservoir at either end of the workpiece.

[0006] The first liquid is injected into a first liquid reservoir and connected to a first electrode; the second liquid is injected into a second liquid reservoir and connected to a second electrode; the first liquid and the second liquid are mutually immiscible and can form a clear interface when in contact; there is a difference in surface tension coefficient between the first liquid and the second liquid; the first liquid and the second liquid form meniscus droplets in the thinned area of ​​the nanopore chip, and carriers of corresponding electrical properties accumulate on the contact surface and in the droplets under the action of an applied voltage;

[0007] In addition, the first electrode and the second electrode are used to apply a control signal or a read signal to the liquid reservoir; the control signal is used to apply a control voltage to both ends of the nanopore. Under the action of the control electric field, the size of the meniscus droplet formed by the first liquid and the second liquid on one side of the nanopore changes, thereby causing the pore resistance of the nanopore to change based on the difference in electrical conductivity between the first liquid and the second liquid, thereby realizing the resistance change function of the memristor;

[0008] The signal reading function is used to apply a small voltage to both ends of the nanopore, and determine the resistance value of the nanopore by reading the current signal, thereby realizing the reading function of the memristor.

[0009] The method for preparing the meniscus memristor comprises the following steps:

[0010] Step 1: Fabricate nanopores using a chip with a suspended film structure;

[0011] Step 2: Use the processed parts to clamp the nanopore chip.

[0012] Furthermore, the nanopore is formed by using focused ion beam machining (FIB) technology or dielectric poration technology.

[0013] Furthermore, polymethyl methacrylate (PMMA) workpieces were manufactured using a 3D printing process.

[0014] Furthermore, the packaging step specifically includes positioning the nanopore chip using a groove of a processed part and fixing and sealing it using prepared polydimethylsiloxane (PDMS).

[0015] Furthermore, the liquid injection step is specifically to use a fine needle to inject the first liquid and the second liquid into the first liquid reservoir and the second liquid reservoir respectively, to ensure that the liquids are connected through the nanopore chip and form a clear curved liquid surface.

[0016] Beneficial effects of the present invention:

[0017] 1. In the present invention, by applying an external voltage, the meniscus droplet portion formed by two immiscible solutions on one side of the nanopore is regulated, thereby realizing the resistance change function of the memristor.

[0018] 2. Due to the high surface area ratio of the nanopore, a small change in the crescent droplet can also cause a large change in resistance, thereby achieving the advantages of fast response and low power consumption of the memristor.

[0019] 3. The meniscus droplet is regulated by an external voltage, and theoretically a fully controllable and continuous resistance change can be achieved, with a very small variance of the device.

[0020] 4. The present invention prepares nanopores based on focused ion beam processing technology or dielectric perforation technology, and prepares clamping parts based on 3D printing technology, which greatly reduces the difficulty of preparing fluid memristors and provides a basis for large-scale production and application of fluid memristors.

[0021] 5. As a nanofluidic artificial synaptic device, the curved liquid surface memristor of the present invention can not only realize the basic functions of a neural synaptic device, but also respond quickly to stimulation signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 1 is a device structure diagram of the curved liquid surface memristor of the present invention.

[0023] Figure 2 This is a schematic diagram of the principle of nanofluidic devices as memristors.

[0024] Figure 3 It is a chip with a suspended film structure, and the 5um area is a thinning area used to prepare nanopores.

[0025] Figure 4 This is a current-voltage characteristic diagram of the power generation performance of the curved liquid surface memristor obtained by the present invention tested using a patch clamp.

[0026] Figure 5 This is a resistive switching characteristic test diagram of the device prepared by the present invention, where the set voltage is 500mV, the reset voltage is -500mV, and the pulse width is 500ms.

[0027] Figure 6 This is a resistance retention characteristic diagram of the present invention.

[0028] List of reference numerals:

[0029] 1 is the electrode, 2 is the liquid reservoir, 3 is the nanopore chip, and 4 is the polymethyl methacrylate (PMMA) processing part. DETAILED DESCRIPTION

[0030] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. It should be noted that the terms "front," "rear," "left," "right," "up," and "down" used in the following description refer to directions in the accompanying drawings, and the terms "inward" and "outward" refer to directions toward or away from the geometric center of a particular component, respectively.

[0031] Example 1

[0032] like Figure 1As shown, the meniscus memristor in this embodiment has polymethyl methacrylate (PMMA) workpieces 4 at both ends. These workpieces contain reservoirs 2 for holding liquid and recesses for accommodating the chip. A nanopore chip 3, connected to the reservoirs, is fabricated using a focused ion beam process.

[0033] The right reservoir of the device is filled with KCl solution (the concentration of the KCl solution can be, for example, 1M), while the left reservoir is filled with an ionic liquid (e.g., 1-Butyl-3-methylimidazolidinone hexafluorophosphate, [BM IM][PF6]). Because the ionic liquid is much more viscous than the KCl solution, the nanopore is filled with KCl solution. Due to the thinned region on the nanopore chip, a meniscus and a crescent droplet appear on the side facing the ionic liquid. Under the action of a voltage, the meniscus droplet becomes polarized, and carriers of corresponding electrical properties accumulate near the meniscus, generating a net charge of opposite polarity within the crescent droplet. Driven by the voltage, the friction generated by the carrier movement drives the crescent droplet to change. The nanopore mouth resistance changes due to changes in the conductivity of the solution near the pore. Changes in the crescent droplet lead to changes in the mouth resistance, and thus to changes in the overall resistance.

[0034] The meniscus fluid memristor can be processed using a method comprising the following steps:

[0035] 1) Preparation of nanopore chips with suspended film structures: Figure 3 As shown, a 1 μm silicon oxide insulating layer is grown on both sides of a 200 μm double-sided polished silicon wafer by a thermal oxidation process; a 100 nm silicon nitride layer is grown on the silicon oxide layer by a low-pressure chemical vapor deposition process (LP-CVD); a thinning area with a diameter of 5 μm is etched in the silicon nitride layer by reactive ion etching (RIE), and the thickness of the silicon nitride layer in the thinning area is about 20 nm; RIE is used to etch the other side to expose the silicon substrate and the silicon substrate is wet-etched with a KOH solution to form a self-supporting silicon nitride-silicon oxide suspended membrane; finally, the silicon oxide layer is etched by a buffered oxide solution (BOE) to confirm that only the silicon nitride film structure is retained.

[0036] 2) Preparation of nanopores: Figure 1 As shown, a nanopore of a memristor is designed and processed. The nanopore is processed on a silicon nitride chip by a focused ion beam process (FIB), and a silicon nitride hole with a length of 20nm and a radius of 1-500nm is prepared.

[0037] The shape parameters of a single workpiece can be set as follows: the internal liquid reservoir is a cylinder with a radius of 1 mm and a depth of 2 mm, and the groove is a cylinder with a diameter of about 5 mm and a depth of about 2 mm; and it is processed using polymethyl methacrylate (PMMA).

[0038] 3) Device Encapsulation and Liquid Injection: Under a microscope, the nanopore chip was embedded in the groove and clamped. It was then fixed and encapsulated using prepared polydimethylsiloxane. A fine needle was used to inject KCl solution into the right reservoir and ionic liquid into the left reservoir, ensuring that the two liquids were connected through the nanopore.

[0039] The current-voltage characteristic curve of the curved liquid surface memristor prepared in this example is shown in the figure. Figure 3 As shown, when the voltage is applied, the electrode on the KCl solution side is grounded.

[0040] Figure 4 The test diagram of the resistive switching performance of the curved liquid surface memristor prepared for this example: a control voltage (500mV, 500ms) was applied to the electrode on one side of the ionic liquid 15 times. The left side shows continuous enhancement, and the right side shows continuous suppression. It can be seen that the multi-resistance state characteristics of the memristor are good. The set voltage is 500mV and the reset voltage is -500mV. Of course, the specific amplitude of the control voltage can also be flexibly adjusted according to the specific type of solution selected and the specific parameters of the nanopore. For example, a voltage of 100 to 1000mV can be used as the set voltage, and a voltage of -100 to -1000mV can be used as the reset voltage. The pulse width can be other values ​​in the range of 10 to 1000ms in addition to 500ms.

[0041] In addition to the KCl solution and [BMI M][PF6] ionic liquid used in the above embodiment, other conductive liquids can also be used, as long as there is a difference in surface tension coefficient between the first liquid and the second liquid and they are immiscible.

[0042] like Figure 5 The resistive switching characteristic test diagram of the device prepared by the present invention shows that the set voltage is 500mV, the reset voltage is -500mV, and the pulse width is 500ms. Figure 6 This is the resistance retention characteristic diagram of the present invention. It can be seen that the device prepared by the present invention can achieve continuous and controllable resistance value changes and the device retention is excellent.

[0043] The technical means disclosed in the solution of the present invention are not limited to the technical means disclosed in the above-mentioned embodiment, but also include technical solutions composed of any combination of the above technical features.

Claims

1. A meniscus fluid memristor based on droplet control, characterized in that: The invention comprises a nanopore chip and two polymethyl methacrylate (PMMA) workpieces for clamping the nanopore chip, wherein one of the workpieces is provided with a first liquid reservoir for containing a first liquid; the other workpiece is provided with a second liquid reservoir for containing a second liquid; each of the workpieces is provided with a groove for placing the chip; wherein the nanopore chip is placed in the groove of the workpiece and clamped, and both ends of the nanopore chip are connected to the liquid reservoir of the workpiece; a first electrode is connected to the first liquid; a second electrode is connected to the second liquid; there is a difference in surface tension coefficient between the first liquid and the second liquid and they are immiscible with each other; wherein on one side of the thinning area of ​​the nanopore chip, the first liquid contacts the second liquid and forms a meniscus; by applying voltage to the memristor and thereby regulating the size of the meniscus droplet, the resistance value of the nanopore mouth is changed, and finally the resistance value change function of the memristor is realized.

2. The meniscus fluid memristor based on droplet control according to claim 1, characterized in that: The nanopore is a silicon nitride nanopore or a silicon dioxide nanopore, the nanopore length is 20 nm, and the nanopore radius is 1-500 nm.

3. The meniscus fluid memristor based on droplet control according to claim 1, characterized in that: The first liquid and the second liquid are immiscible with each other and can form a clear interface when they come into contact.

4. The meniscus fluid memristor based on droplet control according to claim 1, characterized in that: There is a difference in surface tension coefficient between the first liquid and the second liquid.

5. The meniscus fluid memristor based on droplet control according to claim 1, characterized in that: The first liquid and the second liquid form a crescent-shaped contact surface. Under the action of an applied voltage, carriers of corresponding electrical properties accumulate on the contact surface and in the crescent droplet. The applied voltage range is 500±mV.

6. The method for preparing a meniscus fluid memristor based on droplet control according to any one of claims 1 to 5, characterized in that: The following steps are involved: Step 1: Fabricate nanopores using a chip with a suspended film structure; Step 2: Use the processed parts to clamp the nanopore chip.

7. The method for preparing a meniscus fluid memristor based on droplet control according to claim 6, characterized in that: The nanopore is formed by using focused ion beam processing (FIB) technology or dielectric perforation technology; and the clamping liquid pool is completed by using a 3D printing process.

8. The method for preparing a meniscus fluid memristor based on droplet control according to claim 6, characterized in that: The packaging specifically involves positioning the nanopore chip using grooves in the processed parts and fixing and sealing it with prepared polydimethylsiloxane (PDMS).

9. The method for preparing a meniscus fluid memristor based on droplet control according to claim 6, characterized in that: A fine needle is used to inject the first liquid and the second liquid into the first liquid reservoir and the second liquid reservoir respectively, ensuring that the liquids are connected through the nanopore chip and form a clear curved liquid surface.

10. Application of meniscus fluid memristor based on droplet control, characterized in that: As a nanofluidic neural synaptic device, it can realize synaptic response and neural-like computing functions.

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