KR20230096446A - Electrospinning-based hydrogen-bonded hybrid nanofibrous membrane and pressure sensor and method for manufacturing the same - Google Patents

Abstract

An electrospinning-based hydrogen bond hybrid nanofiber membrane and a pressure sensor and a manufacturing method thereof are disclosed. A hybrid nanofibrous membrane manufacturing method according to an embodiment includes dispersing 2D nanomaterials in distilled water to create a precursor solution, using the precursor solution as a solvent, and adding a hydrophilic polymer to a hot plate generating a hydrophilic polymer-2D nanomaterial gel by stirring, adding an ion salt to the hydrophilic polymer-2D nanomaterial gel and then stirring it on a hot plate to produce an electrolyte solution, and electrospinning the electrolyte solution to obtain a 2D nanomaterial / creating a hydrophilic polymer / ionic salt hybrid nanofibrous membrane.

Description

Electrospinning-based hydrogen-bonded hybrid nanofibrous membrane and pressure sensor and method for manufacturing the same}

The present invention relates to a hybrid nanofiber membrane and a pressure sensor manufacturing technology using the same.

Nano fibers can be used in various devices and industries that develop new technologies such as controlled drug delivery systems, various sensors, supercapacitors, and energy harvesting. Existing hybrid nanofiber manufacturing methods have problems in that they are non-uniformly dispersed in a fiber matrix, resulting in a low surface area and easy aggregation.

Existing nanofiber membrane manufacturing methods have problems in that they are non-uniformly dispersed in the fiber matrix, resulting in low surface area and easy aggregation. This is a representative cause of deterioration of mechanical and electrical properties of materials.

According to an embodiment, a nanofiber membrane and a pressure sensor with greatly improved sensitivity and linearity range of the sensor and a manufacturing method thereof are proposed.

A hybrid nanofibrous membrane manufacturing method according to an embodiment includes dispersing 2D nanomaterials in distilled water to create a precursor solution, using the precursor solution as a solvent, and adding a hydrophilic polymer to a hot plate generating a hydrophilic polymer-2D nanomaterial gel by stirring, adding an ion salt to the hydrophilic polymer-2D nanomaterial gel and then stirring it on a hot plate to produce an electrolyte solution, and electrospinning the electrolyte solution to obtain a 2D nanomaterial / creating a hydrophilic polymer / ionic salt hybrid nanofibrous membrane.

The 2D nanomaterial may be any one of MXene, graphene, graphene oxide (GO), reduced graphene oxide (rGO), molybdenum disulfide (MoS ₂ ), and black phosphorus.

The hydrophilic polymer may be any one of poly(vinyl alcohol), poly(acrylamide), polyethylene glycol, and polyethylene oxide.

Ionic salts include lithium salt (Lithium bis(trifluoromethanesulfonyl)imide), potassium nitrate (KNO3), calcium nitrate (Ca(NO3)2), sodium chloride (NaCl), potassium bromide (KBr), cesium fluoride (CsF), nitric acid It may be any one of magnesium (Mg3N2) and calcium phosphate (Ca3P2).

A capacitive pressure sensor manufacturing method according to an embodiment includes the steps of electrospinning a mixture of a 2D nanomaterial and an ion salt in a hydrophilic polymer to create a hybrid nanofiber membrane dielectric layer, and centering on the hybrid nanofiber membrane dielectric layer and placing electrodes in a sandwich form on both sides to create a capacitive pressure sensor.

The hybrid nanofibrous membrane according to an embodiment is produced by electrospinning a mixture of a 2D nanomaterial and an ion salt in a hydrophilic polymer.

In the capacitive pressure sensor according to an embodiment, a hybrid nanofiber membrane dielectric layer produced by electrospinning a mixture of a 2D nanomaterial and an ion salt in a hydrophilic polymer, and a hybrid nanofiber membrane dielectric layer are sandwiched on both sides of the center It includes an electrode disposed as

In the capacitive pressure sensor, in the initial state where no pressure is applied, cation-anion pairs of ionic salts are attached to the functional group of the 2D nanomaterial of the hybrid nanofibrous membrane through hydrogen bonds (H-bonds), resulting in hybrid nanofibrous membrane and electrode interface It is possible to suppress the formation of an electric double layer in and reduce the initial capacitance value.

In a capacitive pressure sensor, when pressure is applied, the distance between the two electrodes decreases, increasing the strength of the electric field, which in turn initiates the process of ion pumping as the force applied to the particle under the influence of the electric field increases. As a result, the cation-anion pair of the ion salt is separated from the surface of the 2D nanomaterial, and an electric double layer having a predetermined thickness can be formed at the interface between the hybrid nanofibrous membrane and the electrode.

According to the nanofibrous membrane and pressure sensor according to an embodiment, by using a hybrid nanofibrous membrane made of a solution in which an ion salt of lithium sulfonamide and MXene are mixed in a polyvinyl alcohol elastic matrix as a sensing membrane, a hydrogen bond induced The functional layer on the surface of MXene can suppress the formation of an electrical double layer (EDL) in the electrode, thereby greatly reducing the initial capacitance value.

In addition, when external pressure is applied to the pressure sensor fabricated using the nanofiber membrane, a thick electric double layer is generated on the electrode through an ion pumping process triggered by the external pressure to greatly improve the capacitance change, resulting in a pressure sensor with ultra-high sensitivity. can provide.

Furthermore, by using a nanofiber polymer thin film manufactured by electrospinning technology, it is possible to obtain excellent performance in a wide range of pressures by having higher compressibility than conventional microstructured thin films.

1 is a view showing the flow of a hybrid nanofiber membrane manufacturing method according to an embodiment of the present invention;
2 is a view showing the MXene / PVA / LS hybrid nanofiber membrane concept according to an embodiment of the present invention;
3 is a diagram showing the flow of a method for manufacturing a capacitive pressure sensor according to an embodiment of the present invention;
4 is a diagram showing the concept of a PDMS electrode according to an embodiment of the present invention;
5 is a diagram showing the structure of a pressure sensor for capacitance according to an embodiment of the present invention;
6 is a view showing the interaction between MXene functional groups (-OH, -F and -O) and LS through hydrogen bonding of the hybrid nanofiber membrane-based pressure sensor according to an embodiment of the present invention;
7 is a view showing the operating principle of a hybrid nanofiber membrane-based pressure sensor under NP (No pressure) and UP (Under pressure) conditions according to an embodiment of the present invention;
8 shows (a) [TFSI-] anion characteristics, (b) [Li+] cation characteristics, and immobilization of ion pairs on the surface of MXene through the formation of hydrogen bonds and Coulomb attraction according to an embodiment of the present invention. A diagram showing hybrid nanospectral analysis,
9 shows (a) initial (NP) and final (UP) capacitance values of pressure sensors manufactured with various lithium salt concentrations, (b) pressure sensors manufactured with different concentrations of lithium salts according to an embodiment of the present invention. It is a diagram showing the change in the value of relative capacitance according to various pressures.

Advantages and features of the present invention, and methods for achieving them, will become clear with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, and only the present embodiments make the disclosure of the present invention complete, and common knowledge in the art to which the present invention belongs It is provided to fully inform the holder of the scope of the invention, and the present invention is only defined by the scope of the claims. Like reference numbers designate like elements throughout the specification.

In describing the embodiments of the present invention, if it is determined that a detailed description of a known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description will be omitted, and the terms described later will be used in the embodiments of the present invention. These terms are defined in consideration of the functions of and may vary depending on the user's or operator's intention or custom. Therefore, the definition should be made based on the contents throughout this specification.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the embodiments of the present invention exemplified below may be modified in many different forms, and the scope of the present invention is not limited to the embodiments described below. The embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art.

In the present invention, a hybrid nanofiber membrane is prepared by mixing an ionic salt of lithium sulfonamides and MXene in a poly (vinyl alcohol) elastomer matrix and then electrospinning and used as a sensing membrane.

A pressure sensor can be manufactured using a hybrid nanofiber membrane according to an embodiment, and in the pressure sensor, a functional layer on the surface of MXene caused by hydrogen bonding with an ion pair of an ion salt forms an electrical double layer (EDL) at the electrode. formation, greatly reducing the initial capacitance value.

When an external pressure is applied to the pressure sensor according to an embodiment, an ion pumping process is triggered by the external pressure, and a thick electrical double layer is generated on the electrode through the ion pumping to greatly improve capacitance change, resulting in ultra-high sensitivity. A pressure sensor of can be provided.

Furthermore, the pressure sensor according to an embodiment can obtain excellent performance in a wide range of pressures by using a nanofiber film manufactured by electrospinning technology, so that it has higher compressibility than conventional microstructured thin films.

Hereinafter, the hybrid nanofiber membrane and the pressure sensor having the above-described characteristics will be described later.

1 is a diagram showing the flow of a hybrid nanofiber membrane manufacturing method according to an embodiment of the present invention.

Referring to FIG. 1, 2D nanomaterial powder is dispersed in distilled water (DI Water) to create a precursor solution (110). 2D nanomaterials are mexene (MXene: Ti ₃ C ₂ T _x ), graphene, GO (Graphene Oxide), rGO (Reduced Graphene Oxide), molybdenum disulfide (MoS ₂ ), and black phosphorus. can be

Subsequently, hydrophilic polymer powder is added using the pre-solution as a solvent and stirred on a hot plate to produce a hydrophilic polymer-2D nanomaterial gel (120). The hydrophilic polymer may be any one of poly(vinyl alcohol), poly(acrylamide), polyethylene glycol, and polyethylene oxide.

Subsequently, after adding an ion salt to the hydrophilic polymer-2D nanomaterial gel according to a desired concentration, it is stirred on a hot plate to produce an electrolyte (S130). Ionic salts include lithium salt (Lithium bis(trifluoromethanesulfonyl)imide), potassium nitrate (KNO3), calcium nitrate (Ca(NO3)2), sodium chloride (NaCl), potassium bromide (KBr), cesium fluoride (CsF), magnesium nitrate (Mg3N2) and calcium phosphate (Ca3P2).

Subsequently, the electrolyte is electrospinned to produce a 2D nanomaterial/hydrophilic polymer/ionic salt hybrid nanofibrous membrane (HNM) (140).

The nanofibrous membrane manufactured by the electrospinning technique has higher compressibility than conventional microstructured thin films, and thus can obtain excellent performance in a wide range of pressures.

Due to its excellent physicochemical stability, high ionic conductivity, and high interfacial capacitance, nanofiber membranes using ion salts can be used in various fields such as lithium ion batteries, field effect transistors, supercapacitors, and capacitive pressure sensors. do.

2 is a diagram showing the concept of a MXene/PVA/LS hybrid nanofiber membrane according to an embodiment of the present invention.

Referring to FIG. 2, the PVA solution is mixed with MXene and LS, stirred, and then subjected to electrospinning to produce a hybrid nanofibrous membrane (HNM).

PVA is utilized for effective dissolution of LS and uniform dispersion of components throughout the polymer matrix, enhancing the ion transport properties of the sensing material and promoting electrical double layer (EDL) formation.

Ti ₃ C ₂ T _x MXene is an exceptional metal carbide 2D nanomaterial that is incorporated into the fabricated hybrid nanofibrous membrane to create an ion confinement effect. Due to the ionic confinement effect, the cation-anion pairs ([Li ⁺ ]-[TFSI ^- ]) of LS are attached to the functional groups of MXene nanosheets embedded in the hybrid nanofibrous membrane through H-bonds.

3 is a flow diagram illustrating a method for manufacturing a capacitive pressure sensor according to an embodiment of the present invention.

Referring to FIG. 3 , a capacitive pressure sensor can be manufactured using a hybrid nanofiber membrane.

To this end, a hybrid nanofiber film produced by electrospinning a mixture of a 2D nanomaterial and an ion salt is formed as a dielectric layer (310). Subsequently, a capacitive pressure sensor is created by disposing flexible/flexible electrodes having conductivity on both sides around the hybrid nanofiber membrane in a sandwich form (320). The flexible/flexible electrode may be made of a material such as a conductive thin film, conductive polymer, silver nano wire, CNT, or conductive paste. For example, a capacitive pressure sensor can be created by placing a MXene/PVA/LS hybrid nanofiber membrane in a sandwich structure between Au/M-polydimethylsiloxane (PDMS) electrodes.

A flexible pressure sensor can be fabricated using a hybrid nanofiber membrane. For example, a flexible pressure sensor in which initial capacitance is reduced by hydrogen bonding in a hybrid nanofibrous membrane and ion pumping is triggered when pressure is applied to increase final capacitance can be manufactured. Flexible pressure sensors have ultra-high sensitivity over a wide pressure range.

A wearable pressure sensor can be manufactured using a hybrid nanofiber membrane. The hybrid nanofiber-based pressure sensor detects various physiological and physical signals such as pulse, respiration, voice, and touch, and is widely used in smart medical/health care, sports, robots, automobiles, and the defense industry.

4 is a diagram illustrating the concept of a PDMS electrode according to an embodiment of the present invention.

Referring to FIG. 4, in order to manufacture an electrode for a pressure sensor, PDMS is put into an inexpensive sandpaper template and spin-coated to create sandpaper covered with PDMS, and the M-PDMS film is peeled off ( After peeling off), a Ti/Au layer is deposited on the microstructured surface through electron beam evaporation to create an Au/M-PDMS electrode.

5 is a diagram showing the structure of a pressure sensor for capacitance according to an embodiment of the present invention.

In more detail, (a) is a photograph of the fabricated nanofibrous membrane, (b) is a low-magnification FESEM image of the nanofibrous membrane, (c) is a single-layer and multi-layer low-resolution TEM image of MXene inside a polymer matrix, inset The left figure is a high-resolution TEM image of MXene, (d) a schematic diagram of the fabricated device, and the inset is a cross-sectional FESEM image (microstructured PDMS/hybrid nanofiber membrane/microstructured PDMS) of the fabricated capacitive pressure sensor. A FESEM image of a PDMS electrode deposited with microstructured Au using a sandpaper template, (e) a photograph of a manufactured capacitive pressure sensor.

6 is a diagram showing the interaction between MXene functional groups (-OH, -F and -O) and LS through hydrogen bonding of the hybrid nanofibrous membrane-based pressure sensor according to an embodiment of the present invention.

Referring to FIG. 6, the hybrid nanofiber membrane-based pressure sensor shows that the ([Li ⁺ ][TFSI ^- ]) ion pair of LS forms MXene functional groups (-OH, -F, and -O) and hydrogen bonds (H-bonds). coupled through Ion pairs are confined to the MXene surface through hydrogen bonding. As a result, the formation of an electrical double layer at the interface between the hybrid nanofiber membrane and the electrode is suppressed, and the initial capacitance value of the limited pressure sensor is reduced.

7 is a diagram showing the operating principle of a hybrid nanofiber membrane-based pressure sensor under NP (No pressure) and UP (Under pressure) conditions according to an embodiment of the present invention.

The inset of FIG. 7 is a diagram schematically illustrating a process occurring inside the nanofibrous membrane.

Referring to FIG. 7, in the hybrid nanofiber membrane-based pressure sensor, the ([Li ⁺ ][ ^TFSI- ]) ion pair of LS forms hydrogen bonds (H-bonds) with the MXene functional group in the initial state where no pressure is applied, thereby forming a MXene bonded to the surface. Then, when pressure is applied, ([Li ⁺ ][TFSI ^- ]) ion pairs are separated from the MXene surface due to the ion pumping phenomenon, creating a thick electrical double layer.

More specifically, in the hybrid nanofiber membrane-based pressure sensor, the [Li ⁺ ] cation of LS is bonded to the MXene surface containing MXene functional groups (-OH, -F, and -O) through hydrogen bonds (H-bonds). do. And the [TFSI ^- ] anion combines with the [Li ⁺ ] cation due to Coulomb's law to form a [Li ⁺ ] cation and [TFSI ^- ] anion pair. Before pressure is applied, ([Li ⁺ ][TFSI ^- ]) ion pairs are confined to the MXene surface through hydrogen bonding. As a result, the formation of an electrical double layer at the interface between the hybrid nanofiber membrane and the electrode is suppressed, and the initial capacitance value of the limited pressure sensor is reduced.

When pressure is applied, the pressure sensor decreases the distance between the two electrodes, increasing the electric field strength and consequently increasing the force applied to the particle under the influence of the electric field. By this phenomenon, the pressure sensor initiates an ion pumping process where ([Li ⁺ ][TFSI ^- ]) ion pairs are separated from the MXene surface to form a thick electrical double layer at the hybrid nanofibrous membrane and electrode interface. This increases the relative change in capacitance.

The right picture of FIG. 7 is a diagram showing the Helmholtz model before and after introducing nanoparticles into an ionic electrolyte. The pressure sensor model containing nanoparticles in the ionic liquid (modified model) shows lower initial capacitance and higher sensitivity than the traditional mode.

8 shows the immobilization of ion pairs on the surface of MXene through the formation of (a) [TFSI ^- ] anion characteristics, (b) [Li ⁺ ] cation characteristics, hydrogen bonds and Coulomb attraction according to an embodiment of the present invention. It is a diagram showing hybrid nano-spectral analysis in

Referring to (a), the red-shifts of the expansion-contraction modes of the [ ^TFSI- ] anion at ~742 cm ⁻¹ assigned to the NSO, SN, CF and FCS vibrations can be performed as follows. Due to the electrostatic attraction between the ([Li ⁺ ][TFSI ^- ]) ion pair and the MXene functional group, the ([Li ⁺ ][TFSI ^- ]) ion pair is confined.

Referring to (b), blue-shifts of Li ⁺ Raman vibrational modes observed for LS(60)-MXene-PVA (SO ₂ stretching, CF ₃ stretching, N-CH stretching and CH ₂ stretching) further suggests the existence of hydrogen bonding interactions with MXene functional groups.

9 shows (a) initial (NP) and final (UP) capacitance values of pressure sensors manufactured with various lithium salt concentrations, (b) pressure sensors manufactured with different concentrations of lithium salts according to an embodiment of the present invention. It is a diagram showing the change in the value of relative capacitance according to various pressures.

Referring to (a), ^all LS-MXene-PVA pressure sensors show a negligible capacitance ^difference (e.g. LS For (60)-MXene-PVA, low initial capacitance (C ₀ ) values are obtained (C ₀ = 20 ± 2.7 pF).

However, under pressure (UP) condition (~200 kPa), the C _p value is the same for all LS-MXene-PVA pressure sensors (e.g. C _p = 8761.6 ± 178.7 pF for _LS (60)-MXene-PVA). This C is significantly higher than ₀ . The overall sensor structure, induced by the applied pressure, consequently increases the electrostatic force applied to the particle under the influence of an external electric field. This process triggers the cleavage of hydrogen bonds between the ionic and MXene functional groups, ultimately strengthening the EDL at the electrode/electrolyte interface.

Referring to (b), the relative capacitance changes observed for the LS-MXene-PVA pressure sensors with LS concentrations of 20%, 40%, and 60% are the highest output obtained from the LS(60)-MXene-PVA sensor. Shows the high pressure sensing function.

So far, the present invention has been looked at mainly by its embodiments. Those skilled in the art to which the present invention pertains will be able to understand that the present invention may be implemented in a modified form without departing from the essential characteristics of the present invention. Therefore, the disclosed embodiments should be considered from a descriptive point of view rather than a limiting point of view. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the equivalent scope will be construed as being included in the present invention.

Claims (9)

dispersing the 2D nanomaterial in distilled water to create a precursor solution;
Generating a hydrophilic polymer-2D nanomaterial gel by adding a hydrophilic polymer to the pre-solution as a solvent and then stirring on a hot plate;
generating an electrolyte solution by adding an ionic salt to the hydrophilic polymer-2D nanomaterial gel and then stirring it on a hot plate; and
electrospinning the electrolyte to produce a 2D nanomaterial/hydrophilic polymer/ionic salt hybrid nanofiber membrane;
Hybrid nanofiber membrane manufacturing method comprising a. The method of claim 1, wherein the 2D nanomaterial is
Mexene (MXene), graphene (graphene), GO (Graphene Oxide), rGO (Reduced Graphene Oxide), molybdenum disulfide (MoS ₂ ) and black phosphorus (black phosphorus) hybrid nanofiber membrane manufacturing method, characterized in that any one . The method of claim 1, wherein the hydrophilic polymer
Hybrid nanofiber characterized by being any one of poly (vinyl alcohol), poly (acrylamide), polyethylene glycol (poly (ethylene glycol)), and polyethylene oxide Membrane manufacturing method. The method of claim 1, wherein the ionic salt is
Lithium salt (Lithium bis(trifluoromethanesulfonyl)imide), potassium nitrate (KNO ₃ ), calcium nitrate (Ca(NO ₃ ) ₂ ), sodium chloride (NaCl), potassium bromide (KBr), cesium fluoride (CsF), magnesium nitrate ( Mg ₃ N ₂ ), calcium phosphate (Ca ₃ P ₂ ) Hybrid nanofiber membrane manufacturing method, characterized in that any one. electrospinning a mixture of a hydrophilic polymer with a 2D nanomaterial and an ionic salt to produce a hybrid nanofiber membrane dielectric layer; and
creating a capacitive pressure sensor by arranging electrodes in a sandwich form on both sides of the hybrid nanofiber membrane dielectric layer;
A capacitive pressure sensor manufacturing method comprising a. A hybrid nanofibrous membrane produced by electrospinning a mixture of 2D nanomaterials and ionic salts in a hydrophilic polymer. A hybrid nanofiber membrane dielectric layer produced by electrospinning a mixture of a hydrophilic polymer with a 2D nanomaterial and an ionic salt; and
Electrodes disposed in a sandwich form on both sides of the hybrid nanofiber membrane dielectric layer as a center;
A capacitive pressure sensor comprising a. The method of claim 7, wherein the capacitive pressure sensor
In the initial state where no pressure is applied, the cation-anion pairs of the ion salt are attached to the functional group of the 2D nanomaterial of the hybrid nanofibrous membrane through hydrogen bonds (H-bonds), suppressing the formation of an electric double layer at the interface between the hybrid nanofibrous membrane and the electrode. And, a capacitance type pressure sensor characterized in that the initial capacitance value is reduced. The method of claim 8, wherein the capacitive pressure sensor
When pressure is applied, the distance between the two electrodes decreases, increasing the electric field strength and consequently increasing the force exerted on the particle under the influence of the electric field, initiating the process of Ion Pumping to form cation-anion pairs of ionic salts. A capacitive pressure sensor characterized in that it is separated from the surface of the 2D nanomaterial and forms an electrical double layer of a predetermined thickness at the interface between the hybrid nanofiber membrane and the electrode.

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