KR20220049954A - Thin film based cachogenide for sensor and method for manufacturing the same - Google Patents

Abstract

The present invention relates to a thin film for a sensor applicable as a strain sensor or a temperature sensor and a method for manufacturing the same, and more specifically, to a thin film for a sensor to which a silver (Ag)-based chalcogenide compound is applied by supporting silver nanocrystals (AgNCs) in a chalcogen compound solution. According to one aspect of the present invention, the thin film for a sensor can be used as a high-sensitivity strain sensor and a temperature sensor by converting the metal nanocrystals into semiconductors.

Description

Thin film for chalcogenide-based sensor and manufacturing method thereof

The present invention relates to a thin film for a sensor applicable as a strain sensor or a temperature sensor and a method for manufacturing the same, and more particularly, by supporting silver nanocrystals (AgNCs) in a chalcogen compound solution, a silver (Ag)-based chalcogenide It relates to a thin film for a sensor to which a compound is applied.

With the recent development of the Internet of Things (IoT) and increased interest in personal health, the wearable sensor market is rapidly growing. Among them, research on a wearable temperature sensor capable of monitoring a user's health status by electrically converting sensitive biosignals such as human body movement and pulse is being actively conducted. However, sensors up to now have limitations in that they cannot sensitively detect a living body or have low reliability due to low sensitivity. In addition, since most sensors are manufactured through expensive processes such as complicated processes, high temperature, and vacuum processes, their limitations are obvious because they are universally used. Accordingly, there is an urgent need for a wetting method that can economically mass-produce high-sensitivity wearable sensors.

Republic of Korea Patent Publication No. 10-2015-0106152

An object of the present invention is to provide a sensor capable of detecting a live signal by improving sensitivity, manufacturing a simple process, and capable of general use.

In order to achieve the object to be solved, a thin film for a sensor according to an aspect of the present invention includes a substrate and; It includes a silver (Ag) nanocrystal-based chacogenide compound formed on the substrate.

The substrate may be a flexible substrate, and the substrate may be polyethylene terephthalate (PET), polyimide (PI), or polydimethyl siloxane (PDMS).

The silver nanocrystals may have a particle diameter of 3 to 15 nm.

The chalcogenide compound may be Ag ₂ E (E = Se or S), preferably, the chalcogenide compound may be Ag ₂ Se.

In addition, the strain sensor according to one embodiment of the present invention includes the above-described thin film for the sensor.

In addition, the temperature sensor according to one embodiment of the present invention includes the above-described sensor thin film.

In addition, the method of manufacturing a thin film for a sensor according to an aspect of the present invention comprises the steps of preparing a silver (Ag) nanocrystal solution; providing a silver nanocrystal thin film by coating the silver (Ag) nanocrystal solution on a substrate; and supporting the silver nanocrystal thin film in a chalcogen precursor solution.

The silver (Ag) nanocrystal solution may be one in which silver nanocrystals are dispersed in a non-polar solvent.

The silver (Ag) nanocrystals may have a particle diameter of 3 to 15 nm.

The concentration of the silver (Ag) nanocrystal solution may be 50 to 200 mg/mL.

The silver (Ag) nanocrystal thin film may be formed by spin coating the silver nanocrystal solution on the substrate.

The substrate may be a flexible substrate, and the substrate may be polyethylene terephthalate (PET), polyimide (PI), or polydimethyl siloxane (PDMS).

The chalcogen element of the chalcogen precursor may be selenium (Se) or sulfur (S).

The loading time of the silver nanocrystal thin film may be 30 seconds (s) to 3 minutes (min).

According to one aspect of the present invention, there is an effect that can be used as a high-sensitivity strain and temperature sensor by converting the metal nanocrystals into semiconductors.

In addition, since it can be manufactured at room temperature and a solution process, there is an effect of reducing manufacturing cost and enabling mass production.

In addition, there is an effect that can be applied to various fields such as a wearable sensor platform.

Figure 1 shows a schematic diagram of the conversion from silver nanocrystals (AgNCs) to Ag ₂ Se according to an embodiment of the present invention.
Figure 2 shows the results of EDX (Energy Dispersive X-ray spectroscopy) and X-ray diffraction (X-ray diffraction) analysis of the surface of the thin film according to the chalcogen precursor solution loading time of the AgNCs thin film according to an embodiment of the present invention. will be.
3 shows transmission electron microscopy (TEM) and scanning electron microscopy (SEM) images of the thin film according to the lapse of the deposition time according to an embodiment of the present invention.
4 is a resistance change according to a temperature change from 100 K to 300 K for a thin film according to an embodiment of the present invention, and a relative resistance change according to repeated temperature changes of 25 ℃ (298 K) and 75 ℃ (348 K) will show

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings and contents described in the accompanying drawings, but the present invention is not limited or limited by the embodiments.

The terminology used herein is for the purpose of describing the embodiments and is not intended to limit the present invention. In this specification, the singular also includes the plural unless specifically stated otherwise in the phrase. As used herein, "comprises" and/or "comprising" refers to the presence of one or more other components, steps, operations and/or elements mentioned. or addition is not excluded.

As used herein, “embodiment”, “example”, “aspect”, “exemplary”, etc. are to be construed as advantageous in any aspect or design described as being preferred or advantageous over other aspects or designs. is not doing

The terms used in the description below are selected as general and universal in the related technical field, but there may be other terms depending on the development and/or change of technology, customs, preferences of technicians, and the like. Therefore, the terms used in the description below should not be understood as limiting the technical idea, but should be understood as exemplary terms for describing the embodiments.

In addition, in a specific case, there is a term arbitrarily selected by the applicant, and in this case, the meaning will be described in detail in the corresponding description. Therefore, the terms used in the description below should be understood based on the meaning of the term and the content throughout the specification, not the simple name of the term.

Meanwhile, terms such as first and second may be used to describe various components, but the components are not limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

Further, when a part such as a film, layer, region, configuration request, etc. is said to be “on” or “on” another part, not only when it is directly on the other part, but also another film, layer, region, or component in the middle It includes cases where etc. are interposed.

Unless otherwise defined, all terms (including technical and scientific terms) used herein may be used with the meaning commonly understood by those of ordinary skill in the art to which the present invention belongs. In addition, the terms defined in the dictionary used in general are not to be interpreted ideally or excessively unless clearly specifically defined.

Meanwhile, in describing the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. In addition, the terms used in this specification are terms used to properly express an embodiment of the present invention, which may vary according to the intention of a user or operator, or a custom in the field to which the present invention belongs. Accordingly, definitions of these terms should be made based on the content throughout this specification.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

A thin film for a sensor according to one embodiment of the present invention comprises: a substrate; and silver (Ag) nanocrystals (AgNCs)-based chacogenide compounds formed on the substrate.

The substrate may be a flexible substrate, and the substrate may be polyethylene terephthalate (PET), polyimide (PI), polydimethyl siloxane (PDMS), a silicon wafer, or glass.

The silver nanocrystals may have a particle diameter of 3 to 15 nm, preferably 5 nm.

The chalcogenide compound may be Ag ₂ E (E = Se or S), preferably, the chalcogenide compound may be Ag ₂ Se. Ag ₂ E (E=Se or S) chalcogenide compound has a low bandgap (bandgap), can perform a function as a thermoelectric element.

In addition, the strain sensor according to one embodiment of the present invention includes the thin film for the sensor, and the strain sensor may be a flexible sensor.

In addition, the temperature sensor according to one embodiment of the present invention includes a sensor thin film.

A method of manufacturing a thin film for a sensor according to one embodiment of the present invention includes the steps of preparing a silver (Ag) nanocrystal (AgNCs) solution (S100); coating the silver (Ag) nanocrystal solution on a substrate to provide a silver nanocrystal thin film (S200); and supporting the silver nanocrystalline thin film in a chalcogen precursor solution (S300).

The silver (Ag) nanocrystal solution may be a dispersion of silver nanocrystals in a non-polar solvent, and the non-polar solvent may be n-octane or hexane.

The concentration of the silver (Ag) nanocrystal solution may be 50 to 200 mg/mL, preferably 200 mg/mL.

The silver nanocrystals may have a particle diameter of 3 to 15 nm, preferably 5 nm.

The silver (Ag) nanocrystal thin film may be formed by spin-coating the silver nanocrystal solution on the substrate.

The substrate may be a flexible substrate, and the substrate may be polyethylene terephthalate (PET), polyimide (PI), polydimethyl siloxane (PDMS), a silicon wafer, or glass.

The substrate may be a self-assembled monolayer (SAM) introduced, and the self-assembled single thin film may be formed by using the substrate as MPTS (((3-mercaptopropyl) trimethoxysilane), APTES (3-aminopropyltriethoxysilane) or phosphoric acid. It may be introduced by supporting it in (phophonic acid), in which case the concentration of MPTS (((3-mercaptopropyl) trimethoxysilane), APTES (3-aminopropyltriethoxysilane) or phosphoric acid may be 3 to 8 vol%.

The chalcogen element of the chalcogen precursor may be selenium (Se) or sulfur (S), and the chalcogen precursor may be Na ₂ E (E=Se or S).

The concentration of the chalcogen precursor solution may be 1 mM to 50 mM, when it is less than 1 mM, it is not easy to replace the chalcogenide compound in silver nanocrystals, and when it exceeds 50 mM, delamination from the substrate (delamination) ) may occur. More preferably, the concentration of the chalcogen precursor solution may be 10 mM.

The loading time of the silver nanocrystal thin film may be 30 seconds (s) to 3 minutes (min), preferably 3 minutes (min).

1 is a schematic diagram showing the conversion of AgNCs to Ag 2 Se in the method for manufacturing a thin film for a sensor of the present invention. Referring to FIG. 1 , AgNCs are converted to Ag ₂ Se while being supported in a chalcogenide precursor solution. Through this, as Ag ₂ Se is formed, a new crystal structure is formed.

Hereinafter, the present invention will be described in more detail through examples. These Examples are for explaining the present invention in more detail, and the scope of the present invention is not limited by these Examples.

ready yes. Preparation of Materials

Sodium selenide (Na ₂ Se, 99.8%), silver nitrate (AgNO ₃ , 99%) and n-octane (98+%) were obtained from Alfa Aesar Co,. It was purchased from Inc. Oleylamine (OAm, 70%), oleic acid (OA, 90%), hexane (99%), methanol (99.8%) and MPTS ((3-mercaptopropyl)trimethoxysilane, 95% ) was purchased from Sigma Aldrich Co., Ltd. For use as a flexible device, a PET (polyethylene terephthalate) film with a thickness of 250 μm was purchased from SK films.

Preparation Example 1. Synthesis of silver nanocrystals (AgNCs; silver nanocrystals)

3.5 g of silver nitrate (AgNO ₃ ) powder, 90 mL of oleic acid (OA) solution, and 6 mL of oleylamine (OAm) solution were mixed in a round bottom three-neck flask using magnetic stirring. . The mixed solution was heated to 343 K and degassed under vacuum for 90 minutes (min). After degassing, the temperature of the mixed solution was raised to 453 K at a temperature increase rate of 3 K per 3 min (min) (1 K/1 min (min)). Thereafter, the mixed solution is cooled to ambient temperature. Thereafter, the synthesized AgNCs were obtained by washing through a centrifugation process in which toluene and ethanol were added, and the washing process was repeated 5 times. Finally, the synthesized AgNCs have a diameter of 5 nm, and the synthesized AgNCs are dispersed in hexane at a concentration of 50 to 200 mg/mL.

Preparation Example 2. Preparation of a substrate

For all kinds of substrates (PET, silicon wafer, glass), acetone, iso-propyl alcohol, de-ionized (de-ionized ( DI) water) in the order of washing. Thereafter, the substrate is treated with UV-ozone. Finally, all substrates were immersed in a 5 vol% MPTS solution to form a self-assembled monolayer (SAM) on the substrate to improve adhesion between AgNCs and the substrate.

Example.

The AgNCs synthesized in Preparation Example 1 were spin-coated on the substrate prepared in Preparation Example 2 under the concentration conditions shown in Table 1 below at a speed of 1000 rpm for 30 seconds (s) to prepare an AgNCs thin film do.

Prepare a 10 mM Na ₂ Se solution in methanol (methanol) solvent. The AgNCs thin film was supported on the NaSe solution for 30 seconds to 5 minutes (min) according to Table 1 below. Thereafter, the thin film is washed several times with methanol to remove excess Na2Se on the thin film surface.

Table 1 below summarizes the concentration of AgNCs and the deposition time conditions of the AgNCs thin film in this example.

AgNCs concentration AgNCs thin film deposition time Example 1 200 mg/mL 30 sec Example 2 1 min Example 3 3 min Example 4 5 min Example 5 100 mg/mL 30 sec Example 6 1 min Example 7 3 min Example 8 5 min Example 9 50 mg/mL 30 sec Example 10 1 min Example 11 3 min Example 12 5 min

comparative example. Preparation of AgNCs thin films

The AgNCs synthesized in Preparation Example 1 were spin-coated on the substrate prepared in Preparation Example 2 at a speed of 1000 rpm for 30 seconds (s) under the concentration conditions shown in Table 1 below to prepare an AgNCs thin film. do.

Measurement Example 1. EDX and XRD analysis

An EDX (Energy Dispersive X-ray spectroscopy) analysis of the surface of the AgNCs thin film according to the Na2Se deposition time of the AgNCs thin film according to the embodiment is shown in FIG. 2(a), and X-ray diffraction according to the deposition time ) The analysis results are shown in FIG. 2 (b).

Referring to (a) of FIG. 2 , it can be seen that the content of Se compared to Ag gradually increases as the loading time (0s: Comparative Example, 30s: Example 1, 180s: Example 3) elapses. In addition, referring to (b) of FIG. 2 , it can be confirmed that the crystal plane 111 of the silver (Ag) crystal is observed at a diffraction peak of 39.31° in the comparative example (w/o NaSe), and NaSe In the case of Example 1 (w/ Na 2 Se for 30 s) treated for 30 minutes, new diffraction peaks of Ag Se (comparative example (w/o Na ₂ Se), 22.99, 26.84, 31.00, 32.86, 33.58, 34.85, 37.2, 40.21, (002), (111), (102), (120), (121), (013), (122), (113), (023), (211) and (014), the peak of Ag gradually decreases as time elapses in Example 1 (w/ Na ₂ Se for 30s) and Example 3 (w/ Na 2 Se for 180s). It can be seen that the Ag ₂ Se peak gradually increases, confirming that the generation of Ag ₂ Se can be controlled according to the loading time.

Measurement example 2. Morphology analysis

TEM (Transmission electron microscopy) and SEM (Scanning electron microscopy) images were observed for the thin film according to the lapse of the deposition time according to the Comparative Examples, Examples 1 and 3, and FIG. 3 ((a): Comparative Example (0s)) , (b): Example 1 (30s), (c): Example 3 (180s)), the left image in (a), (b) and (c) of FIG. 3 is a TEM image, and the right image is an SEM image.

Referring to (a) of FIG. 3 , it can be confirmed that the average particle diameter of AgNCs is 4.7±0.14 nm. Referring to Fig. 3(b), the bulky organic ligand facilitates ionic movement between the nanocrystals on the surface of AgNCs, and at the same time, short inorganic Se ² ions attach to the nanocrystals, and A level of nanocrystal bonding occurs. Referring to (c) of Figure 3, it is converted into nanocrystals (Ag ₂ Se) having selenium (Se) atoms bonded in a non-specific direction, and ultimately the nanocrystals have a non-uniform size and have an uneven shape.

Referring to the SEM images in Figs. 3 (a) to (c), AgNCs were dispersed on the surface of the substrate before sagging with Na ₂ Se (Fig. 3 (a)), but after treatment with Na ₂ Se, As in b) and (c), as the soaking time elapsed, a uniform and continuous thin film composed of an assembly of uniform nanocrystals, and nanocrystals were randomly mixed to form a non-uniform and nanoporous thin film can confirm.

Measurement example 3. Thin film resistance analysis

The resistance of the Ag ₂ Se thin film according to the concentration of AgNCs according to the above example and the loading time of the AgNCs thin film was measured and summarized in Table 2 below.

AgNCs concentration AgNCs thin film deposition time Ag2Se thin film resistance (Ω) Example 1 200 mg/mL 30 sec 25.00±2.45 Example 2 1 min 22.00±2.16 Example 3 3 min 25.33±1.88 Example 4 5 min 38.33±3.85 Example 5 100 mg/mL 30 sec 111.00±11.14 Example 6 1 min 144.67±2.30 Example 7 3 min 185.00±7.07 Example 8 5 min 255.33±6.18 Example 9 50 mg/mL 30 sec 466.00±20.99 Example 10 1 min 481.33±17.46 Example 11 3 min 786.00±102.77 Example 12 5 min 999.66±35.12 comparative example 200 mg/mL 0 min 10 ¹²
(AgNCs thin film)

Referring to Table 2, it can be seen that the thin film continuously increases as the deposition time elapses, and as Ag is converted into Ag ₂ Se, it can be confirmed that the mobility of the charge decreases.

Measurement example 4． Gauge factor analysis according to the holding time

For the thin films according to Examples 1 to 4, the gauge factors according to the loading time at a strain of 4% are summarized in Table 3 below.

AgNCs thin film deposition time Gauge Factor(GF) Example 1 30 sec 5.50±2.92 Example 2 1 min 10.95±7.07 Example 3 3 min 161.26±31.31 Example 4 5 min 11.50±4.44

Referring to Table 3, it can be seen that, when supported for 3 minutes (Example 3), the gauge coefficient exhibited a very high value, with an average value of 161.26. This is because the charge transfer is greatly changed according to the deformation of the thin film in which the conductive nanoparticles (Ag) and the semiconductor particles (Se) are mixed due to the disturbance of the charge flow. The thin film according to Example 3 of the present invention has much superior strain sensitivity than the conventional silver nanocrystal thin film, thereby confirming its applicability to a strain sensor.

Measurement example 5. Application to temperature sensor

The resistance change according to the temperature change from 100 K to 300 K for the thin film according to Example 3 is shown in FIG. The relative resistance change is shown.

Referring to (a) of Figure 4, it can be confirmed that the resistance increases linearly as the temperature increases, and referring to Figure 4 (b), it shows a stable relative resistance change value even with repeated temperature changes. can confirm. Through this, the applicability of the temperature sensor can be confirmed.

On the other hand, the embodiments of the present invention disclosed in the present specification and drawings are merely presented as specific examples to aid understanding, and are not intended to limit the scope of the present invention. It will be apparent to those of ordinary skill in the art to which the present invention pertains that other modifications based on the technical spirit of the present invention can be implemented in addition to the embodiments disclosed herein.

Claims (17)

substrate and;
A thin film for a sensor comprising a silver (Ag) nanocrystal-based chacogenide compound formed on the substrate.
The method of claim 1,
The substrate is a thin film for a sensor, characterized in that it is a flexible substrate.
3. The method of claim 2,
The substrate is a thin film for a sensor, characterized in that PET (polyethylene terephthalate), PI (polyimide), or PDMS (polydimethyl siloxane).
The method of claim 1,
The thin film for a sensor, characterized in that the particle diameter of the silver nanocrystals is 3 to 15 nm.
The method of claim 1,
The chalcogenide compound is a thin film for a sensor, characterized in that Ag ₂ E (E = Se or S).
6. The method of claim 5,
The chalcogenide compound is a thin film for a sensor, characterized in that Ag ₂ Se.
A strain sensor comprising the thin film for the sensor according to claim 1 .
A temperature sensor comprising the thin film for a sensor according to claim 1 .
preparing a silver (Ag) nanocrystal solution;
providing a silver nanocrystal thin film by coating the silver (Ag) nanocrystal solution on a substrate; and
Method for producing a thin film for a sensor comprising the step of supporting the silver nanocrystal thin film in a chalcogen precursor solution.
10. The method of claim 9,
The silver (Ag) nanocrystal solution is a method of manufacturing a thin film for a sensor, characterized in that silver nanocrystals are dispersed in a non-polar solvent.
10. The method of claim 9,
The method for producing a thin film for a sensor, characterized in that the silver (Ag) nanocrystals have a particle diameter of 3 to 15 nm.
10. The method of claim 9,
The method for producing a thin film for a sensor, characterized in that the concentration of the silver (Ag) nanocrystal solution is 50 to 200 mg / mL.
10. The method of claim 9,
The silver (Ag) nanocrystal thin film is a method of manufacturing a sensor thin film, characterized in that formed by spin coating the silver nanocrystal solution on the substrate.
10. The method of claim 9,
The method of manufacturing a thin film for a sensor, characterized in that the substrate is a flexible substrate.
15. The method of claim 14,
The method for manufacturing a thin film for a sensor, wherein the substrate is polyethylene terephthalate (PET), polyimide (PI), or polydimethyl siloxane (PDMS).
10. The method of claim 9,
The chalcogen element of the chalcogen precursor is a method of manufacturing a thin film for a sensor, characterized in that selenium (Se) or sulfur (S).
10. The method of claim 9,
The method for producing a thin film for a sensor, characterized in that the loading time of the silver nanocrystal thin film is 30 seconds (s) to 3 minutes (min).

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