WO2015072628A1

WO2015072628A1 - Nanoplasmonic sensor and measurement method using same

Info

Publication number: WO2015072628A1
Application number: PCT/KR2014/002051
Authority: WO
Inventors: 위정섭; 이태걸
Original assignee: 한국표준과학연구원
Priority date: 2013-11-18
Filing date: 2014-03-12
Publication date: 2015-05-21
Also published as: KR101686011B1; KR20150056997A

Abstract

A nanoplasmonic sensor of the present invention comprises a metal nanostructure having a recessed housing part in which a subject being analyzed is housed, and a measurement part for measuring plasmon resonance in the metal nanostructure. In addition, a measurement method using the nanoplasmonic sensor of the present invention comprises the steps of: preparing the metal nanostructure comprising the recessed housing part in which the subject being analyzed is housed; positioning the subject being analyzed in the housing part; and measuring plasmon resonance in the metal nanostructure.

Description

Nano plasmonic sensor and measuring method using the same

The present invention relates to a nano plasmonic sensor and a measuring method using the same, and more particularly, to a nano plasmonic sensor using a three-dimensional metal nanostructure and a measuring method using the same.

Plasmon resonance is a phenomenon caused by the behavior of free electrons in a metal. When light enters between a metal surface and a dielectric, the free electrons on the metal surface vibrate collectively due to resonance with the electromagnetic field of specific energy. It is a phenomenon. In particular, using optical phenomena caused by plasmon resonance in metal nanostructures made of noble metals such as gold (Au) and silver (Ag), devices have been extensively studied like real-time chemical / biological sensors.

If the photon frequency irradiated to the metal nanostructures resonates with the collective vibration of free electrons in the metal nanostructures, the metal nanostructures exhibit optical properties such as a strong absorption spectrum that did not exist in the bulk state. Accordingly, the electromagnetic field in the local region increases, which phenomenon is generally referred to as Local Surface Plasmon Resonance (LSPR).

One of the technical problems to be achieved by the technical idea of the present invention is to provide a highly sensitive nano plasmonic sensor and a measuring method using the same using a three-dimensional metal nanostructure.

Nanoplasmic sensor according to an embodiment of the present invention, the metal nanostructure having a recessed accommodating portion for receiving the analyte; And it may include a measuring unit for measuring the plasmon resonance phenomenon in the metal nanostructure.

In some embodiments of the present invention, the metal nanostructure may include a top surface and sidewalls protruding from the top surface to define the receiving portion.

In some embodiments of the present invention, the side wall may be arranged to surround the receiving portion at the edge of the upper surface.

In some embodiments of the present invention, the metal nanostructures may have a petri-dish shape.

In some embodiments of the present invention, the surface of the receiving portion may further include a surface coating film including a functional group for adsorbing the analyte.

In some embodiments of the present invention, the metal nanostructure may include at least one of gold (Au), silver (Ag), aluminum (Al), copper (Cu).

In some embodiments of the present invention, the substrate may further include a substrate disposed under the metal nanostructure, and the plurality of metal nanostructures may be arranged on the substrate.

In some embodiments of the present invention, the measurement unit may detect light at or around the surface of the metal nanostructure.

In some embodiments of the present disclosure, the measurement unit may measure a change in absorption, scattering, or extinction characteristics according to the presence or absence of the analyte.

According to one or more exemplary embodiments, a measuring method using a nano plasmonic sensor may include preparing a metal nanostructure including a recessed accommodating part in which an analyte is accommodated; Positioning the analyte in the receptacle; And measuring a plasmon resonance phenomenon in the metal nanostructure.

In some embodiments of the present invention, the receptacle may surround at least a portion and a lower surface of the side of the analyte.

In some embodiments of the present invention, at least half of the volume of the analyte may be contained within the receptacle.

By improving the acceptability of the analyte using a three-dimensional metal nanostructure, a highly sensitive nano plasmonic sensor and a measuring method using the same can be provided.

Various and advantageous advantages and effects of the present invention is not limited to the above description, it will be more readily understood in the course of describing specific embodiments of the present invention.

1 is a block diagram showing a nano plasmonic sensor according to an embodiment of the present invention.

2 is a schematic perspective view illustrating a metal nanostructure according to an embodiment of the present invention.

3A to 3C are diagrams for describing an operating principle of a nano plasmonic sensor including a metal nanostructure according to an embodiment of the present invention.

4 is a graph illustrating an operation principle of a nano plasmonic sensor including a metal nanostructure according to an embodiment of the present invention.

5 is a flowchart illustrating a measurement method using a nano plasmonic sensor including a metal nanostructure according to an embodiment of the present invention.

6A through 6E are diagrams illustrating main steps of a method of forming metal nanostructures according to an exemplary embodiment of the present invention.

7 is electron micrographs showing metal nanostructures in accordance with one embodiment of the present invention.

8A and 8B are electron micrographs showing metal nanostructures according to an embodiment of the present invention.

9 is a graph showing measurement results using the nanoplasmonic sensor of the present invention.

10A to 10C are graphs for explaining simulation results using the nanoplasmonic sensor of the present invention.

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

Embodiments of the present invention may be modified in various other forms, or various embodiments may be combined, and the scope of the present invention is not limited to the embodiments described below. In addition, the embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art. Accordingly, the shape and size of elements in the drawings may be exaggerated for clarity, and the elements denoted by the same reference numerals in the drawings are the same elements.

Referring to FIG. 1, the nano plasmonic sensor 100 according to an embodiment of the present invention includes at least one metal nanostructure 10 and a measuring unit 20. The nano plasmonic sensor 100 may be used for the detection, measurement, and analysis of biomolecules such as bioenzymes, cells, and proteins using plasmon resonance.

The metal nanostructure 10 accommodates an analyte, and the shape of the electromagnetic field may be changed by plasmon resonance at the surface by the analyte. The analyte may include, for example, metal ions or biomolecules such as DNA, proteins, and the like. The nano plasmonic sensor 100 may include a plurality of metal nanostructures 10 according to an embodiment. The metal nanostructure 10 will be described in more detail with reference to FIG. 2 below.

The measuring unit 20 measures a plasmon resonance phenomenon in the metal nanostructure 10 and, for example, a UV-Vis spectrometer for measuring scattering, absorption or extinction characteristics. ) May be included. The measurement unit 20 may measure the change of the analyte such as the presence or absence of the analyte and the chemical reaction accommodated in the metal nanostructure 10 by the change of the resonant frequency. The measurement method using the nano plasmonic sensor 100 will be described in more detail with reference to FIGS. 3A to 5 below.

According to an embodiment, the nano plasmonic sensor 100 may further include a separate monitoring unit such as an optical microscope to observe the change of the analyte in the metal nanostructure 10.

Referring to FIG. 2, the metal nanostructure 110 according to the exemplary embodiment of the present invention may have a receiving portion R recessed inwardly in which the analyte is accommodated. The metal nanostructure 110 may have an upper surface 110F and a lower surface 110B, and sidewalls 110W defining the receiving portion R may be disposed on the upper surface 110F. The side wall 110W may protrude from an edge of the upper surface 110F, and may be disposed to form a side surface of the metal nanostructure 110 along the circumference of the upper surface 110F. The sidewall 110W may be integrally formed with the remaining portions of the upper surface 110F and the lower surface 110B of the metal nanostructure 110. The inclination between the side wall 110W and the upper surface 110F is not limited to the illustrated one and may vary depending on the embodiment.

The metal nanostructure 110 may have a petri-dish shape, and may have a circular or elliptical cross section on a plane. However, the shape of the metal nanostructure 110 of the present invention is not limited thereto, and may include various structures in which the accommodation part R is formed on one surface thereof.

The metal nanostructure 110 may have a length D1 at its long axis in the range of several tens to several hundred nanometers. For example, the length D1 of the metal nanostructure 110 may have a range of 10 nm to 200 nm. The height D2 of the metal nanostructure 110 may range from several to several hundred nanometers, which may be less than the length D1. The side wall 110W may have a predetermined thickness D3, and the receiving portion R may have a predetermined depth D4 greater than the thickness D3. The length D1 of the metal nanostructure 110, the height D2, the thickness D3 of the sidewall 110W, and the depth D4 of the receiving portion R may be determined in consideration of the size of the analyte. For example, the depth D4 of the receiver R may be determined to accommodate at least half of the height or volume of the analyte.

The metal nanostructure 110 may include at least one of gold (Au), silver (Ag), copper (Cu), and aluminum (Al), and may be made of an alloy thereof. Depending on the material of the analyte, the metal nanostructure 110 may further include a surface coating film coated on the surface of the receiving portion R and including a functional group for adsorbing the analyte.

The metal nanostructure 110 of the present embodiment may have a three-dimensional structure including a receiving portion R for accommodating an analyte, and the analyte is accommodated in the receiving portion R, whereby the metal nanostructure 110 is included. It may be in contact with the top surface 110F and sidewalls 110W of the. As a result, the contact area between the metal nanostructure 110 and the analyte may be increased.

Referring to FIG. 3A, the nanoplasmonic sensor of the present invention detects a change in the case where the analyte 120 is positioned in the metal nanostructure 110 after there is no analyte around the metal nanostructure 110. can do. This change affects the plasmon resonance, which can change the resonant frequency. This change in resonant frequency can be shown in (a) and (b) graphs, respectively, in the graph of FIG. Therefore, as shown in FIG. 4, a change in optical characteristics, for example, a spectrum including a peak wavelength in the scattering spectrum, may be detected as a phenomenon in which the direction of the arrow is shifted.

The surface plasmon resonance generated by the free electrons in the metal of the metal nanostructure 110 may be analyzed by the metal nanostructure 110 when the analyte 120, such as particles or molecules, is placed around the surface of the metal nanostructure 110. The resonance frequency can be changed in this manner.

Referring to FIG. 3B, in the nano plasmonic sensor of the present invention, when an analyte 120a of the first form exists around the metal nanostructure 110, and changes to the analyte 120 of the second form, This change can be detected. The change may include both chemical and physical changes of the

analyte

120a and 120, and may be, for example, a change in the activity of the

analyte

120a or 120.

Referring to FIG. 3C, the nanoplasmonic sensor of the present invention changes the case where the analyte 120b is positioned around the metal nanostructure 110 after there is no analyte around the metal nanostructure 110. It can be detected. In this case, the analyte 120b may be adsorbed on the outer surface as well as the inside of the metal nanostructure 110. The nano plasmonic sensor of the present exemplary embodiment can detect not only the case where the analyte 120b is located in the receiving portion R (see FIG. 2) of the metal nanostructure 110 but also the change when the analyte 120b is located on the outer surface. have.

3B and 3C, as described above with reference to FIG. 4, the resonance frequency of the plasmon resonance is changed, and thus, the scattering spectrum may be shifted.

Referring to FIG. 5, first, a step (S210) of preparing a metal nanostructure having a receiving portion may be performed. The metal nanostructure may be the metal nanostructure 110 described above with reference to FIG. 2. In particular, the metal nanostructures may be provided in a plurality of arrangement. Depending on the characteristics of the analyte, forming a surface coating film including a functional group for adsorbing the analyte on the surface of the receiver may be added.

Next, the step (S220) of measuring the optical properties of the metal nanostructure to obtain a first result may be performed. The optical characteristic may be the same as the scattering spectrum described above with reference to FIG. 4, but the present invention is not limited thereto, and all of the characteristics capable of identifying the plasmon phenomenon may be included.

Next, placing the analyte on the metal nanostructure (S230) may be performed. As described above with reference to FIGS. 3A to 3C, the analyte may be located at an accommodating portion in the metal nanostructure or adsorbed onto the surface of the metal nanostructure. The analyte can be delivered to the metal nanostructures, for example, by spin coating, screen printing, spraying, or the like in solution.

Next, an operation (S240) of obtaining a second result may be performed by measuring optical characteristics of the metal nanostructure containing the analyte. This is to measure the change of the resonance frequency due to the plasmon phenomenon.

Next, comparing the first and second results, or comparing the second result with the previous result (S250) may be performed. When comparing the first and second results, as described above with reference to FIGS. 3A and 3C, it is possible to recognize a difference depending on the presence or absence of an analyte. Thus, detection of the analyte may be possible. When comparing the second result with the previous second result, as described above with reference to FIG. 3B, it is possible to detect a change in the analyte. Optionally, after the step (S240) and the step (S250) of continuously obtaining the second result in a predetermined time unit may be continuously performed, the change of the analyte may be analyzed in real time.

Referring to FIG. 6A, first and second mask layers 130 and 140 may be sequentially formed on the substrate 101.

The substrate 101 is a layer on which a metal nanostructure 110 (refer to FIG. 2) is formed, and may correspond to a substrate forming a part of a nano plasmonic sensor. The substrate 101 may be selected from a conventional semiconductor substrate such as a silicon substrate, a conductive substrate, or an insulating substrate. In addition, the substrate 101 may be a light transmissive substrate, and may transmit a specific light source.

The first and second mask layers 130 and 140 may be made of a thermosetting, thermoplastic and / or photocurable material, and may be a polymer resin layer. The first and second mask layers 130 and 140 may be made of different materials, for example, a photoresist material such as polymethyl methacrylate (PMMA). The first and second mask layers 130 and 140 may be sequentially applied onto the substrate 101 by spin coating, screen printing, spraying, or the like. The thicknesses of the first and second mask layers 130 and 140 may vary depending on the size of the metal nanostructure 110 to be formed.

Referring to FIG. 6B, the second mask layer 140 may be patterned to form a second mask pattern 140P.

The second mask pattern 140P may be formed by forming a separate mask layer and removing a portion of the second mask layer 140 by etching. In some embodiments, the second mask layer 140 may be formed using a nanoimprint process. In this case, the second mask layer 140 and the first mask layer 130 are simultaneously patterned by the imprint mold, so that a part of the first mask layer 130 may also be removed in this step.

Referring to FIG. 6C, the first mask layer 130 may be selectively etched to form the first mask pattern 130P.

An etching process may be performed in the region of the first mask layer 130 exposed by the second mask pattern 140P. The etching process may be a dry etching process such as, for example, wet etching or reactive ion etching (RIE), and anisotropic etching may be performed. As a result, the first mask pattern 130P may be formed, and an undercut may be formed by removing the lower first mask layer 130 from the edge region of the second mask pattern 140P.

In this step, the etching process may be performed under a condition having a large selectivity with respect to the first mask layer 130. Thus, for example, when wet etching is used, an etchant having a relatively high selectivity with respect to the first mask layer 130 may be used.

Referring to FIG. 6D, the nanostructure 110 may be formed by forming the metal layer 110M on the substrate 101.

The metal nanostructure 110 may be formed on a portion of sidewalls of the exposed substrate 101 and the first mask pattern 130P using the first and

second mask patterns

130P and 140P as masks. The metal nanostructure 110 is disposed by placing the substrate 101 and the deposition material source to have a predetermined inclination between the substrate 101 and the source of the deposition material, and rotating the substrate 101 or the source of the deposition material, thereby depositing the deposition material. The substrate 101 may be formed by being moved at a predetermined angle with respect to the substrate 101.

In this case, the shape of the metal nanostructure 110 to be formed may vary according to the angle of inclination. Thus, in this embodiment, in order to have a flat top surface 110F (see FIG. 2), the path through which the deposition material is moved onto the substrate 101, indicated by the dotted line, is formed so that the metal nanostructure 110 is formed. It can be adjusted so that it is not excessively overlapped or spaced at the center of the region. In addition, the thickness of the first mask pattern 130P may be adjusted to be deposited on the side of the first mask pattern 130P, and by adjusting the height, the depth of the receiving portion R (see FIG. 2) of the metal nanostructure 110 is increased. Can be adjusted.

The metal nanostructure 110 may be formed using, for example, physical vapor deposition (PVD), such as thermal evaporation, electron beam evaporation, or sputtering. have.

Referring to FIG. 6E, a process of removing the first and

second mask patterns

130P and 140P may be performed.

As a result, only the metal nanostructure 110 may be arranged on the substrate 101. The metal nanostructures 110 may be arranged in rows and columns or may be arranged in an orderly manner, and the number of the metal nanostructures 110 may vary depending on embodiments.

Referring to FIG. 7, a result of analyzing a metal nanostructure 110 formed of gold (Au) formed on a silicon (Si) substrate by a scanning electron microscope (SEM) is shown. Is shown with a high magnification.

The metal nanostructure 110 has a path in which the deposition material moves onto the substrate 101 substantially in the center of the metal nanostructure 110, as shown in FIG. 6D in the process described above with reference to FIG. 6D. It was formed to be controlled so as not to overlap. Therefore, the metal nanostructure 110 of the shape as shown in FIG. 2 could be formed.

The size of the metal nanostructure 110 is about 200 nm or less, and may be selected according to the desired analyte. In addition, the plurality of metal nanostructures 110 may be arranged in rows and columns.

8A and 8B, results of analyzing gold (Au) metal nanostructures 110 ′ and 110 ″ formed on a silicon (Si) substrate by a scanning electron microscope (SEM) are shown.

In the case of FIG. 8A, in the process described above with reference to FIG. 6D, a path through which the deposition material moves onto the substrate 101 is overlapped by a first length at the center of the metal nanostructure 110 ′ ( 110 ') is shown. In FIG. 8B, the metal nanostructure 110 ″ formed by overlapping a path through which the deposition material moves on the substrate 101 by a second length smaller than the first length at the center of the metal nanostructure 110 ″. ) Is shown. Projections are formed in regions where the paths of deposition material are moved onto the substrate 101 overlap, and the projections appear as bright images on electron micrographs.

As such, depending on the formation method, the shape of the metal nanostructures 110 ′ and 110 ″ may be controlled. The shape of the various metal nanostructures 110 ′, 110 ″ may be appropriately selected depending on the desired analyte.

Referring to FIG. 9, graphs represented by three kinds of lines are shown, and (a) corresponds to an absorption spectrum before analyte is adsorbed or received on a metal nanostructure. (b) shows the absorption spectrum when the rhodamine B-isothiocyanate (RhB) molecule is adsorbed to the metal nanostructure. The RhB molecule has a sulfur atom at its end, whereby it can be chemisorbed to metal nanostructures made of gold (Au). (c) shows an absorption spectrum when latex beads having a size of about 40 nm are accommodated in the metal nanostructure.

Analyzing the three graphs, the absorption spectrum of the metal nanostructure was shifted by 15 nm longer than the graph when the RhB molecules were adsorbed, and the absorption spectrum of the metal nanostructure was about 35 nm when the latex beads were accommodated. Moved to long wavelength. Through this change in the absorption spectrum, it is possible to detect changes in specific molecules or materials around the metal nanostructures. In addition, it can be seen that the change in the absorption spectrum is different according to the analyte, it will be possible to use the nano plasmonic sensor as desired by using this.

10a to 10c illustrate the degree of scattering cross section spectra with increasing contact area between the metal nanostructure and the analyte, and before the analyte is accommodated using three types of metal nanostructures. The graph and the graph after the analyte was accommodated are shown as (a) and (b), respectively. As analyte, spherical latex beads having a refractive index of about 1.4 and a diameter of about 100 nm were used.

Referring to FIG. 10A, latex beads may be applied to a disk-shaped two-dimensional metal nanostructure having a diameter of about 150 nm without a receiving portion R (see FIG. 2), that is, without a sidewall 110W (see FIG. 2). The shift of the spectrum when accepted is shown, showing a shift of less than 1 nm.

Referring to FIG. 10B, latex beads may be formed in the metal nanostructures according to the exemplary embodiment of the present invention, having a size of about 150 nm and having a first height of about 60 nm having a relatively low height of the sidewall 110W. The shift in the spectrum when accepted is shown, showing a shift of about 10 nm.

Referring to FIG. 10C, when the height of the sidewall 110W has a second height of about 90 nm, the height of the sidewall 110W is greater than the first height of FIG. 10B. The shift in the spectrum when the latex beads were accommodated in the metal nanostructure was shown, showing a shift of about 35 nm.

According to this, the nano plasmonic sensor using the three-dimensional metal nanostructure according to an embodiment of the present invention has a higher sensitivity than the case of using the two-dimensional metal nanostructure, it is possible to detect and analyze even when the amount of analyte is relatively small. It can be seen. In addition, it can be seen that the sensing sensitivity can be further improved by adjusting the height of the sidewall of the metal nanostructure according to the analyte.

It is intended that the invention not be limited by the foregoing embodiments and the accompanying drawings, but rather by the claims appended hereto. Accordingly, various forms of substitution, modification, and alteration may be made by those skilled in the art without departing from the technical spirit of the present invention described in the claims, which are also within the scope of the present invention. something to do.

Nano plasmonic sensor according to an embodiment of the present invention can be used for the detection, measurement and analysis of biomolecules such as biological enzymes, cells and proteins using plasmon resonance phenomena.

Claims

Metal nanostructures having recessed receptacles in which the analyte is received; And

Nano plasmonic sensor comprising a measuring unit for measuring the plasmon resonance phenomenon in the metal nanostructure.
According to claim 1,

The metal nanostructure includes a top surface and a sidewall protruding from the top surface to define the receiving portion.
The method of claim 2,

The sidewalls are arranged to surround the receiving portion at the edge of the upper surface nano plasmonic sensor.
According to claim 1,

The metal nanostructure is a nano-plasmonic sensor, characterized in that the petri dish (petri-dish) shape.
According to claim 1,

The nano-plasmonic sensor is coated on the surface of the receiving portion, further comprising a surface coating film containing a functional group for adsorbing the analyte.
According to claim 1,

The metal nanostructures are at least one of gold (Au), silver (Ag), aluminum (Al), copper (Cu) nano plasmonic sensor.
According to claim 1,

Further comprising a substrate disposed under the metal nanostructure,

The nano plasmonic sensor is characterized in that the plurality of metal nanostructures are arranged on the substrate.
According to claim 1,

The measuring unit nanoplasmonic sensor, characterized in that for detecting the light on the surface or the periphery of the metal nanostructure.
The method of claim 8,

The measurement unit nanoplasmonic sensor, characterized in that for measuring the change in absorption (absorption), scattering (scattering), or extinction characteristics according to the presence or absence of the analyte.
Providing a metal nanostructure comprising a recessed receiving portion in which the analyte is received;

Positioning the analyte in the receptacle; And

Measuring method using a nano plasmonic sensor comprising the step of measuring the plasmon resonance phenomenon in the metal nanostructure.
The method of claim 10,

The receiving portion measuring method using a nano plasmonic sensor, characterized in that to surround at least a portion and a lower surface of the side of the analyte.
The method of claim 11, wherein

At least half of the volume of the analyte is accommodated in the receiving portion.