KR20070080914A - Apparatus of localized surface plasmon sensor using ordered nano-sized metal structures and method manufacturing the same - Google Patents

Abstract

A localized surface plasmon sensor using ordered nano-sized metal structures is provided to induce a localized surface plasmon resonance phenomenon by installing a metal thin film and a T-type metal structure on a top of a substrate. A localized surface plasmon sensor using ordered nano-sized metal structures includes a prism(2), a substrate(4), a metal thin film(8), T-type metal structures(10,10'), a light source, and a light-receiving unit. The substrate is installed on a top of the prism. The metal thin film is installed on a top of the substrate. More than one T-type metal structure is installed on a top of the metal thin film. The light source is installed to be separated at constant intervals on one side of a bottom of the substrate to radiate an input light inputting to the metal thin film due to passing the substrate. The light-receiving unit is installed to be separated at constant intervals on one side of a bottom of the substrate to detect the light changed by a localized surface plasmon resonance phenomenon of the input light.

Description

Apparatus of Localized Surface Plasmon Sensor Using Ordered Nano-Sized Metal Structures and Method Manufacturing the Same

1 is a cross-sectional view schematically showing a conventional surface plasmon resonance sensor,

Figure 2 is a graph showing the surface plasmon resonance curve for the presence or absence of sample mounting of the conventional surface plasmon sensor,

3 is a cross-sectional view showing a local surface plasmon sensor according to the present invention;

4 is a graph conceptually illustrating the minimum reflectance at a curved angle range and a resonance condition in a reflectance curve of a local surface plasmon sensor according to the present invention;

5 is a graph showing the sensitivity distribution according to the GF value of the local surface plasmon sensor according to the present invention,

6 is a graph showing a periodic distribution of a T-shaped metal structure for improving sensitivity of a local surface plasmon sensor according to the present invention;

7 is a graph showing the change in SPR CAW according to GF in the topical surface plasmon sensor according to the present invention,

8 is a graph showing a change in MRR according to GF in the local surface plasmon sensor according to the present invention.

<Description of the symbols for the main parts of the drawings>

2, 102: prism 4, 104: substrate

6, 106: binding metal 8, 108: metal thin film

10, 10 ': T-shaped metal structure 12, 112: sample

14, 114: light source 16, 116: light receiving unit

The present invention relates to a sensor using a surface plasmon resonance phenomenon, and more particularly, using a localized surface plasmon resonance, the change in the thickness of the sample, the refractive index and / or the reaction of a biochemical or biological material It relates to a local surface plasmon sensor comprising a T-shaped metal structure for measuring the degree.

The principle of surface plasmon resonance is known as surface electromagnetic waves that quantize the collective vibrations of electrons occurring on the metal thin film surface along the interface between metal and adjacent dielectric material.

The phenomenon of surface plasmon excitation is called Surface Plasmon Resonance (SPR). Here, various methods are known to excite the surface plasmon, but in order to generate the surface plasmon, a metal thin film is laminated on two medium interfaces having different refractive indices so that total reflection can occur. It is possible to construct a Kretschmann structure.

1 shows a general structure of a SPR sensor, a so-called Kretschman type SPR sensor.

As shown in FIG. 1, the SPR sensor basically consists of a substrate 104, a prism 102, a binding metal 106, and a metal thin film 108 that produces an SPR. The prism 102 is typically a semi-circular or triangular prism made of a transparent glass such as BK7 or SF10, the metal thin film 108 is typically 40 to 50nm thick, the material is gold or silver. At this time, the sample 112 to be measured the refractive index change in the SPR sensor is provided on the top of the metal thin film (108).

The SPR sensor includes a fixed light source 114 for emitting incident light toward the metal thin film 108 and a light receiving unit 116 for measuring the intensity of reflected light reflected from the surface of the metal thin film 108. Here, the light source 114 is a laser of a single color light, a light emitting diode or a white light of a multi-wavelength band is used.

When the wave vector of the position parallel to the surface of the metal thin film 108 and the wave vector of the surface plasmon coincide with the incident light, the surface plasmon resonance phenomenon occurs. Therefore, the refractive index of the prism 102 is n and the resonance angle is _When the dielectric constants of _re , the metal thin film 108 and the sample 112 are ε ₁ and ε ₂ , respectively, Equation 1 is established.

[Equation 1]

Therefore, when the resonance angle θ _re is known, it is possible to calculate the dielectric constant ε ₂ of the sample 112 from Equation 1, from which the refractive index of the sample 112 or the change in the refractive index from the reference sample can be known. This change in refractive index enables the quantitative and qualitative analysis of the thickness of the thin film sample or the adsorbed sample.

The most commonly used incident angle resolution type SPR device has been dozens of years since the first publication of SPR excitation by optical methods by E.Kretschmann, Z. Phys. 241, 313, 1971. It has evolved over the years with various structures and applications.

In particular, due to the excellent characteristics of the SPR, as the SPR device has been commercialized, much research has been conducted on the intrinsic performance and limitations of the SPR device. According to these studies, the performance of an SPR device is usually expressed by dynamic measurement range, sensitivity, or resolution. The units can be expressed based on the refractive index of the liquid sample.

을 나타내고, 기기의 분해능은 SPR 측정기기가 계측하여 결정할 수 있는 최소 물리량 즉, 측정 가능 한 최소 굴절률을 나타낸다. 이때, 액체시료의 굴절률이 SPR의 성능평가의 기준시료가 되는 것은 SPR이 많이 활용되고 있는바, SPR 센서 분야의 주요 시료가 일반적으로 액체상태이기 때문이다. 즉, 금속박막위에 형성된 감지막이 액체상에 용해된 계측시료인 단백질 또는 이온과 같은 생화학물질과 반응한 결과 나타나는 공명각의 변화의 기준점은 대부분 액체시료자체의 공명각 근처에서 일어나기 때문이다. 그러므로 액체시료의 굴절률은 SPR 측정에 있어서 기기설계의 기준점이며 성능평가의 주요 시료가 된다.Here, the dynamic measurement range of the instrument means a range of measurable refractive index, and the sensitivity is the derivative of the measured physical quantity (angle) with respect to the change in the refractive index.

The resolution of the device represents the minimum physical quantity that can be measured and determined by the SPR measuring device, that is, the minimum measurable refractive index. In this case, the refractive index of the liquid sample becomes a reference sample for the performance evaluation of the SPR because the SPR is widely used because the main sample in the SPR sensor field is generally in a liquid state. That is, the reference point of the change of the resonance angle resulting from the reaction of the sensing film formed on the metal thin film with a biochemical such as a protein or ion which is a measurement sample dissolved in the liquid phase occurs mostly near the resonance angle of the liquid sample itself. Therefore, the refractive index of the liquid sample is the reference point of the instrument design in SPR measurement and is the main sample for performance evaluation.

These three indicators are performance indices that provide important performance criteria for determining and improving the performance of SPR devices. When these three performance indicators are examined in terms of the structural and principle of the device, the three performance indicators are correlated with each other, so that maintaining the best performance indicators has many limitations. It is directly related to the part performance and manufacturing technology used in the equipment, and the problem of limiting the dynamic measurement range in order to maximize the resolution occurs. This problem mainly occurs in a method using a multichannel photodetector.

When detecting wedge-shaped light at an angle through an n-channel photodetector, the resolution is determined by the number of channels and the distance between the SPR sensing unit and the detector in the prism. Therefore, the first step to increase the resolution is to increase the number of channels, which is limited by the number of channels per unit area due to the limitations of current photodetector fabrication techniques.

Next, the effect of increasing the distance of the wedge-shaped light for a given optimal number of channels or using the lens system as an optical method can increase the resolution, but this method also increases the structural aspect of the instrument or the intrinsic nature of the optics. Limitations There are limits to technological improvements. Of course, the research on the structure of the device with optimized performance using these methods has been published and commercialized previously, and other researches that have improved the performance by adding various signal processing techniques have been published. However, as suggested earlier, this set of measures to improve the resolution results in maintaining or decreasing the figure of merit rather than in terms of improving the dynamic range. In the case of wedge fluorescence, the dynamic measurement range is determined by the spreading angle of the light, but when the angle is widened to increase the dynamic measurement range, it is limited by the size and distance of the optical detection device. This is a problem that must be compromised.

In addition, the sensitivity of the SPR device is greatly affected by various physical quantities associated with the SPR phenomenon, which is influenced by the wavelength of light used or the characteristics of the metal, that is, the type of metal thin film, the refractive index, or the refractive index of the prism used. Moreover, the refractive index of the prism affects the dynamic measuring range as well as the sensitivity of the device. As the refractive index of the prism increases, the dynamic measuring range increases under a given condition.

In addition, the sensitivity of the SPR device is closely related to the resolution of the SPR device. Referring to the definition of the sensitivity of the SPR device, it is easy to see that the resolution increases as the sensitivity increases under the same conditions as the range of the refractive index. In other words, the resolution of measured values such as angle and light intensity is fundamentally limited in accuracy, such as the noise of the device itself or the problem of the accuracy of the device manufacturing, but it is necessary to measure when the sensitivity of the device is improved by appropriate methods. The measurement limits of physical quantities are much lower, resulting in better resolution.

Taken together, technical efforts to improve the performance of SPR devices are important for accessing fundamental problems, such as improving the performance of parts and optimizing the design of the structure, but inherent limitations due to the level of manufacturing technology are difficult to overcome. to be. Therefore, in principle, it is necessary to find a way to further improve the performance of the device, and the important performance indicators can be summarized by the dynamic range and sensitivity of the device. However, there are many limitations as described above in order to satisfy these two performance indices simultaneously in the conventional technical level or method. Therefore, the conventional angular resolution SPR system, which is commercially available or reported in the literature, has been researched and developed for the purpose of improving only one of two performance indicators. For example, most commercially available SPR systems are designed to measure the measurement of low refractive index solutions, such as buffers, so that the dynamic range is relatively limited, with a refractive index of 1.33 to 1.40, but resolution is measured in units of refractive index. It is designed to have a precision of about 10 ^-6 degrees. In addition, a case of high refractive index such as various organic solvents using a high refractive index prism has been reported to improve the dynamic measurement range even if the performance is reduced in terms of sensitivity.

As an example of such a prior art, Korean Patent Publication No. 10-2004-0039553 relates to a local surface plasmon sensor using aligned nano-sized metal structures and a method of manufacturing the same. A sample, a transparent substrate, fixed to the sample on the substrate, aligned at regular intervals, having the same shape, having a nanometer size, and inducing localized surface plasmon resonance absorption of the incident light. The present invention discloses a local surface plasmon sensor comprising a plurality of metal structures, and a light receiving unit for detecting light changed by localized surface plasmon resonance absorption of the incident light.

In addition, Korean Patent Publication No. 10-2004-0102847 discloses an optical analysis device for measuring the interaction of biochemicals and biomaterials using surface plasmon resonance, or measuring the thickness and refractive index, which are optical constants of thin films, and the refractive index of a solution. The present invention relates to an SPR measuring apparatus in which a dynamic measurement range of a liquid sample refractive index is widened by adjusting an incident plane angle and an exit plane angle with respect to the bottom of a prism in an SPR device using a prism.

However, the conventional local surface plasmon sensor has a limitation in improving dynamic measurement range and sensitivity affecting the performance of the angular resolution SPR sensor, and has a problem that cannot be applied where a precise and accurate experiment is required.

The present invention has been derived to solve the above problems, can be measured in real time, can improve the measurement sensitivity than conventional sensors, can arbitrarily adjust the surface plasmon resonance absorption conditions, and measure the reflected light There is a technical problem in providing a local surface plasmon sensor and a method of manufacturing the same.

The present invention is a prism; A substrate provided on top of the prism; A metal thin film provided on the substrate; At least one T-shaped metal structure provided on the top of the metal thin film; A light source provided at a lower end side of the substrate to be spaced apart by a predetermined distance to emit incident light passing through the substrate and incident on the metal thin film; It provides a local surface plasmon sensor is provided on the bottom side of the substrate to be spaced apart by a predetermined distance to detect the light changed by the localized surface plasmon resonance absorption phenomenon for the incident light.

When the sample to be measured is provided on the upper surface of the T-shaped metal structure of the local surface plasmon sensor (hereinafter referred to as a "sensor") according to the present invention, the light provided from the light source is incident through the prism at an angle with respect to the substrate, Light totally reflected from inside the prism is incident on the light receiving portion. That is, when the wave vector component parallel to the T-shaped metal structure coincides with the electron density oscillating along the interface of the T-shaped metal structure and the sample located on the upper surface thereof, that is, the energy of incident light is Mostly absorbed by surface plasmons.

At this time, the distribution of the surface plasmon is exponentially reduced in both directions between the interface of the T-shaped metal structure and the measurement sample. Therefore, the resonance absorption condition of the surface plasmon is sensitively changed depending on the thickness, refractive index, or liquid sample of the sample touching the surface of the T-shaped metal structure. By measuring the changed reflectance, a change in refractive index, thickness or concentration of the sample can be quantitatively measured.

The sensor can be manufactured as follows.

The method of manufacturing a sensor according to the present invention comprises the steps of: providing a substrate; Forming a metal thin film having a thickness of several tens of nm by using one of a group of deposition methods including electron beam vacuum deposition, thermal evaporation, or sputtering on top of the substrate; Electron beam lithography, interference lithography, ionbeam lithography, x-ray lithography, diblock copolymer or nanoimprint on top of the metal thin film Any one of a group of patterning methods, including lithography (nano imprint lithography), using the same shape and at regular intervals, and having several to tens of nm in size, localized surface plasmon resonance for any incident light Forming T-shaped metal structures inducing absorption phenomenon; Forming a sample to be measured on top of the T-shaped metal structure; And arranging a light source to provide the incident light to the T-shaped metal structure and a light receiving unit that detects light changed by the localized surface plasmon resonance absorption phenomenon for the incident light.

If necessary, a step of forming a metal binding layer may be included between the step of providing the substrate and the step of forming the metal thin film.

The sensor according to the present invention can measure in real time and / or without markers, can improve measurement sensitivity, can arbitrarily control the surface plasmon resonance absorption conditions more variously, and can adopt more various measurement methods.

Hereinafter, described in detail with reference to the accompanying drawings. However, the following description is only for describing the present invention in detail and does not limit the scope of the present invention by the following description.

Figure 3 is a cross-sectional view showing a local surface plasmon sensor according to the present invention, Figure 4 is a graph conceptually showing the minimum reflectance in the curve angle range and resonance conditions in the reflectivity curve of the local surface plasmon sensor according to the present invention, Figure 5 A graph showing the sensitivity distribution according to the GF value of the local surface plasmon sensor according to the invention, Figure 6 is a graph showing the periodic distribution of the T-shaped metal structure for improving the sensitivity of the local surface plasmon sensor according to the invention, Figure 7 Fig. 8 is a graph showing a change in SPR CAW according to GF in a local surface plasmon sensor according to the present invention, and Fig. 8 is described together with a graph showing a change in MRR according to GF in a local surface plasmon sensor according to the present invention.

As shown in Fig. 3, the topical surface plasmon biosensor according to the present invention comprises a prism 2; A substrate 4 provided on the prism 2; A metal thin film 8 provided on the substrate 4; At least one T-shaped metal structure (10, 10 ') provided on the top of the metal thin film (8); A light source 14 disposed at a lower end side of the substrate 4 so as to be spaced apart from each other by a predetermined distance and emitting incident light passing through the substrate 4 and entering the metal thin film 8; It is formed to include a light receiving portion 16 provided on the lower side of the substrate 4 to be spaced apart by a predetermined interval to detect the light changed by the localized surface plasmon resonance absorption phenomenon for the incident light.

The prism 2 according to the present invention is made of a transparent medium having a high refractive index (nd = 1.5 to 2.0), such as BK7, SF10, SF11, LaSF or N9, and has a triangular, hemispherical, parallelogram, inverted trapezoidal or semi-cylindrical shape. It can be prepared as.

The substrate 4 according to the present invention is provided on the top of the prism 2, and serves to fix and support the nanometer metal thin film 8 and the T-shaped metal structures 10 and 10 '. The substrate 4 may be a transparent dielectric such as a glass substrate such as silica (SiO ₂ ), and a silicon (Si) substrate may be used according to the function and characteristics of the sensor, and titanium oxide (TiO ₂ ) and tantalum oxide. A substrate 4 of a transparent oxide such as (Ta ₂ O ₅ ) or aluminum oxide (Al ₂ O ₅ ) may be used, preferably transparent so that incident light is easy to reach the T-shaped metal structures 10, 10 ′. The board | substrate 4 which has a characteristic is preferable.

Here, the substrate 4 is preferably made of a material having the same refractive index as the dielectric constituting the prism 2.

The metal thin film 8 according to the present invention is provided on the upper surface of the substrate 4 to reflect incident light and generate surface plasma, and includes gold (Au), silver (Ag), platinum (Pt), and palladium ( Pd), copper (Cu), silicon (Si), germanium (Ge), aluminum (Al) or mixtures thereof, which may be electron beam vacuum deposited to a thickness of several tens of nm, preferably 35 to 50 nm, or It deposits through the vacuum deposition method, such as thermal vapor deposition.

If necessary, between the substrate 4 and the metal thin film 8, a binding metal layer 6 for increasing adhesion between the substrate 4 and the metal thin film 8, for example, titanium (Ti) or chromium (Cr) is approximately It may be deposited to a thickness of 1 to 5 nm.

T-shaped metal structure (10, 10 ') according to the present invention is provided on the top of the metal thin film (8) layer to generate a local surface plasmon resonance phenomenon to improve the sensitivity, the cross-section is based on the horizontal axis of the sensor T It is shaped like a child and has a length of several hundred micrometers or more.

The T-shaped metal structures 10 and 10 'have a transverse cutting surface connected to the upper portion of the T-shaped metal structure 10 having a "-" shape and the lower surface of the upper surface of the T-shaped metal structure 10. T-shaped metal structure (10, 10 ') made of a "|" shape, the T-shaped metal structure (10, 10') is a T-shaped metal structure (10, 10) for optical conditions that induce surface plasmon resonance Can be controlled using the structural definition of ').

Here, the structural definition [GF: geomeric factor] of the T-shaped metal structures 10 and 10 'is the ratio of the thickness of the horizontal axis of the upper portion of the T-shaped metal structure 10 to the horizontal thickness of the T-shaped metal structures 10 and 10'. It is represented by the following equation (3).

[Equation 3]

GF = thickness of the top of the T-shaped metal structure / total thickness of the T-shaped metal structure

At this time, the T-shaped metal structure (10, 10 ') is provided with at least one size smaller than the wavelength of the incident light in order to take advantage of the localized surface plasmon effect, arranged at regular intervals on the top of the metal thin film (8), mutually In the same form.

These regularly aligned T-shaped metal structures 10, 10 'are induced to have localized surface plasmons inside or on their surfaces. The T-shaped metal structures 10, 10 'are microscopic in terms of the optical properties of the dielectric, i.e., the sample 12, in contact with the T-shaped metal structures 10, 10' by utilizing the resonance absorption of localized surface plasmons present on the surface. Measure the change.

The T-shaped metal structures 10 and 10 'have a high ratio of absorption (k) to refractive index (k) (Au) and silver (Ag) in terms of optical properties, particularly surface plasmon resonance. ), Platinum (Pt), palladium (Pd), copper (Cu), silicon (Si), germanium (Ge), aluminum (Al) or mixtures thereof, and the like, and preferably In consideration of the affinity of the gold (Au) is preferably formed.

This arrangement of the T-shaped metal structures 10, 10 'is such that the spatially bounded T-shaped metal structures 10, 10' on the substrate 4 induce the use of localized surface plasmon resonance absorption. 1, it is distinguished from a conventional SPR sensor or an SPR imaging system in which a metal thin film 8 is entirely coated on a two-dimensional substrate 4 as shown in FIG. 1.

In addition, the T-shaped metal structures 10 and 10 'are arranged in nanometer sizes so that the metal colloid and the macroscopic deposition conditions are provided on the substrate 4 using a change in macroscopic deposition conditions, for example, deposition rate, thickness, or heating conditions. It is distinguished from nano beads or nano clusters.

Thus, the sensor using the T-shaped metal structure (10, 10 ') and the sensor using an unaligned metal colloid, nanobeads or clusters having a size of nanometers but having an irregular shape and a non-uniform distance Are distinguished.

Such a technique for forming an array of actively aligned nano-sized T-shaped metal structures 10, 10 'on top of the substrate 4 belongs to the technical field of nano lithography.

The array of T-shaped metal structures 10 and 10 'may be formed by physical methods such as electron beam lithography, interference lithography, ion beam lithography, X-ray lithography, and the like, and may be formed by chemical methods using a diblock copolymer. Aligning the T-shaped metal structures (10, 10 ') using the NIL (Nano Imprint Lithography) method, which creates a nanostructure by applying pressure to a polymer such as PMMA and painting a metal structure of a fine structure beforehand An array can be formed on top of the substrate 4.

Here, the optimal nanolithography technique for forming an ordered arrangement of the T-shaped metal structures 10 and 10 'may vary depending on the spatial size and type of the T-shaped metal structures 10 and 10'.

In order to achieve the object of the present invention, the size of the T-shaped metal structures 10 and 10 'is made from several tens to hundreds of nm, and the thickness of the T-shaped metal structures 10 and 10' is made from several tens of nm.

In a particular embodiment, the T-shaped metal structures 10, 10 'according to the present invention preferably have a spacing between the respective T-shaped metal structures 10, 10' greater than the width of the T-shaped metal structures 10, 10 '. Preferably, the distance between the T-shaped metal structures 10 and 10 'is 2 to 5 times larger than the size of the T-shaped metal structures 10 and 10' itself. In view of the resonance absorption in the visible light region, the T-shaped metal structures 10 and 10 'have a width of about 20 to 200 nm and a thickness of 10 to 100 nm, and lattice constants such as metal structures 10 and 10 The spacing between ') is made at about 50-500 nm. In particular, as shown in FIG. 6, the interval of the T-shaped metal structure to obtain the maximum sensitivity improvement characteristic varies depending on the GF, but in general, the interval is between 50 nm and 200 nm in order to expect a sensitivity improvement effect of 20 times or more. It is preferable to become.

Sample 12 according to the present invention is provided on the top of the metal thin film 8, a sample 12 such as serum containing a biological molecule may be used. The sample 12 is an oxide thin film or LB (Langmuir-Boldgett) film for measuring a change in refractive index with a measuring object that is in contact with or fixed to the surface of the metal thin film 8, for example, selectively binds to a specific ligand. Self-embedded monolayers (SAMs), proteins, enzymes or nucleic acids such as nucleic acids, and may be a gas or liquid atmosphere.

When the concentration, thickness, and / or refractive index of the sample 12 is changed, the localized surface plasmon resonance condition is changed accordingly, and thus the contrast of the reflected light reflected by the light receiving unit 16 is changed.

Here, the method of depositing the sample 12 on the metal thin film 8 may use a self assembled monolayer (SAM) or an immobilization technique mainly used to form a monomolecular thin film.

In the self-assembly method, the receptor of the sample 12 to be reacted is dissolved in a solvent and flowed to the top of the metal thin film to form a thin film layer of a single molecule on the metal surface, and then the sample to react on the top of the metal surface. Contact is a reaction between the receptor and the sample by contact. At this time, the change of the refractive index of the metal surface is changed according to the degree of bonding, the resonance condition is changed eventually.

The light source 14 according to the present invention provides incident light, which is a TM or P-polarized monochromatic light source which provides light having a short wavelength or multiple wavelengths, a white light source of a multi-wavelength band, tungsten- Halogen lamps (QTH lamp), laser diodes (LD), light emitting diodes (LEDs) and the like can be used, and the light provided therefrom is collected through the optical system or is incident on the prism 2 in parallel.

In addition, the light source 14 may be configured as an extended light source 14 to provide an incident light extended to the substrate 4 having the T-shaped metal structures 10, 10 ′. 14 may further include a beam expander (not shown).

The light receiving unit 16 according to the present invention detects light changed by localized surface plasmon resonance absorption, and changes a resonance angle, a resonance wavelength, or a color change due to resonance absorption of the localized surface plasmon. Near field microscopes, including charge coupled device (CCD) cameras, video cameras, or projection films that include a photomultiplier (PMT) or silicon photodiode (Si-PD) or shape a two-dimensional plane to measure And an optical microscope, a near-field scanning microscope, and a photon scanning through microscope using the prism 2, if necessary, between the light source 14 and the substrate 4 or between the light receiving portion 16 and the substrate 4. A polarizer, preferably a variable polarizer (not shown), may be provided in between.

Here, the reflected light is detected by the light receiving unit 16, the light receiving unit 16 can quantitatively measure changes in resonance conditions due to resonance absorption of localized surface plasmons, for example, changes in resonance angle or resonance wavelength. It may be configured to have a function.

In this case, the light source 14 and the light receiving unit 16 may be operated using a reflection method.

In order to operate in the reflection method, incident light is incident through the prism 2 in the direction in which the metal structure is fixed, and the changed light is reflected in the incident direction from the mirror surface where it is possible to be detected by the light receiving unit 16.

The sensor further comprises a prism 2 optically coupled to the substrate 4 in order to operate in a reflective manner as described above, and incident light passes through the prism 2 to allow the T-shaped metal structure 10, 10 ′ to pass through. The incident light and the changed light cause total internal reflection and are reflected back through the prism 2.

In this manner, the incident light extended by the beam expander of the light source 14 is polarized in the p-mode (TM-mode) while passing through the polarizer and is incident on the prism 2 at a constant angle. Here, the polarization of the p-mode (or TM mode) means that the magnetic field component of the light crosses the incident surface, and the electric field component vibrates in a direction parallel to the incident surface.

At this time, it is preferable to provide an optical coupling by providing an index matching oil (not shown) between the substrate 4 and the prism 2, and in order to obtain the best effect, the substrate 4 and the prism It is preferable to match the refractive index of (2) and a matching oil. At this time, incident light incident through the prism 2 induces surface plasmons localized on the surfaces of the T-shaped metal structures 10 and 10 'past the substrate 4.

The sensor described above has an array of nano-sized T-shaped metal structures 10, 10 ′ arranged on top of the substrate 4 to induce localized surface plasmon effects. Thus, the sensor may have an improved sensitivity than when using the conventional surface plasmon effect.

By constructing a sensor using the localized surface plasmon effect by arranging the T-shaped metal structures 10 and 10 'arranged on top of the metal thin film 8 as described above, it is possible to use a variety of resonance conditions and to measure more variously. It is possible to employ the method.

Hereinafter, the present invention will be described in detail through examples. However, the following examples are only for illustrating the present invention in detail and are not intended to limit the scope of the present invention by these examples.

<Example 1>

At 1 atm, the chromium was deposited to a thickness of 2 nm using a vapor deposition machine [Samhan Vacuum, South Korea] on the top of the substrate after the substrate was made of a transparent dielectric.

Then, gold was deposited to a thickness of 40 nm on the chromium layer using a vacuum evaporator [Samhan Vacuum, Korea]. A photoresist was coated on the upper end, and heat cured, and then the T-shaped structure was transferred to the upper end of the photoresist with an electron beam. Thereafter, a portion of the electron beam irradiated with the developer was washed and removed to form a photoresist pattern to which the nanostructure shape was transferred.

Then, gold was deposited to a thickness of 20 nm on the photoresist pattern using a vacuum evaporator to form a T-shaped metal structure. Finally, the photoresist pattern remaining in the lift-off manner was washed away with sulfuric acid in dilute solution to form an array of nanometer-sized T-shaped metal structures.

Next, a prism made of BK7 [PS911, THORLABS, USA] was placed on a surface plasmon resonance sensor chip of the present invention in which a chromium layer, a gold layer, and a T-shaped structure were sequentially stacked. , USA], and reflectance in the absence and the presence of the sample was measured using a laser or laser diode [IEC825, MELLESGRIOT, USA] with TM-polarized light and wavelength λ of 633 nm as a light source. .

The result is shown in FIG.

As shown in Fig. 2 and 4, in the conventional surface plasmon sensor structure, the change in the resonance angle with or without the sample does not appear large, but when the T-shaped metal structure is distributed periodically, the interval between the structures is 100 nm In the case of between and 200 nm, the change of the resonance angle is increased by more than 10 times, and as a result, an effect of improving sensitivity is obtained.

<Example 2>

The sensor was manufactured under the same conditions as in Example 1, but the T-shaped metal structure of Example 1 was manufactured in a form in which GF was changed from 0 to 1, and the sensitivity change according to GF was measured.

The results are shown in FIGS. 5 to 8.

<Example 3>

Sensors were prepared under the same conditions as in Example 1 and Example 2, but instead of the T-shaped metal structures of Examples 1 and 2, an inverted T-shaped metal structure was manufactured to measure sensitivity change according to GF.

The results are shown in FIGS. 5 to 8.

As shown in FIG. 5, the inverse T-shaped metal structure has a limited sensitivity improvement, but the T-shaped metal structure generally has better sensitivity than the inverse T-shaped metal structure, and particularly has a GF value of 0.5 or 0.8. In this case, it was confirmed that the sensitivity can be improved more than 40 times compared to the existing surface plasmon sensor.

As shown in FIG. 6, the figure of the T-shaped and the inverted T-shaped metal structure shows the maximum sensitivity interval according to each GF, and the lines connected up and down improve the sensitivity by 20 times or more compared with the conventional surface plasmon sensor. It shows the range of metal nanostructure spacing that can be expressed, and the gap between the T-shaped and inverted T-shaped metal structures, which can achieve the maximum sensitivity improvement, is wider than that of the inverted T-shaped metal structures. Sensitivity is improved more than 20 times. That is, in order to manufacture a metal structure and implement it as a sensor, the longer the interval between the aligned metal structures is, the easier it is to manufacture. It was confirmed that it is easier than to prepare a structure.

Specifically, the sensor having a sensitivity 20 times higher than the conventional sensor has a T-shaped metal structure in the range of 116 to 124 nm when the spacing of the T-shaped metal structure for the GF is 0.2, and in the range of 118 to 145 nm when 0.3, It has been shown to be prepared in the range of 120 to 145 nm at 0.4, 105 to 172 nm at 0.5, 96 to 143 nm at 0.6, 70 to 96 nm at 0.7 and 95 to 135 nm at 0.8.

As shown in FIG. 7 and FIG. 8, the change in the SPR CAW according to the GF and the change in the MRR according to the GF showed more improved characteristics when the sensor having the T-shaped metal structure was used.

As described above, those skilled in the art will understand that the present invention can be implemented in other specific forms without changing the technical spirit or essential features. Therefore, it should be understood that the embodiments described above are all illustrative and not restrictive. The scope of the present invention should be construed as being included in the scope of the present invention all changes or modifications derived from the meaning and scope of the claims to be described later rather than the detailed description and equivalent concepts thereof.

The present invention has an effect of inducing a local surface plasmon resonance phenomenon by providing a metal thin film and a T-shaped metal structure on the substrate, thereby improving the measurement sensitivity of the sensor.

Claims (8)

In the sensor for analyzing the sample 12 adjacent to the conductor thin film using the surface plasmon resonance phenomenon, prism; A substrate provided on top of the prism; A metal thin film provided on the substrate; At least one T-shaped metal structure provided on the top of the metal thin film; A light source provided at a lower end side of the substrate to be spaced apart by a predetermined distance to emit incident light passing through the substrate and incident on the metal thin film; A local surface plasmon sensor including a light receiving unit provided on the lower side of the substrate to be spaced apart by a predetermined distance to detect the light changed by the localized surface plasmon resonance absorption phenomenon for the incident light. The method of claim 1, A local surface plasmon sensor, characterized in that the binding metal layer is provided between the substrate and the metal thin film layer. The method of claim 1, Wherein the interval at which the T-shaped metal structures are aligned is shorter than the wavelength of incident light. The method of claim 1, The T-shaped metal structure may be formed of gold (Au), silver (Ag), platinum (Pt), palladium (Pd), copper (Cu), silicon (Si), germanium (Ge), aluminum (Al), or a mixture thereof. Topical surface plasmon sensor, characterized in that formed. The method of claim 1, In the preparation of the T-shaped metal structure, the interval of the T-shaped metal structure for GF is 0.2 in the range of 116 to 124 nm, 0.3 in the range of 118 to 145 nm, 0.4 in the range of 120 to 145 nm, and 0.5 in the range of 105 to 172. Local surface plasmon sensor, characterized in that it is produced in the range of 96 to 143 nm in the range of 0.6, in the range of 70 to 96 nm at 0.7, 95 to 135 nm at 0.8. The method of claim 1, The T-shaped metal structure is made of a width of 20 to 200 nm, a thickness of 10 to 100 nm, the local surface plasmon sensor, characterized in that the spacing between each T-shaped metal structure is made of 50 to 500 nm. The method of claim 1, A local surface plasmon sensor, characterized in that the distance between the T-shaped metal structure is between 50 to 200 nm. Method for measuring a sample using the sensor according to any one of claims 1 to 7.

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