KR102096859B1 - Method for real time sensing of organic solvent - Google Patents

Abstract

The present invention, a flow cell (Flow cell) provided to allow a solution to flow, a photonic crystal mounted in the flow cell so that the solution flows, and a white light source (white light source) for incident white light on the photonic crystal, A lens for focusing the white light supplied from the white light source, incident on the photonic crystal, and collecting reflected light from the photonic crystal flowing through the organic solvent, and a CCD for collecting and analyzing the reflected light emitted from the lens It relates to an optical sensor capable of real-time analysis of an organic solvent, and a method for analyzing the organic solvent in real time, comprising a spectrometer (CCD Spectrometer). According to the present invention, a change in diffraction wavelength by an organic solvent can be measured in real time by using a photonic crystal capable of causing wavelength shift of electromagnetic waves as a crystal having a periodic porous structure.

Description

Method for real-time analysis of organic solvents {Method for real time sensing of organic solvent}

The present invention relates to an optical sensor capable of real-time analysis of an organic solvent and a method for analyzing the organic solvent in real time, and more specifically, as a crystal having a periodic porous structure, a photonic crystal capable of causing wavelength shift of electromagnetic waves. It relates to an optical sensor that can measure the change in the diffraction wavelength by the organic solvent in real time and a method for analyzing the organic solvent in real time.

In general, the color of an object can be said to be the color of the wavelength of light reflected from visible light reaching the object. Visible light consists of several wavelengths. The light incident on the object causes constructive and destructive interference, and the light of the wavelength causing the canceling interference disappears, and the light of the wavelength causing the constructive interference is reflected.

When light having a certain wavelength region meets an object, some of them pass by refraction, and some of them refract or reflect in a specific direction, so that a specific color selectively enters our eyes.

A material that has a structure that can utilize the optical properties of a material or is made to have a structure is called a photonic crystal. For example, it is also a photonic crystal that reflects only light of a specific wavelength. There is a band gap in which electrons do not exist due to the periodic arrangement of atomic nuclei. When dielectrics ranging in size from hundreds of nanometers to several micrometers are arranged at regular periods, a photonic bandgap in which no specific wavelength photon exists is formed inside the dielectric.

Briefly explaining the principle of the bandgap appearing in the photonic crystal, when the dielectrics are arranged at regular intervals, the light passing through the dielectrics is determined by Bragg`s law, 2 d sin θ = n λ. The light of the wavelength corresponding to the period reflects. Since the same cycle is repeated repeatedly, light of a specific wavelength among the light that passes through is reflected every time it passes through the dielectric, so the wavelength corresponding to the cycle does not exist inside the regularly arranged dielectric, and all are reflected.

After the principle that the optical band gap appeared due to such a regular structure was reported, many studies have been conducted to prepare a photonic crystal having 1, 2, and 3 dimensional regularity.

The production of such photonic crystals can be made using photolithography, ion beam etching, holographic lithography, inkjet, micro robotics, self-assembly, and the like.

The photo-lithography method, which is a top-down method and the method using ion beam etching, has the advantage of being able to fabricate photonic crystals with high precision as a technique for making circuits of existing silicon semiconductors, but the process cost is high and the large-area three-dimensional photonic crystal It has the drawback that it takes a lot of time to make it.

On the other hand, self-assembly, which is a bottom-up method, can manufacture a large-area photonic crystal in a short time at a low cost, but has a disadvantage in that it is difficult to produce a uniform photonic crystal without defects.

Republic of Korea Registered Patent Publication No. 10-1040805

The problem to be solved by the present invention is a crystal having a periodic porous structure, an optical sensor capable of measuring the change in the diffraction wavelength by an organic solvent in real time using a photonic crystal capable of causing wavelength shift of electromagnetic waves and organic It is to provide a method for analyzing the solvent in real time.

The present invention, a flow cell (Flow cell) provided to allow a solution to flow, a photonic crystal mounted in the flow cell so that the solution flows, and a white light source (white light source) for incident white light on the photonic crystal, A lens for focusing the white light supplied from the white light source, incident on the photonic crystal, and collecting reflected light from the photonic crystal flowing through the organic solvent, and a CCD for collecting and analyzing the reflected light emitted from the lens It includes a spectrometer (CCD Spectrometer), the photonic crystal is a crystal that can cause a wavelength shift (shift) of electromagnetic waves, a plurality of dielectric nanotubes having nano pores are arranged to form an array, and the dielectric nanotubes are mutually It has a plurality of spaced apart nodes, and the nodes are said genetic Has a shape that is vertically protruded with respect to the length of the nanotubes, the nanotubes dielectric provides an optical sensor capable of real-time analysis of the organic solvent, characterized in that consisting of TiO _2, Al ₂ O ₃ or SiO _2.

It is preferable that the average spacing between the nodes of the dielectric nanotubes is 50 to 300 nm.

It is preferable that the average diameter of the nanopores is 5 to 900 nm.

The organic solvent may include methanol, ethanol or isopropyl alcohol.

In addition, the present invention, the step of mounting a photonic crystal in a flow cell (Flow cell) provided to allow the solution to flow, and the step of injecting a white light source (white light source) through the lens (Lnes) on the photonic crystal, the flow Causing an organic solvent to flow in the photonic crystal mounted in the cell, collecting reflected light from the photonic crystal through which the organic solvent flows through the lens, and collecting the reflected light from the lens through a CCD spectrometer ) And collecting and analyzing in real time a change in the diffraction wavelength caused by the organic solvent flowing in the photonic crystal, wherein the photonic crystal is a crystal capable of causing wavelength shift of electromagnetic waves. As, a plurality of dielectric nanotubes having nano-pores are arranged to form an array, the dielectric The nanotubes have a plurality of nodes spaced apart from each other, and the nodes have a shape protruding perpendicular to the length of the dielectric nanotubes, and the dielectric nanotubes are made of TiO ₂ , Al ₂ O ₃ or SiO ₂ It provides a method for analyzing the organic solvent, characterized in that in real time.

It is preferable that the average spacing between the nodes of the dielectric nanotubes is 50 to 300 nm.

It is preferable that the average diameter of the nanopores is 5 to 900 nm.

The organic solvent may include methanol, ethanol or isopropyl alcohol.

According to the present invention, a change in diffraction wavelength by an organic solvent can be measured in real time by using a photonic crystal capable of causing wavelength shift of electromagnetic waves as a crystal having a periodic porous structure. The photonic crystal includes an array of dielectric nanotubes having a plurality of nodes, and the array of dielectric nanotubes is a crystal having a periodic porous structure, through which a wavelength shift of electromagnetic waves may be induced.

1 is a view schematically showing equipment for performing anodizing and applying a voltage pulse to form a photonic crystal.
FIG. 2 is a diagram illustrating an example of a pattern of voltage pulses applied for the production of a photonic crystal.
FIG. 3 is a diagram schematically showing a diffraction of visible light in a periodic lattice of a photonic crystal (an array of dielectric nanotubes having multiple nodes).
4 is a schematic diagram showing the configuration of a sensor capable of analyzing an organic solvent in real time using a photonic crystal.
5 is a view showing a voltage pulse pattern applied in Experimental Example 1.
6 is a field emission scanning electron microscope (FE-SEM) photograph showing a side and a plane of a TiO ₂ nanotube array prepared according to Experimental Example 1.
FIG. 7 is a graph showing a reflection spectrum for a photonic crystal (array of TiO ₂ nanotubes having multiple nodes) prepared according to Experimental Example 1, in which ethanol (EtOH), an organic solvent in TiO ₂ nanotubes, is It was measured in the entered state.
8 is a view showing the observation of a real-time wavelength change according to the concentration change of ethanol for a photonic crystal (array of TiO ₂ nanotubes having multiple nodes) prepared according to Experimental Example 1.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the following embodiments are provided to those of ordinary skill in the art to fully understand the present invention and may be modified in various other forms, and the scope of the present invention is limited to the embodiments described below. It does not work. The same reference numerals in the drawings refer to the same elements.

Hereinafter, the term “nano” refers to a size in the range of 1 to 1000 nm as a size in nanometers, and the nanotube has a tubular structure and is used to mean that the size of the inner diameter is nano.

An optical sensor capable of real-time analysis of an organic solvent according to a preferred embodiment of the present invention includes a flow cell provided to allow a solution to flow, a photo crystal mounted in the flow cell to flow the solution, and the photo crystal A white light source for injecting white light onto the lens, and a lens for focusing the white light supplied from the white light source to enter the photonic crystal and collect reflected light from the photonic crystal through which the organic solvent flows (Lnes ), And a CCD spectrometer for collecting and analyzing the reflected light from the lens. The photonic crystal is a crystal that can cause a wavelength shift of electromagnetic waves, and dielectric nanotubes having nano pores. A plurality of are arranged to form an array, the dielectric nanotube Has a plurality of bars that are spaced apart from each other, the joint has a shape projecting perpendicularly with respect to the length of the dielectric nano-tube, the dielectric nano-tube is made of TiO _2, Al ₂ O ₃ or SiO _2.

It is preferable that the average spacing between the nodes of the dielectric nanotubes is 50 to 300 nm.

It is preferable that the average diameter of the nanopores is 5 to 900 nm.

The organic solvent may include methanol, ethanol or isopropyl alcohol.

The method for analyzing an organic solvent in real time according to a preferred embodiment of the present invention includes mounting a photonic crystal in a flow cell provided to allow a solution to flow, and a white light source to a lens (Lnes ) Through the photonic crystal, allowing an organic solvent to flow through the photonic crystal mounted in the flow cell, and collecting reflected light from the photonic crystal through which the organic solvent flows through the lens, Collecting the reflected light from the lens using a CCD spectrometer (CCD Spectrometer) and analyzing and analyzing in real time the change in the diffraction wavelength caused by the organic solvent flowing in the photonic crystal, wherein the photonic crystal is , As a crystal that can cause a wavelength shift of electromagnetic waves, the nano-pores A plurality of all nanotubes are arranged to form an array, and the dielectric nanotubes have a plurality of nodes spaced apart from each other, and the nodes have a shape protruding perpendicular to the length of the dielectric nanotubes, and the dielectric nanotubes The tube is made of TiO ₂ , Al ₂ O ₃ or SiO ₂ .

It is preferable that the average spacing between the nodes of the dielectric nanotubes is 50 to 300 nm.

It is preferable that the average diameter of the nanopores is 5 to 900 nm.

The organic solvent may include methanol, ethanol or isopropyl alcohol.

Hereinafter, the photonic crystal (photonic crystal) and its manufacturing method will be described in more detail.

Photonic crystal (photonic crystal), a crystal that can cause a wavelength shift (shift) of electromagnetic waves, a plurality of dielectric nanotubes having nano pores are arranged to form an array, and the dielectric nanotubes have a plurality of nodes spaced apart from each other Has, the node has a form protruding perpendicular to the length of the dielectric nanotubes, the dielectric nanotubes are made of TiO ₂ , Al ₂ O ₃ or SiO ₂ .

It is preferable that the average spacing between the nodes of the dielectric nanotubes is 50 to 300 nm.

It is preferable that the average diameter of the nanopores is 5 to 900 nm.

1 is a diagram schematically showing equipment for performing anodizing and applying a voltage pulse to form an array of dielectric nanotubes having a plurality of nodes.

1, the equipment for performing anodizing and applying a voltage pulse includes an electrochemical bath 10, an electrolyte 20, an anode 30, a cathode 40, and a power supply ( 50) and a computer (60). The equipment may further include a cooling circulator (70), a thermostatic bath (80), a multimeter (90), a magnetic stirrer (95), and the like.

The anodizing process is a process of forming an oxide film by applying electrical force to Ti, Al, Si or their alloys in an electrolyte solution, a relatively easy manufacturing process, and a low manufacturing cost. Ions, such as fluorine (F) ions, are added to the electrolyte to cause electrical dissociation simultaneously with oxidation to form a porous oxide film. An array of dielectric nanotubes by an anodizing process is formed due to repeated oxidation and dissociation reactions, and the dielectric nanotube array is formed in a direction perpendicular to the surface.

A voltage pulse is applied while anodizing Ti, Al, Si, or an alloy thereof using the electrolyte 20 containing fluorine (F) to form an array of dielectric nanotubes having a plurality of nodes.

In the anodizing, an anode 30 and a cathode 40 in which Ti, Al, Si, or alloys thereof are disposed are spaced apart from each other, and the anode 20 in the electrolytic solution 20 in the electrolytic cell 10 containing the electrolyte 20 is ( 30) and the negative electrode 40 are contained, and the voltage is applied to the positive electrode 30 and the negative electrode 40. The positive electrode 30 and the negative electrode 40 are spaced apart from each other at a predetermined distance, and the positive electrode 30 is Ti, Al, Si or an alloy thereof, which is the same component as the metal component contained in the array of dielectric nanotubes to be obtained. Use As an example of such an alloy, an alloy containing a titanium (Ti) or aluminum (Al) component, such as a Ti-6Al-4V alloy, is exemplified.

Important factors for anodizing include electrolyte 20, applied voltage, anodizing time, temperature, and the like.

The electrolytic solution 20 for the anodizing is sulfuric acid (H ₂ SO ₄ ), phosphoric acid (H ₃ PO ₄ ), citric acid, oxalic acid, ethylene glycol (Ethylene Glycol), glycerol (Glycerol), dimethyl It may be a solution in which NH ₄ F is mixed with one or more solutions selected from sulfoxide (DMSO).

In order to form an array of dielectric nanotubes, Ti, Al, Si or alloys thereof are prepared and mounted on the anode 30. As the cathode 40, an acid-resistant metal electrode such as platinum (Pt), tantalum (Ta), silver (Ag), or gold (Au) is used. The anode 30 is installed so as to be immersed in the electrolyte 20 by maintaining a constant distance from the cathode 40. The positive electrode 30 and the negative electrode 40 are connected to a power supply means 50 for applying voltage or current. The voltage difference between the anode 30 and the cathode 40 is appropriately adjusted in consideration of the diameter size of the formed dielectric nanotube, the length of the dielectric nanotube, and the spacing between nodes. The voltage applied to form the array of dielectric nanotubes by the anodizing is preferably applied such that the voltage difference between the anode 30 and the cathode 40 is less than or equal to 100V. The array of dielectric nanotubes formed by the anodizing has a tubular structure, and is preferably formed to have an inner diameter (diameter of nanopore) having a size of 5 to 900 nm.

The electrolytic cell 10 may be provided with a cooling circulator 70 to prevent a rapid temperature rise due to an exothermic reaction during the anodizing process and to increase the uniformity of the electrolysis or chemical reaction, and the cooling means 70 It is preferable to prevent the temperature of the electrolytic solution from rapidly increasing as the cooling water circulates.

In addition, a constant temperature bath 80 may be provided to maintain a constant temperature in the electrolytic bath 10. The electrolytic bath 10 is located inside the thermostat 80, so that the temperature of the electrolytic solution 20 can be kept constant. It is preferable to set the temperature of the electrolytic solution 20 in a range of about 0 to 50 ° C.

In addition, a magnetic stirrer 95 may be provided to stir the electrolytic solution 20 so that the anodizing process can easily occur.

Hereinafter, a process in which TiO ₂ nanotubes, which are examples of dielectric nanotubes, are formed by an anodizing process will be described.

The electrolyte 20 smoothly moves charged electrons or ions to form a titanium oxide film (TiO ₂ ) on the surface of titanium (Ti) or titanium alloy. Titanium metal ions (Ti ⁴⁺ ) are dissolved in the electrolyte 20 at the interface between the electrolyte 20 and the oxide film, and the electrolyte 20 is combined with O ² , OH ^- ions to form an oxide film at the interface between the oxide film and the metal. do.

Looking at the anodizing process, the electrolytic solution 20 in the water molecule (H ₂ O), by the electrolysis of hydrogen ions as in reaction scheme 1 below (H ⁺⁾ and hydroxyl ion (OH ^-) are delivered in.

[Scheme 1]

^{_{H 2 O → H + + OH}} -

Hydrogen ions (H ⁺ ) move toward the cathode 40 and are released into hydrogen gas (H ₂ ) by bonding with electrons between the electrolyte solution 20 and the surface of the cathode 40.

Hydroxyl ion (OH ^-) can be separated from the natural oxide film moved, and formed on the anode 30 toward the cathode surface 30 into oxygen ions (O ^2-) and hydrogen ions (H ^+). At this time, oxygen ions (O ^2-) are to penetrate the native oxide film and a natural oxide film of titanium (or titanium alloys), titanium ions between (Ti ^{+ 4)} reacts with the titanium oxide film as shown in scheme 2 below (TiO ₂₎ been separated To form.

[Scheme 2]

Ti ⁴⁺ + 2O ^2－ → TiO ₂

In addition, hydrogen ions (H ⁺ ) react with the titanium oxide film (TiO ₂ ) to partially break the bond between titanium (Ti) and oxygen to form hydroxides, which are dissolved in the electrolytic solution 20. That is, oxide etching occurs on the surface between the titanium oxide film (TiO ₂ ) and the electrolyte solution 20. Thus, a titanium oxide film (TiO ₂ ) is formed at the interface between the natural oxide film and titanium (or titanium alloy).

When synthesized and expressed as a reaction scheme, it is as shown in the following reaction scheme 3.

[Scheme 3]

_{Ti + 2H 2 O → TiO 2} + 4H + + 4e -

Water molecules in the electrolyte solution meet with titanium at the anode 30 as shown in Reaction Scheme 3 to form a titanium oxide film (TiO ₂ ).

The thus formed titanium oxide film (TiO ₂ ) is dissociated as shown in Scheme 4 by a small amount of fluorine ion (F ⁻ ) contained in the electrolyte solution.

[Reaction Scheme 4]

_{^{TiO 2 + 6F - + 4H +}} → [TiF 6] 2- + 2H 2 O

This dissociation action occurs over the entire titanium oxide film (TiO ₂ ) and forms an array of nanotubes. In addition, as the anodizing time increases, an oxidation reaction of Scheme 3 and a dissociation reaction of Scheme 4 occur simultaneously, from which an array of TiO ₂ nanotubes can be obtained.

The voltage pulse applied between the anode 30 and the cathode 40 is applied by a power supply 50, and the power supply means 50 is connected to the computer 60. The computer 60 includes a pattern (shape) of a voltage pulse applied through the power supply means 50, a second voltage (high voltage) and a first voltage (low voltage), a voltage applying speed, and a step-up voltage. It plays a role in controlling the speed, the decompression speed, the number of voltage pulses applied, and the time when one voltage pulse is applied.

The voltage pulse is a pulse that is decompressed from the second voltage to the first voltage after being boosted from a first voltage (low voltage) to a second voltage (high voltage) higher than the first voltage.

The voltage pulse may be a square wave, a trapezoidal wave, a triangular wave, or a pulse having a mixture thereof, and is preferably a voltage pulse in the form of a trapezoidal wave.

The voltage difference between the first voltage (low voltage) and the second voltage (high voltage) is preferably 10 to 90V. When a voltage pulse is applied, a voltage higher than or equal to a low voltage (first voltage) is always applied between the anode 30 and the cathode 40.

2 is a diagram illustrating an example of a pattern of voltage pulses applied for the production of a photonic crystal, and shows an example of a trapezoidal voltage pulse.

In FIG. 2, Step I represents 'first voltage ramping', Step II represents 'voltage ramping', Step III represents 'high voltage holding', Step IV represents 'voltage dropping', and Step V represents 'low voltage holding'. . 2, Step II to Step V form a pulse cycle. During the anodizing process, a voltage pulse is applied so that the pulse cycle is formed multiple times.

The trapezoidal voltage pulse is a pulse having a time to be maintained at a high voltage (second voltage) as in Step III, and a voltage pulse in the form of a triangular wave has no time to be maintained at a high voltage (second voltage) as in Step III (holding at a high voltage) Pulse).

The voltage pulse in the form of a square wave means that the slope of the voltage / time is vertical or close to the vertical in the step II and step IV sections of FIG. 2, and has a rectangular waveform.

When applying a voltage pulse in the form of a trapezoidal wave or a triangular wave, the step-up and depressurization rates may affect the microstructure of the dielectric nanotube array, which is more important in the process of wave form along with other process variables. Is a variable. The step-up speed refers to a value obtained by dividing the voltage difference between the high voltage (second voltage) and the low voltage (first voltage) by the time taken to increase (boost) the voltage from the low voltage (first voltage) to the high voltage (second voltage), and depressurize. Speed refers to a value obtained by dividing the voltage difference between a high voltage and a low voltage by the time it takes to drop (decompress) a voltage from a high voltage to a low voltage. It is preferable that the step-up and depressurization rates are about 1 to 15 V / sec, more specifically about 3 to 7 V / sec. As an example of the trapezoidal waveform voltage pulse, the high voltage (second voltage) is 60 V, the low voltage (first voltage) is 40 V, the high voltage (second voltage) holding time is 180 sec, and the low voltage (first voltage) holding time. Is 180 sec, and the step-up speed rising from low voltage (first voltage) to high voltage (second voltage) is 5 V / sec, and the step-down speed falling from high voltage (second voltage) to low voltage (first voltage) is 5 V / sec. to be.

The interval (or distance) between the nodes of the dielectric nanotubes can be controlled by adjusting the time (step 2 to Step IV in FIG. 2) at which one voltage pulse is applied. If the application time of one voltage pulse is large, the distance (or distance) between the nodes and nodes of the dielectric nanotubes becomes large, and when the application time of one voltage pulse is small, the interval (or distance) between the nodes and nodes It becomes smaller.

The form of the voltage pulse applied by the power supply means 50, the second voltage (high voltage) and the first voltage (low voltage) of the voltage pulse, the number of times the voltage pulse is applied, the application time of one voltage pulse, the boosting speed, and the decompression speed The back can be computer controlled by a program on the computer 60.

When a voltage pulse is applied while anodizing Ti, Al, Si or an alloy thereof, an array of dielectric nanotubes having a plurality of nodes is formed. The array of dielectric nanotubes has a structure in which a plurality of dielectric nanotubes are arranged adjacently.

FIG. 3 is a diagram schematically showing a diffraction of visible light in a periodic lattice of a photonic crystal (an array of dielectric nanotubes having multiple nodes). In FIG. 3, reference numeral '110' denotes a dielectric nanotube, reference numeral '112' denotes a node of the dielectric nanotube, reference numeral '114' denotes a pore of the dielectric nanotube, and reference numeral '116' a dielectric substance. It is the unit lattice of the nanotube, and it represents the gap between nodes. An array of dielectric nanotubes having a plurality of nodes is a crystal having a periodic porous structure, and through this structure, wavelength shift of electromagnetic waves may be induced.

The node 112 of the dielectric nanotube has the shape of a bamboo node. These nodes 112 have a shape that protrudes perpendicular to the length of the dielectric nanotube 110, and each node 112 is spaced apart from each other. It is preferable that the gap (length) between the nodes is about 50 to 300 nm.

It is preferable that the size of the inner diameter (pore 114 diameter) of the dielectric nanotube is about 5 to 900 nm.

The array of dielectric nanotubes having a plurality of nodes thus manufactured may be used as a photonic crystal.

The array of dielectric nanotubes prepared by the above method can be used as an optical interference biosensor, and is more stable in an acidic atmosphere than SiO ₂ .

The photonic crystal including the above-described array of dielectric nanotubes can control light without loss, and thus can be utilized in optical integrated circuits such as miniaturized lasers, optical waveguides, filters, dividers, mixers, and control the speed or direction of light. Since it can increase the efficiency of LED and solar cells, it is sensitive to external stimuli such as light, temperature, pressure, pH, electricity, and dielectric constant, so application to various sensors is expected.

4 is a schematic diagram showing the configuration of an optical sensor capable of analyzing an organic solvent in real time using a photonic crystal.

Referring to FIG. 4, an optical sensor capable of real-time analysis of an organic solvent includes a flow cell 240 provided to allow a solution to flow and a photonic crystal mounted in the flow cell 240 to allow the solution to flow. (100), a white light source (210) for injecting white light onto the photonic crystal (100), and the white light supplied from the white light source (210) are focused on the photonic crystal (100). A lens (Lnes) 230 for collecting reflected light from the photonic crystal 100 through which the organic solvent flows, and a CCD spectrometer (CCD Spectrometer) for collecting and analyzing the reflected light from the lens 230 ( 220).

The white light source 210 may be a tungsten lamp or the like. It is preferable to focus the white light incident on the photonic crystal using a lens (Lnes) 230 to be included in a circle having a diameter of 0.1 to 1 mm.

The reflected light coming out of the photonic crystal 100 may be collected using a CCD spectrometer 220.

The organic solvent may include methanol, ethanol or isopropyl alcohol.

After the photonic crystal 100 is mounted on the flow cell 240 and distilled water is flowed through the flow cell 240 on which the photonic crystal 100 is mounted, intensity is adjusted according to the wavelength of the reflected light spectrum using the CCD spectrometer 220. ) Is measured, and after flowing an organic solvent to the flow cell 240 equipped with the photonic crystal 100, the intensity of the intensity is changed according to the wavelength of the reflected light spectrum using the CCD spectrometer 220. You can.

Hereinafter, a method for analyzing an organic solvent in real time according to a preferred embodiment of the present invention will be described in detail.

The photonic crystal 100 is mounted in a flow cell 240 provided to allow a solution to flow.

A white light source is incident on the photonic crystal through a lens. It is preferable to focus the white light incident on the photonic crystal using a lens (Lnes) 230 to be included in a circle having a diameter of 0.1 to 1 mm.

An organic solvent flows through the photonic crystal 100 mounted in the flow cell 240. For example, the organic solvent flows from the inlet portion In of the flow cell 240 to the outlet portion Out. It is preferable that 100% concentration of distilled water is flowed for a certain period of time while the diffraction by visible light is being observed, and a solution containing an organic solvent is flowed into the flow cell. The organic solvent may include methanol, ethanol or isopropyl alcohol.

The reflected light coming out of the photonic crystal 100 through which the organic solvent flows is collected through the lens 230.

The reflected light coming from the lens 230 is collected using a CCD spectrometer 220 and analyzed in real time by measuring changes in the diffraction wavelength caused by the organic solvent flowing in the photonic crystal.

The Fabry-Laro interference phenomenon will be described. When mirrors with high reflectivity are placed parallel to each other and light is incident on the mirrors, the light transmitted through the mirrors transmits some of the light on the surfaces of the parallel mirrors, but most of them repeat transmission and reflection. On the opposite side of the incident direction, the number of reflections between the two mirrors is transmitted through the lower mirror, and each light exhibits interference as much as the path difference.

When white light is incident on a photonic crystal having nano-sized pores, an interference pattern related to the optical thickness appears due to a difference in the optical paths of the upper and lower pores formed in the photonic crystal.

Optical thickness refers to the distance between the upper end of the pores and the lower end of the pores on the opposite side in the longitudinal direction of the photonic crystal as described above, that is, the length of the space in the photonic crystal.

Equation 1 shows the relationship between the refractive index (n) and the optical thickness (L).

[Equation 1]

mλ = 2nL

Where m is the interference order, λ is the maximum interference wavelength obtained from the m order, n is the refractive index of the photonic crystal and the organic solvent contained in the photonic crystal, and L is the optical thickness of the photonic crystal.

The optical thickness L can be changed according to the concentration of the electrolyte solution, voltage, anodization time, and the like. As the length of the optical thickness increases, the number of fringes increases, and the characteristics of the interference wavelength change.

When white light is irradiated on the photonic crystal, a Fabry-Far fringe-type reflection wave appears due to a difference in optical paths between the top of the photonic crystal and the bottom of the pore.

As the organic solvent is administered, the Fabri-Faro fringe-shaped reflection waveform can confirm the change of the intensity of the white light and the shift of the reflection wavelength.

A fast fourier transformation (FFT) is attempted on the spectrum of the fringe-type reflected wavelength for white light. The fast Fourier transform is an algorithm designed to reduce the number of operations when calculating a discrete fourier transform using an approximation formula based on the Fourier transform.

The fast Fourier transform is a function calculation method that converts temporal flow of sound information into frequency flow.

The reflected light spectrum obtained from the photonic crystal is subjected to a fast Fourier transform (FFT).

A peak having a specific optical thickness can be obtained, and this optical thickness is referred to as an effective optical thickness. The effective optical thickness is shifted according to the change of the spectrum according to the size and refractive index of the organic solvent contained in the photonic crystal.

Hereinafter, experimental examples according to the present invention are specifically presented, and the present invention is not limited by the following experimental examples.

<Experimental Example 1>

While performing anodizing using an electrolyte solution containing fluorine (F), a trapezoidal voltage pulse was applied to prepare a photonic crystal (array of TiO ₂ nanotubes) having a plurality of nodes.

An electrolyte solution in which 0.5 parts by weight of NH ₄ F was mixed with 100 parts by weight of a solution in which 89.1% by weight of ethylene glycol and 10.9% of water (H ₂ O) was mixed was used. The temperature of the electrolytic solution was about 30 ° C.

In order to obtain a TiO ₂ nanotube array of appropriate microstructure, a computer is connected to a power supply means, the shape of the voltage pulse, the second voltage and the first voltage of the voltage pulse, the number of times the voltage pulse is applied, the application time of one voltage pulse, The step-up speed, the step-down speed, etc. were computer-controlled by the program.

As shown in FIG. 5, a voltage pulse in the form of a trapezoidal wave was applied. The high voltage (second voltage) was 60 V, the low voltage (first voltage) was 40 V, and the high voltage (second voltage). The holding time is 180 sec, the low voltage (first voltage) holding time is 180 sec, and the step-up speed rising from the low voltage (first voltage) to the high voltage (second voltage) is 5 V / sec, and the low voltage at the high voltage (second voltage). The decompression rate falling to (first voltage) was controlled to 5 V / sec.

As shown in Fig. 2, Step II to Step V were set as a pulse cycle, and the pulse cycle was repeated 20 times.

6 is a field emission scanning electron microscope (FE-SEM) photograph showing a side and a plane of a TiO ₂ nanotube array prepared according to Experimental Example 1.

Referring to FIG. 6, it was confirmed that the TiO ₂ photonic crystal has a plurality of nodes, and the TiO ₂ photonic crystal has the same shape as the bamboo node. Node of a photonic crystal TiO ₂ having a shape projecting perpendicularly with respect to the length of the TiO ₂ photonic crystal, each node could be seen that the position to be spaced apart from each other. It was also confirmed that a plurality of TiO ₂ nanotubes were arranged adjacent to each other to form an array.

The average spacing (length) between the nodes of the TiO ₂ photonic crystal was about 150 nm.

<Experimental Example 2>

A TiO ₂ photonic crystal prepared according to Experimental Example 1 is mounted on a flow cell as shown in FIG. 4, and 100% concentration of distilled water is flowed for a certain period of time while diffraction by visible light is observed, and ethanol as an organic solvent. The solution containing was flowed into the flow cell.

FIG. 7 is a graph showing a reflection spectrum of a photonic crystal prepared according to Experimental Example 1 (array of TiO ₂ nanotubes having a plurality of nodes), and ethanol (EtOH), an organic solvent, is contained in the TiO ₂ photonic crystal. It was measured in the state.

Referring to FIG. 7, it was confirmed that the wavelength diffracted in the photonic crystal changes according to ethanol contained in the TiO ₂ photonic crystal.

8 is a view showing the observation of a real-time wavelength change according to the concentration change of ethanol for a photonic crystal (array of TiO ₂ nanotubes having multiple nodes) prepared according to Experimental Example 1.

Referring to FIG. 8, it was observed that the wavelength was changed according to the concentration of ethanol.

Since the phase of the TiO ₂ photonic crystal is changed, the diffraction wavelength of the photonic crystal also changes, so it can be confirmed that the optical diffraction change by the second phase can be observed in real time to be used as a sensor.

As described above, the preferred embodiments of the present invention have been described in detail, but the present invention is not limited to the above embodiments, and various modifications are made by those skilled in the art within the scope of the technical spirit of the present invention. This is possible.

10: electrochemical bath
20: electrolyte
30: anode
40: cathode
50: power supply means
60: computer
70: cooling circulator
80: thermostatic bath
90: multimeter
95: magnetic stirrer
100: photonic crystal
110: dielectric nanotube
112: Node of the dielectric nanotube
114: Pore of the dielectric nanotube
116: node spacing of dielectric nanotubes
210: white light source
220: CCD spectrometer
230: Lens
240: Flow cell

Claims (8)

delete delete delete delete Mounting a photonic crystal in a flow cell provided to allow the solution to flow;
Injecting a white light source through the lens onto the photonic crystal;
Flowing distilled water into the flow cell equipped with the photonic crystal;
Allowing an organic solvent to flow through the photonic crystal mounted in the flow cell;
Collecting reflected light from the photonic crystal through which the organic solvent flows through the lens;
Collecting the reflected light from the lens using a CCD spectrometer; And
And measuring and analyzing in real time the change in the diffraction wavelength according to the concentration of the organic solvent flowing in the photonic crystal,
After flowing the distilled water to the flow cell equipped with the photonic crystal, it is measured that the intensity varies according to the wavelength of the reflected light spectrum using the CCD spectrometer.
After flowing the organic solvent to the flow cell equipped with the photonic crystal, it is measured that the intensity changes according to the wavelength of the reflected light spectrum using the CCD spectrometer.
The organic solvent includes methanol, ethanol or isopropyl alcohol,
The photonic crystal,
As a crystal that can cause a wavelength shift of electromagnetic waves,
A plurality of dielectric nanotubes having nano pores are arranged to form an array,
The dielectric nanotubes have a plurality of nodes spaced apart from each other,
The node has a shape protruding perpendicular to the length of the dielectric nanotube,
The dielectric nanotube is a method for analyzing in real time the organic solvent, characterized in that consisting of TiO ₂ , Al ₂ O ₃ or SiO ₂ .
The method of claim 5, wherein the average spacing between the nodes of the dielectric nanotubes is 50-300 nm.
The method for analyzing an organic solvent in real time according to claim 5, wherein the nano pores have an average diameter of 5 to 900 nm.
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