KR20210009524A - Artificial Photonic Nociceptor - Google Patents

Abstract

The present invention relates to an artificial photonic nociceptor. More specifically, the present invention relates to an artificial photonic nociceptor capable of exhibiting threshold properties, non-adaptation properties, allodynia properties, and hyperalgesia properties like nociceptors to light stimulation. The artificial photonic nociceptor comprises: an FTO layer; an ATO layer over the FTO layer; and a zinc oxide layer on the ATO layer, wherein the ATO layer comprises oxygen voids.

Description

Artificial Photonic Nociceptor {Artificial Photonic Nociceptor}

The present invention relates to an artificial optical nociceptor, and more particularly, to an artificial optical nociceptor capable of exhibiting threshold characteristics, non-adaptation characteristics, allodynia characteristics, and hyperalgesia characteristics like a nociceptor to light stimulation.

Nociceptors are one of the body's most important sensory receptors. This is because it recognizes harmful external inputs and transmits pain signals to the central nervous system to avoid potential damage. Typically, nociceptors do not respond below a certain input signal threshold, while responding strongly and rapidly above a threshold. It also exhibits unique characteristics such as thresholds related to the intensity, duration and repetition rate of external stimuli, inadaptation, allodynia, and hyperalgesia. Also, when the noxious signal is removed, the nociceptor is gradually relieved within a time span known as the relaxation period. In an effort to artificially realize these properties, several complex metal oxide semiconductor circuits with complex arrangements have been used, but recent studies have found that they can be replaced with a single memristor.

Memristors, capable of remembering the last operating state, are considered the most promising key elements in next-generation technology. The memristor was first proposed by Chua as the fourth circuit element in 1971 in Non-Patent Document 1, and was experimentally confirmed in HP Lab in 2008 in Non-Patent Document 2. Since then, scientists have observed the hysteresis characteristics of memristors in various materials and attempts have been made to apply them to various fields.

Meanwhile, one of the most important parts of the human body is the eye that operates by receiving an optical signal directly. Nevertheless, no research has been conducted on a device that provides a nociceptor-like function through light input in a self-bias condition.

L. O. Chua, IEEE Trans. Circuit Theory 1971, 18, 507. D. B. Strukov, G. S. Snider, D. R. Stewart, R. S. Williams, Nature 2008, 453, 80.

It is an object of the present invention to provide an artificial optical nociceptor capable of exhibiting threshold characteristics, non-adaptation characteristics, allodynia characteristics, and hyperalgesia characteristics like nociceptors to light stimulation.

In order to solve the above problems, the present invention provides an artificial light pain sensor, FTO layer; An ATO layer over the FTO layer; And a zinc oxide layer over the ATO layer. Including, and the ATO layer provides an artificial light pain sensor containing oxygen voids.

In the present invention, the artificial light pain receptor includes a threshold characteristic indicating a different optical response to a light stimulus less than a threshold value and a light stimulus above a threshold value; Non-adaptation characteristic in which the response does not change even for repeated input of the same stimulus; Allodynia in which the threshold is lowered by strong light stimulation; And hyperalgesia in which a light response is amplified by strong light stimulation. Can represent.

In the present invention, the ATO layer may be generated by depositing an ATO target by performing RF sputtering,

In the present invention, the ATO layer may be subjected to rapid heat treatment after performing RF sputtering,

In the present invention, the zinc oxide layer may be generated by depositing a zinc oxide target by performing RF sputtering.

In the present invention, the ATO layer may have a thickness of 30 to 200 nm, and the zinc oxide layer may have a thickness of 100 to 300 nm.

In the present invention, the artificial light pain sensor may have a transmittance of 65% or more in a visible light region (wavelength 400 to 700 nm).

In order to solve the above problems, the present invention provides a method of manufacturing an artificial light pain sensor, comprising: disposing an FTO layer; Disposing an ATO layer on the FTO layer; And disposing a zinc oxide layer on the ATO layer. Including, wherein the ATO layer includes oxygen voids, it provides a method of manufacturing an artificial light pain sensor.

In the present invention, the artificial light pain receptor includes a threshold characteristic indicating a different optical response to a light stimulus less than a threshold value and a light stimulus above a threshold value; Non-adaptation characteristic in which the response does not change even for repeated input of the same stimulus; Allodynia in which the threshold is lowered by strong light stimulation; And hyperalgesia in which a light response is amplified by strong light stimulation. Can represent.

In the present invention, the ATO layer may be generated by depositing an ATO target by performing sputtering.

According to an embodiment of the present invention, it is possible to provide a transparent artificial light pain sensor capable of detecting damage caused by light.

According to an embodiment of the present invention, it is possible to provide an artificial light pain sensor having a threshold characteristic for light stimulation.

According to an embodiment of the present invention, it is possible to provide an artificial light pain sensor having non-adaptation characteristics to light stimulation.

According to an embodiment of the present invention, it is possible to provide an artificial light pain sensor having allodynia and hyperalgesia properties to light stimulation.

1 is a diagram schematically showing a layered structure of an artificial light pain sensor according to an embodiment of the present invention.
2 is a diagram schematically showing an apparatus for manufacturing an artificial light pain sensor according to an embodiment of the present invention.
3 is a diagram showing an SEM image of a zinc oxide layer of an artificial light pain sensor according to an embodiment of the present invention.
4 is a diagram showing an XRD spectrum of an ATO layer of an artificial light pain sensor according to an embodiment of the present invention.
5 is a diagram showing a crystal structure of ATO according to an embodiment of the present invention.
6 is a view showing the transmittance of the artificial light pain sensor according to an embodiment of the present invention.
7 is a diagram showing an absorbance and a photoluminescence spectrum of an ATO layer according to an embodiment of the present invention.
8 is a diagram showing an SEM image of a layered cross-section of an artificial light pain sensor according to an embodiment of the present invention.
9 is a diagram showing a concentration profile of an element according to a sputtering time in manufacturing an artificial light pain sensor according to an embodiment of the present invention.
10 is a diagram showing an element distribution of an artificial light pain sensor according to an embodiment of the present invention.
11 is a diagram showing a result of measuring IV characteristics of an artificial light pain sensor according to an embodiment of the present invention.
12 is a diagram showing a result of measuring the retention of an artificial light pain sensor according to an embodiment of the present invention.
13 is a diagram showing a result of measuring IV characteristics of an artificial light pain sensor according to an embodiment of the present invention.
14 is a diagram schematically showing a charge transport mechanism of an ATO layer according to an embodiment of the present invention.
15 is a diagram illustrating an optical response to an optical pulse input of an artificial light pain sensor according to an embodiment of the present invention.
16 is a diagram illustrating an optical response to an optical pulse input of an artificial light pain sensor according to an embodiment of the present invention.
17 is a diagram illustrating a light response according to a stimulation intensity of an artificial light pain sensor according to an embodiment of the present invention.
18 is a diagram illustrating a light response to an input of an ultraviolet pulse of an artificial light pain sensor according to an embodiment of the present invention.
19 is a diagram showing a light response according to an intensity of an ultraviolet pulse of an artificial light pain sensor according to an embodiment of the present invention.
20 is a diagram showing a light response according to the intensity of an ultraviolet pulse of an artificial light pain sensor according to an embodiment of the present invention.
21 is a diagram showing a reaction time according to an intensity of an ultraviolet pulse of an artificial light pain sensor according to an embodiment of the present invention.
22 is a diagram showing a light response according to a frequency of an ultraviolet pulse of an artificial light pain sensor according to an embodiment of the present invention.
23 is a diagram showing the characteristics of a pain sensor of an artificial light pain receptor according to an embodiment of the present invention.
24 is a view comparing the mechanism of operation of the artificial light pain sensor and the mechanism of operation of the human eye according to an embodiment of the present invention.

In the following, various embodiments and/or aspects are now disclosed with reference to the drawings. In the following description, for illustrative purposes, a number of specific details are disclosed to aid in an overall understanding of one or more aspects. However, it will also be appreciated by those of ordinary skill in the art that this aspect(s) may be practiced without these specific details. The following description and the annexed drawings set forth in detail certain illustrative aspects of one or more aspects. However, these aspects are exemplary and some of the various methods in the principles of the various aspects may be used, and the descriptions described are intended to include all such aspects and their equivalents.

As used herein, “an embodiment,” “example,” “aspect,” “example,” and the like may not be construed as having any aspect or design described as being better or advantageous than other aspects or designs. .

In addition, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or”. That is, unless specified otherwise or is not clear from the context, "X employs A or B" is intended to mean one of the natural inclusive substitutions. That is, X uses A; X uses B; Or, when X uses both A and B, “X uses A or B” can be applied to either of these cases. In addition, the term "and/or" as used herein should be understood to refer to and include all possible combinations of one or more of the listed related items.

In addition, the terms "comprising" and/or "comprising" mean that the corresponding feature and/or element is present, but excludes the presence or addition of one or more other features, elements, and/or groups thereof. It should be understood as not.

In addition, it will be understood that singular expressions such as “han” and “above”, which do not clearly indicate otherwise, include plural expressions.

In addition, terms including ordinal numbers such as first and second may be used to describe various elements, but the elements are not limited by the terms. These terms are used only for the purpose of distinguishing one component from another component. For example, without departing from the scope of the present invention, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element. The term and/or includes a combination of a plurality of related listed items or any of a plurality of related listed items.

In addition, terms used in the present specification are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as "comprise" or "have" are intended to designate the presence of features, numbers, steps, actions, components, parts, or a combination thereof described in the specification, but one or more other features. It is to be understood that the presence or addition of elements or numbers, steps, actions, components, parts, or combinations thereof, does not preclude in advance.

In addition, in the embodiments of the present invention, unless otherwise defined, all terms used herein including technical or scientific terms are commonly understood by those of ordinary skill in the art to which the present invention belongs. It has the same meaning as. Terms as defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and unless explicitly defined in the embodiments of the present invention, an ideal or excessively formal meaning Is not interpreted as.

1 is a diagram schematically showing a layered structure of an artificial light pain sensor according to an embodiment of the present invention.

Referring to Figure 1, the artificial light pain sensor according to an embodiment of the present invention is an FTO layer 100; An ATO layer 200 over the FTO layer; And a zinc oxide layer 300 on the ATO layer 200; It may include.

In an embodiment of the present invention, the FTO layer 100 is an FTO layer coated on a glass substrate, the ATO layer 200 includes ATO (Antimony doped Tin Oxide), and the zinc oxide layer 300 is It may contain zinc oxide (ZnO).

The ATO will thereby act as a material doped with antimony (Sb) on SnO _2, a donor by replacing the antimony (Sb) doped tin (Sn) of the tin oxide (SnO ₂₎ and increase the n-type conductivity.

In an embodiment of the present invention, the ATO layer 200 may have a thickness of 30 to 200 nm, and the zinc oxide layer 300 may have a thickness of 100 to 300 nm. More preferably, the ATO layer 200 may have a thickness of 50 to 150 nm, and the zinc oxide layer 300 may have a thickness of 150 to 250 nm. By having such a thickness, the ATO layer 200 and the zinc oxide layer 300 can operate as an artificial light pain sensor while maintaining transparency.

In an embodiment of the present invention, the FTO layer 100 is generated by coating FTO on a substrate, the ATO layer 200 is generated by depositing an ATO target by performing RF sputtering, and the zinc oxide layer is RF It may be generated by depositing a zinc oxide (ZnO) target by performing sputtering. After RF sputtering for depositing the ATO layer 200, rapid heat treatment may be performed.

2 is a diagram schematically showing an apparatus for manufacturing an artificial light pain sensor according to an embodiment of the present invention.

In the present invention, an ATO layer and a zinc oxide layer are grown on an FTO substrate using a joint sputtering device.

Specifically, the sputtering apparatus includes a chamber 1 having a substrate 9 mounted therein and receiving a ground voltage to an inner wall, and a sputter gun 3 located inside the chamber 1 and receiving a voltage 5 from the outside. , A magnet (2) located on the upper surface of the sputter gun (3), a target material (4) located on the lower surface of the sputter gun (3), a gun wall (6) for attaching and supporting the target material (4), the substrate (9) ), and a pump unit (not shown) for discharging the gas inside the chamber 1 to the outside.

Hereinafter, the operation of the manufacturing facility of the artificial light pain sensor of the present invention having the above configuration will be described.

First, a rare gas including argon gas or the like is injected into the chamber 1. After that, the injected argon gas is converted to the argon gas plasma 7 by causing gas discharge by the voltage 5 applied to the sputter gun 3. In this case, a magnetic field is formed in the chamber 1, that is, in the space between the target material 4 and the wafer 9 by the magnet 2 located on the upper surface of the sputter gun 3.

The argon gas plasma 7 generated by the gas discharge moves toward the target material 4 along the path of the magnetic field formed inside the chamber 1, thereby fixing the target material 4 on the key wall 6. ) Physically collide with the surface.

Accordingly, the deposition material 8 is released from the surface of the target material 4, and the deposition material 8 is deposited on the surface of the wafer 9 located on the lower surface of the chamber 1 To form a thin film.

A method of manufacturing an artificial light nociceptor according to an embodiment of the present invention using the artificial light nociceptor manufacturing facility shown in FIG. 2 is a substrate preparation process of coating FTO on a washed substrate (corresponding to 9), chamber 1 A first target material 4 containing ATO (tin oxide (SnO ₂ ):antimony oxide (Sb ₂ O ₃ ), 90:10 weight ratio) and an FTO-coated substrate (corresponding to 9) to be treated were placed in the , A first sputtering process in which a rare gas is introduced into the chamber 1 and an ATO layer is grown on the surface of the substrate by sputtering by applying power to the first target material, and zinc oxide (ZnO) in the chamber 1 By disposing a second target material 4 containing and a substrate (corresponding to 9) subjected to the first sputtering process, introducing a rare gas into the chamber 1, applying power to the second target material, and sputtering And a second sputtering process of growing a zinc oxide layer on the surface of the substrate.

Here, in the present invention, the heating unit 10 is disposed on the lower surface of the substrate 9 to heat the substrate to a predetermined temperature range during or after the sputtering process.

In this way, it is possible to stably form a layered structure having an ATO layer and a zinc oxide layer on the FTO coating substrate 9 in a single process. In one embodiment of the present invention, the FTO-coated substrate may have a sheet resistance of 6 to 8Ω/□.

Preferably, the first sputtering process corresponds to an RF sputtering process, and high-frequency power is applied to the first target material 4, and a magnetic field is formed on the opposite side of the substrate side of the first target material 4 Arrange a magnet member that can be used.

More preferably, the RF power applied to the first target material 4 in the first sputtering process corresponds to a range of 250 to 350W. In such a power range, the growth of the ATO can be stably achieved.

In addition, preferably, the second sputtering process corresponds to an RF sputtering process, a high frequency power is applied to the second target material 4, and a magnetic field is applied to the opposite side of the substrate side of the second target material 4 Arrange a magnet member that can be formed.

More preferably, the RF power applied to the second target material 4 in the second sputtering process corresponds to a range of 250 to 350W. In such a power range, the zinc oxide layer can be stably grown.

Preferably, the pressure in the chamber during the first sputtering process is maintained in the range of 3 to 10 mTorr. By maintaining the pressure range in the chamber, the ATO layer can be more stably formed and grown on the FTO-coated substrate. In this case, an argon gas environment having a flow rate of 40 to 60 sccm may be created in the chamber.

Also preferably, the pressure in the chamber during the second sputtering process is maintained in the range of 3 to 10 mTorr. By maintaining such a pressure range in the chamber, a zinc oxide layer can be more stably formed and grown on the substrate. In this case, an argon gas environment having a flow rate of 40 to 60 sccm may be created in the chamber.

In addition, in an embodiment of the present invention, the artificial light pain sensor may be subjected to heat treatment after generating the ATO layer. That is, the manufacturing method of the artificial light pain receptor may include a heat treatment process of performing heat treatment on the ATO layer formed through the first sputtering process as described above in a rapid heat treatment apparatus.

Preferably, the heat treatment may be performed at 450 to 550°C for 8 to 12 minutes.

In the present invention, the steps of arranging the FTO layer; Disposing an ATO layer on the FTO layer; And disposing a zinc oxide layer on the ATO layer. Including, it is possible to manufacture an artificial light pain receptor.

In more detail, as described above, a first target material including ATO and an FTO-coated substrate to be processed are disposed in the chamber, a rare gas is introduced into the chamber, and power is applied to the first target material, and the first target material is applied by sputtering. An ATO layer produced by a first sputtering process for growing an ATO layer on the FTO layer of a substrate, a second target material containing zinc oxide in the chamber, and a substrate subjected to the first sputtering process are disposed, and a rare gas is disposed in the chamber. Introducing, and applying electric power to the second target material, it is possible to manufacture an artificial light pain sensor including a zinc oxide layer manufactured by a second sputtering process in which a zinc oxide layer is grown on the surface of the substrate by sputtering. .

Hereinafter, characteristics of the artificial light pain sensor according to an embodiment of the present invention will be described.

3 is a diagram showing an SEM image of a zinc oxide layer of an artificial light pain sensor according to an embodiment of the present invention.

Referring to FIG. 3, a scanning electron microscope (SEM) plan view image of a zinc oxide layer 300 according to an embodiment of the present invention can be confirmed. The zinc oxide layer 300 according to an embodiment of the present invention may have a particle size of 20 to 30 nm. Such granular form may be characterized according to the manufacturing process of the zinc oxide layer 300.

4 is a diagram showing an XRD spectrum of an ATO layer of an artificial light pain sensor according to an embodiment of the present invention.

Referring to FIG. 4, results of performing X-ray diffraction (X-Ray Diffraction) for evaluating the crystal characteristics of the ATO layer 200 according to an embodiment of the present invention can be confirmed. Referring to Figure 4, there are strong peaks at 26.6°, 33.9°, 38.0° and 51.94°, which are (110), (101), (220) and (211) crystals of the tetragonal phase of the ATO layer. Each corresponds to a plane (JCPDS number 77-0448). For clarity, the crystal structure of the ATO layer 200 is shown in FIG. 5.

6 is a diagram showing the transmittance of an artificial light pain sensor according to an embodiment of the present invention.

The result of measuring the transmittance of oxides constituting the artificial light pain sensor according to an embodiment of the present invention is shown in FIG. 6. In the lower right of FIG. 6, a photograph of an artificial optical pain sensor actually manufactured according to an embodiment of the present invention is shown. 6, the artificial light pain sensor according to an embodiment of the present invention exhibits a transmittance of 65% or more in a visible light region (wavelength 400 to 700 nm). In the present invention, it is preferable that the artificial light pain receptor exhibits a transmittance of 50% or more in the visible light region.

7 is a diagram showing an absorbance and a photoluminescence spectrum of an ATO layer according to an embodiment of the present invention.

7 shows an absorbance spectrum and a photoluminescence spectrum of the ATO layer 200 of the present invention, respectively. As can be predicted from the transmittance spectrum of FIG. 6, the ATO layer 200 exhibited low absorbance in the visible light region. In addition, in the absorbance spectrum, long extended tails appearing up to 550 nm appear, which may be due to defect conditions in the gap, particularly oxygen vacancies.

To further clarify this, photo-luminescence (PL) measurement was performed. The photoluminescence spectrum showed an intense peak around 381 nm (about 3.25 eV) corresponding to the optical band gap of ATO.

In addition, the wide peak observed from 450 nm to 600 nm may generally be due to the presence of a trapped state inside the gap in wide bandgap oxides. These are mostly oxygen vacancies and are distributed in a conduction band of 0.84 eV or less. In general, oxygen vacancies transport and/or charge trapping/detrapping caused by such a defect state causes a resistive switching (RS) behavior in an oxide-based memristor as a primary factor.

8 is a diagram showing an SEM image of a layered cross-section of an artificial light pain sensor according to an embodiment of the present invention.

Referring to FIG. 8, a layered structure of an artificial light pain sensor according to an embodiment of the present invention can be confirmed.

In addition, SIMS (secondary ion mass spectrometry) measurement was performed to confirm the elemental distribution of the artificial light nociceptor.

9 is a diagram showing a concentration profile of an element according to a sputtering time in manufacturing an artificial light pain sensor according to an embodiment of the present invention. 9A and 9B illustrate element depth concentration profiles with respect to sputtering time in SIMS.

Referring to (a) of FIG. 9, the state of Sb ⁺ between the Zn ⁺ and Sn ⁺ matrices shows a sandwich of ATO.

In addition, the ratio of Zn+ is stably maintained from the surface to the sputtering time of 200 seconds, indicating that the zinc oxide layer 300 is uniformly formed. This ratio of Zn ⁺ starts to decrease when Sb ⁺ appears.

Further, as shown in (b) of FIG. 9, O ⁻ is uniformly distributed throughout, and does not show excessive change during the sputtering time.

As described above, according to the SIMS measurement result, the ATO layer 200 positioned between the zinc oxide layer 300 and the FTO layer 100 can be clearly identified.

10 is a diagram showing an element distribution of an artificial light pain sensor according to an embodiment of the present invention.

Energy-Dispersive X-ray Spectroscopy mapping was additionally performed to confirm the elemental distribution in the artificial light nociceptor according to an embodiment of the present invention.

Figure 10 (a) is a cross-sectional view of an artificial light pain receptor according to an embodiment of the present invention, Figure 10 (b) to (d) shows the distribution of each element of the artificial light pain receptor.

Referring to FIG. 10, not only such elements exist, but distribution in the artificial light pain receptor can be confirmed.

11 is a diagram showing a result of measuring I-V characteristics of an artificial light pain sensor according to an embodiment of the present invention.

Current-voltage (I-V) characteristics were measured in order to understand the charge transport of the artificial light pain sensor according to an embodiment of the present invention.

In (a) and (b) of FIG. 11, current-voltage characteristic curves obtained by repeatedly applying a voltage of 0V → 1V → 0V → -1V → 0V continuously for 5 cycles are shown in normal scale and half log scale, respectively. have.

In the case of positive bias, it can be seen that the forward (path (1)) and reverse (path (2)) scans do not follow the same path, and the current curve represents a hysteresis curve with an opening. In addition, as shown in (a) of FIG. 11, the current flowing through the artificial light pain sensor is gradually changed to show a different curve for each cycle.

On the other hand, a clear hysteresis curve does not appear in negative bias.

Such a hysteresis curve may appear due to the trapping/detrapping of charge and/or the movement of oxygen voids due to the influence of the applied bias.

12 is a diagram showing a result of measuring the retention of an artificial light pain sensor according to an embodiment of the present invention.

In FIG. 12, in order to confirm the shape of the hysteresis curve and the characteristics of the hysteresis curve as described above, the current generated when a pulse voltage is applied to the artificial light pain sensor is measured and shown. 12 shows characteristics when +1V and -1V pulses are sequentially applied at a read voltage of +0.6V.

Referring to FIG. 12, the current gradually increases from +1V, which is equal to or greater than 0.84V, which is a threshold value, and this is indicated by drinking in FIG. On the other hand, it gradually decreases at +0.6V below the threshold.

Also, the overall current at +1V increases gradually with every pulse. The cause of this is not clear, but may be due to the complex process of charge trapping/detrapping through oxygen voids and/or oxygen void transfer.

It was experimentally confirmed that such an increase in current is proportional to the area of the artificial light pain sensor. This indicates that the switching occurred in the entire region of the artificial light pain receptor, confirming that it was not influenced by local filament formation.

In fact, the RS of the artificial photonociceptor of the present invention is homogeneous and this is mainly due to charge trapping/detrapping.

In addition, in order to confirm that the state of charge trapping is related to oxygen deficiency, the artificial light pain sensor of the present invention was annealed in an oxygen environment at 500°C. It was confirmed that the opening of the hysteresis curve was significantly reduced in the I-V curve measured for the artificial light pain receptor after annealing.

13 is a diagram showing a result of measuring I-V characteristics of an artificial light pain sensor according to an embodiment of the present invention.

The charge dynamics in the artificial photonociceptor according to an embodiment of the present invention can be confirmed by performing fitting to the I-V curve. In Fig. 13, the I-V curve of the artificial light pain receptor is plotted on a log scale.

Referring to FIG. 13, the I-V curve is composed of three regions. In the low bias (0 to 0.23V) region, resistance characteristics (I∝V) are exhibited by heat-generating free carriers.

-

곡선은 약 1.88의 멱수를 보인다. 이와 같이 2 보다 작은 값을 갖는 것은 산화아연층(300) 및 ATO층(200)의 계면에서의 전하 캐리어의 트래핑 또는 산소 공극의 이동에 의한 것으로 추정된다.On the other hand, in the high bias region, the current changes nonlinearly as in the Child's Law (I∝V ² ) region, and at this time, the trap is filled by the injected electrons. In this bias range

-

The curve has a power of about 1.88. It is estimated that the value of less than 2 is due to trapping of charge carriers or movement of oxygen voids at the interface between the zinc oxide layer 300 and the ATO layer 200.

The last area is a trap charging area in which a threshold voltage (V _TFL ) in which the current rapidly increases is present. The threshold voltage (V _TFL ) of the artificial light pain sensor according to an embodiment of the present invention is about 0.75V. Therefore, the opening of the hysteresis curve can be explained by the trap control space charge limit current (SCLC) mechanism in which the oxygen void serves as an electron trap.

14 is a diagram schematically showing a charge transport mechanism of an ATO layer according to an embodiment of the present invention.

The artificial light pain sensor according to an embodiment of the present invention traps electrons by including oxygen voids in the ATO conduction band as shown in FIG. 14. These traps are gradually filled with electrons injected from the electrode.

14A shows the behavior in a region below the threshold voltage V _TFL .

In addition, in (b) of FIG. 14, as the applied voltage gradually increases, all traps are filled and the current rapidly increases.

In addition, FIG. 14C shows a state in which the device returns to its original state due to the occurrence of detrapping of the oxygen voids while the opposite voltage is applied.

15 and 16 are diagrams illustrating an optical response to an optical pulse input of an artificial optical pain sensor according to an embodiment of the present invention.

FIG. 15 shows the result of measuring the light response when a 1 Hz ultraviolet (365 nm, 15.5 mW/cm ² ) light pulse is applied to the artificial light pain sensor without an applied voltage. Referring to FIG. 15, it can be seen that the magnitude of the photocurrent generated by the ultraviolet pulse increases with each pulse.

In order to confirm this more clearly, the result of measuring the light response to the continuous light pulse is shown in FIG. 16.

As indicated by the dotted line in FIG. 16, it can be seen that not only the photocurrent but also the dark current gradually increases as the pulse is repeated. This confirms that the photogenerated electron-hole pairs fill the trap and produce relatively smooth conduction.

In addition, the current flowing through the artificial light pain sensor reaches a saturation state, indicating that it can be used as a light reactive pain sensor. However, it is necessary to satisfy important characteristics of nociceptors such as threshold, no adaptation, and relaxation due to allodynia and hyperalgesia.

17 is a diagram illustrating a light response according to a stimulation intensity of an artificial light pain sensor according to an embodiment of the present invention.

17 shows the results of measuring the light response under self-bias conditions to confirm the critical characteristics of the artificial light pain receptor.

In FIG. 17, the light response was measured while changing the intensity of ultraviolet rays from 2 to 13.44 mW/cm ² . Referring to FIG. 17A, it can be seen that the artificial light pain sensor according to an embodiment of the present invention does not exhibit a remarkable light response at an ultraviolet intensity of 9.5 mW/cm ² or less. However, at an ultraviolet intensity of 9.5 mW/cm ² or more, the light response is exhibited, and it can be seen that the size increases as the ultraviolet intensity increases.

These results indicate that sufficient light-induced electron-hole pairs must be generated in order for charge transport to occur in the self-bias condition, whereby the artificial light pain receptor responds to light stimulation below the threshold value and light stimulation above the threshold value. It has a threshold characteristic representing a different light response.

FIG. 17(b) shows an enlarged view of the optical response corresponding to point 1 of FIG. 17(a), and FIG. 17(c) shows the optical response corresponding to point 2 of FIG. 17(a). An enlarged view of is shown. When comparing (b) of FIG. 17 and (c) of FIG. 17, the difference between the optical response at a stimulus below the threshold and a stimulus above the threshold can be clearly confirmed. This threshold characteristic is the main characteristic of the nociceptor, indicating that the artificial optical nociceptor of the present invention can function as a nociceptor.

18 is a diagram illustrating a light response to an input of an ultraviolet pulse of an artificial light pain sensor according to an embodiment of the present invention.

FIG. 18(a) shows a light response to a sequential ultraviolet pulse (12.4 mW/cm ² ) to an artificial light pain sensor according to an embodiment of the present invention. Referring to (a) of FIG. 18, the photocurrent due to the ultraviolet pulse gradually increases and is saturated.

After reaching the saturation state, the value of the photocurrent does not change even when a continuous ultraviolet pulse is applied, indicating that the photoresponse does not change even for repeated inputs of the same stimulus. This phenomenon appears as an equilibrium occurs between the generation and trapping of photogenerated electron-hole pairs.

Such a phenomenon is similar to a characteristic of no adaptation in which the response does not change even to repeated inputs of the same stimulus of the pain sensor, and the non-adaptation characteristic is a very important characteristic of protecting the human body against repeated harmful stimuli.

In addition, as shown in (b) of FIG. 18, when the artificial light pain sensor escapes from the ultraviolet pulse stimulation, it is alleviated to the dark current level at the initial stage of the photoreaction within 30 ms. As described above, the artificial optical nociceptor according to an embodiment of the present invention exhibits similar characteristics to the relaxation characteristics of the nociceptor.

19 is a diagram showing a light response according to an intensity of an ultraviolet pulse of an artificial light pain sensor according to an embodiment of the present invention.

In order to confirm the dynamic behavior of the artificial light nociceptor according to an embodiment of the present invention in more detail, light responses were measured for different UV intensities of 9.5 mW/cm ² , 19.4 mW/cm ² and 26.5 mW/cm ² . , The measured results are shown in FIG. 19. (A), (b) and (c) of FIG. 19 show the light responses to the ultraviolet intensity of 9.5 mW/cm ² , 19.4 mW/cm ² and 26.5 mW/cm ² , respectively. At the top of each figure, the UV pulse applied in each photoresponse measurement is shown.

Referring to (a) of FIG. 19, at an ultraviolet intensity of 9.5 mW/cm ² , the artificial light pain receptor does not immediately react to an ultraviolet pulse. However, in the artificial light pain sensor, a photocurrent appears after a little time (0.2 seconds) as shown in the lower part of FIG. 19A. The time at which the photocurrent starts to appear in response to such an ultraviolet stimulus can be defined as a reaction time (t _s ).

As shown in (b) of FIG. 19, when the ultraviolet intensity increases to 19.4 mW/cm ² , t _s decreases to 0.06 seconds. Further, as can be seen in (c) of FIG. 19, t _s gradually decreases as the ultraviolet intensity increases.

FIG. 20 is a diagram showing a light response according to the intensity of an ultraviolet pulse of an artificial light pain sensor according to an embodiment of the present invention, and FIG. 21 is an intensity of the ultraviolet pulse of the artificial light pain sensor according to an embodiment of the present invention. It is a diagram showing the reaction time according to.

In FIG. 20, the light responses appearing according to various intensities of ultraviolet pulses as in FIG. 19 are also shown. As shown in FIG. 20, it can be seen that as the ultraviolet intensity increases, not only the magnitude of the photoresponse of the artificial light pain sensor increases, but also the response time t _s decreases.

In order to confirm this relationship, the reaction time according to the UV intensity is shown in FIG. 21.

When sequential ultraviolet pulses are irradiated, the artificial light nociceptor generates sufficient electron-hole pairs and, as a result, saturates the trap state, thereby changing the pattern of the light response. In addition, the higher the ultraviolet intensity, the relatively more electron-hole pairs are generated, so that the reaction time (t _s ) decreases.

22 is a diagram showing a light response according to a frequency of an ultraviolet pulse of an artificial light pain sensor according to an embodiment of the present invention.

Figure 22 shows the photoresponse of the artificial light pain receptor under ultraviolet (17.2 mW/cm ² ) illumination of three different pulse frequencies (35 Hz, 300 Hz and 1 kHz). As described above, referring to FIG. 22, it can be seen that the artificial light pain sensor exhibits non-adaptive characteristics, and it can be seen that the optical response is also greatly affected by the pulse frequency.

The threshold and non-adaptation characteristics of the artificial optical pain sensor according to an embodiment of the present invention are very similar to that of the human body, and in particular, the artificial optical pain sensor according to an embodiment of the present invention has a millisecond unit of 300 ms or less. It has a reaction time of (t _s ), which is similar to that of the nociceptor signal of the human body.

23 is a diagram showing the characteristics of a pain sensor of an artificial light pain receptor according to an embodiment of the present invention.

The human body's nociceptor exhibits allodynia and hyperalgesia characteristics as shown in FIG. 23(a). When damaged, the nociceptor responds more rapidly at lower thresholds. This is a phenomenon as shown by the horizontal and vertical arrows in Fig. 23(a), and the phenomenon that the threshold value is lowered by strong light stimulation such as horizontal arrows is amplified by the light response by strong light stimulation such as allodynia and vertical arrows. This phenomenon is called hyperalgesia.

The photonociceptor is not damaged by weak ultraviolet rays (L _UV ), but is damaged by strong ultraviolet rays (H _UV ). 23(b) shows the light response to weak ultraviolet (L _UV ), and the light response of the artificial light pain sensor in the non-damaged state before irradiation with strong ultraviolet (H _UV ) is a black line, strong The photoresponse of the artificial light nociceptor in a damaged state after irradiation with ultraviolet (HUV) is shown as a red line.

The artificial light pain receptor before irradiation with strong ultraviolet (H _UV ) has a low photocurrent value for weak ultraviolet (L _UV ). On the other hand, the artificial light pain receptor damaged after intense ultraviolet (H _UV ) irradiation exhibited amplified photocurrent values even for similar low ultraviolet (L _UV ) intensity. This indicates that the trap is filled by the intense ultraviolet (H _UV ) irradiation, thereby exhibiting a fast light response, lowering the threshold, and enhancing the response of the nociceptor.

That is, strong ultraviolet (H _UV ) lowers the threshold of the artificial light pain sensor to exhibit allodynia, and amplifies the photoreaction of the artificial light pain receptor to exhibit hyperalgesia.

24 is a view comparing the mechanism of operation of the artificial light pain sensor and the mechanism of operation of the human eye according to an embodiment of the present invention.

As shown in FIG. 24, it can be seen that the artificial optical nociceptor according to an embodiment of the present invention exhibits a reaction similar to that of the human eye. The human body has various sensory nerves that respond to external signals and produces biochemical signals based on signal strength, duration, and repetition. When a signal reaches the nociceptor, it works in two ways, depending on the strength of the signal. Nociceptors function normally if the signals are not harmful, but respond stronger and faster to harmful signals. In addition, after the noxious signal is removed, the nociceptor is alleviated within a short period of time and is ready to receive another signal again.

The eye is one of the most important parts of the human body, and if the intensity of incoming light is too strong while the eye reacts normally to incident light, the eyelids are automatically closed to protect the eye. Similarly, the artificial light pain sensor according to an embodiment of the present invention accepts external optical stimuli such as the human eye and modulates its behavior using a stimulus threshold to determine the output of the response. If the stimulus is weaker than the threshold, the artificial light pain receptor does not generate an electrical signal, but if it is above the threshold, it also exhibits "threshold", "non-adaptation" and "mitigating" properties for incoming light. As described above, the artificial light nociceptor according to an embodiment of the present invention has a simple structure and may perform the same role as the nociceptor.

According to an embodiment of the present invention, it is possible to provide a transparent artificial light pain sensor capable of detecting damage caused by light.

According to an embodiment of the present invention, it is possible to provide an artificial light pain sensor having a threshold characteristic for light stimulation.

According to an embodiment of the present invention, it is possible to provide an artificial light pain sensor having non-adaptation characteristics to light stimulation.

According to an embodiment of the present invention, it is possible to provide an artificial light pain sensor having allodynia and hyperalgesia properties to light stimulation.

The description of the presented embodiments is provided to enable any person skilled in the art to use or implement the present invention. Various modifications to these embodiments will be apparent to those of ordinary skill in the art, and the general principles defined herein can be applied to other embodiments without departing from the scope of the present invention. Thus, the present invention is not to be limited to the embodiments presented herein, but is to be interpreted in the widest scope consistent with the principles and novel features presented herein.

Claims (10)

As an artificial light nociceptor,
FTO layer;
An ATO layer over the FTO layer; And
A zinc oxide layer on the ATO layer; Including,
The ATO layer contains oxygen voids, artificial light pain receptor.
The method according to claim 1,
The artificial light pain receptor,
A threshold characteristic indicating a different optical response to a light stimulus less than a threshold value and a light stimulus above the threshold value;
Non-adaptation characteristic in which the response does not change even for repeated input of the same stimulus;
Allodynia in which the threshold is lowered by strong light stimulation; And
Hyperalgesia in which the light response is amplified by strong light stimulation; Representing, artificial light pain receptor.
The method according to claim 1,
The ATO layer,
An artificial light pain sensor that is created by depositing an ATO target by performing sputtering.
The method of claim 3,
The ATO layer,
After sputtering, the artificial light nociceptor to perform rapid heat treatment.
The method according to claim 1,
The zinc oxide layer,
An artificial optical pain sensor that is created by depositing a zinc oxide target by performing sputtering.
The method according to claim 1,
The ATO layer has a thickness of 30 to 200 nm,
The zinc oxide layer has a thickness of 100 to 300nm, artificial light pain sensor.
The method according to claim 1,
The artificial light pain receptor,
An artificial light pain sensor having a transmittance of 50% or more in a visible light region (wavelength 400 to 700 nm).
As a method of manufacturing an artificial light pain receptor,
Arranging an FTO layer;
Disposing an ATO layer on the FTO layer; And
Disposing a zinc oxide layer on the ATO layer; Including,
The ATO layer includes oxygen voids, the method of manufacturing an artificial light pain sensor.
The method of claim 8,
The artificial light pain receptor,
A threshold characteristic indicating a different optical response to a light stimulus less than a threshold value and a light stimulus above the threshold value;
Non-adaptation characteristic in which the response does not change even for repeated input of the same stimulus;
Allodynia in which the threshold is lowered by strong light stimulation; And
Hyperalgesia in which the light response is amplified by strong light stimulation; Representing, the manufacturing method of the artificial light pain receptor.
The method of claim 8,
The ATO layer,
A method of manufacturing an artificial light pain sensor that is generated by performing sputtering to deposit an ATO target.

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