JP2793403B2 - Chemical substance recognition method, recognition information storage method, and chemical substance sensing system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of recognizing a chemical substance which can recognize a wide variety of chemical substances and which imitates the taste and smell of living organisms, a method of storing information for verification used in the recognition, and The present invention relates to a chemical substance sensing system suitable for implementing these recognition methods and storage methods.

[0002]

BACKGROUND OF THE INVENTION Generally, taste and smell arise from a complex and comprehensive combination of a wide variety of chemicals. Then, organisms recognize such tastes and smells by taste and smell. However, there are still many unclear points about the mechanism of taste and smell. However, when recognizing taste and smell,
The response of the recipient cells of the organism is non-specific for each chemical substance, but information about each chemical substance is converted into an oscillation pattern of a nerve impulse with a lot of information, which is recognized in the brain by pattern recognition It is believed that.

On the other hand, demands for artificially recognizing tastes and smells are extremely high in various fields such as the food industry, the cosmetics industry, the environmental measurement field, and the like. Therefore, research on this type of recognition method has been conventionally performed.

[0004] As one of the methods, there has been a method of converting information on a chemical substance into an analog quantity such as electric conductivity and recognizing the chemical substance based on the analog quantity.

As another method, for example, as disclosed in the literature (IEICE Technical Report MBE88-78, p. 41), the taste and smell are recognized by using a quartz oscillator sensor array and a neural network. There was a way to try. This method utilizes the fact that the frequency of a crystal oscillator changes when a chemical substance is adsorbed on a crystal oscillator sensor, which is formed by applying an adsorption film on a crystal oscillator in advance. It was intended to convert it into a change in the frequency of the vibrator and to perform pattern recognition using a neural network. For this reason, this method can be said to be a recognition method quite similar to taste and smell.

[0006]

However, in the former method of converting information on a chemical substance into an analog quantity such as electric conductivity, among the conventional methods, it is necessary to recognize various chemical substances in order to recognize various chemical substances. However, there is a problem that a large number of receptors specifically responding to the above chemical substances are required.

In the case of a method using a quartz oscillator sensor array as the receiving portion, a chemical substance that does not physically adsorb to the adsorption film applied to the quartz oscillator cannot be recognized, so that there is a limit to the recognizable chemical substance. Further, there is a problem that the information amount is small because only the change in the frequency of the crystal unit is used as the recognition information. Furthermore, as in the former technique, in order to recognize a wide variety of chemical substances, a large number of receiving parts (for example, multiple quartz crystal sensors with different types of adsorption films) that respond to those chemical substances are required. There has been a problem that the configuration of the recognition device is complicated, and in some cases, recognition is difficult due to a lack of an appropriate adsorption film.

The present application has been made in view of the above points, and therefore, an object of the first invention of the present application is to provide a recognition method capable of recognizing taste and smell in a manner similar to taste and smell than before. It is in. Another object of the second invention of this application is to provide a method of storing information for verification used for recognition in the recognition method of the first invention. Another object of the third invention of the present application is to provide a sensing system suitable for implementing the first and second inventions.

[0009]

In order to achieve this object, the inventor of the present application has conducted various studies. And (a). Freeman's findings in the rabbit olfactory bulb (the part that processes odor information in the brain) (Reference a)
("Biological Cyd
ernetics) ", disclosed in Springer-Verlag (1987), pp. 139-150) and (b). In an artificial membrane (excitable artificial membrane) in which a certain kind of lipid is adsorbed on a porous membrane, even though electrical chaos oscillation may occur under certain conditions, the oscillation pattern changes in response to various chemical substances. It becomes clear by calculating the correlation dimension (Jpn. J. Appl. Phys., Vol. 28, No. 8
(1989), p.1507-1512). Here, the findings obtained by Freeman are that when the electrodes are chronically implanted in the olfactory bulb of rabbits and the collective action potential of this olfactory bulb for various odor stimuli is measured, it is the first time that the action potential for Is chaotic, but if the rabbit is reminded of various odors and then re-applied to the rabbit again, the action potential becomes a limit cycle (periodic orbit). That is, the finding is that different odors correspond to limit cycles having different amplitudes and periods.

[0010]

Further, according to the study of the inventor of the present application, in addition to applying a direct current to the excitable artificial membrane, when an alternating current is further applied to optimize the amplitude and frequency of the alternating current, the excitability is increased. The periodicity of the chaotic oscillation in the artificial membrane became apparent, and the complexity of the attractor of the chaotic oscillation decreased, and it was found that the cycle approached the limit cycle.
Such a phenomenon is known as a pull-in phenomenon of a nonlinear oscillator, but was also confirmed in an excitable artificial membrane. It was also found that the amplitude and frequency of the alternating current that can change the chaotic oscillation into a limit cycle are unique for each chemical substance.

Therefore, according to the first invention of this application, a chemical substance is recognized based on chaotic oscillation caused by the chemical substance in an excitable artificial membrane in a state where an alternating current is superimposed on a direct current. In the method, at least one information of an amplitude and a frequency of the alternating current that changes the chaotic oscillation into a limit cycle and a shape of an attractor in the limit cycle state is obtained and stored in advance for each chemical substance. Then, information corresponding to the stored information is obtained for the chemical substance to be recognized. And
By comparing the obtained information with the stored information, the chemical substance to be recognized is recognized.

According to the chemical substance recognition information storage method of the second invention of the present application, chaotic oscillation caused by a chemical substance occurs in an excitable artificial membrane in a state where a current obtained by superimposing an alternating current on a direct current is applied. As information for verification for recognizing a chemical substance based on the amplitude of the alternating current that changes the chaotic oscillation into a limit cycle, at least one information of the frequency and the shape of the attractor in the limit cycle state, It is characterized in that it is stored in advance.

[0014]

Further, according to the chemical substance sensing system of the third invention of this application, a receiving portion composed of an excitable artificial membrane that generates an electric chaotic oscillation, and an alternating current to a direct current is applied to the excitable artificial membrane. A current source for applying a superimposed current; and an amplitude, frequency and the limit cycle state of the AC current for changing a chaotic oscillation caused by a chemical substance into a limit cycle in the excitable artificial membrane in a state where the current is applied. An information processing unit for measuring at least one of the shapes of the attractors in the above, a storage unit for storing the measured information, and information stored in the storage unit and a chemical substance to be recognized corresponding to the information. And an information processing section having a recognition section for recognizing the chemical substance by comparing the information with the information.

[0016]

[0017]

According to the structure of the first invention, the following effects can be obtained. The amplitude, frequency and attractor shape of the alternating current that changes chaotic oscillation caused by a chemical substance into a limit cycle in an excitable artificial membrane applied with a current obtained by superimposing an alternating current on a direct current are: Both values and shapes are peculiar to the chemical substance as compared with the amplitude, frequency and shape of the attractor in the state of simple chaotic oscillation other than the limit cycle state. Therefore, even if the chemical substance does not show a difference in the shape of the attractor of simple chaotic oscillation that is not in the limit cycle state, if attention is paid to at least one of the amplitude, frequency, and shape of the attractor of the AC signal in the limit cycle state, Can be identified as a chemical substance. Further, more precise identification can be performed by using information of two or more of the amplitude, the frequency, and the shape of the attractor. Further, when the chemical substance is identified using the amplitude and / or the frequency, the memory capacity of the storage unit can be reduced as compared with the case where the shape of the attractor is used,
Further, the storage unit can store a large amount of reference information on chemical substances.

Further, according to the configuration of the second invention, it is possible to appropriately store the recognition information for reference in implementing the first invention.

Further, according to the configuration of the third invention of this application, industrial implementation of the first and second inventions is facilitated.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of each invention of this application will be described below with reference to the drawings. The drawings used in the description schematically show the dimensions, shapes and arrangements of the components so that the present invention can be understood. In addition, the materials used and the concentrations of the materials used in the following description, the voltage value during the experiment,
Numerical conditions such as current value, time, and the like are merely examples within the scope of the present invention.

1. Preparation of Excitable Artificial Membrane The excitable artificial membrane relating to each of the first to third inventions is a synthetic lipid dioleyl phosphate represented by the following formula (1) (hereinafter abbreviated as “DOPH”) in this embodiment. Is adsorbed on a porous membrane. Specifically, a DO prepared by dissolving a predetermined amount of DOPH in benzene
A millipore filter (a filter manufactured by Millipore) having a large number of pores having a pore size of 5 μm is immersed in a PH-benzene solution, and then the millipore filter is taken out from the solution and benzene is evaporated to produce an excitable artificial membrane. . The amount of DOPH adsorbed on the millipore filter is set so that self-excited oscillation is easily generated in the excitable artificial membrane.

[0022]

Embedded image

2. Description of Sensing System Further, as a chemical substance sensing system according to the third invention suitable for carrying out the first invention and the second invention, a system as described below is prepared in this embodiment. FIG. 1 is a block diagram for the explanation.

The sensing system of this embodiment has a first
To fourth tanks 11 to 14, a current source having a DC current source 15a and an AC current source 15b, an information processing unit 16, an XY
And a recorder 17.

Holes 11a and 12a each having a diameter of 5 mm are formed in a part of each of the first tank 11 and the second tank 12. These first and second tanks 11 and 12
By sandwiching the excitable artificial membrane 21 produced as described above between the hole forming surfaces, the excitable artificial membrane 21 is set in this system. In each of the first tank 11 and the second tank 12, an electrolyte solution that causes chaotic oscillation easily in the excitable artificial membrane 21 is put. In this embodiment, a 1 mM KCl aqueous solution is placed in both tanks 11 and 12, respectively. These KCl aqueous solutions come into contact with the excitable artificial membrane 21 at the holes 11a and 12a of both the tanks 11 and 12, respectively.

The third tank 13 is connected to the first tank 11 via a salt bridge (Salt Bridge) 18a, and the fourth tank 14 is connected to the second tank 12 and a salt bridge. 18b. Each of the third and fourth tanks 13 and 14 contains a saturated electrolyte solution, in this case, a 3M KCl aqueous solution.

The current source 15 is for applying one or both of a DC current and an AC current to the excitable artificial membrane 21. In this case, only the DC current, only the AC current, or the AC current is superimposed on the DC current. Current (this is also considered as an alternating current, but may be hereinafter referred to as “superimposed current”).
Is applied as required. The application of the current from the current source 15 to the excitable artificial membrane 21 is performed by connecting the one current application electrode 1 connected to one output terminal of the current source 15 and immersed in the third tank 13.
9a (for example, Ag-AgCl electrode) and the other current application electrode 19b (for example, Ag-AgC electrode) connected to the other output terminal of the current source 15 and immersed in the fourth tank.
1 electrode).

Further, the information processing section 16 of this embodiment measures and stores the shape of the attractor of the chaotic oscillation generated in the excitable artificial membrane 21 and the amplitude and frequency of the alternating current that can use the chaotic oscillation as a limit cycle. Further, as information for verification for recognizing a chemical substance, (1). Shape of attractor in chaotic oscillation when DC current is applied to excitable artificial membrane 21, (2). (3) amplitude of an alternating current that can be used as a limit cycle with chaotic oscillation when an alternating current (including a superimposed current) is applied to the excitable artificial membrane 21; The frequency of this alternating current, and (4). A storage unit (not shown) for storing at least one of the four pieces of information of the shape of the attractor in the limit cycle state, and information stored in the storage unit and corresponding information measured at the time of sensing. And a recognition unit (not shown) for recognizing and recognizing a chemical substance. In this case, the input of the electric chaos oscillation generated in the excitable artificial membrane 21 to the information processing unit 16 is performed in the third tank 1 in this case.
The measurement electrode 20a (for example, Ag-A
The change in potential detected by the gCl electrode) and the measurement electrode 20b (for example, an Ag-AgCl electrode) immersed in the fourth tank 14 is taken in through the amplifier 20c.

Such an information processing unit 16 includes, for example, A /
Although it can be configured using a conventionally known electric circuit technology such as a D conversion circuit, a sampling circuit, a comparison circuit, and a memory, it is simple and suitable to configure it with a computer.

In the chemical substance sensing system shown in FIG. 1 configured as described above, by adding a known chemical substance into the first tank 11 and the second tank 12, the excitability caused by the chemical substance is added. Chaotic oscillation of the artificial membrane 21 can be generated, and reference information based on the shape of the attractor of the chaotic oscillation can be stored in a storage unit (not shown) of the information processing unit 16. In addition, the first tank 11 and the second tank 11
Chaos oscillation of the excitable artificial membrane 21 caused by the chemical substance can be caused by adding an unknown chemical substance into the tank 12 of the above, and information based on the shape of the attractor of the chaotic oscillation can be obtained. This unknown chemical substance can be recognized by comparing this information with the above-mentioned reference information (the details will be described later).

The electrodes 19a and 20a are immersed in the first tank 11 without providing the third and fourth tanks 13 and 14, and the electrodes 19b and 20b are immersed in the second tank 12, respectively. Even in principle, however, it is possible to recognize chemical substances.

3. Next, an example of recognition of a chemical substance will be described.

Using a current source 15 of the system shown in FIG. 1, a current obtained by superimposing an alternating current having an amplitude of 0.2 μA and a frequency of 0.5 Hz on a direct current of 0.5 μA is applied to the excitable artificial membrane 2.
Apply to 1. Then, under such current application conditions, the potentials observed at the measurement electrodes 20a and 20b are taken into the information processing unit 16 over time and recorded by the XY recorder 17. As a result, as shown in FIG. 2, an oscillation waveform that fluctuated in potential was recorded on the XY recorder 17.

Next, in the oscillation waveform obtained in this way, the potential of the superimposed current applied to the artificial membrane 21 is a local maximum value, in this case, 0.1 + 0.5 = 0.6 μA. taken sequentially sampled and these values Lorenz plot (n-th sampling potential V _n X coordinate for each local maximum corresponding time n + 1 th sampling potential V
These are plotted sequentially with _{n + 1} as the Y coordinate. For example, literature: Biophysics, Vol. 23, no. 6, p. 2
3 (1983). 2), an attractor for chaotic oscillation in the excitable artificial membrane 21 in a state where no chemical substance is added is obtained. The attractor was as shown in FIG.

Next, a predetermined amount of coffee manufactured by Company A is added to each of the first tank 11 and the second tank 12 as a chemical substance. Then, the information processing unit 16 captures the chaotic oscillation generated in the excitable artificial membrane 21 at this time. Next, a Lorentz plot is made from the oscillation waveform obtained here (as shown in FIG. 2; however, the waveform is different from that in FIG. 2 due to the addition of coffee) in the same manner as the above-described procedure when no chemical substance is added. Excitable artificial membrane 21 caused by coffee manufactured by Company A
Get the attractor of chaotic oscillation caused by. The attractor was as shown in FIG.

When the chemical substance to be added to each of the first tank 11 and the second tank 12 is orange flavor, apple flavor, or coffee manufactured by Company B, attractors are obtained by the above-described procedure. The attractor caused by orange taste and the attractor caused by apple taste are shown in FIGS. 5 and 6, respectively.

As is clear from the results shown in FIGS. 3 to 6, the shape of the attractor of the oscillation caused by the chemical substance of the excitable artificial membrane 21 depends on the type of the chemical substance (including the case without addition), that is, the taste. It can be seen that it differs depending on the type of. For this reason, the shape of the attractor of oscillation caused by various tastes is stored in advance in a storage unit (not shown) of the information processing unit 16 as reference information, and an unknown chemical substance (a substance having a certain taste) is stored therein. It can be understood that this chemical substance (this taste substance) can be recognized by collating the attractors obtained from (1). However, for the similar tastes, for example, in the above-mentioned example, the shapes of the attractors of the chaos oscillation under the above-described superimposed current conditions were similar between the coffee manufactured by the company A and the coffee manufactured by the company B. Could not.

Then, next, when the coffee made by the company A and the coffee made by the company B are added to the first tank 11 and the second tank 12, respectively, the superposition applied to the excitable artificial membrane 21 is added. The amplitude and frequency of the alternating current among the currents are variously changed, the attractor under each alternating current condition is examined, and the amplitude and frequency of the alternating current at which the attractor shape comes closest to the limit cycle are measured. Attractors close to the limit cycle found in this way are shown in FIG. 7 for coffee manufactured by Company A and in FIG. 8 for coffee manufactured by Company B.

As is apparent from a comparison of FIGS. 7 and 8, when attractors close to the limit cycle are used as recognition information, the shapes of the attractors of the two attractors are greatly different. It can be seen that it is possible to identify the coffee manufactured by Company B and the company B. In addition, the amplitude of the alternating current at which an attractor close to the limit cycle can be obtained is 0.075 μm in the case of coffee added by Company A.
A has a frequency of 0.8 Hz, and in the case of coffee added by Company B, the amplitude is 0.085 μA and the frequency is 0.7.
Since the two are slightly different from each other, such as those at Hz, more precise discrimination can be performed by using the AC current and the shape of the limit cycle as recognition information.

Further, it was found that the amplitude and frequency of the alternating current that brings the attractor closer to the limit cycle were considerably different for tastes that were significantly different from each other. For example, as described above, the alternating current when coffee manufactured by Company A is added has an amplitude of 0.075 μA and a frequency of 0.8H.
z, when orange flavor is added, the amplitude is 0.06 μA and the frequency is 0.4 Hz, and when apple flavor is added, the amplitude is 0.14 μA and the frequency is 1.5 Hz. Became different from each other. Therefore, for tastes that are quite different, even if only the amplitude and frequency of the alternating current that brings the attractor closer to the limit cycle are used as recognition information, each taste (each chemical substance)
Can be understood. In such a configuration in which the chemical substance is recognized based on the amplitude and frequency of the alternating current, the reference information stored in the information processing unit 16 can be determined only by the amplitude and frequency of the alternating current. This is useful because the capacity can be reduced and a large amount of information on chemical substances can be stored.

In the above, the embodiments of each invention of this application have been described, but these inventions are not limited to the above embodiments.

For example, in the above-described embodiment, the attractor of chaotic oscillation is obtained by Lorentz plot, but the attractor may be obtained by another method as long as the object of the present invention can be achieved.

The structure of the excitable artificial membrane described above is merely an example, and the method of producing the lipid, the porous membrane, and the artificial membrane to be used can be changed to other suitable materials and methods.

[0044]

As is apparent from the above description, according to the first invention of this application, the excitable artificial membrane in the state where the current obtained by superimposing the alternating current on the direct current is caused by the chemical substance. In a method of recognizing a chemical substance based on chaos oscillation, at least one information of an amplitude, a frequency, and a shape of an attractor in the limit cycle state for changing the chaos oscillation into a limit cycle is obtained. Is obtained in advance and collated with information on various chemical substances to recognize the chemical substances. These amplitudes,
Each of the frequency and the shape of the attractor has a value and a shape specific to the chemical substance as compared with the amplitude, the frequency and the shape of the attractor in a state of simple chaotic oscillation other than the limit cycle state. Therefore,
Recognize chemical substances in a manner similar to taste and smell. Further, when a chemical substance is identified using two or more pieces of information among the amplitude, frequency, and attractor shape, the chemical substance can be identified more precisely. Further, when a chemical substance is identified using the amplitude and / or the frequency, the memory capacity of the storage unit can be reduced as compared with the case where the shape of the attractor is used, and more information of the chemical substance is stored in the storage unit. Can be stored.

Further, according to the recognition information storing method of the second invention of this application, the recognition information for reference in implementing the first invention can be stored properly.

Further, according to the chemical substance sensing system of the third invention of this application, industrial implementation of the first and second inventions is facilitated.

[0047]

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a sensing system used for implementing first to third inventions.

FIG. 2 is an explanatory diagram of a procedure for obtaining an attractor for chaotic oscillation of an excitable artificial membrane.

FIG. 3 is a diagram provided for explaining an example, and is a diagram showing an attractor in a case where no chemical substance is added.

FIG. 4 is a diagram provided for explaining the embodiment, and is a diagram showing an attractor in the case of adding coffee manufactured by Company A.

FIG. 5 is a diagram provided for explanation of an example, and is a diagram showing an attractor in the case of adding orange flavor.

FIG. 6 is a diagram provided for describing an example, and is a diagram showing an attractor in the case of adding apple flavor.

FIG. 7 is a diagram provided for explaining the example, and is a diagram showing a limit cycle of the attractor in the case of adding coffee manufactured by Company A.

FIG. 8 is a diagram provided for explaining the example, and is a diagram showing a limit cycle of the attractor in the case of adding coffee manufactured by Company B.

[Explanation of symbols]

11: First tank (for example, in 1 mM KCl aqueous solution) 11a: Hole 12: Second tank (for example, in 1 mM KCl aqueous solution) 12a: Hole 13: Third tank (for example, in 3M KCl aqueous solution) 14: No. Tank 4 (for example, in a 3M KCl aqueous solution) 15: Current source 15a: DC current source 15b: AC current source 16: Information processing unit 17: XY recorder 18a, 18b: Salt bridge 19a, 19b: For applying current Electrodes (eg, Ag-AgC
1 electrode) 20a, 20b: electrode for measurement (eg, Ag-AgCl electrode) 21: excitable artificial membrane

──────────────────────────────────────────────────続 き Continuing on the front page (72) Katsuaki Kaifu 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd. (72) Masakazu Kato 1-7-12 Toranomon, Minato-ku, Tokyo No. Oki Electric Industry Co., Ltd. (56) References JP-A-2-216445 (JP, A) Yoshinori Saida et al. "Chaos in excitable artificial lipid membranes" IEICE Technical Report, Vol. 91, 370 (1991) P13-20 (58) Field surveyed (Int. Cl. ⁶ , DB name) G01N 27/00 G01N 27/416 JICST file (JOIS)

Claims (6)

(57) [Claims] 1. A method for recognizing a chemical substance based on chaotic oscillation caused by the chemical substance in an excitable artificial membrane in a state where a current obtained by superimposing an alternating current on a direct current is provided. At least one piece of information on the amplitude and frequency of the alternating current to be changed and the shape of the attractor in the limit cycle state is obtained and stored in advance for each chemical substance, and information corresponding to the stored information is recognized. A method for recognizing a chemical substance, wherein a target chemical substance is obtained, and the obtained information is compared with the stored information to thereby recognize the chemical substance to be recognized. 2. The method for recognizing a chemical substance according to claim 1, wherein the stored information is at least two pieces of information of an amplitude, a frequency, and a shape of an attractor of the alternating current. How to recognize chemical substances. 3. The chaos information as collation information for recognizing a chemical substance based on chaos oscillation caused by the chemical substance in an excitable artificial membrane in a state where a current obtained by superimposing an alternating current on a direct current is applied. A chemical substance recognition information storage method, wherein at least one information of an amplitude and a frequency of the alternating current for changing oscillation to a limit cycle and a shape of an attractor in the limit cycle state is stored in advance. 4. The chemical substance recognition information storage method according to claim 3, wherein the stored information is at least two pieces of information of an amplitude, a frequency, and a shape of an attractor of the alternating current. Recognition information storage method for chemical substances. 5. A receiving portion made of an excitable artificial membrane that generates an electric chaotic oscillation, a current source for applying a current obtained by superimposing an alternating current to a direct current to the excitable artificial membrane, Information processing for measuring at least one of the amplitude and frequency of the alternating current that changes chaotic oscillation caused by a chemical substance into a limit cycle in an excitable artificial membrane in an applied state and a shape of an attractor in the limit cycle state A storage unit for storing the measured information, and a recognition unit for recognizing the chemical substance by comparing the information stored in the storage unit with information about a chemical substance to be recognized corresponding to the information. A chemical substance sensing system comprising: an information processing unit having: 6. The chemical substance sensing system according to claim 5, wherein the information to be measured is at least two of the amplitude and frequency of the alternating current and the shape of the attractor in the limit cycle state. Chemical substance sensing system.