JP3098792B2 - Taste sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an artificial sensor capable of acting on behalf of the five senses of human beings, and more particularly, to a sensor or transducer that can substitute for human sensation, such as taste, which has heretofore been considered impossible by artificial sensors. Electronic device called.

[0002]

2. Description of the Related Art The same applicant has previously filed a patent application for the invention of "taste sensor and its manufacturing method" (Japanese Patent Application No. 1-1908).
No. 19; hereinafter referred to as the first prior invention of the same applicant), and according to the specification and drawings, a so-called lipid molecule group accommodated in a surface matrix of a certain high molecular polymer with a specific molecular arrangement. Showed that the sensor was sensitive to saltiness, sourness, bitterness, and sweetness called basic taste. Moreover, it has been shown that this type of sensor can measure taste instead of taste, which is one of the human five senses.

[0003] To explain this more specifically, in the prior application of the same applicant, for example, polyvinyl chloride (PVC) is used as a polymer and a plasticizer such as dioctyl phthalate (DOP) is used. And lipids are roughly 2:
The mixture at a weight ratio of 3: 1 was melted in tetrahydrofuran (THF), transferred to a flat-bottomed container, and kept on a uniformly heated plate at about 30 ° C. for 2 hours to volatilize THF and evaporate lipid. A membrane, ie, a lipidic molecular membrane housed in a PVC surface matrix, has been obtained. Experiments have confirmed that this lipid membrane serves as a taste sensor.

However, using a lipid membrane formed in this way as a sensor, although a measurement result can be obtained to a certain extent, the production method of placing lipid molecules in the surface matrix of a high molecular polymer requires a molecular level. Structure is not constant,
In other words, it is not always possible to obtain a constant surface matrix itself, and it is difficult to guarantee that a lipid membrane containing lipid molecules is always of constant quality. The orientation of the reactive molecules is also poor, and therefore, the measurement of the membrane potential and the electric resistance is likely to cause variations in the data and the sensitivity is insufficient.

[0005] Also, the types of lipid molecules that can be relatively easily accommodated in the surface matrix of a high molecular polymer have been limited. For example, phosphatidylcholine (P
Lipids constituting a biological membrane, such as C), have poor compatibility with a polymer material such as polyvinyl chloride (PVC), and thus it has been difficult to form a lipid membrane used for a taste sensor.

Accordingly, the same applicant has also filed a patent application for the invention of “taste sensor and method of manufacturing the same” (Japanese Patent Application No. 3-020450; hereinafter, referred to as a second prior invention of the same applicant). According to the description and the drawings,
Taste sensor of the prior application (hereinafter referred to as taste sensor A)
Has been improved by focusing on the following three points (hereinafter referred to as a taste sensor).
(Referred to as taste sensor B). That is, the quality of the taste sensor is made constant. Improve the quality of taste sensor. Increase the number of taste sensors. (Diversify) The taste sensor B is formed on a base film made of a substance having a property of being familiar with a hydrophobic part of a molecule of a bitter substance formed on a substrate surface or a substance having a property of being familiar with a hydrophobic part of an amphipathic molecule. It has a structure in which a monomolecular film of an amphipathic substance or a bitter substance is formed, and lipids, which cannot be used in the taste sensor A, can be used as a material, so that the types have become abundant.

FIG. 2 shows an example in which a single layer of an amphipathic molecule group having such a structure is processed into a taste sensor. In the figure, 1, 2, 3, and 3 'are a single layer of a substrate, a base film, and an amphipathic molecule group, respectively. The amphipathic molecules of the unnecessary portions 8, 8 'are removed, and conductive rods (eg, gold or silver) 5, 5' serving as electrodes are inserted into the holes 7, 7 'provided in the substrate 1, One end of the rod is brought into contact with the base film 2, and the other end is soldered with lead wires 6, 6 '. Thus, the potential of the membrane of the amphipathic molecule can be measured. Various experiments were performed using the taste sensor B shown in FIG. 2, and the obtained data proved that the taste sensor B was a highly sensitive taste sensor having less variation in quality than the taste sensor A. I have.

[0008]

However, the taste sensor B
But there were still issues that had to be resolved. That is, the membrane potential of the taste sensor B changes with time. Compared with the taste sensor A, the variation in the time characteristic was smaller (the quality was stable), and the range of the variation was smaller. In particular, when the taste sensor is immersed in the solution to be measured and then used for a single-time measurement, for example, within about one minute, the quality is improved several steps. However, when the measurement is performed in a state of being immersed in the solution for a long time, the amount of change in the membrane potential is large enough to be an obstacle. SUMMARY OF THE INVENTION It is an object of the present invention to obtain a taste sensor with less fluctuation in membrane potential over time.

[0009]

Means for Solving the Problems In order to solve the above-mentioned problems, a monomolecular film composed of a molecule group of an amphipathic substance or a bitter substance is used as a structure of a taste sensor, and the membrane potential of the monomolecular film is measured. A buffer layer is provided between the electrode and the monomolecular film.

[0010]

The buffer layer keeps the concentration of anions around the electrode constant and can apply a salt concentration gradient to the membrane, so that the membrane can be placed closer to the biological system. This buffer layer suppresses the ions in the solution to be measured from reaching the metal as the electrode and fluctuating the potential between the electrode and the membrane.

[0011]

FIG. 1 is a schematic view (cross-sectional view) of a taste sensor made for an experiment. A 0.5 mmφ hole was penetrated through a glass flat substrate 1, and a silver round bar was inserted into the hole. A buffer layer (buffer) is provided at a portion in contact with the base film 2 holding the monomolecular film 3.
Layer 4). 100 mM in this example as a buffer layer
Although a potassium chloride solution of (m mol / l) was used, the buffer layer is not a liquid, and for example, potassium chloride may be mixed in agar or the like. Further, not only potassium chloride but also sodium chloride and calcium chloride can be used. For example, it is desirable that the cation (potassium ion) and the anion (chlorine ion) have the same penetration rate, such as potassium chloride.

Next, a method of an experiment conducted using the taste sensor manufactured as described above and data obtained as a result will be described. 3 and 4 show the relationship between the concentration of sodium chloride (NaCl) and the membrane potential of the taste sensor of the present invention and the conventional taste sensor (taste sensor B).

The experiment was performed on the taste sensor of 5 samples each according to the following procedures. Immerse the taste sensor in 1 mM potassium chloride solution. After about 4 minutes, the membrane potential is measured, and the value is used as a reference. While the taste sensor is immersed in the solution, sodium chloride is added to make a solution of potassium chloride 1 mM and sodium chloride 1 mM. After about 4 minutes, the membrane potential is measured, and the difference from the reference value is determined. Hereinafter, the concentration of sodium chloride in the procedure was 3 m.
M, 10 mM, 30 mM, 100 mM, 300 mM, 1000 mM
And repeat the procedure. At this time, if the concentration of sodium chloride is changed, the concentration of potassium chloride decreases due to an increase in the amount of the solution. Therefore, potassium chloride is replenished to maintain 1 mM.

As can be seen from FIGS. 3 and 4, the taste sensor of the present invention and the conventional taste sensor have almost the same sensitivity.

FIGS. 5 and 6 show the change in the membrane potential over time by immersing the taste sensor of the present invention and the conventional taste sensor in a 1 M (mol / l) solution of sodium chloride.
The measurement of the membrane potential was performed at intervals of about 20 seconds.

From these results, as described above, the taste sensor of the present invention has almost the same sensitivity as the conventional taste sensor, but there is almost no change in the membrane potential. Further, the variation of the time characteristic of each taste sensor is extremely small. This result indicates that the taste sensor of the present invention is stable,
It shows that the quality is also constant.

[0017]

According to the present invention, the taste sensor is provided with a monomolecular film having a single layer of the amphipathic molecule group and the bitter substance molecule group, an electrode for measuring the membrane potential, Since the sensor is constituted by the buffer layer provided therebetween, a taste sensor with a small variation in quality and an extremely small change in the membrane potential with the passage of time can be realized while maintaining good sensitivity. If this taste sensor is used, it is not necessary to consider the variation of the reference point.For example, when measuring a number of samples, it is not necessary to immerse the taste sensor in the reference liquid for each sample and measure the reference point. The measurement can be performed without errors due to the deviation of the reference point at the time of measurement from the reference point at the time of measuring the reference liquid.

[0018]

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a taste sensor of the present invention.

FIG. 2 is a diagram schematically showing a conventional taste sensor.

FIG. 3 is a graph showing concentration characteristics of a taste sensor of the present invention with respect to sodium chloride.

FIG. 4 is a diagram showing a concentration characteristic of a conventional taste sensor with respect to sodium chloride.

FIG. 5 is a diagram showing a time characteristic of the taste sensor of the present invention with respect to sodium chloride.

FIG. 6 is a diagram showing a time characteristic of a conventional taste sensor with respect to sodium chloride.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Base film 3 Amphipathic molecule group or bitter substance molecule group 3 'Amphipathic molecule group or bitter substance molecule group 4 Buffer layer 4' Buffer layer 5 Electrode (conductive rod) 5 'electrode (conductive 6 lead wire 6 'lead wire 7 hole 7' hole

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kaoru Yamafuji 1-6-21 Kusakae, Chuo-ku, Fukuoka City, Fukuoka Prefecture (72) Inventor Kiyoshi Toko 2-83-2-2, Miwadai, Higashi-ku, Fukuoka City, Fukuoka Prefecture (72) Inventor Kenji Hayashi 2-14-18-407 Takatori, Sawara-ku, Fukuoka City, Fukuoka Prefecture (72) Inventor Hidekazu Ikezaki 5-27, Minamiazabu, Minato-ku, Tokyo Anritsu Corporation (72) Inventor Rieko Higashikubo Examiner, Anritsu Corporation Jun 10 Koriyama, Minami-Azabu 5-chome, Minato-ku, Tokyo (58) Field surveyed (Int.Cl. ⁷ , DB name) G01N 27/416 JICST file (JOIS)

Claims (1)

(57) [Claims] 1. A substrate (1) wherein at least a part of its surface is covered with a substance having a property of being close to a hydrophobic part of a molecule of a bitter substance or a substance having a property of being close to a hydrophobic part of an amphipathic molecule. A molecule group of bitter substances (3) or a group of amphipathic molecules (3) having a hydrophobic portion and a hydrophilic portion, which are attached so as to cover a substance having a property of being familiar with a hydrophobic portion of the substrate; An electrode (5) for measuring the potential of the group, and a front electrode provided between the electrode and the molecule group.
A taste sensor comprising a buffer layer (4) for keeping the concentration of anions around the electrode constant .