JP3316065B2 - pressure sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure sensor using an optical material.

[0002]

2. Description of the Related Art Conventionally, a device using a diamond anvil has been widely used as a high-pressure generating / measuring device because of its easy handling. This device measures pressure by using the fact that the optical properties of ruby crystals in a sample change with pressure, mixes powdered ruby microcrystals with the sample, and irradiates the sample with laser light. And measure the fluorescence emitted by the ruby crystal. Here, when the pressure applied to the sample increases, the energy level of the ruby crystal as the pressure sensing member changes, and the wavelength of the fluorescent light changes to the longer wavelength side. Since it is known that the amount of change depends almost linearly on the applied pressure, pressure can be detected by measuring the change in wavelength.

[0003]

However, since ruby crystals have a strong absorption band in the visible or near-infrared region, when pressure is detected simultaneously with measurement of the infrared characteristics of the sample,
The effects cannot be avoided. In addition, ruby powdery crystals are used by mixing them into the sample, but it is generally difficult to evaluate the effect of the crystals on the physical properties of the sample, and it is virtually impossible to estimate the change in physical properties due to the interaction between the sample and the ruby crystal. It is possible. Such a problem becomes a major obstacle to precisely examining the relationship between the physical properties of the sample and the pressure.

Accordingly, a pressure sensing member which does not have a strong absorption band in the visible or near-infrared region and does not need to be mixed with the sample is provided, and does not adversely affect the measurement of the optical characteristics of the sample. There is a need for a pressure measuring device.

The present invention has been made to solve such problems, and has as its object to provide a pressure sensor capable of precisely measuring the optical response of a sample under high pressure. It is.

[0006]

In order to achieve the above object, the present inventors have conducted intensive studies and have found that two perpendicular directions, such as a thin film in which linear organic molecules are arranged in parallel. Have a difference in effective mass, that is, by using a directional thin film as an optical material, it has been found that optical information according to a pressure change can be detected, and the pressure sensor of the present invention has been invented.

That is, a pressure sensor according to the present invention comprises a pressure sensing member made of a thin film optical material having an effective mass ratio of 0.5 or less in two directions perpendicular to each other along the film direction; A light receiving device having a light receiving sensitivity in a wavelength region including an absorption band, and a light emitting device having a light emitting characteristic in a wavelength region including the light absorption band of the optical material, wherein the effective mass ratio caused by a pressure applied to the optical material The change is detected by a change in the wavelength of the light absorption band of the optical material.

Hereinafter, the present invention will be described in detail.

In a material in which a large number of molecules having directionality are regularly arranged, such as an organic polymer thin film in which chain polymers are arranged in parallel, the direction along the chain of the molecule (chain direction) and the direction perpendicular to the chain (chain direction) And the effective mass of electrons, which is usually measured using cyclotron resonance. When pressure is applied to such a material in the inter-chain direction perpendicular to the molecular chain direction, the pressure changes the ratio of the inter-molecular interaction to the intra-molecular interaction. It can be captured as a decrease in the ratio of the effective mass of electrons / effective mass in the interchain direction. On the other hand, the relationship between the effective mass ratio in the chain direction / interchain direction and the lowest energy level of the exciton is as shown in FIG. 1, and the energy level shifts due to the decrease in the effective mass ratio, With this shift, the peak of the light absorption spectrum of the material shifts. Here, specifically, the relationship between the energy level and the light absorption spectrum of a poly (1,4-di (paratoluenesulfonatemethyl) -1,3-butadiyne thin film having the effective mass ratio of 0.3 is shown. The peak displacement of the light absorption spectrum when pressure is applied to such a thin film optical material is shown in Fig. 3. Fig. 3 shows that the effective mass ratio decreases when pressure is applied to the material as shown in the figure. As a result, the energy level shifts, and the peak of the light absorption spectrum shifts from the wave number ω1 to the wave number ω2. Therefore, if the shift width Δω of the peak of the light absorption spectrum is detected, the effective mass ratio is reduced. It can be seen that it is possible to determine the pressure applied to the material via

Further, as shown in FIG. 1, the effective mass ratio and the lowest energy level of a material having molecular orientation have a relation that the energy level becomes the maximum value when the effective mass ratio is around 0.5. Within an effective mass ratio of about 0.5 or less, the energy level changes monotonically with the pressure applied to the material. Accordingly, in this range, the effective mass ratio and the energy level correspond one-to-one, and the amount of change is large. Therefore, the optical material which can change the effective mass ratio in the two-dimensional direction within the range of 0.5 or less. Is used as a pressure sensing member, and the pressure can be detected by measuring the light absorption spectrum of the pressure sensing member. In other words, the pressure sensor of the present invention measures an optical absorption spectrum of the pressure sensing member using an optical material whose effective mass ratio can change within a range of about 0.5 or less as a pressure sensing member. In the pressure sensor of the present invention, the pressure is not limited to the case where the pressure is applied only in the inter-chain direction perpendicular to the molecular chain direction as described above. Even when pressure is applied, the effective mass ratio similarly decreases in accordance with the magnitude of the pressure, so that the pressure can be detected.

As the thin film optical material having the above-mentioned effective mass ratio, for example, there is an organic molecular thin film having uniform molecular directions. The effective mass ratio and energy level of the organic molecular thin film material can be changed depending on the material, manufacturing method, and the like, and usable materials include linear polymers such as polyethylene, polydiacetylene, linear polyester, and linear polyamide. And substituted polydiacetylenes such as poly (1,4-di (p-toluenesulfonatemethyl) -1,3-butadiyne) [hereinafter referred to as PTS polydiacetylene]. It is not limited to polymers, as long as the effective mass ratio is within the above-mentioned preferred range, and the orientation of the molecules is aligned,
It may be a branched molecule. Therefore, the material is not strictly defined and, even when the molecular orientation is not sufficiently aligned at the time of forming the thin film and the effective mass ratio is not in the preferable range, physical treatment such as stretching is performed. By applying, it is possible to improve the regularity of the molecular arrangement and to have a suitable effective mass ratio. As an example of this, for example, a thin film in which a polysilane resin is subjected to a stretching treatment so as to have directionality in molecular orientation may be mentioned.

At this time, since the light absorption spectrum of the organic molecular thin film can often be steep as shown in FIG. 2, the shift width of the peak and the shift of the energy level can be determined by examining the optical response characteristics of the thin film. It can be easily measured. In the organic molecular thin film, the relationship between the pressure and the effective mass ratio is not known in detail, and varies in a complicated manner depending on various factors. However, the shift width Δω of the peak in the light absorption spectrum is expressed in terms of energy with respect to the pressure. Is about 0.1 eV / GPa. Therefore, pressure can be easily derived from these relationships in the pressure sensor of the present invention. In addition, by appropriately selecting a thin-film optical material having an absorption peak in a region away from the absorption band of the sample, interference of the absorption spectrum between the pressure sensing member and the sample can be avoided. Simultaneous and independent measurement of the spectrum of the sample becomes possible.

Hereinafter, embodiments of the pressure sensor according to the present invention will be described in detail.

[0014]

FIG. 4 is a schematic view showing a first embodiment of the pressure sensor according to the present invention. In this example, a PTS polydiacetylene thin film having a uniform molecular direction is used as the pressure sensing member.

That is, the pressure sensor 1
A pair of diamond anvils 11 and 13 are provided, and a thin film plate 15 as a pressure sensing member made of PTS polydiacetylene is bonded and fixed to the anvil 11. The thin film plate 15 is installed perpendicular to the axial direction of the anvils 11 and 13. Further, a light emitting device 17 and a light receiving device 19 for irradiating monochromatic light to the axial direction outside of the anvils 11 and 13 are installed so as to face each other.
Perpendicularly to the anvil 11, the thin film plate 15, and the anvil 13
, And the intensity of the transmitted light is measured by the light receiving device 19.

Here, the atmospheric pressure around the pressure sensor 1 acts on the thin film plate 15, the effective mass ratio decreases in accordance with the pressure, and the lowest energy level of the excitons changes. It is detected in the light absorption spectrum of the transmitted light measured. Specifically, since the light that resonates with the exciton level of PTS polydiacetylene is about 600 nm, the pressure is detected by light absorption in a slightly shorter wavelength region.

A sample 21 for optical measurement is arranged between the anvil 11 and the anvil 13, and sequentially changes the wavelength of light emitted from the light emitting device 17. The sample 17 and the thin film plate 15 are under the same atmosphere, and the light irradiated from the light emitting device 17 is transmitted through the thin film plate 15 and the sample 21 and detected by the light receiving device 19, whereby the atmospheric pressure and the IR of the sample are measured.
Thus, a light absorption spectrum including information on optical characteristics such as the above can be obtained, and therefore, pressure information and information on the optical characteristics of the sample can be obtained simultaneously. The thin film plate 15 is an anvil 1
Since it is fixed to 1, the measurement sample and the pressure sensing member are not mixed as in the conventional apparatus.

FIG. 6 is a schematic view showing a second embodiment of the pressure sensor of the present invention. In this embodiment, the pressure sensor 3 is integrally attached to a measurement chamber C for measuring optical characteristics of a sample.

Here, the pressure-sensitive plate 31 is disposed in the vertical direction, and is provided so as to be movable in the horizontal direction with respect to the wall 33 of the pressure sensor 3. The pressure-sensitive plate 31 is pressed to the left in the drawing by the pressure of the measurement chamber C, and the horizontal arm 35 integrated with the pressure-sensitive plate 31 also moves to the left. An arm 3 rotatably provided around a pin 37 with respect to a horizontal arm 35
9 extends downward, and the left side of the arm 39 is supported by a fulcrum 41. A thin plate 43 as a sensing member made of PTS polydiacetylene is horizontally arranged on the right side of the lower portion of the arm 39, the right end is fixed, and the left end of the thin plate 43 is in contact with the lower right side of the lower end of the arm 39. Further, the light emitting device 45 and the light receiving device 47 are arranged above and below the thin film plate 43 so as to face each other.
And is detected by the light receiving device 47. The position of the fulcrum 41 is designed to be changeable in the vertical direction, and is configured so that the force applied to the thin film plate 43 by the movement of the horizontal arm 35 can be adjusted.

In the above configuration, the horizontal arm 35 moves to the left with the movement of the pressure-sensitive plate 31 pressed leftward by the pressure of the measuring chamber C. As a result, the upper end of the arm 39 is pressed leftward, but is supported by the fulcrum 41, so that the lower end of the arm 39 moves rightward and presses the thin film plate 43 in the horizontal direction. Due to this pressure, the effective mass ratio of the thin film plate 43 changes, and the absorption spectrum of light transmitted through the thin film plate 43 and received by the light receiving device 47 changes. or,
Even when the pressure in the measurement chamber C greatly fluctuates, the force applied to the thin film plate 43 can be regulated to a certain level by changing the position of the fulcrum 41, so that the light handled by the light emitting device 45 and the light receiving device 47 can be regulated. For example, a wide range of pressure can be detected only within the range of monochromatic light without widening the wavelength range of.

Therefore, in the second embodiment, the light emitting device 45 and the light receiving device 47 need only be able to cope with light in the wavelength range necessary only for pressure detection, so that the light emitting device 45 and the light receiving device 47 can be simplified. .

In the first and second embodiments, the pressure is calculated by detecting the light transmitted through the thin film plate.
The present invention is not limited to this, and the intensity of reflected light may be measured instead of transmitted light. Further, as described above, a material other than PTS polydiacetylene can be used for the thin film plate, and an appropriate wavelength of the light emitting and receiving device is appropriately set according to the resonance wavelength of the material.

[0023]

As described above, according to the pressure sensor of the present invention, it is possible to perform measurement with high accuracy without adversely affecting the measurement of the optical characteristics of the sample under high pressure, etc. The value is extremely large.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between an effective mass ratio in a two-dimensional direction of a thin film optical material and a lowest energy level of an exciton.

FIG. 2 is a diagram showing a relationship between an energy level of an exciton of a thin film optical material and a light absorption spectrum.

FIG. 3 is a diagram showing a displacement of a peak of a light absorption spectrum of FIG. 2 due to a pressure applied to a thin film optical material.

FIG. 4 is a schematic diagram showing a schematic structure of a first embodiment of the pressure sensor of the present invention.

FIG. 5 is a schematic view showing a schematic structure of a pressure sensor according to a second embodiment of the present invention.

[Explanation of symbols]

 1, 3 Pressure sensor 11, 13 Anvil 15 Thin film plate 17 Light emitting device 19 Light receiving device 21 Sample 43 Thin film plate 45 Light emitting device 47 Light receiving device

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01L 11/02 G01N 21/27 JICST file (JOIS)

Claims (2)

(57) [Claims] A pressure sensing member comprising a thin film optical material in which chain molecules are oriented ; a light receiving device having a light receiving sensitivity in a wavelength region including a light absorption band of the optical material; light of a light emitting device having a light-emitting characteristics in a wavelength region, the pressure applied to the optical material, due to the pressure containing
Chain direction of the chain molecule of the chemical material and between the chains perpendicular to the chain direction
A pressure sensor, wherein the pressure is detected by the light receiving device as a change in a wavelength of a light absorption band of the optical material caused by a change in an effective mass ratio of electrons in a direction . 2. The method according to claim 1, wherein the thin film-shaped optical material is subjected to a pressure to be detected.
Therefore, the effective mass ratio that changes is in the range of 0.5 or less.
The pressure sensor according to claim 1, wherein the pressure sensor is an organic polymer thin film.