JP2755766B2 - Gas sensor - Google Patents
Gas sensorInfo
- Publication number
- JP2755766B2 JP2755766B2 JP2046237A JP4623790A JP2755766B2 JP 2755766 B2 JP2755766 B2 JP 2755766B2 JP 2046237 A JP2046237 A JP 2046237A JP 4623790 A JP4623790 A JP 4623790A JP 2755766 B2 JP2755766 B2 JP 2755766B2
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- JP
- Japan
- Prior art keywords
- comb
- gas
- gas sensor
- electrode
- shaped
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
Description
【発明の詳細な説明】 （イ）産業上の利用分野 本発明はガスセンサー、更に詳しくは、特定の立体構
造を有する化学種であるゲストと、そのゲストと選択的
に相互作用を行うホストとの間でゲスト−ホスト錯体を
形成する包接現象を応用したガスセンサーに関する。The present invention relates to a gas sensor, and more specifically, a gas sensor having a specific three-dimensional structure, a guest, and a host that selectively interacts with the guest. The present invention relates to a gas sensor using an inclusion phenomenon that forms a guest-host complex between the two.
（ロ）従来の技術 従来、可燃性ガス漏れ警報器やガス濃度計に用いられ
るガスセンサーとして、金属酸化物焼結体型半導体ガス
センサーや接触燃焼式ガスセンサーが普及している。こ
れらのセンサーの検出原理は半導体ガスセンサーでは半
導体表面とガスの吸着現象により、電気抵抗や仕事関数
などの物性が変化するという性質を利用するものであ
り、又、接触燃焼式ガスセンサーはガス検知機能を持つ
物質の表面のガスの接触燃焼による温度変化を電気抵抗
変化として検知することを利用している。(B) Conventional technology Conventionally, as a gas sensor used for a flammable gas leak alarm or a gas concentration meter, a metal oxide sintered body type semiconductor gas sensor and a contact combustion type gas sensor have been widely used. The detection principle of these sensors is based on the fact that semiconductor gas sensors use the property that physical properties such as electrical resistance and work function change due to the phenomenon of gas adsorption to the semiconductor surface.The contact combustion gas sensor uses gas detection. It utilizes the detection of temperature change due to catalytic combustion of gas on the surface of a substance having a function as a change in electrical resistance.
（ハ）発明が解決しようとする課題 然し乍ら、上記従来のガスセンサーでは、ガスの吸着
現象や燃焼現象などを利用していたため、被検ガス中の
各種ガスに対して反応してしまい、特定ガスのみ選択的
に検知することが困難であった。(C) Problems to be Solved by the Invention However, in the above-mentioned conventional gas sensor, since a gas adsorption phenomenon, a combustion phenomenon, and the like are utilized, the gas sensor reacts with various gases in the gas to be detected, and a specific gas is detected. Only it was difficult to selectively detect.
又、これ等のガスセンサーの作動温度が一般に200〜5
00℃と高温を必要とするため素子の劣化が起こりやすい
という問題点があった。In addition, the operating temperature of these gas sensors is generally 200 to 5
Since a high temperature of 00 ° C. is required, there is a problem that the element is likely to deteriorate.
（ニ）課題を解決するための手段 本発明によるガスセンサーは、圧電基板上に櫛型励振
電極と櫛型受信電極とを設け、これ等の両電極間位置に
被検出ガスをゲストとするホストを含む薄膜を被着して
いる。(D) Means for Solving the Problems A gas sensor according to the present invention is provided with a comb-shaped excitation electrode and a comb-shaped receiving electrode on a piezoelectric substrate, and a host having a gas to be detected as a guest between the two electrodes. Is deposited.
（ホ）作用 本発明によれば励振、受信両電極間の被検出ガスをゲ
ストとするホストを含む薄膜がそのゲストと相互作用し
て質量が増加し、両電極間での弾性表面波の伝播条件が
変化することからその被検出ガスに対して選択的な検知
作用を果たす。(E) Function According to the present invention, the thin film containing the host whose guest is the gas to be detected between the excitation and reception electrodes interacts with the guest to increase the mass, and the surface acoustic wave propagates between the electrodes. Since the conditions are changed, a selective detecting action is performed on the detected gas.
（ヘ）実施例 以下、本発明の一実施例を図面を用いて詳細に設計す
る。第１図は本発明のガスセンサーの概略図を例示した
ものである。（１）はガスセンサーの主要部を成す圧電
体基板で、例えば長さ10mm、幅2mm、厚さ0.1mmのLiNbO3
から構成されている。（２）はこの基板（１）の表面の
一側に設けられた弾性表面波（３）を励振する櫛型励振
電極、（４）はこの櫛型励振電極（２）に対向して圧電
体基板（１）の他側に設けられた櫛型受信電極で、櫛型
励振電極（２）から圧電体基板（１）の表面を伝播して
来る弾性表面波（３）を受信して電気信号に変換する働
きを為す。これ等の櫛型電極（２）（４）は対数50対、
電極間隔５μｍ、交差長1mm、電極厚み1000Åのアルミ
ニウム蒸着膜にて構成されている。（５）は両櫛型電極
（２）（４）間の圧電体基板（１）表面を被覆した被検
出ガスをゲストとするホストを含む薄膜で、例えば膜厚
100nmのγ−シクロデキストリンの薄膜が用いられる。
この薄膜（５）は真空度10-6Torr、基板温度25℃の条件
下の真空蒸着法によって形成される。第２図にこのγ−
シクロデキストリンの化学構造式を示す。(F) Example Hereinafter, an example of the present invention will be designed in detail with reference to the drawings. FIG. 1 illustrates a schematic view of a gas sensor according to the present invention. (1) is a piezoelectric substrate constituting a main part of a gas sensor, for example, LiNbO 3 having a length of 10 mm, a width of 2 mm, and a thickness of 0.1 mm.
It is composed of (2) is a comb-shaped excitation electrode for exciting a surface acoustic wave (3) provided on one side of the surface of the substrate (1), and (4) is a piezoelectric body opposed to the comb-shaped excitation electrode (2). A comb-shaped receiving electrode provided on the other side of the substrate (1) receives a surface acoustic wave (3) propagating on the surface of the piezoelectric substrate (1) from the comb-shaped excitation electrode (2) and outputs an electric signal. It works to convert to. These comb electrodes (2) and (4) have a logarithm of 50 pairs,
It is composed of an aluminum deposited film having an electrode interval of 5 μm, a cross length of 1 mm, and an electrode thickness of 1000 °. (5) is a thin film containing a host whose guest is a gas to be detected, which covers the surface of the piezoelectric substrate (1) between the two comb-shaped electrodes (2) and (4).
A 100 nm γ-cyclodextrin thin film is used.
This thin film (5) is formed by a vacuum evaporation method under the conditions of a degree of vacuum of 10 −6 Torr and a substrate temperature of 25 ° C. FIG. 2 shows this γ-
1 shows a chemical structural formula of cyclodextrin.
次にこのような構成のガスセンサーの動作について説
明する。大気中において櫛型励振電極（２）に連なった
入力端子（６）によりインパルス電圧を印加すると、櫛
型励振電極（２）は、圧電効果により隣り合う電極間に
互いに逆位相の歪みが生じ、弾性表面波（３）が励起さ
れる。この弾性表面波（３）は基板（１）の表面を伝播
し、櫛型受信電極（４）に到達し電気エネルギーに変換
され、出力端子（７）から高周波出力として取り出され
る。Next, the operation of the gas sensor having such a configuration will be described. When an impulse voltage is applied from the input terminal (6) connected to the comb-shaped excitation electrode (2) in the atmosphere, the comb-shaped excitation electrode (2) generates opposite-phase distortions between adjacent electrodes due to a piezoelectric effect. The surface acoustic wave (3) is excited. The surface acoustic wave (3) propagates on the surface of the substrate (1), reaches the comb-shaped receiving electrode (4), is converted into electric energy, and is extracted from the output terminal (7) as a high-frequency output.
斯る構成のセンサーの櫛型励振電極（２）と櫛型受信
電極（４）との間に第３図に示すように帰還増幅回路
（８）を接続し、櫛型受信電極（４）で受信した信号を
の帰還増幅回路（８）で増幅して再び櫛型励振電極
（２）に帰還することによって発振回路を構成してい
る。A feedback amplifier circuit (8) is connected between the comb-shaped excitation electrode (2) and the comb-shaped reception electrode (4) of the sensor having such a configuration as shown in FIG. An oscillation circuit is constituted by amplifying the received signal by the feedback amplifier circuit (8) and returning it to the comb-shaped excitation electrode (2) again.
このようにして動作しているセンサーを第４図に示す
ようにガスセル（10）内に固定し、このガスセル（10）
内に四塩化炭素蒸気を導入すると、センサーと帰還増幅
回路（８）とのよる発振周波数は低下し始め、その低下
現象は５分後にはその低下した周波数で安定した状態と
なった。The sensor operating in this manner is fixed in a gas cell (10) as shown in FIG.
When the carbon tetrachloride vapor was introduced thereinto, the oscillation frequency of the sensor and the feedback amplifier circuit (8) began to decrease, and the decrease phenomenon became stable at the reduced frequency after 5 minutes.
この現象は、γ−シクロデキストリンの薄膜（５）の
分子内部の空洞内に四塩化炭素分子が填まり込んでホス
ト−ゲスト錯体を形成し、このγ−シクロデキストリン
の薄膜（５）の質量が増加することによって櫛型励振電
極（２）から圧電体基板（１）の表面を櫛型受信電極
（４）へ伝播して来る弾性表面波（３）の伝播条件が変
化することが原因と考えられている。また一旦周波数が
低下した状態からガスセル（10）内に窒素ガスを導入す
ることによって、γ−シクロデキストリンの薄膜（５）
の分子内部の空洞から四塩化炭素分子が排出され、ホス
ト−ゲスト錯体が崩壊するので発振回路の発振周波数は
元の値まで回復した。This phenomenon occurs because carbon tetrachloride molecules are packed into the cavities inside the molecules of the γ-cyclodextrin thin film (5) to form a host-guest complex, and the mass of the γ-cyclodextrin thin film (5) is reduced. It is thought that the propagation condition of the surface acoustic wave (3) propagating from the comb-shaped excitation electrode (2) to the comb-shaped receiving electrode (4) changes from the comb-shaped excitation electrode (2) to the comb-shaped receiving electrode (4). Have been. Further, by introducing nitrogen gas into the gas cell (10) from a state where the frequency has been lowered, a thin film of γ-cyclodextrin (5) is introduced.
The carbon tetrachloride molecule was discharged from the cavity inside the molecule, and the host-guest complex collapsed, so that the oscillation frequency of the oscillation circuit was restored to the original value.
同様の条件で四塩化炭素の代わりにクロロホルム蒸気
を用いた場合は、発振周波数の変化は僅かであった。構
造が類似したハロゲン化炭化水素である四塩化炭素と、
クロロホルムとでこのような違いが見られるのは、γ−
シクロデキストリンの薄膜（５）の分子内部の空洞径が
四塩化炭素分子の大きさとほぼ等しいためこの四塩化炭
素分子はγ−シクロデキストリンとホスト−ゲスト錯体
を形成するのに対し、クロロホルム分子は四塩化炭素分
子より小さいため、その分子がγ−シクロデキストリン
の薄膜（５）の分子内部の空洞に填まり込んでも直ちに
離脱してしまい、ホスト−ゲスト錯体を形成することが
できないためであろう。When chloroform vapor was used instead of carbon tetrachloride under the same conditions, the change in oscillation frequency was slight. Carbon tetrachloride, a halogenated hydrocarbon having a similar structure;
This difference between chloroform and γ-
Since the cavity diameter inside the molecule of the cyclodextrin thin film (5) is almost equal to the size of the carbon tetrachloride molecule, the carbon tetrachloride molecule forms a host-guest complex with γ-cyclodextrin, whereas the chloroform molecule forms the host molecule. Because it is smaller than the carbon chloride molecule, even if the molecule enters the cavity inside the molecule of the thin film of gamma-cyclodextrin (5), it is immediately separated and cannot form a host-guest complex.
ここで本発明ガスセンサーの動作の具体的な数値を挙
げて説明しておく。第３図に示した発振回路で大気中に
おいて90MHzの発振を行わしめていた状態から、その発
振回路を第４図のガスセル（10）内に置いて四塩化炭素
ガス（９）を導入すると、その発振周波数は５分後に50
0Hz低下した。また対比例としてクロロホルムの場合は1
0Hzの周波数変化であった。Here, specific numerical values of the operation of the gas sensor of the present invention will be described. When the oscillation circuit shown in FIG. 3 oscillates at 90 MHz in the atmosphere, the oscillation circuit is placed in the gas cell (10) in FIG. 4 and carbon tetrachloride gas (9) is introduced. Oscillation frequency is 50 after 5 minutes
0Hz dropped. For chloroform, 1 for chloroform
The frequency change was 0 Hz.
（ト）発明の効果 本発明は以上の説明から明らかなように、圧電体基板
上に櫛型例振電極と櫛型受信電極とを設け、これらの両
電極間位置に被検出ガスをゲストとするホストを含む薄
膜を被着しているので、この薄膜の特定ガスに対する選
択的なホスト−ゲスト錯体形成によって生じる薄膜の重
量変化を周波数変化として検知している。従って接触燃
焼式又は半導体式ガスセンサーなどの従来のセンサーで
は不可能である特定ガスに対する選択検知が可能となる
と同時に、検知作動は室温雰囲気で行えるので素子の劣
化は少なく長寿命化が図れる。(G) Advantages of the Invention As is clear from the above description, the present invention provides a comb-shaped sample vibration electrode and a comb-shaped receiving electrode on a piezoelectric substrate, and a gas to be detected is placed between the two electrodes at the position of the guest. Since a thin film containing a host is deposited, a change in weight of the thin film caused by the selective formation of a host-guest complex with respect to a specific gas in the thin film is detected as a change in frequency. Therefore, it is possible to selectively detect a specific gas, which is impossible with a conventional sensor such as a catalytic combustion type or semiconductor type gas sensor, and at the same time, since the detection operation can be performed in a room temperature atmosphere, deterioration of the element is small and a long life can be achieved.
第１図は本発明ガスセンサーの素子の斜視図、第２図は
本発明に用いられるγ−シクロデキストリンの化学構造
式、第３図はガスセンサーの構成を示す斜視図、第４図
はガス検知状態を示す断面図である。 （１）……圧電体基板、 （２）……櫛型励振電極、 （３）……表面弾性波、 （４）……櫛型受信電極、 （５）……γ−シクロデキストリン薄膜、 （８）……帰還増幅回路、 （９）……ガス、 （10）……ガスセル。FIG. 1 is a perspective view of the element of the gas sensor of the present invention, FIG. 2 is a chemical structural formula of γ-cyclodextrin used in the present invention, FIG. 3 is a perspective view showing the structure of the gas sensor, and FIG. It is sectional drawing which shows a detection state. (1) ... piezoelectric substrate, (2) ... comb-shaped excitation electrode, (3) ... surface acoustic wave, (4) ... comb-shaped receiving electrode, (5) ... gamma-cyclodextrin thin film, ( 8)… feedback amplifier circuit, (9)… gas, (10)… gas cell.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 黒木 和彦 大阪府守口市京阪本通２丁目18番地 三 洋電機株式会社内 (56)参考文献 特開 昭62−190905（ＪＰ，Ａ) 特表 昭64−500051（ＪＰ，Ａ) ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Kazuhiko Kuroki 2-18-18 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (56) References JP-A-62-190905 (JP, A) 64-500051 (JP, A)
Claims (3)
弾性表面波を励振する櫛型励振電極とその電極から上記
圧電体基板表面を伝播して来る弾性表面波を受信する櫛
型受信電極とを設けると共に、これ等両電極間の上記圧
電体基板表面の少なくとも一部に被検出ガスをゲストと
するホストを含む薄膜を被着してなるガスセンサー。1. A piezoelectric substrate on which a surface acoustic wave propagates,
A comb-shaped excitation electrode for exciting a surface acoustic wave; and a comb-shaped receiving electrode for receiving a surface acoustic wave propagating from the electrode to the surface of the piezoelectric substrate, and the surface of the piezoelectric substrate between these two electrodes. A gas sensor in which a thin film containing a host having a gas to be detected as a guest is applied to at least a part of the gas sensor.
構成されてなることを特徴とした請求項（１）記載のガ
スセンサー。2. The gas sensor according to claim 1, wherein said thin film is composed of γ-cyclodextrin.
帰還増幅回路を接続して発振回路を構成させて成る請求
項（１）又は（２）記載のガスセンサー。3. The gas sensor according to claim 1, wherein a feedback amplification circuit is connected between said comb-shaped excitation electrode and said comb-shaped reception electrode to form an oscillation circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2046237A JP2755766B2 (en) | 1990-02-27 | 1990-02-27 | Gas sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2046237A JP2755766B2 (en) | 1990-02-27 | 1990-02-27 | Gas sensor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH03248057A JPH03248057A (en) | 1991-11-06 |
| JP2755766B2 true JP2755766B2 (en) | 1998-05-25 |
Family
ID=12741519
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2046237A Expired - Fee Related JP2755766B2 (en) | 1990-02-27 | 1990-02-27 | Gas sensor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2755766B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005510693A (en) * | 2001-10-01 | 2005-04-21 | ロッキード・マーチン・コーポレイション | Ram air sample collector for chemical weapons sensor |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5323636A (en) * | 1993-06-11 | 1994-06-28 | The United States Of America As Represented By The Secretary Of The Army | Dual-channel flexural acoustic wave chemical sensor |
| US6582583B1 (en) | 1998-11-30 | 2003-06-24 | The United States Of America As Represented By The Department Of Health And Human Services | Amperometric biomimetic enzyme sensors based on modified cyclodextrin as electrocatalysts |
| JP4164580B2 (en) * | 2004-07-12 | 2008-10-15 | 国立大学法人 新潟大学 | Gas detection method and gas sensor |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS62190905A (en) * | 1986-02-18 | 1987-08-21 | Matsushita Electric Ind Co Ltd | Surface acoustic wave device |
-
1990
- 1990-02-27 JP JP2046237A patent/JP2755766B2/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005510693A (en) * | 2001-10-01 | 2005-04-21 | ロッキード・マーチン・コーポレイション | Ram air sample collector for chemical weapons sensor |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH03248057A (en) | 1991-11-06 |
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