JPS58168953A - Gas and moisture sensitive element - Google Patents

Abstract

PURPOSE:To detect gaseous alcohol selectively with high sensitivity, by constituting a titled element of an element substrate consisting of apatite ceramics, an electrode and a metallic oxide having sensitivity to alcohol. CONSTITUTION:A gas and moisture sensitive element consists of an element substrate 1 of apatite ceramics, electrodes 2, 3, 4, and a metallic oxide 5 which is provided between the electrodes 2 and 4 in contact with the electrodes 2 and 3 and has sensitivity to alcohol. Said element detects humidity with the substrate 1 and gaseous alcohol with the metallic oxide 5 between the separated electrodes provided to the substrate 1. The separated electrode is formed by baking ruthenium oxide and promote the sensitivity to gaseous alcohol. The electric resistance of the element changes remarkably with 0-100% relative humidity or 0- 3,000ppm concn. of gaseous alcohol.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an element for detecting alcohol gas and humidity.

Conventionally, humidity sensing elements have utilized the relative humidity dependence of the electrical conductivity of metal oxides, inorganic and organic electrolytes, and organic materials with conductive substances dispersed therein. It has been often used because of its gender.

Among them, metal oxides have good stability and heat resistance, so
It is considered preferable.

As an element that detects dregs, Yani! 11. Due to its simplicity and compatibility with microprocessors, devices that utilize changes in electrical conductivity due to chemical adsorption of gases in metal oxide semiconductors are often used.

Materials include 5no2, ZnO, etc., but these have similar sensitivity to each flammable machine gas, making it difficult to selectively detect alcohol residue.

Furthermore, there has been no one that detects humidity and gas with a one-to-one integrated element, and has both stable humidity-sensitive characteristics and gas-sensitive characteristics with high sensitivity to alcohol, high selectivity, and fast response speed.

The present invention has been made in order to solve the above problems, and provides a gas- and humidity-sensitive element that selectively detects oHloo% relative humidity and alcohol gas with high sensitivity using one integrated constant element. It is an object.

This invention detects humidity using an apatite ceramic material, and detects alcohol gas using a metal oxide between separated electrodes provided on an element substrate made of the apatite ceramic material. Furthermore, the separation electrode is formed by baking ruthenium oxide, which helps increase the sensitivity to alcohol gas.

The gas-sensitive and humidity-sensitive element of the present invention has an electrical resistance at a relative humidity of 0-=100% or an alcohol gas concentration of 0-3.
000 ppm, which makes a big difference.

By measuring the electrical resistance value, relative humidity or alcohol gas can be easily detected.

The details of this invention will be explained below using examples.

Example I Hydroxyapatite powder substituted with 10% of C& 1rIJa was made into a 4 fin x 4 fin size and 0.8 inch thick.

350 k5+/L:i! Molded at a pressure of 110
6 hours at 0℃.

Baking in air. Polish this 1 to a thickness of 250μ,
Separate electrodes (21, (31 (first and third electrodes)) made of RuO2 paste, as shown in the sintered body (1) in FIG.

Further, on the back side, as shown in FIG. 2, an electrode (4) (second electrode) made of RuO2 paste is screen printed on the entire surface. Next, separated electrodes 12+, + with a spacing of 250μ
31 Screen print titanium oxide TlO2 paste using T-squeezing ○ TlO2 paste is prepared by baking 1kt of reagent grade powder in air at 00°C for 1 hour, crushing 1, passing through a 400 mesh sieve, and adding butyl calpitol. It will be done. After printing on TlO21, lead wires (61, (71
, (8) and bake at 800℃ for 10 minutes. The electrode formed in the above manner becomes a porous surface electrode, and humidity easily reaches the sintered body through the electrode. (
In 1), the element substrate is made of a hydroxyapatite moisture-sensitive ceramic material. (5) It is a bee lO2 gas-sensitive material. When detecting gas, it is necessary to keep the entire element at a temperature of 200° C. or higher. Therefore, a Kanthal wire coil heater should be provided around the element shown in Fig. 1.2, or a solid RuO
Two lead wires may be attached to the two electrodes to serve as both a heater and a moisture-sensitive electrode.

Using the gas- and humidity-sensitive element manufactured as described above, measurements shown in FIGS. 3 and 5 are carried out.

FIG. 3 shows the moisture sensitivity characteristics at 25°C.

The measurement was performed by short-circuiting electrodes +21 and (311) and applying an IV, 50 Hg sine wave between this and electrode (4).

Although the voltage may be applied between one electrode and the electrode (4) without shorting the electrodes (21, +31), the measured resistance increases.

As shown in the figure, the electrical resistance changes by more than 4 orders of magnitude at relative humidity (1-100%), and is extremely sensitive.Also, even if it is left in the laboratory for 6 months with or without tV energization, the characteristics change. was within the measurement error and was very stable.This is a feature not found in other ceramic humidity sensors.The response was also 2-
It's fast at 15 seconds.

FIG. 4 shows the gas sensitivity characteristics when the element temperature is changed. Measure the resistance between electrodes +21, (a). Ql) is ethanol o ppm in air, a7Ja ethanol 100 ppm. As shown in the figure, the conventional 5n02 series.

The sensitivity of the ZnO-based sensor at 100 ppm of ethanol.

The sensor according to the present invention exhibits about 10 times the sensitivity compared to the sensor which was 15-2 times as sensitive. however.

The sensitivity here is at ethanol Oppm, i.e.
This is the ratio Ra,/Rg between the resistance value Ra in the atmosphere and the resistance value Rg in 1100 ppp of ethanol. The response to ethanol O→1100pp is 1 second, which is very fast.

Figure 5 shows propane*H2*OO*ethanol 10 each
With a sensitivity S of 0 ppm, the element temperature is 450°C.

As you can see from the figure, propane, H2, CO, etc., show little sensitivity.

For methanol, isopropyl alcohol, etc.
It showed almost the same sensitivity as ethanol.

Note that since apatite has a high alcohol adsorption property, it is highly likely that apatite also contributes to high sensitivity and high selectivity.

Example 2 The first half was manufactured under the same conditions as Example 1, but the second half was different in the formation process of the gas-sensitive material. That is, the paste for forming the gas-sensitive material is a reagent-grade niobium oxide Nb2O5 powder i 10
The product was baked at 00℃ for 1 hour in the air, crushed, passed through a 400 mesh sieve, and added with butyl calpitol. +61, +71,
Attach +81 and bake at 800℃ for 10 minutes. At this time (11 is hydroxyapatite moisture-sensitive ceramic, (2),
(31, (41 is an electrode made of RuO2, (5) is 1J
b205 gas sensitive material.

Figure 6 shows a gas- and humidity-sensitive element using Nb2O5$ gas material.
Figure 8, #! where the measurements shown in Figure 7 were carried out. FIG. 7 corresponds to FIGS. 4 and 5 of Example AJ. In this case, the ethanol sensitivity is about 10 times higher.

The response speed for ethanol O → 100 ppxn is very fast at 1 second. The element temperature in the measurement shown in Figure 7 was 390°C.
It is. Ethanol is shown as a representative.

It shows similar sensitivity to other alcohols such as methanol and isopropyl alcohol.

Note that the measurement results corresponding to FIG. 3 of Example 1 were the same in Example 2 as well.

Description is omitted.

Example 3 The first half was manufactured under the same conditions as Example 1, but the process of forming the gas-sensitive material in the second half was different. That is, the paste for forming the gas-sensitive material is made by passing reagent special grade tin oxide 5N02 powder through a 400 mesh sieve, and then adding butyl calpitol.
After screen printing the created 5no2 paste at the same position as in Example 1, lead wires (6), (71, (81)
Add k.

Bake at 800℃ for 10 minutes. At this time (11 is hydroxyapatite moisture-sensitive ceramic, (2), +3),
+4) is an electrode made of RuO2, and (5) is a 5no2-sensitive waste material.

The measurements shown in FIGS. 8 and 9 were carried out using a gas-sensitive moisture sensing element using a SnO2 gas-sensitive material. FIGS. 8 and 9 correspond to FIGS. 4 and 5 rc of Example 1. . In this case, the ethanol sensitivity is approximately 30 times higher.

The response speed at ethanol 0→10G ppm is very fast at 1 second. The element temperature in the measurement shown in FIG. 9 was 300°C. Ethanol is shown as a representative.

It shows similar sensitivity to other alcohols such as methanol and isopropyl alcohol.

Note that the measurements corresponding to FIG. 3 of Example 1 had the same measurement results in Example 3 as well.

Description is omitted.

Example 1 The first half is manufactured under the same conditions as Example 1, but the process of forming the gas-sensitive material in the second half is different. That is, the paste for forming the gas-sensitive material is made by passing reagent-grade zinc oxide ZnO powder through a 400-mesh sieve and adding temporary butyl calpitol. After printing, connect the lead wires (61, (7), (81k)
Bake at 800℃ for 10 minutes. At this time (1)
is hydroxyapatite moisture-sensitive ceramics, +21, (
3), +4) are electrodes made of RuO2, (5)i
It is a ZnO gas-sensitive material.

A gas-sensitive moisture sensing element using ZnO gas-sensitive material, Fig. 10,
10 and 11, in which the measurements shown in FIG. 11 were carried out, correspond to FIGS. 4 and 5 of Example 1. In this case, the ethanol sensitivity is about 30 times, and the ethanol 0 → 100 M
The response speed f at lm is very fast at 1 second. The element temperature WjL in the measurement shown in FIG. 11 is 450°C. Ethanol was used as a representative example, but other alcohols such as methanol and isopropyl alcohol have the same sensitivity as #1.
Show the IL. Note that the measurement corresponding to FIG. 3 of Example 1 had the same measurement results in Example 4, so the description thereof will be omitted.

Example 1 The first half was manufactured under the same conditions as Example 1, but the second half was different in the formation process of the gas-sensitive material. In other words, the paste for forming the gas-sensitive material is oxalate obtained by the coprecipitation method at 11,000°C.
Mg-Fet5Alq-504 paste made by adding butyl calpitol to the powder that was baked in the atmosphere for an hour, crushed and passed through a 400 mesh sieve) 1 After screen printing in the same position as in Example 1, lead wires. (el,
+71, (s)' and bake at 800℃ for 10 minutes. At this time (t+h hydroxyapatite moisture-sensitive ceramics, (2+, +31, +4 are electrodes made of RuO2, (51f@MgFe15A1o, 504
It is a gas-sensitive material.

The measurements shown in FIGS. 12 and 13 were carried out using a gas-sensitive moisture-sensitive element using MgFe1,5AI0.504 gas-sensitive material. Corresponds to the diagram. In this case, the ethanol sensitivity is about 10 times,
The response speed for ethanol O → 1100 pp is extremely fast at 2 seconds. Element temperature iJ in the measurement of Fig. 13 250
It is ℃. Although ethanol is shown as a representative example, other alcohols such as methanol and inglobil alcohol show similar II&degree. Note that the third example of Example 1
The measurement results corresponding to the figures were the same in Example 5, so their description will be omitted.

Used for the above ten MgFe1,5Alo, so4 1. f
r: -F, AI' In the above examples, hydroxyapatite was used as the apatite, but other apatites may be used.

In other words, hydroxyl groups are replaced with halogens, and calcium is replaced with strontium or barium.

Avatatra may be used instead of lead or the like.

Figure 1.2 shows a plate-shaped gas-sensitive and moisture-sensitive element, but it is made into a cylinder, with electrodes coated all over the inner surface, 11 electrodes separated on the outer surface, and a gas-sensitive paste between the 9 electrodes. You can also paint it.

As described above, the present invention provides an element substrate made of apatite ceramic, and a first element substrate provided on the element substrate with the apatite ceramic interposed therebetween. A second electrode, a third electrode separated from the first electrode and provided on the element substrate, a metal having a sensitivity to alcohol, a third electrode in contact with the first and third electrodes and provided between the first and second electrodes. Since it is a dust-sensitive moisture-sensitive element equipped with an oxide, it is one integrated element.
Relative humidity of 0-=100% and alcohol gas can be selectively detected with high sensitivity.

[Brief explanation of the drawing]

FIGS. 1 and 2 are perspective views showing the structure of an embodiment of the present invention, with FIG. 1 showing its front surface and FIG. 2 showing its back surface. Third
The figure shows humidity sensitivity 11 of this invention? Characteristic curve diagrams showing notes, Figures 4, 6, 8, 10 and l! 12 is a characteristic curve diagram showing the temperature dependence of the gas-sensitive characteristic VC of each embodiment of the present invention, FIG. 5, FIG. 1, FIG. 9, and FIG.
1 and 13 are percentage graphs showing the sensitivity to various gases in each example of the present invention, respectively. In the figure, (1) is an element substrate made of moisture-sensitive ceramics. +21, (3) and +41 are the first electrodes, respectively.
．． Third. ○(5) corresponding to the second electrode is a sensitive material, (
61, (71, (s+ is a lead wire. The same reference numerals in the figures indicate the same - or corresponding parts.
Shin Kuzuno - Fig. 1 Fig. 2 A : c d ”” C d Fig. 6 Fig. 10 Fig. 12 Fig. 1 degree (°C) Fig. 11 Figure 13 2, Dimension Name: Gas-sensing temperature-sensing element 3 To the representative of the person making the amendment: Hitoshi Katayama, Department 4: Attorney Column for detailed description of the invention in the specification subject to the amendment and Drawing 1: Contents of the amendment ( 1) Insert "foul-smelling gas" before "alcohol gas" on page 2, line 2 and page 3, line 19 of the BA specifications. (2) Insert "humidity sensitivity," on page 11E2, line 20 of the BA specifications. ”, the next K “
and odor gas. (3) "Page 3, line 5 and page 12, line 1s"
"Relative humidity" is followed by "and methyl mercaptan (OH
EIH) and a malodorous gas such as hydrogen sulfide (H2S). (4) On page 3, line 11, K before “alcohol gas”
Insert foul-smelling gas and '. (5) Insert "foul-smelling gas concentration" after "or" on page 3, line 16. (6) Next to “ethanol” on page 6, line 16.
, ``, Insert OH8H, H28J. (7) Correct each of Figures 5, T, 9, 11, and Engraved Figure 13 of the drawings as shown in the attached sheet. 7. Correct the list of attached documents. Later Figure 5, Figure T, Figure 9, Figure 11 and Figure 1
3 Drawings showing Figure 1 or more 2 Name of the invention Gas temperature sensing element 3 Relationship to the case of the person making the amendment Patent applicant address 2-3 Makafuse-chome, Maruno, Chiyoda-ku, Tokyo ÷
Sea Name (601) Mitsubishi Electric Co., Ltd. Representative Katayuni 8th Department, 10th Agent IT Address 2, Marunokakaze-chome, Chiyoguchi 1-ku, Tokyo
No. 30 % Percentage of the specification to be amended Claims and Detailed Description of the Invention column and Drawing 1 Contents of the amendment (star) The Claims column of the specification is revised by adding it to the attached sheet. (2) r 5 D HfJ on page 5, line 13 of the specification
rsogg”. ) Same, 1g page 12, line 11 - same page, line 16 “
"Apatite ceramics..." is corrected as follows. "A device substrate made of apatite ceramics, a first and second electrode provided on the device substrate with the apatite ceramic interposed therebetween, a third electrode separated from the first electrode and provided on the device substrate - the first electrode and the third electrode." Figures 1 and 2 of the drawings are corrected as shown in the attached sheet. 1. List of Attached Documents (1) Amended Scope of Claims A document stating 1
(2) Drawings (Fig. 1, Fig. 2) One or more copies each Claims + 1 + Made of apatite ceramics Toru Senki;
A first plate provided on the element substrate with the apatite ceramic interposed therebetween. a second electrode, a third electrode separated from the first electrode and provided on the element substrate, a first electrode in contact with the first electrode and the third electrode;
A gas-sensitive and moisture-sensitive element comprising a metal oxide sensitive to alcohol provided between an electrode and a third electrode. (2) The gas- and moisture-sensitive element according to claim 1, wherein the metal oxide is one of titanium oxide, niobium oxide, soot oxide, #zinc oxide, and magenium ferrite. (3) The gas- and humidity-sensitive element according to claim 1 or 2, wherein the electrode is a porous surface electrode. (4) First. The third electrode is made by baking ruthenium oxide onto the element substrate.Claim 1: Figure 1: Figure 2

Claims (1)

[Claims] (1) An element substrate made of apatite ceramics. A first plate provided on the element substrate with the apatite ceramic interposed therebetween. 2i-th [pole, a third electrode provided on the element substrate apart from the first electrode; Gas-sensitive and moisture-sensitive element equipped with a metal oxide having a temperature of 1 and 20% with respect to alcohol, which is in contact with a first electrode and a third electrode and provided between the first and second electrodes - (2) The metal oxide is titanium oxide , niobium FII, tin oxide, zinc oxide, and magnesium ferrite. (3) The gas- and moisture-sensitive element according to claim 1 or 2, wherein the electrode is a porous surface electrode. 141@2. 31st [Claims 1 to 23 in which the pole is made by baking ruthenium oxide on the element substrate]
The gas- and moisture-sensitive element described in .