GB2186087A - Heterocyclic semiconductor gas sensors - Google Patents
Heterocyclic semiconductor gas sensors Download PDFInfo
- Publication number
- GB2186087A GB2186087A GB08602358A GB8602358A GB2186087A GB 2186087 A GB2186087 A GB 2186087A GB 08602358 A GB08602358 A GB 08602358A GB 8602358 A GB8602358 A GB 8602358A GB 2186087 A GB2186087 A GB 2186087A
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- United Kingdom
- Prior art keywords
- sensor according
- compound
- atoms
- different
- film
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- 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.)
- Granted
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- 239000004065 semiconductor Substances 0.000 title claims abstract description 8
- 125000000623 heterocyclic group Chemical group 0.000 title 1
- 150000001875 compounds Chemical class 0.000 claims abstract description 22
- 239000007789 gas Substances 0.000 claims abstract description 18
- 125000004435 hydrogen atom Chemical group [H]* 0.000 claims abstract description 9
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims abstract description 8
- 229910052727 yttrium Inorganic materials 0.000 claims abstract description 5
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 4
- 230000002209 hydrophobic effect Effects 0.000 claims abstract description 3
- 239000000126 substance Substances 0.000 claims abstract description 3
- 239000000758 substrate Substances 0.000 claims description 10
- 125000004122 cyclic group Chemical group 0.000 claims description 6
- 125000001997 phenyl group Chemical group [H]C1=C([H])C([H])=C(*)C([H])=C1[H] 0.000 claims description 5
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 4
- JUJWROOIHBZHMG-UHFFFAOYSA-N Pyridine Chemical compound C1=CC=NC=C1 JUJWROOIHBZHMG-UHFFFAOYSA-N 0.000 claims description 4
- 125000000217 alkyl group Chemical group 0.000 claims description 4
- MWPLVEDNUUSJAV-UHFFFAOYSA-N anthracene Chemical compound C1=CC=CC2=CC3=CC=CC=C3C=C21 MWPLVEDNUUSJAV-UHFFFAOYSA-N 0.000 claims description 4
- 125000004429 atom Chemical group 0.000 claims description 4
- GDTBXPJZTBHREO-UHFFFAOYSA-N bromine Chemical compound BrBr GDTBXPJZTBHREO-UHFFFAOYSA-N 0.000 claims description 4
- 125000004432 carbon atom Chemical group C* 0.000 claims description 4
- 125000004433 nitrogen atom Chemical group N* 0.000 claims description 4
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 3
- 238000001074 Langmuir--Blodgett assembly Methods 0.000 claims description 3
- UFWIBTONFRDIAS-UHFFFAOYSA-N Naphthalene Chemical compound C1=CC=CC2=CC=CC=C21 UFWIBTONFRDIAS-UHFFFAOYSA-N 0.000 claims description 3
- 229910052799 carbon Inorganic materials 0.000 claims description 3
- 229910052802 copper Inorganic materials 0.000 claims description 3
- 239000010949 copper Substances 0.000 claims description 3
- -1 nitro, carboxy Chemical group 0.000 claims description 3
- ZCYVEMRRCGMTRW-UHFFFAOYSA-N 7553-56-2 Chemical group [I] ZCYVEMRRCGMTRW-UHFFFAOYSA-N 0.000 claims description 2
- KZBUYRJDOAKODT-UHFFFAOYSA-N Chlorine Chemical compound ClCl KZBUYRJDOAKODT-UHFFFAOYSA-N 0.000 claims description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 2
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical group [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims description 2
- 150000001298 alcohols Chemical class 0.000 claims description 2
- 125000002877 alkyl aryl group Chemical group 0.000 claims description 2
- 150000001408 amides Chemical class 0.000 claims description 2
- 125000003710 aryl alkyl group Chemical group 0.000 claims description 2
- 229910052794 bromium Inorganic materials 0.000 claims description 2
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 claims description 2
- 125000003262 carboxylic acid ester group Chemical class [H]C([H])([*:2])OC(=O)C([H])([H])[*:1] 0.000 claims description 2
- 229910052801 chlorine Inorganic materials 0.000 claims description 2
- 239000000460 chlorine Substances 0.000 claims description 2
- 229910017052 cobalt Inorganic materials 0.000 claims description 2
- 239000010941 cobalt Substances 0.000 claims description 2
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims description 2
- 125000004093 cyano group Chemical group *C#N 0.000 claims description 2
- 125000004185 ester group Chemical group 0.000 claims description 2
- 239000001257 hydrogen Substances 0.000 claims description 2
- 229910052739 hydrogen Inorganic materials 0.000 claims description 2
- 229910052740 iodine Inorganic materials 0.000 claims description 2
- 229910052742 iron Inorganic materials 0.000 claims description 2
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical group [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 claims description 2
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 claims description 2
- 229910052757 nitrogen Inorganic materials 0.000 claims description 2
- 229910052702 rhenium Inorganic materials 0.000 claims 1
- 229910052751 metal Inorganic materials 0.000 abstract description 7
- 239000002184 metal Substances 0.000 abstract description 7
- 239000010408 film Substances 0.000 description 18
- 238000000151 deposition Methods 0.000 description 6
- 238000000034 method Methods 0.000 description 6
- 230000008021 deposition Effects 0.000 description 5
- 125000001424 substituent group Chemical group 0.000 description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 3
- 239000004020 conductor Substances 0.000 description 3
- HEDRZPFGACZZDS-UHFFFAOYSA-N Chloroform Chemical compound ClC(Cl)Cl HEDRZPFGACZZDS-UHFFFAOYSA-N 0.000 description 2
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- 239000002356 single layer Substances 0.000 description 2
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 description 1
- JBRZTFJDHDCESZ-UHFFFAOYSA-N AsGa Chemical compound [As]#[Ga] JBRZTFJDHDCESZ-UHFFFAOYSA-N 0.000 description 1
- 229910001218 Gallium arsenide Inorganic materials 0.000 description 1
- 230000001476 alcoholic effect Effects 0.000 description 1
- 239000004411 aluminium Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 239000005030 aluminium foil Substances 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000007598 dipping method Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 230000005669 field effect Effects 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 229910052736 halogen Inorganic materials 0.000 description 1
- 150000002367 halogens Chemical class 0.000 description 1
- 125000005842 heteroatom Chemical group 0.000 description 1
- 150000002391 heterocyclic compounds Chemical class 0.000 description 1
- 230000005660 hydrophilic surface Effects 0.000 description 1
- 125000001165 hydrophobic group Chemical group 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 239000012212 insulator Substances 0.000 description 1
- 230000002452 interceptive effect Effects 0.000 description 1
- 125000001449 isopropyl group Chemical group [H]C([H])([H])C([H])(*)C([H])([H])[H] 0.000 description 1
- 239000010410 layer Substances 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 229920001296 polysiloxane Polymers 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000003908 quality control method Methods 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 238000010992 reflux Methods 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- 230000001960 triggered effect Effects 0.000 description 1
- 238000002061 vacuum sublimation Methods 0.000 description 1
- 230000000007 visual effect Effects 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
- G01N27/12—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid, for detecting components in the fluid
- G01N27/125—Composition of the body, e.g. the composition of its sensitive layer
- G01N27/126—Composition of the body, e.g. the composition of its sensitive layer comprising organic polymers
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
Abstract
An organic chemical semi-conductor gas sensor comprises a film of 1 to 50 molecules thick of a compound of formula I: <IMAGE> in which one of R2 and R3 is hydrophilic and the other is hydrophobic, other R's X's and Y's are specified radicals, and M is a specified metal, preferably nickel, or two hydrogen atoms. The sensors may be incorporated into NOx detectors.
Description
SPECIFICATION
Improvements in gas sensors
This invention concerns improvements in gas sensors, and more especially it concerns improved organic sensors for gases such as NOx.
Reference is made to UK Published Patent Application No. 2,111,987A which discloses certain symmetric heterocyclic compounds as having semi-conductor properties which are effective as gas sensors.
We have now discovered different classes of compounds offer the possibility of improved performance as gas sensors, and novel gas sensors utilising such compounds.
The present invention provides an organic chemical semi-conductor gas sensor comprising a film of 1 to 50 molecules thick of a compound of general formula
in which each of A and B, which may be the same or different, is a carbon atom or a nitrogen atom,
Each R1, R1,, Re, R6,, which may be the same or different, is a hydrogen atom, methyl group or forms part of a condensed six membered ring system,
R2 and R3 are different and one is selected from hydrophilic atoms and groups and the other is selected from hydrophobic atoms and groups.
Each pair of X's and Y's, which may be the same or different, together form an unsaturated ring system selected from phenyl, napthalene, anthracene, 2,3-pyridine and 3,4-pyridine, and phenyl groups which together with adjacent nitrogen atoms and adjacent R1, R,', R6, R6, radicals, form part of a condensed double or triple six-membered ring system, or are hydrogen atoms.
Each R4, R4,, R5, B5,, which may be the same or different, is a hydrogen atom, chlorine, bromine or iodine atom, or a nitro, carboxy, alkyl of 1 to 4 carbon atoms, cyano or ester group, and
M is selected from manganese, iron, cobalt, copper and zinc atoms or may be two hydrogen atoms.
Exemplary molecular structures for use in the present invention include the following:
In the compounds of formula I, it is preferred that each pair of X's and Y's are identical one with another, including substituents, and if substituents are present, it is preferred that these are symmetrically arranged.
The radicals R2 and R3 may be selected from hydrophilic substituents such as acid, including especially carboxy groups, amides, carboxylic acid esters and alcohols, and from hydrophobic groups such as straight or branched chain alkyl, including especially isopropyl, and aralkyl or alkyl aryl, for example, paramethyl phenyl.
It is preferred that the R,, R,', R6, B6,, substituents are identical and are hydrogen.
Certain of the compounds and their preparation have been described in the literature, although they have not been suggested for use in this film semiconductor gas sensors, and the novel compounds may be prepared by analogous methods or by syntheses within the ability of the competent chemist. Reference may be made to Mueller and Woehrle, Markromol. Chem 176 2775-95(1975); Cutler and Dolphin J. Coord. Chem. 6, 59-61 (1976); Guendel and Bohnert,
Z.Nat. 376, 1648-1651 (1982); Phace et al, J. Hetero. Chem. 17, 439-443 (1980), Honeybourne, Inorg. Synth. 1849(1978), etc.
It is preferred to use nickel as the metal M in the selected compound of formula I. Metals may be exchanged or inserted, for example by refluxing using the appropriate metal acetate in a dilute alcoholic solution.
Preferably, the film of the compound of general formula ' is deposited upon a suitable substrate by Langmuir-Blodgett techniques to give a film which is substantially completely ordered on the molecular level. Ordering may be by stacking the largely planar molecules edge-on with respect to the substrate, or parallel to the substrate. The substrate may be an insulator, semi-conductor or conductor, and conductors may be applied to the film by any suitable means to enable a current to be passed across or through said film. The present invention also lends itself to application to an insulated gate field effect transitor, thus to chemically modify its performance in the presence of gases being sensed. Deposition of the film by other techniques such as from the vapour phase, may be used.
It is preferred to use as the substrate a crystal face or optical flat of a material having a highly ordered lattice or a lattice of highly reproducible structure. Silicon or gallium arsenide are particularly preferred substrate materials.
The preferred deposition method by Langmuir-Blodsett technique is suitably carried out by a method derived from that described by Tredgold (Thin Solid Films 113, 115-128). For example, the selected compound of formula 1, in dilute solution in chloroform, is spread on an aqueous sub-phase and compressed. This monolayer is then deposited on the substrate in order to produce an ordered monolayer. Additional ordered layers may be built up by dipping and withdrawing the substrate through the spread organic solution which is supported by a buffered aqueous sub-phase of pH in the region 5-0-6.0 or 7.0 to 8.0, at below room temperature, e.g.
about 10 C, at a sufficiently slow rate to enable additionally deposited monolayers to order up.
The main alternative method of film formation is by vacuum sublimation; it is rather more difficult to control the thickness of the film than with the Langmuir-Blodgett technique, but this can be achieved by suitable batch sizes and quality control. Other methods of film formation may be tried to achieve the best sensor efficiency and stability for any given compound of formula I, including deposition from solution, admixtures with polymers, such as bis-phenyl-apolycarbonate, polymethyl methacylate, or attaching the compound by a polysiloxane.
As previously indicated, a variety of sensor cells may be produced within the scope of the invention. For example in a sandwich cell, the substrate for film deposition is a suiable metal conductor, for example a clean aluminium foil or gold foil. A thin metal top electrode, porous to enable gas diffusion to the film, may be deposited on the film of compound of formula I.
Alternatively, the film of compound I may be deposited upon a silica (eg. quartz) optical flat which has been cleaned by boiling isopropanol and immersion in an acid etch bath, yielding a hydrophilic surface. Electrodes, e.g. of aluminium, copper, platinum or gold, may be applied prior to, or subsequent to film deposition, to contact the film and provide an electrical connection. It is envisaged that the thin film sensors of the present invention may also be manufactured by deposition/etching technology derived from that used for making silicon chip microprocessors.
The sensors of the invention demonstrate significant changes in electrical conductivity upon exposure to gas containing NOx. The gas induced increase in DC current is desirably amplified, preferably using a noise reduction design, and preferably an identical sensor protected from the gas is used as a reference in order to substantially eliminate or compensate for "drift" due to temperature. The sensor may be incorporated into an instrument of hand-held or larger dimensions and NOX concentrations may be displayed by LED, LCD or meter, and/or a visual or audible alarm may be triggered at an appropriate level; alternatively, or in addition, a signal derived from the sensor may be transmitted to a remote monitoring station.
The sensors of the invention incorporate different compounds to those previously disclosed for use in semi-conductor sensors, and the film thickness is a small fraction of that previously recommended, namely about 1 micron. The sensors of the invention offer faster response times because of reduced diffusion times and improved release of the gas being sensed from the molecular matrix.
While reference has been made extensively herein to the sensing of NOx, selection of appropriate compounds of formula I, for example by choosing metals other than nickel, may lead to sensors capable of quantitatively detecting gases such as CO, CH4, H2, N2 04, N2 2, CO2, NH3,
H2S, H2O and halogens. Specificity may be improved by incorporation of a filter of passive or active type to remove potentially interfering gases.
Claims (9)
1. An organic chemical semi-conductor gas sensor containing a film of 1 to 50 molecules thick of a compound of general formula, I
in which each of A and B, which may be the same or different, is a carbon atom or a nitrogen atom,
Each R1, B1,, R6, Rue', which may be the same or different, is a hydrogen atom, methyl group or forms part of a condensed six membered ring system,
R2 and R3 are different and one is selected from hydrophilic atoms and groups and the other is selected from hydrophobic atoms and groups.
Each pair of X's and Y's which may be the same or different, together form an unsaturated ring system selected from phenyl, naphthalene, anthracene, 2,3-pyridine and 3,4-pyridine, and phenyl groups which together with adjacent nitrogen atoms and adjacent R1, B1,, Be, Re' radicals, form part of a condensed double or triple six-membered ring system, or are hydrogen atoms.
Each R4, B4,, Be, Rue', which may be the same or different, is a hydrogen atom, chlorine, bromine or iodine atom, or a nitro, carboxy, alkyl of 1 to 4 carbon atoms, cyano or ester group, and
M is selected from manganese, iron, cobalt, copper and zinc atoms or may be two hydrogen atoms.
2. A sensor according to claim 1, wherein the compound of general formula I is of the structure la, Ib or Ic, hereinbefore defined.
3. A sensor according to claim 1, wherein in the compound each pair of X's and Y's are identical one with another.
4. A sensor according to claim 1, 2 or 3, wherein in the compound the radicals R2 and R3 are selected from carboxy groups, amides, carboxylic acid esters and alcohols and from straight or branched chain alkyl, aralkyl and alkyl aryl.
5. A sensor according to any one of claims 1 to 4, wherein in the compound, each R1, B1,, Re and B6, is hydrogen.
6. A sensor according to any one of claims 1 to 5, wherein in the compound, M is nickel.
7. A sensor according to any one of the preceding claims, wherein the film is deposited on a substrate by the Langmuir-Blodgett technique.
8. A NOx sensing instrument incorporating an organic sensor according to any one of the preceding claims.
9. An organic sensor according to claim 1, substantially as hereinbefore described.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8602358A GB2186087B (en) | 1986-01-31 | 1986-01-31 | Improvements in gas sensors |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8602358A GB2186087B (en) | 1986-01-31 | 1986-01-31 | Improvements in gas sensors |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8602358D0 GB8602358D0 (en) | 1986-03-05 |
| GB2186087A true GB2186087A (en) | 1987-08-05 |
| GB2186087B GB2186087B (en) | 1989-10-25 |
Family
ID=10592272
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8602358A Expired GB2186087B (en) | 1986-01-31 | 1986-01-31 | Improvements in gas sensors |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2186087B (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0332934A2 (en) * | 1988-03-14 | 1989-09-20 | Siemens Aktiengesellschaft | Apparatus for measuring the partial pressure of gases or vapours |
| WO1991007659A1 (en) * | 1989-11-08 | 1991-05-30 | British Technology Group Ltd. | Gas sensors and compounds suitable therefor |
| WO1991007658A1 (en) * | 1989-11-08 | 1991-05-30 | British Technology Group Ltd. | Gas sensors and compounds suitable therefor |
| US5733506A (en) * | 1989-11-08 | 1998-03-31 | British Technology Group, Ltd. | Gas sensors and compounds suitable therefor |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2111987A (en) * | 1981-12-01 | 1983-07-13 | Nat Res Dev | Heterocyclic semiconductors and gas sensors |
-
1986
- 1986-01-31 GB GB8602358A patent/GB2186087B/en not_active Expired
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2111987A (en) * | 1981-12-01 | 1983-07-13 | Nat Res Dev | Heterocyclic semiconductors and gas sensors |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0332934A2 (en) * | 1988-03-14 | 1989-09-20 | Siemens Aktiengesellschaft | Apparatus for measuring the partial pressure of gases or vapours |
| EP0332934A3 (en) * | 1988-03-14 | 1992-05-20 | Siemens Aktiengesellschaft | Apparatus for measuring the partial pressure of gases or vapours |
| WO1991007659A1 (en) * | 1989-11-08 | 1991-05-30 | British Technology Group Ltd. | Gas sensors and compounds suitable therefor |
| WO1991007658A1 (en) * | 1989-11-08 | 1991-05-30 | British Technology Group Ltd. | Gas sensors and compounds suitable therefor |
| GB2239706A (en) * | 1989-11-08 | 1991-07-10 | Nat Res Dev | Gas sensors and compounds suitable therefor |
| GB2239706B (en) * | 1989-11-08 | 1993-05-12 | Nat Res Dev | Gas sensors and compounds suitable therefor |
| US5318912A (en) * | 1989-11-08 | 1994-06-07 | British Technology Group Limited | Gas sensors and compounds suitable therefor |
| US5451674A (en) * | 1989-11-08 | 1995-09-19 | British Technology Limited | Transition metal azatetrabenzoporphyrins useful as gas sensors |
| US5733506A (en) * | 1989-11-08 | 1998-03-31 | British Technology Group, Ltd. | Gas sensors and compounds suitable therefor |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2186087B (en) | 1989-10-25 |
| GB8602358D0 (en) | 1986-03-05 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |