Combustion detecting device using metallo-phthalocynine semiconductor and process of preparing same

A device for detecting combustion products and effects resulting from combustion which comprises an insulating substrate, spaced conducting electrodes deposited on said substrate and a thin uniform coating of an amphorphous or crystalline metallo-phthalocyanine composition deposited on said substrated between said electrodes, said composition being selected from the group consisting of Fe.sub.II Pc, Fe.sub.III Pc, Ni.sub.II Pc, Cu.sub.II Pc and CuPc-CCl.sub.4 where Pc represents phthalocyanine, said coating being prepared by mixing said metallo-phthalocyanine composition in powder form with a carbon-containing liquid solvent selected from the group consisting of carbon tetrachloride, ether and acetone, allowing said metallo-phthalocyanine composition to remain in said solvent for a period of time to modify its initial phthalocyanine molecule, stirring said mixture to obtain a homogeneous suspension of the modified metallo-phthalocyanine composition powder in said solvent, applying a thin uniform coating of said suspension in a selected pattern on said insulating substrate and drying said coating to form on said substrate a resistance element having a resistance of 10.sup.6 ohms to 10.sup.11 ohms, said substrate having a resistance at least 10 times that of said resistance element, a finely ground buffer selected from the group consisting of silicagel and a molecular sieve being saturated with water and mixed with said metallo-phthalocyanine composition before said composition before said composition is applied to said substrate.

Process of making a device for detecting combustion products and effects resulting from combustion which comprises:

• preparing a composition of metallo-phthalocyanine, in amorphous or crystalline form, selected from the group consisting of Fe.sub.II Pc, Fe.sub.III Pc, Ni.sub.II Pc, Cu.sub.II Pc, CuPc-CCl.sub.4 where Pc represents the monomeric phthalocyanine group,
• mixing said metallo-phthalocyanine composition in powder form with a carbon-containing liquid solvent selected from the group consisting of carbon tetrachloride, ether and acetone, allowing said metallo-phthalocyanine composition to remain in said solvent for a period of time to modify its initial phthalocyanine molecule and stirring said mixture to obtain a homogeneous suspension of the modified metallo-phthalocyanine composition powder in said solvent,
• applying a thin uniform coating of said suspension in a selected pattern on an insulating substrated and drying said coating to form a resistance-element having a resistance of 10.sup.6 ohms to 10.sup.10 ohms, and
• providing electrical contacts for connecting said resistance element in an electrical circuit for measuring the electrical resistance of said resistance element and thereby detecting change in electrical resistance produced by exposure to combustion products and effects resulting from combustion,
• a finely ground molecular sieve being introducted into the mixture of said metallo-phthalocyanine and carbon-containing solvent to reduce sensitivity of the device to atmospheric pressure.