Claims
- 1. A method of detecting environmental gaseous products in a gaseous sample comprising contacting a gaseous sample suspected of containing environmental gaseous products with a sensing surface of a dielectric material having a surface resistivity at least equal to 1.times.10.sup.10 ohms per square centimeter and a bulk resistivity of 1.times.19.sup.12 ohm-cm at 50% RH relative humidity and having dispersion bonding forces and minimal dipole hydrogen bonding forces by passing said sample through a free spaced formed by said sensing surface formed by said dielectric material and shield electrode as a reference electrode, holding said shield electrode at a fixed reference potential during the passing of said sample through said free space and thereby reacting said gaseous products with said dielectric material, generating a detectable electrical output potential from said reaction, amplifying said electrical output by passing said output through a high impedance amplifier thereby generating an amplified signal and transmitting said amplified signal to a detecting device for indicating the presence of said gaseous products.
- 2. The method of claim 1 wherein said surface is formed of dielectric material selected from the group consisting of polytetrafluoroethylene (TFE), perfluoroalkoxy (PFA), fluorinated ethylene propylene (FEP), polystyrene, polyethylene, polyester, polyterephthalate, polyimide and polysulfone.
- 3. The method of claim 1 wherein said surface is formed of polytetrafluoroethylene (TFE).
- 4. The method of claim 1 wherein said surface is formed of polystyrene.
- 5. The method of claim 1 wherein said surface is formed of polyethylene.
- 6. The method of claim 1 wherein said surface is formed of perfluoroalkoxy (PFA).
- 7. The method of claim 1 wherein said surface is formed of fluorinated ethylene propylene (FEP).
- 8. The method of claim 1 wherein said surface is formed of a material including a predominate portion selected from polytetrafluorethylene (TFE), perfluoroalkoxy (PFA), fluorinated ethylene propylene (FEP), polystyrene and polyethylene.
- 9. The method of claim 1 including the forming of the ground shield as an outer perforated enclosure with said probe means mounted within the enclosure.
- 10. In the method of claim 1 wherein said dielectric material surface resistivity is in excess of 1.times.10.sup.15 ohm/square and said bulk resistivity is in excess of 1.times.10.sup.15 ohm-cm at 50%RH.
- 11. The method of claim 1 including intimately attaching said material as a coating to a conductive supporting base member.
- 12. The method of claim 11 including adhesively bonding the dielectric material to the base member.
- 13. The method of claim 12 including use of a silicone contact adhesive to bond said material to the base member.
- 14. In the method of claim 1 wherein said dipole-hydrogen bonding force is less than 5.0 ergs/cm.sup.2.
- 15. The method of claim 14 including use of said material having a dipole-hydrogen bonding force of less than 1 ergs/cm.sup.2.
- 16. A method of detecting environmental gaseous products in a gaseous sample comprising contacting a gaseous sample suspected of containing environmental gaseous products such as combustion products with a capacitance sensing surface of a dielectric material selected from the group consisting of polytetrafluoroethylene (TFE), perfluoroalkoxy (PFA), fluorinated ethylene propylene (FEP), polystyrene, and polyethylene by passing said sample through a free spaced formed by said sensing surface formed by said dielectric material and a grounded shield electrode as a capacitance reference electrode spaced to form a sensing capacitor unit, holding said shield electrode at a reference ground potential during the passing of said sample through said free space and thereby reacting said gaseous products with said dielectric material, generating a detectable electrical output potential from said reaction, amplifying said electrical output by passing said output through a high impedance amplifier thereby generating an amplified signal and transmitting said amplified signal to a detecting device for indicating the presence of said gaseous products.
- 17. The method of claim 16 including forming of the probe means as a disc-like element mounted within the ground shield means and having said material on opposite sides of the first electrode means.
Parent Case Info
This is a continuation application, of application, Ser. No. 702,918, filed July 6, 1976 now abandoned.
US Referenced Citations (12)
Continuations (1)
|
Number |
Date |
Country |
Parent |
702918 |
Jul 1976 |
|