Abstract
The switch off concentration phenomena in carbon monoxide oxidation on platinum and the parallel steep variation of resistance or surface potential of thin platinum films are used to develop a carbon detector. Coating the platinum film with an increasing thickness of polytetrafluorethylene (PTFE) makes this switch off point move to increasing CO concentrations. Therefore a series of electrical elements, platinum thin film resistances, platinum M.O.S. diodes or platinum gate M.O.S. transistors covered by calibrated thicknesses of PTFE will switch off at well determined CO concentrations and can continue the basis of a digital detector.