Abstract: A transcutaneous gas sensor for application to the skin of a patient for bloodless measurement of a partial gas pressure comprises a separable sensing cell and a circumferential heater, the heater being in direct thermal contact with the skin of the patient but not in contact with the permeable sensing face of the sensor cell. A differential temperature measuring thermocouple is utilized to monitor the temperature of the patient's skin and the temperature of the heater to provide a warning of a decrease in local perfusion in the area of the sensing cell.

Abstract: The embodiment of the pollution monitor described in the specification uses the principle of ultraviolet-induced fluorescence to detect and measure gaseous pollution in air, smokestack exhaust and other fluids. Improved calibration or standardization is effected by the use of one or more calibration cells in which a non-gaseous material simulates the fluorescence of the gaseous species under investigation, by scattering the incident ultraviolet light into a spectral region similar to that of the fluorescence of the gaseous species. Examples of suitable materials have been found to be aluminum, gold, platinum and molybdenum, all of which scatter light in the appropriate spectral region at a level which stays substantially constant with time.In the preferred embodiment, the sample cell and the calibration cells are all formed in a single cell block by drilling holes into solid bar material which holes function as the individual cell cavities.