Gas concentration and flow speed measurements using a polymer-based membrane sensor

This contribution presents a polymer-based membrane sensor that is capable of determining simultaneously flow speed and gas concentration of binary gas mixtures. The sensor therefore combines two excitation modes. It consists of an unsymmetrical 1D-resistor array made of platinum. The well defined temperature coefficient of resistance enables to switch between constant temperature and constant power excitation modes of the heating element. The response signal of the downstream temperature sensor allows the gas concentration measurement of a binary gas mixture using constant power excitation mode. A switch to constant temperature excitation allows flow speed measurements. A sinusoidal AC-excitation with a frequency of 1 Hz is chosen to carry out the proof-of-concept.