Construction and Testing of a Vapor Sensor Based on Ion Mobility and Gas Flow

摘要

In order to answer the need for low cost gas monitors for use in gas detection applications, a prototype sensor was built on the principle of ion mobility, and the performance of this prototype was evaluated. Ion mobility employed the difference in drift velocity in an electric field of ions formed from different substances. Due to its sensitivity, ion mobility has been used for the monitoring of a number of kinds of pollutants in air for a number of years. The technique was simple as separation of different ions depended on the difference in their drift velocities in air at atmospheric pressure. The ions were measured from the substance of interest at a narrow collector after they had traveled in a vertical direction under the influence of an electric field and in a perpendicular direction using air flow. It was anticipated that ions of different mobilities could be separated in this manner. The sensor functioned as predicted in a qualitative sense. At a given flow rate, response from the device was obtained over a given range of voltages, determined by the flow rate used. The device was very sensitive to flow parameters.