Miniature Gas Sensors Heads and Gas Sensing Devices for Environmental Working Conditions - A Review

Abstract

There are many types of gas sensors. The paper presents the group of miniature gas sensor heads that may find applications in gas sensing devices oriented to work in environment conditions. These conditions in the near Earth surface are described as partial gases concentrations including highly varied concentrations of water vapor, atmosphere temperature and pressure as well as wind speed. The miniature gas sensors heads based on different sensing principles and systems of sensing devices are discussed. Sensitivity and selectivity of heads and devices is discussed in the context of used technology. Nowadays, it seems that single miniature gas sensing head is characterized by too low sensitivity or to high cross-sensitivity to other gases and sensitivity to an environment parameters. Therefore sensing device should be prepared from set of miniature gas sensor heads, a gas sampling control module, as well as digital measurement data processing and control. The multiplication of heads in sensing device in homogenous set is used mainly for increase of sensitivity. While cross-sensitivity of sensing device is improved by hardware set of different type miniature gas heads or by