CONDUCTOMETRIC METAL OXIDE GAS SENSORS 161 New Cosmos (www.new-cosmos.com); and others. More details on the companies and sensor products can be found at the listed websites. 9. OUTLOOK FOR THE FUTURE As a conclusion, we note that a number of important achievements have been made in the development of conductometric gas sensors: · Various kinds of gases, including reducing gases (methane, propane, carbon monoxide, ammonia, hydrogen sulfide, etc.), volatile organic compounds (alcohols, ketones, etc.), and oxidizing gases (oxygen, nitrogen dioxide, ozone, etc.) are now detectable. The detection of many toxic and inflammable gases is possible over a large concentration range, including parts per billion. Sensors can be fabricated via many technologies, including ceramics, thick and thin films, as well as micromachining methods. Microfabrication has decreased sensor power consumption down to milliwatts and led to por- table gas-sensing devices for field applications. · · · However, the field of conductometric gas sensors still demands innovations toward better sensing