A robust high temperature semiconducting CO sensor
T2005-082 A high-temperature metal oxide semiconductor based gas sensor that is doped with noble metals to increase stability and selectively
Machines that burn fuel for operation require numerous safety features to detect leaks of volatile and toxic gases that can be harmful or deadly to people if inhaled. Of these gases produced during combustion, carbon monoxide (CO) is one of the most important to consider due to its lethal capability and the long-term adverse health effects of non-fatal CO poisoning. In addition to safety requirements, the manufacturing industry monitors CO levels to balance the oxygen (O2) to fuel ratio during combustion. By monitoring CO levels, an ideal balance of O2 to fuel can be maintained during industrial processes which can increase the life of an engine and minimize the pollution produced. When unable to monitor CO levels, manufacturers tend to run lean in order to avoid explosions but this kind of operation can result in engine knocking and the formation of NOx species. Existing gas sensors are made from metal oxide semiconductors (MOS) that usually exhibit low selectivity and respond indiscriminately to a broad spectrum of reactive gases. In addition to an indiscriminate response, state of the art detectors and sensors based on MOS will often exhibit unstable baseline resistance, continuous drift, and poor recovery time. In order to properly monitor the amount of CO present within engines or industrial machinery, a sensor that demonstrates robust performance in high temperature environments and selective detection must be developed.
Researchers at The Ohio State University, led by Dr. Prabir Dutta, have developed a composite sensor that is capable of determining the concentration of CO within a mixture and demonstrates stable high-temperature operation. The composite sensor is MOS-based and its surface is doped with noble metals to improve selectivity and stability. The sensor is able to detect sub-ppm levels of CO within a gas mixture with range extending up to 1,000 ppm. The composite sensor has been demonstrated to provide sensitive, low drift and fast-recovering detection of CO within a high-temperature environment ranging from about 400°C to about 800°C.
- Manufacturing industry monitors
- Automotive sensors
- Commercial safety systems
- Responds to CO levels from 0-1,000 ppm
- Quick recovery times
- Can be used in high-temperature environments (400- 800°C)
- More selective than present gas sensors which respond to almost any reactive gas
- Minimal drift