Study On The Temperature Modulation Feature Of Gas Sensor In Electronic Nose

Along with the quick development of national economy as well as the continuous improvement of living standard, electronic nose has been widely applied in the fields of food industry, environmental test, industrial and agricultural quality control, medical sanitation, etc. Especially for medical diagnoses, according to the osculate connection between ailment and smell, electronic nose can detect special smell and make non-traumatic, quick and simple diagnoses, which has operational significance to the early discovery and early treatment of some serious diseases. Correspondingly, this puts forward higher requirements for electronic nose, which need higher sensitivity and lower detection threshold. Based on a general introduction of electronic nose system, this thesis introduced all kinds of gas sensors used now, and made a thorough analysis on the features of the sensors and sensitivity theory. Theories and experiments have shown that the sensitivity of gas sensors can be effectively improved, the lowest detection threshold can be reduced and the structure of electronic nose system can be simplified by using temperature modulation to dynamically heating gas sensors instead of heating the metal oxide ones in the traditional way. In order to validate the effect of temperature modulation on gas sensor, a set of sensor test system is designed and constructed. It utilizes square wave whose duty ratio can be adjusted to heat the metal oxide sensor TGS822, takes a test of ethanol, and makes analysis with the software Matlab. The results proved that some gas sensor and the tested smell can reach one best duty ratio, which refers to the best working condition, if they combine with respective features. Under this circumstance, the gas sensor can exert the greatest efficiency and the whole function of electronic nose system. can be improved.