Research And Design Electronic Nose Based On Embedded System

Electronic nose is the simulation of human and other mammalian olfactory system , identifying and assorting the substances according to the type of smell .It has the advantages of easy sample handling, effective identification, quick detection, non-destructive and so on. With the development of electronic nose technology, it has been widely used in the fields such as tobacco, food, medicine, environmental monitoring , security and so on.However, the commercial electronic nose appeared on the market is often to work based on PC .The large size and high power consumption can not meet the real-time test requirements of mining site. This research developed the electronic nose system based on embedded system, trying to resolve the shortage of e-nose system's large size and high power consumption. We design two kinds of systems for different applications: electronic nose system on desk based on embedded systems and handheld electronic nose system based on ARM7 +μC/OS-Ⅱ.Firstly, this paper describes the design of the sensor array, which includes the selection of gas sensor and calibration of some sensors. Selecting appropriate sensors to compose the sensor array can detect the most gas types with the least sensors, also it can reduce data redundancy and the cost of system.Secondly, the article introduces the design of electronic nose on desk based on embedded systems. This kind of electronic nose system consists of three measurement and control circuit based on MSP430F169 and one embedded tablet PC. Three measurement and control circuit respectively complete the acquisition and processing of the signals of eight semiconductor gas sensors, three electrochemical sensors, one PID sensor, one carbon dioxide sensor, one oxygen sensor and the five emperature and humidity sensor. Besides, they should control the gas flow path valve . Measurement and Control circuit complete the control commands and sensor data transmission by the access to embedded tablet PC through the RS485 circuit.Thirdly, the article introduces the hand-held electronic nose system, which consists of sensors signal acquisition circuit based on MSP430F169 and embedded system based on ARM7 +μC/OS-Ⅱ. The signals of three semiconductor gas sensors or three electrochemical sensors or one PID and temperature and humidity sensors go into the embedded system after the condition of the collection circuit, achieving the functions of data stored, real-time display ,interactive and so on .In this paper, we also do some applied experimental test of the systems developed.The freshness of pork and other agricultural products was tested by the systems. The experimental observations and data analysis show that two sets of systems developed are able to meet the design objectives basically .