Design Of Electronic Nose And Electronic Tongue For Environmental Detection

The paper describes the design and implementation of an in-situ electrical tongueused to detect six kinds of trace heavy metals (Zn, Cd, Pb, Cu, As, Hg) in water and aportable electrical nose for flammable gas.The electrical tongue instrument adopts differential pulse stripping voltammetry todetect trace heavy metals in situ and automatically. The instrument can be divided intotwo parts based on function: measurement and control system. The electrochemicalmeasurement system used to perform DPSV measurement is constructed with twoparts, a low-current measurement system consists of low input bias currentoperational amplifier and a high resolution SAR ADC and a potentiostat consists ofhigh resolution DAC and high current buffer amplifier. The control system performsthe functions of measurement, communication and sample's transport. It can limberlyconfigure the parameters such as open/close sequence and delay time of valve andpump, thus analyze sample automatically. The instrument features full automaticmeasurement, wonderful extensibility and high reliability.The electrical nose adopts thermal catalytic sensor for flammable gas's detection.The system based on MSP430 can detect the gas concentration conveniently and inreal time, and be configured by the buttons. The result can be transmitted to PC viaUART for data storage and management. The electrical nose has the functions ofsound and light alarm, voltage monitoring, real-time display with the features of smallsize, high sensibility, quick response and portable.The prototype has been fully checked and the result shows that all aspects ofhardware reach the requirement.