Ratiometric Information Detection And Recognition Technology Based On Electronic Nose Using Surface Acoustic Wave Sensor

The chemical communication widely exists between organic individuals.It is a kind of communication system independent of acoustic wave,light or electric.Mimicking insects chemical communication system and exploring this technology using info-chemical materials as the media have been focused recently.Based on the understanding of insects chemical communication system,artificial chemical communication system,based on electronic nose technology,using plant volatile compounds mixed in ratios has been proposed.After analyzing the chemical structures of the volatile molecules of Rhagoletis pomonella's host plant,the binary mixture of 3-methylbutan-l-of and ethyl acetate has been chosen to be info-chemical media.262MHz surface acoustic wave Rayleigh type gas sensor with ST-cut quartz substrate has been used.To detect the binary mixture,for kinds of polymers,namely,polycaprolactone,polyvinylcarbazole,polyethylene-co-vinyl acetate and polystyrene-co-butadiene,are selected as the sensing materials,which were then spray coated on the surface of the sensor.Then,the artificial chemical communication system consisted of ratio-metric encoding and emitting module,transmission module,and detecting and ratio-metric decoding module has been constructed.The binary mixture of 2 concentrations and 7 ratios totally form 14 different kinds of mixtures of info-chemical media.They are injected with precisely in ratios by the artificial gland,where encoding takes place.Principle component analysis has been performed and successfully demonstrate the capability of the system to separate ratios of different clusters.In many cases,chemical communication system has to be exposed in the ambient,which make the sensor easily adhered and contaminated by the suspended particles in the air.To investigate the influence of the suspended particles to the surface acoustic wave sensor(SAW),a coupled model of particle-SAW has been derived inspired by particle-QCM model.Experimental study has been performed using starch particles,which sizes are in the range of suspended particles.The result shows that,for particles with larger sizes,suspended particulate matter has a weak coupling with surface acoustic wave sensors.SAW measures the contact rigidity coupling interface instead of the mass shift with particles.SAW responses positive frequency shift with a linear relationship to the power of two thirds particles radiusInsects use antennal lobe as olfactory information relay for the signal processing of the ratio-metric info-chemical signals.Based on the understanding of recent research of antennal lobe topology,an artificial antennal lobe network has been built.Although inhibitory/excitation properties of the connection in the network has been revealed,detailed connection strength is still unknown,therefore,4 different strategies of olfactory reception neuron(ORN)-local neuron(LN)has been proposed.Under the frame of symmetric/asymmetric LN-LN connections,the dynamic properties of the network has been analyzed.The result shows that,in the condition of fixed dose,artificial AL network have large encoding capacity over the traditional principle component analysis method,which would benefit the transmission rate of the communication system.