Design Of Electronic Nose Chambers Based Computational Fluid Dynamics

Arrays of gas sensors,which are the core of the electronic nose(e-nose)system,are arranged in the measurement chamber.Since the response of the sensor is affected by the concentration of odor on the surface of the sensor and the morphology of flow field of the airflow,referring to the influence of the nasal structure on the flow field of the airflow,it can be inferred that the structure of the e-nose chamber has an important impact on gas sensing.Therefore,the excellent structure design of chamber can improve the response and recovery of the sensor array,further improving the performance of the e-nose system.The objective of this paper is to design a novel and superior e-nose chamber based on computational fluid dynamics(CFD)simulations in order to increase the response intensity of the sensor array,reduce response time and recovery time of the sensor array.In addition,the influence of chamber structure on sensing performance is explored through simulation and experimentation,and it is hoped to establish a relationship between chamber structure,carrier air flow field,odor concentration field and sensor performance.The main research contents and achievements of the paper are as follows:Based on the Navier-stokes equation describing the carrier gas field,the convective diffusion equation describing the odor concentration field,the dilute substance hypothesis,the coupling theory and finite element theory of the flow field and the concentration field,the mass transport model of odor in the electronic nose chamber is established.The relationship between the carrier gas flow field,the odor concentration field and the chamber structure is also established.COMSOL is used to simulate the steady-state flow field of the carrier gas in the chamber and the transient concentration field of the odorous substance.The velocity distribution near the surface of the sensor array,the velocity distribution and concentration distribution of the longitudinal section in the chamber,the pressure distribution and concentration distribution of the sensor surface,the streamline distribution in the chamber and the concentration curve of the sensor surface are obtained.The physical chamber and humidity sensor were made,and the prepared sensors were first calibrated,and then the calibrated sensors were arranged in the e-nose chamber.Through various humidity measurement experiments,the distribution and magnitude of the response intensity,response time,recovery percentage,maximum first derivative of the response stage and absolute value of the minimum first derivative of the recovery stage of the sensor array in different chambers were compared.The connection between the chamber structure and the sensor performance was finally established.The results of simulation and experiment are discussed,and the connection between chamber structure,carrier gas flow field,odor concentration field and sensor performance were established.The concentration distribution on the surface of the sensor array given by the simulation was consistent with the concentration distribution obtained by the experiment,which confirms the identity of each position in the e-nose chamber.