Research On Electrical Impedance Imaging Hardware Systems

EIT(Electrical Impedance Tomography)has attracted wide publicity in related field,which is a new direction of medical imaging technology.Compared with the existing medical imaging technologies,it has the distinguished advantages that present clinical imaging technologies without.EIT has the characteristics of noninvasive,harmless,without the use of the nuclide and continuity monitoring,especially the functional imaging,which has important significance for the diagnosis and prevention of disease.The current existing EIT hardware system needs double power supply,whose system circuit complex,the analog devices in which are various.In order to simplify the EIT system hardware circuit,reduce the volume of measurement equipment and improve the mobility of the hardware system,a complete set of EIT hardware system was established,and the EIT hardware system which has been established was measured by means of experiments.In this paper,a set of EIT hardware system was established based on microcontrollers and FPGA which act as main control circuit.First,a feasible and easy to implement EIT hardware system design was confirmed,which mainly includes the choice of the master control device,design and realization of the sine signal source?multi-channel analog switch and electrode system selection and design?the implementation of incentive mode and implementation of the measured signal demodulation technology.According to the existing frequency synthesis technology,signal generator based on direct digital frequency synthesis technology was designed and realized,whose frequency and amplitude can be adjusted.Currently common voltage controlled current sources used in EIT hardware system were analyzed briefly,and the current source circuit was optimized according to the characteristics of the current source;the orthogonal sequence demodulation was selected as the method of phase sensitive demodulation;16 electrodes made of salt water tank as the experimental measurement and adjacent incentive mode was select.experiments are made on different parts of EIT hardware system.Sine waveform signal generator test results were got,the parameters of optimized current source circuit were measured and calculated,the curve of the channel consistency was got by do the experiments on salt water tank.The experimental results show that,the relatively stable signal can be out by sine signal generator,current source has a good performance,certain channel consistency is realized.Stimulation and measurement can be carried out by the EIT hardware system in this paper,and relatively stable results of measurements can be acquired.The method of realization in this paper provides a reference for the design of portable EIT hardware system.