一体化多电极电阻抗断层成像数据采集系统设计

An Integrated Design of Multi-Electrode Data Acquisition System of Electrical Impedance Tomography

非均匀与均匀介质电场的空间分布在边界条件上的关系是影响旋转电极EIT成像分辨率的因素之一。为此设计了一种8层共1 024电极的电阻抗断层成像数据采集系统。该系统采用一体化设计方案,8层PCB层叠结构,用排针、排母进行物理支撑和电气连接,最大限度地减少了引线对信号采集的影响。PCB工艺形成的电极具有数量多,分布均匀,在不同旋转方向上形成的电场一致性较好的特点。系统采用在FPGA中构建NIOS II软核处理器进行整体控制。结果表明,系统物理模型所形成的介质电场均匀,从不同旋转角度上实测的电场分布的其一致性较好;电场分布和数据采集的结果达到设计要求。

The relation between space distribution of heterogeneous medium electric field and homogeneous medium electric field on boundary conditions is one of factors affecting rotating electrode imaging of electrical impedance tomography（EIT）.Therefore,an EIT data acquisition system,having 1 024 electrodes in 8 PCB layers,was designed.The physical supporting and electrical connection of 8 PCB layers were implemented with pin headers and sockets,effectively reducing the interfering signals resulted from lead wires.The electrode array,made by PCB technology,had the advantages of homogeneous space distribution and good consistence of electric field in different direction of rotation.In addition,a soft-core processor NIOS II embedded in FPGA was used as a controller of the system.Experimental results showed that the distribution of medium electric field of physical model was homogeneous with good consistence tested at different rotation angles.