Design of a serial data collection system for electrical impedance tomography

Abstract

This thesis is concerned with the design and implementationof electronic hardware of a serial data collection system fore I ec t rica 1 impedance tomography. The ac tu a 1 des Ign uses thecurrent injection-voltage measurement technique with 16electrodes. The electrodes are addressed through 4multiplexers. A current drive of 2 mA(rms) at 45 kHz ismultiplexed to adjacent pairs of electrodes and peripheralpotential differences are recorded by serially steppingaround adjacent electrode pairs. 208 voltage measurements aremade for one complete set of proj ect ions. The measuredvalues are transmitted to the computer where they aredigitized and stored in the memory in array form.To comply with electrical safety requirements, both currentinjection and voltage measurement circuits are isolated fromeach other as well as from earth ground.