A stable electrical impedance tomography system for continuous monitoring of pulmonary respiration

Pulmonary monitoring can be performed using electrical impedance tomography systems, owing to their fast operation, non-invasiveness, and low associated cost. However, continuous and stable lung imaging has some flaws owing to the instability of the electrodes, heartbeat, blood flow, and other factors. A complete pulmonary monitoring system including an electrode system, a hardware system, and imaging software was implemented in this study, and it demonstrated significant improvement in four aspects. (i) a system of electrodes with two elastic bands was designed to ensure force uniformity on all electrodes. (ii) a novel mechanism for real-time updating of reference data was proposed for eliminating the noise owing to miniscule motion of the electrodes. (iii) a method for detecting and dealing with poor contact electrodes was suggested for ensuring stable imaging. (iv) Principal component analysis (PCA) method is used to eliminate the noise owing to heartbeat and blood flow. Finally, respiration was continuously monitored for more than four hours, and the reconstructed images, pulmonary ventilation volume, tidal volume, and respiratory cycles were stable and reliable, indicating that the designed system can achieve continuous stable monitoring of pulmonary respiration.