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Transcript
Michelle Mellenthin Hardware Improvements to Reduce Interference and Improve Electrode-Skin Modeling in Electrical Impedance Tomography Electrical Impedance Tomography (EIT) is a low-cost, portable, and radiation-free functional imaging modality that can be used to create low spatial resolution images which reflect differences in ion concentration or electrical properties of biological tissues. One of the main research interests of the EIT laboratories at both Colorado State University (CSU) and the University of Sao Paulo (USP) is creating cross-sectional images of the human chest to allow for better diagnosis of different lung pathologies. The quality of EIT images depends greatly upon both the reconstruction algorithm and hardware. Improved image quality, or better spatial resolution and accuracy of reconstructed values in EIT images, is essential for better distinguishability between tissues and anomalies. To aid in upcoming experiments involving electrode-skin modeling and reconstruction algorithms, the hardware system needed to be modified to accurately acquire complex voltages. The important changes implemented were: (1) an active electrode to allow for accurate acquisition of complex voltages, (2) a novel bipolar current source, and (3) analog Butterworth anti-aliasing filters to further reduce noise. One of the difficulties encountered during this work was that the detailed design of the data acquisition system and the large number of improvements needed was not fully divulged until arrival. In addition, the project timeline had to be altered because all expensive hardware purchases needed to be made through the accountants of the university. The data acquisition boards that were supposed to arrive before the start of the fellowship did not arrive until the end. Despite challenges, the outcomes of this work are of considerable importance to both laboratories. Most significantly, this work resulted in an upgraded EIT system, which is less sensitive to interference. We also investigated novel designs for current sources, which could be adopted by other groups. The use of the new tomographer will allow for better versatility during testing, and the complex voltage measurements it acquires are crucial for my doctoral project involving skin modeling.