{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,15]],"date-time":"2025-11-15T17:06:07Z","timestamp":1763226367706,"version":"build-2065373602"},"reference-count":35,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2016,7,25]],"date-time":"2016-07-25T00:00:00Z","timestamp":1469404800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Portuguese Foundation for Science and Technology (FCT), Portugal","award":["SFRH\/BD\/76441\/2011"],"award-info":[{"award-number":["SFRH\/BD\/76441\/2011"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>A new prototype of a multi-frequency electrical impedance tomography system is presented. The system uses a field-programmable gate array as a main controller and is configured to measure at different frequencies simultaneously through a composite waveform. Both real and imaginary components of the data are computed for each frequency and sent to the personal computer over an ethernet connection, where both time-difference imaging and frequency-difference imaging are reconstructed and visualized. The system has been tested for both time-difference and frequency-difference imaging for diverse sets of frequency pairs in a resistive\/capacitive test unit and in self-experiments. To our knowledge, this is the first work that shows preliminary frequency-difference images of in-vivo experiments. Results of time-difference imaging were compared with simulation results and shown that the new prototype performs well at all frequencies in the tested range of 60 kHz\u2013960 kHz. For frequency-difference images, further development of algorithms and an improved normalization process is required to correctly reconstruct and interpreted the resulting images.<\/jats:p>","DOI":"10.3390\/s16081158","type":"journal-article","created":{"date-parts":[[2016,7,25]],"date-time":"2016-07-25T10:04:26Z","timestamp":1469441066000},"page":"1158","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":31,"title":["System Description and First Application of an FPGA-Based Simultaneous Multi-Frequency Electrical Impedance Tomography"],"prefix":"10.3390","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-5812-4394","authenticated-orcid":false,"given":"Susana","family":"Aguiar Santos","sequence":"first","affiliation":[{"name":"Philips Chair for Medical Information Technology, RWTH Aachen University, Pauwelsstrasse 20, Aachen 52074, Germany"}]},{"given":"Anne","family":"Robens","sequence":"additional","affiliation":[{"name":"Philips Chair for Medical Information Technology, RWTH Aachen University, Pauwelsstrasse 20, Aachen 52074, Germany"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9641-4221","authenticated-orcid":false,"given":"Anna","family":"Boehm","sequence":"additional","affiliation":[{"name":"Philips Chair for Medical Information Technology, RWTH Aachen University, Pauwelsstrasse 20, Aachen 52074, Germany"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6898-6887","authenticated-orcid":false,"given":"Steffen","family":"Leonhardt","sequence":"additional","affiliation":[{"name":"Philips Chair for Medical Information Technology, RWTH Aachen University, Pauwelsstrasse 20, Aachen 52074, Germany"}]},{"given":"Daniel","family":"Teichmann","sequence":"additional","affiliation":[{"name":"Philips Chair for Medical Information Technology, RWTH Aachen University, Pauwelsstrasse 20, Aachen 52074, Germany"}]}],"member":"1968","published-online":{"date-parts":[[2016,7,25]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1917","DOI":"10.1007\/s00134-012-2684-z","article-title":"Electrical impedance tomography: The holy grail of ventilation and perfusion monitoring?","volume":"38","author":"Leonhardt","year":"2012","journal-title":"Intensive Care Med."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"63","DOI":"10.1146\/annurev.bioeng.8.061505.095716","article-title":"Bioimpedance Tomography (Electrical Impedance Tomography)","volume":"8","author":"Bayford","year":"2006","journal-title":"Annu. 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