{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,14]],"date-time":"2026-10-14T20:18:07Z","timestamp":1792009087003,"version":"4.4.0"},"reference-count":26,"publisher":"MDPI AG","issue":"14","license":[{"start":{"date-parts":[[2024,7,16]],"date-time":"2024-07-16T00:00:00Z","timestamp":1721088000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Kate Gleason College of Engineering"},{"name":"College of Engineering Technology"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Non-invasive monitoring of pulmonary health may be useful for tracking several conditions such as COVID-19 recovery and the progression of pulmonary edema. Some proposed methods use impedance-based technologies to non-invasively measure the thorax impedance as a function of respiration but face challenges that limit the feasibility, accuracy, and practicality of tracking daily changes. In our prior work, we demonstrated a novel approach to monitor respiration by measuring changes in impedance from the back of the thigh. We reported the concept of using thigh\u2013thigh bioimpedance measurements for measuring the respiration rate and demonstrated a linear relationship between the thigh\u2013thigh bioimpedance and lung tidal volume. Here, we investigate the variability in thigh\u2013thigh impedance measurements to further understand the feasibility of the technique for detecting a change in the respiratory status due to disease onset or recovery if used for long-term in-home monitoring. Multiple within-session and day-to-day impedance measurements were collected at 80 kHz using dry electrodes (thigh) and wet electrodes (thorax) across the five healthy subjects, along with simultaneous gold standard spirometer measurements for three consecutive days. The peak\u2013peak bioimpedance measurements were found to be highly correlated (0.94 \u00b1 0.03 for dry electrodes across thigh; 0.92 \u00b1 0.07 for wet electrodes across thorax) with the peak\u2013peak spirometer tidal volume. The data across five subjects indicate that the day-to-day variability in the relationship between impedance and volume for thigh\u2013thigh measurements is smaller (average of 14%) than for the thorax (40%). However, it is affected by food and water and might limit the accuracy of the respiratory tidal volume.<\/jats:p>","DOI":"10.3390\/s24144612","type":"journal-article","created":{"date-parts":[[2024,7,17]],"date-time":"2024-07-17T15:15:19Z","timestamp":1721229319000},"page":"4612","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":8,"title":["Day-to-Day Variability in Measurements of Respiration Using Bioimpedance from a Non-Standard Location"],"prefix":"10.3390","volume":"24","author":[{"given":"Krittika","family":"Goyal","sequence":"first","affiliation":[{"name":"Department of Manufacturing and Mechanical Engineering Technology, Rochester Institute of Technology, Rochester, NY 14623, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dishant","family":"Shah","sequence":"additional","affiliation":[{"name":"Department of Manufacturing and Mechanical Engineering Technology, Rochester Institute of Technology, Rochester, NY 14623, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7211-6745","authenticated-orcid":false,"given":"Steven W.","family":"Day","sequence":"additional","affiliation":[{"name":"Department of Biomedical Engineering, Rochester Institute of Technology, Rochester, NY 14623, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2024,7,16]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"M\u00e4lberg, J., Hadziosmanovic, N., and Smekal, D. 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