{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T02:49:51Z","timestamp":1760150991897,"version":"build-2065373602"},"reference-count":72,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2022,2,10]],"date-time":"2022-02-10T00:00:00Z","timestamp":1644451200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100000002","name":"National Institutes of Health","doi-asserted-by":"publisher","award":["R03 EB027336"],"award-info":[{"award-number":["R03 EB027336"]}],"id":[{"id":"10.13039\/100000002","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Energy Expenditure (EE) (kcal\/day), a key element to guide obesity treatment, is measured from CO2 production, VCO2 (mL\/min), and\/or O2 consumption, VO2 (mL\/min). Current technologies are limited due to the requirement of wearable facial accessories. A novel system, the Smart Pad, which measures EE via VCO2 from a room\u2019s ambient CO2 concentration transients was evaluated. Resting EE (REE) and exercise VCO2 measurements were recorded using Smart Pad and a reference instrument to study measurement duration\u2019s influence on accuracy. The Smart Pad displayed 90% accuracy (\u00b11 SD) for 14\u201319 min of REE measurement and for 4.8\u20137.0 min of exercise, using known room\u2019s air exchange rate. Additionally, the Smart Pad was validated measuring subjects with a wide range of body mass indexes (BMI = 18.8 to 31.4 kg\/m2), successfully validating the system accuracy across REE\u2019s measures of ~1200 to ~3000 kcal\/day. Furthermore, high correlation between subjects\u2019 VCO2 and \u03bb for CO2 accumulation was observed (p &lt; 0.00001, R = 0.785) in a 14.0 m3 sized room. This finding led to development of a new model for REE measurement from ambient CO2 without \u03bb calibration using a reference instrument. The model correlated in nearly 100% agreement with reference instrument measures (y = 1.06x, R = 0.937) using an independent dataset (N = 56).<\/jats:p>","DOI":"10.3390\/s22041355","type":"journal-article","created":{"date-parts":[[2022,2,11]],"date-time":"2022-02-11T02:40:17Z","timestamp":1644547217000},"page":"1355","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["A Smart System for the Contactless Measurement of Energy Expenditure"],"prefix":"10.3390","volume":"22","author":[{"given":"Mark","family":"Sprowls","sequence":"first","affiliation":[{"name":"School of Engineering for Matter, Transport and Energy, Arizona State University, Tempe, AZ 85281, USA"},{"name":"Center for Bioelectronics and Biosensors, Biodesign Institute, Arizona State University, Tempe, AZ 85281, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1922-6280","authenticated-orcid":false,"given":"Shaun","family":"Victor","sequence":"additional","affiliation":[{"name":"School of Engineering for Matter, Transport and Energy, Arizona State University, Tempe, AZ 85281, USA"},{"name":"Center for Bioelectronics and Biosensors, Biodesign Institute, Arizona State University, Tempe, AZ 85281, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sabrina Jimena","family":"Mora","sequence":"additional","affiliation":[{"name":"Center for Bioelectronics and Biosensors, Biodesign Institute, Arizona State University, Tempe, AZ 85281, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Oscar","family":"Osorio","sequence":"additional","affiliation":[{"name":"Center for Bioelectronics and Biosensors, Biodesign Institute, Arizona State University, Tempe, AZ 85281, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Gabriel","family":"Pyznar","sequence":"additional","affiliation":[{"name":"Center for Bioelectronics and Biosensors, Biodesign Institute, Arizona State University, Tempe, AZ 85281, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hugo","family":"Destaillats","sequence":"additional","affiliation":[{"name":"Indoor Environment Group, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Courtney","family":"Wheatley-Guy","sequence":"additional","affiliation":[{"name":"Mayo Clinic, Scottsdale, AZ 85289, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Bruce","family":"Johnson","sequence":"additional","affiliation":[{"name":"Mayo Clinic, Scottsdale, AZ 85289, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Doina","family":"Kulick","sequence":"additional","affiliation":[{"name":"Mayo Clinic, Scottsdale, AZ 85289, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Erica","family":"Forzani","sequence":"additional","affiliation":[{"name":"School of Engineering for Matter, Transport and Energy, Arizona State University, Tempe, AZ 85281, USA"},{"name":"Center for Bioelectronics and Biosensors, Biodesign Institute, Arizona State University, Tempe, AZ 85281, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2022,2,10]]},"reference":[{"key":"ref_1","unstructured":"Hales, C.M., Carroll, M.D., Fryar, C.D., and Ogden, C.L. (2017). Prevalence of Obesity among Adults and Youth: United States, 2015\u20132016, National Center for Health Statistics."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"2211","DOI":"10.1056\/NEJMoa1000367","article-title":"Body-Mass Index and Mortality among 1.46 Million White Adults","volume":"363","author":"Hartge","year":"2010","journal-title":"N. Engl. J. Med."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"187","DOI":"10.1001\/jama.289.2.187","article-title":"Years of Life Lost Due to Obesity","volume":"289","author":"Fontaine","year":"2003","journal-title":"JAMA J. Am. Med. Assoc."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Prospective Studies Collaboration (2009). Body-mass index and cause-specific mortality in 900 000 adults: Collaborative analyses of 57 prospective studies. Lancet, 373, 1083\u20131096.","DOI":"10.1016\/S0140-6736(09)60318-4"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1299","DOI":"10.1210\/jc.2012-3115","article-title":"Update on treatment strategies for obesity","volume":"98","author":"Wyatt","year":"2013","journal-title":"J. Clin. Endocrinol. Metab."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"801","DOI":"10.1152\/physrev.1955.35.4.801","article-title":"Human Energy Expenditure","volume":"35","author":"Passmore","year":"1955","journal-title":"Physiol. Rev."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1123","DOI":"10.1079\/PHN2005800","article-title":"Measurement of energy expenditure","volume":"8","author":"Levine","year":"2005","journal-title":"Public Health Nutr."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"287","DOI":"10.1016\/0026-0495(88)90110-2","article-title":"The theoretical bases of indirect calorimetry: A review","volume":"37","author":"Ferrannini","year":"1988","journal-title":"Metabolism"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"377","DOI":"10.1177\/0115426507022004377","article-title":"Indirect Calorimetry: A Practical Guide for Clinicians","volume":"22","author":"Haugen","year":"2007","journal-title":"Nutr. Clin. Pract."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1113\/jphysiol.1949.sp004363","article-title":"New methods for calculating metabolic rate with special reference to protein metabolism","volume":"109","author":"Weir","year":"1949","journal-title":"J. Physiol."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"976","DOI":"10.1016\/j.clnu.2013.03.022","article-title":"Bias and accuracy of resting metabolic rate equations in non-obese and obese adults","volume":"32","author":"Frankenfield","year":"2013","journal-title":"Clin. Nutr."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"241","DOI":"10.1093\/ajcn\/51.2.241","article-title":"A new predictive equation for resting energy expenditure in healthy individuals","volume":"51","author":"Mifflin","year":"1990","journal-title":"Am. J. Clin. Nutr."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"010","DOI":"10.17352\/2455-8583.000036","article-title":"Comparison of Resting Metabolic Rates: Calculated using predictive equation and measured using Portable Indirect Calorimeter","volume":"6","author":"Yue","year":"2019","journal-title":"Glob. J. Obes. Diabetes Metab. Syndr."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"367","DOI":"10.3389\/fendo.2018.00367","article-title":"Analysis of Predictive Equations for Estimating Resting Energy Expenditure in a Large Cohort of Morbidly Obese Patients","volume":"9","author":"Cancello","year":"2018","journal-title":"Front. Endocrinol."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"344","DOI":"10.1016\/j.jsams.2011.02.010","article-title":"Accuracy of four resting metabolic rate prediction equations: Effects of sex, body mass index, age, and race\/ethnicity","volume":"14","author":"Hasson","year":"2011","journal-title":"J. Sci. Med. Sport"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"922","DOI":"10.1002\/ncp.10374","article-title":"Accuracy of Resting Energy Expenditure Predictive Equations in Patients with Cancer","volume":"34","author":"Purcell","year":"2019","journal-title":"Nutr. Clin. Pract."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"613","DOI":"10.1016\/j.clnu.2013.09.009","article-title":"Accuracy of predictive equations for the measurement of resting energy expenditure in older subjects","volume":"33","author":"Siervo","year":"2014","journal-title":"Clin. Nutr."},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Chowdhury, E.A., Western, M.J., Nightingale, T.E., Peacock, O.J., and Thompson, D. (2017). Assessment of laboratory and daily energy expenditure estimates from consumer multi-sensor physical activity monitors. PLoS ONE, 12.","DOI":"10.1371\/journal.pone.0171720"},{"key":"ref_19","first-page":"E399","article-title":"Indirect calorimetry: Methodological and interpretative problems","volume":"258","author":"Simonson","year":"1990","journal-title":"Am. J. Physiol. Metab."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"386","DOI":"10.1038\/sj.ejcn.1600970","article-title":"Within- and between-subject variation in energy expenditure measured by the doubly-labelled water technique: Implications for validating reported dietary energy intake","volume":"54","author":"Black","year":"2000","journal-title":"Eur. J. Clin. Nutr."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"128","DOI":"10.1016\/j.jada.2008.10.004","article-title":"Assessing Validity and Reliability of Resting Metabolic Rate in Six Gas Analysis Systems","volume":"109","author":"Cooper","year":"2009","journal-title":"J. Am. Diet. Assoc."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"752","DOI":"10.1038\/oby.2003.105","article-title":"Comparison of Methods for Achieving 24-Hour Energy Balance in a Whole-Room Indirect Calorimeter","volume":"11","author":"Grunwald","year":"2003","journal-title":"Obes. Res."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1186\/s12986-015-0043-0","article-title":"Evaluation of a new whole room indirect calorimeter specific for measurement of resting metabolic rate","volume":"12","author":"Rising","year":"2015","journal-title":"Nutr. Metab."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"1613","DOI":"10.1002\/oby.22928","article-title":"Room Indirect Calorimetry Operating and Reporting Standards (RICORS 1.0): A Guide to Conducting and Reporting Human Whole-Room Calorimeter Studies","volume":"28","author":"Chen","year":"2020","journal-title":"Obesity"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"036012","DOI":"10.1088\/1752-7163\/aaaec9","article-title":"Assessing metabolic rate and indoor air quality with passive environmental sensors","volume":"12","author":"Ruiz","year":"2018","journal-title":"J. Breath Res."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"026004","DOI":"10.1088\/1752-7163\/abd52f","article-title":"A system for contact free energy expenditure assessment under free-living conditions: Monitoring metabolism for weight loss using carbon dioxide emission","volume":"15","author":"Sprowls","year":"2020","journal-title":"J. Breath Res."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"5628","DOI":"10.1109\/JIOT.2020.2980432","article-title":"A Flexible and Pervasive IoT-Based Healthcare Platform for Physiological and Environmental Parameters Monitoring","volume":"7","author":"Haghi","year":"2020","journal-title":"IEEE Internet Things J."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"217","DOI":"10.1039\/C7LC00914C","article-title":"Wearable sensors: Modalities, challenges, and prospects","volume":"18","author":"Heikenfeld","year":"2018","journal-title":"Lab Chip"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"1900109","DOI":"10.1002\/adhm.201900109","article-title":"Soft Wearable Pressure Sensors for Beat-to-Beat Blood Pressure Monitoring","volume":"8","author":"Kim","year":"2019","journal-title":"Adv. Healthc. Mater."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1109\/JTEHM.2018.2840678","article-title":"A Handheld, Colorimetric Optoelectronic Dynamics Analyzer for Measuring Total Ammonia of Biological Samples","volume":"6","author":"Liu","year":"2018","journal-title":"IEEE J. Transl. Eng. Health Med."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1038\/s41746-019-0128-7","article-title":"Contactless cardiac arrest detection using smart devices","volume":"2","author":"Chan","year":"2019","journal-title":"Npj Digit. Med."},{"key":"ref_32","doi-asserted-by":"crossref","unstructured":"Deng, Y., Sprowls, M., Mora, S.J., Kulick, D., Tao, N., Destaillats, H., and Forzani, E. (2020). An Unobstructive Sensing Method for Indoor Air Quality Optimization and Metabolic Assessment within Vehicles. Sensors, 20.","DOI":"10.3390\/s20247202"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"5138","DOI":"10.1364\/BOE.7.005138","article-title":"Accurate measurement of the pulse wave delay with imaging photoplethysmography","volume":"7","author":"Kamshilin","year":"2016","journal-title":"Biomed. Opt. Express"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"112656","DOI":"10.1016\/j.bios.2020.112656","article-title":"An integrated system of air sampling and simultaneous enrichment for rapid biosensing of airborne coronavirus and influenza virus","volume":"170","author":"Kim","year":"2020","journal-title":"Biosens. Bioelectron."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"252","DOI":"10.1038\/s41928-019-0258-6","article-title":"Vital-sign monitoring and spatial tracking of multiple people using a contactless radar-based sensor","volume":"2","author":"Mercuri","year":"2019","journal-title":"Nat. Electron."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"1091","DOI":"10.1109\/TBME.2015.2481896","article-title":"Noncontact Monitoring of Blood Oxygen Saturation Using Camera and Dual-Wavelength Imaging System","volume":"63","author":"Shao","year":"2016","journal-title":"IEEE Trans. Biomed. Eng."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"2760","DOI":"10.1109\/TBME.2014.2327024","article-title":"Noncontact Monitoring Breathing Pattern, Exhalation Flow Rate and Pulse Transit Time","volume":"61","author":"Shao","year":"2014","journal-title":"IEEE Trans. Biomed. Eng."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"1945","DOI":"10.1016\/j.buildenv.2007.11.015","article-title":"Air quality in hospital operating rooms","volume":"43","author":"Dascalaki","year":"2008","journal-title":"Build. Environ."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"348","DOI":"10.1016\/j.jenvman.2007.10.003","article-title":"Indoor air quality investigation according to age of the school buildings in Korea","volume":"90","author":"Yang","year":"2009","journal-title":"J. Environ. Manag."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"215","DOI":"10.1016\/j.buildenv.2011.08.018","article-title":"Ventilation rates in schools and pupils\u2019 performance","volume":"48","author":"Kochhar","year":"2012","journal-title":"Build. Environ."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"221","DOI":"10.1111\/j.1600-0668.1996.00002.x","article-title":"European Indoor Air Quality Audit Project in 56 Office Buildings","volume":"6","author":"Bluyssen","year":"1996","journal-title":"Indoor Air"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"1013","DOI":"10.1016\/S0140-6736(96)07220-0","article-title":"Sick-building syndrome","volume":"349","author":"Redlich","year":"1997","journal-title":"Lancet"},{"key":"ref_43","doi-asserted-by":"crossref","unstructured":"Batterman, S. (2017). Review and Extension of CO2-Based Methods to Determine Ventilation Rates with Application to School Classrooms. Int. J. Environ. Res. Public Health, 14.","DOI":"10.3390\/ijerph14020145"},{"key":"ref_44","first-page":"175","article-title":"Air Stuffiness and Air Exchange Rate in French Schools and Day-Care Centres","volume":"12","author":"Ramalho","year":"2013","journal-title":"Int. J. Vent."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"290","DOI":"10.1016\/j.energy.2014.10.028","article-title":"Indoor CO2 measurements in Serbian schools and ventilation rate calculation","volume":"77","author":"Turanjanin","year":"2014","journal-title":"Energy"},{"key":"ref_46","first-page":"39","article-title":"Simple and Cheap Air Change Rate Measurement Using CO2Concentration Decays","volume":"1","author":"Foradini","year":"2002","journal-title":"Int. J. Vent."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"162","DOI":"10.1016\/j.buildenv.2014.11.007","article-title":"CO2 tracer gas concentration decay method for measuring air change rate","volume":"84","author":"Cui","year":"2015","journal-title":"Build. Environ."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"139","DOI":"10.1021\/acs.est.0c03850","article-title":"Impact of Cognitive Tasks on CO2 and Isoprene Emissions from Humans","volume":"55","author":"Gall","year":"2021","journal-title":"Environ. Sci. Technol."},{"key":"ref_49","unstructured":"Tans, P., and Keeling, R. (2021, December 23). Trends in Atmospheric Carbon Dioxide: NOAA ESRL Global Monitoring Division, Available online: https:\/\/www.esrl.noaa.gov\/gmd\/ccgg\/trends\/gl_trend.html."},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"181","DOI":"10.1016\/S0360-1323(99)00064-5","article-title":"Development and application of an indoor air quality audit to an air-conditioned building in Singapore","volume":"36","author":"Cheong","year":"2001","journal-title":"Build. Environ."},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"691","DOI":"10.1038\/s41893-019-0323-1","article-title":"Direct human health risks of increased atmospheric carbon dioxide","volume":"2","author":"Jacobson","year":"2019","journal-title":"Nat. Sustain."},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"1671","DOI":"10.1289\/ehp.1104789","article-title":"Is CO2 an Indoor Pollutant? Direct Effects of Low-to-Moderate CO2 Concentrations on Human Decision-Making Performance","volume":"120","author":"Satish","year":"2012","journal-title":"Environ. Health Perspect."},{"key":"ref_53","unstructured":"FDA (2021, December 23). Medgraphics Ultima System 510(k) Premarket Notification: U.S. Food and Drug Administration, Available online: https:\/\/www.accessdata.fda.gov\/cdrh_docs\/pdf6\/K061731.pdf."},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"547","DOI":"10.1080\/07315724.2018.1552544","article-title":"The Thermic Effect of Food: A Review","volume":"38","author":"Calcagno","year":"2019","journal-title":"J. Am. Coll. Nutr."},{"key":"ref_55","doi-asserted-by":"crossref","first-page":"169","DOI":"10.1055\/s-2007-1024895","article-title":"Decrease in Respiratory Quotient During Exercise Following L-Carnitine Supplementation","volume":"10","author":"Gorostiaga","year":"1989","journal-title":"Int. J. Sports Med."},{"key":"ref_56","doi-asserted-by":"crossref","first-page":"606","DOI":"10.1152\/jappl.1961.16.4.606","article-title":"Respiratory quotient during exercise","volume":"16","author":"Issekutz","year":"1961","journal-title":"J. Appl. Physiol."},{"key":"ref_57","first-page":"121","article-title":"Association between substandard classroom ventilation rates and students\u2019 academic achievement","volume":"21","author":"Moschandreas","year":"2010","journal-title":"Indoor Air"},{"key":"ref_58","unstructured":"ASTM D 6245 (2022, February 07). Standard Guide for Using Indoor Carbon Dioxide Concentrations to Evaluate Indoor Air Quality and Ventilation: American Society for Testing and Materials (ASTM). Available online: https:\/\/www.astm.org\/."},{"key":"ref_59","doi-asserted-by":"crossref","unstructured":"Auerswald, S., H\u00f6rberg, C., Pflug, T., Pfafferott, J., Bongs, C., and Henning, H.-M. (2020). Experimental Investigation of the Air Exchange Effectiveness of Push-Pull Ventilation Devices. Energies, 13.","DOI":"10.3390\/en13215817"},{"key":"ref_60","doi-asserted-by":"crossref","first-page":"2159","DOI":"10.1249\/MSS.0000000000000346","article-title":"Estimating Energy Expenditure Using Heat Flux Measured at a Single Body Site","volume":"46","author":"Lyden","year":"2014","journal-title":"Med. Sci. Sports Exerc."},{"key":"ref_61","unstructured":"Novoselac, A., and Srebric, J. (2022, February 07). Comparison of Air Exchange Efficiency and Contaminant Removal Effectiveness as IAQ Indices ASHRAE Transactions. Available online: https:\/\/www.caee.utexas.edu\/prof\/novoselac\/Publications\/Novoselac_ASHRAE_Transactions_2003.pdf."},{"key":"ref_62","doi-asserted-by":"crossref","first-page":"903","DOI":"10.1136\/bmj.331.7521.903","article-title":"Standard deviations and standard errors","volume":"331","author":"Altman","year":"2005","journal-title":"BMJ"},{"key":"ref_63","unstructured":"FDA (2021, December 23). MasterScreen CPXTM 510(k) Premarket Notification (K072323). U.S. Food and Drug Administration, Available online: https:\/\/www.accessdata.fda.gov\/cdrh_docs\/pdf7\/K072323.pdf."},{"key":"ref_64","unstructured":"FDA (2021, December 23). OxyconTM Pro 510(k) Premarket Notification (K992214): U.S. Food and Drug Administration, Available online: https:\/\/www.accessdata.fda.gov\/cdrh_docs\/pdf\/K992214.pdf."},{"key":"ref_65","unstructured":"FDA (2021, December 23). VyntusTM\/SentrySuite Product Line 510(k) Premarket Notification (K133925): U.S. Food and Drug Administration, Available online: https:\/\/www.accessdata.fda.gov\/cdrh_docs\/pdf13\/K133925.pdf."},{"key":"ref_66","unstructured":"FDA (2021, December 23). OxyconTM Mobile 510(k) Premarket Notification (K023120): U.S. Food and Drug Administration, Available online: https:\/\/www.accessdata.fda.gov\/cdrh_docs\/pdf\/K023120.pdf."},{"key":"ref_67","unstructured":"FDA (2021, December 23). ReeVue Indirect Calorimeter, Model#8100 510(k) Premarket Notification. In Korr Medical Technologies Incorporated (Ed.): U.S. Food and Drug Administration, Available online: https:\/\/www.accessdata.fda.gov\/cdrh_docs\/pdf2\/K021490.pdf."},{"key":"ref_68","unstructured":"(2021, December 23). Cardiorespiratory Diagnostic System, Medical Graphics, Ultima Series. Available online: https:\/\/mgcdiagnostics.com\/images\/uploads\/documents\/Ultima_CPX_sellsheet_060155-001.pdf."},{"key":"ref_69","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1021\/cr60119a001","article-title":"The Antoine Equation for Vapor-pressure Data","volume":"38","author":"Thomson","year":"1946","journal-title":"Chem. Rev."},{"key":"ref_70","doi-asserted-by":"crossref","first-page":"S154","DOI":"10.1016\/S0002-8223(97)00754-2","article-title":"Indirect calorimetry: Technical aspects","volume":"97","author":"Matarese","year":"1997","journal-title":"J. Am. Diet Assoc."},{"key":"ref_71","doi-asserted-by":"crossref","first-page":"189","DOI":"10.1159\/000079556","article-title":"Fasting Respiratory Quotient as a Predictor of Long-Term Weight Changes in Non-Obese Women","volume":"48","author":"Marra","year":"2004","journal-title":"Ann. Nutr. Metab."},{"key":"ref_72","doi-asserted-by":"crossref","first-page":"21","DOI":"10.1177\/014860710302700121","article-title":"Clinical use of the respiratory quotient obtained from indirect calorimetry","volume":"27","author":"Lowen","year":"2003","journal-title":"J. Parenter. Enter. Nutr."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/22\/4\/1355\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T22:17:53Z","timestamp":1760134673000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/22\/4\/1355"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,2,10]]},"references-count":72,"journal-issue":{"issue":"4","published-online":{"date-parts":[[2022,2]]}},"alternative-id":["s22041355"],"URL":"https:\/\/doi.org\/10.3390\/s22041355","relation":{},"ISSN":["1424-8220"],"issn-type":[{"type":"electronic","value":"1424-8220"}],"subject":[],"published":{"date-parts":[[2022,2,10]]}}}