{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T03:16:46Z","timestamp":1760239006481,"version":"build-2065373602"},"reference-count":48,"publisher":"MDPI AG","issue":"19","license":[{"start":{"date-parts":[[2020,9,24]],"date-time":"2020-09-24T00:00:00Z","timestamp":1600905600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100010198","name":"Ministerio de Econom\u00eda, Industria y Competitividad, Gobierno de Espa\u00f1a","doi-asserted-by":"publisher","award":["CTQ2017-88079-P","CTQ2014-53442-P","BES-2009-026919","PTQ-15-07922","PTQ-15-07912"],"award-info":[{"award-number":["CTQ2017-88079-P","CTQ2014-53442-P","BES-2009-026919","PTQ-15-07922","PTQ-15-07912"]}],"id":[{"id":"10.13039\/501100010198","id-type":"DOI","asserted-by":"publisher"}]},{"name":"CEI BioTic Granada Campus","award":["Project CEIbioTIC14-2015"],"award-info":[{"award-number":["Project CEIbioTIC14-2015"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Phase-resolved luminescence chemical sensors provide the analyte determination based on the estimation of the luminescence lifetime. The lifetime is estimated from an analysis of the amplitudes and\/or phases of the excitation and emission signals at one or several modulation frequencies. This requires recording both the excitation signal (used to modulate the light source) and the emission signal (obtained from an optical transducer illuminated by the luminescent sensing phase). The excitation signal is conventionally used as reference, in order to obtain the modulation factor (the ratio between the emission and the excitation amplitudes) and\/or the phase shift (the difference between the emission and the excitation phases) at each modulation frequency, which are used to estimate the luminescence lifetime. In this manuscript, we propose a new method providing the luminescence lifetimes (based either on amplitudes or phases) using only the emission signal (i.e., omitting the excitation signal in the procedure). We demonstrate that the luminescence lifetime can be derived from the emission signal when it contains at least two harmonics, because in this case the amplitude and phase of one of the harmonics can be used as reference. We present the theoretical formulation as well as an example of application to an oxygen measuring system. The proposed self-referenced lifetime estimation provides two practical advantages for luminescence chemical sensors. On one hand, it simplifies the instrument architecture, since only one analog-to-digital converter (for the emission signal) is necessary. On the other hand, the self-referenced estimation of the lifetime improves the robustness against degradation of the sensing phase or variations in the optical coupling, which reduces the recalibration requirements when the lifetimes are based on amplitudes.<\/jats:p>","DOI":"10.3390\/s20195482","type":"journal-article","created":{"date-parts":[[2020,9,25]],"date-time":"2020-09-25T01:39:33Z","timestamp":1600997973000},"page":"5482","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Self-Referenced Multifrequency Phase-Resolved Luminescence Spectroscopy"],"prefix":"10.3390","volume":"20","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9736-5190","authenticated-orcid":false,"given":"Angel","family":"de la Torre","sequence":"first","affiliation":[{"name":"Department of Signal Theory, Networking and Communications, University of Granada, 18071 Granada, Spain"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4863-9095","authenticated-orcid":false,"given":"Santiago","family":"Medina-Rodr\u00edguez","sequence":"additional","affiliation":[{"name":"By Techdesign S.L., 28500 Arganda del Rey, Madrid, Spain"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3746-0978","authenticated-orcid":false,"given":"Jose C.","family":"Segura","sequence":"additional","affiliation":[{"name":"Department of Signal Theory, Networking and Communications, University of Granada, 18071 Granada, Spain"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6181-2833","authenticated-orcid":false,"given":"Jorge F.","family":"Fern\u00e1ndez-S\u00e1nchez","sequence":"additional","affiliation":[{"name":"Department of Analytical Chemistry, University of Granada, 18071 Granada, Spain"}]}],"member":"1968","published-online":{"date-parts":[[2020,9,24]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"219","DOI":"10.1016\/0925-4005(95)01686-4","article-title":"Recent progress in optical oxygen sensor instrumentation","volume":"29","author":"Trettnak","year":"1995","journal-title":"Sens. Actuators B Chem."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Geddes, C.D., and Lakowicz, J.R. (2002). Lifetime-Based Sensing. Topics in Fluorescence Spectroscopy, Springer.","DOI":"10.1007\/b112905"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"344","DOI":"10.1007\/s00216-004-2581-6","article-title":"Luminescent optical sensors","volume":"379","author":"Orellana","year":"2004","journal-title":"Anal. Bioanal. Chem."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Wolfbeis, O.S., Weidgans, B.M., Baldini, F., Chester, A.N., Homola, J., and Martellucci, S. (2006). Fiber Optic Chemical Sensors and Biosensors: A View Back Optical Chemical Sensors, Springer.","DOI":"10.1007\/1-4020-4611-1_2"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1110","DOI":"10.1016\/j.snb.2012.09.051","article-title":"An open and low-cost optical-fiber measurement system for the optical detection of oxygen using a multifrequency phase-resolved method","volume":"176","year":"2013","journal-title":"Sens. Actuators B Chem."},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Papkovsky, D.B., and Dmitriev, R.I. (2018). CHAPTER 6: Progress in Phosphorescence Lifetime Measurement Instrumentation for Oxygen Sensing. Quenched-Phosphorescence Detection of Molecular Oxygen: Applications in Life Sciences, The Royal Society of Chemistry.","DOI":"10.1039\/9781788013451"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1159","DOI":"10.4319\/lo.1995.40.6.1159","article-title":"Fiber-optic oxygen microsensors, a new tool in aquatic biology","volume":"40","author":"Klimant","year":"1995","journal-title":"Limnol. Oceanogr."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"226","DOI":"10.1016\/0925-4005(95)01687-2","article-title":"Development of a LED-based phase fluorimetric oxygen sensor using evanescent wave excitation of a sol-gel immobilized dye","volume":"29","author":"MacCraith","year":"1995","journal-title":"Sens. Actuators B"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"231","DOI":"10.1016\/0925-4005(95)01688-0","article-title":"FLOX\u2014An oxygen-flux-measuring system using a phase-modulation method to evaluate the oxygen-dependent fluorescence lifetime","volume":"29","author":"Holst","year":"1995","journal-title":"Sens. Actuators B"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"3162","DOI":"10.1021\/j100010a029","article-title":"Effects of polymer matrixes on the time-resolved luminescence of a ruthenium complex quenched by oxygen","volume":"99","author":"Draxler","year":"1995","journal-title":"J. Phys. Chem."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"506","DOI":"10.1016\/S0925-4005(97)80120-7","article-title":"Miniaturized luminescence lifetime-based oxygen sensor instrumentation utilizing a phase modulation technique","volume":"36","author":"Trettnak","year":"1996","journal-title":"Sens. Actuators B"},{"key":"ref_12","unstructured":"Dakin, J., and Culshaw, B. (1997). Optical Fiber Sensors: Applications, Analysis and Future Trends, Artech House."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/S1010-6030(98)00418-3","article-title":"Luminescence quenching of Ru(II) complexes in polydimethylsiloxane sensors for oxygen","volume":"120","author":"Bossi","year":"1999","journal-title":"J. Photochem. Photobiol. A Chem."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1439","DOI":"10.1016\/S0956-5663(03)00072-1","article-title":"Development of catheter-type optical oxygen sensor and applications to bioinstrumentation","volume":"18","author":"Tsukada","year":"2003","journal-title":"Biosens. Bioelectron."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"701","DOI":"10.1016\/j.snb.2006.01.051","article-title":"Highly sensitive optical fiber oxygen sensor using Pt(II) complex embedded in sol-gel matrices","volume":"119","author":"Yeh","year":"2006","journal-title":"Sens. Actuators B"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"29","DOI":"10.1109\/JSEN.2007.912552","article-title":"A magnetically controlled wireless optical oxygen sensor for intraocular measurements","volume":"8","author":"Ergeneman","year":"2008","journal-title":"IEEE Sens. J."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"608","DOI":"10.1016\/j.snb.2005.07.009","article-title":"Application of frequency spectroscopy to fluorescence-based oxygen sensors","volume":"113","author":"Ogurtsov","year":"2006","journal-title":"Sens. Actuators B"},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Lakowicz, J.R. (2006). Principles of Fluorescence Spectroscopy, Springer. [3rd ed.].","DOI":"10.1007\/978-0-387-46312-4"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"5245","DOI":"10.1021\/ac4030895","article-title":"Improved Multifrequency Phase-Modulation Method That Uses Rectangular-Wave Signals to Increase Accuracy in Luminescence Spectroscopy","volume":"86","author":"Arregui","year":"2014","journal-title":"Anal. Chem."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"334","DOI":"10.1016\/j.snb.2013.10.131","article-title":"Evaluation of a simple PC-based quadrature detection method at very low SNR for luminescence spectroscopy","volume":"192","year":"2014","journal-title":"Sens. Actuators B Chem."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"521","DOI":"10.1016\/j.snb.2015.10.059","article-title":"Direct estimation of the standard error in phase-resolved luminescence measurements: Application to an oxygen measuring system","volume":"224","year":"2016","journal-title":"Sens. Actuators B Chem."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1490","DOI":"10.1366\/0003702991946109","article-title":"Measurement of the intensity of long-lifetime luminophores in the presence of background signals using phase-modulation fluorometry","volume":"53","author":"Szmacinski","year":"1999","journal-title":"Appl. Spectrosc."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"160","DOI":"10.1016\/S0925-4005(02)00019-9","article-title":"Method for lifetime-based chemical sensing using the demodulation of the luminescence signal","volume":"84","author":"Andrzejewski","year":"2002","journal-title":"Sens. Actuators B"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"4607","DOI":"10.1039\/c3an00239j","article-title":"High performance optical sensing nanocomposites for low and ultra-low oxygen concentrations using phase-shift measurements","volume":"138","author":"Baranoff","year":"2013","journal-title":"Analyst"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"11401","DOI":"10.1039\/C5CC04326C","article-title":"Copper(I) complexes as alternatives to iridium(III) complexes for highly efficient oxygen sensing","volume":"51","author":"Poole","year":"2015","journal-title":"Chem. Commun."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"221","DOI":"10.1016\/j.snb.2016.07.046","article-title":"Real-time optimal combination of multifrequency information in phase-resolved luminescence spectroscopy based on rectangular-wave signals","volume":"238","year":"2017","journal-title":"Sens. Actuators B Chem."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"62","DOI":"10.1016\/j.aca.2012.03.050","article-title":"Dual lifetime referenced fluorometry for the determination of doxorubicin in urine","volume":"729","author":"Wolfbeis","year":"2012","journal-title":"Anal. Chim. Acta"},{"key":"ref_28","first-page":"1","article-title":"Self-referenced luminescence thermometry with Sm3+ doped TiO2 nanoparticles","volume":"25","author":"Ahrenkiel","year":"2014","journal-title":"Nanotechnology"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"4238","DOI":"10.1021\/acs.inorgchem.7b00252","article-title":"Mixed-lanthanide porous coordination polymers showing range-tunable ratiometric luminescence for O2 sensing","volume":"56","author":"Ye","year":"2017","journal-title":"Inorg. Chem."},{"key":"ref_30","first-page":"1","article-title":"Highly sensitive dual self-referencing temperature readout from the Mn4+\/Ho3+ binary luminescence thermometry probe","volume":"6","year":"2018","journal-title":"Adv. Opt. Mater."},{"key":"ref_31","unstructured":"Papkovsky, D.B., and Dmitriev, R.I. (2018). CHAPTER 8: Monitoring of Extracellular and Intracellular O2 on a Time-resolved Fluorescence Plate Reader. Quenched-Phosphorescence Detection of Molecular Oxygen: Applications in Life Sciences, The Royal Society of Chemistry."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"153","DOI":"10.1016\/j.jlumin.2018.01.029","article-title":"Spectroscopic characterization and temperature-dependent upconversion behavior of Er3+ and Yb3+ co-doped zinc phosphate glass","volume":"197","author":"Tang","year":"2018","journal-title":"J. Lumin."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"8999","DOI":"10.1039\/C8TC02726A","article-title":"New red-emitting Schiff base chelates: Promising dyes for sensing and imaging of temperature and oxygen via phosphorescence decay time","volume":"6","author":"Borisov","year":"2018","journal-title":"J. Mater. Chem. C"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"7756","DOI":"10.1021\/acs.analchem.9b01174","article-title":"Simple self-referenced luminescent pH sensors based on upconversion nanocrystals and pH-sensitive fluorescent BODIPY dyes","volume":"91","author":"Radunz","year":"2019","journal-title":"Anal. Chem."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"267","DOI":"10.3389\/fchem.2019.00267","article-title":"Self-calibrated double luminescent thermometers through upconverting nanoparticles","volume":"7","author":"Brites","year":"2019","journal-title":"Front. Chem."},{"key":"ref_36","unstructured":"Wolfbeis, O.S. (1991). Fiber-Optic Chemical Sensors and Biosensors, CRC Press."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"3532","DOI":"10.1002\/anie.201105459","article-title":"The Art of Fluorescence Imaging with Chemical Sensors","volume":"51","year":"2012","journal-title":"Angew. Chem. Int. Ed. Engl."},{"key":"ref_38","unstructured":"Proakis, J.G., and Manolakis, D.G. (2007). Digital Signal Processing-Principles, Algorithms and Applications, Pearson Prentice Hall. [4th ed.]."},{"key":"ref_39","doi-asserted-by":"crossref","unstructured":"Sundararajan, D. (2001). The Discrete Fourier Transform: Theory, Algorithms and Applications, World Scientific Publishing Co. Pte. Ltd.","DOI":"10.1142\/9789812810298"},{"key":"ref_40","first-page":"291","article-title":"Optochemical Sensors Based on Luminescence","volume":"Volume 7","author":"Grimes","year":"2006","journal-title":"Encyclopedia of Sensors"},{"key":"ref_41","doi-asserted-by":"crossref","unstructured":"de la Torre, A., Medina-Rodriguez, S., Segura, J.C., and Fernandez-Sanchez, J.F. (2020). A polynomial-exponent model for calibrating the frequency response of photoluminescence-based sensors. Sensors, 20.","DOI":"10.3390\/s20164635"},{"key":"ref_42","first-page":"1","article-title":"Oxygen Sensing","volume":"Volume 381","author":"Sen","year":"2004","journal-title":"Methods in Enzymology"},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"1377","DOI":"10.1021\/ac00104a012","article-title":"Modeling of Luminescence Quenching-Based Sensors: Comparison of Multisite and Nonlinear Gas Solubility Models","volume":"67","author":"Demas","year":"1995","journal-title":"Anal. Chem."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"17","DOI":"10.1016\/S0925-4005(01)00921-2","article-title":"Approximation of calibration of phase-fluorimetric oxygen sensors on the basis of physical models","volume":"81","author":"Ogurtsov","year":"2001","journal-title":"Sens. Actuators B Chem."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"89","DOI":"10.1016\/S0925-4005(02)00312-X","article-title":"Modeling of luminescence-based oxygen sensors with non-uniform distribution of excitation and quenching characteristics inside active medium","volume":"88","author":"Ogurtsov","year":"2003","journal-title":"Sens. Actuators B Chem."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"917","DOI":"10.1016\/j.snb.2005.03.079","article-title":"Modelling of phase-fluorometric oxygen sensors: Consideration of temperature effects and operational requirements","volume":"113","author":"Ogurtsov","year":"2006","journal-title":"Sens. Actuators B Chem."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"35","DOI":"10.1016\/0925-4005(93)85236-4","article-title":"Luminescence-based sensors: Microheterogeneous and temperature effects","volume":"11","author":"Demas","year":"1993","journal-title":"Sens. Actuators B Chem."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"278","DOI":"10.1016\/j.snb.2015.02.022","article-title":"On the calibration of chemical sensors based on photoluminescence: Selecting the appropriate optimization criterion","volume":"212","year":"2015","journal-title":"Sens. Actuators B Chem."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/20\/19\/5482\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T10:13:23Z","timestamp":1760177603000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/20\/19\/5482"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2020,9,24]]},"references-count":48,"journal-issue":{"issue":"19","published-online":{"date-parts":[[2020,10]]}},"alternative-id":["s20195482"],"URL":"https:\/\/doi.org\/10.3390\/s20195482","relation":{},"ISSN":["1424-8220"],"issn-type":[{"type":"electronic","value":"1424-8220"}],"subject":[],"published":{"date-parts":[[2020,9,24]]}}}