{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,22]],"date-time":"2026-01-22T12:51:35Z","timestamp":1769086295426,"version":"3.49.0"},"reference-count":29,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2017,6,2]],"date-time":"2017-06-02T00:00:00Z","timestamp":1496361600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>A technique for contactless electromagnetic interrogation of AT-cut quartz piezoelectric resonator sensors is proposed based on a primary coil electromagnetically air-coupled to a secondary coil connected to the electrodes of the resonator. The interrogation technique periodically switches between interleaved excitation and detection phases. During the excitation phase, the resonator is set into vibration by a driving voltage applied to the primary coil, whereas in the detection phase, the excitation signal is turned off and the transient decaying response of the resonator is sensed without contact by measuring the voltage induced back across the primary coil. This approach ensures that the readout frequency of the sensor signal is to a first order approximation independent of the interrogation distance between the primary and secondary coils. A detailed theoretical analysis of the interrogation principle based on a lumped-element equivalent circuit is presented. The analysis has been experimentally validated on a 4.432 MHz AT-cut quartz crystal resonator, demonstrating the accurate readout of the series resonant frequency and quality factor over an interrogation distance of up to 2 cm. As an application, the technique has been applied to the measurement of liquid microdroplets deposited on a 4.8 MHz AT-cut quartz crystal. More generally, the proposed technique can be exploited for the measurement of any physical or chemical quantities affecting the resonant response of quartz resonator sensors.<\/jats:p>","DOI":"10.3390\/s17061264","type":"journal-article","created":{"date-parts":[[2017,6,2]],"date-time":"2017-06-02T10:20:44Z","timestamp":1496398844000},"page":"1264","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":28,"title":["Analysis and Validation of Contactless Time-Gated Interrogation Technique for Quartz Resonator Sensors"],"prefix":"10.3390","volume":"17","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-5696-4138","authenticated-orcid":false,"given":"Marco","family":"Ba\u00f9","sequence":"first","affiliation":[{"name":"Department of Information Engineering, University of Brescia, Via Branze 38, Brescia 25123, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3310-7715","authenticated-orcid":false,"given":"Marco","family":"Ferrari","sequence":"additional","affiliation":[{"name":"Department of Information Engineering, University of Brescia, Via Branze 38, Brescia 25123, Italy"},{"name":"INO-CNR (National Research Council), Via Branze 45, Brescia 25123, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3949-9975","authenticated-orcid":false,"given":"Vittorio","family":"Ferrari","sequence":"additional","affiliation":[{"name":"Department of Information Engineering, University of Brescia, Via Branze 38, Brescia 25123, Italy"},{"name":"INO-CNR (National Research Council), Via Branze 45, Brescia 25123, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2017,6,2]]},"reference":[{"key":"ref_1","unstructured":"Vig, J.R. (2017, May 29). Introduction to Quartz Frequency Standards. Available online: https:\/\/ieee-uffc.org\/frequency-control\/learning-resources\/introduction-to-quartz-frequency-standards-by-john-r-vig\/."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/0924-4247(95)00846-2","article-title":"Sensors based on piezoelectric resonators","volume":"48","author":"Benes","year":"1995","journal-title":"Sens. Actuators A Phys."},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Ballantine, D.S., White, R.M., Martin, S.J., Ricco, A.J., Zellers, E.T., Frye, G.C., Wohltjen, H., Levy, M., and Stern, R. (1997). Acoustic wave sensors and responses. Acoustic Wave Sensors: Theory, Design, and Physico-Chemical Applications, Academic Press.","DOI":"10.1016\/B978-012077460-9\/50003-4"},{"key":"ref_4","unstructured":"Arnau, A. (2008). Overview of acoustic-wave microsensors. Piezoelectric Transducers and Applications, Springer. [2nd ed.]."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"371","DOI":"10.1016\/0924-4247(96)80161-0","article-title":"Extensions of the quartz-crystal-microbalance technique","volume":"53","author":"Mecea","year":"1996","journal-title":"Sens. Actuators A Phys."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"689","DOI":"10.1016\/j.tibtech.2009.09.003","article-title":"Acoustic wave biosensors: Physical models and biological applications of quartz crystal microbalance","volume":"27","author":"Ferreira","year":"2009","journal-title":"Trends Biotechnol."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"4004","DOI":"10.1002\/1521-3773(20001117)39:22<4004::AID-ANIE4004>3.0.CO;2-2","article-title":"Piezoelectric mass-sensing devices as biosensors\u2014An alternative to optical biosensors?","volume":"39","author":"Janshoff","year":"2000","journal-title":"Angew. Chem. Int. Ed."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"313","DOI":"10.1002\/1616-8984(200105)9:1<313::AID-SEUP313>3.0.CO;2-E","article-title":"Quartz Crystal Microbalance for Bioanalytical Applications","volume":"9","author":"Janshoff","year":"2001","journal-title":"Sens. Update"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"1355","DOI":"10.1021\/cr00014a006","article-title":"Measurement of interfacial processes at electrode surfaces with the electrochemical quartz crystal microbalance","volume":"92","author":"Buttry","year":"1992","journal-title":"Chem. Rev."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"124005","DOI":"10.1088\/0957-0233\/20\/12\/124005","article-title":"An oscillator circuit for dual-harmonic tracking of frequency and resistance in quartz resonator sensors","volume":"20","author":"Ferrari","year":"2009","journal-title":"Meas. Sci. Technol."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"489","DOI":"10.1016\/j.snb.2009.12.001","article-title":"Interface Circuit for Multiple-Harmonic Analysis on Quartz Resonator Sensors to Investigate on Liquid Solution Microdroplets","volume":"146","author":"Ferrari","year":"2009","journal-title":"Sens. Actuators B Chem."},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Sell, J.K.A., Niedermayer, O., and Jakoby, B. (2012, January 13\u201316). Reactance-locked loop for driving resonant sensors. Proceedings of the 2012 IEEE International Instrumentation and Measurement Technology Conference, Graz, Austria.","DOI":"10.1109\/I2MTC.2012.6229687"},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Lucklum, R., Doerner, S., Schneider, T., Schlatt-Masuth, B., Jacobs, T., and Hauptmann, P. (2006, January 4\u20137). Real Time Kinetic Analysis with Quartz Crystal Resonator Sensors. Proceedings of the 2006 IEEE International Frequency Control Symposium and Exposition, Miami, FL, USA.","DOI":"10.1109\/FREQ.2006.275441"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"3924","DOI":"10.1063\/1.1145396","article-title":"Quartz crystal microbalance setup for frequency and Q-factor measurements in gaseous and liquid environments","volume":"66","author":"Rodahl","year":"1995","journal-title":"Rev. Sci. Instrum."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"085023","DOI":"10.1088\/0964-1726\/18\/8\/085023","article-title":"An autonomous battery-less sensor module powered by piezoelectric energy harvesting with RF transmission of multiple measurement signals","volume":"18","author":"Ferrari","year":"2009","journal-title":"Smart Mater. Struct."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"99","DOI":"10.1109\/TIM.2008.928405","article-title":"Characterization of thermoelectric modules for powering autonomous sensors","volume":"58","author":"Dalola","year":"2009","journal-title":"IEEE Trans. Instrum. Meas."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"2","DOI":"10.1016\/j.snb.2007.07.007","article-title":"Flexible tag microlab development: Gas sensors integration in RFID flexible tags for food logistic","volume":"127","author":"Abad","year":"2007","journal-title":"Sens. Actuators B Chem."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"317","DOI":"10.1109\/58.827416","article-title":"A review of wireless SAW sensors","volume":"47","author":"Pohl","year":"2000","journal-title":"IEEE Trans. Ultrason. Ferroelectr."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1161","DOI":"10.1109\/58.726439","article-title":"Wireless sensing using oscillator circuits locked to remote high-Q SAW resonators","volume":"45","author":"Pohl","year":"1998","journal-title":"IEEE Trans. Ultrason. Ferroelectr."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"6903","DOI":"10.1021\/ac061004a","article-title":"Isolated electrodeless high-frequency quartz crystal microbalance for immunosensors","volume":"78","author":"Ogi","year":"2006","journal-title":"Anal. Chem."},{"key":"ref_21","unstructured":"Volpe, L.S., Ferrari, M., Ferrari, V., Arnau-Vives, A., and Perrot, H. (November, January 30). Contactless confined readout of quartz crystal resonator sensors. Proceedings of the 2005 IEEE Sensor, Irvine, CA, USA."},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Wu, W., Greve, D.W., and Oppenheimer, I.J. (2008, January 2\u20135). Inductively coupled sensing using a quartz crystal microbalance. Proceedings of the 2008 IEEE Ultrasonics Symposium, Beijing, China.","DOI":"10.1109\/ULTSYM.2008.0246"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"100","DOI":"10.1016\/j.sna.2013.04.029","article-title":"Piezoelectric resonant sensors with contactless interrogation for mass-sensitive and acoustic-load detection","volume":"202","author":"Ferrari","year":"2013","journal-title":"Sens. Actuators A Phys."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"195","DOI":"10.1016\/j.sna.2011.06.021","article-title":"Contactless electromagnetic switched interrogation of micromechanical cantilever resonators","volume":"172","author":"Tonoli","year":"2011","journal-title":"Sens. Actuators A Phys."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"294","DOI":"10.1166\/sl.2013.2724","article-title":"Contactless Time-Gated Technique for Electromagnetic Interrogation of Micromechanical Resonator Sensors","volume":"11","author":"Tonoli","year":"2013","journal-title":"Sens. Lett."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"187","DOI":"10.1109\/JSSC.2015.2470552","article-title":"A 30 ppm < 80 nJ Ring-Down-Based Readout Circuit for Resonant Sensors","volume":"51","author":"Jiang","year":"2016","journal-title":"IEEE J. Solid State Circuits"},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Ferrari, M., Ba\u00f9, M., Pagnoni, M., and Ferrari, V. (2014, January 2\u20135). Compact DDS-Based System for Contactless Interrogation of Resonant Sensors Based on Time-Gated Technique. Proceedings of the 2014 IEEE Sensors Conference, Valencia, Spain.","DOI":"10.1109\/ICSENS.2014.6985148"},{"key":"ref_28","unstructured":"Royer, D., and Dieulesaint, E. (2000). Piezoelectric transducers for bulk waves. Elastic Waves in Solids, Springer."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"704","DOI":"10.1016\/j.proeng.2016.11.252","article-title":"A Time-Gated Contactless Interrogation System for Frequency and Quality Factor Tracking in QCR to Investigate on Liquid Solution Microdroplets","volume":"168","author":"Ferrari","year":"2016","journal-title":"Procedia Eng."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/17\/6\/1264\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T18:37:47Z","timestamp":1760207867000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/17\/6\/1264"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2017,6,2]]},"references-count":29,"journal-issue":{"issue":"6","published-online":{"date-parts":[[2017,6]]}},"alternative-id":["s17061264"],"URL":"https:\/\/doi.org\/10.3390\/s17061264","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2017,6,2]]}}}