{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,3]],"date-time":"2026-06-03T09:02:12Z","timestamp":1780477332013,"version":"3.54.1"},"reference-count":30,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2018,12,10]],"date-time":"2018-12-10T00:00:00Z","timestamp":1544400000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100002369","name":"Chongqing University","doi-asserted-by":"publisher","award":["106112015CDJXY120007"],"award-info":[{"award-number":["106112015CDJXY120007"]}],"id":[{"id":"10.13039\/501100002369","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100002369","name":"Chongqing University","doi-asserted-by":"publisher","award":["106112017CDJQJ118846"],"award-info":[{"award-number":["106112017CDJQJ118846"]}],"id":[{"id":"10.13039\/501100002369","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100002369","name":"Chongqing University","doi-asserted-by":"publisher","award":["106112017CDJXSJW0007"],"award-info":[{"award-number":["106112017CDJXSJW0007"]}],"id":[{"id":"10.13039\/501100002369","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100002369","name":"Chongqing University","doi-asserted-by":"publisher","award":["10611CDJXZ238826"],"award-info":[{"award-number":["10611CDJXZ238826"]}],"id":[{"id":"10.13039\/501100002369","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100002855","name":"Ministry of Science and Technology of the People's Republic of China","doi-asserted-by":"publisher","award":["2016YFE0125200"],"award-info":[{"award-number":["2016YFE0125200"]}],"id":[{"id":"10.13039\/501100002855","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100002855","name":"Ministry of Science and Technology of the People's Republic of China","doi-asserted-by":"publisher","award":["2016YFC0101100"],"award-info":[{"award-number":["2016YFC0101100"]}],"id":[{"id":"10.13039\/501100002855","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001352","name":"National University of Singapore","doi-asserted-by":"publisher","award":["R263501012133"],"award-info":[{"award-number":["R263501012133"]}],"id":[{"id":"10.13039\/501100001352","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001348","name":"Agency for Science, Technology and Research","doi-asserted-by":"publisher","award":["R263000C91305"],"award-info":[{"award-number":["R263000C91305"]}],"id":[{"id":"10.13039\/501100001348","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>A novel relative humidity sensor that is based on a linear piezoelectric micromachined ultrasonic transducer (pMUT) array was proposed and microfabricated for high sensitivity, fast response, and good stability. The humidity-sensitive graphene oxide (GO) film was deposited on the pMUT array with a facile drop-casting method and characterized by scanning electron microscope (SEM), atomic force microscope (AFM), and Fourier transform infrared spectrum (FTIR). With the humidity level ranging from 10% to 90% RH, the sensor exhibited a high sensitivity of 719 Hz\/% RH and an extremely high relative sensitivity of 271.1 ppm\/% RH. The humidity-sensing results also showed good short-term repeatability and long-term stability, fast response and recovery, and low hysteresis. Moreover, the temperature coefficient of frequency (TCF) of the present humidity sensor was investigated and it could be easily compensated owing to the pMUT array structure design. This work confirmed that the GO functionalized pMUT is an excellent candidate in humidity detection and it may enable many potential applications, such as ultrasensitive mass detection and simultaneous detection of multiple parameters.<\/jats:p>","DOI":"10.3390\/s18124352","type":"journal-article","created":{"date-parts":[[2018,12,10]],"date-time":"2018-12-10T03:36:41Z","timestamp":1544413001000},"page":"4352","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":53,"title":["Development of a Highly Sensitive Humidity Sensor Based on a Piezoelectric Micromachined Ultrasonic Transducer Array Functionalized with Graphene Oxide Thin Film"],"prefix":"10.3390","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-5156-033X","authenticated-orcid":false,"given":"Changhe","family":"Sun","sequence":"first","affiliation":[{"name":"Centre for Intelligent Sensing Technology, College of Optoelectronic Engineering, Chongqing University, Chongqing 400044, China"},{"name":"Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117583, Singapore"},{"name":"Center for Intelligent Sensors and MEMS, National University of Singapore, E6 #05-11F, 5 Engineering Drive 1, Singapore 117608, Singapore"},{"name":"Key Laboratory of Optoelectronic Technology &amp; Systems (Chongqing University), Ministry of Education, Chongqing 400044, China"},{"name":"Collaborative Innovation Center for Brain Science, Chongqing University, Chongqing 400044, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Qiongfeng","family":"Shi","sequence":"additional","affiliation":[{"name":"Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117583, Singapore"},{"name":"Center for Intelligent Sensors and MEMS, National University of Singapore, E6 #05-11F, 5 Engineering Drive 1, Singapore 117608, Singapore"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1836-1974","authenticated-orcid":false,"given":"Mahmut Sami","family":"Yazici","sequence":"additional","affiliation":[{"name":"Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117583, Singapore"},{"name":"Center for Intelligent Sensors and MEMS, National University of Singapore, E6 #05-11F, 5 Engineering Drive 1, Singapore 117608, Singapore"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8886-3649","authenticated-orcid":false,"given":"Chengkuo","family":"Lee","sequence":"additional","affiliation":[{"name":"Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117583, Singapore"},{"name":"Center for Intelligent Sensors and MEMS, National University of Singapore, E6 #05-11F, 5 Engineering Drive 1, Singapore 117608, Singapore"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2988-8843","authenticated-orcid":false,"given":"Yufei","family":"Liu","sequence":"additional","affiliation":[{"name":"Centre for Intelligent Sensing Technology, College of Optoelectronic Engineering, Chongqing University, Chongqing 400044, China"},{"name":"Key Laboratory of Optoelectronic Technology &amp; Systems (Chongqing University), Ministry of Education, Chongqing 400044, China"},{"name":"Collaborative Innovation Center for Brain Science, Chongqing University, Chongqing 400044, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2018,12,10]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"7881","DOI":"10.3390\/s140507881","article-title":"Humidity sensors principle, mechanism, and fabrication technologies: A comprehensive review","volume":"14","author":"Farahani","year":"2014","journal-title":"Sensors"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"434","DOI":"10.1111\/1523-1747.ep12476467","article-title":"Comparison of the effects of moist and dry conditions on dermal repair","volume":"91","author":"Dyson","year":"1988","journal-title":"J. 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