{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,4]],"date-time":"2026-02-04T20:33:30Z","timestamp":1770237210061,"version":"3.49.0"},"reference-count":36,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2015,10,7]],"date-time":"2015-10-07T00:00:00Z","timestamp":1444176000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["21265006"],"award-info":[{"award-number":["21265006"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"name":"East China JiaoTong University Foundation","award":["14DQ08"],"award-info":[{"award-number":["14DQ08"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>This paper presents a wireless humidity sensor tag for low-cost and low-power applications. The proposed humidity sensor tag, based on radio frequency identification (RFID) technology, was fabricated in a standard 0.18 \u03bcm complementary metal oxide semiconductor (CMOS) process. The top metal layer was deposited to form the interdigitated electrodes, which were then filled with polyimide as the humidity sensing layer. A two-stage rectifier adopts a dynamic bias-voltage generator to boost the effective gate-source voltage of the switches in differential-drive architecture, resulting in a flat power conversion efficiency curve. The capacitive sensor interface, based on phase-locked loop (PLL) theory, employs a simple architecture and can work with 0.5 V supply voltage. The measurement results show that humidity sensor tag achieves excellent linearity, hysteresis and stability performance. The total power-dissipation of the sensor tag is 2.5 \u03bcW, resulting in a maximum operating distance of 23 m under 4 W of radiation power of the RFID reader.<\/jats:p>","DOI":"10.3390\/s151025564","type":"journal-article","created":{"date-parts":[[2015,10,7]],"date-time":"2015-10-07T10:39:13Z","timestamp":1444214353000},"page":"25564-25576","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":10,"title":["Design of a Humidity Sensor Tag for Passive  Wireless Applications"],"prefix":"10.3390","volume":"15","author":[{"given":"Xiang","family":"Wu","sequence":"first","affiliation":[{"name":"School of Electrical and Electronic Engineering, East China JiaoTong University, Nanchang 330013, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Fangming","family":"Deng","sequence":"additional","affiliation":[{"name":"School of Electrical and Electronic Engineering, East China JiaoTong University, Nanchang 330013, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yong","family":"Hao","sequence":"additional","affiliation":[{"name":"School of Mechatronic Engineering, East China JiaoTong University, Nanchang 330013, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Zhihui","family":"Fu","sequence":"additional","affiliation":[{"name":"School of Electrical and Electronic Engineering, East China JiaoTong University, Nanchang 330013, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Lihua","family":"Zhang","sequence":"additional","affiliation":[{"name":"School of Electrical and Electronic Engineering, East China JiaoTong University, Nanchang 330013, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2015,10,7]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"4140","DOI":"10.1364\/OE.19.004140","article-title":"Optical fiber relative humidity sensor based on FBG incorporated thin-core fiber modal interferometer","volume":"19","author":"Gu","year":"2011","journal-title":"Opt. Express"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"8847","DOI":"10.3390\/s120708847","article-title":"Optical fiber relative humidity sensor based on a FBG with a Di-ureasil coating","volume":"12","author":"Correia","year":"2012","journal-title":"Sensors"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"681","DOI":"10.1016\/j.snb.2010.08.020","article-title":"Humidity sensing characteristics of Ga-doped zinc oxide film grown on a polycrystalline AlN thin film based on a surface acoustic wave","volume":"150","author":"Hong","year":"2010","journal-title":"Sensor Actuators B Chem."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"16816","DOI":"10.3390\/s131216816","article-title":"Optimal design of a polyaniline-coated surface acoustic wave based humidity sensor","volume":"13","author":"Wang","year":"2013","journal-title":"Sensors"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"302","DOI":"10.1016\/j.snb.2009.09.004","article-title":"Design and optimization of an ultra thin flexible capacitive humidity sensor","volume":"143","author":"Zampetti","year":"2009","journal-title":"Sens. Actuators B Chem."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"3071","DOI":"10.1109\/TED.2007.907165","article-title":"A low-power robust humidity sensor in a standard CMOS process","volume":"54","author":"Okcan","year":"2007","journal-title":"IEEE Trans. Electron. Devices"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"75","DOI":"10.1016\/0925-4005(93)85030-E","article-title":"High sensitivity CMOS humidity sensors with on-chip absolute capacitance measurement system","volume":"15","author":"Boltshauser","year":"1993","journal-title":"Sens. Actuators B Chem."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"304","DOI":"10.1109\/TIM.2012.2216476","article-title":"A novel localization algorithm based on isomap and partial least squares for wireless sensor networks","volume":"62","author":"Li","year":"2013","journal-title":"IEEE Trans. Instrum. Meas."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"2387","DOI":"10.1109\/TIM.2013.2287119","article-title":"Metrics of the application environment impact to the passive UHF RFID system","volume":"63","author":"Li","year":"2014","journal-title":"IEEE Trans. Instrum. Meas."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"394","DOI":"10.1016\/j.jfoodeng.2009.02.004","article-title":"RFID smart tag for traceability and cold chain monitoring of foods: Demonstration in an intercontinental fresh fish logistic chain","volume":"93","author":"Abad","year":"2009","journal-title":"J. Food Eng."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"227","DOI":"10.1016\/j.snb.2009.04.019","article-title":"Temperature, humidity and gas sensors integrated on plastic foil for low power applications","volume":"140","author":"Oprea","year":"2009","journal-title":"Sens. Actuators B Chem."},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Beriain, A., Rebollo, I., Fernandez, I., Sevillano, J.F., and Berenguer, R. (2012, January 17\u201322). A passive UHF RFID pressure sensor tag with a 7.27 bit and 5.47 pj capacitive sensor interface. Proceedings of the 2012 IEEE International Microwave Symposium Digest (MTT), Montreal, PQ, Canada.","DOI":"10.1109\/MWSYM.2012.6258415"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"491","DOI":"10.1016\/j.snb.2003.12.060","article-title":"A novel capacitive-type humidity sensor using CMOS fabrication technology","volume":"99","author":"Gu","year":"2004","journal-title":"Sens. Actuators B Chem."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"2986","DOI":"10.1109\/JSEN.2011.2154325","article-title":"A fully packaged CMOS interdigital capacitive humidity sensor with polysilicon heaters","volume":"11","author":"Zhao","year":"2011","journal-title":"IEEE Sens. J."},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Kim, J.H., Hong, S.M., Lee, J.S., Moon, B.M., and Kim, K. (2009, January 5\u20138). High sensitivity capacitive humidity sensor with a novel polyimide design fabricated by MEMS technology. Proceeding of the 4th IEEE International Conference on Nano\/Micro Engineered and Molecular Systems (NEMS), Shenzhen, China.","DOI":"10.1109\/NEMS.2009.5068676"},{"key":"ref_16","unstructured":"Dai, C.L., and Lu, D.H. (2010, January 20\u201323). Fabrication of a micro humidity sensor with polypyrrole using the CMOS process. Proceedings of the 5th IEEE International Conference on Nano\/Micro Engineered and Molecular Systems, Nice, France."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"226","DOI":"10.3390\/s120100226","article-title":"Self-calibrated humidity sensor in CMOS without post-processing","volume":"12","author":"Nizhnik","year":"2012","journal-title":"Sensors"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"2469","DOI":"10.1109\/JSSC.2013.2275661","article-title":"A 1.2-V 8.3-nJ CMOS Humidity Sensor for RFID Applications","volume":"48","author":"Tan","year":"2013","journal-title":"IEEE J. Solid State Circuits"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"8728","DOI":"10.3390\/s140508728","article-title":"A CMOS humidity sensor for passive RFID sensing applications","volume":"14","author":"Deng","year":"2014","journal-title":"Sensors"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"900","DOI":"10.1109\/JSEN.2012.2217376","article-title":"Humidity-to-frequency sensor in CMOS technology with wireless readout","volume":"13","author":"Cirmirakis","year":"2013","journal-title":"IEEE Sens. J."},{"key":"ref_21","first-page":"189","article-title":"High-efficiency differential RF front-end for a Gen2 RFID tag","volume":"4","author":"Wei","year":"2011","journal-title":"IEEE Trans. Circuits Syst. II"},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Kapucu, K., and Dehollain, C. (2014, January 8\u20139). A passive UHF RFID system with a low-power capacitive sensor interface. Proceedings of the 2014 IEEE RFID Technology and Applications Conference (RFID-TA), Tampere, Finland.","DOI":"10.1109\/RFID-TA.2014.6934247"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"3870","DOI":"10.1109\/TAP.2005.859919","article-title":"Antenna design for UHF RFID tags: A review and a practical application","volume":"53","author":"Rao","year":"2005","journal-title":"IEEE Trans. Antennas Propag."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"1504","DOI":"10.1016\/j.mejo.2009.01.013","article-title":"A compact low-power UHF RFID tag","volume":"40","author":"Ashry","year":"2009","journal-title":"Microelectron. J."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"375","DOI":"10.1016\/j.snb.2006.05.042","article-title":"A capacitive humidity sensor integrated with micro heater and ring oscillator circuit fabricated by CMOS\u2013MEMS technique","volume":"122","author":"Dai","year":"2007","journal-title":"Sens. Actuators B Chem."},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Kamalinejad, P., Keikhosravy, K., Mirabbasi, S., and Leung, V. (2013, January 3\u20135). An efficiency enhancement technique for CMOS rectifiers with low start-up voltage for UHF RFID tags. Proceedings of the International Green Computing Conference (IGCC), Dallas, TX, USA.","DOI":"10.1109\/IGCC.2013.6604483"},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Theilmann, P.T., Presti, C.D., Kelly, D., and Asbeck, P.M. (2010, January 23\u201325). Near zero turn-on voltage high-efficiency UHF RFID rectifier in silicon-on-sapphire CMOS. Proceedings of the IEEE Radio Frequency Integrated Circuits Symposium (RFIC), Anaheim, CA, USA.","DOI":"10.1109\/RFIC.2010.5477409"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"1177","DOI":"10.1109\/TCSI.2007.895229","article-title":"Low-power CMOS rectifier design for RFID applications","volume":"54","author":"Mandal","year":"2007","journal-title":"IEEE Trans. Circuits Syst. I"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"3011","DOI":"10.1109\/JSSC.2009.2028955","article-title":"High-efficiency differential-drive CMOS rectifier for UHF RFIDs","volume":"44","author":"Kotani","year":"2009","journal-title":"IEEE J. Solid State Circuits"},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Kamalinejad, P., Keikhosravy, K., and Mirabbasi, S. (2013, January 4\u20135). A CMOS rectifier with an extended high-efficiency region of operation. Proceedings of the 2014 IEEE RFID Technology and Applications Conference (RFID-TA), Johor Bahru, Malaysia.","DOI":"10.1109\/RFID-TA.2013.6694527"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"3193","DOI":"10.1109\/JSSC.2009.2031059","article-title":"A micropower-based interface ASIC for a capacitive 3-axis micro-accelerometer","volume":"44","author":"Paavola","year":"2009","journal-title":"IEEE J. Solid State Circuits"},{"key":"ref_32","first-page":"90","article-title":"A delta\u2013sigma interface circuit for capacitive sensors with an automatically calibrated zero point","volume":"58","author":"Shin","year":"2011","journal-title":"IEEE Trans. Circuits System II"},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Nguyen, T.T., and Hafliger, P. (2013, January 1\u20132). An energy efficient inverter based readout circuit for capacitive sensor. Proceedings of the Biomedical Circuits and Systems Conference (BioCAS), Rotterdam, Netherlands.","DOI":"10.1109\/BioCAS.2013.6679705"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"447","DOI":"10.1109\/TIM.2011.2161929","article-title":"A capacitance-ratio-modulated current front-end circuit with pulsewidth modulation output for a capacitive sensor interface","volume":"61","author":"Sheu","year":"2012","journal-title":"IEEE Trans. Instrum. Meas."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"1703","DOI":"10.1109\/JSSC.2012.2191212","article-title":"An energy-efficient 15-bit capacitive-sensor interface based on period modulation","volume":"47","author":"Tan","year":"2012","journal-title":"IEEE J. Solid State Circuits"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"220","DOI":"10.1016\/j.sna.2011.04.047","article-title":"A novel PLL-based frequency-to-digital conversion mechanism for sensor interfaces","volume":"172","author":"Danneels","year":"2011","journal-title":"Sens. Actuators A Phys."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/15\/10\/25564\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T20:49:44Z","timestamp":1760215784000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/15\/10\/25564"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2015,10,7]]},"references-count":36,"journal-issue":{"issue":"10","published-online":{"date-parts":[[2015,10]]}},"alternative-id":["s151025564"],"URL":"https:\/\/doi.org\/10.3390\/s151025564","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2015,10,7]]}}}