{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,20]],"date-time":"2026-01-20T15:42:58Z","timestamp":1768923778477,"version":"3.49.0"},"reference-count":10,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2016,12,28]],"date-time":"2016-12-28T00:00:00Z","timestamp":1482883200000},"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>The paper aims to study the sensor that identifies the maturity of oil palm fruit bunches by using a flat-type inductive concept based on a resonant frequency technique. Conventionally, a human grader is used to inspect the ripeness of the oil palm fresh fruit bunch (FFB) which can be inconsistent and inaccurate. There are various new methods that are proposed with the intention to grade the ripeness of the oil palm FFB, but none has taken the inductive concept. In this study, the resonance frequency of the air coil is investigated. Samples of oil palm FFB are tested with frequencies ranging from 20 Hz to 10 MHz and the results obtained show a linear relationship between the graph of the resonance frequency (MHz) against time (Weeks). It is observed that the resonance frequencies obtained for Week 10 (pre-mature) and Week 18 (mature) are around 8.5 MHz and 9.8 MHz, respectively. These results are compared with the percentage of the moisture content. Hence, the inductive method of the oil palm fruit maturity sensor can be used to detect the change in water content for ripeness detection of the oil palm FFB.<\/jats:p>","DOI":"10.3390\/s17010052","type":"journal-article","created":{"date-parts":[[2016,12,28]],"date-time":"2016-12-28T11:22:14Z","timestamp":1482924134000},"page":"52","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":19,"title":["Relative Estimation of Water Content for Flat-Type Inductive-Based Oil Palm Fruit Maturity Sensor"],"prefix":"10.3390","volume":"17","author":[{"given":"Norhisam","family":"Misron","sequence":"first","affiliation":[{"name":"Faculty of Engineering, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia"},{"name":"Institute of Advance Technology (ITMA), Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8057-7915","authenticated-orcid":false,"given":"Nor","family":"Aliteh","sequence":"additional","affiliation":[{"name":"Faculty of Engineering, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Noor","family":"Harun","sequence":"additional","affiliation":[{"name":"Medical Engineering Section, Universiti Kuala Lumpur-British Malaysia Institute, Batu 8, Jalan Sg Pusu, 53100 Gombak, Selangor, Malaysia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kunihisa","family":"Tashiro","sequence":"additional","affiliation":[{"name":"Faculty of Engineering, Shinshu University, Wakasato 4-17-1, Nagano 380-8553, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Toshiro","family":"Sato","sequence":"additional","affiliation":[{"name":"Faculty of Engineering, Shinshu University, Wakasato 4-17-1, Nagano 380-8553, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hiroyuki","family":"Wakiwaka","sequence":"additional","affiliation":[{"name":"Faculty of Engineering, Shinshu University, Wakasato 4-17-1, Nagano 380-8553, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2016,12,28]]},"reference":[{"key":"ref_1","unstructured":"Malaysian Palm Oil Board (2003). Oil Palm Fruit Grading Manual, Malaysian Palm Oil Board (MPOB). [2nd ed.]."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"55","DOI":"10.1016\/j.compag.2011.12.010","article-title":"Classification of oil palm fresh fruit bunches based on their maturity using portable four-band sensor system","volume":"82","author":"Osama","year":"2012","journal-title":"Comput. Electron. Agric."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"7","DOI":"10.2478\/v10048-010-0002-x","article-title":"Application of microwave moisture sensor for determination of oil palm fruit ripeness","volume":"10","author":"Yeow","year":"2010","journal-title":"Meas. Sci. Rev."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"1281","DOI":"10.1109\/JSEN.2005.859249","article-title":"Complex permittivity and moisture measurements of oil palm fruits using an open-ended coaxial sensor","volume":"5","author":"Abbas","year":"2005","journal-title":"IEEE Sens. J."},{"key":"ref_5","first-page":"101","article-title":"Monitoring development and ripeness of oil palm fruit (Elaeis guineensis) by MRI and bulk NMR","volume":"12","author":"Sharifudin","year":"2010","journal-title":"Int. J. Agric. Biolog."},{"key":"ref_6","first-page":"1055","article-title":"Determination of palm oil residue in palm kernel and palm oil methyl ester using near infrared spectroscopy","volume":"23","author":"Bonnie","year":"2011","journal-title":"J. Oil Palm Res."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"671","DOI":"10.1109\/63.602562","article-title":"Self-capacitance of inductors","volume":"12","author":"Massarini","year":"1997","journal-title":"IEEE Trans. Power Electron."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"28","DOI":"10.1016\/j.sna.2003.08.005","article-title":"Physical sensors for water-in-oil emulsions","volume":"110","author":"Jakoby","year":"2004","journal-title":"Sens. Actuators A. Phys."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"2431","DOI":"10.3390\/s140202431","article-title":"Investigations on a novel inductive oil palm fruit sensor","volume":"14","author":"Harun","year":"2014","journal-title":"Sensors"},{"key":"ref_10","first-page":"119","article-title":"Experimental confirmation of cylindrical electromagnetic sensor design for liquid detection application","volume":"Volume 12","author":"Mason","year":"2015","journal-title":"Sensing Technology: Current Status and Future Trends IV"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/17\/1\/52\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T19:29:26Z","timestamp":1760210966000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/17\/1\/52"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2016,12,28]]},"references-count":10,"journal-issue":{"issue":"1","published-online":{"date-parts":[[2017,1]]}},"alternative-id":["s17010052"],"URL":"https:\/\/doi.org\/10.3390\/s17010052","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2016,12,28]]}}}