{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,13]],"date-time":"2026-01-13T02:22:42Z","timestamp":1768270962612,"version":"3.49.0"},"reference-count":26,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2011,4,27]],"date-time":"2011-04-27T00:00:00Z","timestamp":1303862400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/3.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>In this study, the urea-enzymatic field effect transistors (EnFETs) were investigated based on pH-ion sensitive field effect transistors (ISFETs) with tantalum pentoxide (Ta2O5) sensing membranes. In addition, a post N2 annealing was used to improve the sensing properties. At first, the pH sensitivity, hysteresis, drift, and light induced drift of the ISFETs were evaluated. After the covalent bonding process and urease immobilization, the urea sensitivity of the EnFETs were also investigated and compared with the conventional Si3N4 sensing layer. The ISFETs and EnFETs with annealed Ta2O5 sensing membranes showed the best responses, including the highest pH sensitivity (56.9 mV\/pH, from pH 2 to pH 12) and also corresponded to the highest urea sensitivity (61 mV\/pCurea, from 1 mM to 7.5 mM). Besides, the non-ideal factors of pH hysteresis, time drift, and light induced drift of the annealed samples were also lower than the controlled Ta2O5 and Si3N4 sensing membranes.<\/jats:p>","DOI":"10.3390\/s110504562","type":"journal-article","created":{"date-parts":[[2011,4,27]],"date-time":"2011-04-27T11:24:04Z","timestamp":1303903444000},"page":"4562-4571","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":38,"title":["Optimization of Urea-EnFET Based on Ta2O5 Layer with Post Annealing"],"prefix":"10.3390","volume":"11","author":[{"given":"Cheng-En","family":"Lue","sequence":"first","affiliation":[{"name":"Department of Electronic Engineering, Chang Gung University, 259 Wen-Hwa 1 st road,Kwei-Shan, Tao-Yuan, 333, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ting-Chun","family":"Yu","sequence":"additional","affiliation":[{"name":"Department of Electronic Engineering, Chang Gung University, 259 Wen-Hwa 1 st road,Kwei-Shan, Tao-Yuan, 333, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Chia-Ming","family":"Yang","sequence":"additional","affiliation":[{"name":"Device Section, Department of WAT and Devices, Inotera Memories Inc., 667 Fuhsing 3rd Road, Hwa-Ya Technology Park, Kwei-Shan, Tao-Yuan, 333, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Dorota G.","family":"Pijanowska","sequence":"additional","affiliation":[{"name":"Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Ul. Ks. Trojdena 4, 02-109 Warsaw, Poland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Chao-Sung","family":"Lai","sequence":"additional","affiliation":[{"name":"Department of Electronic Engineering, Chang Gung University, 259 Wen-Hwa 1 st road,Kwei-Shan, Tao-Yuan, 333, Taiwan"},{"name":"Biosensor Group, Biomedical Engineering Research Center, Chang Gung University, 259 Wen-Hwa 1 st road, Kwei-Shan, Tao-Yuan, 333, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2011,4,27]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1935","DOI":"10.1021\/ac50062a035","article-title":"Field effect transistor sensitive to penicillin","volume":"52","author":"Caras","year":"1980","journal-title":"Anal. Chem"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"370","DOI":"10.1016\/S0925-4005(97)00194-9","article-title":"pH-ISFET based urea biosensor","volume":"44","author":"Pijanowska","year":"1997","journal-title":"Sens. Actuat. B"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"283","DOI":"10.1016\/S0956-5663(99)00007-X","article-title":"Application of enzyme field-effect transistors for determination of glucose concentrations in blood serum","volume":"14","author":"Dzyadevich","year":"1999","journal-title":"Biosens. Bioelectron"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"351","DOI":"10.1016\/S0039-9140(02)00283-7","article-title":"Creatinine sensitive biosensor based on ISFETs and creatinine deiminase immobilised in BSA membrane","volume":"58","author":"Soldatkin","year":"2002","journal-title":"Talanta"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"485","DOI":"10.1109\/TBME.1974.324338","article-title":"An integrated field-effect electrode for biopotential recording","volume":"21","author":"Matsuo","year":"1974","journal-title":"IEEE Trans. Biomed. Eng"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"157","DOI":"10.1016\/0925-4005(94)87044-6","article-title":"Comparison of the hysteresis of Ta2O5 and Si3N4 pH-sensing insulators","volume":"17","author":"Bousse","year":"1994","journal-title":"Sens. Actuat. B"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"75","DOI":"10.1016\/0925-4005(91)85010-G","article-title":"Chemical sensitivity of an ISFET with Ta2O5 membrane in strong acid and alkaline solutions","volume":"3","author":"Bobrov","year":"1991","journal-title":"Sens. Actuat. B"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"441","DOI":"10.1016\/S0925-4005(96)01938-7","article-title":"Effects of heat treatment on Ta2O5 sensing membrane for low drift and high sensitivity pH-ISFET","volume":"34","author":"Kwon","year":"1996","journal-title":"Sens. Actuat. B"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"152","DOI":"10.1016\/S0925-4005(99)00499-2","article-title":"Long-term drift mechanism of Ta2O5 gate pH-ISFETs","volume":"64","author":"Ito","year":"2000","journal-title":"Sens. Actuat. B"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"120","DOI":"10.1016\/S0254-0584(00)00513-7","article-title":"Sensitivity and hysteresis effect in Al2O3 gate pH-ISFET","volume":"71","author":"Chou","year":"2001","journal-title":"Mater. Chem. Phys"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"214","DOI":"10.1016\/S0169-4332(03)00340-4","article-title":"The pH-sensing and light-induced drift properties of titanium dioxide thin films deposited by MOCVD","volume":"214","author":"Shin","year":"2003","journal-title":"Appl. Surf. Sci"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"157","DOI":"10.1016\/j.tsf.2004.09.061","article-title":"Study on pH at the point of zero charge of TiO2 pH ion-sensitive field effect transistor made by the sputtering method","volume":"476","author":"Chou","year":"2005","journal-title":"Thin Solid Film"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"G90","DOI":"10.1149\/1.2163550","article-title":"pH sensitivity improvement on 8 nm thick hafnium oxide by post deposition annealing","volume":"9","author":"Lai","year":"2006","journal-title":"Electrochem. Solid-State Lett"},{"key":"ref_14","unstructured":"van der Wal, PD, Briand, D, Mondin, G, Jenny, S, Jeanneret, S, Millon, C, Roussel, H, Dubourdieu, C, and de Rooij, NF (2004, January 24\u201327). High-k dielectrics for use as ISFET gate oxides. Vienna, Austria."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"58","DOI":"10.1016\/S0925-4005(02)00147-8","article-title":"Preparation and study on the drift and hysteresis properties of the tin oxide gate ISFET by the sol-gel method","volume":"86","author":"Chou","year":"2002","journal-title":"Sens. Actuat. B"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"75","DOI":"10.1016\/0925-4005(91)85010-G","article-title":"Chemical sensitivity of an ISFET with Ta2O5 membrane","volume":"3","author":"Bobrov","year":"1991","journal-title":"Sens. Actuat. B"},{"key":"ref_17","first-page":"423","article-title":"CIP (cleaning-in-place) suitable \u201cnon-glass\u201d pH sensor based on a Ta2O5-gate EIS structure","volume":"111\u2013112","author":"Brinkmann","year":"2005","journal-title":"Sens Actuat B"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"2384","DOI":"10.1016\/j.bios.2008.12.012","article-title":"Glutamate sensing with enzyme-modified floating-gate field effect transistors","volume":"24","author":"Braeken","year":"2009","journal-title":"Biosens. Bioelectron"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"7539","DOI":"10.1143\/JJAP.46.7539","article-title":"Molecular commonality sensing of phosphoric anhydride substances using an ion-sensitive field-effect transistor covered with an artificial enzyme membrane","volume":"46","author":"Migita","year":"2007","journal-title":"Jpn. J. Appl. Phys, Part 1"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"350","DOI":"10.1016\/0925-4005(90)80228-R","article-title":"Photoelectric effects in Ta2O5-SiO2-Si structures","volume":"B1","author":"Voorthuyzen","year":"1990","journal-title":"Sens. Actuat"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"262","DOI":"10.1016\/S0925-4005(97)00166-4","article-title":"The pH-sensing properties of tantalum pentoxide filmes fabricated by metal organic low pressure chemical vapor depostition","volume":"44","author":"Mikolajick","year":"1997","journal-title":"Sens. Actuat. B"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"146","DOI":"10.3390\/s30600146","article-title":"An influence of polyHEMA gate layer on properties of ChemFETs","volume":"3","author":"Dawgul","year":"2003","journal-title":"Sensors"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"2076","DOI":"10.3390\/s90302076","article-title":"Optimization of a PVC Membrane for Reference Field Effect Transistors","volume":"9","author":"Lai","year":"2009","journal-title":"Sensors"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"77","DOI":"10.1016\/j.snb.2007.07.115","article-title":"New pH-sensitive TaOxNy membranes prepared by NH3 plasma surface treatment and nitrogen incorporated reactive sputtering","volume":"130","author":"Lai","year":"2008","journal-title":"Sens. Actuat. B"},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Lai, C-S, Lue, C-E, Yang, C-M, and Jao, J-H (2006, January 12\u201315). Modifications on pH Sensitivitiy of Si3N4 Membrane by CF4 Plasma and Rapid Thermal Annealing for ISFET\/REFET Applications. Yokohama, Japan.","DOI":"10.7567\/SSDM.2006.P-11-5"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"309","DOI":"10.1016\/S0925-4005(03)00430-1","article-title":"Development of chemical field effect transistors for detection of urea","volume":"95","author":"Sant","year":"2004","journal-title":"Sens. Actuat. B"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/11\/5\/4562\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T21:55:56Z","timestamp":1760219756000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/11\/5\/4562"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2011,4,27]]},"references-count":26,"journal-issue":{"issue":"5","published-online":{"date-parts":[[2011,5]]}},"alternative-id":["s110504562"],"URL":"https:\/\/doi.org\/10.3390\/s110504562","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2011,4,27]]}}}