{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,22]],"date-time":"2026-01-22T18:24:11Z","timestamp":1769106251929,"version":"3.49.0"},"reference-count":35,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2018,8,9]],"date-time":"2018-08-09T00:00:00Z","timestamp":1533772800000},"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>In this study, a portable urea sensor that monitors the urea concentration in flow conditions was fabricated. We propose an electrochemical sensor that continually measures the urea concentration of samples flowing through it at a constant flow rate in real time. For the electrochemical sensing, a porous silk fibroin membrane with immobilized urease was mounted in a polydimethylsiloxane (PDMS) sensor housing. The fabricated urea sensor elicited linear current\u2013concentration characteristics in the clinically significant concentration range (0.1\u201320 mM) based on peritoneal dialysis. The sensor maintained the linear current\u2013concentration characteristics during operation in flow conditions.<\/jats:p>","DOI":"10.3390\/s18082607","type":"journal-article","created":{"date-parts":[[2018,8,9]],"date-time":"2018-08-09T10:36:31Z","timestamp":1533810991000},"page":"2607","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":30,"title":["Fabrication of a Urea Biosensor for Real-Time Dynamic Fluid Measurement"],"prefix":"10.3390","volume":"18","author":[{"given":"Kyunghee","family":"Kim","sequence":"first","affiliation":[{"name":"Cooperative Course of Nano-Medical Device Engineering, Hallym University, Chuncheon 24252, Korea"},{"name":"Department of Materials Science and Engineering, Hallym University, Chuncheon 24252, Korea"},{"name":"Integrative Materials Research Institute, Hallym University, Chuncheon 24252, Korea"}]},{"given":"Jeongeun","family":"Lee","sequence":"additional","affiliation":[{"name":"Cooperative Course of Nano-Medical Device Engineering, Hallym University, Chuncheon 24252, Korea"},{"name":"Department of Materials Science and Engineering, Hallym University, Chuncheon 24252, Korea"},{"name":"Integrative Materials Research Institute, Hallym University, Chuncheon 24252, Korea"}]},{"given":"Bo Mi","family":"Moon","sequence":"additional","affiliation":[{"name":"Nano-Bio Regenerative Medical Institute, College of Medicine, Hallym University, Chuncheon 24252, Korea"}]},{"given":"Ye Been","family":"Seo","sequence":"additional","affiliation":[{"name":"Nano-Bio Regenerative Medical Institute, College of Medicine, Hallym University, Chuncheon 24252, Korea"}]},{"given":"Chan Hum","family":"Park","sequence":"additional","affiliation":[{"name":"Nano-Bio Regenerative Medical Institute, College of Medicine, Hallym University, Chuncheon 24252, Korea"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3546-7834","authenticated-orcid":false,"given":"Min","family":"Park","sequence":"additional","affiliation":[{"name":"Cooperative Course of Nano-Medical Device Engineering, Hallym University, Chuncheon 24252, Korea"},{"name":"Department of Materials Science and Engineering, Hallym University, Chuncheon 24252, Korea"},{"name":"Integrative Materials Research Institute, Hallym University, Chuncheon 24252, Korea"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8515-4786","authenticated-orcid":false,"given":"Gun Yong","family":"Sung","sequence":"additional","affiliation":[{"name":"Cooperative Course of Nano-Medical Device Engineering, Hallym University, Chuncheon 24252, Korea"},{"name":"Department of Materials Science and Engineering, Hallym University, Chuncheon 24252, Korea"},{"name":"Integrative Materials Research Institute, Hallym University, Chuncheon 24252, Korea"}]}],"member":"1968","published-online":{"date-parts":[[2018,8,9]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"4617","DOI":"10.1073\/pnas.071057598","article-title":"Correlation of breath ammonia with blood urea nitrogen and creatinine during hemodialysis","volume":"98","author":"Narasimhan","year":"2001","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_2","unstructured":"Kaneko, H., Negishi, A., and Nozaki, K. (1996). Carbon Sensor Electrode and Process for Producing the Same. (5,503,728), U.S. Patent."},{"key":"ref_3","first-page":"511","article-title":"Chronic kidney disease in Korea","volume":"76","author":"Chin","year":"2009","journal-title":"Korean J. Med."},{"key":"ref_4","first-page":"525","article-title":"Chronic kidney disease","volume":"28","author":"Haynes","year":"2010","journal-title":"Surgery"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1238","DOI":"10.1016\/S0140-6736(16)32064-5","article-title":"Chronic Kidney Disease","volume":"389","author":"Webster","year":"2017","journal-title":"Lancet"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"562","DOI":"10.5124\/jkma.2013.56.7.562","article-title":"Current status of dialysis therapy for ESRD patients in Korea","volume":"56","author":"Jin","year":"2013","journal-title":"J. Korean Med. Assoc."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"20","DOI":"10.23876\/j.krcp.2018.37.1.20","article-title":"Current characteristics of dialysis therapy in Korea: 2016 registry data focusing on diabetic patients","volume":"37","author":"Jin","year":"2018","journal-title":"Kidney Res. Clin. Pract."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"9","DOI":"10.1016\/j.krcp.2014.01.002","article-title":"Renal replacement therapy in Korea, 2012","volume":"33","author":"Jin","year":"2014","journal-title":"Kidney Res. Clin. Pract."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"132","DOI":"10.1016\/j.krcp.2015.08.004","article-title":"Lessons from 30 years\u2019 data of Korean end-stage renal disease registry, 1985\u20132015","volume":"34","author":"Jin","year":"2015","journal-title":"Kidney Res. Clin. Pract."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"157","DOI":"10.1016\/j.aca.2005.03.069","article-title":"Enzyme coated glass pH-electrode: Its fabrication and applications in the determination of urea in blood samples","volume":"542","author":"Sahney","year":"2005","journal-title":"Anal. Chim. Acta"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"472","DOI":"10.1016\/j.snb.2017.05.048","article-title":"Fabrication of a highly effective electrochemical urea sensing platform based on urease-immobilized silk fibroin scaffold and aminated glassy carbon electrode","volume":"251","author":"Rafiq","year":"2017","journal-title":"Sens. Actuators B Chem."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"637","DOI":"10.1016\/j.snb.2011.08.041","article-title":"Selective determination of urea using urease immobilized on ZnO nanowires","volume":"160","author":"Ali","year":"2011","journal-title":"Sens. Actuators B Chem."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"33","DOI":"10.1016\/S0956-5663(98)00103-1","article-title":"A disposable biosensor for urea determination in blood based on an ammonium-sensitive transducer","volume":"14","author":"Eggenstein","year":"1999","journal-title":"Biosens. Bioelectron."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"3683","DOI":"10.1016\/j.biomaterials.2004.09.024","article-title":"An amperometric urea biosensor based on covalent immobilization of urease onto an electrochemically prepared copolymer poly (N-3-aminopropyl pyrrole-co-pyrrole) film","volume":"26","author":"Bisht","year":"2005","journal-title":"Biomaterials"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1597","DOI":"10.1002\/elan.200703889","article-title":"Electrochemical determination of ascorbic acid in room temperature ionic liquid BPPF6 modified carbon paste electrode","volume":"19","author":"Sun","year":"2007","journal-title":"Electroanalysis"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"90","DOI":"10.1016\/j.msec.2010.08.001","article-title":"Potentiometric urea biosensor based on multi-walled carbon nanotubes (MWCNTs)\/silica composite material","volume":"31","author":"Ahuja","year":"2011","journal-title":"Mater. Sci. Eng. C"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"231","DOI":"10.1016\/j.surfcoat.2004.10.022","article-title":"A novel thin film urea biosensor based on copolymer poly (N-3-aminopropylpyrrole-co-pyrrole) film","volume":"198","author":"Bisht","year":"2005","journal-title":"Surf. Coat. Technol."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"4139","DOI":"10.1016\/j.bios.2011.04.009","article-title":"Urea potentiometric enzymatic biosensor based on charged biopolymers and electrodeposited polyaniline","volume":"26","author":"Lakard","year":"2011","journal-title":"Biosens. Bioelectron."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"2164","DOI":"10.1021\/ja01036a083","article-title":"Urea-specific enzyme electrode","volume":"91","author":"Guilbault","year":"1969","journal-title":"J. Am. Chem. Soc."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/0956-5663(96)83708-0","article-title":"Amperometric ammonium ion and urea determination with enzyme-based probes","volume":"11","author":"Bertocchi","year":"1996","journal-title":"Biosens. Bioelectron."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"109","DOI":"10.1007\/s13206-016-1203-7","article-title":"Microfluidic biochips for simple impedimetric detection of thrombin based on label-free DNA aptamers","volume":"11","author":"Lim","year":"2017","journal-title":"BioChip J."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"111","DOI":"10.1007\/s13206-016-0205-9","article-title":"Screening for kidney malfunction using injection moulded plastic urinalysis cartridge","volume":"10","author":"Hong","year":"2016","journal-title":"BioChip J."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"42","DOI":"10.1016\/j.bej.2008.07.004","article-title":"Recent developments in urea biosensors","volume":"44","author":"Dhawan","year":"2009","journal-title":"Biochem. Eng. J."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"540","DOI":"10.1016\/j.bpc.2006.11.004","article-title":"Direct electrochemistry and electrocatalytic activity of catalase immobilized onto electrodeposited nano-scale islands of nickel oxide","volume":"125","author":"Salimi","year":"2007","journal-title":"Biophys. Chem."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"110","DOI":"10.1016\/j.bios.2012.07.062","article-title":"NiO nanoparticle-based urea biosensor","volume":"41","author":"Tyagi","year":"2013","journal-title":"Biosens. Bioelectron."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"15","DOI":"10.1016\/j.bios.2003.11.028","article-title":"Urea biosensor based on PANi (urease)-Nafion\u00ae\/Au composite electrode","volume":"20","author":"Luo","year":"2004","journal-title":"Biosens. Bioelectron."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"102","DOI":"10.1016\/j.snb.2005.08.027","article-title":"Amperometric ammonium ion sensor based on polyaniline-poly (styrene sulfonate-co-maleic acid) composite conducting polymeric electrode","volume":"115","author":"Luo","year":"2006","journal-title":"Sens. Actuators B Chem."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"46","DOI":"10.1016\/j.bios.2012.04.031","article-title":"Bi-enzyme l-arginine-selective amperometric biosensor based on ammonium-sensing polyaniline-modified electrode","volume":"37","author":"Stasyuk","year":"2012","journal-title":"Biosens. Bioelectron."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1080\/00032719408006342","article-title":"Micro Enzyme-sensor with osmium complex and a porous carbon for measuring uric acid","volume":"27","author":"Motonaka","year":"1994","journal-title":"Anal. Lett."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"1268","DOI":"10.1007\/s13233-014-2177-8","article-title":"Fabrication and Characterization of Three-Dimensional Silk Fibroin Scaffolds Using a Mixture of Salt\/Sucrose","volume":"22","author":"Moon","year":"2014","journal-title":"Macromol. Res."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"489","DOI":"10.1016\/j.biotechadv.2011.09.003","article-title":"Immobilization strategies to develop enzymatic biosensors","volume":"30","author":"Sassolas","year":"2012","journal-title":"Biotechnol. Adv."},{"key":"ref_32","doi-asserted-by":"crossref","unstructured":"Mishra, N., Devnani, H., and Bahadur, A. (2015). Immobilization of urease in alginate beads for urea estimation. Research, 2.","DOI":"10.13070\/rs.en.2.1328"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"763","DOI":"10.1016\/S0039-9140(01)00331-9","article-title":"Urea biosensor based on amperometric pH-sensing with hematein as a pH-sensitive redox mediator","volume":"54","author":"Pizzariello","year":"2001","journal-title":"Talanta"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"290","DOI":"10.1016\/j.snb.2013.12.098","article-title":"Highly stable urea sensor based on ZnO nanorods directly grown on Ag\/glass electrodes","volume":"194","author":"Ahmed","year":"2014","journal-title":"Sens. Actuators B Chem."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"372","DOI":"10.1016\/j.bios.2015.09.046","article-title":"Nickel\/cobalt oxide-decorated 3D graphene nanocomposite electrode for enhanced electrochemical detection of urea","volume":"77","author":"Nguyen","year":"2016","journal-title":"Biosens. Bioelectron."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/18\/8\/2607\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T15:17:39Z","timestamp":1760195859000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/18\/8\/2607"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2018,8,9]]},"references-count":35,"journal-issue":{"issue":"8","published-online":{"date-parts":[[2018,8]]}},"alternative-id":["s18082607"],"URL":"https:\/\/doi.org\/10.3390\/s18082607","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2018,8,9]]}}}