title: Urea biosensor based on an extended-base bipolar junction transistor.
abstract: In this study, a urea biosensor was prepared by the immobilization of urease onto the sensitive membrane of an extended-base bipolar junction transistor. The pH variation was used to detect the concentration of urea. The SnO2/ITO glass, fabricated by sputtering SnO2 on the conductive ITO glass, was used as a pH-sensitive membrane, which was connected with a commercial bipolar junction transistor device. The gels, fabricated by the poly vinyl alcohol with pendent styrylpyridinium groups, were used to immobilize the urease. This readout circuit, fabricated in a 0.35-um CMOS 2P4M process, operated at 3.3V supply voltage. This circuit occupied an area of 1.0 mm × 0.9 mm. The dynamic range of the urea biosensor was from 1.4 to 64 mg/dl at the 10 mM phosphate buffer solution and the sensitivity of this range was about 65.8 mV/pUrea. The effect of urea biosensors with different pH values was considered, and the characteristics of urea biosensors based on EBBJT were described.
authors.affiliation: Institute of Electrical Engineering, National Chi Nan University, Nantou, 545, Taiwan, ROC.
authors.forename: Tai-Ping
authors.initials: TP
authors.lastname: Sun
authors.forename: Hsiu-Li
authors.initials: HL
authors.lastname: Shieh
authors.forename: Chun-Lin
authors.initials: CL
authors.lastname: Liu
authors.forename: Chung-Yuan
authors.initials: CY
authors.lastname: Chen
mesh_terms: D001698:Biomedical Engineering; D015374:Biosensing Techniques; D004563:Electrochemistry; D004581:Electronics; D004800:Enzymes, Immobilized / Q000737:chemistry; D004867:Equipment Design; D006863:Hydrogen-Ion Concentration; D008422:Materials Testing; D011142:Polyvinyl Alcohol; D011726:Pyridinium Compounds / Q000737:chemistry; D017971:Tin Compounds / Q000737:chemistry; D014508:Urea / Q000737:chemistry*; D014510:Urease / Q000737:chemistry
chemical_list: D004800:Enzymes, Immobilized; D011726:Pyridinium Compounds; D017971:Tin Compounds; D014508:Urea; D011142:Polyvinyl Alcohol; D014510:Urease; C045358:stannic oxide
keywords: CMOS; Extended-base bipolar junction transistor; ITO; SnO2; urea