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Development of an Ion Sensitive Field Effect Transistor Based Urea Biosensor with Solid State Reference Systems
Department of Electronics Engineering, Institute of Electronics, National Chiao Tung University, Hsinchu, 30050, Taiwan
* Author to whom correspondence should be addressed.
Received: 14 April 2010; in revised form: 25 May 2010 / Accepted: 1 June 2010 / Published: 21 June 2010
Abstract: Ion sensitive field-effect transistor (ISFET) based urease biosensors with solid state reference systems for single-ended and two-ended differential readout electronics were investigated. The sensing membranes of the biosensors were fabricated with urease immobilized in a conducting polymer-based matrix. The responses of 12.9~198.1 mV for the urea concentrations of 8~240 mg/dL reveal that the activity of the enzyme was not significantly decreased. Biosensors combined with solid state reference systems were fabricated, and the evaluation results demonstrated the feasibility of miniaturization. For the differential system, the optimal transconductance match for biosensor and reference field-effect transistors (REFET) pair was determined through the modification of the membranes of the REFETs and enzyme field-effect transistors (EnFETs). The results show that the transconductance curve of polymer based REFET can match with that of the EnFET by adjusting the photoresist/NafionTM ratio. The match of the transconductance curves for the differential pairs provides a wide dynamic operating measurement range. Accordingly, the miniaturized quasi-reference electrode (QRE)/REFET/EnFET combination with differential arrangement achieved similar urea response curves as those measured by a conventional large sized discrete sensor.
Keywords: ion sensitive field-effect transistors (ISFETs); reference field-effect transistors (REFETs); differential measurement; biosensor; enzyme field-effect transistors (EnFETs); transconductance-match
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MDPI and ACS Style
Chang, K.-M.; Chang, C.-T.; Chan, K.-M. Development of an Ion Sensitive Field Effect Transistor Based Urea Biosensor with Solid State Reference Systems. Sensors 2010, 10, 6115-6127.
Chang K-M, Chang C-T, Chan K-M. Development of an Ion Sensitive Field Effect Transistor Based Urea Biosensor with Solid State Reference Systems. Sensors. 2010; 10(6):6115-6127.
Chang, Kow-Ming; Chang, Chih-Tien; Chan, Kun-Mou. 2010. "Development of an Ion Sensitive Field Effect Transistor Based Urea Biosensor with Solid State Reference Systems." Sensors 10, no. 6: 6115-6127.