Development of an Ion Sensitive Field Effect Transistor Based Urea Biosensor with Solid State Reference Systems

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/Nafion™ 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

ISFET sensor coupled with CMOS read-out circuit microsystem

We report on the development of a prototype microsystem for measurement of pH, i.e. H+ ions concentration, of acqueous electrolytic solution with a resolution higher than 1/20 of pH. The microsystem is composed of an ISFET sensor coupled with a CMOS read-out channel capable to provide a low-impedance analog output and protection against electrostatic discharges. The silicon integrated ISFET sensor chip and the CMOS read-out chip have been fabricated, packaged and successfully tested at IRST-Microsystem Division of Trento (Italy) by using the internal microfabrication facilit

CMOS interfaces for silicon integrated microsensors

Dottorato di ricerca in dispositivi elettronici. 12. ciclo. Revisore Giovanni SonciniConsiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7, Rome; Biblioteca Nazionale Centrale - Piazza Cavalleggeri, 1, Florence / CNR - Consiglio Nazionale delle RichercheSIGLEITItal

Compact CMOS implementation of a low-power, current-mode programmable cellular neural network

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A Versatile Photodiode SPICE Model for Optical Microsystem Simulation

We report on the definition and the implementation in ANACAD Eldo simulator of a photodiode circuit macro-model to be used in the design of optical smart sensors such as position sensing detectors (PSD`s) and digital cameras. The optical power waveform as well as its spectrum can be easily defined by the user, allowing for a high flexibility of the model. The effectiveness of the proposed macro-model is highlighted by comparing Eldo simulation results with both numerical device simulation results and experimental dat

A new current mode programmable cellular neural network

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