Development of chemical field effect transistors for the detection of urea

Low cost, disposable, chemical field effect transistor (ChemFET) microsensors including a SiO2/Si3N4 pH-sensitive gate, a ChemFET/ReFET structure and a titanium/gold pseudo-electrode have been fabricated using a standard P-well silicon technology. The fabrication process is described and sensor properties and performances are demonstrated through pH measurements. The pH-ChemFET is adapted to biochemical applications owing to photosensitive polyvinyl alcohol (PVA) layers patterned by standard photolithography techniques. Application is performed through the development of urease-based enzymatic field effect transistor (U-EnFET) for the detection of urea. The microsensor will be used for blood analysis and more precisely for hemodialysis. (C) 2003 Elsevier B.V. All rights reserved.