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BioFETs. ISFET integrated catheter tip. Measure in vivo physiological parameters Example: Cordis catheter (Al 2 O 3 ISFET integrated) Studies using this device showed that blood pH changes periodically with lung ventilation Biocompatibility issues prevented widespread use. BioFETs.
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ISFET integrated catheter tip • Measure in vivo physiological parameters • Example: Cordis catheter (Al2O3 ISFET integrated) • Studies using this device showed that blood pH changes periodically with lung ventilation • Biocompatibility issues prevented widespread use
EnFET – Enzyme FET Enzyme is immobilized on the gate oxide of the ISFET Enzymes: Urease, glucose penicillinase, etc.
CellFET • Integrated cell culture monitoring system • Temp. measurement: diode • Conductivity: interdigitated array electrode • O2: amperometric • pH: ISFET • All on single Si chip • Useful for studying effect of drugs on cell culture
Membrane modified FET (MEMFET) • If the gate oxide of the ISFET is covered with an ion-selective membrane, the device is known as a MEMFET. • K+ sensitive FET (1st MEMFET) • Ca2+ sensitive MEMFET (with ion exchanger in polymeric membrane) or deposition of AgBr membranes (Ag+ or Br- sensors) • Issue: Due to poor adhesion of the membrane to the gate oxide it can peel off easily and its electroactive components may leach out.