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Proceedings Paper

Ion-sensitive field effect transistors for pH and potassium ion concentration sensing: towards detection of myocardial ischemia
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Paper Abstract

Ion Sensitive Field Effect Transistors (ISFETs) for sensing change in ionic concentration in biological systems can be used for detecting critical conditions like Myocardial Ischemia. Having the ability to yield steady signal characteristics can be used to observe the ionic concentration gradients which mark the onset of ischemia. Two ionic concentrations, pH and [K+], have been considered as the indicator for Myocardial Ischemia in this study. The ISFETs in this study have an organic semi-conductor film as the electronically active component. Poly-3 hexylthiophene was chosen for its compatibility to the solution processing, which is a simple and economical method of thin film fabrication. The gate electrode, which regulates the current in the active layer, has been employed as the sensor element. The devices under study here were fabricated on a flexible substrate PEN. The pH sensor was designed with the Tantalum Oxide gate dielectric as the ion selective component. The charge accumulated on the surface of the metal oxide acts as the source of the effecter electric field. The device was tested for pH values between 6.5 and 7.5, which comprises the variation observed during ischemic attack. The potassium ion sensor has got a floating gate electrode which is functionalized to be selective to potassium ion. The device was tested for potassium ion concentration between 5 and 25 mM, which constitutes the variation in extra cellular potassium ion concentration during ischemic attack. The device incorporated a monolayer of Valinomycin, a potassium specific ionophore, on top of the gate electrode.

Paper Details

Date Published: 31 March 2008
PDF: 6 pages
Proc. SPIE 6931, Nanosensors and Microsensors for Bio-Systems 2008, 69310I (31 March 2008); doi: 10.1117/12.776205
Show Author Affiliations
Pratyush Rai, Univ. of Arkansas (United States)
Soyoun Jung, Univ. of Arkansas (United States)
Taeksoo Ji, Univ. of Arkansas (United States)
Vijay K. Varadan, Univ. of Arkansas (United States)

Published in SPIE Proceedings Vol. 6931:
Nanosensors and Microsensors for Bio-Systems 2008
Vijay K. Varadan, Editor(s)

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