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

Pratyush Rai; Soyoun Jung; Taeksoo Ji; Vijay K. Varadan

doi:10.1117/12.776205

31 March 2008 Ion-sensitive field effect transistors for pH and potassium ion concentration sensing: towards detection of myocardial ischemia

Pratyush Rai, Soyoun Jung, Taeksoo Ji, Vijay K. Varadan

Author Affiliations +

Proceedings Volume 6931, Nanosensors and Microsensors for Bio-Systems 2008; 69310I (2008) https://doi.org/10.1117/12.776205
Event: SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring, 2008, San Diego, California, United States

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.

Citation Download Citation

Pratyush Rai, Soyoun Jung, Taeksoo Ji, and Vijay K. Varadan "Ion-sensitive field effect transistors for pH and potassium ion concentration sensing: towards detection of myocardial ischemia", Proc. SPIE 6931, Nanosensors and Microsensors for Bio-Systems 2008, 69310I (31 March 2008); https://doi.org/10.1117/12.776205

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