Abstract—The Ion-Sensitive Field-Effect Transistor (ISFET)
has traditionally been used to measure hydrogen ion
concentration (pH) of a solution. Its performance depends
mainly on its sensitivity to pH change of the electrolyte in
contact with its gate. This sensitivity is usually calculated by
examining the effect of pH value on the charge and potential
distributions above gate insulator, which is translated into a
shift in the threshold voltage. In this work, we propose a
methodology to extract the sensitivity of ISFET by linking
electrolyte charge and potential equations with a device
simulation tool to calculate the ISFET’s drain current, thus,
taking into account the underlying structure’s physical
properties. Using the proposed methodology, the sensitivity of
ISFET is compared for various pH values and gate-insulator
thicknesses searching for the optimum conditions that give the
highest sensitivity.
Index Terms—ISFET, pH-sensor, biosensors, device
simulation.
Tarek M. Abdolkader and A. G. Alahdal are with the Electrical
Engineering Department, Faculty of Engineering, Umm Al-Qura University,
Saudi Arabia, on leave from Benha University, Benha, Egypt (e-mail:
tmhasan@ uqu.edu.sa, agahdal@uqu.edu.sa).
A. Shaker and W. Fikry are with the Engineering Physics Department,
Ain Shams University, Egypt (email: ashaker2k@yahoo.com,
waelfikry@yahoo.com).
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Cite: Tarek M. Abdolkader, Abdurrahman G. Alahdal, Ahmed Shaker, and Wael Fikry, "ISFET pH-Sensor Sensitivity Extraction Using Conventional MOSFET Simulation Tools," International Journal of Chemical Engineering and Applications vol. 6, no. 5, pp. 346-351, 2015.
