[paper] Extended gate FET pH Sensor

Shaiful Bakhtiar Hashim, Zurita Zulkifli, Sukreen Hana Herman

Design and Simulation of Electrochemical Equivalent Circuit for Extended gate FET pH Sensor Based on Experimental Value Using LTSPICE XVII

researchsquare.com: November 11th, 2021

DOI:10.21203/rs.3.rs-1031896/v1

  
College of Engineering, UiTM, Selangor (MY)

Abstract: A SPICE model for extended-gate field-effect transistor (EGFET) based pH sensor was developed using standard discrete components. Capacitors and resistors were used to represent the sensing and reference electrodes in the EGFET sensor system and the values of the discrete component were varied to see the output of the transistor. These variations were done to emulate the EGFET sensor output in different pH values. It was found that the experimental transfer and output characteristics of the EGFET were very similar to those from the SPICE simulation. Other than that, the changes of value components in the equivalent circuit did not affect the transfer and output characteristics graph, but the capacitor value produced significant output variation in the simulation. This can be related to the modification on the equivalent circuit was done with additional voltage, VSB (source to bulk) to produce the different VT values at different pH.

Fig: EGFET measurement setup

Acknowledgement: The work is partially supported by KEPU Grant ( 600- RMC/KEPU 5/3 (007/2021)) from Universiti Teknologi MARA