DESIGN AND IMPLEMENTATION OF FOUR ELECTRODE BASED IMPEDIMETRIC SENSORS

Abstract

The continuous development of cell based microelectronic sensing devices has been a significant milestone in the drug discovery and in depth bio-analytical researches on living cell behavior and its physiology. Along with time, conventional cell based sensors have faced some limitations which paved the way to shift towards Electric Cell Substrate Impedance Sensor which ensures non invasive, real time and label free impedance sensing of the living cells as well as lower cost and higher accuracy. The low impedance of the sensing device plays a vital role in measuring the accurate impedance of living cells. With that aim, an optimized, non invasive four electrode based Electric Cell-substrate Impedance Sensing (ECIS) device has been designed, fabricated and then characterized in this work. The ECIS device is designed with gold electrodes and the impedance of the designed device has been simulated by varying different parameters and was compared and verified with equivalent electrical circuit parameters. The designed device was further fabricated with gold on a glass substrate and was characterized with biocompatible Phosphate Buffer Solution (PBS) where the obtained design parameters from the simulations were applied. The measured impedance data were compared with equivalent circuit models with an electrochemical impedance spectroscopy analysis software to realize the feasibility and error percentage of the device. The output impedance data of the fabricated device fitted well with the simulated data which was later used for the realization of the equivalent circuit model of this electrochemical system as well as the mathematical equations between the impedance, phase angle and the area of electrode for the device which can be used for further researches of cell impedances in future works.