The Effects of Excitation Signal on the Resolution of the Liquid Crystal Capacitive Chemical and Biological Sensors


1 ECE Department, Shahid Beheshti University

2 ECE Department, University of Alabama in Huntsville

3 ECE Department, The University of Alabama in Huntsville


In this paper excitation characteristics of the Liquid Crystal (LC) capacitive chemical and biological sensor are examined and the optimum frequency and voltage range for the sensor interface are introduced. Interdigitated capacitor has been used for the sensor capacitance measurement and two different molecular orientations, homeotropic and homogenous, have been considered. The LC sensor capacitance has been measured for different frequencies from 20Hz to 2MHz and voltages from 0/5V to 20V. In both cases, the effects of excitation on the capacitance value and the accuracy of the measurement are investigated. Simulation and experimental results support the proposed range of measurement.