Capacitive Transduction for Liquid Crystal-Based Sensors, Part I: Ordered System

• Published in: IEEE sensors journal Vol. 7; no. 12; pp. 1617 - 1624
• Main Authors: Abu-Abed, A., Lindquist, R.G., Woo-Hyuck Choi
• Format: Journal Article
• Language: English
• Published: New York IEEE 01-12-2007; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Anisotropic magnetoresistance; Biological materials; Biosensors; capacitive sensing; Capacitive sensors; Chemical and biological sensors; Chemical sensors; Crystalline materials; Electrodes; Fingers; liquid crystal (LC); Liquid crystals; Liquids; Mathematical analysis; Optical distortion; Orientation; Sensor systems; Sensors; Tracking
• ISSN: 1530-437X; 1558-1748
• DOI: 10.1109/JSEN.2007.908504

In this paper, the theory for tracking the average molecular orientation of a liquid crystal (LC) material via capacitive sensing of anisotropic media is presented. The candidate LC sensor structure utilizes interdigital electrodes. Two capacitive measurements in orthogonal direction can track the director axis of nematic LC material in a homogenous ordered LC film. The sensitivity for the sensor at different alignments is studied. The candidate sensors have been fabricated and experimentally verified. Both experimental and calculated values for capacitances of selected interdigital fingers sensor structures are presented.