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Article

Temperature-Phase Converter Based on a LC Cell as a Variable Capacitance

Displays and Photonic Applications Group, Department of Electronic Technology, Carlos III University of Madrid, Avenida de la Universidad 30, Leganés E28911, Spain
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Academic Editor: Vittorio M.N. Passaro
Sensors 2015, 15(3), 5594-5608; https://doi.org/10.3390/s150305594
Received: 19 December 2014 / Revised: 25 February 2015 / Accepted: 2 March 2015 / Published: 6 March 2015
(This article belongs to the Section Physical Sensors)
The main characteristic of liquid crystals is that their properties, both electrical and optical, can be modified through a convenient applied signal, for instance a certain voltage. This tunable behavior of liquid crystals is directly related to the orientation of their nanometric components with respect to a director direction. However, the initial alignment is a fabrication-dependent parameter and may be either planar or homeotropic. In addition, the strong dependence of the properties of liquid crystals with the temperature is well known and widely used for several temperature sensors. This dependence is produced by the influence of the temperature on the ordering of the molecules. In this work, we have studied the temperature dependence of the electric properties of a liquid crystal cell, in particular the dielectric permittivity, with the temperature as a function of the initial alignment set during the fabrication process. Starting from experimental measurements, an equivalent circuit model including the temperature dependence has been proposed. We have observed that a good linearity in a wide temperature range is provided at a suitable exciting frequency. Finally, a proper conditioner circuit is proposed as a powerful tool for linear and high sensibility temperature measurement. View Full-Text
Keywords: nematic liquid crystal; impedance analysis; temperature dependence; equivalent circuit; capacitive sensor; simulation nematic liquid crystal; impedance analysis; temperature dependence; equivalent circuit; capacitive sensor; simulation
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MDPI and ACS Style

Torres, J.C.; García-Cámara, B.; Pérez, I.; Urruchi, V.; Sánchez-Pena, J.M. Temperature-Phase Converter Based on a LC Cell as a Variable Capacitance. Sensors 2015, 15, 5594-5608. https://doi.org/10.3390/s150305594

AMA Style

Torres JC, García-Cámara B, Pérez I, Urruchi V, Sánchez-Pena JM. Temperature-Phase Converter Based on a LC Cell as a Variable Capacitance. Sensors. 2015; 15(3):5594-5608. https://doi.org/10.3390/s150305594

Chicago/Turabian Style

Torres, Juan Carlos, Braulio García-Cámara, Isabel Pérez, Virginia Urruchi, and José Manuel Sánchez-Pena. 2015. "Temperature-Phase Converter Based on a LC Cell as a Variable Capacitance" Sensors 15, no. 3: 5594-5608. https://doi.org/10.3390/s150305594

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