Title :
Sensitivity Enhancement of Quartz Crystal Capacitive Sensor Using Series Inductive Reactance
Author :
Xing Ding ; Xiangdong Chen ; Xiaoyu Li ; Zuquan Wu ; Yao Yao
Author_Institution :
Sch. of Inf. Sci. & Technol., Southwest Jiaotong Univ., Chengdu, China
Abstract :
In this paper, resonant frequency expression for equivalent circuit of quartz crystal capacitive sensor in series with a tuning inductor was derived. The expression indicates that cascading inductance can significantly increase the load capacitance sensitivity. Experiments using nominal capacitors in series with a calculated inductance validated the theoretical derivation and showed that the frequency pulling sensitivity versus capacitance variations was considerably improved in different levels depending on the quartz crystal fundamental frequency. A quartz crystal capacitive proximity sensor with a calculated inductance was also investigated. Compared with conventional quartz crystal capacitive proximity sensor, the displacement sensitivity of the new sensor with an inductor can be improved two times or more. The new circuit can be used to develop high-sensitivity capacitive sensor.
Keywords :
capacitance measurement; capacitive sensors; capacitors; equivalent circuits; inductance measurement; inductors; quartz; capacitor; equivalent circuit; frequency pulling sensitivity; load capacitance sensitivity; quartz crystal capacitive proximity sensor; quartz crystal fundamental frequency; resonant frequency expression; sensitivity enhancement; series inductive reactance; tuning inductor; Capacitance; Capacitive sensors; Crystals; Oscillators; Resonant frequency; Sensitivity; Quartz crystal; capacitive proximity sensor; inductive reactance; sensitivity enhancement; series resonance frequency;
Journal_Title :
Sensors Journal, IEEE
DOI :
10.1109/JSEN.2014.2308308