Title :
In-liquid sensing of chemical compounds by QCM sensors coupled with high-accuracy ACC oscillator
Author :
Ferrari, Marco ; Ferrari, Vittorio ; Marioli, Daniele ; Taroni, Andrea ; Suman, Michele ; Dalcanale, Enrico
Author_Institution :
Dept. of Electron. for Autom., Univ. of Brescia
fDate :
6/1/2006 12:00:00 AM
Abstract :
A novel oscillator circuit with automatic capacitance compensation (ACC) capability has been coupled with quartz-crystal-microbalance (QCM) sensors coated with quinoxaline- and pyrazine-bridged cavitands to detect aromatic and chlorinated compounds in water. With double-side immersed 10-MHz crystals coated with the quinoxaline cavitand, the detection of toluene in deionized water was possible down to concentrations of a few parts per million. The ACC oscillator advantageously provides the simultaneous measurement of the sensor resonant frequency, damping, and value of the compensated parallel capacitance. This enabled observing that the analyte sorption in the cavitand coating not only brings about a mass uptake but also an increase of losses and, apparently, a rise in the coating average permittivity
Keywords :
capacitance; chemical sensors; coatings; damping; frequency measurement; microbalances; oscillators; 10 MHz; analyte sorption; aromatic compounds; automatic capacitance compensation; cavitand coating; chemical compounds; chlorinated compounds; coating average permittivity; deionized water; in-liquid chemical sensing; oscillator circuit; pyrazine-bridged cavitands; quartz crystal microbalance sensors; quinoxaline cavitand; resonant frequency measurement; toluene detection; Capacitance measurement; Capacitive sensors; Chemical compounds; Chemical sensors; Coatings; Coupling circuits; Crystals; Frequency measurement; Oscillators; Permittivity measurement; Capacitance compensation; cavitands; in-liquid chemical sensing; oscillator circuit; quartz-crystal-microbalance (QCM);
Journal_Title :
Instrumentation and Measurement, IEEE Transactions on
DOI :
10.1109/TIM.2006.873792
