Analysis of liquid-phase chemical detection using guided shear horizontal-surface acoustic wave sensors.
Direct chemical sensing in liquid environments using polymer-guided shear horizontal surface acoustic wave sensor platforms on 36 degrees rotated Y-cut LiTaO3 is investigated. Design considerations for optimizing these devices for liquid-phase detection are systematically explored. Two different sensor geometries are experimentally and theoretically analyzed. Dual delay line devices are used with a reference line coated with poly (methyl methacrylate) (PMMA) and a sensing line coated with a chemically sensitive polymer, which acts as both a guiding layer and a sensing layer or with a PMMA waveguide and a chemically sensitive polymer. Results show the three-layer model provides higher sensitivity than the four-layer model. Contributions from mass loading and coating viscoelasticity changes to the sensor response are evaluated, taking into account the added mass, swelling, and plasticization. Chemically sensitive polymers are investigated in the detection of low concentrations (1-60 ppm) of toluene, ethylbenzene, and xylenes in water. A low-ppb level detection limit is estimated from the present experimental measurements. Sensor properties are investigated by varying the sensor geometries, coating thickness combinations, coating properties, and curing temperature for operation in liquid environments. Partition coefficients for polymer-aqueous analyte pairs are used to explain the observed trend in sensitivity for the polymers PMMA, poly(isobutylene), poly(epichlorohydrin), and poly(ethyl acrylate) used in this work.
Li
Zhonghui
Z
Microsensor Research Laboratory and Department of Electrical and Computer Engineering, Marquette University, P.O. Box 1881, Milwaukee, Wisconsin 53201-1881, USA.
Jones
Yolanda
Y
Hossenlopp
Jeanne
J
Cernosek
Richard
R
Josse
Fabien
F
D000180:Acrylic Resins / Q000032:analysis*; D002623:Chemistry Techniques, Analytical / Q000295:instrumentation* / Q000379:methods; D004811:Epichlorohydrin / Q000031:analogs & derivatives* / Q000032:analysis*; D011090:Polyenes / Q000032:analysis*; D011108:Polymers / Q000032:analysis*; D019904:Polymethyl Methacrylate / Q000032:analysis*; D012680:Sensitivity and Specificity
D000180:Acrylic Resins; D011090:Polyenes; D011108:Polymers; C478961:poly(ethylacrylate); D004811:Epichlorohydrin; C008967:polyisobutylene; D019904:Polymethyl Methacrylate