Improving the stability of surface acoustic wave (SAW) chemical sensor coatings using photopolymerization

Submicron particles of a diethyl ester of p-phenylenediacrylic acid (EPA) were produced by the technique known as rapid expansion of supercritical solutions (RESS) and were deposited onto surface acoustic wave (SAW) resonators. The EPA particles were polymerized in the solid-state directly on the surface of the SAW devices in order to stabilize the mechanical properties of the sensor coatings. The sensor affinity to particular vapors was enhanced by performing the polymerization step in the presence of organic template vapors. The resulting SAW sensors exhibited high quality factors (Q0) and we have demonstrated the sensor stability for periods up to 3.8 years.