Optimized SAW chemical sensor with microfluidic packaging

Surface acoustic wave (SAW) devices are used as sensing elements in the best performing portable chemical detectors. The SAW device, with a selectively absorbing chemical coating, serves as a mass sensor which preferentially responds to various chemical exposures. To obtain the highest performance, a number of criteria must be optimized, including SAW microwave insertion loss, impedance matching, electrode design configuration, RF shielding, chemically absorbent coating area, electronic measurement approach, and microfluidic packaging. A properly optimized system can be sensitive to chemical exposures the parts-per-trillion range. We report on a design optimization approach consisting of multiple comparison experiments made with competing designs.