Figure 2.

Liquid droplet experiments on a SH-SAW with Parylene C/ZnO bi-layer waveguide to show the sensor response from gaseous (air above the Parylene 3.5 μm layer) to water to viscous liquid: (a) A 40 μL deionized (DI) water drop deposited on the propagation path compared to gaseous (air) condition. The two null frequencies (location (1) and (3)) exhibit distinct responses to variations in the conditions. (b) A drop of 40 μL dextrose-water mixture (weight ratio DI−water: dextrose powder = 1:0.52) compared to a 40 μL deionized water drop. The loss decreases at location (1) while it increases at location (3). The response at location (2) exhibits subtle changes in response to variations in the conditions.