Figure 6
Comparison of stability to liquid pressure between cylindrical and line-shaped microstructures. (a) and (b) Shows the SEM images of the cylindrical (f = 0.03) and line-shaped (f = 0.09) pPFDA-coated VA-CNT microstructures, respectively. (c) A schematic showing a typical droplet base (droplet curvature is not shown) and the different force zones (high, medium, and low are relative, just shown for better understanding) with the cylindrical and line-shaped microstructures. (d) Plots showing the variation in the contact angle, θ (left panel), Laplace pressure, PL (middle panel) and FPL (right panel) during the evaporation of a 4 μL water droplet on the cylindrical (f = 0.03) and line-shaped microstructures (f = 0.09). Though the trends of the Laplace pressure (PL) are the same, the FPL values with cylindrical microstructures are higher than the line-shaped microstructures as the cylindrical microstructures have smaller solid-liquid contact length for a given center-to-center spacing (S). Alternatively, line-shaped microstructures offer enhanced solid-liquid contact length for a given center-to-center spacing (S) and hence have lower FPL values and are more stable to liquid pressure than the cylindrical microstructures. The scale bar in (a,b) is 50 μm.
