Lotus Leaf-Inspired Low-Adhesion Surface for a Droplet-Based Electricity Generator

Droplet-based electricity generators (DEGs) are usually characterised under dry conditions, although retained water can alter their electrical boundary. We compared blank, bottom-wetted, top-wetted, wetted-and-dried, and partially immersed states using 40 mm × 40 mm FEP/ITO devices. Four separately assembled devices per condition were tested on a separate apparatus, with 100 droplet events per device. The device averages were analysed by Welch's ANOVA and Holm-adjusted contrasts. Bottom wetting changed the average peak voltage by -0.30% relative to the blank (adjusted p = 0.960), whereas top wetting reduced it by 56.21% (adjusted p = 2.62 × 10^-9). The dried-state average was within 0.38% of the blank (adjusted p = 0.960), indicating electrical recovery under the stated protocol without establishing equivalence or complete drying. Immersing 10%, 30%, and 50% of the device length reduced the average by 19.31%, 34.59%, and 47.73%, respectively. The common-state averages agreed within 1.49% with an earlier apparatus series. A process-matched MWCNT:FEP surface reached an apparent contact angle of 151° and a 6° sliding angle while retaining 87.3% of the FEP-only average. These results identify the exposed top surface, rather than the bottom-interface water, as the principal wetting-state sensitivity under the tested conditions and support a lotus-inspired low-adhesion design target.