Fig. 4 Single-particle contact angle measurements. Single-particle contact angle measurements. (A) Schematic diagram of single-nanoparticle contact angle measurement process using a gel trapping technique. SEM images of an SP (B) and an M-SP (C) embedded in PDMS for contact angle measurements (SP, ~78.4° ± 4.9°; M-SP, ~99.0° ± 3.6°). Scale bars, 200 nm. Ming Xiao et al. Sci Adv 2019;5:eaax1254 Copyright © 2019 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).