Yu, YanhaoBrandt, SorenNicolas, Natalie J.Aizenberg, Joanna2020-01-152019-12-06Yu, Yanhao, Soeren Brandt, Natalie J. Nicolas, and Janna Aizenberg. "Colorimetric Ethanol Indicator Based on Instantaneous, Localized Wetting of a Photonic Crystal." ACS Applied Material and Interfaces 12, no. 1 (Jan 2020): 1924-1929. 10.1021/acsami.9b198361944-82441944-8252http://nrs.harvard.edu/urn-3:HUL.InstRepos:42165869Easy-to-use sensors for ethanol solutions have broad applications ranging from monitoring alcohol quality to combating underage drinking. Although there are a number of electronic and colorimetric sensors available for determining alcohol concentration, there is currently no device that can concurrently provide a prompt, well-defined, quickly recoverable readout and remain readily affordable. Here, we developed a field-ready, colorimetric indicator that provides a fast, clear identification of ethanol-water mixtures between 0 and 40% based on the discoloration of a wetted photonic crystal. We cooperatively exploit the iridescence and the geometrical gating in silica inverse opal films (IOFs), together with a fine-tuned surface chemistry gradient, to distinguish ethanol concentrations by their wettability patterns in the different segments of the IOFs. The resultant all-in-one colorimetric sensor delivers a striking and instantaneous optical response at an ethanol concentration as low as 5%. We further improve the ease of use by seamlessly integrating this colorimetric platform with drinking glassware (a glass stirrer and a vial). This research provides an optimal means for colorimetric ethanol detection and is a step toward the immersible sensing of diverse molecules (e.g., biomarkers) in aqueous solutions without expensive laboratory tests.en-USGeneral Materials ScienceJournal Article2020-01-1510.1021/acsami.9b19836