A comparison of three methods of depositing thin films on fiber mat. Top image: The uncoated mat, with its complex fiber structure clearly visible. Second image down: A liquid-based process produces irregular coverage of the fibers. Third image: An evaporation process creates a coating that covers over the fibers. Fourth image: MIT’s oxidative chemical vapor deposition (oCVD) process yields a thin film that is “conformal,” with the individual fibers still visible. Only the oCVD film will not change the structure, flexibility, or other characteristics of the underlying material. Photo: Gleason Lab
The remarkable features of the vapor-printed anodes—including their flexibility and robustness—can be traced to details of the oCVD process. Most notably, oCVD produces an unusually tight adherence between the deposited material and the substrate. The images show the results of using three methods of depositing thin films on fiber mat. The first image shows the uncoated mat, with its complex fiber structure. The coating in the second image, created using a liquid-based process, is irregular, with blobs in some areas and no coverage in others. The one in the third image, made with an evaporation process, covers the surface such that individual fibers are no longer distinguishable. The final image shows the outcome using oCVD: a thin film that conforms to the surface so that the individual fibers of the mat are still clearly visible.