Utilization of DLP 3D printing towards Superhydrophobic Surfaces

The fabrication of sub-100 µm features with re-entrant textures is crucial for the development of the superhydrophobic surfaces, which have potential applications in different fields such as self-cleaning coatings, anti-fouling, stain-free clothing, separation of liquids and other additional uses. However, fabricating such distinctly separated and dimensionally uniform features with sub-100 µm inter-feature edge-to-edge distance is a challenge. Using Digital Light Processing (DLP) Additive Manufacturing technology, this study leverages the varied energy profile afforded by grayscale 2D projection images to achieve uniform illumination for curing at the resin surface and controlling the cumulative light energy profile. Grayscale masks of the intended design are obtained using a custom MATLAB program and locally measured light intensity. Next, the sliced 2D images are processed using the mask image and fed into the DLP system. Pixelwise grayscale values at the feature boundaries were adjusted to control the lateral curing width and obtain the dimensionally accurate features. The surface of the printed part was post-functionalized with a surface coating and tested for superhydrophobicity by observing the behavior of water droplets on the printed surface. The fabricated surfaces achieved superhydrophobicity readily with post-print functionalization. This study demonstrates the promising approach to the development of advanced surfaces with re-entrant features of different shapes to achieve superhydrophobicity and highlights the potential of the DLP technology for fabricating complex microstructures and more advanced surfaces with precise control.