When it comes to creating surfaces, it's a simple task to either make ones that are smooth or ones that are bumpy. But now researchers at MIT have created one that can be both. The 3D-printed surface they have created can be either smooth, bumpy, ridged, or channeled and can dynamically change texture through the application of pressure.
Mutable surface textures are important in controlling unwanted animals growing on ship hulls, channeling microscale amounts of fluids, creating camouflage, and optics. And importantly, the surfaces created by the MIT team were produced using a 3D printer, potentially allowing easy dissemination and creativity with the technique.
Embedded within a soft matrix of flexible printed material are regions of a harder polymer. When the final structure is compressed, the softer material yields more than the hard particles, mutating the surface texture. By altering the size, shape, and distribution of the harder particles, the researchers were able to obtain ridges, bumps, creases, apexes, and channels in different mathematically-derived computer simulations.
The technique also allows for creating surfaces that are smooth in one direction but generate friction in the opposite direction, much like trying to pet a cat backwards. Other printed tests created a smooth surface that easily let liquid flow, but developed channels to control direction and speed.
Because this method relies primarily on the geometry of the materials, the researchers say it can be scaled to almost any size. A similar approach could be made using materials that are sensitive to voltage, temperature or humidity to create a secondary texture based on the delta between two or more materials.
This research was originally published in Advanced Functional Materials.