MIT researchers have used additive manufacturing to develop a new method of manufacturing soft materials. By combining hard materials and soft composites into a single object, researchers have created a material that can change its surface topology when subjected to stress.

“Depending on the arrangement of the particles, using the same amount of compression, you can get different surface topographies, including ridges and bumps, along the surface,” said MIT graduate student Mark Guttag, who, with student Mary Boyce, helped develop the method.

Another method for creating reversible surface topographies is surface wrinkling, which attaches a stiff material to the surface of soft substrate. While wrinkled surfaces have many applications, they are more difficult to use. Guttag and Boyce’s method differs from surface wrinkling’s traditional design. Instead of attaching a stiff material to the surface of the soft material, it’s attached beneath the surface of the particle-enhanced soft composites (PESCs). According to Guttag and Boyce, the level of topographic change depends on the size, shape, spacing and the arrangement of the particles.

A complex version of the material can be used to change the aerodynamic resistance of an object, or its reflectivity. Potential applications of the material include camouflage, as well as fabricated surfaces that attract or repel water, reduce drag and possibly decrease organism buildup on ships.

“This is the first-of-its-kind work to create materials with reconfigurable surface texture,” commented Yonggang Huang, a professor at Northwestern University who was not involved in this work. “The potential practical impact of this work is huge. It can be used in many applications that benefit from the change of surface, such as in optics and tribology [the science of interacting surfaces in motion].”

For more information, read Guttag and Boyce’s paper, Locally and Dynamically Controllable Surface Topography Through the Use of Particle-Enhanced Soft Composites, at the Wiley Online Library.