Sophisticated shape-shifters for soft robots, biomedical applications

Scientists have created a liquid crystal elastomer that can be molded into shapes that shift from one to another when heated. The material is intended for biomedical and robotics applications.

Rice University scientists have created a rubbery, shape-shifting material that morphs from one sophisticated form to another on demand.

The shapes programmed into a polymer appear in ambient conditions and melt away when heat is applied. The process also works in reverse.

The smooth operation belies a battle at the nanoscale, where liquid crystals and the elastomer in which they're embedded fight for control. When cool, the shape programmed into the liquid crystals dominates, but when heated, the crystals relax within the rubber band-like elastomer, like ice melting into water.

In most of the samples the team has made so far, including a face, a Rice logo, a Lego block and a rose, the material takes on its complex shape at room temperature, but when heated to a transition temperature of about 80 degrees Celsius (176 degrees Fahrenheit), it collapses into a flat sheet. When the heat is removed, the shapes pop back up within a couple of minutes.

As fanciful as this seems, the material shows promise for soft robots that mimic organisms and in biomedical applications that require materials that take pre-programmed shapes at body temperature.

The liquid crystal state is easiest to program. Once the material is given shape in a mold, five minutes of curing under ultraviolet light sets the crystalline order. The team also made samples that switch between two shapes.


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