Self-powered microfluidic sheets move like a flying carpet

Scientists from the University of Pittsburgh Swanson School of Engineering have designed an interesting two-dimensional, shape-changing sheet that can move autonomously in a reactant-filled fluid. The sheet gets its inspiration from a magic carpet that flies people around in films like "Aladdin." The team says that it had long been a challenge in chemistry to design a non-living object that moves on its own in the environment and alter the object's shape.

The system that the scientists have created uses a chemical reaction to activate the fluid motion that can transport the flexible object and "sculpt" the shape of the object autonomously. To create the object, the team applied a coating of catalysts on a flexible sheet roughly the width of a human hair. The reactants added to the surrounding fluid initiate the carpet's motion and changes its form.

Dr. Anna C Balazs says that this is the first time to their knowledge that this sort of catalytic chemical reactions has been applied to 2-D sheets to generate flows that make the sheets mobile. The team was able to place different catalysts on specific areas of the sheet and control the amount and type of reactants in the fluid to create a useful cascade of catalytic reactions that break down an associated chemical that becomes the reactant for the next set of catalytic reactions.

Experiments showed that different catalyst placement on different parts of the sheet could create specific motions. One of the experiments had the team place a catalyst on just the body of the sheet, not the head and tail. This created a creeping movement said to be similar to an inchworm.

The team also found that when obstacles were placed in front of the coated sheet, it was able to tumble over them and continue moving. The group says the next task is to explore microfabrication using the interaction and self-organization of multiple sheets to make them into specific architectures needed for particular functions.