Although it looks small and unassuming, the tiny origami crane sitting in a sample dish in University of Illinois professor Jennifer Lewis’ lab heralds a new method for creating complex three-dimensional structures for biocompatible devices, microscaffolding and other microsystems. The penny-sized titanium bird began as a printed sheet of titanium hydride ink.
The team will publish their novel technique in the April 14 online edition of the journal Advanced Materials.
Small, intricate shapes made of metals, ceramics or polymers have a variety of applications, from biomedical devices to electronics to rapid prototyping. One method of fabricating such structures is by direct-write assembly, which the Lewis group helped pioneer. In this approach, a large printer deposits inks containing metallic, ceramic or plastic particles to assemble a structure layer by layer. Then, the structure is annealed at a high temperature to evaporate the liquid in the ink and bond the particles, leaving a solid object.
However, as more layers are added, the lower layers tend to sag or collapse under their own weight – a problem postdoctoral researcher Bok Yeop Ahn encountered while trying to manufacture titanium scaffolds for tissue engineering. He decided to try a different approach: Print a flat sheet, then roll it up into a spiral – or even fold it into an assortment of shapes.
Folding the printed sheets is not as easy as it would first seem.
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