Artificial, bonelike material developed.

• Position: Medical Devices

An approach for better integrating medical devices with biological systems has been developed at the University of Chicago (III.). Led by Bozhi Tian, assistant professor in chemistry, researchers have developed the first skeleton-like silicon spicules ever prepared via chemical processes.

One striking advance achieved by the team was the demonstration, by strictly chemical means, of three-dimensional lithography. Existing lithographic techniques create features over flat surfaces. The laboratory system mimics the natural reaction-diffusion process that leads to symmetry-breaking forms in nature: the grooved and notched form of a bee stinger, for example.

Tian's team developed a pressure modulation synthesis to promote the growth of silicon nanowires and to induce gold-based patterns in the silicon. Gold acts as silicon's growth catalyst. By repeatedly increasing and decreasing the pressure on their samples, the researchers were able to control the gold's precipitation and diffusion along the silicon's faceted surfaces. "The idea of utilizing deposition-diffusion cycles can be applied to synthesizing more complex 3D semiconductors," notes co-lead author Yuanwen Jiang, a fellow in chemistry.

In another advance, Tian and his associates developed a novel chemical method that instead depends upon the uncanny ability of gold atoms to trap silicon-carrying electrons to...