Scientists at Sandia National Laboratories, Albuquerque, N.M., have created what are believed to be the world's first diamond micromachines. These devices are etched from a surface of amorphous diamond, the hardest material in the world after crystalline diamond, and they are compatible with current silicon chip and surface micromachine manufacturing techniques.
The researchers are investigating amorphous diamonds because of their superior wear-resistant qualities and resistance to stiction—a combination of stickiness and friction. The diamonds also have potential as a biocompatible material that could be used inside the human body for medical purposes without generating an allergic reaction.
Sandia has constructed a diamond comb drive with tiny interspaced teeth that move forward and back as an electrical current reverses constantly between positive and negative (see the figure). This is the first demonstration of a micromotion drive using amorphous diamond.
"The point," says researcher John Sullivan, "is to create a layering technology useful in increasing the life span and performance of micromachines." Also, Tom Friedmann says, "Micromachines, for their marvelously tiny size, are still machines. They're subject to wear, even if it's only at the micro level. Diamond is more wear-resistant than polysilicon."
Researchers expect amorphous diamond to last 10,000 times longer than polysilicon in wear applications. According to Sandia, the material is chemically benign and compatible with silicon. It could function as another station in the line in the creation of a basically silicon micromachine, but with a diamond layer for additional strength and durability. Someday, it may even be used as a complete replacement for polysilicon.
For more information, go to www.sandia.gov/media/NewsRel/NR2000/diamond.htm.