Scientists at the University of Pennsylvania, the University of Wisconsin-Madison and IBM Research – Zurich have fabricated an ultrasharp silicon carbide tip possessing such high strength that it is thousands of times more wear-resistant at the nanoscale than previous designs. The new tip, which is 100,000 times smaller than the tip of a pencil, represents an important step towards nanomanufacturing for applications, including bio sensors for healthcare and the environment, says IBM.
The search for hard materials to extend the working life of sharp tools is an age-old problem that started with the first chisels used in stone carving. Eventually iron was discovered and steel tools revolutionized the era. Today, the challenge remains the same, but on a much smaller scale—the need for a nano-sized tip that is both ultrasharp, yet still physically robust, particularly under extreme temperatures and harsh chemical environments.
Dr. Mark Lantz (Manager, Research, IBM Research – Zurich): The dream tip material for thermomechanical nanofabrication should have a high hardness, temperature stability, chemical inertness, and high thermal conductivity.
The new, resistant nano-sized tip wears away at the rate of less than one atom per millimeter of sliding on a substrate of silicon dioxide. This is much lower than the wear rate of conventional silicon tips and its hardness is 100 times greater than that of the previously state-of-the-art silicon oxide-doped diamond-like carbon tips developed by the same collaboration last year.
Consisting primarily of carbon and silicon, the tip is sharpened to a nano-sized apex and integrated on the end of a silicon microcantilever for use in atomic force microscopy. The importance of the development lies not only in its ability to maintain the sharpness of the tip and its resistance to wear, but also in its endurance when sliding against a hard substrate such as silicon dioxide. Because silicon—used in almost all integrated circuit devices—oxidizes in the atmosphere, forming a thin layer of its oxide, this system is among the most relevant for emerging applications in nanolithography and nanomanufacturing applications.
Scientists hope that the new tip can be used to fabricate bio sensors, for example for managing glucose levels in diabetic patients or monitoring pollution levels in water.
[Image courtesy: IBM Research Lab]