Roberto Ballarini

Department of Civil Engineering

University of Minnesota





Microelectromechanical systems (MEMS) devices have been developed to measure the strength, fracture toughness, and subcritical crack growth rates of polycrystalline silicon and silicon carbide at the micron scale. These devices, fabricated using standard MEMS processing techniques, have characteristic dimensions comparable to typical MEMS components (notches, cracks and uncracked ligaments of several microns). The first device involves a specimen that is fully integrated with simultaneously fabricated electrostatic actuators that are capable of providing sufficient force to ensure failure under monotonic or cyclic loading. The second is a passive device that is loaded, upon release, by the residual stresses that develop during processing. For both devices the entire experiment takes place on-chip, eliminating the difficulties associated with attaching the specimen to an external loading source.

The first part of this talk presents experimental results obtained on silicon and silicon carbide. The second part of the talk describes the use of similar on-chip (MEMS) devices to test the mechanical properties of nanoscale natural and synthetic structures, including collagen fibrils and carbon nanotubes.


   MEMS Fracture Device                         Tension Test on Collagen Fibril