A completely monolithic high-Q oscillator, fabricated via a combined CMOS plus surface micromachining technology, is described, for which the oscillation frequency is controlled by a polysilicon micromechanical resonator to achieve stability and phase noise performance comparable to those of quartz crystal oscillators. It is shown that the closed-loop, steady-state oscillation amplitude of this...

The Casimir force between uncharged metallic surfaces originates from quantum-mechanical zero-point fluctuations of the electromagnetic field. We demonstrate that this quantum electrodynamical effect has a profound influence on the oscillatory behavior of microstructures when surfaces are in close proximity (< or =100 nm). Frequency shifts, hysteretic behavior, and bistability caused by the Cas...

In the present work, damage propagation in thermoplastic composite laminates subjected to quasi-static tensile loading was numerically simulated using different models. The simulation performed commercial finite element suite LS-Dyna, where various material models were evaluated based on their ability simulate behavior. More specifically, Tsai-Wu failure criteria (MAT_055), progressive modeling...

An experimental method, employing a scanning tunneling microscope ~STM! as an actuator and a scanning electron microscope ~SEM! as a motion detector, was developed to study microelectromechanical systems ~MEMS! and has been applied to study microfabricated cantilever beams. Vibrations actuated by an ac voltage applied to the piezodrive are transferred to the sample by the STM tip, which also pr...

A technique in which a micromechanical resonator is operated at large amplitudes while in situ localized annealed to temperatures exceeding 880 o C is shown to be an effective method for both removal of surface contaminants and for possible " redistribution " of the structural material towards substantially higher quality factor Q and greatly enhanced drift stability. The technique not only pro...

Integrin-mediated mechanotransduction in vascular smooth muscle cells (VSMCs) plays an important role in the physiological control of tissue blood flow and vascular resistance. To test whether force applied to specific extracellular matrix (ECM)-integrin interactions could induce myogenic-like mechanical activity at focal adhesion sites, we used atomic force microscopy (AFM) to apply controlled...

In this paper, interphases in unidirectional fiber-reinforced composites under transverse loading are modeled by an advanced boundary element method based on the elasticity theory. The interphases are regarded as elastic layers between the fiber and matrix, as opposed to the spring-like models in the boundary element method literature. Both cylinder and square unit cell models of the fiber-inte...