Number 170 (Story #2), March 28, 1994 by Phillip F. Schewe and Ben Stein BUILDING WHOLE INSTRUMENTS ON A CHIP with integrated-circuit technology is a major goal in the field of microelectromechanical systems (MEMS). At a session devoted to this subject at the APS meeting, Susanne Arney of AT&T Bell Labs described, for example, efforts to make tiny tunneling probe microscopes with the same lithographic, etching, undercutting (etc.) steps used in micro-circuit fabrication. Jason Yao of Rockwell described micro-resonators consisting of micron-sized arms of silicon which, once excited by voltage pulses, oscillate consistently at MHz frequencies. The purity of the tone of this "tuning fork" is such that the resonator might serve (particularly if encased in a tiny evacuated shell) as an internal clock for computers. At higher frequencies (100 MHz) the resonator could serve as a generator of radio waves.