RESONANT GUAGE WITH MICROBEAM DRIVEN IN CONSTANT ELECTRIC FIELD

摘要

A resonant strain gauge includes a beam attached at both ends to a substrate. A cover cooperating with the substrate encloses the beam within a sealed vacuum chamber. A first bias electrode is formed on the cover and a second bias electrode is formed on the substrate directly beneath and spaced apart from the beam. The first and second electrodes are biased at constant voltage levels of equal magnitude and opposite polarity. A drive electrode is formed on the beam at one end of the beam. A piezoresistor is formed on the other end of the beam. A shield electrode is located between the drive electrode and the piezoresistor. The drive electrode, ordinarily biased at ground, is selectively charged by applying an oscillating drive voltage to cause mechanical oscillation of the beam. The piezoresistor detects the position of the beam. Beneficially, the piezoresistor detects the position of the beam with the use of a linear force applied to the drive electrode and with minimal impact from parasitic capacitance.