Electrostatic silicon accelerometer

Claim 1

A solid state accelerometer, comprising: a first conductive silicon plate; a conductive silicon frame bonded to said first silicon plate; a first thin insulating oxidized silicon layer located between said first silicon plate and said silicon frame; a second conductive silicon plate bonded to said silicon frame; a second thin insulating oxidized silicon layer located between said second silicon plate and said silicon frame; wherein the bonding of the first and second silicon plates to the silicon frame results in an enclosure sealed from an external environment; a silicon conductive pendulum, situated within the enclosure, said pendulum comprising an epitaxial layer of silicon deposited between two silicon wafers and having at least one conductive silicon flexure connecting said pendulum to said frame; and feedback loop electronics electrically connected to said first and second plates and to said frame; and wherein: said pendulum is located between and approximately equidistant from said first and second plates; said pendulum and said first plate have a first capacitance; said pendulum and said second plate have a second capacitance; the first and second capacitances have first and second original values, respectively, that are nearly equal to each other in absence of any gravitational or acceleration force upon said accelerometer; said pendulum moves slightly upon an occurrence of any gravitational or acceleration force in a direction of a normal axis that intersects said first and second plates and said frame, thereby causing a slight change in the first and second capacitances; any movement of said pendulum from being approximately equidistant between said first and second plates is counteracted by electrostatic forces between said pendulum and said first and second plates, said electrostatic forces being generated by said feedback loop electronics which operate in response to slight changes in the first and second capacitances to provide voltages across said pendulum and said first silicon plate and across said pendulum and said second silicon plate sufficient to move the pendulum to a position approximately equidistant from said silicon plates; and magnitudes of the voltages provided indicate a magnitude of accelerational or gravitational force acting on said accelerometer in a direction approximately parallel to the normal axis.