Patent ID: 8198974

Claim:
An electrostatic actuator comprising: a base including a first electrode; a flexible membrane including at least two material layers of different materials in contact with each other, at least one of the material layers including a second electrode electrically isolated from the first electrode; a gap separating the flexible membrane from the base; the flexible membrane including, a fixed end connected to the base, and a free end opposite the fixed end and spaced apart from the base; said free end of the flexible membrane configured to move relative to the base under an electrostatic force; and said second electrode having at least first and second portions separated by a third portion and in combination the first, second, and third portions defining a first step and a second step provided in a vicinity of said fixed end, and in combination forming a reduced gap space between the base and the flexible membrane, when no pull down voltage is applied, and thereby to reduce a pull-down voltage needed to pull down the flexible membrane from an open no applied voltage position to a closed position, wherein said first step is adjacent to the fixed end and said second step is adjacent to the first step, the first step is closer to the fixed end than the second step, the first portion comprises said fixed end connected to the base, and the third portion is separated from the base by the reduced gap space.