Comb drive actuators are very important microelectromechanical systems structures that are widely used in many applications. They are currently used in force balanced accelerometers, resonant accelerometers and resonant gyroscopes, micro-grippers and micro-engines. In addition, they are extensively used in opto-mechanical subsystems such as switches and variable optical attenuators. The goal of this paper is to present a comb drive actuator model design with ultra-low pull-in voltage to achieve large displacement, deriving the exerted forces equations, mechanical analysis and the most important problems, also comparing with the previous work done to treat these problems.