Nonlinearly modulated digital microactuators for nano-precision digital motion generation

This paper presents a nonlinearly modulated digital actuator (NMDA) for producing nano-precision digital stroke. The NMDA, composed of a digital microactuator and a nonlinear micromechanical modulator, purifies the stroke of the digital actuator in order to generate the high-precision displacement output required for nano-positioning devices. The function and concept of the nonlinear micromechanical modulator are equivalent to those of nonlinear electrical limiters, such as Zener diodes. We design and fabricate both linear and nonlinear modulators, having identical input and output strokes of 15.2 /spl mu/m and 5.4 /spl mu/m, respectively. We compare the characteristics of the linear and nonlinear modulators linked to identical digital actuators. The NMDA shows a repeatability of 12.3 /spl plusmn/ 2.9 nm, superior to the 27.8 /spl plusmn/ 2.9 nm achieved by the linearly modulated digital actuator (LMDA). We experimentally verify the displacement purifying capability of the nonlinear mechanical modulator, applicable to nano-precision positioning devices and systems.