Hybrid MEMS-SMA structure for intraocular lenses

Abstract

This paper presents the design, fabrication and evaluation of a novel ring-shape MEMS micro actuator for a latching mechanism for low power consumption and large displacement linear actuation, which can be applicable for a variable-focus lens system such as an accommodative intraocular lens (AIOL). The proposed actuator consists of a shape-memory-alloy (SMA) ring, parylene spring and shoes. The parylene spring was carefully designed for independent control of radial and axial stiffness, which can be realized by a high aspect ratio cross section and a meander structure. The maximum force generated by the parylene spring was about 50mN. Two types of SMA actuator have been examined for the actuation: simple wire and micro spring types. The SMA in wire shape was evaluated in two configurations. Maximum displacement as high as 300μm was obtained by using the SMA micro spring.