Silicon linkage with novel compliant mechanism for piezoelectric actuation of an intraocular implant

An implantable mechatronic microsystem is a new approach to restore the accommodation ability of the human eye. For change of refractive power a lens shift is performed by an actuator. This paper reports on the first actuator solution for such an implant. It is based on a piezoelectric bender the displacement of which has to be amplified in a very limited design space to sufficiently drive the optics of an Artificial Accommodation System. This challenge is solved by a novel compliant mechanism realized in single-crystal silicon that additionally ensures the tilt-free translational displacement of the lens required for optical imaging quality. The design is free of any surface-friction to achieve high durability. Finite element analysis is conducted to calculate and optimize the performance of three linkage design variants. They were fabricated on a scale of 1.5:1 using deep reactive ion etching. Measurements were carried out to characterize the geometry, elastic behavior, and kinematic performance of the linkage samples. The results are in very good agreement with the calculations and indicate sufficient amplification of the piezoelectric bender's displacement by the linkage to generate the required lens shift.