Electromechanical performance of piezoelectric scanning mirrors for medical endoscopy

The electromechanical performance of piezoelectric scanning mirrors for endoscopy imaging is presented. The devices are supported by a single actuating cantilever to achieve a high fill factor, the ratio of mirror area to the combined mirror and actuator area. The largest fill factor devices (74%) achieved 10 degrees mechanical scan range at +/- 10V with a 300 mu m long cantilever. The largest angular displacement of 30 degrees mechanical scan range was obtained with a 500 mu m long cantilever device with a 63% fill factor driven at 40V(pp). A systematic investigation of device performance (displacement and speed) as a function of fabrication and operational parameters including the stress balance in the cantilever revealed unexpectedly large displacements with lack of inversion at the coercive field. An interpretation of the results is presented based on piezoelectric film domain orientation and clamping with supporting piezoelectric film characterization measurements. (C) 2012 Elsevier B.V. All rights reserved.