Size-dependent analysis and experiments of bulk PMN-PT [001] piezoelectric actuator for MOEMS micro-mirrors

Abstract

This paper presents the modeling, fabrication, FEM simulation and validation of a PMN-PT [001], bulk micro-actuator intended for integration in smart Micro-Opto-Electrical-Mechanicals Systems (MOEMS). Unlike the majority of piezoelectric materials, PMN-PT [001]has the ability to generate large-stroke out-of-plane actuation; this is due to its high longitudinal piezoelectric coefficient of up to 4500pm/V. After an introduction on MOEMS actuation, a concise modeling is given. The FEM simulations are then presented, highlighting actuation-induced shape specificities. The focus is placed on planar displacement and on possible shape generation. Actuation reached values as high as 680nm for a 200µm thick layer. Spherical shape generation was also studied. After presenting the fabrication of a basic piezo-patch mirror, the experimental verification is provided, outlining the influence of the contact interface size and nature.

Actuated MOEMS Micro-Mirror Based on PMN PT Piezoelectric Material

“…9 presents the predicted maximum displacement curve of different size actuators coupled with the experimental measures of only the 600x600µm 2 , 700x700µm 2 and 800x800µm 2 . The measured displacement does, however prove consistent as the result for the 600x600µm 2 is very close to previously measured values [13]. The values for the measured displacement on the graph represent the average of 8 independent measures on the 600x600µm 2 , 700x700µm 2 and 800x800µm 2 respectively.…”

“…The objective is to further investigate the usability of a bulk piezo-actuator made of PMN-PT in a MOEMS as a micro-mirror actuator. In [13] the connection between the decrease in measured displacement and the increase of the actuator width has been shown. Here, Finite Element simulation studies on how the usable surface varies with the applied voltage is presented.…”

“…PMN-PT cut and polled along the [001] crystalline direction stands out. Recent improvements in crystal growth techniques have shown the possibility of obtaining values of over 4500pm/V [13] for its piezoelectric coefficients. Studies on the actuation potential of PMN-PT [001] have shown that for a 200µm think film actuation can exceed the 325nm limit [15].…”

Electromechanical Actuators for Haptic Feedback with Fingertip Contact

“…The bulk piezoelectric actuators based on PZT or PMN-PT ceramics working at frequencies in the kHz range typically require hundreds of volts to achieve displacement magnitude of tens of micrometers. This is the biggest obstacle for the practical application [117][118][119][120]. Consequently, these kinds of actuators are always manufactured in large sizes, which is not acceptable for miniaturized systems such as MEMSs.…”