On the dynamics of a micro-gripper subjected to electrostatic and piezoelectric excitations

• Nonlinear statics and dynamics of a MEMS gripper have been investigated.
• During the contact, the particle has been modeled as a linear spring.
• The instability region on the plane of governing parameters is investigated.
• During the contact, stress analysis has been performed on the levers of the gripper.
• The equations have been solved using numerical integration and multiple time scales method.

The aim of this study is to investigate the mechanical behavior of an electrostatically actuated functionally graded piezoelectric micro-gripper. The presented micro-gripper includes two clamped–clamped microbeams symmetrically located against each other in vertical direction. The microbeams are composed of silicon and Piezoelectric Material based on Lead Zirconate Titanate. The mechanical properties, including elasticity modulus, density, and piezoelectricity coefficient are varied exponentially along the height of the microbeam based on power law distribution. The microbeams undergo simultaneous electrostatic and piezoelectric excitations. Two main sources of nonlinearities including geometrical nonlinearity and electrostatic force dominate the dynamics of the gripper. The temporal response is determined by numerically integrating the motion equations and verified by means of method of multiple scales. The contact with the particle is modeled as linear spring which increases the overall stiffness of the grippers. The stability analysis is performed and the pull-in voltage of the device is determined.