Design and simulation of an optimized electrothermal microactuator with Z-shaped beams

Abstract

The displacement of the central shuttle of a Z-shape chevron actuator can be calculated using a developed approach from other authors. Who demonstrated that the actuators with this geometry offer a larger displacement compared with V-shape actuators. Z-shape offers a larger stiffness and output force for the case of only one arm. This paper is focused on the optimization of the Z-shaped beams of a chevron actuator of eight beams, which seeks to increase the previously described response. The structure is designed in parametric solid modeling 3D software Autodesk Inventor, and simulated by finite element method in Ansys 15.0. These simulations were implemented considering several modifications on the length of the Z-shaped beams in order to choose the most appropriate length. The electric potential applied in all cases was from 0.2 V up to 5 V. The Z-shape length of the arms for the case of the optimized Z-shape actuator increases the shuttle’s displacement in approximately 50% compared to V-shape actuator, and 38% compare to the original Z-shape. Analytical adjusted approach is extremely matched with the simulations results. Length of the Z-shape beam is the determinant factor of the displacement. The low stiffness of the optimized Z-shape actuator (89% lower than the original V-shape and 58% compared to Z-shape) can allow its use as load sensor.

Closed-form modelling and design analysis of V- and Z-shaped electrothermal microactuators

“…. This indicates the measured displacement is a second-order function of voltage, as revealed by the analytical model as in (12). Large deviation occurs when the voltage exceeds certain values.…”

“…Despite the difference in nature, the voltage and external force are equivalent in terms of generating actuator displacement and force. Rewriting (12), we have where…”

“…Electrothermal microactuators have been widely used in designs of microelectromechanical systems (MEMS) for various applications due to their virtues of compatibility, stability, and capabilities in producing high forces and large displacements at lower actuation voltages [1][2][3][4][5]. Among various configurations of the electrothermal actuators, the U-shaped [6,7], V-shaped [8][9][10], and Z-shaped [11,12] types are three typical types to produce in-plane motions. The U-shaped actuator utilizes asymmetrical thermal expansions of two beams with different cross-sectional areas to produce circular arc displacements, whereas the V-shaped and Z-shaped ones can generate rectilinear displacements due to their symmetrical beam structures.…”

“…The reasons include: (1) at lower temperatures material properties do not have a significant change; (2) the change due to the variation of the material property parameters cancels out each other to a certain degree. For instance, on one hand, the electric resistivity ρ and thermal conductivity k a increase with increasing temperature [2,27] causing the decreases in final displacement, as illustrated in the model (12). On the other hand, thermal conductivity k of polysilicon decreases with increasing temperature [2,27], and the coefficient of thermal expansion α increases with increasing temperature [2,27], both resulting in increases of the displacement.…”

Adjustable static and dynamic actuation of clamped-guided beams using electrothermal axial loads

“…The results showed that these structures may have high mechanical stiffness; which limits their actuation bidirectionally and may increase the required thermal voltages for their operations. Teopoyoti -Torres et al [22] optimized the Zactuators based on a finite element model. The results show 50 % increases in the displacement compared to Vshape actuators.…”