Microactuators are essential elements of MEMS and are widely used in these devices. Microgrippers, micropositioners, microfixtures, micropumps and microvalves are well-known applications of microstructures. In this paper, the design optimization of shape memory alloy microactuators is discussed. Four different configurations of microactuator with variable geometrical parameters, generating different levels of displacement and force, are designed and analysed. In order to determine the optimum values of parameters for each microactuator, statistical design of experiments (DOE) is used. For this purpose, the Souza et al constitutive model (1988 Eur. J. Mech. A 17 789-806) is adapted for use in finite element analysis software. Mechanical properties of the SMA are identified by performing experimental tests on Ti-49.8%Ni. Finally, the specific energy of each microactuator is determined using the calibrated model and regression analysis. Moreover, the characteristic curve of each microactuator is obtained and with this virtual tool one can choose a microactuator with the desired force and displacement. The methodology discussed in this paper can be used as a reference to design appropriate microactuators for different MEMS applications producing various ranges of displacement and force.

Fascinating properties of shape memory alloys, being shape memory effect and super-elasticity, make them unique in comparison to other materials. One of the most common applications of these materials is in actuators as an actuation mechanism. In this research, a shape memory actuator is presented and modeled. The Souza et al. constitutive model is employed in finite element analysis software in order to simulate the shape memory behavior of Nitinol. Ti-49.8%Ni was selected according to the proper characteristics, and its mechanical properties are characterized through experimental tests to the calibrated model for this alloy. The simulation results were further verified by empirical evaluation of a Nitinol actuator.