Reported presently are two design approaches to improve the performance of an electrothermal in-plane microactuator with "chevron" beams. One incorporates beams with uniform cross sections but nonuniform lengths or tilt angles to accommodate the thermally induced expansion of the "shuttle"; the other incorporates beams with nonuniform cross sections to widen the high-temperature "expansion" zones. It is derived analytically, verified using finite-element simulations, and tested by microfabricating actuators occupying a constrained device area that the incorporation of one or the other proposed features leads to an improved performance figure-of-merit, defined to be the product of the actuation displacement and force. An increase in the figure-of-merit by up to 65% per beam has been measured. [2011-0186]