Modified asymmetric micro-electrothermal actuator: analysis and experimentation

A modified design to generate large deflection and to control the peak temperature of the hot beam of a two-beam asymmetric thermal microactuator is presented. The analysis undertaken shows that when changing the dimensions of a section of the hot beam, it is possible to achieve a higher average temperature but a lower peak temperature within the hot beam. The design variables have been investigated, and theoretical results from the investigation are reported. The analysis undertaken shows the impact that the hot beam geometry has on the temperature distribution, and how this can be optimized to avoid local hot spots which lead to thermal failure. A dimensionless thermal parameter which determines the temperature distribution is introduced in the analysis. Thermo-mechanical analysis of the modified actuator is also undertaken in order to calculate the deflection of the modified actuator design. Experimental results confirm that this design achieves greater deflection than the classical asymmetric design whose deflection is limited because the temperature in the central part of the hot beam can reach such a high value that the structural material (polysilicon) experiences thermal failure, and is subsequently unusable