Vibration Analysis of U-Shaped Beam Electrothermal Microactuators
This paper presents an analytical model for the vibration analysis of a U-shaped electrothermal microactuators. A U-shaped electrothermal microactuator has a unique geometrical structure which consist of, interconnected multiple thick and thin beam segments. In this proposed model, both the longitudinal and lateral deflections of each beam segment are incorporated. To facilitate the modelling process, a thick beam is replaced by the thin beam segment using the artificial Young's modulus and density so that the deformation and inertia force of the thin beam can be used to equivalently describe that of the thick beam segment. The relationship of the force and deflections in both longitudinal and lateral directions at connected points between adjacent beam segments is formulated with continuity conditions. The frequency equation is then established subjected to two both boundary and continuity conditions. Solving the frequency equation yields the natural frequencies of the U-shaped beam actuator. The analytical results are compared with the finiteelement simulation results using ANSYS software. A good agreement is observed between analytical and simulation data, and hence the proposed vibration analysis model is verified. This model provides the first insight study on the vibration analysis of U-shaped electrothermal actuators, which is essentially crucial to dynamic system modelling, control, and dimension optimizations.
Experimental Testing and Performance Comparisons between V - and Z-shaped Electrothermal Microactuators
This work presents comprehensive experimental studies on performance comparisons between V - and Z-shaped electrothermal microactuators. The V - and Z-shaped electrothermal microactuators are fabricated by depositing a copper layer on each side of SU-8 photoresist. The steady-state output displacement and dynamic responses of V - and Z-shaped actuators are compared based on experimental testing. In addition, a unique actuator with mixed V - and Z-shaped beams is designed and tested to further compare the force output capabilities of the V - and Z-shaped beams. Experimental data is acquired based on image processing, and a parallel spring model is proposed to analyze the experimental results. Comprehensive discussions are given to provide insights and guidance on the selection and design of the V - and Z-shaped electrothermal micoactuators.
The Effect of Thermal Boundary Conditions and Scaling on Electro-Thermal-Compliant Micro Devices
Electro-thermal micro actuators that operate by virtue of constrained thermal expansion induced by Joule heating, have recently received considerable attention. We use electro-thermal actuation to create monolithic compliant devices with embedded actuation in which the actuator and the mechanism are indistinguishable. These devices can be made at micro (micron size) or meso (hundreds of microns to a millimeter size) scales using any conducting material. In this paper, we examine the scaling effects on these devices, and also present a comparative study of essential and natural boundary conditions used in the thermal analysis. The experimental data and the results of comprehensive analysis that includes conduction through the substrate and the air-gaps; convection; and radiation, are used to make some observations that are generally applicable to electro-thermal-compliant micro devices.