Experimental and numerical investigations of microthermal actuator employing the amplification theory for achieving competitive performance.

Abstract

The past decade has seen the rapid development of microthermal actuators designs; this is due to their wide usage in various sectors such as biomedical applications and communication. This study presents the experimental assessment, fabrication, and numerical simulation of a novel thermal actuator device applying the amplification theory to achieve competitive overall performance. The device consists of two L-shape lever and half-bridge amplification mechanisms accompanied by microthermal actuators forming all a compliant system. The input displacement is amplified at the output by about 3.55 as a multiplication ratio. Experimental characterization has been performed over a wide voltage range reaching 15 V and achieving 19 μm actuation. Considering how the material's properties change with temperature and their effect on the simulation results has been proven critical upon comparing experimental with the numerical results. The simulation has shown consistency with experimental results only when employing temperature-dependent models up to a voltage of 12 V achieving 12.9 μm actuation, unlike assuming constant parameters which is widely used in literature that shows noticable deviation throughout characterization range. Additionally, when designing an effective micro electrothermal actuator, there are other parameters that need to be considered besides high output displacement. Therefore, the comparison with other designs has included all the main specifications that are of concern. The performance is discussed based on the main features of any thermal actuator: displacement, temperature, area, and applied voltage, all combined in a performance evaluation index (PEI). The importance of this index is that it evaluates the overall effectivness of a thermal actuator, whereas one can have excellent performance for one of aforementioned features at the expense of the others, which may degrade the total assessment. Our device shows the highest value of this index of 0.0021 μm/mm²/K/V at applied voltage of 10 V mapping to the lowest temperature profile at 617.5 K and smallest area among its credible counterparts.