Micromachines | |
SU-8 Electrothermal Actuators: Optimization of Fabrication and Excitation for Long-Term Use | |
Thomas Winterstein1  Matthias Staab1  Christian Nakic1  Hans-Jürgen Feige2  Jürgen Vogel2  Helmut F. Schlaak1  | |
[1] Microtechnology and Electromechanical Systems Laboratory, Institute of Electromechanical Design, Technische Universität Darmstadt, Merckstr. 25, 64283 Darmstadt, Germany; E-Mails:;Laboratory of Experimental Solid and Micro Mechanics, Faculty of Automotive Engineering, Westsächsische Hochschule Zwickau, Dr.-Friedrichs-Ring 2A, 08056 Zwickau, Germany; E-Mails: | |
关键词: electrothermal actuator; SU-8; long-term stability; pseudo-bimorph; glass transition temperature; | |
DOI : 10.3390/mi5041310 | |
来源: mdpi | |
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【 摘 要 】
In this paper we examine the suitability of SU-8 2000 as a construction material for electrothermal actuators and the actuator stability for long-term operation. The fabrication of SU-8 was optimized for mechanical and thermal stability. Samples with different softbake duration, exposure dose and postbake temperature were evaluated using Fourier-Transform IR-spectroscopy and dynamic-mechanical analysis. The exposure dose and postbake temperature proved to have a strong influence on the cross-linking and the glass transition temperature. A final hardbake levels the effects of the process history. A high degree of crosslinking, a low drop of the dynamic modulus over temperature (30%) up to the glass transition temperature 100–140 °C were achieved for SU-8 with an exposure dose of 1500 mJ/cm², a postbake temperature of 95 °C and hardbake of 240 °C. Electrothermal actuators proved to be stable until the end of the experiment after 2400 duty cycles. Actuator deflections up to 55 μm were measured (actuator length: 4 mm) for input powers up to 160 mW and a maximum operating temperature of 120 °C. Higher temperatures led to permanent deformations and failure. An offset drift of up to 20% occurs during actuation, but converges after a burn-in phase of about two hours.
【 授权许可】
CC BY
© 2014 by the authors; licensee MDPI, Basel, Switzerland.
【 预 览 】
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