SU-8 Electrothermal Actuators: Optimization of Fabrication and Excitation for Long-Term Use
AbstractIn 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. View Full-Text
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Winterstein, T.; Staab, M.; Nakic, C.; Feige, H.-J.; Vogel, J.; Schlaak, H.F. SU-8 Electrothermal Actuators: Optimization of Fabrication and Excitation for Long-Term Use. Micromachines 2014, 5, 1310-1322.
Winterstein T, Staab M, Nakic C, Feige H-J, Vogel J, Schlaak HF. SU-8 Electrothermal Actuators: Optimization of Fabrication and Excitation for Long-Term Use. Micromachines. 2014; 5(4):1310-1322.Chicago/Turabian Style
Winterstein, Thomas; Staab, Matthias; Nakic, Christian; Feige, Hans-Jürgen; Vogel, Jürgen; Schlaak, Helmut F. 2014. "SU-8 Electrothermal Actuators: Optimization of Fabrication and Excitation for Long-Term Use." Micromachines 5, no. 4: 1310-1322.