Determination of thermal and mechanical properties of SU-8 using electrothermal actuators

Abstract

Microelectromechanical systems (MEMS) are small-scale devices capable of producing motion using electrical energy as input. In this work, we present the determination of thermal and mechanical properties of SU-8, which is an emerging structural material for MEMS applications. We have experimentally calculated the coefficient of thermal expansion (CTE), thermal conductivity, and specific heat capacity of SU-8 as 29.68 ppm °C−1, 0.17 Wm-1K-1, and 1.6 Jg-1K-1, respectively. We observe a non-linear relationship between the input power with the displacement achieved by an SU-8-based thermal actuator because of the hyperelastic behavior of the material. The non-linearity in the experimental results has been explained using the two-parameter Mooney–Rivlin model. With our experimental data, we found the parameters for the uniaxial tensile stress, as s1= 0.035 ± 0.002 Pa and s2= - 0.225 ± 0.002 Pa, respectively. Graphical abstract: [Figure not available: see fulltext.].