Design and characterization of a low temperature gradient and large displacement thermal actuators for in situ mechanical testing of nanoscale materials

The design, fabrication and characterization of a recently developed test platform for the characterization of nanoscale properties of thin films are presented. Platforms are comprised of a microfabricated cascaded thermal actuator system and test specimen. The cascaded thermal actuator system is capable of providing tens of microns of displacement and tens of milli-Newton forces simultaneously while applying a relatively low temperature gradient across the test specimen. The dimensions of the platform make its use possible in both the scanning/transmission electron microscope environments and on a probe station under an optical microscope. Digital image correlation was used to obtain similar accuracy (∼10 nm) for displacement measurements in both a SEM and under an optical microscope. Proof of concept experiments were performed on freestanding 250 nm thick Pt thin films.