Nanoscale printed tunable specimen geometry enables high-throughput miniaturized fracture testing

Abstract

Two-photon lithography (TPL) enables the design of novel micromechanical specimens, down to sub-micron resolution, thus extending the possibilities for device and material characterisation and pushing the boundaries of a broad range of miniaturized technologies such as optics, analytics, and medicine. Employing a push-to-pull geometry, incorporating double edge notched tension specimens loaded in mode I, the specimen manufacturing and testing can be automated to a large extent. This allows for the use of large parameter space characterisation methods as the essential work of fracture, with an experimentally simpler to realize compression testing setup. Within this work, a methodology is outlined for automated specimen direct laser writing with a TPL-device and subsequent testing via a nanoindenter. In total, 2100 specimens were manufactured, of which 1997 could be used for evaluation. Estimations for the essential work of fracture of the used photoresist is presented, with regards to influencing parameters such as testing displacement rate and laser writing power. A discussion of its statistical robustness and validity considerations is included. This will act as a basis framework for further statistical fracture evaluation schemes for other resin materials, as well as for probing thin film systems.