Miniaturized Mechanical Tester for the Multiscale Testing of Biomaterials and Metamaterials

To fully understand the fundamental mechanical behavior that yields extraordinary performance of biomaterials under extreme loading conditions, and establish design rules for predictable mechanical properties, a concerted effort is needed to reduce the complexity of these systems by characterizing their hierarchical structures and the effect of length scale of their components. To this end, this proposal requests funds for the acquisition of the Alemnis mechanical tester and complementary high-temperature and high-dynamics modules to conduct dynamic compression and bending/fracture experiments on nano/micro-scale biomaterials. The system can be interfaced with an existing environmental scanning electron microscope housed in a core facility managed by the PI at Northwestern University. The Alemnis tester is a compact and highly customizable mechanical testing stage capable of testing milli-, micro-, and nano-meter scale samples with unprecedented spatial and temporal force resolution, allowing mechanical tests to be carried out under a variety of loading scenarios. To image deformation and failure in real time, a Phantom v611 high-speed camera is also requested to be interfaced with the Alemnis tester in a Nikon upright microscope. These capabilities would enable novel research to (i) characterize the mechanics of hierarchical architectures found in natural materials (e.g., Bouligand) and understand their ability to withstand a variety of forces such as impact and bending, by studying the strain-rate behavior of the dactyl club of mantis shrimp and the intricate hierarchical structure of beetle exoskeletons, and (ii) explore the structure-property relationships in hollow microlattices, as a function of temperature and strain rate, to gain insight into the biomimetic design of energy-absorbing and energy-harvesting piezoelectric materials. The proposed instrumental capability would provide new curricula for two of the PI’s courses to teach students about current approaches to research in biomaterials and how evolutionary pressures influence material architecture and mechanical performance.