Subsidence of Additively-Manufactured Cages in Foam Substrates: Effect of Contact Topology.

Subsidence of implants into bone is a major source of morbidity. The underlying mechanics of the phenomenon are not clear, but are likely related to interactions between contact stresses and the underlying porous trabecular bone structure. To gain insight into these interactions, we studied the penetration of three-dimensional (3D)-printed indenters with systematically varying geometries into Sawbones® foam substrates and isolated the effects of contact geometry from those of overall contact size and area.

Detachment of compliant films adhered to stiff substrates via van der Waals interactions: role of frictional sliding during peeling.

The remarkable ability of some plants and animals to cling strongly to substrates despite relatively weak interfacial bonds has important implications for the development of synthetic adhesives. Here, we examine the origins of large detachment forces using a thin elastomer tape adhered to a glass slide via van der Waals interactions, which serves as a model system for geckos, mussels and ivy. The forces required for peeling of the tape are shown to be a strong function of the angle of peeling, which is a consequence of frictional sliding at the edge of attachment that serves to dissipate energy that would otherwise drive detachment.

Flow switching in microfluidic networks using passive features and frequency tuning.

Manipulating fluids in microchips remains a persistent challenge in the development of inexpensive and portable point-of-care diagnostic tools. Flow in microfluidic chips can be controlled via frequency tuning, wherein the excitation frequency of a pressure source is matched with the characteristic frequencies of network branches. The characteristic frequencies of each branch arise from coupling between fluid in the channels and passive deformable features, and can be programmed by adjusting the dimensions and stiffness of the features.