Micro/nanofluidics deal with interfacial and transport phenomena at micro/nanoscale, and they received significant attention in the last two decades largely due to their potential applications in biochemical fields. While the significant promise (aka hype) of micro/nanofluidics is yet to be
realized as envisioned in the 1990s, the importance of micro/nanofluidic physics in practical technologies is widely recognized. Here we present two examples in which micro/nanofluidics physics play a central role in determining the viability and performance of a technology. In the first case, we examine ink-jet based bio-manufacturing, in which cells are delivered with high spatial resolution by ink-jets. While the viability of this technique has long been doubted, we show that, using scaling analysis and computer simulations, cell experiences strong but very brief
shearing, which can explain the apparent success of the technique. By elucidating the flow physics underlying the printing process, we identify the mechanisms responsible for cell damage and suggest methods for alleviating the cell damage during printing. In the second case, we examine the capacitive electrical energy storage using supercapacitors. We show that simple interfacial physics are behind the anomalous enhancement of capacitance in sub-nanometer pores. We show that a fundamentally new regime of fluid transport emerges in the next-generation supercapacitors based on hierarchical nanomaterials, and exciting opportunities exist in harnessing the new flow physics in these materials.