Chapter 6: Nanofluidics for Biomolecular Detection

Nanofluidics, defined as the fluid flow with at least one dimension below 100 nm, has resulted in a wide range of novel transport phenomena. Compared to macrofluidics or microfluidics, the substantially enhanced surface-to-volume ratio of nanofluidic structures has provided a unique possibility to manipulate fluid flow via the geometrical boundaries. For example, the electrical double layers (EDLs) that are induced by the channel wall surface charges now get overlapped due to the nanoscale constriction. In this way, the fluid becomes charged over the whole volume, which is in sharp contrast to the macroscale counterpart where the nanometre-thick EDLs are completely negligible in comparison to the net volume. By further imposing an electrical field, the charged nanofluidics would obtain an additional term of driving force and so the associated movement. In this manner, an electrokinetic tuning of nanofluidics is readily achieved by controlling electrical properties of the nanofluidic system. The above capability of manipulating nanoscale fluidics opens avenues to diverse fields in nanoscience and nanotechnology. One interdisciplinary topic is the regulation of biomolecule motion in the nanofluidic environment, which may address one critical challenge in 3rd generation genome sequencing technology. In this chapter, we are going to demonstrate several strategies and principles of controlling biomolecule motion through the manipulation of nanofluidics.