Nanofluidics is often defined as the study and application of fluid flow in and around nanosized objects and deals with the manipulation and control of a few molecules or minute quantities of fluids. The invention and wide availability of many new technological tools like atomic force microscope (AFM) and scanning tunneling microscope (STM) (both for inspection and creation of nanostructures), the electron, X-beam and ion-beam lithographs, and the development of new micromachining techniques like soft lithography and bottom-up assembly methods has made the study and application of nanofluidics much more accessible, and allows a previously unknown measure of control on the nanoscale.
Applications
Nanofluidic devices are made by etching tiny channels on silicon or glass wafers, typically using photolithography. These devices have relatively simple structures, with the branched channels having the same depths.
Nanofluidics finds application in many diverse fields; particularly biology is an important discipline for nanofluidics, because biological organisms on their primary cellular level function in a nanofluidic environment. A number of applications of nanofluidics have already been use, like the use of charged polymers for lubrication, the lotus effect for self-cleaning surfaces, membranes for filtering on size or charge (e.g. for desalination) and nanoporous materials for size exclusion chromatography. In separation science it is used for the size fractionation in regularly structured micro arrays. Another area of nanofluidic applications has been the study of fundamental properties of liquids and molecules, e.g. in biophysics and fluid mechanics, where nanofluidics offers the possibility to confine molecules to very small spaces or to subject them to controlled forces and to extract fundamental knowledge.
Nanofluidic devices have been mainly used to analyze DNA and proteins; it could also be useful in the preparation of nanoparticles for gene therapy, drug delivery, and toxicity analysis. The device could be useful for sorting and measuring nanoparticles that are employed for drug delivery and gene therapy.
Nanofluidic structures are naturally applied in situations demanding that samples be handled in exceedingly small quantities, including Coulter counting, analytical separations and determinations of biomolecules, such as proteins and DNA, and facile handling of mass-limited samples. Application of nanofluidics is also to Nano-optics for producing tunable micro lens array, development of lab-on-a-chip devices for PCR and related techniques.
Challenges
There are many challenges associated with nanofluidics when applied to the flow of liquids through carbon nanotubes and nanopipes because of channel blocking due to large macromolecules and insoluble debris in the liquid.