Studies On Nanofluidic Chip Fabrication And Its Applications

The studies on nanofluidic chip have made great progress in recent years. Both the basic and applied research of nanofluidics is based on the nanochip fabrication. It demands more rigorous techniques for nanochip fabrication as the channels downing to nanometer scale. As the channel dimension goes down to nanometer scale, unique properties emerge, for example, overlapped electric double layers, reduced electroosmotic flow, increased viscosity, ion enrichment and depletion. These properties would impact on the nanofluidics application. The topic of this dissertation is focused on the fabrication of the glass nanochips, the research on basic properties of the nanochannels and the ion enrichment and depletion at the terminal of nanochannel under the electric field.In Chapter 1, various fabrication techniques of nanofluidics were reviewed, including sacrificial layer technology, bulk/film-machining, chemical-mechanical polishing method, mold-machining method, and so on. The recent research on nanofluidis properties and application was also introduced.In Chapter 2, the techniques of nanochannel fabrication of glass substrate and the chip bonding were developed. Glass nanochannels were achieved by ultraviolet lithography and wet chemical etching. Smooth inner surface of the nanochannel was gotten by optimizing the composition of the etchant. The temperature of etching and the concentration of the etchant were optimized. The depth of the nanochannel was tuned by controlling the etching time. Good reproducibility in depth of 6.8% (n=5) was achieved by inter-day preparations. The substrate was bonded with the cover plate by room-temperature bonding technique. The minimum aspect ratio (depth to width) of 5.0×10^-5 was achieved.In Chapter 3, the double etching technique was developed to fabricate nanofluidic chip which integrated nanochannel with microchannels the same substrate. The problem of dislocation of channels could be avoided and more than 90% bonding yield for the substrates was achieved using this simple technique.In Chapter 4, the research on hydrokinetics and electroosmotic flow of nano channels was studied. The stream flows through the nanochannel under the capillary effects. It was found that the flow spread ahead rulelessly with air bubble in. Current-monitoring measurement method was used to study the electroosmotic flow of nano channel. Ion enrichment and depletion was also demonstrated at the terminals of nanochannels under the electric field using the integrated nanofluidics.