Fabrication Of Nuclear Nanopores And Investigation Of Their Conductive Properties In Electrolyte

With the recent development of nanofabrication techniques, nanopores made of polymer materials, silicon, or silicon containing compounds have begun to replace the original biological nanopores because of their structural stability, good reproducibility and environmental adaptability over the latter. Single nanopores have attracted considerable interest from researchers for their novel applications in the fields of biomimics. chemical and biological analysis, ion transport behavior in nanoscale and design of high quality nanofluidic devices.This thesis is mainly focus on the design of nanodevices based on single polymer nuclear nanopores.With good mastering of ion track etching technique in polymer membranes and further understanding of ion transport behavior inside asymmetric nanopores. the author carried out the following two work around the surface charge which is the essential factor to influence ion distribution in nanopores.(1) Fabracation and electrolytic conduction properties of single conical nanopores. Single conical nanopores were fabricated by etching single-ion-irradiated polymer (ethylene terephthalate) (PET) films. The etching process was monitored by measuring the transmembrane current. A series of conical nanopores with different tip sizes were obtained at different maximum etching currents, "Imax". Results showed that it was possible to control the tip diameter by terminating etching at a certain Imax· The current-voltage characteristic of the nanopores in KC1 solution was investigated. Resulits showed that the ionic conduction was asymmetrical this phenomenon is called rectification. The current rectification coefficient, was influenced by the tip size and electrolyte concentration.(2) Influence of pressure on the electrolytic conduction of conical nanopores. The effect of pressure is shown to be dependent on the pore orifice size. For larger Kapton nanopores. the disruption of cation and anion equilibrium distributions within the nanopore caused by pressure resulted in decreaing of the rectification, but the pressure effect on the Ⅰ-Ⅴ also has some differences for larger nanopores with different radius. For smaller nanopore, pressure has a negligible influence on rectification.(3) Surface modifications of polymer nanopores with atomic layer deposition method. Thermal atomic layer deposition were used to modified polymer nanopores with HfO2. results showed this method was able to achieve a completely modification with good conformality. The stability of nanopore was improved and the rectification characteristic in the electrolyte solution has been keeping well.(4) Preparation of Ag/Cu Janus nanowires with electrodeposition method. Bimetal (Janus) nanowires were achieved by a highly controllable method using track-etched polymer templates. The aperture of nanopores prepared by this templates is uniform、continuously controlled, so the achieved nanowires have uniform pore size and also can be precisely regulated. This polymer template is easily dissolve in organic solvents and organic solvent does not react with the nanowires, make it is easy to release the nanowires into solution. Especially, the nanopore shape in the track-etched templates is adjustable (e.g.conical), more special shape nanowires could be fabricated. Thus, these features make this simple and inexpensive method very suitable for the preparation of Janus nanowire.(5) Electroosmosis-driven polystyrene particles transport across polymer membrane containing a conical-shaped nanopore. When a polystyrene particle is driven translocate through the nanopore, the ionic curve through the nanopore will show a drop. The characteristics of the current give the properties of the charged particle analyzed. When a polystyrene particle transport across the nanopore, the current will fall because of the volume blockage; but the current will increase as a result of electroosmosis. So, the current of the nanopore is the combined action result of these two factors.Among the work mentioned above, ionic conduction of single conical nanopore and the current property when nanoparticles transport through nanopore were measured. The ion transport behavior in nanopore and the pore surface properties were investigated systemly, this research would provide some theoretical basis for the microfluid.