Nanostructure fabrication and patterning for use in chemical separations and sensors.

摘要

The goals of this research are to make nanostructures with controlled dimensions and to investigate potential applications in chemical separations and sensors. There are three parts involved in this work. The first part is engineered gold nanotube membranes and their applications in protein separations. The membranes have narrow pore size distribution, high selectivity, and they are relatively easily modified to prevent protein adsorption. Because of the low transport rate or throughput through the membrane, two types of driving forces were applied to increase transport flux-application of a transmembrane pressure or a transmembrane potential difference. Size-sieving effect, charge effect and pH effect have been investigated.; The second part of this work is a method developed to increase the efficiency of nanowires as building blocks for supramolecular assembly. The low efficiency results from some recessed nanowires within the template membrane. Oxygen plasma etching has been used to remove part of the polymer template and leave the nanowire ends exposed. By adjusting etching time, the length of the protruding nanowires can be controlled. Besides high efficiency as building blocks, these protruding nanowires can be used to increase electrical contact between the nanowire containing membrane and a substrate metal surface.; In the third part of this work, highly ordered alumina membranes were used as masks to etch substrates such as glass to obtain arrays of nanowells. The depth of the nanowells can be controlled by varying the etch time. The inside and outside of the nanowells can be modified with different chemistries such as hydrophilic and hydrophobic functional groups. Friction measurements with the atomic force microscope have been conducted to obtain the friction difference between the different functional groups. The friction difference shows the interaction difference between the AFM tip and the terminal functional groups on the substrate. Since the inside and outside of the nanowells can be modified with different molecular linkers, desired chemical functional groups or nanoparticles can attach to either the inside or outside surfaces.