Composite electric field guided assembly of nano/bio materials: Fluidics controlled regime for micro/nano assembly.

摘要

Nanoscale particles exhibit unique phenomena that enable extremely sensitive sensors and molecular electronic devices. The immobilization of nano/bio materials on electrodes is an essential issue needed to be addressed in order to accomplish such devices. Also, the devices often need to be assembled through the use of micromachining technology to facilitate the implementation of mechanical/electrical/chemical functions in the nano- and/or micro-dimension. Based on this concept, an array assembly method involving an electric field was accomplished through the work presented in this thesis. The technique developed here was successfully applied to multi-walled carbon nanotubes (MWCNTs), single walled carbon nanotubes (SWCNTs) and DNA molecules.; A composite electric field guided assembly method (CEGA) was developed to integrate individual MWCNTs on electrodes and to stretch a single strand lambda-DNA molecule on a gap. The CEGA approach, combining an ac with a dc e-field, was found to successfully manipulate and control the dielectrophoretic and drag force.; The fabrication of nanoscale electrodes is another issue relevant to molecular devices. A technique for the fabrication of nanoscale electrodes, using a MWCNT as a shadow mask, was developed to create a ∼20nm gap. Individual MWCNTs were assembled on the nanoscale electrode by taking advantage of the CEGA method, and its highest packing density was compared with other CNT assembly technologies.; As a potential application of the CEGA approach, a gas sensor using a multi-walled carbon nanotube (MWCNT) was developed. The electrical resistances of large diameter MWCNTs were found to decrease in the presence of air, after experiencing electrical breakdown, while pristine MWCNTs were not appreciably sensitive. Also, a glucose sensor was developed to specifically detect hydrogen gas (H2) diffused from a glucose oxidation reaction. The sensor was composed of metallic MWCNT bundles deposited using an ac electric field.; Through these experiments and analyses, novel nanoscale fabrication methods, combined with standard micromachining processes, were successfully developed with one goal in mind, the mass-production of nanotechnology.