Low Dimensional Nanomaterrials Assemblies Based On Dielectrophoresis Technology

Owing to the extra small dimension that is in the same order of magnitude oreven less with electromagnetic wave, de Broglie wavelengths et al, nanomaterial’soptical, electrical, magnetical and some other physical properties undergo a majorchange compared with bulk ones. Besides that, because of the smaller size, the moresurface atoms will occupy the general, the surface active sites will also dramaticallyincreased, which means that the chemical properties will change significantly agreat change. All of these make the nanoscience and nanotechnology drawworldwide attention in the last decades.So far, several kinds of nanomaterials that catch one’s special attention havebeen greatly developed, especially their preparation methods, some goods alsoappeared. So, in the research point, how to effectively integrate the nanomaterialsinto a functional device in a inexpensive way, and maximize the excellent nature ofthe nanomaterials is becoming increasingly important. Recently, the researches onmanipulating the nanomaterails with dielectrophoresis method demonstrated theunique superiority, and received widespread concern.Firstly, in this thesis, we focus on zero-dimensional nanomaterial (CdTequantum dots) assembly with dielectrophoresis method. On the basis of theprinciple of DEP, we fabricated the T-shaped microelectrode arrays usingconventional photolithography technology, and successfully assembled the QDs intomicro bridge-like structures, the considerable fluorescence observed fromfluorescence microscopic images and several orders of magnitude higherphotocurrent (UV light field comparing with dark field) from the I-V test allindicate that the assembly process did not destroy the optoelectronic properties ofthe quantum dot itself, it means that the microbridges have the photoelectric activity.Then, we analyzed how the nanocrystals can be assembled with DEP method. Theresults of the calculation and analysis indicate that the pre-assembly of the QDs intosuper-particles greatly facilitate the subsequent assembly, this pre-assembly notonly saved the pristine properties of the QDs, but enhanced the dielectrophoreticforces to overcome the Brownian force, finally accomplish the DEP assembly.These DEP bridges of quantum confined NPs can be used in fast parallelmanufacturing of novel MEMS components, sensors, and optical and optoelectronicdevices.Then, we designed and fabricated the probe-flat electrode pairs, assembled theCdTe QDs into willow leaf like structure, which made contribution to nanomaterial three-dimensional assembly region.Secondly, we explored the one-dimensional nanomaterials (typicalsingle-walled carbon nanotubes) assembly into three-dimensional architecturesmaking use of DEP method. We designed and fabricated the bridge-likemicroelectrodes, using them we assembled the SWNTs into membrane structurewhich vertically standing on the substrate, the membrane is an assembly withm-SWNTs enriched according to the Raman spectrum, the SEM images indicatethat the nanotubes is arranged partial order. The self-standing, eliminating thethird-party contacted SWNT membrane can be used in biosensor, photoelectricaldevices, and can be integrated into microfluidics chips commendably, owns greatpotential in biomedical field.