Nano/Micro Scale Fabrication
Research approaches in nanofabrication have taken two paths, bottom-up approach and top-down approach. Top-down fabrication process starts with larger objects, such as layers of materials deposited on a bulk substrate e.g. silicon wafer, and proceeds to remove defined regions, leaving on the substrate a number of smaller material patterns. In the recent years, top-down process based on photolithography has reached the limit of resolution down to tens-of-nanometers rang (e.g. e-beam lithography), which empowers the routine entry of microelectronics- and MEMS-related processes into the nanotechnology arena. Bottom-up fabrication, by contrast, manipulate molecules and arrange into clusters to form a larger structure, like building blocks of exceedingly small dimensions. Several methods including atomic force microscopy, scanning tunneling microscopy, and optical tweezer have been demonstrated for manipulating the individual molecules. Our research interest, in contrast, is to develop techniques based electrokinetic forces, which has larger degree of freedom, to manipulate molecules. Subsequently, by combining top-down and bottom-up processes, molecular self-assembly can be guided by the EK forces that defined by lithography to fabricate multifunctional nanostructures made of biomoelcules, nano tubes or nano particles.