Seunghun Hong

A MEMS nanoplotter with high-density parallel dip-pen nanolithography probe arrays

We report on the development of a nanoplotter that consists of an array of microfabricated probes for parallel dip-pen nanolithography. Two types of device have been developed by using microelectromechanical systems micromachining technology. The first consists of 32 silicon nitride cantilevers separated by 100 µm, while the second consists of eight boron-doped silicon tips separated by 310 µm. The former offers writing and imaging capabilities, but is challenged with respect to tip sharpness. The latter offers smaller linewidths and increased imaging capabilities at the expense of probe density. Parallel generation of nanoscopic monolayer patterns with a minimum linewidth of 60 nm has been demonstrated using an eight-pen microfabricated probe array.

Conductance Microscopy for Electric Conduction Study of Bio-Inspired Hybrid Nanostructures under Ambient Conditions

Electrical conductance of single stranded DNA (5′-TTT TTT TTT T/3 Thio MC3-D/-3′) monolayer patterns on Au surface is compared with those of various organic molecular patterns via the conductance microscope (CM) technique that allows one to take nanoscale conductance images utilizing a conducting AFM tip in contact mode AFM. In the experiment, reference molecules and ssDNA are patterned on the same substrate via direct deposition methods such as dip-pen nanolithography and microcontact printing. Then, conductance microscope image is recorded revealing the relative conductivity of ssDNA patterns relative to various reference molecules. 16-mercaptohexadecanoic acid and 2-mercaptobenzimidazole patterns are found conducting better than the ssDNA patterns. This result indicates that the ssDNA with 10T bases is a relatively poor electrical conductor. The capabilities of CM technique are also tested on various nanostructures including the single wall carbon nanotube junction.