May 27, 2009
Focused ion beam forms nanopatterns on soft surfaces
Focused ion beam (FIB) processing has unique capability for rapid prototyping because it requires neither master nor resist in processing. Such direct writing requires no subsequent pattern transformation either. Some substrates are easier to work with than others. In particular, fabricating patterns on an insulating and extremely soft material can be challenging due to charge accumulation and interaction between ions and soft substrates. Here the application of an electrically conductive coating on the sample surface is often necessary to overcome charging problems associated with the primary ion beam. However, this is not always suitable or feasible.
In our recent study, which was published in Nanotechnology, low dose FIB processing was performed on extremely soft polymeric material (PDMS) by flooding an electron beam simultaneously on the fabricated area to relieve charge accumulation.
The proposed approach for the fabrication of ordered nanostructure arrays using a FIB could provide a promising way of constructing various functional structures or devices on electrically insulating surfaces such as biotemplates, microlenses, multifunctional microfluidic devices and waveguides with diffractive optical structures.
Systematic studies focusing on protein nanopatterning and high-throughput bioassays are underway in the group's lab based on the well defined nanodot and nanohole arrays.
About the author
Li Guan is a PhD candidate in Prof. Chen Wang's group at the National Center for Nanoscience and Technology (NCNST). She is now exploring using FIB or EBL techniques for making nanopatterned surfaces for bioassay application. Another related research project is to study the electro-wetting phenomenon on nanofabricated dielectric surfaces. Kaiwu Peng is a technical staff member at NCNST working on structural fabrication using EBL and FIB techniques. Prof. Yanlian Yang's research interests include supramolecular nanostructures on surfaces and application of electric force microscopy for studying nanoscale dielectric properties. Prof. Xiaohui Qiu's research is focused on scanning tunneling microscopy and electrical characterization of nanostructured materials. Prof. Chen Wang's research focuses on surface physics and chemistry, and characterization of biomolecular processes and nanostructures by scanning probe microscopy.