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futurity_sci_tech 00908.txt

#Ink-jet printing creates soft nanostructures A new way to make nanostructures combines advanced ink-jet printing technology with block copolymers that spontaneously form ultra-fine structures. The new approach could have applications for the semiconductor and magnetic storage industries. Researchers were able to increase the resolution of their intricate structure fabrication from approximately 200 nanometers to approximately 15 nanometers. A nanometer is a billionth of a meter the width of a double-stranded DNA molecule. The ability to fabricate nanostructures out of polymers DNA proteins and other oftmaterials has the potential to enable new classes of electronics diagnostic devices and chemical sensors. The challenge is that many of these materials are fundamentally incompatible with the sorts of lithographic techniques that are used traditionally in the integrated circuit industry. Recently developed ultra high-resolution ink jet printing techniques have some potential with demonstrated resolution down to 100-200 nanometers but there are significant challenges in achieving true nanoscale dimension. ur work demonstrates that processes of polymer self-assembly can provide a way around this limitationsays John Rogers professor of materials science and engineering at University of Illinois at Urbana-Champaign. Combining jet printing with self-assembling block copolymers enabled the engineers to attain the much higher resolution as suggested by lead author Serdar Onses a postdoctoral scientist at Illinois. Onses earned his doctorate at the University of Wisconsin under Paul Nealey now professor of molecular engineering at the University of Chicago and a co-author of the paper in Nature Nanotechnology. his concept turned out to be really usefulrogers says. Engineers use self-assembling materials to augment traditional photolithographic processes that generate patterns for many technological applications. They first create either a topographical or chemical pattern using traditional processes. For the new paper this was done at imec in Belgium an independent nanoelectronics research center. The resolution of the chemical pattern nears the current limit of traditional photolithography notes Lance Williamson a graduate student in molecular engineering at University of Chicago and co-author of the article. mec has the capability to perform the photolithography at this scale over large areas with high precisionwilliamson says. Back at the University of Illinois engineers place a block copolymer atop this pattern. The block copolymer self-organizes directed by the underlying template to form patterns that are at much higher resolution than the template itself. Previous work has focused on the deposition and assembly of uniform films on each wafer or substrate resulting in patterns with essentially only one characteristic feature size and spacing between features. But practical applications may need block copolymers of multiple dimensions patterned or spatially placed over a wafer. his invention to use ink-jet printing to deposit different block copolymer films with high spatial resolution over the substrate is highly enabling in terms of device design and manufacturing in that you can realize different dimension structures all in one layernealey says. oreover the different dimension patterns may actually be directed to assemble with either the same or different templates in different regions. he advanced form of ink-jet printing the engineers use to locally deposit block copolymers is called electrohydrodynamic or e-jet printing. It operates much like the ink jet-printers printers office workers use for printing on paper. he idea is flow of materials from small openings except e-jet is a special high-resolution version of ink jet-printers printers that can print features down to several hundred nanometersonses says. And because e-jet can naturally handle fluid inks it is suited exceptionally well for patterning solution suspensions of nanotubes nanocrystals nanowires and other types of nanomaterials. he most interesting aspect of this work is the ability to combine top down techniques of jet printing with â##bottom upâ##processes of self-assembly in a way that opens up new capabilities in lithographyâ##applicable to soft and hard materials alikerogers says. he opportunities are in forming patterned structures of nanomaterials to enable their integration into real devices. I am optimistic about the possibilities. esearchers from Hanyang University in Korea also contributed to the study which received funding from the National Science Foundation and National Research Foundation of Korea t

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