Polyimide Ripples Created with Focused Ion Beam

An interdisciplinary group of scientists from Northeastern University, Korea Institute of Science and Technology, Seoul National University, and Harvard University have developed a new technique to modify the surface structure of polymers on the nanoscale. For the first time, the researchers were able to alter the surface structure of polyimide, a highly durable polymer substrate used in electronic and biomedical engineering, by using focused ion beam (FIB) irradiation to create various predefined shapes and textures. These patterns have numerous applications in science and medicine, including tissue engineering, regenerative medicine and stretchable electronics.

"The goal of this research is to develop novel techniques that will allow for the controlled modification of polymer surfaces," said Ashkan Vaziri, assistant professor of mechanical and industrial engineering at Northeastern University. "Realizing the effects of different parameters of the ion beam results in the creation of controlled patterns for specific applications."

By adjusting the parameters – the incidence angle, the current and the acceleration voltage – of the ion beam, the researchers created various one- and two-dimensional surface features and patterns on the polyimide. The variances in the parameters resulted in the different shape, size, location and distribution of the surface structures.

In addition, the team developed an extension of this method using a maskless patterning technique. Analogous to using a piece of gray-colored glass with varying degrees of darkness to control the radiation from the sun but in the nanoscale, the ion intensity and angle were controlled as it made contact with the polyimide surface, resulting in three-dimensional surface structures.

"Using our technique to engineer surface patterns on polyimide surfaces has a myriad of potential applications in nanotechnology and beyond," added Vaziri.

One such application includes incorporating patterned surfaces, such as microwells and microchannels, into microfluidic devices for cell trappings and cell engineering.

The group's findings were published in the March 2009 issue of Nanotechnology.

Related Departments:Mechanical & Industrial Engineering