Researchers Grow Liquid Crystal:
In previous studies , the team produced patterns “defects” votes disruptions repeating patterns found in liquid crystals, in grids and rings nanometer scale. A three-dimensional matrix in the form of a flower : The new study a more complex pattern of an even simpler template is added.
And because the petals of this ” bloom ” are made transparent liquid crystal and radiates outward in a circle from a center point , the assembly resembles a compound eye and therefore can be used as a lens .
The team consists of Randall Kamien , a professor in the School of Arts and the Department of Physical Sciences and Astronomy ; Kathleen Stebe , the School of Engineering and Associate Dean of Applied Sciences for research and professor of Chemical and Bio molecular Engineering and Shu Yang , professor of Engineering departments Materials Science and Engineering and Chemical and Bio molecular Engineering . Members of their laboratories also contributed to the new study, including lead author Daniel Beller , Mohamed Gharbi and Apiradee Honglawan .
Ongoing work of researchers with liquid crystals is an example of a growing field of nanotechnology known as “directed assembly” , in which scientists and engineers aim to manufacture structures on smaller scales without that each component individually manipulated . Rather, the starting conditions are set precisely defined and allow the physics and chemistry that govern these components do the rest.
The starting conditions in the experiments of previous investigators were templates consist of small stalls . In one of his studies, which showed that changing the size , shape and spacing of these posts would result in corresponding changes in the patterns of defects on the surface of the liquid crystal resting on top of them . In another experiment , the researchers showed that they could make a ” hula hoop ” defects around the individual poles , which then act as a second model for a ring of surface defects .In his latest work , the researchers used a much simpler signal.
“Before these liquid crystals were growing into something like a trellis, a template with precisely ordered features,” Kamien said. ” Here , we are planting a seed. ”
The seeds , in this case , silica beads were – essentially polished sand grains . Planted on top of a pool of crystal flower-like patterns of liquid defects grow around each bead . The key difference between the template in this experiment and those in the earlier work of the research team was the shape of the interface between the template and the liquid crystal.
In their experiment that generated defects grid patterns , these patterns are derived from the signals generated by microposts templates . Domains elastic energy originated in the tops and edges of these flat positions and traveled to the liquid crystal layer , culminating in defects. Using a cord instead of a message , as the researchers did in their last experiment , made so that the interface is no longer flat .
“Not just the interface at an angle is an angle that keeps changing , ” Kamien said. ” The way in which the liquid crystal responds to it is that makes these petal shapes in smaller sizes and smaller, trying to match the angle of the pearl until everything is flat. ”
The surface tension in the bead also makes it so that these petals are arranged in one of the convexly levels. And because the liquid crystal can interact with light , the whole can function as a lens, focusing the light to a point below the bead.
“It’s like the compound eye of an insect, or mirrors in larger telescopes,” Kamien said. ” As we learn more about these systems , we will be able to do this type of lenses to order and use them to direct the light . ”
This type of directed assembly could be useful in the manufacture of optical switches and other applications .