Liquid crystal mystery solved after 10 years

Abbey Stirgwolt

Most people would be content to spend a Sunday afternoon vegging in front of a 76-inch TV screen.

Fewer would be willing to spend a Sunday afternoon – or any afternoon, for that matter – researching how that TV screen works.

For the past 10 years, physics professor Satyendra Kumar and his colleagues have devoted their time to solving that mystery by conducting a study on the alignment of liquid crystals.

Kumar and his team of two students and “at least two post-docs” recently made a landmark discovery in the field of liquid crystals, and thanks to their findings, computer screens, televisions and other LCD technology may eventually become cheaper and more efficient.

The team’s basic testing method, on the most fundamental level, involved rubbing a linen cloth over a series of polymer-coated surfaces, all containing liquid crystals: the same as a TV screen, a computer screen or a cell phone display screen. This rubbing causes the crystals to align.

“We tested over 100 glass surfaces,” Kumar said. Different types of cloth and ultraviolet rays, which produce the same effects, were also used in the tests. Combinations of these variables comprised the team’s research.

“When you rub a surface, you are creating surface roughness,” Kumar said. The scientific term for this is isotropy.

Kumar explained isotropy in this way: The teeth of a comb, for example, run parallel to one another, all facing one direction. If a person rubs his or her hand parallel to the direction of the comb’s teeth, this is classified as “smooth,” because there is little resistance.

However, if a person moves his or her hand in a perpendicular direction to the comb’s teeth, there is resistance because the direction of movement is perpendicular to the comb’s ridges.

Kumar and his colleagues discovered that this isotropy, which characterized each of the surfaces they tested, is directly related to how the crystals align, whether by surface rubbing or by use of ultraviolet rays.

Kumar said their research, funded by the National Science Foundation, is one of many steps to the improvement of liquid crystal technology.

“(This discovery) gives us a way to think of other methods to create means of crystal alignment,” Kumar said.

Kumar sees the discovery as a gateway into the emerging world of liquid crystal technology, though he admits there are discoveries yet to be made.

“There are still questions that need to be quantitatively answered,” he said.

Contact technology reporter Abbey Stirgwolt at [email protected].