STATE COLLEGE, Pa., May 11 (UPI) -- U.S. scientists say they've created tunable fluidic micro lenses that can focus light at will while remaining stationary and can be fabricated on a chip.

The Pennsylvania State University research engineers said such fluidic lenses can be used for many applications, such as counting cells, evaluating molecules or creating on-chip optical tweezers. The lenses might also provide imaging in medical devices, eliminating the necessity of moving the tip of a probe, they added.

The researchers, led by Assistant Professor Tony Jun Huang, said conventional, fixed focal length lenses can focus light at only one distance and the entire lens must move to focus on an object or to change the direction of the light. Fluidic lenses, however, can change focal length or direction in less than a second while remaining in the same place.

"We use water and a calcium chloride solution because they are readily available and safe and their optical properties have been well characterized," said Huang.

The research that included graduate students Sz-Chin Lin, Michael Lapsley, Jinjie Shi, Bala Juluri and Xiaole Mao was reported in a recent issue of the journal Lab on a Chip.