Light Transport

Generations of Star Trek fans grew up watching the transporter system on the starship Enterprise beam crew members from ship to planet surface and back again. Quick as a beam of light they winked in and out from place to place. Modern medical researchers are not yet ready to beam up Scotty and his pals, but they are looking at beams of light as a propulsion system.

Scientists would like to use ultra small nano-scale tubes to push tiny amounts of drugs dissolved in water to exactly where they are needed in the human body. The roadblock has been the challenge of building pumps small enough to do the job. The engineering challenge of building a nano-scale pump is tough enough. But there are other complications. Biological molecules can clog valves small enough to fit inside a channel the size of bacteria.

Scientists at Arizona State University have a solution. They created a system that does not rely on mechanical parts. The ASU researchers developed a technique to pull water up a tube tinier than a straw by shining a beam of light on the surface of the tube. The process is called photocapillarity. The process might be useful in future nanotechnology applications, such as the targeted distribution of medicine in the body.

“As the size of capillaries or channels in devices shrinks, it becomes very difficult to control the movement of ‘liquid,’” says Antonio Garcia, an ASU bioengineering professor. “The everyday use of mechanical valves and pumps becomes difficult in nanotechnology because making them tinier is a manufacturing challenge. Also, any real-life application would be prone to operational problems, such as clogging of the pump or valve by tiny molecules.”

Garcia works with Devens Gust and Mark Hayes, professors in the department of chemistry and biochemistry. While studying light responsive molecules, they found a way of attaching the molecules to the surface and structuring the surrounding surface to control the spread of water.

“When we shine light just beyond the visible range, the light responsive molecules attract water and trigger the advancement of water through the channel,” Garcia explains.

The ASU team also developed science lab demonstration kit. By the end of the year, students and teachers can order inexpensive glass tubes and a laboratory guide to exploring the phenomena.

“By providing the lab kit, we hope to stimulate the creativity of the next generation of scientists and engineers. They will be the ones who routinely design new products using nanotechnology,” Garcia says.