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Not Quite A Submarine, Researcher Finds Way To Move Tiny Device Through Bloodstream

Sung Kwon Cho

In the 1966 movie The Fantastic Voyage, a team of scientists were shrunk to microscopic proportions and sent inside the human body. Now, researchers at the University of Pittsburgh are taking that idea into the 21st Century -- sort of. 

Pitt mechanical engineering associate professor Sung Kwon Cho hasn't figured out how to shrink a submarine, but he has figured out how to control the movement of a tiny device through a simulated blood stream using nothing more than an air bubble and an ultrasound machine.

“We have a small bubble and then we apply the sound wave and then this bubble oscillates and then generates a flow around it,” Cho said.

Sung came upon the idea while he was working with very small bubbles and sound waves for another project. He noticed that when he applied sound waves of just the right frequency to a bubble trapped in a tube it would begin to oscillate. That oscillation caused the fluid around it to flow in a consistent direction.

Sung’s team created a chip about the diameter of a human hair with a void or a tube on one side. When that chip was placed in a fluid, it automatically captured a small air bubble roughly 80 nanometers in length, or about the size of a dozen red blood cells. Once the length of the bubble was measured, Sung could calculate the frequency of the sound wave needed to make the bubble pulse within the void.  That oscillation pushed water out of the tube and propelled the chip forward.

“Of course that was exciting, really exciting,” Cho said.

But the swimmer was only able to move in one direction, so researchers created a chip with different sized tubes on different sides of the device. Depending on which sound frequency is applied, the tubes on one side or another are activated and the chip can be “driven” in two directions.

“Our next step is to try to navigate in the three-dimensional plain, three dimensional spaces,” Cho said.

In theory, the device could be injected into a human and controlled using a hand held ultra sound device like the one an OB/GYN might use on an expectant mother. That same device could also be used to watch it’s progress. Sung says a fleet of these "swimmers" could be coated with a drug and delivered to a hard-to-reach part of the body.

Those swimmers could then dissolve and be eliminated by the body. 

Among the obstacles to overcome before the swimmers could be injected into a human is increasing the speed of the devices. In a simulated blood vessel they can move at a few centimeters per second but compared to some parts of a circulatory system that's not fast enough to swim upstream.

Sung is working with other engineers and researchers at the University of Pittsburgh Medical Center to forward his experiments. Until then, The Fantastic Voyage is still something limited to the silver screen.

In this week's Tech Headlines:

  • Artificial intelligence developed by two Carnegie Mellon University computer science students was able to outplay humans in the classic computer game Doom. It even beat the game's computer player. The work flows from Google's DeepMind experiment where a machine beat a human in an old Atari video game. The programmers said not only is their computer player a good shot, it has also learned to dodge shots. 
  • Forget about self-driving cars, experimenters are turning their eyes to the skies. A single-engine Cessna Caravan that took off from a small airport in Virginia on Monday had a robot at the controls. Unlike self-driving cars that have the computer applying breaks and steering, the plane was being flown by a robot with spindly metal tubes and rods for arms and legs and a claw hand grasping the throttle. The demonstration was part of a government and industry collaboration attempting to replace the second human pilot in two-person flight crews with robot co-pilots that never tire, get bored, feel stressed out or become distracted.  The program, known as Aircrew Labor In-Cockpit Automation System or ALIAS, is funded by the Defense Advanced Research Projects Agency and run by Aurora Flight Sciences.
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