Swimming in A Pool of Atoms and Molecules

For microscopic swimmers, near atomic levels, paddling is difficult because at such tiny lengths, water seems to be as thick as honey. Imagine if you will, swimming in a pool packed full of small beach balls instead of water. Not only would swimming be a difficult task, the simple action of moving from one of the pool to the other would require an enormous amount of effort and be very difficult due to the "viscosity' of the beach balls through which you were moving.

In an attempt to circumnavigate this viscosity, scientists from the University of Sheffield in England and their fellow colleagues have managed to develop plastic swimmers without any moving parts. The elimination of external "appendages", though they tend to aid in the movement of some objects through fluids, also add to the resistance experienced by the main body. They began their experiment by coating 1.6-micron-wide balls on one side with a very thin layer of platinum and then placed them in a solution comprised of hydrogen peroxide and water. The platinum metal catalyzes the breakdown of hydrogen peroxide into oxygen and water, which in turn propels the balls at speeds of up to five microns per second through the solution. To further show relationship, this is half as fast as comparably sized bacteria move. After a few seconds, though, the balls begin to get crowded and push around the surrounding atoms and molecules and finally begin to wander aimlessly.

The scientists propose that magnetic fields might help guide the swimmers and contribute to longer paths of purpose. They also suggest they might be able to adapt them for guided work in fluids such as blood, to help deliver drugs within the body.