Implanted pacemakers and defibrillators have to be replaced when their built-in power sources run low – normally every 7 to 10 years – and any surgery carries some risk for patients. So David Tran and colleagues at Stanford University, California, US, say it would be better for the devices to harvest their own power from the human body. The team has come up with a number of designs which generate power by virtue of being attached to the outside of the heart. This causes, for example, a magnet to move through a coil, or a piezoelectric element to move, in a way that generates current. The team says this could make implantable devices self-powering, or at the very least, increase the periods between replacements. Read the full self-powering implants patent application. Plasma-coated landing gear The quest for quieter aircraft has spurred the development of quieter engines. But one of the primary sources of noise during take off and landing is the airflow around the landing gear. Airflow is quietest when it flows smoothly around an object and sticks closely to its shape. But landing gear prevents this and causes the flow to separate from the surface of the aircraft, causing turbulence and noise. Now Thomas Flint at the University of Notre Dame in Indiana says it may be possible to encourage smoother flow by creating a plasma around the landing gear while it is down. This is done generating a powerful electric field to ionise the air nearby. The plasma acts as a kind of buffer for the airflow, encouraging it to move around the gear more smoothly, thereby reducing noise, says Flint. Read the full plasma noise reduction patent application. Magnetic ''gecko'' grip Many scientists have been inspired by the gecko''s ability to walk effortlessly across walls and ceilings.
In recent years, researchers have discovered that gecko feet are covered with tiny hairs that stick to almost any surface using weak van der Waals forces between molecules. Although each hair sticks only weakly, many tens of thousands of them create a force strong enough to support the gecko''s weight. The gecko is able to release its feet by peeling the hairs away from the surface at an appropriate angle, which is far easier than attempting to yank them all away in one go. A number of teams have attempted to copy the gecko''s foot with poor results, say Kimberly Turner and Michael Northern at the University of California Santa Barbara, US. The problem is that artificial gecko feet lack the lizard''s ability to force the hairs into contact with an uneven surface and peel them way again with their toes. Now Turner and Northern have attached polymer nanohairs to nickel pads, which are part of a microscopic mechanism that can force the pads towards or away from a surface using a magnetic field. The researchers say this technique can mimic the action of geckos'' toes and has worked well in tests. The result is a mechanical adhesive pad that can be switched on and off. The principle could be used for anything from window-cleaning robots to mark-free picture hangers.