February 27, 2006

Magnetic shape shifters

Transforming an object from one shape to another simply by heating it, illuminating it, or exposing it to certain chemicals sounds like an alchemist's dream, but it is a very real and very active area of research for, among other things, making medical devices like stents.

Researchers from GKSS Research Center in Germany and the German Institute for Polymers have expanded the possibilities for shape-memory effect materials with a plastic that changes shape when exposed to magnetic fields. The material can be formed into a permanent shape when hot, then cooled and formed into a different, temporary shape. Once the material is set up this way it can be switched to its permanent state by exposing it to to an alternating magnetic field.

The material contains magnetic nanoparticles that heat up when exposed to an alternating magnetic field. This heats the plastic above the temperature needed relax it into its permanent shape.

This type of material is useful for making medical devices because it is easy to trigger a shape change in the body using a magnetic field.

(Initiation of Shape-Memory Effect by Conductive Heating of Magnetic Nanoparticles in Thermoplastic Polymers, Proceedings of the National Academy Of Sciences, March 7, 2006)

Computing by not computing

Quantum computing is weird enough as it is, given the often counterintuitive nature of quantum physics, but now scientists have demonstrated that it is possible to get an answer from a quantum computer without actually running the computer.

Researchers from the University of Illinois at Urbana-Champaign have applied the paradoxical quantum phenomenon of being able to measure something by not measuring it to a quantum algorithm by not running it.

To do this, the researchers put the quantum computer in a superposition, or mix, of two states: running and not running. From this superposition the researchers were able to glean information about what would have happened had the algorithm executed.

The quantum computer has to be on and configured to run the algorithm, so there is no practical advantage to the technique. It is important, however, because it could sidestep the problem of decoherence -- the destructive effect of noise from the environment that is a major obstacle on the road to practical quantum computers.

(Counterfactual Quantum Computation through Quantum Interrogation, Nature, February 23, 2006)

Bits and pieces

Micro fuel cells get simple

A simple prototype microfluidic fuel cell that does away with the usual membrane between the two electrodes has operated for more than 100 days. The device pave the way for fuel cells for portable devices.

(A Passive Microfluidic Hydrogen-Air Fuel Cell with Exceptional Stability and High Performance, scheduled for publication in Lab on a Chip)

Heart cells pump biochip

A small sheet of heart cells beating in unison serves as the pump for a prototype biochip. The heart cell pump needs no external power source. Biochips make it possible to diagnose diseases and perform medical research using small amounts of samples and without extensive laboratory equipment.

(An Actuated Pump on-Chip Powered by Cultured Cardiomyocytes, scheduled for publication in Lab on a Chip)

Plastic cassette ID's DNA

A small, self-contained plastic cassette amplifies and detects specific types of DNA. The inexpensive, disposable device could be used for rapidly diagnosing diseases in hospitals and clinics.

(A Disposable Microfluidic Cassette for DNA Amplification and Detection, Lab on a Chip, January 2006)

Flat lens focuses microwaves

A left-handed material that bends electromagnetic waves makes an inexpensive microwave lens. The lens, made using printed circuit board manufacturing techniques, could be used for telecommunications, including satellite links.

(Free-Space Microwave Focusing by a Negative-Index Gradient Lens, Applied Physics Letters, February 20, 2006)