Week of August 15, 2005

Your face on my cellphone

The widespread availability of digital photography thanks to camera-equipped cellphones opens the door to all manner of humor and hijinks. Aiding and abetting wouldbe digital jokesters is software that allows users to transform photographs of faces into animated 3D models.

The software, developed by researchers from Ericsson subsidiary Ericsson Nikola Tesla, Kate-Kom d.o.o. and Zagreb University in Croatia, allows people to send each other short animated clips featuring talking heads complete with audio messages produced with speech synthesis technology. For example, you could take a friend's picture, convert the image of his face into a 3D model, type in embarrassing or humorous phrases, and send the resulting animation clip to his girlfriend. This type of image capture and animation technology has been around for years in laboratories. The researchers fit the software on cellphones and created an easy-to-use interface.

(LiveMail: Personalized Avatars for Mobile Entertainment, presented at Mobile Systems, Applications and Services (MobiSys) 2005, Seattle, Washington, June 6-8, 2005)

All plastic radio ID tags

One of the promises -- and perils -- of radio frequency identification (RFID) tags is that when the chips can be made cheaply enough, anyone, including manufacturers and governments will be able to tag, and therefore track, everything under the sun.

Key to making them cheaply is making them entirely of plastic. Researchers from Belgian microelectronics research laboratory IMEC and the Catholic University at Leuven in Belgium have built a high-speed organic diode that could be the last piece of the puzzle.

RFID tags don't require a power source. They are activated when a tag reader hits them with radiowaves; the radiowaves provide the power the tags need to transmit a signal back to the reader. Plastic transistors are fast enough to carry out the task of transmitting a tag's ID codes, but the rectifier, which converts alternating current produced by the reader's radio signal to the direct current needed by the tag's circuits, is another matter. The researchers' organic diode rectifier -- at 50 megahertz -- is fast enough to do so.

(50 MHz rectifier based on an organic diode, Nature Materials, August, 2005)

DNA and electricity

The question of whether or not DNA molecules conduct electricity has been the subject of a hot debate stoked by conflicting experimental results. The tricky part of answering the question is it's extremely difficult to connect individual molecules to circuit testers. Because of this, past results have been all over the map.

Researchers from Hebrew University and the Weizmann Institute of science in Israel have developed a more accurate test that shows that DNA does conduct electricity. Key to the accuracy was a way to make the DNA molecules stand up so that only one end was touching the surface, assuring that nothing was interfering with or assisting the molecules' conductance. The physics of how electricity moves through DNA remains an open question.

(Direct measurement of electrical transport through single DNA molecules of complex sequence, Proceedings of the National Academy Of Sciences, August 16, 2005)

Simpler nanotube circuits

Carbon nanotubes are the object of many a researcher's vision for ultra miniaturized computer circuits. Among the many challenges to making computer chips from nanotubes, however, has been finding a way to connect millions of closely-packed nanotubes to metal electrodes to form transistors.

Researchers from the University of California at San Diego and Clemson University have sidestepped the problem by showing that Y-shaped carbon nanotubes act as electrical switches all by themselves, removing the need for the connections. Given a high enough voltage, the Y-shaped nanotube blocks electrical current to turn the switch off. The researchers are still working out the physics involved in the switching process.

(Novel electrical switching behavior and logic in carbon nanotube Y-junctions, Nature Materials, August 14, 2005)