LEDs produce light when incoming negatively charged electrons and positively charged "holes" attract each other and combine. The electrons and holes have a physical property called "spin" that rotates like the Earth rotating on its axis, but unlike the Earth they can spin in different directions. Physicists once believed that only 25% of the energy flowing into an LED could be emitted as light. Valy Vardeny, the physics chairman at the University of Utah, developed a test that indicates that 41 to 63% of the energy flowing into an LED can be converted to light using plastic LEDs made from organic materials called electrically conducting polymers and oligomers. Vardeny bombarded ten different plastics with microwaves, and found that materials that emit red and blue violet light emitted more light when placed in a magnetic field at cold temperatures. "The findings mean it should be possible to make more efficient light emitters for lasers, displays, and computer and television screens," says Vardeny. For more information, contact the University of Utah, Salt Lake City, UT 84112-9017; FAX: (801) 585-3350.
Producing high-quality end-production metal parts with additive manufacturing for applications like aerospace and medical requires very tightly controlled processes and materials. New standards and guidelines for machines and processes, materials, and printed parts are underway from bodies such as ASTM International.
Engineers at the University of San Diego’s Jacobs School of Engineering have designed biobatteries on commercial tattoo paper, with an anode and cathode screen-printed on and modified to harvest energy from lactate in a person’s sweat.
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