Microscopic structures that use light in metals to relay information could improve the speed of wireless technology and enable the printing of magnetic materials. Electrical engineers at the University of Utah, using an inkjet printer, developed a new technique that controls electrical conductivity within such microstructures. This could rapidly produce superfast components in electronic devices, according to the researchers. Using an inexpensive printer and two color cartridges (one silver and one carbon), the team printed 10 different plasmonic structures with a periodic array of 2,500 holes of different sizes and spacing on a 2.5-in.2 plastic sheet. Until now, expensive equipment has been necessary to create plasmonic arrays, and has only been able to manufacture one array at a time. The arrays tested had holes 450 µm in diameter and spaced 1/25-in. apart. Depending on the relative amounts of ink used, the plasmonic array’s electrical conductivity could be controlled. “We can draw and print these structures exactly as we want them,” said study leader Ajay Nahata, a professor of electrical and computer engineering at the university. “We have an extra level of control over both the transmission of light and electrical conductivity in these devices. Our technique lets you make rapid changes to the plasmonic properties of the metal without the million-dollar instrumentation typically used to fabricate these structures.” The researchers also used terahertz imaging to measure the effect of printed plasmonic arrays on a beam of light, which, when directed at a periodic array of holes in a metal layer such as silver or gold, results in resonance. While only two were used here, the researchers said that depending on the application, as many as four different inks in a four-color inkjet printer could be used. The study was funded by the National Science Foundation through the University of Utah’s Materials Research Science and Engineering Center. The work is published in Advanced Optical Materials. For more information, visit: www.utah.edu.