How a $60 Inkjet Printer Can Create Super-Fast Conductors

Forget 3D printing—making quick, cheap, and super-fast electronics could be done by using a normal inkjet printer with silver and carbon ink in its cartridge and printing onto a plastic sheet. It’s a really simple solution to the dilemma of how you can get faster and faster data transmission in ever-smaller sizes through the marriage of plasmonics with terahertz, or “t-ray,” tech.

Plasmonics is supposed to be the best of both optical fiber and electronic componants. By using light to create density waves of free electrons in a metal, you can get the high bandwidth of optical data transfer across metal wire that can be tinier than bulkier optical tubing. One problem holding plasmonics back has been getting the conductivity just right. The way plasmonic materials are created today takes both a long time and really expensive equipment.

But a study published today in the journal Advanced Optical Materials outlines how researchers at the University of Utah have created the microscopic structures with a $60 inkjet printer with enough precision to control the amount of conductivity, bringing wireless devices that operate 1,000 times faster than Bluetooth that much closer to reality.

One of the printer’s cartridges was filled with conductive silver ink and the second cartridge was filled with resistive carbon ink. Then computer-generated drawings of plasmonic structures were printed onto plastic sheets with each dot having a specific amount of each ink—the silver functioned as the conductor and the carbon as the dielectric. The researchers then sent terahertz-frequency light, which is between the microwave and infrared parts of the light spectrum through the arrays of dots. By varying the amount of carbon and silver in each dot, they could control the conductivity and efficiency of the current.

Ajay Nahata, senior author of the study, told Nanowerk that the new printing technique gives them “an extra level of control over both the transmission of light and electrical conductivity.”

"Because we can draw and print these structures exactly as we want them, 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," Nahata said.

The four arrays that the researchers printed and tested had holes that were 450 microns in diameter, or four times the width of a human hair, and spaced 1/25th of an inch apart. By altering the relative amounts of silver and carbon ink, the researchers could control the plasmonic array's electrical conductivity, or the efficiency of how the array carried an electrical current.

Plasmonics have yet to prove terribly practical, as the wave of electrons tends to dissipate after a really short distance, like millimeters. Terahertz-based wi-fi suffers from a similiar problem, albeit on a wi-fi scale. The Japanese electronics supplier ROHM set the wireless data transmission speed of 1.5 gigabits per second, but terahertz wi-fi would probably only have a range of about 10 meters.