From The New York Times:
Hot Off the Presses, Conductive Ink
Circuits made with ink that can withstand the rigors of pressure, heat
and moisture are replacing copper wire and bulky connections in new
Hot Off the Presses, Conductive Ink
By ANNE EISENBERG
INK is an age-old medium, yet it’s keeping up with changing times. It’s long been used in pens, of course, and more recently in printer cartridges, but now it’s also being mixed to print lightweight circuits, sensors and switches.
Circuits made with conductive inks that can withstand the rigors of pressure, heat and moisture are replacing copper wire and bulky connections in many new products. The ink circuits, typically made with a range of conductive materials, are printed on surfaces like plastic, cloth and paper.
One company, T-Ink, has developed inks so robust that circuits, sensors and switches can be printed on flat plastic and then molded into three-dimensional components that control overhead lights and sunroofs in cars. The surface of the control panel is touch-sensitive, so just a tap can turn the lights on. And the process is potentially less costly than current methods.
“This is a highly imaginative use of printed electronics,” said Harry Igbenehi, a technology analyst who follows printed electronics at IDTechEx, a consulting company in Cambridge, England.
Parts made with this technology can replace thicker assemblies, he said, reducing the weight and dimensions of wired components.
Printed electronics in cars are not new — they have long been used, for example, in windshield defrosters. “But the technology has grown increasingly sophisticated,” Dr. Igbenehi said. “It’s been a quiet revolution.”
T-Ink’s printed wiring, switches and sensors for its automotive panels require unusual ink properties, said John Gentile, founder and co-chief creative officer of the company, which is based in Manhattan.
The ink circuit must be soft enough to stretch during formation and tough enough to withstand the intense pressure and heat of the molding process.
“The ink has to be very hard when you shoot 500-degree molten plastic all around it to make a solid piece,” Mr. Gentile said. “It can’t delaminate when you put it in the molten plastic.”
The first of the company’s molded panels for automobiles will be shipped in September, he said, and he foresees that they will be used in 1.2 million cars next year.
T-Ink also makes stretchable, washable circuits printed on cloth that measure heart rate, respiration and other biometrics for sports clothing and medical applications like electrocardiogram vests. Next year, sleeping bags made with the company’s technology will have circuits printed at the foot of the bag to warm cold toes without the stiff cords of electric blankets or the ridges of conductive thread, Mr. Gentile said.
For textile uses, the circuits can be printed directly onto fabric. They can also be printed on a paper sheet with glue on one side and transferred to the fabric in a heat press. “Count to 10, peel off the paper, and that piece of material has the circuits, sensors, buttons and switches,” Mr. Gentile said.
T-Ink — for “thinking ink” — was formed in 2001. It initially produced novelty and promotional items like toys, interactive place mats and T-shirts. (The shirts might produce different sounds when touched at different places.) The company is maintaining many of its original products even as it moves into new areas with its molding process for control panels, said Andrew Ferber, T-Ink co-chairman.
T-Ink circuits can be printed via standard press techniques. Often, the circuits are made of many layers of conductive and nonconductive inks, said Peter Harrop, chairman of IDTechEx. When T-Ink employees make these multilayered electronics, he said, “they build up the ink in layers — I call the process plywood electronics.”
NOVALIA, a small company in Cambridge, England, designs interactive products printed with conductive ink, concentrating on making the print interactive by touch, said Kate Stone, founder and managing director. The inks are printed by conventional methods like offset.
The company has demonstrated interactive, talking paper posters that people can touch as they would the screen of an iPhone or iPad. One prototype poster asks people their preferences for a perfect cake. Once users decide on the frosting and other details, tapping the poster for each choice, they are directed to a Novalia Facebook page that shows descriptions and images of the recommended cakes. In the future, other companies could link their Web sites to such posters.
Another prototype poster connects wirelessly to an iPad within about 15 feet. If you touch the poster to choose different song clips, the music can be heard on the iPad.
Dr. Stone says that paper, like ink, has an electronic future. “Paper can be much more interactive,” she said.