Flexible printed electronics and solar-cell arrays promise to be cheaper and more versatile than their rigid counterparts. But their components still need to be linked by tiny metal electrodes in order to get electrons flowing through a device. A new silver-nanoparticle ink could be just the thing for printing high-performance electrical connections for flexible devices.
The ink is the first that can be printed out of plane–that is, it can be printed from a stylus that moves in three dimensions rather than just two. Other nanoparticle inks are slow setting and compatible only with ink-jet or screen printing methods, which require several passes in order to make even a thin electrode. The new fast-setting ink, made by Jennifer A. Lewis, a professor of materials science and engineering at the University of Illinois at Urbana-Champaign, is described online in the journal Science.
Lewis’s ink consists of a water solution that’s 75 percent silver nanoparticles by weight. Because of the high proportion of silver, the ink flows readily through a nozzle and sets quickly once it’s exposed to a flash of heat. The ink can be used to make silver wires that are only about two micrometers in diameter. These microelectrodes can be repeatedly stretched and flexed without any degradation of their electrical performance. The Illinois researchers printed a wire on a stretched-out spring, then repeatedly stressed the spring, but the wire still conducted electricity just as well as before. They also used the ink to print microelectrodes for solar-cell and LED arrays.
Lewis says that her research team is now working on improving two of the inks’ properties. First, they want to design silver inks that set at lower temperatures. Today, the ink must be heated to between 200 and 250 °C, an amount of heat that would melt the polymers used in many flexible electronic devices. Lewis would like to bring this temperature range down by about 100 degrees. Second, the current technique is simply too slow for large-scale manufacturing: the new inks can be printed at a speed of one millimeter per second. So Lewis says that she’ll need to develop inks that can be printed two orders of magnitude faster.
Below is a video of the printing process sped up to twice the actual speed.
Video credit: AAAS/Science
A horrifying new AI app swaps women into porn videos with a click
Deepfake researchers have long feared the day this would arrive.
We can’t afford to stop solar geoengineering research
It is the wrong time to take this strategy for combating climate change off the table.
Meet Altos Labs, Silicon Valley’s latest wild bet on living forever
Funders of a deep-pocketed new "rejuvenation" startup are said to include Jeff Bezos and Yuri Milner.
The new version of GPT-3 is much better behaved (and should be less toxic)
OpenAI has trained its flagship language model to follow instructions, making it spit out less unwanted text—but there's still a way to go.
Get the latest updates from
MIT Technology Review
Discover special offers, top stories, upcoming events, and more.