Electronics

Silver pen allows electrical circuits to be handwritten on paper and other surfaces

Silver pen allows electrical c...
The silver pen can write electric circuits and interconnects directly on paper and other surfaces (Image: Bok Yeop Ahn)
The silver pen can write electric circuits and interconnects directly on paper and other surfaces (Image: Bok Yeop Ahn)
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A copy of the painting "Sae-Han-Do" by Jung Hee Kim, drawn in conductive ink (Image: Bok Yeop Ahn)
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A copy of the painting "Sae-Han-Do" by Jung Hee Kim, drawn in conductive ink (Image: Bok Yeop Ahn)
Hand-drawn silver ink lines form the interconnects between the flexible array of LEDs mounted on paper (Image: Bok Yeop Ahn)
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Hand-drawn silver ink lines form the interconnects between the flexible array of LEDs mounted on paper (Image: Bok Yeop Ahn)
The silver pen can write electric circuits and interconnects directly on paper and other surfaces (Image: Bok Yeop Ahn)
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The silver pen can write electric circuits and interconnects directly on paper and other surfaces (Image: Bok Yeop Ahn)

People have been using pens to jot down their thoughts for thousands of years but now engineers at the University of Illinois have developed a silver-inked rollerball pen that allows users to jot down electrical circuits and interconnects on paper, wood and other surfaces. Looking just like a regular ballpoint pen, the pen's ink consists of a solution of real silver that dries to leave electrically conductive silver pathways. These pathways maintain their conductivity through multiple bends and folds of the paper, enabling users to personally fabricate low-cost, flexible and disposable electronic devices.

While metallic inks have been used to manufacture electronic devices using inkjet printing technology, the silver pen offers users the freedom and flexibility to construct electronic devices on the fly, says Jennifer Lewis, the Hans Thurnauer professor of materials science and engineering at the University of Illinois who led the research team along with Jennifer Bernhard, a professor of electrical and computer engineering.

"The key advantage of the pen is that the costly printers and printheads typically required for inkjet or other printing approaches are replaced with an inexpensive, hand-held writing tool," said Lewis. "This is an important step toward enabling desktop manufacturing (or personal fabrication) using very low cost, ubiquitous printing tools."

Hand-drawn silver ink lines form the interconnects between the flexible array of LEDs mounted on paper (Image: Bok Yeop Ahn)
Hand-drawn silver ink lines form the interconnects between the flexible array of LEDs mounted on paper (Image: Bok Yeop Ahn)

The researchers have used the pen to create a flexible LED display on paper, conductive text and three-dimensional radio-frequency antennas. They now plan to expand the palette of inks to enable pen-on-paper writing of other electronic and ionically conductive materials.

While the pen is likely to prove attractive to electrical engineers and hobbyists, the researchers have also highlighted the potential of the device for creating art. Using the pen to sketch a copy of the painting "Sae-Han-Do" by Jung Hee Kim, which portrays a house, trees and Chinese text, the researchers used the ink as wiring for an LED mounted on the roof of the house that was powered by a five-volt battery connected to the edge of the painting.

A copy of the painting "Sae-Han-Do" by Jung Hee Kim, drawn in conductive ink (Image: Bok Yeop Ahn)
A copy of the painting "Sae-Han-Do" by Jung Hee Kim, drawn in conductive ink (Image: Bok Yeop Ahn)

The University of Illinois team's research appears in the journal Advanced Materials.

14 comments
Jeff Katz
This is nothing new. Conductive pens have been around for a long time, ostensibly to replace damaged traces on regular PCBs. I don\'t see how this pen is any different.
Filipe Varela
Where do i order?
Austin Brown
Jeff, that is to repair damaged PCBs, and could be used on paper. But, if the ink your talking about is put on paper, and bent, will its conductivity sustain itself? will the electronic pathway still be intact?
Charles Bosse
What kind of solvent does this use? In the past, effective silver \"ink\" has come in pretty toxic solutions.
Facebook User
@Austin: Yes it will. There are cheap pens at Farnell (Newark Direct) (cheap being 10 to 15 euro) that will leave a semi-hard substrate that may tear in tight corners (though slight flexibility is there). But there are chemical suppliers that have been selling these kinds of gel-based carbon-silver hybrid pens for over 10 years at twice or three times the cost, but these will stay in tact around very tight corners and work perfectly fine on paper, even the more porous sketching paper. That said, this being a normal kind of gel-ball-point I would be interested in sampling it to compare, because there is certainly room for improvement in the ergonomics department.
Marco Righetto
Is it on the market?
Bobby Lee
Austin, yes it will. The pens put out by Caig use silver in an epoxy so it flexes just fine without breaking the circuit.
Ken Gilleo
Circuit writing is very, very old and silver has been a common material because of it\'s unique properties. I had a silver ink pen at one time. Thomas Edison, in 1904, proposed applying silver traces to linen cloth to make flexible circuits and this is documented in a letter. Tom suggested using a silver salt solution and then reducing to pure silver once applied.
Gregg Eshelman
How do you do circuits where one trace has to cross over but not connect to another?
Ronald Grover
Gregg, Try a piece of tape.