4 ms·

Researchers create rollerball-pen ink to draw circuits

46 points by ph0rque 15y ago

hammmatt 15y ago
This seems awesome. They neglect to mention how to power any circuits and what components you could and how. If this could be perfected though, Electrical Engineers would slowly take over the world... with circuits....
- andrewflnr 15y ago
  They already did.
  - hammmatt 15y ago
    :) It's nice to hear we are appreciated.
jws 15y ago
It appears to handle reasonable amounts of current, it can drive an LED over about 10" of trace in the LED grid example. That example also has cross overs, though they don't mention it in the article. I wonder how they bond the components to the traces. Is setting them on fresh ink sufficient?
- delinka 15y ago
  Binding components to the traces (or even keeping them on the paper) is definitely my biggest area of curiosity. Putting a lil-dab-o-glue on the bottom would certainly be problematic as it would spread to insulate the connections. Components with adhesive surfaces would solve the problem of sticking it to the paper but not the problem of binding to the trace path. I have no ideas how that would work.
- ajdecon 15y ago
  I used to work in the lab in question, though nowhere near this project. (And I'm ridiculously proud of my colleagues right now. :D ) To answer your question, setting the components on fresh ink is often sufficient but not always. IIRC, components were often put in place and then "drawn over" a second time with the pen, or small beads of ink were put in place. I saw cross-overs demonstrated simply using normal white-out (!) after the first trace was dry, but I no longer have access to a journal subscription so I'll have to bug my colleagues for a copy before I know if that is what was used in the publication.
- gcb 15y ago
  use other side of paper? tape one piece of paper over the other line?
NonEUCitizen 15y ago
Conductive pens are already available and used for circuit board repair (I think resistance is too high for long traces), e.g.: http://www.circuitspecialists.com/8420-p.html If you check the PCB forums, people are always toying with the idea of hooking these up to a plotter for DIY circuit boards without needing etching chemicals. Presumably these researchers have come up with a better one (probably more consistent flow).
- delinka 15y ago
  Seems many people are jumping on the "been doing it for years" bandwagon. Since I've never touched this stuff, I have questions: do the existing conductive pens work on paper? Can you take notebook or drafting paper, apply the existing conductive pen "ink" and get a functional circuit of reasonable size (up to the size of the paper) without burning up the paper? You mention that perhaps the resistance is currently too high and that these guys may have come up with something that has "more consistent flow." The news here is ink-on-paper makes circuits, not conductive pens have been invented for the first time.
  - AretNCarlsen 15y ago
    The existing pens are intended only for minor PCB repairs. They are terribly expensive, as in $100/oz, have high resistance, and cannot be drawn with smoothly (like a pen). They are also not intended for the kind of flexing that you see on a piece of paper. Example (0.3oz for $30): http://www.amazon.com/gp/aw/d/B000B5YDT8 http://www.amazon.com/gp/aw/d/B000B5YDT8 Historically, you've been better off using conductive silver thread for flexible and on-the-fly circuits. Still expensive and resistive, but tolerably so. Example (82 ohms/ft, $5/yd): http://www.sparkfun.com/products/8544 http://www.sparkfun.com/products/8544
    - sorbus 15y ago
      They can be found for around $30/oz; the first google shopping result for "conductive pen" is 9 grams (0.317 oz) for ~$10. It seems to be the same one you linked to on amazon (is that the mobile version, by the way? Because there's practically no information on that page and it looks horrible).
regomodo 15y ago
This has given me an idea: an etch resist pen in a plotter-like setup. It's about time I use the steppers i pulled out of old Epson printer and use up some of my copper-clad boards.
deleted 15y ago
[deleted]
andrewflnr 15y ago
Great, now they just need to stock compatible napkins in bars. "hey, I've got this idea... Look, it works!"
- NonEUCitizen 15y ago
  Always carry a few LEDs and resistors in your pocket!
sn 15y ago
There's already the paper-based mobius circuit: http://www.evilmadscientist.com/article.php/mobiuscircuit http://www.evilmadscientist.com/article.php/mobiuscircuit
ChuckMcM 15y ago
This struck me as non-novel since the CircuitWorks pens have been around for a while. But the ability to write on a flexible medium and bend it etc is the news here. There are a number of uses for something like this, if its economical. I hope they can commercialize it.
- gcb 15y ago
  Nothing that couldn't be done with 30's era conductive paint. granted you have to use a small brush to apply... ...and i still think "soldering" leds to a piece of paper is ... wrong.

46 points by ph0rque 15y ago

This seems awesome. They neglect to mention how to power any circuits and what components you could and how. If this could be perfected though, Electrical Engineers would slowly take over the world... with circuits....

andrewflnr 15y ago
They already did.
- hammmatt 15y ago
  :) It's nice to hear we are appreciated.

jws 15y ago

It appears to handle reasonable amounts of current, it can drive an LED over about 10" of trace in the LED grid example. That example also has cross overs, though they don't mention it in the article. I wonder how they bond the components to the traces. Is setting them on fresh ink sufficient?

delinka 15y ago
Binding components to the traces (or even keeping them on the paper) is definitely my biggest area of curiosity. Putting a lil-dab-o-glue on the bottom would certainly be problematic as it would spread to insulate the connections. Components with adhesive surfaces would solve the problem of sticking it to the paper but not the problem of binding to the trace path. I have no ideas how that would work.
ajdecon 15y ago
I used to work in the lab in question, though nowhere near this project. (And I'm ridiculously proud of my colleagues right now. :D ) To answer your question, setting the components on fresh ink is often sufficient but not always. IIRC, components were often put in place and then "drawn over" a second time with the pen, or small beads of ink were put in place. I saw cross-overs demonstrated simply using normal white-out (!) after the first trace was dry, but I no longer have access to a journal subscription so I'll have to bug my colleagues for a copy before I know if that is what was used in the publication.
gcb 15y ago
use other side of paper? tape one piece of paper over the other line?

NonEUCitizen 15y ago

Conductive pens are already available and used for circuit board repair (I think resistance is too high for long traces), e.g.: http://www.circuitspecialists.com/8420-p.html If you check the PCB forums, people are always toying with the idea of hooking these up to a plotter for DIY circuit boards without needing etching chemicals. Presumably these researchers have come up with a better one (probably more consistent flow).

delinka 15y ago
Seems many people are jumping on the "been doing it for years" bandwagon. Since I've never touched this stuff, I have questions: do the existing conductive pens work on paper? Can you take notebook or drafting paper, apply the existing conductive pen "ink" and get a functional circuit of reasonable size (up to the size of the paper) without burning up the paper? You mention that perhaps the resistance is currently too high and that these guys may have come up with something that has "more consistent flow." The news here is ink-on-paper makes circuits, not conductive pens have been invented for the first time.
- AretNCarlsen 15y ago
  The existing pens are intended only for minor PCB repairs. They are terribly expensive, as in $100/oz, have high resistance, and cannot be drawn with smoothly (like a pen). They are also not intended for the kind of flexing that you see on a piece of paper. Example (0.3oz for $30): http://www.amazon.com/gp/aw/d/B000B5YDT8 http://www.amazon.com/gp/aw/d/B000B5YDT8 Historically, you've been better off using conductive silver thread for flexible and on-the-fly circuits. Still expensive and resistive, but tolerably so. Example (82 ohms/ft, $5/yd): http://www.sparkfun.com/products/8544 http://www.sparkfun.com/products/8544
  - sorbus 15y ago
    They can be found for around $30/oz; the first google shopping result for "conductive pen" is 9 grams (0.317 oz) for ~$10. It seems to be the same one you linked to on amazon (is that the mobile version, by the way? Because there's practically no information on that page and it looks horrible).

regomodo 15y ago

This has given me an idea: an etch resist pen in a plotter-like setup. It's about time I use the steppers i pulled out of old Epson printer and use up some of my copper-clad boards.

deleted 15y ago

[deleted]

andrewflnr 15y ago

Great, now they just need to stock compatible napkins in bars. "hey, I've got this idea... Look, it works!"

NonEUCitizen 15y ago
Always carry a few LEDs and resistors in your pocket!

sn 15y ago

There's already the paper-based mobius circuit: http://www.evilmadscientist.com/article.php/mobiuscircuit http://www.evilmadscientist.com/article.php/mobiuscircuit

ChuckMcM 15y ago

This struck me as non-novel since the CircuitWorks pens have been around for a while. But the ability to write on a flexible medium and bend it etc is the news here. There are a number of uses for something like this, if its economical. I hope they can commercialize it.

gcb 15y ago
Nothing that couldn't be done with 30's era conductive paint. granted you have to use a small brush to apply... ...and i still think "soldering" leds to a piece of paper is ... wrong.