One of the projects at the recent Hacker Hotel hacker camp in the Netherlands appeared to have achieved the impossible. A vertical PCB surface was holding pieces of paper as though they were pinned to it as on a notice board, yet there was no adhesive or fixings in sight. Was Harry Potter among the attendees, ready with a crafty bit of magic at a waggle of a wizard’s wand, or was a clever hack at work?
Of course, it was the latter, as [Jana Marie Hemsing], had created an electrostatic adhesion plate because she was curious about the phenomenon. A PCB with extra insulation has an array of conductors on one side that carry a very high voltage. High enough for electrostatic attraction to secure a piece of paper to the PCB.
The voltage is generated from an AC source by a Cockroft-Walton multiplier on the back of the PCB, and the front is coated with Plasti-Dip for insulation. It seems that soldermask is not a reliable insulator at such high voltages.
Using the board, [Jana] was able to attach a piece of paper to it with a shearing force of 5 mN at 3 kV applied voltage, which may not sound like much but appeared to be just enough to carefully pick the contraption up by the piece of paper. The boards are designed for tessellation, so larger arrays could easily be assembled.
We’ve never had a project quite like this one, but we have brought you an electrostatic ping-pong ball accelerator.
That brings back memories. HP had a plotter that used electrostatic adhesion back in the early or mid 70’s. I was always fascinated by it. I really wanted to take one of them apart in fact. Over the years I have dissected many plotters but never one of those HP’s. I suspect you pretty much nailed what was going on behind the scenes.
There’s a teardown of that HP plotter here:
http://www.kerrywong.com/2017/04/30/hp-7044a-x-y-recorder-teardown-lorenz-attractor/
Quite amazing the designers decided to use a high voltage power supply instead of some mechanical clamps.
Thank you! I am checking it out now. Memories…
Used on a number of plotter models. Still have a 7225A that uses it. There was also an auto feed model that used it.
Also Roland used that principle in the ’80s on their tilted plotters. I think it was DXY does our something. It was really convenient to place the paper, push a button and then it would stick in place
I have a vintage plotter with electrostatic grip for the paper. Opened it once, it’s all analog, including the controls and the positioning feedback loops and sensors.
https://cdn.hackaday.io/images/7994761552207999701.jpg
Will restore it one day
:o)
That’s probably a re-badged HP such as the once mentioned above. Almost all Wang peripherals were re-badges of ‘named brand’ types.
Was just about to comment the same lol. I converted one in to a glass engraver and it held thin glass sheets too
Chart recorders I think predate plotters, and used static paper grip, they were common in skips when PC logging became a thing, of course I snaffled a couple and only yesterday repurposed a top plate from one, they were used for recording tensile tester readings amongst other things.
I worked with a plotter which used this for paper automatically fed from a roll.
Problem was, sometimes the voltage collapsed with an audible “tick” (probably a spark discharge somewhere in the works) and the paper bent away from the bed. The next large pen movement then destroyed the drawing it has spent half an hour more to create.
Good times!
I wonder if NASA has ever considered using electrostatic plates for sample collection in space. I’m imagining a probe passing through a comet tail once or twice with a folding array of these with an adhesive layer on top to bind the particles to the surface once the power is turned off. Maybe its not a great way to do it, but i’m thinking of the fact that it actively pulls things to it may allow it to collect more material than just hoping something passively hits a collector.
Or maybe on a (mars) rover to collect samples without having to outright scoop it up. May even be a good way to remove the already analyzed particles from an instrument as well.
Fly paper might be more weight saving.
Where would they find flys in space?
alien killer flies?
EEVdave recently did a teardown of a modern electrostatic whiteboard that some company sent to him for free. https://www.youtube.com/watch?v=MsNbK7kCcKA
“It seems that soldermask is not a reliable insulator at such high voltages.”
The sides of the traces are usually not coated very consistently. I don’t think UL allows soldermask to be considered an insulating barrier for the purpose of complying with minimum creepage spacings for that reason.
I did something similar to this a few years ago while researching surfaces to use on a 3D printer bed. I took the easy way out- just aluminum foil tape laid in tracks on one side of a thin piece of polycarbonate. I used a $3 DC-HVDC converter from ebay to step 12V up to about 6 kV. It worked well for holding paper on the side opposite the metal tape. Obviously it can easily be scaled to any size – just use a bigger sheet of plastic and more foil tape.
If you use white plastic, you can write on the surface with dry-erase markers and stick paper notes to the board, too.
Thanks for this, it was the first application I thought of since people work so hard to get a surface that FTM materials will stick to. The advantage being presumably that with power removed the “print” can be removed more easily
I use a plate like that, with HV, as dust collector. Since there is more (fine) dust in the air since i do not use a CRT monitor in my workingplace anymore.
In my mind, this gets filed away right next to the electropermanent magnet, as a weird way to stick things to things.
I’d love to see a teardown and review of the NicoDrone EPM, by the way. :)
These could be useful as dust traps too, for areas or equipment that are sensitive to dust such as anything with optics.
How dangerous is this? If the insulation fails and you touch the plate, will you be killed directly or just receive a harmless shock like from static electricity?
Some guy will try it, and either report back to us or not.
Oh, I got already shocked, it is harmless. There is a resistor in series, so you can’t really get hurt serious, but it hurts much much more then just a electrostatic shock.
Tried with ~15 kV and two strips of aluminum tape the other day. Got no noticeable attraction, but I’m not using interlocking fingers, either. That’ll be my next attempt.
The “main” recipe broken down, is: more voltage = more adhesion, smaller electrode-gap = more adhesion, finer electrode mash = more adhesion and being closer to the object = more adhesion.