from the not-the-pen-to-hand-your-kids dept.
Conductive inks made from silver nanoparticles have been available for some time; recently, a group at Georgia Tech demonstrated a way to use them in inkjet printers to create custom circuits. But they are quite pricey, and I'm not keen on the idea of pumping metal through my printer. In contrast, this new ink can be used in an ordinary roller-ball pen to draw circuit traces, and the recipe for making the ink is amazingly straightforward: Mix 75.5 parts gallium with 24.5 parts indium in a beaker of deionized water, heat to 50 °C, stir, and voilá: an alloy that's liquid at room temperature, costs about US $1 per milliliter, and is two orders of magnitude more conductive than the nanoparticle inks; its resistivity is just 17 times that of copper. This I had to try.
I phoned the senior author on the paper, professor Jing Liu of the Technical Institute of Physics and Chemistry at the Chinese Academy of Science, in Beijing, to check that this was really something I could do at home. Use 99.9 percent pure gallium and indium, he advised; I bought the metals from GalliumSource.com for about $130. The pen cartridge needs to be completely clean before filling, and the liquid alloy must be free of any solid bits that might clog the tip. Most important, write on plastic transparencies. The surface tension of the ink is so high that it beads up on paper.
Is this a good candidate to use at a school maker space to teach circuits, ie. by writing them on paper?
(Score: 4, Touché) by FatPhil on Tuesday September 29 2015, @01:02PM
What was the problem with breadboards? Most components with legs have legs stiff enough that you can bend them and hand-wire-wrap (and even get fancy with solder if you think you want it permanent) onto one of the legs when the 1.5D geometry of breadboards gets too restrictive. The crossovers in my hand-made speakers have got caps and things which are just floating in mid-air, soldered to other things that are sticking up proud from the board. When the boards are restrictive - ignore them!
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
(Score: 3, Insightful) by VLM on Tuesday September 29 2015, @01:28PM
What was the problem with breadboards?
There's a fixation in the field with 3-d printing things and then using conductive ink to make circuits. Because PCBs work well but they're NIH. So the java programmers teaching themselves to solder (aka "makers") have to do it another way because NIH. Can't do what ham radio operators have been doing for half a century because NIH.
Given that you basically have a solder that never solidifies, I'd be very nervous about migration into component packages.
As far as practicality, aluminum plus gallium is entertaining and is a perennial hollywood security theater terrorist plot. If you buy a kilo of the stuff expect to get put on a list somewhere, however impractical it is as a real weapon. So I would be careful not to use or store this alloy anywhere near aluminum.
On the topic of aluminum, indium is the "magic component" of at least some aluminum solders. Yes you can solder aluminum, you just can't use tin/lead alloy, you need an indium alloy solder (a couple of inferior alternative solder alloys exist)
(Score: 3, Interesting) by jcross on Tuesday September 29 2015, @03:03PM
I'm not saying this particular ink is necessarily any better, but I did some soldering as a kid and wound up with some painful burns, cold-soldered joints that never worked right, and burnt components. It's not the kind of thing that schoolkids can just pick up and run with without some dedicated practice. Wire wrap is cool, but does require a bit of fine motor skill to make sure everything is in the right place. Being able to draw circuits starts to sound closer to playing, which IMO is a good way for kids to start out engaging with tech.
(Score: 0) by Anonymous Coward on Tuesday September 29 2015, @03:47PM
but does require a bit of fine motor skill to make sure everything is in the right place
Surgery also requires fine motor skills. If you don't have them then do something else with your time.
Its like someone wants people to do things they really shouldn't be doing. If they want to do something, let them. If they don't want to, don't make them.
(Score: 3, Interesting) by VLM on Tuesday September 29 2015, @04:37PM
AC is overly harsh, but there is a stereotype in ham radio that at least 99% of the population doesn't have the slightest problem assembling PL-259 connectors, powerpole connectors, or doing surface mount work, aside from the usual unavoidable comedy (forget to put the shell on the PL-259 before soldering it on, put the powerpole connector together backwards, etc) but the 1% that has trouble makes sure Everyone hears about it. Its an electronics meme to go around saying nobody can do XYZ even though almost everyone does XYZ just fine. Also anecdotally there must be 1000 alternative procedures to assemble PL-259 connectors, at least one of them will probably work if the official way fails. The analogy with general circuit fooling around is breadboards are the standard but there are hundreds of alternatives. Spring clips, those lego like things, just twisting wires together, alligator clips all over the table... and apparently this inky thing. I went to a makerfair kinda recently and saw conductive clay too as an alternative.
One interesting problem some electronic/ham people have is being so cheap they make their own antenna wire by grabbing both sides of a copper penny and pulling really hard. In the real world using new clean parts and quality gear things are extremely easy, but there's plenty of people out there trying to re-use old PL-259s that have sat out in the rain for 25 years to get a nice green patina of corrosion and they get desoldered off the water soaked coaxial cable using a propane torch which sets the internal insulator on fire and then "surprisingly" trying to reuse both the corroded cable, rusty connector, and a 5 watt $6 radio shack soldering iron with a rusty tip is somewhat frustrating, and the point of this is soldering is REALLY easy, so if in one individual situation isn't, the problem is likely the gear or the parts, not the operator.
Another final comment is patience, I'm sure my first 100 solder joints were somewhat inferior to my 10000th which wasn't as good as my 100Kth connection.
Something I just thought of is things get interesting when you probe circuits... stick a voltmeter here or break the circuit and put a current meter there, or more advanced you have scopes and counters and all manner of things, and the instrument probe tips are all going to get coated in liquid indium/gallium, which sounds messy.
(Score: 3, Interesting) by jcross on Tuesday September 29 2015, @09:20PM
My real point here, to continue with your ham radio example, is that 99% of the general population doesn't care to assemble even one PL-259 connector, or at least doesn't care enough to jump the basic hurdles required to do it. If your aim is to get a kid interested in electronics, presenting them with a soldering iron and some components makes it likely they will just give up in frustration, especially without an adult who can give them lots of one-on-one help and encouragement. My dad told me stories about a friend of his growing up who built his own ham set, and I always thought that was really cool, but you need a lot of motivation to do that; the end result needs to be really worth it. Back in the day, talking to someone on another continent for free must have been a big draw, whereas nowadays that's quite easy. If you need to learn to solder just to get to the end result of having some blinkenlights... well, most kids are likely to give up before they get there.
Luckily, as another poster mentioned, we have proto boards, which are easy, effective, and safe. The only "problem" I see with them is that it takes some thinking to match the jumble of wires up with the schematic, whereas a circuit drawn on paper should match up pretty directly, just like copying a picture. Not that it's really a problem to make kids reason a bit.
(Score: 3, Interesting) by VLM on Tuesday September 29 2015, @09:44PM
Course there are no shortage of truly entry level prototyping instructions that do in fact provide pix of wiring on a breadboard... I just randomly clicked around on the adafruit site for awhile and found:
https://www.jeremymorgan.com/tutorials/raspberry-pi/how-to-weather-station-raspberry-pi/ [jeremymorgan.com]
As per the pix, put the red wire in that exact breadboard hole, etc.
There is one huge problem with drawing ckts is that I've been doing this forever yet my diagrams, at least first draft, inevitably contain little ohm shaped "jump" symbols to jump one wire over another. Plenty of cool circuits that can only be built in 3-d with wires that cross over each other and not in 2-d due to seemingly random assignment of pins on some integrated circuit. There's a classic mental puzzler along the lines of build me an XOR gate without any wires crossing over (aka 2-d diagram) and its trickier than you'd think, its awful looking and takes like 20 NAND gates so its dumb, but it can be done.
(Score: 2) by jcross on Wednesday September 30 2015, @12:52AM
Yeah I'd imagine in a drawn circuit you'd need to do the jumps with stickers or something like that.
(Score: 3, Touché) by Freeman on Tuesday September 29 2015, @05:34PM
Why would you want to take away the learning aspect of burns?
Joshua 1:9 "Be strong and of a good courage; be not afraid, neither be thou dismayed: for the Lord thy God is with thee"
(Score: 2) by jcross on Tuesday September 29 2015, @08:45PM
Oh I'm not saying I would change how I learned to solder, just that schools are unlikely to let kids mess around with soldering irons. Even if we did have an education system that valued the school of hard knocks, one student burning a neighboring one (accidentally or on purpose) is a whole other kind of learning experience that a teacher might not want their class getting into. Suffice it to say we're not going to see soldering in elementary schools any time soon.
(Score: 0) by Anonymous Coward on Thursday October 01 2015, @02:35AM
I self-taught myself to solder by putting together my Heathkit alarm clock. Nothing like a project to motivate one to learn.
(Score: 0) by Anonymous Coward on Tuesday September 29 2015, @08:11PM
But that's the whole point of breadboards--no soldering. You put your ICs in the middle, push your resistors or whatever other analog components you need into other spots, and then connect everything by pushing the ends of wires (jumpers) into holes. Of course this is only useful for prototyping, or learning, but is a million times more practical than liquids.
(Score: 0) by Anonymous Coward on Tuesday September 29 2015, @08:14PM
There are few things more likely to get a pitchfork and torches crowd going than poisoning children.
(Score: 0) by Anonymous Coward on Thursday October 01 2015, @02:39AM
And when you go to pry up that 555 chip with your fingers, you know, that one chip that feels like it is glued down on the board, then when it finally pops up, it doesn't come up straight so it flips over between your fingers and you find that it is now firmly embedded in the tip of your thumb.
(Score: 2) by darkfeline on Tuesday September 29 2015, @10:11PM
This would be easier for quickly testing designs than a breadboard. I've worked a fair bit with breadboards making a computer for a college course, and I can say that I would much rather work with the pen in the article than a breadboard plugging/pulling chips and wires if I just wanted to try out something.
Join the SDF Public Access UNIX System today!
(Score: 0) by Anonymous Coward on Tuesday September 29 2015, @11:00PM
The 1st time one path has to cross another path, you're right back to wires.
Dead-bug construction|Manhattan-style construction[1] [k8iqy.com] would take less time that just preparing the (spotlessly-clean) pen the liquid metal method requires.
[1] For the truly frugal|geographically-isolated, using silicone glue (or no glue at all) on your isolation cutouts [wordpress.com] makes your copper-clad FR4 potentially infinitely reusable.
-- gewg_
(Score: 2) by c0lo on Tuesday September 29 2015, @01:42PM
Cheap diy conductive ink - add enough graphite powder in acrylic paint/ink.
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 2) by MrGuy on Tuesday September 29 2015, @05:27PM
Inks are liquids that dry to produce a solid permanent deposition of a solid.
what we have here simply is a liquid. yes, you can deploy it with a pen, but it never "dries". Which means it's never permanent. It can always be wiped/smeared away. It will always run if not placed on a completely flat surface. You can never "print" something with it that you expect to stay how you printed it.
Don't get me wrong. Gallium' wicked cool. And using it to create circuit paths is a cool idea. But calling it metallic ink is disingenuous.
(Score: 1, Interesting) by Anonymous Coward on Tuesday September 29 2015, @09:59PM
it never "dries"
...and it's on a flimsy substrate.
...and it cost him $130 to get started.
It can always be wiped/smeared away
Yup. If you repeatedly need a tiny (single-layer) something to do a task for a few hours, yeah, this could be useful.
If you need to move your gizmo to a new location, the luster of this notion quickly fades with the 1st guy who is the slightest bit fumble-fingered.
The prevalence of physical prototypes of electronic subassemblies among professionals has been asymptotically zero for a decade.
Pros skip that and go right to a First Article.
Circuit simulation software (SPICE) is the way most folks try out their ideas these days.
(If your potential vendor does not supply useful models for his stuff, you need a vendor that doesn't suck.)
Add to that that the most popular SPICE is the most popular one because it is freeware and its developer/maintainer has made very sure that it can always run on multiple platforms (via WINE) and has done that for over a decade. [google.com]
There are also several instances of SPICE that are gratis and libre.
The extremely low cost and fast turnaround of printed circuit houses in e.g. China and Bulgaria makes DIY anything PWB-related a poor use of a pro's time.
...and, as mentioned in a previous related thread, [soylentnews.org] as soon as you need to draw any significant current, the resistivity of this whiz-bang printed stuff makes it impractical.
-- gewg_
(Score: 0) by Anonymous Coward on Tuesday September 29 2015, @08:36PM
No, I don't work for the company nor sell nor make $ on this, but I bought some recently and it's the bomb: http://www.mgchemicals.com/products/prototyping-and-circuit-repair/circuit-repair/nickel-print-840/ [mgchemicals.com] I got it for $12.
(Score: 2) by seeprime on Tuesday September 29 2015, @09:15PM
I've formulated silver, and other, conductive coatings. The pigments they used in this ink have a much higher resistance than any properly designed silver coating does. Silver is simply more conductive and works better. The pigment volume concentration can be changed to allow different levels of conductivity in any conductive coating. The problem with a silver ink or coating is that the silver will eventually tarnish, and lose some conductivity, if not clear coated upon completion of the task.
(Score: 2) by Gravis on Tuesday September 29 2015, @10:43PM
Not as conductive as silver
duh! silver is the most conductive element!