This is an instructable on the best conductive glue I have been able to make that uses easy to obtain materials, glues well to most materials, is quite flexible and has a low resistance. Unfortunately for me, it uses a rubber or plastic mixture that I do not know the chemical composition of, so I cannot patent it.
There are many kinds of conductive epoxies, glues, and rubbers available. Unfortunately, they are for the most part quite expensive.
So, for more than four years, I have been trying every possible combination of likely elements, compounds, and solvents that I could get my hands on, in order to make my own truly affordable conductive glue. While I have found several that have excellent low conductivity, they tend to be quite brittle and have a tendency to crack. The conductive glue presented here does not have these problems.
Because this glue is quite flexible and you can vary its resistance, it has potential for different kinds of paint on sensors for robots or other devices. It should be possible to paint on strain gauges on the outside of a regular glove and use it for virtual reality or other control possibilities. Touch sensors and membrane switches can be painted on various flexible or rigid surfaces.
It can be used to paint on wires and resistors and as a glued solder joint. It can also be used to paint on strain gauges, temperature sensors, electromagnetic shielding, antennas, and push-button switches. I suspect, that with more experimentation, it may be possible to use it to create capacitors, diodes and transistors.
There are many kinds of conductive epoxies, glues, and rubbers available. Unfortunately, they are for the most part quite expensive.
So, for more than four years, I have been trying every possible combination of likely elements, compounds, and solvents that I could get my hands on, in order to make my own truly affordable conductive glue. While I have found several that have excellent low conductivity, they tend to be quite brittle and have a tendency to crack. The conductive glue presented here does not have these problems.
Because this glue is quite flexible and you can vary its resistance, it has potential for different kinds of paint on sensors for robots or other devices. It should be possible to paint on strain gauges on the outside of a regular glove and use it for virtual reality or other control possibilities. Touch sensors and membrane switches can be painted on various flexible or rigid surfaces.
It can be used to paint on wires and resistors and as a glued solder joint. It can also be used to paint on strain gauges, temperature sensors, electromagnetic shielding, antennas, and push-button switches. I suspect, that with more experimentation, it may be possible to use it to create capacitors, diodes and transistors.
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Signing UpStep 1: Materials for the Conductive Glue and Circuit
Carbon Graphite, fine powder-Available in larger quantities at http://www.elementalscientific.net/
Available in smaller quantities at your local hardware store. It's called lubricating graphite and comes in small tubes or bottles. The brand I used successfully is called AGS Extra Fine Graphite, but no doubt there are other brands that will also work.
Performix(tm) liquid tape, black-Available at Wal-Mart or http://www.buytape.com
Mixing cups or glass container
1/4 and 1/2 teaspoon measuring spoons
Glass or plastic mixing rod
Cardboard for stencil
Toluol paint thinner (optional)-Available at most hardware stores.
Conductive thread (optional)-Available in larger spools at http://members.shaw.ca/ubik/thread/order.html It is available in smaller spools at
http://www.Inklesspress.com/electronic_parts_2.htm
Circuit materials of your choice
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Being cheap, I first tried a variation of the conductive glue idea using filed aluminum from a soda can aand clear paper glue, but it yielded 0 conductivity. I was forced to spend $2 on the lubricating graphite and try again, still with the Pentel brush glue as the base. It worked, but very weakly. The resistance was so high 2 AA batteries could barely make it through to light up an LED. I then tried wood glue as the base but came up with 0 conductivity.
Sadly, my attempts at being MacGuyver all came up very short. I went out spent $8 bought some black liquid elec tape (Blue Magic brand) and tried again. YET AGAIN the conductivity was very poor, although slightly better than with the clear paper glue. But it was still too weak for a the chip in the keyboard to detect the signal. Unless I'm doing something terribly wrong, the graphite just doesn't seem conductive enough for almost any purpose to me.
My last attempt involved gluing a staple to the keyboard membrane over the bad trace which looks like it is allowing slightly more current through. I have to wait for it to dry and see...
Any of you thinking you can use this in place of solder, think twice.
I would really appreciate, if you could help. Though knowing instructables, i came here via your website and i'd say that the pict of your trials with different materials are proof enough of your competence, so maybe could you even give a comment about the benefit of the alien howto?
Greetz,
Luke
Could i use the conductive glue you have explored to connect a copper tab to a battery post?
The glue needs some strength and low resistance and carry some amps of current.
Thanks, olrob
This glue has too much resistance to carry large amounts of current.
With amps it will start to smoke.
A 14.4 V Craftsman NICD battery pack delivers from 1.2 to 2.2 amps (quality & price). It contains 12 1.2 V cells in series. NiMH cells can produce 3.2 to 4.5 amps at 1.2 V. Li-Ion cells are rated at 3.6 V and 2.6 amps each.
One of my applications is a Skil Twist battery powered screwdriver. It uses 2 NICD cells in series for 2.4 V and 2 amps in an intermittent operation. I would guess that each screwing operation would have 30 seconds on and 30 second off.
My Craftsman 14.4 v power screwdriver would work about the same (2 amps for 30 seconds).
Would your lowest resistance mixtures still smoke with a 2 amp 30 second cycle?
Thanks again.
This instructable has tremendous value for low-current devices in creative uses. I've had great luck with Circuit Writer pens from Mouser and Radio Shack, but they're expensive ($20), have a small quantity, and dry out in about a year.
If you want to try your luck, consider adding surface-mount LED's, capacitors and resistors directly to the pins of a mini-DIP package. I once did this with a 556 timer, using bits of adhesive tape barriers to create power rails and conductive zones.
Thanks
Getting foil tape to make a good, strong connection to a flat surface is a challenge on its own... especially when higher currents are involved. One of the best ways to do this would be to use a small spring taped to the end of the battery, then slip the tape or wire under the spring to remain tightly fixed against it.
Nice I can use this. Thanks.
The link http://www.Inklesspress.com/electronic_parts_2.htm
for smaller spools conductive thread doesn't work.
buytape.com does though, and its run by the same people
btw, love this idea!!
I have made the correction.
And let us know if you discover anything interesting.
Very well done. I'm sure you've played down a little bit, the many hours you have invested in this (it must have been a huge job doing trial & error on all possible ingredients & various ratios). That alone, makes you a true "stand-up guy" for posting this as an "open source" formula. Also, I imagine those Liquid Tape guys would have some issues if you tried to patten a formula made of 50% of their product :-) I just wanted to add my thanks as this is something that many of us will use often.
Are you familiar with Sugru? Lots of info on this site. I wonder what you might be able to create by incorporating it into your graphite formula? Maybe a custom sized & shaped 3D switch, resistor, or volt reg / potentiometer disguised as some decorative part of a project? A more HD pressure sensor? I see a huge novelty market for fun car accessories such as the OEM-looking shift knob. You wire it so that it delivers a (safe but meaningful) "zzaaapp" every time your kid dives the family car like a race car? Electric side moulding for those inconsiderate people who lean against other people's cars as if they were beach chairs. Hmmm, I wonder if they'd even mix in a useful way. Hey great job and thanks for making it available to all.