Re: [beam] Re: Memristor
- I looked online for more elements that have been successfully used in
memristor design, and noted that there is mention of Silver Chalcogens
(Chalcogens are the the chemical elements in group 16 of the periodic
table. This group is also known as the oxygen family. It consists of
the elements oxygen (O), sulfur (S) <--(DING, DING, DING! We have
definitely seen Sulfur in the memristor discussion), selenium (Se),
tellurium (Te), and the radioactive element polonium (Po) <--(WAT!!! I
never realized Polonium is in the oxygen family). The defining
characteristic appears to be that they are all 2 electrons short of a
full outer shell.
This has me now VERY interested in experimenting with silver circuit
pens, as a copper (Cu), Copper Sulfide (Cu.xS.y), Silver (Ag) junction
might have some merit... I wonder, would the silver get any Sulfur
atoms off the Copper Sulfide, or if the bond is strong enough that it
would not significantly change.
On thought is using a recent ball point based silver gel pen for this.
Apply a coat of varnish over half the pad that has been reacted to
sulfur, then draw the silver trace from second copper trace, over the
varnish, and end the trace just as it goes over the varnish and
contacts the Copper Sulfide layer. Then after it dries, varnish over
the entire pad, potentially protecting the drawn trace, the sulfide
layer, and the junction.
Another thought I had, was to use the pen on a sheet of teflon. Allow
it to cure, mechanically or thermally anneal it, then peel it off the
teflon and stick the end in sulfur. If aluminum ended up being
critical to the junction, then maybe the PC board can be masked,
leaving only exposed copper pads, and the traces leading to them
electrically energized, and plate aluminum onto the pads.
I can either purchase the silver pen, or make high purity copper
paint. The copper paint involves dissolving and then mixing together
Ascorbic Acid with Coper Sulfate (NOT Sulfide... This stuff is a blue
powder/crystal). That will strip the copper sulfate of the sulfur
atoms and let copper nano particles precipitate out and sediment at
the bottom. After pouring off the liquid, you mix a little gum arabic
as a binder, and you have copper paint... Though it must be
mechanically or thermally annealed or oxidization due to porosity will
destroy its conductivity.
Either way, while the second method is an extraordinarily greater
amount of work... if silver directly on the Copper Sulfide does not
create a viable junction, the latter might. It might be possible to
hold the sulfide reacted metal "piece" against the plated aluminum
with a small point (pin, pen, etc coated with a release agent) to
create a positive contact surface, then place a drop of varnish or
epoxy over the entire lot... Something that cures quickly, and is
preferably thick, so as to not readily wick. That, hopefully would
seal the entire structure, and bind the chalcogenic metal pad in place
against the plated aluminum, with maintained positive contact at the
point of the pressure point generated by the tool used to hold it in
place. Flatten the tail of the metal against the board, and paint it
to the next trace on the PC board to complete the circuit, and maybe
drop another dab of epoxy/varnish to protect the entire thing.
Or we get lucky and discover we can just paint the junction on the
existing Copper Sulfide pad with a silver circuit pen! (crosses
fingers REALLY hard)!
HA! I realize I am essentially talking to myself by email! It really
is too early for me! XD
I hope people are still interested in the concept of homemade
Begin forwarded message:
> From: Richard Piotter <richfiles1@...>
> Date: March 11, 2013 4:22:15 AM CDT
> To: firstname.lastname@example.org
> Subject: Re: [beam] Re: Memristor
> Reply-To: email@example.com
> I was looking into memristors again, today. I saw a silver based
> circuit pen and it led me back to these ideas. Has anyone determined
> if a metal like silver can function instead of aluminum for the
> purposes of the point contact end of a memristor, or any other
> materials. I learned how to precipitate copper nano particles out of
> copper sulfate using ascorbic acid. You can make it into a paint using
> a little gum arabic. Only issue, is we can already make the copper
> traces. Aluminum would instantly oxidize, and I'm not sure if oxidized
> aluminum nano particles will conduct well enough or not.
> I repeat my old theoretical process in the cheap pic above. Could a
> silver based circuit pen take the place of the aluminum for the
> contact. I think this idea could have potential... It's similar to how
> planar transistors completely replaced point contact germanium
> transistors, and ultimately led the way to integrated circuits. The
> scale is obviously bigger, but the idea is the same. I might have to
> just suck it up and buy a circuit pen or two, maybe different
> formulas. It'll have to wait though, as I think I need to pay rent on
> time first!
> Richard Piotter
> Begin forwarded message:
> > From: Richard Piotter <richfiles1@...>
> > Date: July 10, 2012 3:11:33 PM CDT
> > To: firstname.lastname@example.org
> > Subject: Re: [beam] Re: Memristor
> > Reply-To: email@example.com
> > Ever used press-n-peel rub on pcb dry transfer decals to create
> > circuit boards?
> > I've used these before and they can produce some great results.
> > I've been wondering. If one were to place a pad over the Copper/
> > Sulphur layer, I wonder if having that uniformly sized hole over it
> > would allow a more consistent surface area and more consistent
> > characteristics from one point to another. I know the dry transfer
> > decals are intended to be scrubbed away after the copper clad
> board is
> > etched, but if you use the circuit pen technique to paint the
> > center hole to an adjacent copper pad, and then drop a dab of epoxy
> > over the whole lot, it may protect the whole thing.
> > Here's my most recent concept:
> > http://richfiles.solarbotics.net/robots/Memristor_PCB.png
> > Since the dry transfer decal is exactly that, a dry transfer, I
> > it'd have any effect on the surface. As far as I know, the
> material is
> > an insulator, and I suppose one could even get away with stacking
> > on top of one another for added thickness.
> > The only concern is hole size. Most are made for through hole
> > components. Some pads in the kit may have very small holes meant to
> > start a drill bit, but I don't know how many of those are included
> > a typical kit. I don't know if Radio Shack still carries these,
> but I
> > think they can still be found online.
> > One could also consider toner based art, using a transfer sheet, of
> > course that means more work aligning it all.
> > Richard Piotter
> > Begin forwarded message:
> >> From: "Andrew Hill" <curly.drew@...>
> >> Date: July 10, 2012 1:40:13 PM CDT
> >> To: firstname.lastname@example.org
> >> Subject: [beam] Re: Memristor
> >> Reply-To: email@example.com
> >> I got mine on eBay - it's sold for a few purposes and in pretty
> >> any quantity.
> >> Your right - remember to put sulpher on copper until a reasonable
> >> amount of corrosion builds up (for me this took about a week) - you
> >> can wipe it off and if there isn't enough corrosion just add some
> >> more sulpher.
> >> My goal is to more to control the contact point (size, pressure,
> >> thickness, etc) a bit, so that we have a reasonable range of
> >> accuracy. Nontheless the way you describe should produce a
> >> functioning Memristor :)
> >> One thing is that you only need a tiny contact area ("sharp end
> of a
> >> pin" tiny) of aluminium.
> >> If you are still in full time education I suggest getting the
> >> science department involved - I'm sure that one or more staff would
> >> be very interested in helping you with this. Plus they will
> >> have the necessary supplies and test equipment to hand.
> >> Thanks,
> >> Drew
Well, fsck me sideways with a broom! All these years I've been hallucinating that "R" in memistor. You are, of course, right.
Still, it seems to me a 3-terminal device would be handier than a 2-terminal device because then one could use the "neurons that fire together wire together" algorithm to automatically adjust the resistances of memistor synaptic weights.
During normal operation the memister works like an ordinary resistor, but during the adaptation mode (between firings?) inactive-exicitory and inactive-inhibitory memistors are left alone, while each memistor element that was active-exicitory when the neuron fired gets a dose of plating current to decrease resistance, and active-inhibitory memisters get reverse plating current to increase resistance.
There is the added complication that the old memistors used AC current during normal resistance mode (presumably to prevent plating action), but with modern semiconductor circuits it might not be necessary since the plating control electrode could be shorted to one end of the resistance with a transistor switch. Just thinking out loud, here.