Memristors -- Re-Write the EE Texts

Ah the wonders of wikipedia! While searching up data about cars (trying to convince my wife that I *really *can fit a C4 Corvette in the garage along with the motorcycles), I noticed the “news” link announcing the discovery of Memristors… the fourth fundamental electronic component (joining Capacitors, Inductors and Resistors).

Surely there is a Nobel prize in the offing for Leon Chua who predicted the memristor back in 1971, as well as the team at HP Labs who discovered a way to produce it and announced their discovery recently.

There are many articles on this topic, but the one I found best was here:

http://www.spectrum.ieee.org/may08/6207

It is discoveries like this that just floor me… apparently memristance had been observed for decades, but no one knew what they were looking at. It required nano-scale materials to make it so obvious that it couldn’t be ignored. Who knows how many other fundamental discoveries remain to be made and what practical applications they might have.

Jason

Wow, what a great article.

Thanks for pointing it out, Jason.

For us EE types, this is really new frontier stuff. Now to find real world applications for it :smiley:

No engineers were saying, “If we only had a memristor, we could do X,”

Now engineers will say:
“If only we had known about memristors earlier, we could have done X earlier.”

Logically, it seems like the dopant shifts themselves are volatile. How could one measure this resistance without changing its value?. Maybe they’ve reduced it down to a negligibility-based equation like the Fermi function? Or maybe their multimeters are just that good. Hmm.

Use an AC probe signal. The “dopant shift” thus averages out to zero.

No way this thread went without reply for 12 hours!

The classic analogy for a resistor is a pipe through which water (electricity) runs. The width of the pipe is analogous to the resistance of the flow of current—the narrower the pipe, the greater the resistance. Normal resistors have an unchanging pipe size. A memristor, on the other hand, changes with the amount of water that gets pushed through. If you push water through the pipe in one direction, the pipe gets larger (less resistive). If you push the water in the other direction, the pipe gets smaller (more resistive). And the memristor remembers. When the water flow is turned off, the pipe size does not change.

There has to be some student out there who will have some creative ideas of what to do with something like this.

Insta-on-off memory locations would mean longer battery life for … nearly everything these days, from phones to laptops to digital media. With memory that keeps its value after power loss, this would be possible. If it is truly as simple as the article makes it sounds, the whole power savings would be much more efficient since it’s faster than doing it with something like flash memory.

Eventually someone will apply the mathematical model to some obscure idea and BAM a brand new technology will be born. It’s like the guys in that article (and other articles found on this) have a small vision, but there are much broader implications for this. I wonder how HP will release/license this.

Great find dtengineering!

I’m trying to figure out how exactly you would go about using this for memory… the premise of this device is that it’s resistance changes as a charge flows through it, so I can understand how you could ‘store’ data in a memrister, but how do you retrieve it? You’d have to apply a voltage to the memrister to develop a voltage drop and discover how much resistance exists accross the memrister, but inhearantly wouldn’t that distort the value stored within the memrister?

Well, of course I’m thinking like you’re going to use these in an analog state (each memrister being able to store many values) but I suppose you could just run them in a maximum resistance/minimum resistance only type setup, in which case it’s much less likely reading the resistance would entirely destroy the value in the memrister, though as you read data out you would have to ‘restore’ the value after each read.

Maybe I’m missing something… gosh I wish I already had gone to college and had my EE degree. :o

As far as licensing/selling goes… you can bet it’ll be astronomically priced for the first few years. :ahh:

-q

p.s. Team numbers in everyday places: look when JesseK last edited. :smiley:

As Alan mentioned, if you read it with an AC current then you will have put a net zero current flow through it. (You slightly increase the resistance, then slightly decrease it, setting it back where it was.)

Also it is likely that the device may require significantly more current flow to set the value than it does to read the value.

I am sure, however, that the uses of this device will expand beyond merely memory in ways that we cannot, at present, imagine.

Jason

OK, so I am a curious geek. I had to know more, so I got the article: Nature 453, 80-83 (1 May 2008)

It is available online if you have a Nature subscription, or for a fee. If your school library has a subscription that may be your easiest route.

The gist is that for two-terminal circuit elements a non-linear relationship between electric charge and magnetic flux gives rise to a hysteretic relationship (read: memory) between current and voltage. The HP investigators who authored the Nature article cited above have realized an experimental memristive device using a thin film of titanium dioxide doped with oxygen-poor impurities; the missing oxygen acts as a mobile positive charge. The effect increases as the mobility of the dopant increases, and as the length of the film decreases – so nanoscale devices look the most promising for potential applications.

Alan’s comment re: ac probing is consistent with the examples given by the authors of the Nature article.

[edit]

HP filed two US Patent Applications in April 2006 and February 2007, which became public last month. They are US2008/0090337 and US2008/0079029, respectively. Both describe electrically actuated switches based on the concepts described in the Nature article.

I interpret these US Patent Applications as a sign that HP, a company well known for technology leadership, anticipates that commercially viable devices will be made using these ideas.[/edit]

Holy crud, Batman.

This is astounding. I agree with the article, in that in 25+ years of design, I never had a need for a memristor - then again, I didn’t know it was one of the choices.

Nice find, and wow, what a time to be alive, eh?

Now to the magnetic monopole…

Don

Chua’s original paper

I just found it and won’t have time to read it until late tonight, so have fun until then. There’s a “download” button at the top.