Resistance, Capacitance, Inductance, and now MEMRISTANCE

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al hildenbrand

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memristor01.jpg


I heard a short report on National Public Radio's Science Friday about a working prototype device that is a new fundemantal circuit element.

Enter the "memresistor" or memristor.

Resistance, capacitance and inductance are the three fundemental circuit elements prior to this development.

A memristor, when voltage is removed from a circuit, remembers the voltage, and the duration of the voltage. The "memory" does not degrade with time. . .seconds, days, weeks, no matter.

The prototype is made from titanium dioxide + dopants and is made at integrated circuit chip nanometer dimensions.

Read more at this IEEE Spectrum article.
 

72.5kv

Senior Member
very interesting article. From the information in the article memristance can may lead to even faster processors. maybe tera byte processors
 

crossman

Senior Member
Location
Southeast Texas
After a superficial read of the material, I don't see that this qualifies as a fourth type of fundamental circuit element. So it is a variable resistor that changes with voltage and remains with the value of resistance when it was last turned off? Still sounds like resistance to me. We have all sorts of devices whose resistance depends on voltage, time, the twisting of a handle, amount of light, etc.

Seems we could build a memristor with a variable resistor and some kind of a voltage-sensitive positioning servo.

And as for rebooting computers, when I want to reboot, I want the #%*$# to reboot, not come back to the state it was in when I shut it off!

Edit: Of course, these guys are way smarter than me, so maybe there is more to it than what the article contains.
 

crossman

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It may well be a fantastic new discovery which leads to all kinds of advances. But to call it a newly discovered circuit element on the fundamental level of R, XL and XC may be stretching it.

I would like to know more, suppose it is time for research unless any Forum brainiacs can 'splain it to me.
 

al hildenbrand

Senior Member
Location
Minnesota
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Electrical Contractor, Electrical Consultant, Electrical Engineer
crossman said:
Seems we could build a memristor with a variable resistor and some kind of a voltage-sensitive positioning servo.
LOL :smile: That's very steam punk.

Now, make it small. . .say 90 nanometers across, and instead of a couple machines kludged together, do it as a single solid state circuit element.
crossman said:
And as for rebooting computers, when I want to reboot, I want the #%*$# to reboot, not come back to the state it was in when I shut it off!
Think of the reboot this way - fold up the laptop to travel, and when the screen latches to the keyboard, the battery disconnects. Hours or days later, you open the laptop to the same computational state you left it with no drain on the battery having occured.
 

steve66

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Location
Illinois
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Engineer
Since an inductor and capacitor can produce resonance, I wonder what we can get with a resistor and a memoristor. Memorance?

Steve
 

crossman

Senior Member
Location
Southeast Texas
al hildenbrand said:
LOL :smile: That's very steam punk.

Now, make it small. . .say 90 nanometers across, and instead of a couple machines kludged together, do it as a single solid state circuit element.

So you are viewing this as a newly discovered fundamental element of electrical science along the lines of R, XL, and XC? So, to be completely correct, the impedance formula needs to be reworked to include this fourth element?
 

al hildenbrand

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Location
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Electrical Contractor, Electrical Consultant, Electrical Engineer
crossman said:
So you are viewing this as a newly discovered fundamental element of electrical science along the lines of R, XL, and XC? So, to be completely correct, the impedance formula needs to be reworked to include this fourth element?
Here, read this. It's from the article from the IEEE Spectrum article I link to in my opening post.
The memristor's story starts nearly four decades ago with a flash of insight by IEEE Fellow and nonlinear-circuit-theory pioneer Leon Chua. Examining the relationships between charge and flux in resistors, capacitors, and inductors in a 1971 paper, Chua postulated the existence of a fourth element called the memory resistor. Such a device, he figured, would provide a similar relationship between magnetic flux and charge that a resistor gives between voltage and current. In practice, that would mean it acted like a resistor whose value could vary according to the current passing through it and which would remember that value even after the current disappeared.
Then consider the diagram in the article, that is, the second image.
 

ELA

Senior Member
Occupation
Electrical Test Engineer
I can't wait for the 5th Element!

Oops ... saw that already...
 

mivey

Senior Member
ELA said:
I can't wait for the 5th Element!

Oops ... saw that already...
Shucks. Why didn't I think of that one? The best come-backs always seem to dawn on me after I'm already on my way home.:smile:
 

al hildenbrand

Senior Member
Location
Minnesota
Occupation
Electrical Contractor, Electrical Consultant, Electrical Engineer
crossman said:
anything that can be described as a variable resistance is a variable resistance.
Your model of a voltage sensing servo motor twisting the armature of a potentiometer, while producing the same circuit effects, relies on:
  1. large construction (fractions of inches or larger - macro scale),
  2. conversion of electromagnetic energy to mechanical motion and then mechanical motion back to electromagnetic energy,
  3. high power consumption to vary the resistor.
As the Spectrum article states, that solution to the theoretical concept was dismissed as a dalliance, that is, as possible, but of limited practical value. The article also implies there were other solutions to the principle of memristance than em - mech - em which were also dismissed.

The new breakthrough from Hewlett Packard's Stanley Williams, et. al., is that at micro levels small enough that quantum physics plays an important role, a single solid state construction of titanium dioxide + dopants exhibits the memristance properties predicted almost forty years ago by Leon Chua. This is exciting because it apparently fits very well into the world of integrated circuits, which a servo - pot would not.

What holds my attention is the symmetry of the relationships of charge, current, voltage and flux that occurs when the principle of memristance is included in the diagram in the Spectrum article (the second image).

The rules of resistance, inductance and capacitance are not to be re-written, only added to, and the addition is memristance.
 

crossman

Senior Member
Location
Southeast Texas
al hildenbrand said:
Your model of a voltage sensing servo motor twisting the armature of a potentiometer, while producing the same circuit effects, relies on:
  1. large construction (fractions of inches or larger - macro scale),
  2. conversion of electromagnetic energy to mechanical motion and then mechanical motion back to electromagnetic energy,
  3. high power consumption to vary the resistor.
From a theoretical viewpoint, I don't see that these 3 points have anything to do with it. What does size matter? If I can take the three original fundamental electrical elements R, XL, and XC and build a "new" component, then that "new" component is certainly not a "fundamental element" of electricity.

What holds my attention is the symmetry of the relationships of charge, current, voltage and flux that occurs when the principle of memristance is included in the diagram in the Spectrum article (the second image).

I understand, but is there anything that says the relationship must exist? And for me, I would certainly expect the new element to exhibit "peculiar" characteristics beyond that of a varying resistance.

The rules of resistance, inductance and capacitance are not to be re-written, only added to, and the addition is memristance.

Understood. Maybe Z = sqrt(R^2 + (XL^2 - XC^2) + M^2) ? I wonder what the formula for M would be.

Now, the peculiar and interesting thing to me is that none of the engineers and theoretical members are even acknowledging this thread. Maybe they are off doing research before spouting off with no prior knowledge like I have done so far?
 

mivey

Senior Member
crossman said:
From a theoretical viewpoint, I don't see that these 3 points have anything to do with it.
I don't either.
crossman said:
I understand, but is there anything that says the relationship must exist?
I'm not sure
crossman said:
And for me, I would certainly expect the new element to exhibit "peculiar" characteristics beyond that of a varying resistance.
It does. It has memory
crossman said:
Maybe Z = sqrt(R^2 + (XL^2 - XC^2) + M^2) ? I wonder what the formula for M would be.
Don't know yet.

Well, I guess we have some reading to do as it appears to be more than a variable resistor and is certainly not the digital pot linked in post #4 as that is not the kind of memory I think they are talking about.
 

ELA

Senior Member
Occupation
Electrical Test Engineer
By nature I am resisting the idea that this should be considered a 4th passive element of electrical devices.

From what I have read about the definition of passive vs active devices I can see why some are calling it that.

I could use further convincing though myself. I sure don't like the idea of re-learning a bunch of electrical equations.
 
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