what is a memristor and what are its uses

What is memristor

Memristor is a two-terminal device that can remember its history, and its resistance is depended upon the magnitude and polarity of the voltage applied to it and the length of the time that the voltage has been applied. So if the voltage is turned off the memristor can remember its most recent resistance until the next time when the voltage is turned on so if the voltage is turned on after several months it could remember the resistance during that period of months. Memristors can relate the charge moving through the circuit and the magnetic flux surrounded by that circuit. So the device resistance would vary according to the amount of charge that passed through it. A memristor can be said as a charge controlled when the relation between flux and charge is expressed as a function of electric charge and it is said to be flux controlled if the relation between the flux and charge is expressed as a function of the flux linkage.

What is a memristor used for and what is the specialty of a memristor

One of the important properties of a memristor is that it can save its electronic state even after the current is turned off, so because of this feature it can be used to replace today’s flash memory. It could remember a range of electrical states, and these characters cannot be replaced by any circuit combination of resistor, capacitor, and inductor. Memristor can be used to reduce the size of the supercomputers and it could also reduce the booting time of our PC. It can be used for the development of intelligent devices having memory, so it can be used to take artificial intelligence and robotics to the next level.

What is memristance

Memristance is the property of the memristor to retain its resistance level after the power had been shut down. Memristance of a memristor varies with the amount of charge that has passed through the memristor.

How does a memristor work

There are two layers of titanium dioxide film Tio2 and Tio2-x, the upper layer has a depletion of oxygen atoms and the vacancies of the oxygen are donors of electrons which makes the vacancies themselves positive charged. Tio2-x is a conductor and it has lower resistance, while the Tio2 is not a conductor.

If a voltage is applied to the electrode of the device then it will repel the oxygen vacancies in the Tio2 –x layer down into the pure Tio2 layer which converts the Tio2 into Tio2-x and makes it conductive and thus the device will turn on. The device will turn off if a negative voltage is applied. The oxygen vacancies in the Tio2-x manifest as bubbles of oxygen vacancies scattered throughout the upper layer and a positive voltage on the switch will repel the oxygen deficiencies in the metallic upper Tio2-x layer sends them into non conducting Tio2 layer and it will reduce the boundary between the two-layer and it will increase the conductivity of the Tio2-x and thus the entire switch conductivity increases. If the positive voltage is applied more then the cube conductivity increases. If a negative voltage is applied to the Tio2 it will pull out the positive oxygen bubbles which will increase the resistivity of the Tio2. So if we apply more negative voltage then the cube will become less conductive. So when the voltage is turned off the positive and negative oxygen bubbles do not migrate they will remain at their place and the boundary between the two titanium dioxide layers is frozen and that’s how the memristor will remember the last applied voltage.

What are the types of memristors

Spintronic memristor

In this type of memristor, the resistance is caused by the spin of electrons in one section of the device pointing in a different direction than those in another section, which will create a domain wall. The boundary between the two states, electrons which flows in the device has a certain spin, this will alter the magnetization state of the device. The change in magnetization will move the domain wall and changes the resistance.

Polymeric memristor

In this memristor, the dynamic doping of the polymer and inorganic materials is done to improve the switching characteristics and retention required to create the functioning non-volatile memory cells. Special passive layers are used between the active thin films and electrodes that will enhance the extraction of ions from the electrode

Three terminal memristor

Memristor is a two-terminal device, there was an implementation of three-terminal devices, which was developed by Bernard widrow. So in the three-terminal memristor, the conductance between the two of the terminals is controlled by the time integral of the current in the third. Reproducible elements have been made which are continuously variable and it vary in resistance from 100 to 1 ohms and cover this range in 10 seconds with several mille amperes of plating current. There is one disadvantage for widrow’s memristor that is they were made from an electroplating cell rather than a solid-state circuit element.

What are the advantages of a memristor

  • Memory devices which are built with memristors have a great data density
  • It combines the job of working memory and hard drives to one device
  • The information is not lost when the device is turned off
  • Quicker boot up is capable because there is no information lost when it is turned off
  • It provides greater reliability when power is interrupted in data centers
  • Memristors can handle more data

What are the applications of memristors

  • D-Ram in computers can be replaced because it lacks the ability to retain the information once they are turned off, but by using memristor this problem can be solved
  • It can be used for remote sensing applications
  • It can do complex mathematical calculations
  • The size of supercomputers can be reduced by using this and reduces the booting time of the PC.


post-graduate in Electronics & communication.

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