Memristor: New passive circuit element after R, L & C

We know three kinds of passive circuit elements quite well. The first and the foremost is resistor R, which gives a relationship between voltage and current (V = IR), then we are familiar with capacitor C, which is a charge storage element that tells us charge stored by capacitor is directly proportional to voltage applied (Q = CV) and third of course is an inductor L, which gives a relation between induced voltage in the inductor with rate of change of current (φ = LI, Where φ is a magnetic flux). In 1971, a researcher Leon Chua theorized the possibility of a passive component that gives a relationship between the charge and magnetic flux and it was named memristor M where (φ = MQ).

Relations of R, C, L and M with Voltage, Current, Charge and Flux.

As its name suggests, memristor "memorize" how much current has passed through it. In other words electrical resistance of memristor depends upon the history of current that has passed through it along with the direction of the current flow. When the power is turned off, memristor remembers its most recent resistance until power is turned back on, thus making a device non-volatile. This non-volatile property makes memristor a possible choice of making flash memories in future.

Symbol of memristor

Memristors will hypothetically be cheaper and far faster than flash memory of today, and would offer higher memory density. They could also replace RAM chips and make it non-volatile so after you turn off your computer it will remember exactly what it was doing when you turn it back on. Other than this non volatile memory applications there could be number of applications where memristor could be used in future like low power and remote sensing applications, as a replacement for transistors in integrated circuits design, analog computers, programmable logic, signal processing, neural networks etc

There are different types of memristors available depending upon the material of implementation like titanium dioxide memristor, polymeric memristor, layered memristor, ferroelectric memristor, carbon nanotube memristor etc. Currently there are many companies like IBM, HP, HRL, Samsung and many other research labs that are working on implementation of memristors using titanium dioxide.

By Neeraj Kumar - Assistant Professor, Chitkara University H.P.

Reference http://www.memristor.org