It's called a Memristor?

So how exactly does a Memristor work?

Well an analogy that't there for a Memristor is that of a pipe that carries water.

The water itself is analogous to electrical charge, the pressure at the input of the pipe is similar to voltage, and the rate of flow of the water through the pipe is like electrical current. 

Just as with an electrical resistor, the flow of water through the pipe is faster if the pipe is shorter and/or it has a larger diameter. An analogy for a memristor is an interesting kind of pipe that expands or shrinks when water flows through it.  

If water flows through the pipe in one direction, the diameter of the pipe increases, thus enabling the water to flow faster. If water flows through the pipe in the opposite direction, the diameter of the pipe decreases, thus slowing down the flow of water. 

If the water pressure is turned off, the pipe will retain it most recent diameter until the water is turned back on. Thus, the pipe does not store water like a bucket (or a capacitor) – it remembers how much water flowed through it.

Technically though how does it work?

A Memristor is composed of a thin (50 nm) titanium dioxide film between two 5 nm thick electrodes, one titanium, the other platinum. 

http://ej.iop.org/images/0031-9120/48/3/317/Full/ped453020f2_online.jpg

Initially, there are two layers to the titanium dioxide film, one of which has a slight depletion of oxygen atoms. 

     The oxygen vacancies act as charge carriers, meaning that the depleted layer has a much lower resistance than the non-depleted layer. When an electric field is applied, the oxygen vacancies drift towards the non-depleted layer, changing the boundary between the high-resistance and low-resistance layers. causing the low-resistance area to grow and high-resistance area to shrink, lowering the resistance of the device 

     Thus the resistance of the film as a whole is dependent on how much charge has been passed through it in a particular direction, which is reversible by changing the direction of current, when this happens the oxygen vacancies are pushed back up to the top electrode, meaning the boundary has been pushed up creating a greater area of high resistance. 

Shown Below is a sample video explaining the memristor.

By Padraigh Walsh