‘Memristor’ could one day mimic complex brain neurons

Computers that mimic the human brain in the way they process data have moved a step closer to reality thanks to new research from the US.

Researchers at Hewlett Packard (HP) and California University in Santa Barbara have used highly focused X-rays to, for the first time, map out the nanoscale properties of a newly understood circuit element called a memory resistor or ‘memristor’.

These have the ability to ‘remember’ how much electronic charge passes through them and one day may be able to act like synapses within electronic circuits, mimicking the complex network of neurons present in the brain.

HP, which first demonstrated memristors in 2006, believes the technology could lead to a wide range of novel applications, including semi-autonomous robots, if complex networks of neurons can be reproduced in an artificial system.

Computer scientists first need to understand the physical processes that occur within the memristors at a very small scale.

Memristors have a simple structure — often just a thin film made of titanium dioxide between two metal electrodes — and their electrical properties have been extensively studied.

The new research, published in the journal Nanotechnology, saw the first non-destructive study of memristors’ physical properties, giving a more detailed insight into their chemistry and the structural changes that occur when they are operating.

‘One of the biggest hurdles in using these devices is in understanding how they work: the microscopic picture for how they undergo such tremendous and reversible change in resistance,’ said John Paul Strachan of HP’s Nanoelectronics Research Group.

‘We now have a direct picture for the thermal profile that is highly localised around this channel during electrical operation and is likely to play a large role in accelerating the physics driving the memristive behaviour.’

The researchers were able to study the exact channel where the resistance switching of memristors occurs by using a combination of techniques.

They used highly focused X-rays to locate and image the approximately 100nm-wide channel where the switching of resistance takes place, which was then fed into a mathematical model of how the memristor heats up.