Fundamental electronics is being changed by the “memristor”, a device that basically acts like a variable resistor and is capable of remembering the state it was in. This is significant because a single memristor may be able to replace many transistors and capacitors, making possible much smaller electronic circuits, and because it seems that it would not need constant refreshing to maintain recorded information. First postulated in a research paper in 1971, the memristor was only a hypothetical device for thirty years until modern electronics began approaching the molecular scale.

Demystifying the memristor:
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By Jamie Beckett, April 2008

Researchers at HP Labs have solved a decades-old mystery by proving the existence of a fourth basic element in integrated circuits that could make it possible to develop computers that turn on and off like an electric light.

The memristor — short for memory resistor – could make it possible to develop far more energy-efficient computing systems with memories that retain information even after the power is off, so there’s no wait for the system to boot up after turning the computer on. It may even be possible to create systems with some of the pattern-matching abilities of the human brain.

A mathematical model and a physical example that prove the memristor’s existence appear in a paper published in the April 30 issue of the journal Nature.

The Mysterious Memristor – []

1 May 2008–Anyone familiar with electronics knows the trinity of fundamental components: the resistor, the capacitor, and the inductor. In 1971, a University of California, Berkeley, engineer predicted that there should be a fourth element: a memory resistor, or memristor. But no one knew how to build one. Now, 37 years later, electronics have finally gotten small enough to reveal the secrets of that fourth element. The memristor, Hewlett-Packard researchers revealed today in the journal Nature , had been hiding in plain sight all along–within the electrical characteristics of certain nanoscale devices. They think the new element could pave the way for applications both near- and far-term, from nonvolatile RAM to realistic neural networks.


By redesigning certain types of circuits to include memristors, Williams expects to obtain the same function with fewer components, making the circuit itself less expensive and significantly decreasing its power consumption. In fact, he hopes to combine memristors with traditional circuit-design elements to produce a device that does computation in a non-Boolean fashion. ”We won’t claim that we’re going to build a brain, but we want something that will compute like a brain,” Williams says. They think they can abstract ”the whole synapse idea” to do essentially analog computation in an efficient manner. ”Some things that would take a digital computer forever to do, an analog computer would just breeze through,” he says.

Synapse on a Chip – []

The memristor — the so-called “missing link of electronics” memory technology that can change its resistance in varying levels — has been around on paper for nearly 40 years. However it wasn’t until 2010 that a group at the University of Michigan led by Dr. Wei Lu demonstrated that it can be used to build brain-like computers in a paper just published in Nano Letters. New Scientist reports that “memristors can behave uncannily like the junctions between neurons in the brain.” Scientific American describes a US military-funded project that is trying to use the memristor “to make neural computing a reality.” DARPA’s Systems of Neuromorphic Adaptive Plastic Scalable Electronics Program (SyNAPSE) is funded to create “electronic neuromorphic machine technology that is scalable to biological levels.”


Just like a synapse, the memristor changes its resistance in varying levels. Dr. Lu found that memristors can simulate synapses because electrical synaptic connections between two neurons can seemingly strengthen or weaken depending on when the neurons fire. “The memristor mimics synaptic action,” Lu concludes. Dr. Nadine Gergel-Hackett at NIST acknowledges the Michigan team’s successful creation of a brain synapse analog. “This work is a large step towards the realization of biology-inspired computing,” she says.

6-Minute Memristor Guide – []

December 10, 2008 — R. Stanley Williams, whose team discovered the memristor (the fourth fundamental circuit element) gives us a quick whiteboard talk about how the device works.

Memory with a Twist: NIST Develops a Flexible Memristor – []

Electronic components that can flex without breaking are coveted by portable device manufacturers for many reasons—and not just because people have a tendency to drop their mp3 players. Small medical sensors that can be worn on the skin to monitor vital signs such as heart rate or blood sugar could benefit patients with conditions that require constant maintenance, for example. Though some flexible components exist, creating flexible memory has been a technical barrier, according to NIST researchers.

Hunting for a solution, the researchers took polymer sheets—the sort that transparencies for overhead projectors are made from—and experimented with depositing a thin film of titanium dioxide, an ingredient in sunscreen, on their surfaces. Instead of using expensive equipment to deposit the titanium dioxide as is traditionally done, the material was deposited by a sol gel process, which consists of spinning the material in liquid form and letting it set, like making gelatin. By adding electrical contacts, the team created a flexible memory switch that operates on less than 10 volts, maintains its memory when power is lost, and still functions after being flexed more than 4,000 times.

Flexible Chips Do the NIST Twist
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June 02, 2009 — Electronic memory chips may soon gain the ability to bend and twist as a result of work by engineers at the National Institute of Standards and Technology (NIST).

Printed Supercapacitor
Paper Batteries

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