Tag Archives: R. Stanley Williams

Memristors have always been with us

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Sprightly, a word not often used in conjunction with technology of any kind,  is the best of way describing the approach that researchers Varun Aggarwal and Gaurav Gandhi, along with Dr. Leon Chua, have taken towards their discovery that memristors are all around us. ( For anyone not familiar with the concept, I suggest reading the Wikipedia essay on memristors as it includes information about the various critiques of the memristor definition, as well as, the definition.)

It was Dexter Johnson in his June 6, 2013 post on the IEEE (Institute of Electrical and Electronics Engineers) Nanoclast blog who alerted me to this latest memristor work (Note: Links have been removed),

Two researchers from mLabs in India, along with Prof. Leon Chua at the University of California Berkeley, who first postulated the memristor in a paper back in 1971, have discovered the simplest physical implementation for the memristor, which can be built by anyone and everyone.

In two separate papers, one published in arXiv (“Bipolar electrical switching in metal-metal contacts”) and the other in the IEEE’s own Circuits and Systems Magazine (“The First Radios Were Made Using Memristors!”), Chua and the researchers, Varun Aggarwal and Gaurav Gandhi, discovered that simple imperfect point contacts all around us act as memristors.

“Our arXiv paper talks about the coherer, which comprises an imperfect metal-metal contact in embodiments such as a point contact between two metallic balls, granular media or a metal-mercury interface,” Gandhi explained to me via e-email. “On the other hand, the CAS paper comprises an imperfect metal-semiconductor contact (Cat’s Whisker) which was also the first solid-state diode. Both the systems have as their signature an imperfect point contact between two conducting/partially-conducting elements. Both act like memristor.”

I’ll get to the articles in a minutes, first let’s look at the researchers’ website, Mlabs home page (splash page). BTW, I have a soft spot for websites that are easy to navigate and don’t irritate me with movement or pop-ups (thank you mLabs). I think this description of the researchers (Aggarwal and Gandhi) and how they came to develop mLabs (excerpted from the About us page) explains why I described their approach as sprightly,

As they say, anything can happen over a cup of coffee and this story is no different! Gaurav and Varun were friends for over a decade, and one fine day they were sitting at a coffee house discussing Gaurav’s trip to the Second Memristor and Memristive Symposium at Berkeley. Gaurav shared the exciting work around memristor that he witnessed at Berkeley. Varun, who has been an evangelist of Jagadish Chandra Bose’s work thought there was some correlation between the research work of Bose and memristor. He convinced Gaurav to look deeper into these aspects. Soon, a plan was put forth, they wore their engineering gloves and mLabs was born. Gaurav quit his job for full time involvement at mLabs, while Varun assisted and advised throughout.

Three years of curiosity, experimentation, discussions and support from various researchers and professors from different parts of the world, led us to where we are today.

We are also sincerely grateful to Prof. Leon Chua for his continuous support, mentorship and indispensable contribution to our work.

As Dexter notes, Aggarwal and Gandhi have written papers about two different ways to create memristors, the arXiv paper, Bipolar electrical switching in metal-metal contacts, describes how coherers* could be used to create simple memristors for research purposes. This paper also makes the argument that the memristor is a fundamental circuit (a claim which is a matter of considerable debate as the Wikipedia Memristor essay notes briefly),

Our new results show that bipolar switching can be observed in a large class of metals by a simple construction in form of a point-contact or granular media. It does not require complex construction, particular materials or small geometries. The signature of all our devices is an imperfect metal-metal contact and the physical mechanism for the observed behavior needs to be further studied. That the electrical behavior of these simple, naturally-occurring physical constructs can be modeled by a memristor, but not the other three passive elements, is an indication of its fundamental nature. By providing the canonic physical implementation for memristor, the present work not only lls an important gap in the study of switching devices, but also brings them into the realm of immediate practical use and implementation.

Due to the fact that the second article, the one in the IEEE published Circuits and Systems magazine, is behind a paywall, I can’t do much more than offer the title and the first paragraph,

The First Radios Were Made Using Memristors!

In 2008, Williams et al. reported the discovery of the fourth fundamental passive circuit element, memristor, which exhibits electrically controllable state-dependent resistance [1]. We show that one of the first wireless radio detector, called cat?s whisker, also the world?s first solid-state diode, had memristive properties. We have identified the state variable governing the resistance state of the device and can program it to switch between multiple stable resistance states. Our observations and results are valid for a larger class of devices called coherers, which include the cat?s whisker. These devices constitute the missing canonical physical implementations for a memristor (ref. Fig. 1).

It’s fascinating when you consider that up until now researching memristors meant having high tech equipment. I wonder how many backyard memristor labs are going to spring up?

On a somewhat related note, Dexter mentions that HP Labs ‘memristor’ products will be available in 2014. This latest date represents two postponements. Originally meant to be on the market in the summer of 2013, the new products were then supposed to brought to market in late 2013 as per my Feb. 7, 2013 posting; scroll down about 75% of the way).

*’corherers’ corrected to ‘coherers’ Oct. 16, 2015 1345 hours PST.

A step closer to artificial synapses courtesy of memristors

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Researchers from HRL Laboratories and the University of Michigan have built what they claim is a type of artificial synapse by using memristors. From the March 29, 2012 news item on Nanowerk,

In a step toward computers that mimic the parallel processing of complex biological brains, researchers from HRL Laboratories, LLC, and the University of Michigan have built a type of artificial synapse.

They have demonstrated the first functioning “memristor” array stacked on a conventional complementary metal-oxide semiconductor (CMOS) circuit. Memristors combine the functions of memory and logic like the synapses of biological brains.

…

The researchers developed a vertically integrated hybrid electronic circuit by combining the novel memristor developed at the University of Michigan with wafer scale heterogeneous process integration methodology and CMOS read/write circuitry developed at HRL. “This hybrid circuit is a critical advance in developing intelligent machines,” said HRL SyNAPSE program manager and principal investigator Narayan Srinivasa. “We have created a multi-bit fully addressable memory storage capability with a density of up to 30 Gbits/cm², which is unprecedented in microelectronics.”

Industry is seeking hybrid systems such as this one, the researchers say. Dubbed “R-RAM,” they could shatter the looming limits of Moore’s Law, which predicts a doubling of transistor density and therefore chip speed every two years.

“We’re reaching the fundamental limits of transistor scaling. This hybrid integration opens many opportunities for greater memory capacity and higher performance of conventional computers.  It has great potential in future non-volatile memory that would improve upon today’s Flash, as well as reconfigurable circuits,” said Wei Lu, an associate professor at the U-M Department of Electrical Engineering and Computer Science whose group developed the memristor array.

This work is being done as part of a DARPA (Defense Advanced Research Projects Agency) project titled, SyNAPSE, from the news item,

The work is part of the Defense Advanced Research Projects Agency’s (DARPA) SyNAPSE Program, or Systems of Neuromorphic Adaptive Plastic Scalable Electronics. Since 2008, the HRL-led SyNAPSE team has been developing a new paradigm for “neuromorphic computing” modeled after biology.

While I haven’t come across HRL Laboratories before, I have mentioned Dr. Wei Lu and his work with memristors in my April 15, 2010 posting. As for HRL Laboratories, they were founded in 1948 by Howard Hughes as the Hughes Research Laboratories (from the company’s History page),

HRL Laboratories continues the legacy of technology advances that began at Hughes Research Laboratories, established by Howard Hughes in 1948. HRL Laboratories, LLC, was organized as a limited liability company (LLC) on December 17, 1997 and received its first patent on September 12, 2000. With more than 750 patents to our name since then and counting, we’re proud of our talented group of researchers, who continue the long tradition of technical excellence in innovation.

First Laser
One of Hughes’ most notable achievements came in 1960 with the demonstration of the world’s first laser which used a synthetic ruby crystal. The ruby laser became the basis of a multibillion-dollar laser range finder business for Hughes. In 2010 during the 50th anniversary of the laser, HRL was designated a Physics Historic Site by the American Physical Society and was selected an IEEE Milestones location as the facility where the first working laser was demonstrated.

HRL has organized its researchers in a number of teams, the one of most interest in this context is the Center for Neural and Emergent Systems,

Part of HRL’s Information and Systems Sciences Laboratory, the Center for Neural and Emergent Systems (CNES) is dedicated to exploring and developing an innovative neural & emergent computing paradigm for creating intelligent, efficient machines that can interact with, react and adapt to, evolve, and learn from their environments.

CNES was founded on the principle that all intelligent systems are open thermodynamic systems capable of self-organization, whereby structural order emerges from disorder as a natural consequence of exchanging energy, matter or entropy with their environments.

These systems exist in a state far from equilibrium where the evolution of complex behaviors cannot be readily predicted from purely local interactions between the system’s parts. Rather, the emergent order and structure of the system arises from manifold interactions of its parts. These emergent systems contain amplifying-damping loops as a result of which very small perturbations can cause large effects or no effect at all. They become adaptive when the component relationships within the system become tuned for a particular set of tasks.

CNES promotes the idea that the neural system in the brain is an example of such a complex adaptive system. A key goal of CNES is to explain how computations in the brain can help explain the realization of complex behaviors such as perception, planning, decision making and navigation due to brain-body-environment interactions.

This has reminded me of HP Labs and their work with memristors (I have many postings, too many to list here) and understand that they will be rolling out ‘memristor-based’ products in 2013. From the  Oct. 8, 2011 article by Peter Clarke for EE Times,

The ‘memristor’ two-terminal non-volatile memory technology, in development at Hewlett Packard Co. since 2008, is on track to be in the market and taking share from flash memory within 18 months, according to Stan Williams, senior fellow at HP Labs.

“We have a lot of big plans for it and we’re working with Hynix Semiconductor to launch a replacement for flash in the summer of 2013 and also to address the solid-state drive market,” Williams told the audience of the International Electronics Forum, being held here [Seville, Spain].

ETA June 11, 2012: New artificial synapse development is mentioned in George Dvorsky’s June 11, 2012 posting (on the IO9.com website) about a nanoscale electrochemical switch developed by researchers in a Japan.

Memristor update

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HP Labs is making memristor news again. From a news item on physorg.ocm,

HP is partnering with Korean memory chip maker Hynix Semiconductor Inc. to make chips that contain memristors. Memristors are a newly discovered building block of electrical circuits.

HP built one in 2008 that confirmed what scientists had suspected for nearly 40 years but hadn’t been able to prove: that circuits have a weird, natural ability to remember things even when they’re turned off.

I don’t remember the story quite that way, i.e.,  “confirmed what scientists had suspected for nearly 40 years” as I recall the theory that R. Stanley William (the HP Labs team leader) cites  is from Dr. Leon Chua circa 1971 and was almost forgotten. (Unbeknownst to Dr. Chua, there was a previous theorist in the 1960s who posited a similar notion which he called a memistor. See Memistors, Memristors, and the Rise of Strong Artificial Intelligence, an article by Blaise Mouttet, for a more complete history. ETA: There’s additional material from Blaise at http://www.neurdon.com/)

There’s more about HP Labs and its new partner at BBC News in an article by Jason Palmer,

Electronics giant HP has joined the world’s second-largest memory chip maker Hynix to manufacture a novel member of the electronics family.

The deal will see “memristors” – first demonstrated by HP in 2006 [I believe it was 2008] – mass produced for the first time.

Memristors promise significantly greater memory storage requiring less energy and space, and may eventually also be employed in processors.

HP says the first memristors should be widely available in about three years.

If you follow the link to the story, there’s also a brief BBC video interview with Stanley Williams.

My first 2010 story on the memristor is here and later, there’s an interview I had with Forrest H Bennet III who argues that the memristor is not a fourth element (in addition to the capacitor, resistor, and inductor) but is in fact part of an infinite table of circuit elements.

ETA: I have some additional information from the news release on the HP Labs website,

HP today announced that it has entered into a joint development agreement with Hynix Semiconductor Inc., a world leader in the manufacture of computer memory, to bring memristor technology to market.

Memristors represent a fourth basic passive circuit element. They existed only in theory until 2006 – when researchers in HP Labs’ Information and Quantum Systems Laboratory (IQSL) first intentionally demonstrated their existence.

Memory chips created with memristor technology have the potential to run considerably faster and use much less energy than Flash memory technologies, says Dr. Stanley Williams, HP Senior Fellow and IQSL founding Director.

“We believe that the memristor is a universal memory that over time could replace Flash, DRAM, and even hard drives,” he says.

Uniting HP’s world-class research and IP with a first-rate memory manufacturer will allow high-quality, memristor-based memory to be developed quickly and on a mass scale, Williams adds.

Also, the video interview with Dr. Williams is on youtube and is not a BBC video as I believed. So here’s the interview,

The memristor rises; commercialization and academic research in the US; carbon nanotubes could be made safer than we thought

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In 2008, two memristor papers were published in Nature and Nature Nanotechnology, respectively. In the first (Nature, May 2008 [article still behind a paywall], a team at HP Labs claimed they had proved the existence of memristors (a fourth member of electrical engineering’s ‘Holy Trinity of the capacitor, resistor, and inductor’). In the second paper (Nature Nanotechnology, July 2008 [article still behind a paywall]) the team reported that they had achieved engineering control.

I mention this because (a) there’s some new excitement about memristors and (b) I love the story (you can read my summary of the 2008 story here on the Nanotech Mysteries wiki).

Unbeknownst to me in 2008, there was another team, located in Japan, whose work  on slime mould inspired research by a group at the University of California San Diego (UC San Diego)  which confirmed theorist Leon Chua’s (he first suggested memristors existed in 1971) intuition that biological organisms used memristive systems to learn. From an article (Synapse on a Chip) by Surf daddy Orca on the HPlus magazine site,

Experiments with slime molds in 2008 by Tetsu Saisuga at Hokkaido University in Sapporo sparked additional research at the University of California, San Diego by Max Di Ventra. Di Ventra was familiar with Chua’s work and built a memristive circuit that was able to learn and predict future signals. This ability turns out to be similar to the electrical activity involved in the ebb and flow of potassium and sodium ions across cellular membranes: synapses altering their response according to the frequency and strength of signals. New Scientist reports that Di Ventra’s work confirmed Chua’s suspicions that “synapses were memristors.” “The ion channel was the missing circuit element I was looking for,” says Chua, “and it already existed in nature.”

Fast forward to 2010 and a team at the University of Michigan led by Dr. Wei Lu showing how synapses behave like memristors (published in Nano Letters, DOI: 10.1021/nl904092h [article behind paywall]). (Fromthe  HPlus site article)

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.”

I’m not sure if the research in Michigan and elsewhere is being funded by DARPA (the US Dept. of Defense’s Defense Advanced Research Project Agency) although it seems likely.

In the short term, scientists talk about energy savings (no need to reboot your computer when you turn it back on). In the longer term, they talk about hardware being able to learn. (Thanks to the Foresight Institute for the latest update on the memristor story and the pointer to HPlus.) Do visit the HPlus site as there are some videos of scientists talking about memristors and additional information (there’s yet another team working on research that is tangentially related).

Commercializing academic research in US

Thanks to Dave Bruggeman at the Pasco Phronesis blog who’s posted some information about a White House Request for Information (RFI) on commercializing academic research. This is of particular interest not just because of the discussion about innovation in Canada but also because the US National Nanotechnology Initiative’s report to PCAST (President’s Council of Advisors on Science and Technology, my comments about the webcast of the proceedings here). From the Pasco Phronesis posting about the NNI report,

While the report notes that the U.S. continues to have a strong nanotechnology sector and corresponding support from the government. However, as with most other economic and research sectors, the rest of the world is catching up, or spending enough to try and catch up to the United States.

According to the report, more attention needs to be paid to commercialization efforts (a concern not unique to nanotechnology).

I don’t know how long the White House’s RFI has been under development but it was made public at the end of March 2010 just weeks after the latest series of reports to PCAST. As for the RFI itself, from the Pasco Phronesis posting about it,

The RFI questions are organized around two basic concerns:

  • Seeking ideas for supporting the commercialization and diffusion of university research. This would include best practices, useful models, metrics (with evidence of their success), and suggested changes in federal policy and/or research funding. In addition, the RFI is interested in how commercialization ecosystems can be developed where none exist.
  • Collecting data on private proof of concept centers (POCCs). These entities seek to help get research over the so-called “Valley of Death” between demonstrable research idea and final commercial product. The RFI is looking for similar kinds of information as for commercialization in general: best practices, metrics, underlying conditions that facilitate such centers.

I find the news of this RFI a little surprising since I had the impression that commercialization of academic research in the US is far more advanced than it is here in Canada. Mind you, that impression is based on a conversation I had with a researcher a year ago who commented that his mentor at a US university rolled out more than 1 start up company every year. As I understand it researchers in Canada may start up one or two companies in their career but never a series of them.

Carbon nanotubes, is exposure ok?

There’s some new research which suggests that carbon nanotubes can be broken down by an enzyme. From the news item on Nanowerk,

A team of Swedish and American scientists has shown for the first time that carbon nanotubes can be broken down by an enzyme – myeloperoxidase (MPO) – found in white blood cells. Their discoveries are presented in Nature Nanotechnology (“Carbon nanotubes degraded by neutrophil myeloperoxidase induce less pulmonary inflammation”) and contradict what was previously believed, that carbon nanotubes are not broken down in the body or in nature. The scientists hope that this new understanding of how MPO converts carbon nanotubes into water and carbon dioxide can be of significance to medicine.

“Previous studies have shown that carbon nanotubes could be used for introducing drugs or other substances into human cells,” says Bengt Fadeel, associate professor at the Swedish medical university Karolinska Institutet. “The problem has been not knowing how to control the breakdown of the nanotubes, which can caused unwanted toxicity and tissue damage. Our study now shows how they can be broken down biologically into harmless components.”

I believe they tested single-walled carbon nanotubes (CNTs) only as the person who wrote the news release seems unaware that mutil-walled CNTs also exist. In any event, this could be very exciting if this research holds up under more testing.

French want more nanotech public debates; British science oral history project

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After last month’s post about disturbances (causing at least one cancellation) taking place during a series of nanotechnology public debates in France, it was a surprise to find that at least one French group wants to continue the ‘discussion’. This last series of  events has been completed with a report due in April 2010. According to a news item on Chemical Watch, France Nature Environnement (FNE) is urging more public debates. From Chemical Watch,

The French public debate on nanotechnologies that began in September ended this week. An official summary of the 17 debates will be published at the end of April, but environmental organisation France Nature Environnement (FNE) says in its conclusions that further discussion is needed to decide where the technology is useful for human advancement and where its use is unacceptable.

You can look at the FNE news item here but it is in French and the site doesn’t seem hospitable to Firefox,  so do try another browser.

Meanwhile, the Brits are embarking on an oral history of British science. From the news item on BBC News,

The British Library has begun a project to create a vast, online oral history and archive of British science.

The three-year project will see 200 British scientists interviewed and their recollections recorded for the audio library.

…

“We have long been painfully aware that there’s a marked absence of significant recordings of scientists,” said Dr Rob Perks, curator of oral history at the British Library.

For instance, said Dr Perks, in the current sound archives there are only two recordings of Ernest Rutherford, none of computer pioneer Alan Turing, hovercraft inventor Christopher Cockerell or AV Hill, a physiologist and Nobel laureate.

A study carried out prior to the project being started found that in the last ten years, 30 leading British scientists including 9 Nobel winners have died leaving little or no archive of their work.

I’m glad to hear that this oral history is being preserved although I do wonder about the recording formats. One of the problems with archiving materials is maintaining to access them afterwards.

Coincidentally, one of the local Vancouver papers (The Georgia Straight) has an article by Rhiannon Coppin (in the Feb. 25 – March 4, 2010 issue) about the City of Vancouver archives and their attempts at digital archiving. From the article,

Every day, Vancouver’s city archivist and director of records and archives runs a rescue operation on our past. Les Mobbs might send out film reels from the ’30s for repair, or he could receive a donation of early-20th-century photographic negatives that need to be catalogued, scanned, and put into cold storage.

Lately, Mobbs has been putting equal consideration into how to preserve our future. More and more of the city’s legal and cultural record is being created in a digital format; in other words, it’s “born digital”, he told the Georgia Straight.

…

The pitfall in digital archiving is that we’re poor caretakers of electronic file formats. In 50 or 100 years, we’ll know we’ve won the preservation game if we can open and read a computer document created today. But even in 2010, we’re missing out on 20-year-old WordStar files stuck on five-and-a-quarter-inch floppy disks. Ironically, it may be safer to keep a paper copy of a document than to store the original computer file.

“We’ve been dealing with paper for 2,000 years,” Mobbs said. “We have a lot of experience with what paper is, what it looks like, and how it’s preserved.”

While acid decay, mould, brittleness, and water damage are formidable but vanquishable foes, machine decay, format obsolescence, and file integrity degradation are virtually unconquerable. The short lifetime of many licensed software formats and the quick deaths of so much hardware (remember LaserDisc?) have posed a particular challenge for archivists like Mobbs.

“How do we preserve material that is, for all intents and purposes, essentially transitory?” he asked.

While this discussion might seem irrelevant on a mostly science-oriented blog, the ‘memristor’ story highlights why information about the past is so important. In 2008, R. Stanley Williams (HP Labs) and his colleagues published two papers, the first proving the existence of a fourth member, a memristor, of electrical engineering’s ‘holy trinity’ of the resistor, capacitor, and inductor and the second paper where they established engineering control over the memristor. Williams  and his team both solved a problem they were experiencing in the lab and made engineering history, in part  by reviewing engineering theories dating back at least 30 years. You can read my post about it here.

Imagine if those theories had been locked into formats that were no longer accessible. That’s one of the major reasons for preserving the past, it can yield important information.

In the interest of full disclosure, I once worked for the City of Vancouver archives.