Tuesday, February 28, 2012

US Patent 8124503 - CNT diameter selection by pretreatment of metal catalysts


This patent from William Marsh Rice University teaches a way to fabricate small diameter (<1nm) carbon nanotubes by modifying catalyst particles prior to CVD growth. Claim 1 reads:

1. A method for producing at least one nanotube, said method comprising the steps of:

placing at least one catalyst particle on a nanotube growth substrate surface;

modifying said at least one catalyst particle; and

growing said at least one nanotube, wherein said step of modifying said at least one catalyst particle comprises modifying the diameter of said at least one catalyst particle, by chemically treating, wherein the chemically treating comprises reducing with a liquid solution.


US Patent 8124044 - Arc discharge synthesis of CNTs


This patent from Sony teaches techniques to improve the purity and diameter uniformity of carbon nanotubes formed via an arc discharge process. Claim 1 reads:

1. A method for preparing carbon nanotubes comprising synthesizing carbon nanotubes from a carbon source using an arc-discharge process in presence of a catalyst and a promoter, wherein the promoter contains an element simple substance capable of reducing a surface energy of carbon nanotubes growth sites in the catalyst, and wherein the promoter is selected from the group consisting of Se, Te, Ge and combinations thereof.


US Patent 8124016 - Antimicrobial article with metal nanoparticles


This patent from LG Electronics teaches an antimicrobial agent for home appliances in which metal nanoparticles are used to improve the effectiveness of sterilization. Claim 1 reads:

1. An article with an antimicrobial property comprising a coating with both Kimchi lactic acid bacteria culture fluid originated from Kimchi lactic acid bacteria and nano metal particles, wherein the nano metal particles are selected from the group consisting of Ag, Zn, Cu, Pt, Cd, Pd, Rh, Cr, and mixtures thereof.


US Patent 8123745 - Ablation catheter with CNT film tip electrode


This patent from Biosense Webster, Inc. takes advantage of the transparent, electrical conductive properties of carbon nanotube films in forming a catheter tip. Claim 1 reads:

1. A catheter, comprising:

a catheter body;

a tip electrode with an optically transmissive shell and a carbon nanotube film on said shell; and

a ring electrode at least partially mounted on the film of the tip electrode, the ring electrode being electrically connected to the film.


Saturday, February 25, 2012

New Scientist screws up reporting on memristor debate

New Scientist recently erroneously reported on an alleged "online spat" regarding memristor papers posted on ArXiv by myself and a group led by Hyongsuk Kim (link). EETimes gave slightly better coverage but still gets it wrong (link).

The subject of the so-called "spat" is whether or not the term "memristor" as originally defined by Leon Chua in 1971 is justifiably applicable to ReRAM, phase change memory, or other forms of 2-terminal memory resistors.

My position is that there is insufficient scientific proof that the memristor as mathematically defined by Leon Chua in 1971 or, as more broadly defined by a 1976 paper by Leon Chua and Sung-Mo Kang, is a correct model for ANY form of ReRAM, phase change memory, or MRAM as claimed by Stan Williams of Hewlett-Packard.

Hyongsuk Kim's position (according to my understanding) is that it is inappropriate to call a device a memristor or memristive system unless it meets certain mathematical criteria regarding invariance of the zero-crossing hysteresis effect when the characteristics of the input signal are changed.

Therefore my position and Kim et al.'s position are not that different (although I believe Kim et al. misunderstands the point of my paper). In addition, there is some evidence from the literature of TiO2 memory resistors that, given Kim et al.'s argument, HP's so-called "memristor" can not be considered a memristor or a memristive system.

This may seem like a mere trivial mathematical argument to some but if the wrong models for ReRAM are being proposed and accepted by the scientific community this will hinder technical progress and innovation in this area resulting in a very negative economic impact if not remedied.

My formal response to Kim et al.'s paper is posted at this link.

Thursday, February 23, 2012

US Patent 8121162 - Nanocrystal laser


This patent from MIT has priority going back to 2001 and includes some broad claims to forming a laser using nanocrystals. Claim 1 reads:

1. A method of forming a laser comprising:

selecting a semiconductor nanocrystal having a diameter and a composition; and

placing the semiconductor nanocrystal on a grating arranged to provide feedback.


US Patent 8120071 - Ionic mem-transistor


This patent from HP applies Leon Chua's concept of memristive systems in the development of a new type of field effect transistor. Some earlier concepts related to memtransistors (i.e. memory transistors) were discussed by Bernard Widrow in the 1960's in terms of a memistor and in a presentation I gave in an IEEE meeting back in 2010 (B.Mouttet, "Memristive systems analysis of 3-terminal devices," ICECS 2010, link). Claim 1 reads:

1. A non-volatile field-effect device, comprising:

a source;

a drain;

a channel-formation portion disposed between and coupled with said source and said drain; and

a memristive gate disposed over said channel-formation portion and coupled with said channel-formation portion;

wherein said memristive gate comprises a plurality of mobile ions and a confinement structure for said plurality of mobile ions; and

said memristive gate is configured to switch said channel-formation portion from a first conductivity state to a second conductivity state in response to migration of said plurality of mobile ions within said confinement structure.


Tuesday, February 21, 2012

US Patent 8119985 - Statistical characterization of nanoparticles


Scanning probe microscopes and electron microscopes are common tools used to study nanoparticles but these instruments are too slow to determine the statistical properties (such as size distribution) of nanoparticle arrays .This patent from FEI Company teaches an new method which may provide more rapid characterization. Claim 1 reads:

1. A method of determining properties of nano-particles, comprising:

forming a charge pattern on a substrate;

distributing nano-particles onto the charge pattern, the charge pattern causing the nano-particles to spread across the surface of the substrate; and

measuring a property of a plurality of nano-particles to determine statistical characteristics of the nano-particle population by:

forming an image of the nano-particle population on the substrate; and

using automated pattern recognition software to find and characterize the nano-particles in which measuring a property of a plurality of nano-particles to determine statistical characteristics of the nano-particle population includes measuring more than 25 nano-particles.


US Patent 8119094 - Carbon nanohorn for fluorine storage


For synthesis of UF6 in uranium enrichment in energy industries, fluorine gas has been used on a mass scale for a long period of time. However, fluorine gas has extremely high reactivity and corrosiveness which makes storage a difficult problem. This patent is based on research from Sumio Iijima (often credited as the discoverer of carbon nanotubes in 1991) and teaches how carbon nanohorns may be useful for storing fluorine gas. Claim 1 reads:

1. A method of taking out fluorine gas by heating a fluorinated carbon nanohorn in a pressure-reduced hydrogen atmosphere of 0.5 kPa or less.

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US Patent 8119093 - C70 fullerene nanotube


This patent from Japan's National Institute for Materials Science claims a new type of nanotube structure based on C70 fullerenes. Claim 1 reads:

1. A C70 nanotube which is a thin line with a hollow structural portion made of a C70 fullerene molecule, wherein a wall thickness of the nanotube is in the range of from 1 to 500 nm, and an outer diameter of the nanotube is in the range from 200 to 1000 nm, wherein an inner diameter of the nanotube is linearly related to the outer diameter of the nanotube throughout the hollow structural portion.


Thursday, February 16, 2012

US Patent 8115189 - Silica nanowire


This patent from Samsung teaches the manufacture of silica nanowires having excellent capacitance and light absorbing properties. Claim 1 reads:

1. A silica nanowire comprising a core portion and an inner region surrounding and contacting the core portion, wherein the core portion comprises a silicon rich oxide and the inner region comprises silicon nanodots.


US Patent 8114937 - Improved conductivity carbon black


This patent from Denka Singapore Private Limited teaches a way to achieve greater electrical conductivity with less carbon using a nanostructured form of carbon black for applications in fuel cells and batteries. Claim 1 reads:

1. A carbon black comprising a chain body which comprises (1) a region of spherical carbon particles and (2) a region of rod-shaped carbon particles, the region (1) and the region (2) being connected.


US Patent 8114807 - Iron palladium nanoparticles


This patent from CEM Corporation involves a new type of nanoparticle catalyst for pharmaceutical synthesis which are reusable, active, can be readily synthesized, and are appropriate for scale-up. Claim 1 reads:

1. A composition comprising:

particles of an intermetallic magnetic compound of iron oxide and palladium having a nanometer particle size; and

wherein at least about 70% by weight of the palladium present in the particles is present on the surface of the nanometer size particles.


US Patent 8114716 - Deletable nanotube circuit


This is one of a series of patents from the company Intellectual Ventures claiming methods of configuring electronic circuits from carbon nanotubes by inactivating unwanted segments of carbon nanotube arrays. Claim 1 reads:

1. A method of constructing a circuit, comprising:

providing an array of carbon nanotubes (CNTs) comprising a plurality of segments, at least a subset of the segments intersecting to form electrically responsive junctions; and

selectively inactivating at least one segment or junction by at least one of (a) applying electromagnetic energy by at least one of (i) directing laser energy toward the at least one segment or junction or (ii) directing an electron beam toward the at least one segment or junction, or (b) chemically attacking the at least one segment or junction.


Wednesday, February 15, 2012

Memresistors on Facebook

I have decided to extend the scope of this blog a little bit. Over the next several years I will be providing more information and analysis regarding the developments of start-up companies and patents related to ReRAM and memresistors (often incorrectly denoted memristors). I will also still be covering the usual nanotechnology patents on this blog. For those only interested in the memresistor information I created a Facebook page which will mirror the memresistor information posted here but exclude the nanotechnology patents. The link to the Facebook page is on the sidebar and below.

Memresistor Facebook Page

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Tuesday, February 14, 2012

US Patent 8114518 - High-purity SWCNT aligned array


This patent is from Japan's National Institute of Advanced Industrial Science and Technology and includes some broad claims with priority going back to 2005 for purified single walled carbon nanotube arrays. Claim 1 reads:

1. A single-walled carbon nanotube having a specific surface area of between 800 m2/g or more and 2500 m2/g or less; and having a purity measured by fluorescence X-rays of 98% or more.


US Patent 8113811 - Manufacturing nanocomposites


This patent from SNU R+DB Foundation (S.Korea) teaches an extrusion apparatus for incorporating carbon nanomaterial into polymer composites. Claim 1 reads:

1. An apparatus comprising:

a barrel configured to accommodate an extrudable raw material;

a shaft rotatably disposed in the barrel;

a motor coupled to the shaft and configured to rotate the shaft to force the raw material through the barrel;

a heater configured to melt at least a portion of the raw material passing through the barrel;

a die coupled to the barrel and including one or more first injectors configured to inject nano-particles into the die, thereby forming at least one layer of the nano-particles over the molten raw material; and

a supply of nanoparticles operably coupled to the one or more first injectors.


US Patent 8113530 - Nano-metal bicycle frame


This patent from PowerMetal Technologies teaches a lighter, stronger, and more durable bicycle formed using a nanostructured metallic coating. Claim 1 reads:

1. A bicycle comprising a frame,

wherein a portion of the frame includes a substrate and a layer of nanostructured material with an average grain size between 2 nm and 5,000 nm extending over at least a portion of the substrate,

wherein a conductive interface is disposed between the substrate and layer of nanostructured material for improved adhesion of the layer of nanostructured material to the substrate and improved impact performance of the frame portion,

wherein the frame portion further includes a silane applied to the conductive interface to improve adhesion of the conductive interface to the substrate.


US Patent 8113437 - Memresistor RFID


There is currently a collaboration between Hewlett Packard and Hynix Semiconductor to produce a ReRAM product by 2013 (which they are incorrectly calling a memristor). This patent may be indicative that the first product may be related to RFID technology. Claim 1 reads:

1. A radio frequency identification (RFID) device comprising:

a radio signal transceiver configured to transmit/receive a radio signal to/from an external reader;

a digital unit configured to detect a command signal from an output of the radio signal transceiver and output a control signal corresponding to the command signal; and

a memory unit that includes a resistive switch device (RSD) having memristor characteristics and that is configured to perform a data read or write operation in response to the control signal and to write data in the resistive switch device depending on a voltage difference between a bit line and a cell plate line,

wherein the resistive switch device is coupled to the bit line and the cell plate line and a voltage level of the cell plate line changes according to a logic state of the data.


Thursday, February 09, 2012

US Patent 8110883 - Electromagnetic sensor using nanotubes


This latest patent from the nanotube electronics pioneer Nantero teaches new applications of their nanotube fabrics in optical sensors. Claim 1 reads:

1. An electromagnetic radiation detector comprising:

a substrate;

a nanotube fabric disposed on the substrate, the nanotube fabric comprising a non-woven network of nanotubes and first and second conductive terminals, each in electrical communication with the nanotube fabric, the first and second conductive terminals disposed in space relation to one another;

wherein the nanotube fabric is tuned and derivitized to be sensitive to a predetermined range of electromagnetic radiation such exposure to the electromagnetic radiation generates a temperature change in the fabric that induces a change in the nanotube fabric resistance between the first and second conductive terminals.


US Patent 8110510 - Low temperature synthesis of nanowires in solution


This patent from Merck Patent GmbH teaches techniques to lower the fabrication temperature of semiconductor nanowires to below 400 C. Claim 1 reads:

1. A method for producing nanowires, comprising:

exposing at least one nanowire precursor to metal nanoparticles in a nanowire growth solution comprising an organic solvent in a non-supercritical state, whereby the metal nanoparticles act as seed particles for the growth of the nanowires,

wherein the nanowires comprise a material selected from the group consisting of (a) Group IV elements, (b) Group II elements other than cadmium, (c) Group VI elements other than tellurium, (d) combinations of a Group III element and a Group V element which include at least one element selected from the group consisting of aluminum and, nitrogen, and (e) GaP.


US Patent 8110476 - Atomic layer carbon memresistor


This patent from SanDisk3D teaches the manufacturing of a new type of carbon-based memresistor based on the deposition of atomic layers using PECVD. Claim 1 reads:

1. A method of forming a memory cell comprising:

forming a steering element above a substrate; and

forming a memory element coupled to the steering element, wherein the memory element comprises a metal-insulator-metal stack comprising a resistivity-switching carbon-based material sandwiched between two conducting layers,

wherein the carbon-based material is disposed above one of the conducting layers, and the other conducting layer is disposed above the carbon-based material, and wherein the carbon-based material has a thickness of not more than ten atomic layers.


Wednesday, February 08, 2012

Memresistor company bought by Rambus

The company Rambus has reportedly bought Unity Semiconductor for $35 million (link). Unity is one of the first companies to innovate in the area of metal oxide RRAM and holds many of the basic patents in this area (link). Hewlett-Packard had attracted much interest in recent years based on relabeling many of the innovations of Unity Semiconductor as a "memristor" and issuing press releases claiming credit for Unity's inventions. I recently debunked the theoretical concept of the memristor in a paper I posted on ArXiv (link).

It is actually somewhat strange to me that Rambus was able to buy Unity. The last I had heard Unity was in a 2 year development deal with Micron Technology (link). My understanding is that Rambus and Micron have a very contentious history. Micron Technology recently won an anti-trust case against Rambus (link) and Rambus has apparently been fighting Micron, Infineon, and Hynix Semiconductor (aka the "Three Amigos") for several years (link). Why would Micron allow Rambus to gain control of Unity especially since HP has been working with Hynix Semiconductor to release metal oxide RRAM in 2013?

In related news Micron CEO Steve Appleton was recently killed in a plane crash (link).  

Tuesday, February 07, 2012

US Patent 8110170 - Manufacturing conductive polymer-CNT composite


Supercritical fluids are substances in which distinct liquid or gas phases do not exist. This patent from SNU R+DB Foundation teaches a method of making carbon nanotube-polymer composites using supercritical fluids which may be applicable to the production of improved sensor and electrode materials. Claim 1 reads:

1. A method of manufacturing a conductive polymer-carbon nanotube composite, comprising the steps of:

introducing a monomer of a conductive polymer into an open-ended carbon nanotube using a supercritical fluid; and

polymerizing the monomer to fill the carbon nanotube with the conductive polymer.


US Patent 8110125 - Separation of carbon nanotubes by density gradients


This patent from Northwestern University has priority going back to 2005 and includes some basic claims to sorting single walled carbon nanotubes between metallic and semiconducting types. Claim 1 reads:

1. A system for separation of single-walled carbon nanotubes, said system comprising:

a fluid medium comprising a density gradient; and

a nanotube composition comprising single-walled carbon nanotubes of mixed nanotube diameters, chiralities, electronic types, or combinations thereof and at least one surface active component.


US Patent 8110026 - Graphene-polymer gas barrier


Gas diffusion barriers are important to some types of chemical processing and sensor applications as well as materials for food packaging. This patent from Princeton University teaches using graphene material to produce improved gas diffusion barriers. Claim 1 reads:

1. A gas diffusion barrier, comprising:

a polymer matrix; and

a functional graphene having a surface area of from about 300 m2/g to 2600 m2/g,

wherein said functional graphene is made by thermally exfoliating graphite oxide at a temperature of from 300 to 2000° C.


US Patent 8109129 - Portable nanoparticle size classifier


Naneum Limited is a company founded in 2005 with the aim of developing and marketing easy to use instruments for detecting and characterizing airborne nanoparticles. This patent from Naneum teaches handheld instrumentation to classify nanoparticles according to size. Claim 1 reads:

1. A nanoparticle size classifier comprising a variable flow rate system, wherein the variable flow rate system comprises:

a diffusion cell having a single diffusion element disposed therein, the diffusion cell having an inlet and an outlet;

a flow meter;

a pump; and

a pump controller for controlling variable flow rates within the variable flow rate system;

wherein the variable flow rate system is arranged to enable a plurality of particle number concentration measurements to be obtained by passing an aerosol through the diffusion element at various flow rates.


Thursday, February 02, 2012

HP's memristor delusion

Recently EETimes (link)  has picked up on e-mail correspondences I have had with a few industry scientists regarding HP's so-called "memristor." I had recently posted an article on ArXiv debunking the mathematical basis for Leon Chua's memristor theory from the 1970's.  HP is using the memristor theory to claim credit for a new form of non-volatile memory called RRAM which is under development by Panasonic, Toshiba, Sharp, Unity Semiconductor, and a variety of other companies. It turns out that many of the scientists involved in legitimate research in RRAM view HP's memristor as a foolish gimmick which is being perpetuated by naive academics and science writers.

The story behind the memristor delusion is actually quite interesting and I went into more detail in a paper I posted on scribd available at this link. The article directly addresses public comments made by Stan Williams, one of the lead researchers of HP.  The article also points out some evidence of plagarism in HP's original 2008 Nature paper based on an earlier patent application of Samsung and a paper published in 1968 on resistance switching in titanium oxide thin films.