Friday, June 27, 2008

US Patent 7391235 - Mem-resistor crossbar signal processor

There has been some interest recently in "memristors" which have been noted as representing a fourth fundamental circuit component after resistors, capacitors, and inductors. While the recent interest stems from the discovery by Hewlett-Packard researchers of bilayer oxides as a new type of memristor material for their nanoscale crossbar arrays a variety of other materials including chalcogenides, perovskites, and semiconducting polymers have been used over the past several decades having similar memory resistance properties and which form the basis of several proposals for RRAM being pursued by a variety of companies including Micron Technologies, Samsung, and Unity Semiconductor. While most proposed applications of memristor type material have been in non-volatile memory this patent teaches a variety of circuit configurations in which programmable resistances in a crossbar array are used in combination with operational amplifier circuitry for signal processing applications such as waveform generation, programmable filters, communication switching, and pattern analysis. Claim 1 reads:

1. A device comprising:

a crossbar array including a programmable impedance layer and having crosspoint impedances Zij;

an array of input impedances Zin(i) electrically connected to input columns of the crossbar array; and

an array of op-amps electrically connected to outputs rows of the crossbar array wherein each of the op-amps include a feedback impedance Zout(j) connected between an output terminal and an inverting input of the op-amp, wherein the crossbar array, the array of input impedances, and the array of op-amps are configured to produce a matrix transformation T(i,j), based on the impedances Zin(i), Zij, and Zout(j), for combining input signals.

Thursday, June 26, 2008

US Patent 7391144 - Field emission particles with embedded carbon nanomaterials

A variety of carbon based nanomaterials such as carbon nanotubes and nanocrystalline diamond have been experimented with over the past few years as field emission material for applications such as flat-panel displays. In order to further enhance the efficiency this patent from Samsung teaches using particles in which the CNTs may be partially embedded to maximize the exposure of the CNT tips during emission. Claim 1 reads:

1. A carbon-based composite particle for an electron emission source, comprising:

a particle comprising a material selected from the group consisting of metals, oxides, ceramic materials, and combinations thereof; and

a carbon-based material which is partially embedded within the particle and which partially protrudes from the surface of the particle.


US Patent 7390568 - Exciton separation with core/shell nanocrystals

Excitons are formed from bound states of electrons and holes in insulating and semiconducting materials and are often involved in applications involving light sensing, light emission, and photovoltaics. This patent from M.I.T. teaches forming coated nanocrystals in which excitons can be bound via the core and shell of the nanocrystal. Claim 1 reads:

1. A method of preparing a coated nanocrystal comprising:

introducing a core nanocrystal including a first semiconductor material into an overcoating reaction mixture; and

overcoating a second semiconductor material on the core nanocrystal, wherein the first semiconductor material and the second semiconductor material are selected so that, upon excitation of the nanocrystal to form an exciton, one charge carrier of the exciton is substantially confined to the core and the other charge carrier of the exciton is substantially confined to the overcoating.


Wednesday, June 25, 2008

US Patent 7390477 - High purity nanotube compositions

This patent originating from Richard Smalley's group at Rice University is a continuation patent based on earlier patents with priority going back to 1997. These earlier patents were mostly focused on single walled carbon nanotubes, however this patent seems to broaden the scope to include a wider variety of nanotube types (multiwalled carbon nanotubes and perhaps even fullerene-like nanotubes formed from non-carbon materials such as boron nitride). Since multiwalled nanotubes may be easier to produce and useful as field emission material for displays, thermally conductive material for heat sinks, and electrically conductive material for flexible electrodes this patent may be particularly significant. Claim 1 reads:

1. A composition of matter comprising at least about 99% by weight of fullerene nanotubes.


US Patent 7390343 - Nanoalumina fiber water filter

This patent from Argonide Nanomaterials teaches a water filter that uses fibrous nanoalumina materials for higher efficiency contamination adsorption. Claim 1 reads:

1. A filtration device, said filtration device comprising at least one cartridge, each said cartridge having a support member that supports at least one fibrous structure, each said fibrous structure comprising nano alumina fibers and second fibers mixed with said nano alumina fibers, wherein said second fibers are arranged to create asymmetric pores.


Tuesday, June 24, 2008

US Patent 7389679 - Micromechanical cantilever measurement cell with gas bubble absorption

The change of resonance in micromechanical cantilevers is used to detect biological material in chemical cells however the presence of air bubbles sticking to the cantilever can disrupt this detection. This patent teaches providing a gas volume within the measurement cell to prevent such problems. Claim 1 reads:

1. A measurement cell for an arrangement for the analysis of liquids, comprising, integrated into a single cell:

at least one inlet and at least one outlet for the analyte liquid,

a gas volume for the absorption of gas bubbles present inside the analyte liquid, said gas volume being located within said single cell and sealed from the environment,

at least one micromechanical cantilever, which is at least partially located inside the measurement cell and is at least partially in contact with the analyte liquid.


US Patent 7389671 - Ultrafast palladium nanocluster sensor

Hydrogen sensor are an important component in many fuel cell and internal combustion engine designs but can suffer from slow response times ranging from seconds to minutes. This patent teaches the use of palladium nanoclustors formed on a low stiction interface material (siloxane) to form a more high speed reaction time for hydrogen sensing. Claim 1 reads:

1. A hydrogen detector, comprising:

a non-conducting substrate having mobile Pd or Pd alloy nanoclusters forming a film on said substrate, said film being on the threshold of percolation;

a mechanism electrically connected to said Pd or Pd alloy film for sensing a change in electrical resistance in response to the presence of hydrogen in contact with said Pd or Pd alloy film;

whereby as hydrogen is absorbed by said Pd or Pd alloy nanoclusters they swell resulting in an increase in the conductivity thereof and wherein said non-conducting substrate has a stiction-reducing coating thereon.


Friday, June 20, 2008

US Patent 7388200 - Nanobiosensor with residence time measurement

This patent from Hewlett Packard teaches tailoring the absorption and desorption characteristics of a nanosensor in order to use the amount of time in which a chemical resides in the nanosensor to characterize the chemical. Claim 18 reads:

18. A nanosensing system, comprising at least one nano-transducer having a controlled surface, the nano-transducer being configured to transduce adsorption and desorption of at least one species to a measurable signal as a function of time, wherein the adsorption and desorption each define an individual measurable event and wherein a residence time of the at least one species adsorbed on the nano-transducer is extractable from the measurable signals.


Tuesday, June 17, 2008

US Patent 7388199 - Nanotube scanning probe tip with contamination film removal

In order to inspect high aspect ratio structures on the nanometer scale with reliability carbon nanotubes have been used as the tips of atomic force microscopes. In order to increase the conductivity and bonding strength of the nanotubes to the AFMs this patent teaches a removal of a contamination film formed during the connection of the nanotube to the AFM. Claim 1 reads:

1. A method of producing a probe comprised of a nanotube, a base holding the nanotube, and a bonding means for bonding said nanotube to said base, which method comprises performing attaching of said nanotube and said base under observation by an observing means and, at a stage before bonding by said bonding means, stripping a contamination film formed by said observing means.

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US Patent 7387735 - Acidic solution for isolating semiconductor CNTs

This patent from Samsung teaches a new method for isolating semiconducting single walled carbon nanotubes using a mixture of nitric and sulfuric acids. Claim 1 reads:

1. A method of isolating semiconducting carbon nanotubes, comprising:

mixing carbon nanotubes with a mixed acid solution of nitric acid and sulfuric acid to obtain a carbon nanotube dispersion; stirring the carbon nanotube dispersion at room temperature; and

filtering the carbon nanotube dispersion; wherein a volume ratio of nitric acid: sulfuric acid in the mixed acid solution is in the range of about 1:9 to about 2:8.


Wednesday, June 11, 2008

US Patent 7385267 - Microfluid nanowire sensor

This patent from Harvard with relatively early priority (Dec. 11, 2000) may lay claim to the basic use of nanowires or nanotubes for chemical sensing of small fluid volumes. Claims 1 and 25 read:

1. A method comprising: providing a nanowire and contacting the nanowire with a sample having a volume of less than about 10 microliters; and measuring a change in a property of the nanowire resultant from the contact.

25. An article comprising: a sample cassette comprising a sample exposure region and a nanowire, at least a portion of which is addressable by a sample in the sample exposure region, wherein the sample cassette is operatively connectable to a detector apparatus able to determine a property associated with the nanowire.


US Patent 7385266 - Vertical CNT sensor

Careful alignment of carbon nanotubes between electrodes is often necessary to construct electronic devices with carbon nanotubes. However, the proper positioning of the nanotubes is a difficult problem for large scale production. This patent from Nantero teaches a chemical sensor platform based on vertically oriented nanotubes which can be easier to directly fabricate on patterned electrode structures. Claim 1 reads:

1. A sensor platform, comprising:

a sensor element comprising at least one nanotube and having an electrical characterization;

a support structure, comprising a substrate, for supporting the sensor element so that it may be exposed to a fluid, and having a major surface of the substrate substantially non-parallel to the sensor element; and

control circuitry to electrically sense the electrical characterization of the sensor element so that the presence of a corresponding analyte may be detected, wherein the sensor element has an affinity for the corresponding analyte, and wherein the sensor element comprises a pristine nanotube.


Tuesday, June 10, 2008

US Patent 7384815 - Attaching molecular wires to carbon nanotubes

This patent from Rice University is fairly basic to the use of carbon nanotubes as components of molecular electronics devices. Claim 1 reads:

1. A process comprising: (a) derivatizing a carbon nanotube with a diazonium specie; and (b) covalently attaching a molecular wire to the derivatized carbon nanotube.


US Patent 7384680 - Inorganic nanopowder film

This patent from a company called Nanogram is fairly basic to inorganic nanopowder thin films which may be important to future printable electronics and optics applications. Claim 1 reads:

1. A substrate comprising a powder coating comprising an inorganic composition, the powder coating comprising primary particles having an average particle size less than about 500 nm and effectively no primary particles having a diameter greater than about 4 times the average primary particle diameter wherein the powder coating has an approximately uniform thickness across at least a portion of a substrate surface and wherein the powder coating forms a porous network of fused inorganic particles wherein the powder coating has a thickness from about 50 nm to about 500 microns.


Monday, June 09, 2008

US Patent 7381950 - Semiconductor height profiling using SPM

This patent from Texas instruments (priority 9/24/2004) includes some basic claims to use a scanning probe microscope to measure the height of semiconductor structures. Claim 1 reads:

1. A method comprising characterizing the physical height of structures on a semiconductor device having dimensions less than approximately 100 nanometers (nm) using a probe of one of scanning probe microscopy (SPM) and profilometry by determining the difference in height between the probe of one of a SPM and profilometer at a reference position to the probe at a second position.

However, some prior art may have been overlooked such as US Patent 6,816,806 (see for example column 7, lines 10-25).


US Patent 7381686 - Metal nanoparticle composite for inhibiting algae growth

This patent is directed to composites for water purification and teaches a nanoparticulate silver composition to inhibit algae growth. Claim 1 reads:

1. A composite for inhibiting algae growth in water comprising a polypore base carrier and a nano-metal mixture coated on the carrier, wherein the mixture comprising a nano-silver particle and a nano-zinc oxide for fixing the particle on the carrier, and tourmaline, wherein said composite is sufficient to inhibit said algae growth, and convert the water from green to colorless in appearance.

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US Patent 7381461 - Zeolite nanocrystal antireflective film

In order to prevent glare for displays and other optical devices anti-reflective films are often used. These anti-reflective films usually employ either multilayer films having thicknesses selected for destructive interference of any reflection or films having a graded index of refraction to achieve the same effect. This patent teaches an alternative solution using graded porosity of a zeolite nanocrystal film. Claim 1 reads:

1. An antireflective transparent zeolite hardcoat, comprising a zeolite nanostructure made of zeolite nanocrystals vertically stacked into a porous structure on a substrate, wherein the porosity increases with structure height, thereby providing a smooth refractive index transition.

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Friday, June 06, 2008

US Patent 7381983 - N-type carbon nanotube field effect transistor

In order to create CMOS structures in electronics both p-type and n-type transistors are required. For carbon nanotube transistors n-type doping have been difficult to construct. This patent from Samsung teaches a carbon nanotube field effect transistor in which the carbon nanotube semiconductor junction is n-doped via the inclusion of an electron donor material such as bismuth titanium silicon oxide to contribute a type V material (e.g. bismuth) to achieve an n-type transistor.

1. An n-type carbon nanotube field effect transistor (CNT FET) comprising:

a substrate;

electrodes formed on the substrate and separated from each other;

a CNT formed on the substrate and electrically connected to the electrodes;

a gate oxide layer formed on the CNT; and

a gate electrode formed on the gate oxide layer, wherein the gate oxide layer contains electron donor atoms which donate electrons to the CNT such that the CNT is n-doped by the electron donor atoms.


US Patent 7381465 - Etchable core nanoparticle surrounded by non-etchable shell

In order to promote chemical reactions often porous materials such as zeolites are used in applications such as water purification and crude oil processing. To improve the reactivity of some reactions it has been proposed to arrange nanopores close to catalytic nanoparticles. This patent from Japan Science and Technology Agency teaches a new type of material with an photoetchable nanoparticle (such as CdS) surround by SiO films resistant to photoetching and to create a void within the CdS. Claim 1 reads:

1. A core-shell structure having a void space of predetermined size inside a shell, comprising:

a core comprising nanoparticles, said core is a photoetchable solid;

a shell coating said core, said shell is a non-photoetchable material; and

a void space defined by a space between said core and said shell, wherein said predetermined size of said void space is 1 nm to about 50 nm in diameter.


Tuesday, June 03, 2008

US Patent 7381625 - Deterministic nanodevice construction using AFM

The use of scanning tunneling microscopes and atomic force microscopes to position atomic and molecular structures goes back to work done by Don Eigler of IBM in the late 1980's. This patent from Michigan State University teaches a modification of these methods which scratches an electrode into two portions using an AFM tip and using the tip to position nanostructures such as carbon nanotubes between the electrodes. Claim 1 reads:

1. A method for constructing a nanodevice, comprising:

fabricating an electrode structure on a substrate surface;

forming a nanogap across the electrode structure, thereby forming a pair of electrodes;

dispersing a plurality of nanoobjects onto the substrate surface using electrophoresis; and

positioning one of the nanoobjects in relation to the pair of electrodes using a tip of an atomic force microscope, wherein the one nanoobject connects one of the electrodes to the other electrode.


US Patent 7381316 - CNT positioning using AC+DC field

This patent from Northwestern University teaches an interesting positioning and alignment method for placing a carbon nanotube between electrodes. An ac field is used to attract the nanotube to the electrodes while a dc field provides the orientation of the nanotube with respect to the electrodes. Claim 1 reads:

1. A method of depositing a carbon nanotube, said method comprising:

providing a first electrode at a distance from a second electrode, said electrodes on a substrate and comprising a first electrode pair;

introducing at least one carbon nanotube proximate said electrodes; and

generating a composite electric field between said electrodes, said field having an ac electric field component and a dc electric field component, said composite electric field depositing a carbon nanotube across said electrode pair.