US Patent 8110125 - Separation of carbon nanotubes by density gradients

http://www.freepatentsonline.com/8110125.html

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 7997123 - Microfabricated DPN®

http://www.freepatentsonline.com/7997123.html

This patent from Northwestern University teaches a manufacturing method for Dip-Pen Nanolithography® allowing for a high density 2D array of fluid dispensing microtips to be integrated on a microfluidic chip. Claim 1 reads:

1. A device, comprising a tip having a pointed tip body and an annular shell comprising an etched thin film spaced about the tip body to define an annular empty space about the tip body wherein a semiconductor chip substrate or another thin film defines the tip body.

US Patent 7954166 - Independently addressable DPN arrays

http://www.freepatentsonline.com/7954166.html

This latest patent from the founders of NanoInk teaches methods to prevent cross-contamination between arrays of Dip Pen Nanolithography (R) tips. Claim 1 reads:

1. A method comprising:

providing at least one array of tips;

providing at least two patterning compositions different from each other;

ink jet printing at least two of the different patterning compositions onto at least some of the tips; and depositing at least some of the ink jet printed patterning compositions onto a substrate surface;

wherein the array of tips and the ink jet printing are adapted to prevent substantial cross-contamination of the patterning composition on the tips.

US Patent 7887885 - Molecular resist removal with DPN

http://www.freepatentsonline.com/7887885.html

This patent teaches a variation of Dip Pen Lithography® in which the scanning probe tip removes a portion of molecular resist during coating. Claim 1 reads:

1. A method of nano lithography comprising:

providing a substrate;

coating at least a portion of the substrate with a resist;

providing a tip with a drop of patterning compound on the tip;

applying the tip to a portion of the substrate coated with the resist wherein a high normal force is formed between the tip and the substrate by the surface tension of the drop of patterning compound on the tip that forms a thin film of the patterning compound on the substrate in an area proximate the tip; and,

moving the tip to remove resist from the substrate, whereupon the patterning compound attaches to the substrate from which the resist has been removed by the tip to form a pattern of the patterning compound on the substrate.

US Patent 7811635 - Nanoink with inorganic precursor

http://ip.com/patent/US7811635

This latest patent from the founders of NanoInk (priority 2001) broadly covers the deposition of reactive sol-gel "inks" used in their Dip Pen Nanolithography(R) process. Claim 1 reads:

1. A method of fabricating inorganic/organic nanostructures comprising depositing an ink on a substrate by direct write nanolithography with a tip to form a deposit, wherein the ink comprises an inorganic precursor and at least one organic polymer.

US Patent 7744963 - Driving Dip Pen Nanolithography® with electric or magnetic force

http://www.freepatentsonline.com/7744963.html

This patent from Northwestern University has priority going back to 2001 and appears basic to a driving method used by NanoInk in Dip Pen Nanolithography®. Claim 1 reads:

1. A method of nanolithography, comprising:

providing a substrate;

providing a tip comprising an internal cavity having an external opening to the surface of said tip, wherein said opening comprises an internal diameter of less than about 200 nanometers;

loading said cavity with a deposition compound, wherein said deposition compound does not pass through said external opening in the absence of a driving force; and

subjecting said tip to a driving force to deliver said deposition compound through said external opening to be deposited on said substrate;

wherein the driving force is selected from the group consisting of an electrical and a magnetic driving force, wherein, for the electrical driving force, the deposition compound is a charged compound subjected to an applied electric field, and wherein, for the magnetic driving force, the deposition compound is a magnetic compound or a magnetically tagged compound subjected to a magnetic field.

US Patent 7662298 - Density gradient separation of CNTs

http://www.freepatentsonline.com/7662298.html

This patent is from Northwestern University and teaches a technique called density gradient ultracentrifugation allowing for segregation of single walled carbon nanotubes based on their bandgap. An article on the process is available here. Claim 1 reads:

1. A method of using a density gradient to separate single-walled carbon nanotubes, said method comprising:

centrifuging a nanotube composition in contact with a fluid medium comprising a density gradient; and

separating the nanotube composition into two or more separation fractions,

wherein said nanotube composition comprises single-walled carbon nanotubes of mixed nanotube diameters, chiralities, electronic types, or combinations thereof and at least one surface active component; and

at least one of said two or more separation fractions is enriched with single-walled carbon nanotubes of a selected nanotube diameter, chirality, electronic type, or combinations thereof relative to the nanotube composition.

US Patent 7611562 - Triangular nanoframes

http://www.freepatentsonline.com/7611562.html

This patent comes from Chad Mirkin's group at Northwestern University. The patent teaches methodology used to fabricate a new type of nanostructure called a "nanoframe" which is useful to investigating how nanoscale shapes effect the bulk physical and chemical properties of substances. Claim 1 reads:

1. A method of forming a triangular nanoframe comprising etching a nanoprism with a salt to form a nanotriangle.

US Patent 7466406 - Nanodisk array nanowire assaying

http://www.freepatentsonline.com/7466406.html

This patent from Northwestern University discloses an interesting modification of nanowires used in SERS in which nanodisk arrays are etched out of the nanowire to serve as substrates for an analyte allowing for tuning of nanowires for analytes of interest. Claim 1 reads:

1. A method of assaying for a presence or a concentration of an analyte or a plurality of analytes in a sample comprising:

a) contacting the sample with a nanowire to create a mixture, wherein the nanowire comprises at least one nanodisk array comprising at least two nanodisks, each nanodisk independently having a thickness of about 20 nm to about 500 nm, and at least one gap of about 2 to about 500 nm;

b) illuminating the mixture with a radiation source; and

c) measuring a signal intensity resulting from the illumination of the mixture, wherein the intensity is correlated to the presence or concentration of the analyte in the sample.

US Patent 7381316 - CNT positioning using AC+DC field

http://www.freepatentsonline.com/7381316.html

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.