Thursday, December 28, 2006

Alternative Nanoelectronics: A Comparative Analysis

I recently published an article in the latest issue of Nanotechnology Law & Business Journal (see link) profiling four of the leading companies in alternative approaches to nanoelectronics - D-Wave, Hewlett-Packard, Nanosys, and Nantero. Each of these companies is exploring a different platform providing new paradigms and potential for completely new applications of electronics.

US Patent 7155343 - Nanocircuits and Embedded Circuits

It is common to combine sensing devices with electronic circuitry and memory devices for a variety of applications in "smart" devices. However, conventionally the sensor, circuitry and memory are incorporated in a circuit package. This patent suggests instead embedding nanoelectronic components in a spreadable medium such as paint, cement, or dye to coat walls, clothing, windows, etc. and provide an environmental sensing and recording array. Claim 1 reads:

1. A method for detecting environmental analog data comprising: providing a plurality of sensors, each sensor comprising an input, an analog to digital converter, a timer, memory, an output and a power source, said input detecting analog data, converting said analog data to digital data, said timer signaling the time to record data, said memory storing the input and the time the data was recorded, and said output transmitting digital data upon request; providing a spreadable medium; embedding a plurality of nanocircuits in said spreadable medium; and associating said spreadable medium with a surface.

A similar idea was earlier proposed by Boeing which uses RFID tags embedded in paint.

US Patent 7153703 - Nanoparticle with Dendron Ligand Coating

Nanocrystals have very useful optical properties which can be tuned according to their size. However, they are also subject to oxidation that can hinder these optical properties. This patent from the University of Arkansas teaches using dendron ligands (hyper branched organic molecules) to avoid such oxidation. Claim 1 reads:

1. A nanoparticle composition comprising: a nanoparticle coated with a plurality of dendron ligands covalently bound to a surface of the nanoparticle.

Wednesday, December 27, 2006

US Patent 7153597 - Nanoparticle Magnetic Memory

For data storage densities approaching the a Terabit/in2 nanoparticle magnetic material are usefully applied to suppress noise over more conventional magnetic recording media. In order to pattern such nanoparticles in an ordered array so as to be useful for magnetic storage this patent employs a self-assembled monolayer deposited in segmented pits. Claim 1 reads:

1. A device for magnetic recording comprising: a substrate having a locking pattern formed therein, the locking pattern comprising a plurality of pits formed in the substrate; a self-assembled monolayer (SAM) deposited on the substrate in the plurality of pits; and a first layer of nanoparticles deposited on the SAM in the plurality of pits and chemically bonded to the substrate via the SAM.

US Patent 7153452 - Carbon Nanotube Re-enforced Carbon Fiber

Carbon fiber materials are lightweight, durable, and possess high strength. However, minute flaws can reduce these qualities. This patent teaches providing a fractional percentage of carbon nanotubes to prevent such flaws during manufacture. Claim 1 reads:

1. A modified, mesophase pitch-based carbon fiber comprising from about 0.05 percent to about 1.0 percent by weight of carbon nanomaterial reinforcements.

Tuesday, December 26, 2006

US Patent 7152474 - MEMS Asymmetry Self-test

Microdevices such as accelerometers may exhibit improper operation over time due to asymmetries of manufacture or environmental effects. Due to the small size of such devices it is difficult to provide external means to reliably detect such improper operation. This patent from Carnegie Mellon University proposes building in an intrinsic sensing system to detect asymmetries in the microdevice to easily provide data whether the microdevice needs to be replaced or alternatively to provide self correcting signals for driving the microdevice. Claim 1 reads:

1. In a MEMS device, the improvement comprising: a plurality of sensors electrically isolated from one another and positioned about an axis of symmetry to produce signals of substantially identical characteristics; and circuitry responsive to said plurality of sensors for comparing said signals produced by said plurality of sensors to identify asymmetries in said MEMS device.

US Patent 7151256 - Nanostructured Tip Array on a Cantilever

Scanning Probe Microscopes were developed in the early 1980's to detect matter on the atomic level. Recently there has been much interest in using nanotubes and other high aspect ratio materials as the tips for the microscopes. This patent from UT-Battelle proposes that forming a vertically aligned tip on a cantilever as a new idea. Claim 24 reads:

24. An apparatus, comprising a cantilever structure including: a substrate including a cantilever body; and a substantially vertically aligned, with respect to a plane of the cantilever body, elongated nanostructure coupled to the cantilever body.

Unfortunately the Examiner seems to have missed applicable prior art such as:


Monday, December 25, 2006

US Patent 7151209 - Etch and Release of Nanostructures

Using materials with differential etch rates is a common technique to release microstructural elements such as cantilevers or membranes from a substrate. This patent from Nanosys alleges that applying this technique on the nanoscale to release nanostructures from a substrate is a new idea. Claim 1 reads:

1. A method of harvesting a nanostructure from a substrate, the nanostructure comprising at least a first region comprising a first material and a second region comprising a second material, wherein the first material is differentially etchable from the second material, the method comprising etching away the first material of the nanostructure to release the nanostructure from the substrate at the first region.

Unfortunately the Examiner seems to have missed this patent from Agere Systems
which may have some prior art relevance.

Friday, December 22, 2006

US Patent 7150910 - Nanocrystal Grating

One of the promising applications of nanocrystals derives from their size dependent band gaps which can produce optical amplification effects useful for lasers. This patent from M.I.T. teaches nanocrystals arranged with a particular periodicity to optimize such amplification effects. Claim 1 reads:

1. A structure comprising: a grating having a periodicity from 200 nm to 500 nm; and a semiconductor nanocrystal layer disposed on the grating, the layer including a plurality of semiconductor nanocrystals.

US Patent 7150865 - Semiconductor Nanotube Enhancement Using Microwaves

Several techniques have been proposed to seperate semiconducting from metallic nanotubes. The approach of this patent takes advantage of the sensitivity of metallic nanotubes to microwaves to damage or destroy the metallic type and leave the semiconducting type. Claim 1 reads:

1. A method for processing carbon nanotubes comprising: receiving a carbon nanotube sample composed of metallic-type and semiconducting-type nanotubes; positioning said carbon nanotube sample in a microwave cavity at a location corresponding to a maximum in the electric field of a stationary wave having a first microwave frequency; and exposing said carbon nanotube sample to a stationary wave having said first microwave frequency and a first power, wherein proportion of semiconducting-type carbon nanotubes in the sample is increased.

Tuesday, December 19, 2006

US Patent 7150864 - Single Walled / Double Walled Nanotube Rope

Based on research initially conducted by Richard Smalley and others at Rice University, high purity single walled carbon nanotubes can be fabricated. This patent presents some broad claims to the product of such manufacture including both single and double walled nanotubes. Claim 1 reads:

1. A rope of carbon nanotubes comprising single-wall and double-wall carbon nanotubes.

US Patent 7150863 - Indene Based Fullerene Fabrication

In the search for cheaper manufacturing methods for fullerene material such as buckyballs and nanotubes combustion based methods have been explored. This patent claims the use of Indene (C9H8) in such combustion processes. Claim 1 reads:

1. A method for making fullerenes or other carbon nanomaterials which comprises the steps of: (a) burning a multiple-ring aromatic hydrocarbon fuel comprising indene; and (b) collecting condensables containing carbon nanomaterials produced by burning the multiple-ring aromatic hydrocarbon fuel.

US Patent 7148619 - Carbon Nanotube Between Two Electrodes

This patent from Canon is in the top three broadest nanotube patents I've seen (IBM's single walled nanotube patent and Till Keesman's electron emitting nanotube patent being the other two). Canon evidently thinks it invented placing a nanotube between two electrodes in 1997 (patent claims foreign priority to Oct. 30 1997). Claim 1 reads:

1. An electronic device comprising: (i) a first and a second electrodes; and (ii) a carbon nanotube electrically connecting the electrodes.

The inventor, attorney, examiner, etc. missed several pertinent technical references which I believe would clearly anticipate this and other claims of the patent. For example, in 1994 an article was published entitled "Measurements of the conductivity of individual 10 nm carbon nanotubes" by the Materials Research Society based on the proceddings of the 1994 spring meeting. The abstract of the talk is as follows:

Catalytically grown carbon fibers approximately 10 nm in diameter and several microns long were characterized by transmission electron microscopy and determined to be multiple-walled nanotubes, and a technique was developed to measure the conductivity of an individual nanotube. Nanotubes were dispersed in solvents and precipitated onto lithographically defined gold contacts to make a `nano-wire' circuit. Non-contact AFM was used to image the nano-wires, and a resistance of 11.4 (±1.0) MΩ was measured through a single nanotube at 23 °C. A resistivity of 9.5×10-5 Ωm was estimated for carbon conducting along the axis of a fiber. Local heating of nanotubes appeared to occur at high current densities. The nanotubes could sustain currents on the order of 10 μA per fiber, but application of currents on the order of 100 μA per fiber resulted in rapid decomposition in air and breaking of the circuit.

Also see "Individual single-wall carbon nanotubes as quantum wires" in Nature 386, 474 - 477 (03 April 1997)

Sunday, December 17, 2006

US Patent 7148579 - Thermoelectric Generator Using Nanostructures

This patent from Ambient deals with the conversion of energy from the motion of individual molecules into a usable energy output. Typical thermoelectric generators use the energy generated by a cumulative output of a large number of molecules but most devices are too course to make use of individual molecules. Claim 1 reads:

1. An energy conversion and regulation system comprising: a base member; a system output; a plurality of parallel arrays, wherein at least two of said plurality of parallel arrays are electrically connected in series, each one of said plurality of parallel arrays comprising: a plurality of generator-switch assemblies electrically connected in parallel and electrically connected to said system output, wherein each of generator-switch assemblies comprises: a generator coupled to said base member that converts thermal energy into a time-varying electrical signal; and a nanometer-scale switch coupled to said base member, wherein said switch is electrically connected in series with said generator such that said switch automatically closes in reaction to said time-varying electrical signal having at least a minimum non-zero magnitude.

US Patent 7147966 - Conducting Polymer Coating For Nanotube Array

Intensive study of conducting polymers began in the 1970's and has resulted in several applications in batteries, sensors, and electrochromic displays. As taught by this patent, forming such conducting polymers as surface coatings to nanotube arrays allows for further applications in batteries and fuel cells with greater charge retention characteristics. Claim 1 reads:

1. A conductive carbon nanotube electrode material comprising: a porous carbon nanotube substrate comprising a plurality of longitudinally aligned linear carbon nanotubules in a three-dimensional array; and a uniform surface coating comprising an electrically conducting polymer present as a film on an entire surface and length of individual nanotubules establishing electrical continuity by producing continuous contact throughout the three-dimensional array and cohesively holding together the nanotubules in the three-dimensional array.

Thursday, December 14, 2006

US Patent 7147834 - Perovskite Nanotube

While carbon nanotubes are currently the dominant nanostructure of interest there is a persistant push to find alternative nanostructures. This patent from the State University of New York teaches the formation of nanotubes formed of perovskite (e.g. SrTiO3, BaTiO3) material. Claim 1 reads:

1. A monophasic perovskite nanotube having an outer diameter from about 1 nm to about 500 nm and a length from about 10 nm to about 10 microns.

US Patent 7147831 - Bending Nanotube Array

Growth of vertically oriented nanotube arrays is often performed using a catalytic layer formed on a substrate. However, in order to form more complex structures it would be useful to have the nanotubes formed horizontally or at an angle to the substrate surface so that the nanotubes could be connected at two rather than just one end. This patent is based on collaborative work between a Chinese university and a Taiwanese company and proposes the use of a nonuniform catalytic film so as to create a bending array of nanotubes. Claim 1 reads:

1. An apparatus comprising: a substrate; a catalyst layer disposed on the substrate, the catalyst layer comprising a plurality of nano-sized catalyst particles, sizes of the catalyst particles decreasing along a given direction; and an array of aligned carbon nanotubes extending from the catalyst layer in an arc toward the given direction, a respective length of each carbon nanotube being in proportion to the size of the catalyst particle from which such a nanotube is grown.

Google Patents

Google has recently come up with a unique and very useful search tool for free patent searching. It seems very user friendly and should make finding information on patented technology much easier.

Tuesday, December 12, 2006

US Patent 7147726 - Nanoparticle Fabrication Using Ball Impact

The typical methods for nanoparticle fabrication include a variety of chemical processes usually involving catalytic materials, high temperatures and specialized processing steps. The method proposed by this patent instead employs a mechanical mechanism based on agitation of ball bearings to mill a metal target in order to generate a nanostructured layer on the target. Claim 3 reads:

3. A mechanical device for generating nanostructures in a metal piece comprising at least one chamber that is closed for the size of the balls containing a given quantity of perfectly spherical balls of given dimensions, means for linking the chamber with means for generating a vibration communicated to the chamber, the assembly of the chamber and vibrating means being mounted on shock absorbing means on a plate adapted to be rotated at a given speed.

US Patent 7147692 - Nanoparticles for Air Cleaning

There has been discussion in some circles about possible adverse environmental effects of nanoparticulate matter. However, this patent from Procter & Gamble looks to the high surface to volume ratio characteristics of nanoparticles to assist in air purification. Claim 1 reads:

1. A method for cleaning indoor air comprising contacting the air with an aqueous or non-aqueous liquid through a packed column scrubber comprising a photobleaching agent with nanoparticles dispersed therein in a stand-alone apparatus.

Sunday, December 10, 2006

US Patent 7145614 - Nanocrystal Color Filter

Conventional reflective color displays can suffer from inefficiency of light reflection due to light passing through color filters twice (once on entry and once on exit). This patent from Samsung proposes the use of nanoparticles of varying sizes to regulate the reflected color and avoid the use of a separate filter. Claim 1 reads:

1. A reflective display device using photonic crystals, comprising: a plurality of reflective color filters, each reflective color filter reflects a predetermined wavelength range of an incident visible light, each of the plurality of reflective color filters including three-dimensional photonic crystals of inverse opal structure having colloids of varying sizes; and a plurality of optical switches disposed adjacent to and facing a corresponding one of the plurality of reflective color filters, each of the plurality of optical switches extracts a predetermined color by adjusting an intensity or on/off-frequency of light reflected from the corresponding one of the plurality of reflective color filters.

US Patent 7145170 - Superconducting Quantum Bit NOT gate

Quantum computing is proposed as a possible mechanism having inherent parallel processing advantages over conventional computers. Gradually circuit designs are being proposed to mirror conventional logic functions using quantum computers. The circuit proposed by this patent from NEC performs a controlled NOT function. Claim 1 reads:

1. A superconducting charge quantum multi-bit device, comprising: a first superconducting charge quantum bit device serving as a target quantum bit circuit; a second superconducting charge quantum bit device serving as a control quantum bit circuit; and an electric capacitor coupling the first and second superconducting charge quantum bit devices.

Thursday, December 07, 2006

US Patent 7144683 - Photopatternable Functional Groups for Molecular Electronics

Although there are not yet products on the market based on molecular electronics, Hewlett Packard has laid claim to a dominant position based on their R&D and numerous patents on the use of rotaxane and other molecular structures to create crossbar memories and other high density electronic structures. The fabrication of these devices is typically not compatable with conventional optical lithography approaches which usually require resists that may adversely affect the functional molecules being used. This patent proposes a solution involving photopatternable functional groups to replace the conventional resists. Claim 1 reads:

1. A method for fabricating a multiple electrode device comprising at least one pair of electrodes that form at least one junction and at least one connector species connecting said pair of electrodes in said junction, said junction having a functional dimension in nanometers or micrometers, wherein said at least one connector species comprises said bistable molecule provided with at least one photosensitive functional group for patterning said connector species, said method comprising: (a) forming a first set of said electrodes on a substrate; (b) depositing a film of said bistable molecule(s) including said at least one photosensitive group; (c) exposing portions of said bistable molecular film to desired radiation to thereby cause at least one of photochemical decomposition or photochemical transformation of said at least one photosensitive functional group; and (d) removing unwanted portions of said bistable molecular film to provide a photopatterned film.

US Patent 7144654 - Microscopic Batteries for MEMS

This patent from Bipolar Technologies has priority going back all the way to 1998 (due mostly to USPTO delays) and claims the basic configuration of microscale batteries integrated with microelectromechanical systems. While advantagous to conventional MEMS devices such as accelerometers and optical switches, developments in microrobotics may also require such integration. Claim 1 reads:

1. In combination, at least one microfabricated microelectronic circuit the area of which is no greater than the area of a microelectromechanical system and a microfabricated microscopic battery the area of which is less than the area of the microfabricated microelectronic circuit integrated with the microfabricated microelectronic circuit as an internal low power loss source of electrical energy.

Tuesday, December 05, 2006

US Patent 7144287 - Individually Addressable Vertical Nanofibers

Electron emission based devices such as field emission flat panel displays and e-beam lithography tools are a significant application for vertical carbon nanofibers arrays. Usually such devices actuate a plurality of nanofibers extending from a singular common electrode. This patent from Oak Ridge National Labs teaches formation of individual addressing electrodes for each of the nanofibers for higher resolution digital control on nanofiber arrays. Claim 1 reads:

1. A method, comprising: forming a first individually electrically addressable electrically conductive interconnect directly on at least a part of an insulating surface on a substrate; growing a first vertically aligned carbon nanofiber that is coupled to the first individually electrically addressable electrically conductive interconnect; forming a second individually electrically addressable electrically conductive interconnect directly connected to the insulating surface: growing a second vertically aligned carbon nanofiber that is coupled to the second individually electrically addressable elecrtically conductive interconnect: wherein the first vertically aligned carbon nanofiber is individually electrically addressable via the first individually electrically addressable electrically conductive interconnect and the second vertically aligned carbon nanofiber is individually electrically addressable via the second individually electrically addressable electrically conductive interconnect.

US Patent 7143785 - Microfluid-tronics

The analogy between fluid flow and electrical current flow has been recognized for over a century and many of the mathematical equations describing electron transport appear in analogous forms when describing fluid transport. This patent from CalTech exploits this similarity and proposes an integrated circuit approach to microfluidics to construct devices performing comparator functions and memory functions common to electronics devices but with biological fluids rather than electrons as the transport media. Claim 1 reads:

1. A microfluidic device comprising: a microfluidic flow channel formed in a first layer; a first microfluidic control channel formed in a second layer adjacent to the first layer, the first microfluidic control channel separated from the microfluidic flow channel by a first deflectable membrane integral with the first layer or the second layer; and a second microfluidic control channel adjacent to the first microfluidic control channel and separated from the first microfluidic control channel by a second deflectable membrane.

Monday, December 04, 2006

US Patent 7142075 - MEMS Power Generator

Batteries for implantable medical devices eventually need to be replaced at high expense and inconvenience. This patent from Sandia proposes a way to avoid batteries in implantable medical devices by using a mechanism to transform internally generated mechanical energy to electrical energy via a magnetic micromechanical device. Claim 1 reads:

1. A microelectromechanical (MEM) apparatus, comprising: (a) a meandering electrical pickup disposed on a substrate; and (b) a plurality of permanent magnets spaced apart side-by-side and suspended above the substrate by a soft-magnetic shuttle, with the plurality of permanent magnets generating an electrical voltage across the meandering electrical pickup in response to a movement of the plurality of permanent magnets in a direction substantially parallel to a surface of the substrate.