Wednesday, May 31, 2006

US Patent 7052618 - Nanoparticle Patterning

There are many approaches to fabrication of nanoparticles including chemical synthesis, laser vaporization, and chemical vapor deposition. However, usually only random or highly ordered arrays of nanoparticles may be formed on a substrate and there are few techniques to form arbitrary patterned arrangements. This patent offers one possible solution which may be suitable for mass production because it utilizes the traditional photolithography processes. A polymer film is deposited on a substrate contains nanoparticles maintained in a nonvolatile state by a surrounding "vector polymer". The typical patterning procedures such as commonly employed in UV lithography may then be employed followed by removal of residual organic components leaving an array of nanoparticles in a shape or arrangement determined by the lithography. Claim 1 reads:

1. A nanostructure fabrication method, comprising: forming on a substrate a film including a vector polymer comprising a payload moiety; patterning the film; and removing organic components of the patterned film to form a payload-comprising nanoparticle.

US Patent 7052588 - Nanotube Sensor Using Biotin

Nanotubes have developed some interest in the biosensing area. This particular patent uses biotin (a B vitamin with high affinity bonding for some proteins) in the sensing. The singularly presented claim reads:

1. A bio-molecule sensor comprising: a substrate; a nanotube having first and second ends disposed on the substrate; and a pair of electrodes disposed on the substrate, each electrode contacting an end of the nanotube, one electrode comprising a surface layer including a molecule with an affinity for the bio-molecule, wherein the surface layer includes biotin.

I am somewhat skeptical of this claim but the earliest reference I could find using biotin in nanotube sensors has a priority of January 10, 2003 (by different inventors, see link) while the patent has priority to November 27, 2002.

Tuesday, May 30, 2006

US Patent 7051945 - Nanowire Phase Shifter

Nanosys, the owner of this patent, is one of a handful of promising new companies focusing on nanoelectronics. This company seems to realize that it would be a bad strategy to try to use nanoelectronics to displace bulk silicon electronics on the basis of size alone. Instead, Nanosys is focusing on the use of nanomaterials to do what silicon wafers can't do - bend. Flexible displays, RFID labels, and other upcoming applications require semiconductor materials capable of being formed on flexible and relatively large substrates. However, bulk silicon wafers are rigid and fragile and thus not ideally suitable for such applications. Nanosys proposes using nanowire films to fill the requirements of these new applications. This particular patent focuses on a variable phase shifter (a component of RFID) made using such nanowire films. Claim 1 reads:

1. An adjustable phase shifter formed on a substrate, comprising: a conductor line on the substrate that includes a first conductive segment and a second conductive segment; a thin film of nanowires formed on the substrate in electrical contact with said first conductive segment and said second conductive segment; and a plurality of gate contacts in electrical contact with said thin film of nanowires and positioned between said first conductive segment and said second conductive segment; wherein a phase of an electrical signal transmitted through said conductor line is adjusted by changing a voltage applied to at least one gate contact of the plurality of gate contacts.

Note to patent attorneys- one of the original claims presented for this patent included the phrase "standard semiconductor fabrication processes." The Examiner applied 35 USC 112 2nd paragraph against this claim on the grounds that "standard semiconductor fabrication processes" change too rapidly for this term to have definiteness.

Monday, May 29, 2006

US Patent 7049823 - Electron Emitting Nanotubes Used In Pressure Gauge

In an earlier post I mentioned how reissue patent RE 38561, which contains the basic claims to electron emitting nanotubes, may be the most valuable nanotech patent issued because of the large number of emerging commercial applications of this use of electron emitting nanotubes in flat panel displays, electron microscopy, lithography, microwave amplifiers, etc.
US 7049823 provides an example of yet another new field of application for electron emitting nanotubes - a vacuum gauge. Claim 1 reads -

1. An ionisation vacuum gauge for measuring the residual pressure of a gaseous material in a container (10) comprising: an electron-emitting cathode (31), said cathode is formed by a plurality of nanotubes, distributed over a surface of said cathode, a grid (13; 33; 133; 133') for accelerating the electrons emitted by said cathode, a plate (15; 35) for collecting the ionised positive molecules of said gaseous material, said plate (35) disposed outside of said accelerating grid (33:133;133') and a galvanometer (21) connected to said plate for measuring the plate current to determine the value of the residual pressure inside the container.

Ionisation vacuum gauges are actually fairly commonly used to enable low pressure lithography and microscopy environments. The use of nanotubes as an electron emitter in these devices provides advantages of lower power consumption, a high degree of directional control of the electron beam, and miniaturization.

Sunday, May 28, 2006

US Patent 7049806 - Micromechanical Beam With Resilient Suspension

There are many current commercial applications in divergent fields that employ micromechanical and microelectromechanical systems such as micromirror based displays, microcantilevers for atomic force microscopy, microejectors for inkjet printheads, microsensors, microrelays, etc. Even though micromechanical systems are used in different fields, common problems are found generic to micromechanical structures themselves. This results in inventors focusing on patents for the generic problems of micromechanical structures regardless of the specific application. Unfortunately, the US patent class system does not have a generic class outline for micromechanical systems (although a few areas have been devoted to the fabrication of such systems). This results in a great difficulty for Patent Examiners attempting to search for broadly claimed micromechanical structures. US 7049806 presents an example of such broadly claimed structures. Claim 1 reads:

1. A microelectromechanical system (MEMS) comprising: a beam supported on flexible transverse arms to move longitudinally along a substrate, wherein at least one of the flexible transverse arms is configured to at least one of tolerate and make use of bowing experienced by the arm.

The beam is taught to include structural elements such as serpentine portions allowing for extention and bending of the beam when moving in the direction of extension of the beam. This is taught to compensate for stresses induced by thermal expansion. Unfortunately the Examiner was unaware of earlier patents such as



that would seem to read on some of the claims of US 7049806.

The US patent office has been reluctant to create a patent class devoted to micromechanical systems. Unfortunately this reluctance may result in many micromechanical patents being issued with claims broader than warrented.

Saturday, May 27, 2006

US Patent 7049625 - Nanowire FET With Defect

Basic memory elements often employ the trapping of electrical charge beneath a thin film insulating barrier of a field effect transistor. The inventors of this patent employ the same concept but use a defect region of a nanowire instead of a thin film insulator to store the charge.

Claim 1 reads:

1. Field effect transistor memory cell having a source region, a drain region, a channel region and a gate region, with the channel region extending from the source region to the drain region and being formed by at least one nanowire which has at least one defect such that charges can be trapped in and released from the defects by a voltage applied to the gate region.

Recently the USPTO published a classification outline for nanotechnology patents and one of the subclasses in this class is specifically devoted to FETs with nanowire gates (search ccl/977/938 at Currently there are 23 US patents listed in this field.

Friday, May 26, 2006

US Patent 7048999 - Self-Assembled Objects Made From Single Walled Nanotubes

Self-assembly is a nanofabricatrion approach that is fundamentally different from convention approaches to small scale fabrication used in the manufacture of microelectronics and micromechanical devices. Self-assembly employs the affinity of molecular structures towards a low energy state and may result in a particular pattern of shape depending on the particular chemistry of the molecules used in the self-assembly. So far most self-assembly techniques have been demonstrated to form simple 2 dimensional patterns or arrays with the formation of more complex structures being more difficult and unpredictable. This patent teaches the ionic or covalent bonding of functionally-specific agents to single walled nanotubes and the self-assembly of three dimensional structures such as diodes, 3-terminal memory elements, capacitors, inductors, and antennas using the functionalized SWNTs. Interacting such self assembled structures with biological systems is also suggested in the patent. Claim 1 reads:

1. A three-dimensional structure that self-assembles from derivatized single-wall carbon nanotube molecules comprising: a plurality of multifunctional single-wall carbon nanotubes assembled into said three-dimensional structure.

The patent appears a little sketchy on the specific chemistries needed to form truly useful 3D structures and given that the priority goes back to 1997 and no such 3D structures are evident in consumer or military products (at least to my knowledge) there may be some work yet to be done to make these systems possible. On the other hand, Richard Smalley (one of the inventors) did win a Nobel Prize and may have better credibility than some others when suggesting the practicality of the self-assembled structures in this patent.

US Patent 7048903 - Single Walled Nanotubes with Thin Film Coatings

Richard Smalley was one of the earliest players in the area of fullerene and nanotube research in the early 1990's. Smalley and his group at Rice University filed many patent applications in the '90s dealing with different fabrication methods and uses of nanotubes. However, because of long pendancy times and use of continuations it is only now that these fundamental nanotube patents are being issued. This particular patent has priority to Aug.8, 1996 and includes several broad claims such as:

1. A dispersion of single-walled carbon nanotubes in a liquid comprising an aqueous detergent solution.

2. A dispersion of single-wall carbon nanotubes in a liquid comprising a solvent selected from the group consisting of benzene, toluene, xylene, naphthalene, and combinations thereof.

3. A single-wall carbon nanotube coated with a coating material, wherein the coating material has a nanometer-scale thickness.

11. A rope or bundle of single-wall carbon nanotubes wherein the rope or bundle is coated with a coating material of nanometer-scale thickness.

While these claims are very broad it is noted that they are limited to single walled nanotubes. Several commercial applications of nanotubes are now well underway in non-volatile memory, field emission displays, and polymer composites. However, many of the current applications employ the more easily manufactured multiwalled variety of nanotubes.

Thursday, May 25, 2006

US Patent 7048901 - Electrical Connection to DNA Using Nanotube

There is some interest in the use of biopolymers such as DNA, RNA, and proteins as electrical circuit elements. However, there is difficulty in forming electrical connections between metallic electrodes and biopolymers due to oxide formation on metal electrodes. This patent addresses this problem by using nanotubes instead of metallic electrodes as the connection element.

Claim 1 reads:

1. A production method of an electrical connection structure, the method comprising the steps of: operating at least one carbon nanotube as an electrode to an arbitrary portion of a biopolymer; and contacting the electrode with the biopolymer at the arbitrary portion; wherein the electrode and the biopolymer are fixed together in a stable electrically connected state by the contacting step.

Originally the applicant presented corresponding claims to the biopolymer/nanotube electrical connection structure in addition to the production method. The Examiner applied prior art in which a biopolymer was attached to a nanotube via an intermediate gold layer. Unfortunately for the applicant, the description of "nanotube" in the specification was specifically broad to include modified nanotubes and the attorney was unable to overcome the rejections to the structure claims resulting in these claims cancellation.

Often patent attorneys fear that writing patent specifications that are too narrow may unduly limit the applicant's invention. This case represents an example of how writing specifications that are too broad sometimes have the same effect.

Wednesday, May 24, 2006

US Patent 7048889 - Liquid Transport Using Nanoposts

Microfluidic devices typically employ the transport of picoliter (very small) quantities of biological or chemical fluids using electrostatic forces through channels of micrometer dimensions. These devices may be used as biological or chemical sensors by directing the fluid to a reagent that reacts to a particular biological of chemical fluid and provide an indication of the presence of the particular fluid or may be used in a plurality of other "lab-on-a-chip" applications involving fluid mixing, sorting, etc. However, typical microfluidic devices are limited by the necessity of the micrometer sized channels that limit flexibility if more than one reagent is used or more than a single path for the fluid drops under analysis is desired.

The inventors of this patent solve this problem in a novel way by providing a surface with an array of nanoscale posts above which drops of the target fluid may be directed using electrostatic or capillary force. At certain regions at the bottom of the nanoscale posts reagents are placed. The fluid can move freely over the surface of the nanoposts without reacting with the reagents until a mechanism is actuated (for example a heat source may be used to reduce surface tension of the fluid) and the fluid then flows through the nanoposts contacting the reagent. Claim 1 reads

1. A detector comprising: a surface having a plurality of nanostructured projections disposed thereon, the projections having tips; a reagent pixel on the surface, between the plurality of projections; means for moving a liquid across tips of the nanostructured projections without contacting the reagent pixel; and means for moving the liquid toward said surface in a way such that the liquid contacts said reagent pixel.

Tuesday, May 23, 2006

US Patent 7048771 - Nanoparticle Textile Dye

Using nanoparticles as dyes and inks goes back several years. In fact one of the first patents claiming an application of fullerene nanoparticles was for an ink composition (see US Patent 5114477).

US Patent 7048771 alleges that the use of carbon black nanoparticles in polymeric textiles is new. Specifically it claims

1. A nanoparticle processed textile and polymer system, said nanoparticle processed textile and polymer system comprising: a textile material having an embedded nanoparticle by diffusion, wherein said embedded nanoparticle is distributed in a gradually diluted pattern, having a higher density at or near the surface of said textile and polymer system and gradually decreasing density toward the core; and wherein said nanoparticle is carbon-black.

An interesting earlier patent (not cited in the '771 patent) is US 5900029

This patent also teaches carbon black dye for polymeric textiles and claims

1. A process for coloring a fiber or textile, comprising treating the fiber or textile with a modified carbon black having at least one organic group attached to the carbon black.

It is noted that the '029 patent doesn't refer to carbon black as "nanoparticles" but carbon black typically has diameters on the order of tens of nanometers (see for example "Carbon Nanotubes and Related Structures" by Peter Harris, pgs. 246-250.)

This situation demonstrates how changing terminologies can greatly effect a patent search. A review of the search logic used by the Patent Examiner responsible for US 7048771 reveals that terms such as "nanometer"or "nm" or "nanoparticle" were used to limit the search. This may not be surprising due to the emphasis of "nano" in the claims of the '771 patent, however the cost of such shifts in terminology is a failure to identify important prior art such as the '029 patent.

Monday, May 22, 2006

US Patent 7046539 - Micromechanical FIFO Memory

Commonly used read/write memory devices, such as EEPROM, store information in terms of electrical charges. But this is not the only way. Mechanical memory storage is another, more ancient way, to store retrievable information in the form of the position of gears or levers. However, mechanical memory storage has, until recently, suffered from the inability to store data at high densities. This patent uses the techniques of surface micromachining to create a FIFO (first in-first out) micromechanical memory. Such micromechanical memory devices have some distinct advantages over the electrical memory devices currently used. For one thing electrical interference is removed as a limiting factor and micromechanical memory is immune to threats from EM pulses, which may be a concern in some military applications.

Sunday, May 21, 2006

US Patent 7046439 - Nanoparticle Enhanced Optical Element

The shaping and molding of optical elements to control the divergence and focusing of light is one of the oldest technologies known to man. However, the possibilities of innovation in this field have yet to be exhausted. Control of the size and distribution of nanoparticles within nanoparticle/polymer composites provide a mechanism for controlling the refractive index of the composite and thus how the composite disperses or focuses light. This patent provides for nanoparticles formed on the surface rather than throughout such composites to save cost (by using fewer nanoparticles) while producing identical results. Claim 1 reads:

1. An optical element comprising a substrate with thermoplastic surface features on a surface thereof having an Ra of from 3 to 200 micrometers, the surface features containing a dispersion of minute particles having a particle size dimension less than 100 nanometers.

(Ra: average roughness)

Friday, May 19, 2006

US Patents 7045851 and 7045854 - Nanoparticles in FET gates

There are many approaches on the drawing boards and in laboratories attempting to find new nanoelectronics technology which may extend capabilities beyond the current MOSFET architectures. However, IBM and Hitachi, the respective patent owners, are both taking an intermediate approach for the time being as evidenced by these patents. Rather than trying to create an entirely new nanoelectronics technology, they are enhancing current FET structures with nanostructured material. Both these patents deal with the novel use of nanoparticulate matter in the gates of FET structures.

Quoting the '851 patent- "breaking up a continuous, conducting floating gate 106 into small bits of isolated conducting material can aid in overcoming some of the roadblocks to further scaling. The nanocrystal floating gate 156 has reduced capacitive coupling to the source 151/drain region 152, which leads to a smaller drain turn-on effect. In addition, the nanocrystal floating gate 106 should make the device less susceptible to stress-induced leakage current. That is, if an individual nanocrystal becomes shorted to the channel 154, other nanocrystals remain unaffected. In a standard floating gate device (e.g., such as device 100), any short to the channel 104 is disastrous because charge can no longer be maintained in the floating gate 106. "

Thursday, May 18, 2006

US Patent 7045811-Artificial Atom Network Using Intersecting Nanowires

The technology of this patent is somewhat similar to a system that Hewlett Packard is working on to enable molecular electronics. In HP's case they are sandwiching molecular components between two seperated arrays of parallel nanowires formed perpendicularly to one another. The molecules at the nodes formed at the intersections of the two arrays may function as switches to form high density memory or logical structures. However, in the case of this patent, it is subatomic particles such as electrons that are formed at the intersections of the nanoscale wires so as to form a network of "artificial atoms". Claim 1 reads:

1. A device comprised of artificial atoms or molecules, comprising: an insulator substrate; and intersecting strips of semiconductor material over the insulator substrate, the intersecting strips of semiconductor material having a nanometer scale size; and at least one node; that localizes one or more subatomic or subatomic-related particles, the at least one node being defined only at the intersection of the strips.

"Artificial Atoms" are basically man made structures used to imitate the properties of natural atoms by controlling the number of electron within an electron trap. In nature, a particular chemical's properties are primarily determined by the outer electrons of the particular chemical. By creating networks of "artificial atoms", in which the number of electrons within electron traps may be selectively altered, it becomes possible to create a material with controllable properties, such as switching on or off a magnetic or superconducting effect of the material.

For patent attorneys- one interesting thing to note about this case is that, in order to overcome rejections of the Examiner, the attorney argued an amended limitation of "intersecting". Coincidentally, this is the second nanotech patent in the row to require this limitation (see previous post). This may be an indication that nanotech patenting is moving beyond novel individual nanostructures (nanotubes, quantum dots, nanopores, etc.) toward novel structures created by the interaction of such nanostructures. Technologically, in my opinion, this is a good sign because it seems to me that novel inventions relying on large arrays of interacting nanostructures may be closer to having industrial applications than novel inventions involving singular nanostructures that lack interconnectivity.

Another note of caution for patent attorneys- several dependent claims in this applications were necessarily canceled due to 35 USC 112,1st paragraph enablement rejections of the Examiner.

Wednesday, May 17, 2006

US Patent 7045205 - Intersecting Coated Nanopores

Nanostructured material often refers to material employing nanoparticulate matter, however this is not the only form nanostructured material can take. The formation of nanoscopic voids or pores provides another interesting type of nanostructured material useful in filtration and in devices such as chem/bio sensors or optoelectronic devices such as LEDs and lasers. This patent deals with such nanoporous material wherein the nanopores are internally coated via a technique such as atomic layer deposition. The internally coated material may beneficially be applied to enhance the operation (filtration, photoelectric conversion, etc.) of the nanopores. Claim 1 reads

1. A nanostructured apparatus, comprising: a mesoporous template having a network of regularly-spaced intersecting pores, wherein a characteristic dimension of the pores is between about 1 nm and about 100 nm; and a layer of material that substantially coats one or more walls of the pores to a substantially uniform thickness.

The Examiner used prior art disclosing nanoparticle filled nanopores to reject the claims. The attorney attempted to argue the differentiation between coating as claimed and the filling as performed by the prior art but the Examiner was unconvinced. Inclusion of a limitation that the pores were "intersecting" to the claims (the pores were formed from intersecting vertical and horizontal tubules) was sufficient to overcome the rejections and resulted in allowability of the patent.

Tuesday, May 16, 2006

US Patent 7045108 - Carbon Nanotube Yarn

Carbon nanotubes, entangled within a binding material, are known to be useful for a variety of purposes including forming electromagnetic shielding material or a bulletproof material (see US Patent 6265466 and US Patent 7041372). However, the length of individual nanotubes is usually limited to a few hundred microns which limits the potential of such applications. This patent proposes a method to produce longer nanotubes by end to end bonding of smaller nanotubes.

Claim 1 reads:

1. A method of fabricating a carbon nanotube yarn comprising: (1) forming a carbon nanotube array; and (2) drawing out a bundle of carbon nanotubes from said carbon nanotube array such that a carbon nanotube yarn is formed.

Claim 12 reads:

12. A carbon nanotube yarn comprising a plurality of carbon nanotube bundles which are joined end to end by van der Waals attractive force, wherein each of the carbon nanotube bundles comprises a plurality of carbon nanotubes substantially parallel to each other.

There are a few interesting things about this patent (besides the breadth of the claims). For one thing, the Examiner did not present any rejection during prosecution but rather issued an immediate allowance. This is fairly rare, especially in cases where broad claims are presented for examination. In the Reasons for Allowance the Examiner cited some prior art disclosing nanotube rope formed from entangled nanotubes or nanotubes joined by side to side van der Waals forces in contrast to the claimed "end-to-end" feature of claim 12. Another interesting thing about this patent is that the assignees (patent owners) are based in China. China has not commonly been thought of a large patent player when compared to the US, Europe, and Japan. However, this is one of a series of patents from China that is indicative of China's intention of becoming a serious player in the nanotech patent field.

While not specifically addressed in the patent one other application of this patent, besides EM shielding and bulletproof material, may be something that has come up in science fiction and by some futurists -space elevators.

Monday, May 15, 2006

US Patent 7042003 - Nanoparticle Light Sensor

Many scientists have considered the use of nanostructured materials as comparable to introducing a new state of matter into industrial processes. While most people are used to thinking of matter as being of one of only four forms (solid, liquid, gas, plasma), nanoparticulate matter may add a fifth category - surface. The surface-to-volume ratio for nanoparticles is so high that completely different behavior may be observed when comparing a material in traditional crystalline solid form and crystalline nanoparticle form. US Patent 7042003, assigned to Samsung, demonstrates one example of the exploitation of this difference. Claim 1 reads-

1. A light receiving element comprising: two electrodes positioned opposite each other; and a light receiving portion interposed between the two electrodes, said light receiving portion comprising interconnected nanoparticles each having a core portion and a shell portion, said core portion of each nanoparticle being composed of a higher band gap material and said shell portion of each nanoparticle being composed of a lower band gap material.

Differing band gap materials placed together are used to form pn junctions- a basic component to electronic and optoelectronic devices. It is common for light sensing devices to employ pn junctions, however typically the pn junctions are formed in different layers on a substrate wafer. The inventors of this patent replace the traditional pn junction structure by an interconnected structure generated by cores and shells of nanoparticles. Improved light receiving efficiency, the ability to detect light from multiple directions or of divergent polarity, and the ability to tune the wavelength of light to be detected (determined by the nanoparticle size) are some of the advantages of this type of light sensor.

Saturday, May 13, 2006

US Patent 7041709 - Nanoparticles for Dental Adhesive

The FDA has taken a particular interest in the effects of nanotechnology on their regulatory efforts The reason behind this interest is that some early applications of nanotechnology involve drug delivery mechanisms, cosmetics, and other applications relevant to the FDA's function.

This patent introduces another area where FDA interest might lie-dental adhesives. Claim 1 reads

1. A composition comprising: nanoparticles, each said nanoparticles comprising a siloxane moiety, said siloxane moiety having at least one acidic moiety and at least one polymerizable moiety.

The composition produces a hydrolysis stable, self-etching, self-priming dental adhesive which adheres strongly to surfaces of dental materials, such as dentin, enamel, metal, ceramics, and polymeric material, without prior etching or priming of the surfaces.

Thursday, May 11, 2006

US Patent 7041620 - Single Wall Nanotube Growth Using Group VI Metal Catalyst

Carbon Nanotubes are probably the most talked about type of nanostructure and are starting to see some near term applications in field emission displays, memory devices, and polymer composites. However, none of these applications would be possible without the research and development of scientists such as Richard Smalley, one of the inventors of this patent and numerous other patents on nanotube manufacturing. This particular patent employs catalytic group VI metals such as chromium and tungsten to produce single walled nanotubes of greater purity and homogeneity. The method is cited to produce compositions of matter comprising at least 80% by weight single walled nanotubes and macroscopic carbon fibers containing on the order of 1,000,000 single walled nanotubes in parallel orientation.

Wednesday, May 10, 2006

US Patent 7041372 - Bulletproof Nanotube Armor

Yet another patent that was pending for awhile. This patent was filed in September 2001 by Lockheed Martin and lays claim to entangled single wall nanotubes used in anti-ballistic material such as the armor of a tank, aircraft, or personel. Claim 1 reads

1. A structure arrangement for the protection of a host against an impacting ballistic element, the structure arrangement comprising: a substrate; the substrate coupled to the host; and a composite; the composite disposed on the substrate; the composite comprising a matrix; and a multiplicity of single walled carbon nanotubes; and the single walled carbon nanotubes arranged with respect to the matrix so as to define a substantially entangled array operable to engage the ballistic element.

The Examiner used a prior art reference dealing with a nanotube composite used for EM shielding (US 6265466). Unfortunately this was a very bad reference to use since the EM shielding of the '466 patent employed nanotube alignment for the shielding which contradicted the claimed feature of "a substantially entangled array" and the attorney successfully argued this point.

On first glance I'm a little skeptical of this patent since the advantageous mechanical properties of SWNT/polymer composites have been well documented since the late 1990's and one would think that it would have been obvious to a person of ordinary skill in armor manufacture given polymers such as Kevlar that were widely used for armor to employ SWNT for strengthening purposes. However, whether or not to provide "a substantially entangled array" may be a matter of experimental verification. In any case, if you want to bulletproof your car with entangled single walled nanotubes you better pay Lockheed Martin.

US Patent 7041362 - Nanocrystal Bar Code

This one has been pending for a while (priority goes back to Nov 9, 1998) and apparently lays claim to nanocrystals (i.e. quantum dots) formed in a spatially arranged pattern for providing security (anti-counterfeiting) or verification code patterns. Claim 1 reads-

1. A method of providing a carrier material with an identifiable code pattern, the method comprising: applying an effective amount of one or more species of fluorescent water-soluble nanocrystals to the carrier material and operably linking the nanocrystals to the carrier material in an identifiable code pattern by linking reactive functionalities of the nanocrystal to the surface of the carrier material in a spatial arrangement, wherein the identifiable code pattern is used to determine the identity or authenticity of the carrier material.

Apparently the key differentiating factor from the prior art was that the code pattern was "in a spatial arrangement" as recited in all of the independent claims. The Examiner applied prior art that discussed the use of multiple quantum dots as tags for biological agents but, as argued by the attorney, the pliant nature of the biological cells would not allow spatially arranged deposits of water soluable quantum dots.

Tuesday, May 09, 2006

US Patent 6645402 - Carbon Electron Emitting Device

On occasion I will have a discussion with someone outside of the patent field about patents. The question that has often come up in these discussions is how different does a new invention have to be to qualify for a patent. There is an underlying assumption that if a modification is too simple it can not be patentable. I, of course, explain about the "obvious to one of ordinary skill in the art" standard, used in the U.S. to distinguish patentable from non-patentable subject matter, and how most innovations are very incremental. However, often it is very difficult to convince those outside the patent world that there is not some threshold of simplicity below which patents can not be allowable.

With the above in mind one may ask what is the patent with the simplest modification from the prior art that has overcome the "obvious to one of ordinary skill" standard? I would submit US Patent 6645402 as a possible candidate for this honor.

Claim 1 reads

1. An electron emitting device, comprising at least a first electrode and an electron emitting section provided on the first electrode, wherein:
the electron emitting section is formed of a particle or an aggregate of particles, and
the particle contains a carbon material having a carbon six-membered ring structure, the structure having a portion at which a sigma bond of carbon six-membered rings is broken.

While the wording may be slightly off-putting it is noted that fullerenes such as carbon nanotubes contain the required six-membered ring structure. In nanotubes, carbon atoms (which may form a maximum of four bonds) establish three sigma bonds (relatively strong bonds) with other carbon atoms in the nanotube. Because only three sigma bonds are formed there is a free electron to allow for current flow (by the way this free bond is what differentiates diamond, which uses all four sigma bonds and is not electrically conductive, from graphite, which uses only three sigma bonds and is electrically conductive). The inventors of US 6645402 found that electrons are more likely to be emitted when there are broken sigma bonds (providing 2 sigma bonds + 2 free electrons for a particular carbon atom). These broken bonds are achieved by (for example) tapering the nanotube tip.

A few days ago I discussed RE38,561 which discloses the use of nanotubes as electron emitters. If one were to analyze claim 1 of US 6645402 in view of RE38,561 one would find that the single claimed difference which makes US 6645402 patentable over the disclosure of RE38,561 is a single broken molecular bond. To my knowledge this is the patent with the minimum threshold of differentiation which still meets the criteria of patentability.

Sunday, May 07, 2006

US Patent 7039619 - Nanotechnology for Neural Networks

A couple of months ago at a Nanotech conference Alex Nugent,the inventor of this patent, gave a presentation explaining his ideas and the uses of nanotechnology in neural nets. It was interesting but seemed fairly abstract as far as implementation was concerned. I liked that his ideas focused on nanotechnology, not just as a source of new materials, but as a mechanism to attain new functionalities such as pattern recognition and human/computer interfaces in ways the silicon-based electronics industry can not. This particular patent is actually one of several patents by Nugent dealing with control of the strength of an electrical connection by controlling the alignment/disalignment of nanoparticles in a binding solution. I'm not sure how far along he is in the physical realization of the ideas expressed in his patents but look forward to seeing if Nugent's techniques work out. For more info see

Saturday, May 06, 2006

US Patent 7036769 - Micromechanical Flying Insect

Often I see micromechanical (MEMS) technologies lumped in together with nanotechology. However, there are some serious differences between the two fields. For one thing, nanotechnology is still in the testing and manufacturing stage of development and lacks a widespread toolset for mass production, whereas MEMS typically relies on many of the same fabrication principles used in IC manufacture and is thus suitable for mass production. Therefore, in the next 10-20 years it may be that MEMS, rather than nanotech. becomes a dominant driver of the economy.

Case in point -US 7036769 (published May 2, 2006)

This patent is an improvement on a drive assembly for a wing of a micromechanical flying insect. For all of the speculation about "nanorobots" in science fiction and by futurists there is really very little enabling technology to support such concepts. Microrobots, on the other hand, enabled by the above patent as well as a proliferation of recent patents on microbatteries, microsensors, microactuators, etc. appear to be well on the way to reality.

Thursday, May 04, 2006


For all of the talk of nanotechnology in the press there are actually relatively few patents related to nanotechnology. If one were to consider any patent claiming any one of

a) a new structure or material including a nanoparticle, nanotube, nanowire, quantum dot, or other nanostructure, or
b) a new method or tool for manufacturing or characterizing a structure as in a), or
c) a new method of use of a structure as in a)

as a "nanotechnology" patent and then compared the number of these "nanotechnology" patents with the total number of patents issued by the US in one year (~180,000) the ratio would be far less than 1%.

This combined with the general consensus that nanotechnology will be a large driver of the future economy leads one to believe that the few companies holding these relatively rare patents may be in a very powerful position. So let me start this blog with an analysis of what could be one of the most valuable patents of these rare and valuable patents - US RE38,561

This patent is fairly interesting, not only because of it's potential value, but because it is one of the few nanotech. patents to undergo a reissue examination. Claim 10 reads-

10. A field emission cathode comprising an electron-emitting part of the cathode formed at least in part as a carbon nano-cylinder.

Basically this claim seems to cover any cylindrical carbon nanostructure (such as a carbon nanotube) capable of electron emission. A text book by M.Meyyappan of NASA Ames Research Center published last year and entitled "Carbon Nanotubes: Science and Applications" has an entire chapter devoted to the applications of electron emitting carbon nanotubes. This chapter cites a paper in Science published Nov.17, 1995 entitled "A Carbon Nanotube Field-Emission Electron Source" as the first discussion of this use of nanotubes in the scientific literature. The priority date of RE38,561 is at least Feb.22,1995 (PCT filing date). Therefore, although extremely broad, this patent claim does not appear defective.

The potential analogy between this patent and industry may not be so different than the analogy between the first laser patent and industry. The case of the laser has shown wide ranging applications (such as digital printing, eye surgery, fiber optic communication, etc.) may emerge from the invention of a single device. Electron emitting nanotubes are similarly drawing interest in a variety of devices such as flat panel displays, electron microscopy, lithography tools, and electronic switching devices.

Wednesday, May 03, 2006

Weekly MEMS / Nanotechnology Patent Reviews

I am a former U.S. Patent Examiner who was involved in the creation of a new U.S. patent class for Nanotechnology and thought it would be an interesting idea to provide a blog devoted to a weekly review of newly issued patents in the fields of micromechanical systems and nanotechnology with a focus on the more novel patents being issued in these fields. Stay tuned...