Nanotechnology Searching Best Practices

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Introduction

Nanotechnology involves the application of molecular and nanostructured materials to achieve new and useful products or to improve the properties of existing products. In contrast to chemistry or chemical engineering, the materials most often discussed in relation to nanotechnology are usually defined in terms of their nanoscale shapes and structure rather than strictly in terms of their chemical composition. In addition, nanomaterials often provide a special property or provide a special function to the products due to their nanoscale physical size such as a high strength-to-weight ratio providing improved mechanical characteristics, a high surface-to-volume ratio which provide high sensitivity or quantum effects which can enhance photoemission or photodetection.

Obstacles Facing the Searcher

The terminology used to describe particular nanomaterials can cause some confusion during patent searching. For example, claims of one patent reciting "nanowires" may be using this as a synonym for "nanotubes". However, in another patent "nanowires" may be defined to be distinct from "nanotubes" in the specification. In addition, the lexicography of many nanomaterials is often not fixed and different patents or non-patent literature may be describing the same material using completely different terms. This can cause great difficulty in performing reliable text searching.

Common Nanotechnology Keywords

Fullerene: Hollow carbon molecules often including a hexagonal lattice structure for the carbon. Some examples of nanomaterials falling into this category include buckyballs (C60), carbon nanotubes, and carbon nanohorns. Fullerene doped with metal atoms are often referred to as fulleride.

Graphene: A single atomic layer of graphite having a hexagonal carbon lattice.

Nanocrystal: A crystalline (usually semiconductor) nanoparticle. This term is usually synonymous with "quantum dot" so patent searchers should use both terms when performing keyword searches.

Nanoparticle: A particle confined to nanometer dimensions in three spatial dimensions. It is notable that nanowires and nanotubes MAY also fall into the category of nanoparticles depending on the applicant's description. Patent searchers should keep in mind that nanocrystals and quantum dots are also forms of nanoparticles and should be considered when formulating a keyword search inquiry.

Nanotube: A hollow cylindrical structure having a nanometer scale diameter. Carbon nanotubes are most common, however searchers should be aware that other forms of nanotubes based on other materials such as silicon, polymer, and boron nitride do exist. Nanotubes can take the form of multiwall structures formed of multiple concentric cylinders or single wall structures formed of a single cylinder. The multiwall nanotubes have electrically conductive properties while the single walled nanotubes may be conductive or semiconductive based on the chirality of the atomic lattice forming the nanotube with respect to the axial direction of the nanotube. Single walled nanotubes are often distinguished by thier chirality in terms of "armchair" nanotubes and "zigzag" nanotubes. The armchair nanotubes are notable as being electrically conductive while the zigzag nanotubes may be either conductive or semiconductive depending on the nanotube diameter.

Nanowire: An extended structure having a nanometer scale diameter. Nanotubes MAY be considered as a type of nanowire but some patents specify a solid cylindrical structure for nanowires to distinguish nanowires from nanotubes. Some common synonyms or special cases of nanowires include nanorods, nanowhiskers, nanofibers, or quantum wires.

Quantum Dot: A nanoparticle exhibiting quantum confinement in three spatial dimensions. It is notable that quantum dots are usually synonymous with semiconductor nanocrystals in the patent literature and both terms should be used when searching.

Quantum Well: A thin film structure exhibiting quantum confinement in one spatial dimensions and which is usually based on a semiconductor material.

Quantum Wire: An extended structure exhibiting quantum confinement in two spatial dimensions and which is usually based on a semiconductor material.

Searching Patent Documents

Patent searching in the art of nanotechnology is normally done with a combination of keyword text searching, patent classification searching, and citation analysis. Search tools that can perform these types of searches well are often preferred by searchers in this field. The USPTO has established class 977 as a cross-reference art collection for nanotechnology searching. The EPO has established class Y01N as a cross-reference art collection for nanotechnology searching. The IPC has established class B82B a cross-reference art collection for nanotechnology searching. Although the different patent offices have established special classes for nanotechnology these classes are still new and many relevant documents fall outside of the class designations. Citation based searching can often help uncover these patents and searchers are advised to perform backward and forward citation based on the closest documents uncovered during the text and classification search.

The following blogs are good sources for recent patents and other information related to nanotechnology:

TinyTechIP
nanoREV
nanotechweb.org

Key Nanotechnology Patents

U.S. Patent 4,343,993 (priority 9/20/1979) : Basic patent for scanning tunneling microscope.

U.S. Patent 4,724,318 (priority 11/26/1985): Basic patent for atomic force microscope.

U.S. Patent 5,260,957 (priority 11/9/1993): Basic patent to quantum dot laser.

U.S. Patent 5,424,054 (priority 5/21/1993): Basic patent for single walled carbon nanotube.

U.S. Patent 5,475,341 (priority 6/1/1992): Basic patent for integrating molecular and semiconductor electronics.

U.S. Patent 5,747,161 (priority 10/31/1991): Basic patent for multiwall carbon nanotubes.

U.S. Patent 5,773,921/RE 38,561(priority 8/21/1995): Basic patent for carbon nanotube electron emitter.

U.S. Patent 6,740,910 (priority 7/28/2000): Basic patent for vertical nanowire field effect transistor.

U.S. Patent 6,891,744 (priority 3/29/1999): Basic patent to reconfigurable nanowire crossbar electronics.

U.S. Patent 7,132,994 (priority 1/16/1997): Basic patent for carbon nanotube optical antenna.

U.S. Patent 7,321,188 (priority 9/16/2002): Basic patent for carbon nanotube yarn light source.

Searching Non-Patent Literature

Non-patent literature can be critical due to nanotechnologies reliance on basic science. Google Scholar is preferred by many searchers because of its easy-to-use interface and ability to search a large number of journals simultaneously. It is also the easiest source from which to retrieve articles in PDF (Portable Document Format). Additionally, Google Scholar’s “cited by” citation indexing has been cheered as a powerful feature similar to those previously only available in subscription-based tools such as Elsevier's Scopus and Thomson ISI Web of Science.

For the dedicated nanotechnology patent searcher a wise investment would be some key textbooks detailing the variety of applications of nanostructured materials. Some of the best of these textbooks include:

1) Carbon Nanotubes: Science and Applications M.Meyyappan (Ed.) CRC Press 2005

2) Nanomaterials Handbook, Y. Gogotsi (Ed.) CRC Press 2006

3) Nano and Molecular Electronics, S.E. Lyshevski (Ed.) CRC Press 2007

4) Nanoelectronics and Information Technology, R.Waser (Ed.) Wiley-VCH 2003

Specific Search Strategies

These search strategies are examples of specific best practices that can be applied during the course of a search in the area of nanotechnology. These are steps to be taken in addition to accepted search practices that apply to all searches. For a more general progression of search steps, please see the Best Practices for General Searching article.

If unsure which patent search tool to use, start with one that provides both powerful keyword searching and fast image searching such as USPTO EAST, Questel QPAT, Google Patent Search, Thomson Innovation, or Minesoft PatBase.

Look up any element abbreviations so that both the abbreviation and the full word can be searched. For example, in a search that involves silicon, one should also search for its abbreviation, Si. This also goes for chemical compounds, such as Silicon Dioxide, abbreviated SiO2.

If the searcher desires clarification of terms or features, a good resource for quickly gaining knowledge of a physical science related technology is Wikipedia. More specifically, if the search contains laser or other optical technology and clarification is needed, look up the terms in the online Encyclopedia of Laser Physics and Technology.

In many cases the patent literature will likely have fewer teachings than non-patent literature sources. NPL resources such as those available from IEEE, Inspec, Knovel, and Google Scholar can be especially useful when searching newer technologies, due to the relative lack of patent documentation available.

Keyword searching combined with citation-based relevancy ranking such as that in Google Patent Search or FreePatentsOnline (for example) can be valuable to the Physical Science Searcher when the goal of the search is to find a handful of highly relevant prior art, rather than an exhaustive list of every piece of prior art.

Key Classification Areas

USPC
977	Nanotechnology

IPC/ECLA
B82B	Nanotechnology

EPO
Y01N	Nanotechnology

Notes

For further reading, searchers should reference the corresponding best practices articles covering Physical Sciences, and Chemical Engineering. Due to some overlap in the fields, the best practices and sources disclosed in those articles may also be applicable to Nanotechnology searches.