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"Integrated Carbon Nanotube Field Effect Transistor and Nanochannel for Sequencing" in Patent Application Approval Process

June 24, 2014



By a News Reporter-Staff News Editor at Life Science Weekly -- A patent application by the inventors Afzali-Ardakani, Ali (Ossining, NY); Stolovitzky, Gustavo A. (Riverdale, NY); Wang, Deqiang (Ossining, NY), filed on August 20, 2013, was made available online on June 12, 2014, according to news reporting originating from Washington, D.C., by NewsRx correspondents (see also International Business Machines Corporation).

This patent application is assigned to International Business Machines Corporation.

The following quote was obtained by the news editors from the background information supplied by the inventors: "The present invention relates to nanodevices, and more specifically, to sequencing using an integrated carbon nanotube field effect transistor and nanochannel.

"Nanopore sequencing is a method for determining the order in which nucleotides occur on a strand of deoxyribonucleic acid (DNA). A nanopore (also referred to a pore, nanochannel, hole, etc.) can be a small hole in the order of several nanometers in internal diameter. The theory behind nanopore sequencing is about what occurs when the nanopore is submerged in a conducting fluid and an electric potential (voltage) is applied across the nanopore. Under these conditions, a slight electric current due to conduction of ions through the nanopore can be measured, and the amount of current is very sensitive to the size and shape of the nanopore. If single bases or strands of DNA pass (or part of the DNA molecule passes) through the nanopore, this can create a change in the magnitude of the current through the nanopore. Other electrical or optical sensors can also be positioned around the nanopore so that DNA bases can be differentiated while the DNA passes through the nanopore.

"The DNA can be driven through the nanopore by using various methods, so that the DNA might eventually pass through the nanopore. The scale of the nanopore can have the effect that the DNA may be forced through the hole as a long string, one base at a time, like thread through the eye of a needle. Recently, there has been growing interest in applying nanopores as sensors for rapid analysis of biomolecules such as deoxyribonucleic acid (DNA), ribonucleic acid (RNA), protein, etc. Special emphasis has been given to applications of nanopores for DNA sequencing, as this technology holds the promise to reduce the cost of sequencing below $1000/human genome."

In addition to the background information obtained for this patent application, NewsRx journalists also obtained the inventors' summary information for this patent application: "According to an embodiment, a method for base recognition in an integration of a transistor and a nanochannel is provided. The method includes forcing a target molecule down to a carbon nanotube a single base at a time in the nanochannel. The target molecule is forced to the carbon nanotube by applying a gate voltage to a top electrode of the transistor, by a narrow thickness of the nanochannel, or both by applying the gate voltage to the top electrode of the transistor and by the narrow thickness of the nanochannel. The nanochannel having been patterned over the carbon nanotube exposes an exposed portion of the carbon nanotube at a bottom wall of the carbon nanotube, where the top electrode of the transistor is positioned over the exposed portion of the carbon nanotube through the nanochannel. The exposed portion of the carbon nanotube is smaller than a separating distance between bases on the target molecule, and the exposed portion of the carbon nanotube is configured to only accommodate the single base at a time. The target molecule is stretched by the narrow thickness of the nanochannel and by applying a traverse voltage across a length direction of the nanochannel between a first electrode and a second electrode at opposite ends of the nanochannel in the length direction. The target molecule is frictionally restricted by the narrow thickness of the nanochannel causing the target molecule to stretch as the target molecule restrictedly translocates in the length direction while the traverse voltage is applied. The method includes measuring a transistor current while the single base of the target molecule is forced down to the exposed portion of the carbon nanotube in the nanochannel. The single base affects the transistor current. The method includes determining an identity of the single base according to a change in the transistor current while the single base is forced down to the exposed portion of the carbon nanotube in the nanochannel.

"According to an embodiment, a system for base recognition of a target molecule is provided. The system includes a transistor having a source electrode, a drain electrode, and a top electrode. The source electrode is electrically connected to the drain electrode by a carbon nanotube. A nanochannel is formed perpendicularly to the carbon nanotube and formed with a longitudinal direction extending away from the source electrode and the drain electrode. The nanochannel is formed of an insulating layer except at a single bottom location of the nanochannel. The single bottom location of the nanochannel is an exposed portion of the carbon nanotube, and the nanochannel is only formed of the carbon nanotube at the single bottom location. A size of the exposed portion of the carbon nanotube at the single bottom location is less than a separation distance between bases of the target molecule. The top electrode is positioned above the nanochannel to vertically line up to the exposed portion of the carbon nanotube at the single bottom location. The top electrode forces the target molecule down to the carbon nanotube a single base at a time in the nanochannel, and the target molecule is forced to the carbon nanotube by applying a gate voltage to the top electrode of the transistor and by a narrow thickness of the nanochannel. A transistor current is measured while the single base of the target molecule is forced down to the carbon nanotube in the nanochannel, so that the single base affects the transistor current. An identity of the single base is determined according to a change in the transistor current while the single base is forced down to the exposed portion of the carbon nanotube in the nanochannel.

"Additional features and advantages are realized through the techniques of the present invention. Other embodiments and aspects of the invention are described in detail herein and are considered a part of the claimed invention. For a better understanding of the invention with the advantages and the features, refer to the description and to the drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

"The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The forgoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

"FIGS. 1A through 1E illustrate cross-sectional views of fabricating an integrated carbon nanotube field effect transistor (CNT-FET) and nanochannel device according to an embodiment, in which:

"FIG. 1A is a cross-sectional view of the device with a carbon nanotube;

"FIG. 1B is a cross-sectional view of an electrically insulating layer deposited on the surface of the device;

"FIG. 1C is a cross-sectional view of a nanochannel or nanotrench formed through the insulating layer exposing the carbon nanotube;

"FIG. 1D is a cross-sectional view of another electrically insulating layer deposited on the previous insulating layer to seal the nanochannel; and

"FIG. 1E is a cross-sectional view of the device with electrodes deposited.

"FIG. 2A is a cross-sectional view of an integrated carbon nanotube field effect transistor and nanochannel system according to an embodiment.

"FIG. 2B is a top view the integrated carbon nanotube field effect transistor and nanochannel system according to an embodiment.

"FIG. 3A is an abbreviated version of a cross-sectional view of the carbon nanotube field effect transistor and nanochannel system according to an embodiment.

"FIG. 3B is an abbreviated version of a top view of the carbon nanotube field effect transistor and nanochannel system according to an embodiment.

"FIGS. 4A and 4B together are a flow diagram illustrating a method for base recognition in a transistor and a nanochannel system according to an embodiment.

"FIG. 5 is a block diagram that illustrates an example of a computer (computer test setup) having capabilities, which may be included in and/or combined with embodiments."

URL and more information on this patent application, see: Afzali-Ardakani, Ali; Stolovitzky, Gustavo A.; Wang, Deqiang. Integrated Carbon Nanotube Field Effect Transistor and Nanochannel for Sequencing. Filed August 20, 2013 and posted June 12, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=5142&p=103&f=G&l=50&d=PG01&S1=20140605.PD.&OS=PD/20140605&RS=PD/20140605

Keywords for this news article include: Fullerenes, DNA Research, Carbon Nanotubes, International Business Machines Corporation.

Our reports deliver fact-based news of research and discoveries from around the world. Copyright 2014, NewsRx LLC


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Source: Life Science Weekly


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