U.S. patent application number 11/107996 was filed with the patent office on 2006-10-19 for planar resonant tunneling sensor and method of fabricating and using the same.
Invention is credited to Phillip W. Barth, Curt Flory, Rick Pittaro, Daniel Roitman, Derek Stein.
Application Number | 20060230818 11/107996 |
Document ID | / |
Family ID | 36607476 |
Filed Date | 2006-10-19 |
United States Patent
Application |
20060230818 |
Kind Code |
A1 |
Barth; Phillip W. ; et
al. |
October 19, 2006 |
PLANAR RESONANT TUNNELING SENSOR AND METHOD OF FABRICATING AND
USING THE SAME
Abstract
Planar resonant tunneling sensor devices and methods for using
the same are provided. The subject devices include first and second
electrodes present on a surface of a planar substrate and separated
from each other by a nanodimensioned gap. The devices also include
a first member for holding a sample, and a second member for moving
the first member and planar resonant tunneling electrode relative
to each other. Also provided are methods of fabricating such a
device and methods of using such a device for improved detection
and characterization of a sample.
Inventors: |
Barth; Phillip W.;
(Loveland, CO) ; Stein; Derek; (Loveland, CO)
; Flory; Curt; (Loveland, CO) ; Pittaro; Rick;
(Loveland, CO) ; Roitman; Daniel; (Loveland,
CO) |
Correspondence
Address: |
AGILENT TECHNOLOGIES INC.;INTELLECTUAL PROPERTY ADMINISTRATION, LEGAL
DEPT,
M/S DU404
P.O. BOX 7599
LOVELAND
CO
80537-0599
US
|
Family ID: |
36607476 |
Appl. No.: |
11/107996 |
Filed: |
April 14, 2005 |
Current U.S.
Class: |
73/105 |
Current CPC
Class: |
G01Q 30/02 20130101;
B82Y 15/00 20130101; G01N 15/1031 20130101; B82Y 35/00
20130101 |
Class at
Publication: |
073/105 |
International
Class: |
H01L 31/072 20060101
H01L031/072 |
Claims
1. A sensor device comprising: a first electrode presenting a
planar surface at a planar surface of a substrate; a second
electrode presenting a planar surface at said planar surface of
said substrate and spaced apart by a gap from said first electrode
wherein said gap has a width ranging in length from about 1 nm to
about 8 nm; a first member capable of holding a sample under test;
and a second member attached to said first member and capable of
moving said sample under test over said gap in relative direction
from said first electrode to said second electrode.
2. (canceled)
3. The device according to claim 1, wherein said first member
comprises atomic force microscopy (AFM) tip.
4. (canceled)
5. The device according to claim 1, wherein said first member is
positioned above said surface at a distance ranging from about 0.1
nm to about 100 nm.
6. The device according to claim 1, wherein said nanodimensioned
gap is occupied by a spacer element comprising an insulating
material.
7. The device according to claim 6, wherein said insulating
material comprises silicon dioxide.
8. The device according to claim 1, wherein said first and second
electrodes comprise platinum.
9. The device according to claim 1, wherein said first and second
electrodes comprise polycrystalline silicon.
10. The device according to claim 1, wherein said planar substrate
comprises single-crystal silicon.
11. A method for fabricating the device according to claim 1, said
method comprising: (a) providing a first insulator layer atop a
planar substrate; (b) depositing a first conductive layer on a
first portion of said first insulator layer; (c) depositing a
spacer element layer over said first conductive layer and a second
portion of said surface of said first insulator layer; (d)
depositing a second conductive layer over a portion of spacer
element layer; and (e) removing a portion of said second conductive
layer and said spacer element layer to produce a structure
comprising first and second electrodes present on a surface of a
planar substrate and separated from each other by a nanodimensioned
gap to produce the device according to claim 1.
12. The method according to claim 11, wherein said removing step
(d) comprises polishing said surface to produce a flat surface.
13. The method according to claim 12, wherein said polishing
comprises using a chemomechanical polishing protocol.
14. The method according to claim 11, wherein said method further
comprises positioning said sensor in a device that further
includes: a first member for holding a sample; and a second member
for moving said first member and planar resonant tunneling sensor
relative to each other.
15. A method comprising; (a) positioning a sample on a first member
of the device according to claim 1; and (b) moving said positioned
sample relative to said first and second electrodes.
16. The method according to claim 15, wherein said method comprises
maintaining a constant first voltage applied to said first and
second electrodes while sample is moved relative to said
electrodes.
17. The method according to claim 16, wherein said method further
comprises reiterating step (b) at least once at a second voltage
that is different from said first voltage.
18. The method according to claim 15, wherein said method is a
method for characterizing a quantum dot.
19. The method according to claim 15, wherein said method is a
method of characterizing a macromolecule.
20. The method according to claim 15, wherein said method of
characterizing is a method of characterizing a nanocrystal.
Description
BACKGROUND OF THE INVENTION
[0001] The quantum mechanical phenomenon of "resonant tunneling"
was first analyzed in 1969 by Esaki and Tsu in 1969 (Esaki et al.,
IBM J. Res. and Develop. 14:61-69 (1970). The concept of "resonant
tunneling" has since evolved into that of the "resonant tunneling
diode" (RTD), wherein a central region containing some central
moiety, for example a quantum dot, is placed between two quantum
mechanical tunneling barriers. Two conducting electrodes in contact
with the two quantum mechanical tunneling barriers can therefore
allow the injection of electrical current from a first electrode,
across a first barrier to the moiety, and from the moiety across a
second barrier to the second electrode.
[0002] If an energy level in the central moiety matches the
electron energy in the first electrode, some enhancement of
electrical current through the RTD occurs. This phenomenon can be
called matched-level resonance.
[0003] If the matched-level resonance condition is present, and if
in addition the two quantum mechanical tunneling barriers are equal
in magnitude, a tremendous additional enhancement in electrical
current through the RTD occurs. This second phenomenon wherein the
two quantum mechanical tunneling barriers are equal in magnitude
can be called matched-barrier resonance.
[0004] A variant of the resonant tunneling diode is used with a
scanning tunneling microscope (STM) in a procedure called "resonant
tunneling spectroscopy," which has been refined into a procedure
called "shell tunneling spectroscopy" (Bakkers, et al., Nano
Letters, 1(10):551-556 (2001)).
[0005] The prior shell-tunneling spectroscopy work has been limited
because the sample under test is fixed in place in a single
position on top of an insulator of constant thickness. In order for
the desirable phenomenon matched-barrier resonance to be employed
in such a device, the magnitude of the upper quantum mechanical
tunneling barrier due to the separation of the STM tip from the
sample under test must be matched to the magnitude of the lower
quantum mechanical tunneling barrier due to the presence of the
insulator between the sample under test and the conducting
substrate, and this is difficult to achieve in practice.
[0006] Thus there exists a need for a tunneling spectrometer in
which the phenomenon of matched-barrier resonance can be
effectively employed, and at the same time the phenomenon of
matched-energy resonance can also be made to occur, in order to
obtain a complete density of states for a test sample. The present
invention addresses this need.
Relevant Literature
[0007] Bakkers et al., Nano Letters, 1(10):551-556 (2002); Chang et
al., Applied Physics Lett., 24(12):593-595 (1974); Goodhue et al.,
Applied Physics Lett., 49(17): 1086-1088 (1986); Sollner et al.,
Applied Physics Lett., 43(6):588-590 (1983); Esaki et al., IBM J.
Res. Dev., 14:61-65 (1970); and Sollner et al., Applied Physics
Lett., 45(12):1319-1321 (1984).
SUMMARY OF THE INVENTION
[0008] Planar resonant tunneling sensors and methods for using the
same are provided. The subject sensors include first and second
electrodes present on a surface of a planar substrate and separated
from each other by a nanodimensioned gap. The devices further
include a first member for holding a sample, and a second member
for moving said first member and planar resonant tunneling
electrode relative to each other. Also provided are methods of
fabricating such a device and methods of using such a device for
improved detection and characterization of a sample.
[0009] One feature of the invention provides a device including a
planar resonant tunneling sensor including first and second
electrodes present on a surface of a planar substrate and separated
from each other by a nanodimensioned gap, a first member for
holding a sample, and a second member for moving said first member
and planar resonant tunneling electrode relative to each other. In
some embodiments, the first and second members comprise an
integrated structure. In further embodiments, the integrated
structure is an atomic force microscopy (AFM) tip. In other
embodiments, the nanodimensioned gap has a width ranging in length
from about 1 to about 8 nm. In some embodiments, the second member
moves the first member sequentially across the first electrode,
nanodimensioned gap and second electrode at a distance ranging from
about 0.1 nm to about 10 nm.
[0010] In some embodiments, the nanodimensioned gap includes an
insulating material. In such embodiments, the insulating material
may be silicon dioxide. In some embodiments, the first and second
electrodes comprise platinum or polycrystalline silicon. In further
embodiments, the planar substrate includes single-crystal
silicon.
[0011] Another feature of the invention provides a method for
fabricating a planar resonant tunneling sensor, the method
including providing a first insulating layer atop a planar
substrate, depositing a first conductive layer on a first portion
of a surface of the first insulating layer, depositing a spacer
layer over the first conductive layer and a second portion of the
surface of the first insulating layer, depositing a second
conductive layer over a portion of the surface of the second
insulating layer, and removing a portion of the deposited second
conductive layer and the insulator layer to produce a planar
resonant tunneling electrode sensor comprising first and second
electrodes present on a surface of a planar substrate and separated
from each other by a nanodimensioned gap. A portion of the spacer
layer in the nanodimensioned gap, and extending from the upper
extent of the nanodimensioned gap downward to the first insulating
layer, may subsequently be removed, for example by chemical
etching. If the spacer layer comprises an insulating material it
may be left in place.
[0012] A further feature of the invention provides a method of
forming a nanodimensioned gap suitable for various purposes, for
example to serve as electrical contacts to nanoscale devices
comprising diodes, transistors, and the like.
[0013] In some embodiments the removal of a portion of the
deposited second conductive layer includes polishing the surface to
produce a flat surface. In further embodiments, the polishing
includes using a chemomechanical polishing protocol. In some
embodiments, the method further includes positioning the sensor in
a device that further includes a first member for holding a sample
and a second member for moving the first member and planar resonant
tunneling sensor relative to each other.
[0014] Yet another feature of the present invention provides a
method including positioning a sample on a first member of a device
including a planar resonant tunneling sensor comprising first and
second electrodes present on a surface of a planar substrate and
separated from each other by a nanodimensioned gap, a first member
for holding a sample, and a second member for moving said first
member and planar resonant tunneling electrode relative to each
other, and moving the positioned sample relative to the planar
resonant tunneling sensor while monitoring the current between the
first and second electrodes.
[0015] In some embodiments, the method includes maintaining a
constant first voltage applied to the sensor while the sample is
moved relative to said sensor. In some embodiments the method
further includes reiterating moving the positioned sample relative
to the planar resonant tunneling sensor while monitoring the
voltage between the first and second electrodes at least once at a
second voltage that is different from the first voltage. In some
embodiments, the method is a method for characterizing a quantum
dot, a macromolecule, or a nanocrystal.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The invention is best understood from the following detailed
description when read in conjunction with the accompanying
drawings. It is emphasized that, according to common practice, the
various features of the drawings are not to scale. On the contrary,
the dimensions of the various features are arbitrarily expanded or
reduced for clarity. Included in the drawings are the following
figures:
[0017] FIG. 1 is a schematic illustration of a cross-section at
plane 1a of FIG. 3 of an embodiment 100 of the present
invention.
[0018] FIGS. 2A and 2B are schematic illustrations of
cross-sections at plane 1a of FIG. 3 of an embodiment 100 of the
present invention with additional elements and a sample 116 present
in the first member for holding a sample 107. The arrow shows the
direction the sample is moved over the nanodimensioned gap
[0019] FIG. 3 is a schematic illustration of a top plan view of an
embodiment 100 of the present invention.
[0020] FIGS. 4A-4F illustrate sequential steps of a method of
fabricating embodiment 100 of the present invention.
[0021] FIG. 5A is schematic illustration of a top plan view of an
embodiment 100 of the present invention during a stage in the
fabrication method corresponding to the stage shown in FIG. 4E.
Cross-section plane 1a indicates the location of cross section
shown in FIG. 4E.
[0022] FIG. 5B is schematic illustration of a top plan view of an
embodiment 100 of the present invention during a stage in the
fabrication method corresponding to the stage shown in FIG. 4F.
Cross-section plane 1a indicates the location of cross section
shown in FIG. 4F.
[0023] FIGS. 6A and 6B are schematic illustrations of
cross-sections at plane 1a of FIG. 3 of an embodiment 100 of the
present invention with the adhesion promoting layers 120.
[0024] FIGS. 7A-7E are schematic illustrations of resonant
tunneling conditions for a resonant tunneling spectrometer with
variable geometry.
DEFINITIONS
[0025] A "biopolymer" is a polymer of one or more types of
repeating units, regardless of the source (e.g., biological (e.g.,.
naturally-occurring, obtained from a cell-based recombinant
expression system, and the like) or synthetic). Biopolymers may be
found in biological systems and particularly include polypeptides,
polynucleotides, proteoglycans, etc., including compounds
containing amino acids, nucleotides, or a mixture thereof.
[0026] The terms "polypeptide" and "protein" are used
interchangeably throughout the application and mean at least two
covalently attached amino acids, which includes proteins,
polypeptides, oligopeptides and peptides. A polypeptide may be made
up of naturally occurring amino acids and peptide bonds, synthetic
peptidomimetic structures, or a mixture thereof. Thus "amino acid",
or "peptide residue", as used herein encompasses both naturally
occurring and synthetic amino acids. For example,
homo-phenylalanine, citrulline and noreleucine are considered amino
acids for the purposes of the invention. "Amino acid" also includes
imino acid residues such as proline and hydroxyproline. The side
chains may be in either the D- or the L-configuration.
[0027] In general, biopolymers, e.g., polypeptides or
polynucleotides, may be of any length, e.g., greater than 2
monomers, greater than 4 monomers, greater than about 10 monomers,
greater than about 20 monomers, greater than about 50 monomers,
greater than about 100 monomers, greater than about 300 monomers,
usually up to about 500, 1000 or 10,000 or more monomers in length.
"Peptides" and "oligonucleotides" are generally greater than 2
monomers, greater than 4 monomers, greater than about 10 monomers,
greater than about 20 monomers, usually up to about 10, 20, 30, 40,
50 or 100 monomers in length. In certain embodiments, peptides and
oligonucleotides at between 5 and 30 amino acids in length.
[0028] The terms "polypeptide" and "protein" are used
interchangeably herein. The term "polypeptide" includes
polypeptides in which the conventional backbone has been replaced
with non-naturally occurring or synthetic backbones, and peptides
in which one or more of the conventional amino acids have been
replaced with one or more non-naturally occurring or synthetic
amino acids. The term "fusion protein" or grammatical equivalents
thereof references a protein composed of a plurality of polypeptide
components, that while typically not attached in their native
state, typically are joined by their respective amino and carboxyl
termini through a peptide linkage to form a single continuous
polypeptide. Fusion proteins may be a combination of two, three or
even four or more different proteins. The term polypeptide includes
fusion proteins, including, but not limited to, fusion proteins
with a heterologous amino acid sequence, fusions with heterologous
and homologous leader sequences, with or without N-terminal
methionine residues; immunologically tagged proteins; fusion
proteins with detectable fusion partners, e.g., fusion proteins
including as a fusion partner a fluorescent protein,
.beta.-galactosidase, luciferase, and the like.
[0029] A "monomeric residue" of a biopolymer is a subunit, i.e.,
monomeric unit, of a biopolymer. Nucleotides are monomeric residues
of polynucleotides and amino acids are monomeric residues of
polypeptides.
[0030] A "substrate" refers to any surface that may or may not be
solid and which is capable of holding, embedding, attaching or
which may comprise the whole or portions of an excitable
molecule.
[0031] The term "nanodimensional" or "nanodimensioned" refers to a
feature ranging in size from about 0.5 nm to around 300 nm in
diameter.
[0032] The term "tunneling" refers to quantum mechanical tunneling,
comprising the movement of a particle from one location to another
through an energy barrier which would, in the absence of quantum
mechanical effects, prevent the movement of the particle through
the energy barrier.
[0033] The term "resonant tunneling" refers to the tunneling of a
particle, typically an electron, from one location to another
through two or more energy barriers enclosing one or more quantum
well states situated between the locations. The one location and
another typically comprise electrodes.
[0034] Resonant tunneling comprises two effects, one called
"matched level resonance" and one called "matched barrier
resonance."
[0035] Matched level resonance may be detected as enhanced
conduction between two electrodes as seen in a plot of the
differential of current with respect to voltage when plotted versus
applied voltage, i.e., a peak in dI/dV versus V, where I is
current, V is applied voltage, and dI/dV is the differential of
current with respect to voltage.
[0036] Matched barrier resonance may be detected, when the
condition of matched level resonance is also present, as greatly
enhanced conduction between two electrodes as seen in a plot of
current with respect to voltage when plotted versus applied
voltage, i.e., a peak in I versus V.
[0037] The term "ramping potential" or "bias potential" refers to
having the ability to establish a variety of different voltages
over time. In certain cases, this may be referred to as a "scanning
voltage," "ramping voltage," or time varying voltage. A ramping
potential may provided by a "ramping potential-providing element"
or a "potential-providing element".
[0038] "Hybridizing", "annealing" and "binding", with respect to
polynucleotides, are used interchangeably. "Binding efficiency"
refers to the productivity of a binding reaction, measured as
either the absolute or relative yield of binding product formed
under a given set of conditions in a given amount of time.
"Hybridization efficiency" is a particular sub-class of binding
efficiency, and refers to binding efficiency in the case where the
binding components are polynucleotides.
[0039] It will also be appreciated that throughout the present
application, that words such as "first", "second" are used in a
relative sense only. A "set" may have one type of member or
multiple different types. "Fluid" is used herein to reference a
liquid.
[0040] The terms "symmetric" and "symmetrized" refer to the
situation in which the tunneling barriers from each electrode to
the biopolymer are substantially equal in magnitude.
[0041] The terms "portion" and "portion of a biopolymer" refer to a
part, subunit, monomeric unit, portion of a monomeric unit, atom,
cluster of atoms, charge or charged unit.
[0042] In many embodiments, the methods are coded onto a
computer-readable medium in the form of "programming", where the
term "computer readable medium" as used herein refers to any
storage or transmission medium that participates in providing
instructions and/or data to a computer for execution and/or
processing. Examples of storage media include floppy disks,
magnetic tape, CD-ROM, a hard disk drive, a ROM or integrated
circuit, a magneto-optical disk, or a computer readable card such
as a PCMCIA card and the like, whether or not such devices are
internal or external to the computer. A file containing information
may be "stored" on computer readable medium, where "storing" means
recording information such that it is accessible and retrievable at
a later date by a computer.
[0043] With respect to computer readable media, "permanent memory"
refers to memory that is permanent. Permanent memory is not erased
by termination of the electrical supply to a computer or processor.
Computer hard-drive ROM (i.e. ROM not used as virtual memory),
CD-ROM, floppy disk and DVD are all examples of permanent memory.
Random Access Memory (RAM) is an example of non-permanent memory. A
file in permanent memory may be editable and re-writable.
[0044] A "computer-based system" refers to the hardware means,
software means, and data storage means used to analyze the
information of the present invention. The minimum hardware of the
computer-based systems of the present invention comprises a central
processing unit (CPU), input means, output means, and data storage
means. A skilled artisan can readily appreciate that any one of the
currently available computer-based system are suitable for use in
the present invention. The data storage means may comprise any
manufacture comprising a recording of the present information as
described above, or a memory access means that can access such a
manufacture.
[0045] To "record" data, programming or other information on a
computer readable medium refers to a process for storing
information, using any such methods as known in the art. Any
convenient data storage structure may be chosen, based on the means
used to access the stored information. A variety of data processor
programs and formats can be used for storage, e.g. word processing
text file, database format, etc.
[0046] A "processor" references any hardware and/or software
combination that will perform the functions required of it. For
example, any processor herein may be a programmable digital
microprocessor such as available in the form of an electronic
controller, mainframe, server or personal computer (desktop or
portable). Where the processor is programmable, suitable
programming can be communicated from a remote location to the
processor, or previously saved in a computer program product (such
as a portable or fixed computer readable storage medium, whether
magnetic, optical or solid state device based). For example, a
magnetic medium or optical disk may carry the programming, and can
be read by a suitable reader communicating with each processor at
its corresponding station.
[0047] "Communicating" information means transmitting the data
representing that information as electrical signals over a suitable
communication channel (for example, a private or public network).
"Forwarding" an item refers to any means of getting that item from
one location to the next, whether by physically transporting that
item or otherwise (where that is possible) and includes, at least
in the case of data, physically transporting a medium carrying the
data or communicating the data. The data may be transmitted to the
remote location for further evaluation and/or use. Any convenient
telecommunications means may be employed for transmitting the data,
e.g., facsimile, modem, internet, etc.
[0048] The term "adjacent" refers to anything that is near, next to
or adjoining. For instance, a nanopore referred to as "adjacent to
an excitable molecule" may be near an excitable molecule, it may be
next to the excitable molecule, it may pass through an excitable
molecule or it may be adjoining the excitable molecule. "Adjacent"
can refer to spacing in linear, two-dimensional and
three-dimensional space. In general, if a quenchable excitable
molecule is adjacent to a nanopore, it is sufficiently close to the
edge of the opening of the nanopore to be quenched by a biopolymer
passing through the nanopore. Similarly, electrodes that are
positions adjacent to a nanopore are positioned such that resonance
tunneling occurs a biopolymer passes through the nanopore.
Compositions that are adjacent may or may not be in direct
contact.
[0049] If one composition is "bound" to another composition, the
bond between the compositions does not have to be in direct contact
with each other. In other words, bonding may be direct or indirect,
and, as such, if two compositions (e.g., a substrate and a
nanostructure layer) are bound to each other, there may be at least
one other composition (e.g., another layer) between to those
compositions. Binding between any two compositions described herein
may be covalent or non-covalent.
[0050] The term "assessing" includes any form of measurement, and
includes determining if an element is present or not. The terms
"determining", "measuring", "evaluating", "assessing" and
"assaying" are used interchangeably and may include quantitative
and/or qualitative determinations. Assessing may be relative or
absolute. "Assessing the presence of" includes determining the
amount of something present, and/or determining whether it is
present or absent.
[0051] Unless defined otherwise, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which this invention belongs. Although
any methods and materials similar or equivalent to those described
herein can be used in the practice or testing of the present
invention, the preferred methods and materials are now described.
All publications mentioned herein are incorporated herein by
reference to disclose and describe the methods and/or materials in
connection with which the publications are cited.
DETAILED DESCRIPTION OF THE INVENTION
[0052] Planar resonant tunneling sensors and methods for using the
same are provided. The subject sensors include first and second
electrodes present on a surface of a planar substrate and separated
from each other by a nanodimensioned gap, a first member for
holding a sample, and a second member for moving said first member
and planar substrate relative to each other. Also provided are
methods of fabricating such a device and method of using such a
device for improved detection and characterization of a nanoscale
moiety such a biopolymer.
[0053] Before the present invention described, it is to be
understood that this invention is not limited to particular
embodiments described, as such may, of course, vary. It is also to
be understood that the terminology used herein is for the purpose
of describing particular embodiments only, and is not intended to
be limiting, since the scope of the present invention will be
limited only by the appended claims.
[0054] Where a range of values is provided, it is understood that
each intervening value, to the tenth of the unit of the lower limit
unless the context clearly dictates otherwise, between the upper
and lower limits of that range is also specifically disclosed. Each
smaller range between any stated value or intervening value in a
stated range and any other stated or intervening value in that
stated range is encompassed within the invention. The upper and
lower limits of these smaller ranges may independently be included
or excluded in the range, and each range where either, neither or
both limits are included in the smaller ranges is also encompassed
within the invention, subject to any specifically excluded limit in
the stated range. Where the stated range includes one or both of
the limits, ranges excluding either or both of those included
limits are also included in the invention.
[0055] Unless defined otherwise, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which this invention belongs. Although
any methods and materials similar or equivalent to those described
herein can be used in the practice or testing of the present
invention, the preferred methods and materials are now described.
All publications mentioned herein are incorporated herein by
reference to disclose and describe the methods and/or materials in
connection with which the publications are cited.
[0056] It must be noted that as used herein and in the appended
claims, the singular forms "a", "an", and "the" include plural
referents unless the context clearly dictates otherwise. Thus, for
example, reference to "a biopolymer" includes a plurality of such
biopolymers and reference to "the electrode" includes reference to
one or more electrodes and equivalents thereof known to those
skilled in the art, and so forth. It is further noted that the
claims may be drafted to exclude any optional element. As such,
this statement is intended to serve as antecedent basis for use of
such exclusive terminology as "solely," "only" and the like in
connection with the recitation of claim elements, or use of a
"negative" limitation.
[0057] The publications discussed herein are provided solely for
their disclosure prior to the filing date of the present
application. Nothing herein is to be construed as an admission that
the present invention is not entitled to antedate such publication
by virtue of prior invention. Further, the dates of publication
provided may be different from the actual publication dates which
may need to be independently confirmed.
[0058] As will be apparent to those of skill in the art upon
reading this disclosure each of the individual embodiments
described and illustrated herein has discrete components and
features which may be readily separated from or combined with the
features of any of the other several embodiments without departing
from the scope or spirit of the present invention.
The Subject Devices
[0059] The present invention provides devices including a planar
resonant tunneling sensor. FIGS. 1 and 2A-2B illustrate
cross-sections and FIG. 3 illustrated a top plan view of an
embodiment 100 of the present invention, and are used in the
flowing description. In general, the device of the present
invention includes a planar resonant tunneling sensor present on
the surface of a planar substrate 101 and a first member 107 for
holding a sample and a second member 108 for moving the first
member 107 and the planar resonant tunneling sensor relative to
each other. The planar resonant tunneling sensor includes a first
103 and second 105 electrode elements separated by a
nanodimensioned gap 106.
[0060] The planar substrate 101 may comprise of a variety of
materials known in the art for designing substrates and nanopores.
A substrate suitable for use with the subject device may include
one or more layers of one or more materials including, but not
limited to, single-crystal silicon, silicon nitride, silicon
dioxide, platinum or other metals, silicon oxynitride, silicon rich
nitride, organic polymers, and other insulating layers, carbon
based materials, plastics, metals, or other materials known in the
art for etching or fabricating semiconductor or electrically
conducting materials. A suitable substrate need not be of uniform
thickness. The substrate may or may not be a solid material, and
for example may comprise in part or in whole a mesh, wire, or other
material on which a planar resonant tunneling sensor may be
constructed. The substrate may comprise various shapes and sizes.
However, it must be large enough and of sufficient width to be
capable of supporting a planar resonant tunneling sensor. In
representative embodiments, the substrate has a width ranging from
about 1 mm to about 10 mm, such as from about 3 mm to about 5 mm .
In representative embodiments, the substrate has a thickness
ranging from about 50 .mu.m to about 2.5 mm, such as from about 200
.mu.m to about 600 .mu.m. In addition, the substrate may comprise
of various structural properties, such as rigid or flexible.
However, the substrate must be sufficiently rigid enough to support
the elements of the planar resonant tunneling sensor.
[0061] In addition, the device 100 of the present invention
includes a planar resonant tunneling sensor. The term "resonant
tunneling" refers to the tunneling of a particle, typically an
electron, from one location to another through two or more energy
barriers enclosing one or more quantum well states situated between
the locations. The one location and another typically comprise
electrodes.
[0062] Resonant tunneling comprises two effects, one called
"matched level resonance" and one called "matched barrier
resonance."
[0063] Matched level resonance may be detected as enhanced
conduction between two electrodes as seen in a plot of the
differential of current with respect to voltage when plotted versus
applied voltage, i.e., a peak in dI/dV versus V, where I is
current, V is applied voltage, and dI/dV is the differential of
current with respect to voltage.
[0064] Matched barrier resonance may be detected, when the
condition of matched level resonance is also present, as greatly
enhanced conduction between two electrodes as seen in a plot of
current with respect to voltage when plotted versus applied
voltage, i.e., a peak in I versus V.
[0065] A suitable planar resonant tunneling sensor for use with
subject invention includes a first 103 and second 105 electrodes
separated by a nanodimensioned gap 106. In some embodiments, the
nanodimensioned gap 106 includes a spacer element 104. In some
embodiments the spacer element 104 may comprise an insulator.
[0066] In some embodiments, the first 103 and second 105 electrodes
will have a thickness ranging from about 0.1 .mu.m to about 5
.mu.m, including from about 0.5 .mu.m to about 1 .mu.m. In certain
embodiments, the spacer element 104 will have a thickness ranging
from about 0.5 nm to about 10 nm, including from about 1 nm to
about 9 nm, from about 2 nm to about 7 nm, from about 3 nm to about
6 nm, including about 4 nm to about 5 nm. In certain embodiments,
the nanodimensioned gap 106 will have a width ranging from about
ranging from about 0.5 nm to about 10 nm, including from about 1 nm
to about 9 nm, from about 2 nm to about 7 nm, from about 3 nm to
about 6 nm, including about 4 nm to about 5 nm.
[0067] The first 103 and second 105 electrodes may be made up of a
variety of electrically conductive materials. Such materials
include, but are not limited to, metals, silicides, polycrystalline
silicon, organic conductors and superconductors, electrically
conductive metals and alloys of tin, copper, zinc, iron, magnesium,
cobalt, nickel, platinum, and vanadium. Other materials well known
in the art that provide for electrical conduction may also be
employed. The spacer element 104 may be made up of a variety of
materials that provide for insulation between the first 103 and
second 105 electrodes. A variety of suitable materials are well
known in the art and may be used with the subject device.
Representative materials include, for example, silicon dioxide,
silicon nitride, silicon oxynitride, silicon rich nitride, organic
polymers, and plastics, etc. The spacer element 104 may also be
made up of a variety of electrically conductive materials. Such
materials include, but are not limited to, metals, suicides,
polycrystalline silicon, organic conductors and superconductors,
electrically conductive metals and alloys of tin, copper, zinc,
iron, magnesium, cobalt, nickel, platinum, and vanadium. The spacer
element 104 may be removed, for example by means comprising
chemical etching, in the region of nanodimensioned gap 106 and
extending downward to first insulating layer 102.
[0068] Referring to FIGS. 1 and 2A, the subject device 100 further
includes a first member 107 for holding a sample above the planar
resonant tunneling sensor and a second member 108 for moving the
first member 107 and the planar resonant tunneling sensor relative
to each other. The first member 107 can be made of a variety of
materials that are capable of holding a sample in position above
the planar resonant tunneling sensor. In some embodiments the first
member 107 is non-conductive and is an atomic force microscope
(AFM) tip. In other embodiments the first member 107 is conductive
and is a scanning tunneling microscope (STM) tip. In representative
embodiments, the first element 107 holds the sample above first
electrode 103, nanodimensioned gap 106 and second electrode 105 at
a distance from about 0.1 nm to about 100 nm, including from about
0.5 nm to about 10 nm, such as from about 1 nm to about 2 nm. The
second member 108 can be made of a variety of materials to provide
an element that is capable of moving the first member 107 and the
planar resonant tunneling sensor relative to each other. In some
embodiments, the first member 107 and the second member 108 are
separate units that do not comprise a single integrated structure.
In certain embodiments, the first member 107 and second member 108
are a single integrated structure. In some embodiments the first
member 107 and the second member 108 are an integrated structure in
which the first member 107 is an AFM tip and the second member is
the movement mechanisms of an AFM device associated with the tip,
as found in AFM devices. In other embodiments the first member 107
and the second member 108 are an integrated structure in which the
first member 107 is an STM tip and the second member is the
movement mechanisms of an STM device associated with the tip, as
found in STM devices. In further embodiments, the first member 107
may further include an optional insulating material 117.
[0069] Referring to FIG. 3, the subject device 100, in some
embodiments, will further include an element 114 for applying an
electrical voltage between the first 103 and second 105 electrodes.
The electrical voltage generating element 114 may be positioned
anywhere relative to the substrate 101, the nanodimensional gap
106, the first electrode 103 and the second electrode 105. The
electrical voltage generating element 114 should be capable of
ramping to establish a time-varying voltage between the first
electrode 103 and the second electrode 105. A variety of electrical
voltage generating elements 114 may be employed with the present
invention. A number of these electrical voltage generating elements
114 are known in the art. The electrical voltage generating element
114 has the ability to ramp to establish the time-varying voltage
between the first electrode 103 and the second electrode 105.
[0070] In certain embodiments, the subject device 100, will further
include an element 115 for measuring an electrical current between
the first 103 and second 105 electrodes. The electrical current
measuring element 115, may be any structure, component or apparatus
that is well known in the art and that may be electrically
connected 113 to one or more components of the present invention.
The device may further include other elements of the output
generating system, including data acquisition software, an
electronic storage medium, etc.
[0071] Referring to FIG. 2B, the subject device 100, in some
embodiments, will further include an element 119 for applying an
electrical voltage between the first 103 electrode and first member
for holding a sample 107. The electrical voltage generating element
119 may be positioned anywhere relative to the substrate 101, the
nanodimensional gap 106, the first electrode 103 and the first
member for holding a sample 107. The electrical voltage generating
element 114 should be capable of ramping to establish a
time-varying voltage between the first electrode 103 and the first
member for holding a sample 107. A variety of electrical voltage
generating elements 119 may be employed with the present invention.
A number of these electrical voltage generating elements 119 are
known in the art. The electrical voltage generating element 119 has
the ability to ramp to establish the time-varying voltage between
the first electrode 103 and the first member for holding a sample
107.
[0072] In certain embodiments, the subject device 100, will further
include an element 118 for measuring an electrical current between
the first 103 electrode and the first member for holding a sample
107. The electrical current measuring element 118, may be any
structure, component or apparatus that is well known in the art and
that may be electrically connected 120 to one or more components of
the present invention. The device may further include other
elements of the output generating system, including data
acquisition software, an electronic storage medium, etc.
Fabrication of the Subject Devices
[0073] Having described representative embodiments of the device of
the invention, a description of representative embodiments of
methods of fabrication of the invention is now provided. A
non-limiting exemplary method of fabricating an embodiment of the
subject device 100 is provided in FIGS. 4A-4F, 5A-5B, and 6A-6B.
The figures are not necessarily drawn to scale. For example, the
width of the nanodimensioned gap is exaggerated in order to make it
visible at the drawing scale. In general fabrication of the subject
device 100 includes first fabricating a planar resonant tunneling
sensor and then positioning the planar resonant tunneling sensor in
a device that further includes a first member 107 for holding a
sample and a second 108 member for moving the first member 107 and
the planar resonant tunneling sensor relative to each other.
[0074] In an exemplary embodiment, fabrication of the planar
resonant tunneling sensor begins, as exemplified in FIGS. 4A and 4B
with providing a substrate 101 and forming a first insulating layer
102 atop substrate 101. The first insulating layer 102 may be
formed atop the substrate 101 by a variety of deposition method
known in art, such as, for example, TEOS oxide deposition. The
insulating layer 102, may include one or more of one of a group
including but not limited to a polymer, photoresist, SU8
photoresist, epoxy, polyimide, Parylene.RTM., a silicone polymer,
silicon dioxide, silicon nitride, silicon oxynitride, silicon-rich
silicon nitride, TEOS oxide, and plasma nitride. In some
embodiments, the insulating layer 102 comprises silicon
dioxide.
[0075] The first insulating layer 102 may be formed atop substrate
101 by a variety of deposition methods known in the art. For
example, a deposition source, such as a vacuum evaporation source
or a molecular beam epitaxy source or a sputtering source is used
to deposit the first insulating layer 102 atop substrate 101. Next,
a lithography step is performed, and etching is performed in a
dilute solution of aqua regia, comprising a mixture of hydrochloric
acid and nitric acid, to define the lateral extent of the first
insulating layer 102. Alternatively, a photolithography step may be
performed prior to the deposition step and first insulating layer
102 may be defined by means of a lift-off process.
[0076] The insulating layer 102 may comprise various shapes and
sizes. However, it must be large enough and of sufficient width to
be capable of supporting a planar resonant tunneling sensor. In
representative embodiments, the insulating layer 102 covers the
entire upper surface of substrate 101. In representative
embodiments, the insulating layer 102 has a thickness ranging from
about 0.1 .mu.m to about 5 .mu.m, including from about 0.5 .mu.m to
about 4 .mu.m, such as from about 2 .mu.m to about 3 .mu.m. In
representative embodiments, the insulating layer 102 has a
thickness of about 1 .mu.m.
[0077] The exemplary fabrication method of the planar resonant
tunneling sensor continues as shown in FIG. 4C by forming the first
electrode 103 atop a first portion of the insulating layer 102. The
first electrode 103 may be made up of a variety of electrically
conductive materials. Such materials include, but are not limited
to, metals, silicides, such as polycrystalline silicon, organic
conductors and superconductors, electrically conductive metals and
alloys of tin, copper, zinc, iron, magnesium, cobalt, nickel,
platinum, and vanadium. Other materials well known in the art that
provide for electrical conduction may also be employed. In certain
embodiments, the first electrode 103 is made of polycrystalline
silicon. In other embodiments, the first electrode 103 is made of
platinum.
[0078] The first electrode 103 may be formed atop a first portion
of the insulating layer 102 by a variety of deposition methods
known in the art. For example, a deposition source, such as a
vacuum evaporation source or a molecular beam epitaxy source or a
sputtering source is used to deposit the first electrode 103 atop a
first portion of the insulating layer 102. Next, a lithography step
is performed, and etching is performed in a dilute solution of aqua
regia, comprising a mixture of hydrochloric acid and nitric acid,
to define the lateral extent of the first electrode 103.
Alternatively, a photolithography step may be performed prior to
the deposition step and first electrode 103 may be defined by means
of a lift-off process.
[0079] The first electrode 103 may comprise various shapes and
sizes. However, it must be large enough and of sufficient width to
be capable of forming a planar resonant tunneling sensor. In
representative embodiments, the first electrode 103 has a width
ranging from about 0.5 .mu.m to about 25 .mu.m, such as from about
1 .mu.m to about 5 .mu.m. In representative embodiments, the first
electrode 103 has a thickness ranging from about 0.1 .mu.m to about
5 .mu.m, including from about 0.5 .mu.m to about 3 .mu.m, such as
from about 0.75 .mu.m to about 2 .mu.m. In certain embodiments, the
first electrode 103 has a thickness of about 1 .mu.m.
[0080] The exemplary fabrication method continues as shown in FIG.
4D by forming a spacer element 104 over the first electrode 103 and
the first insulating layer 102. The spacer element 104 may be made
of a variety of materials that are capable of providing insulation
between the first electrode 103 and the second electrode 105. Such
materials include, but are not limited to, to a polymer,
photoresist, SU8 photoresist, epoxy, polyimide, Parylene.RTM., a
silicone polymer, silicon dioxide, silicon nitride, silicon
oxynitride, silicon-rich silicon nitride, TEOS oxide, and plasma
nitride. In certain embodiments, the second insulating layer 104 is
made of silicon dioxide. The spacer element 104 may also be made up
of a variety of electrically conductive materials. Such materials
include, but are not limited to, metals, silicides, polycrystalline
silicon, organic conductors and superconductors, electrically
conductive metals and alloys of tin, copper, zinc, iron, magnesium,
cobalt, nickel, platinum, and vanadium. The spacer element 104 may
be removed, for example by means comprising chemical etching, in
the region of nanodimensioned gap 106 and extending downward to
first insulating layer 102.
[0081] The spacer element 104 may be formed atop the first
electrode 103 and the first insulating layer 102 by a variety of
deposition methods known in the art. For example, a deposition
source, such as a vacuum evaporation source or a molecular beam
epitaxy source or a sputtering source is used to deposit the spacer
element 104 atop the first electrode 103 and the first insulating
layer 102.
[0082] The spacer element 104 may comprise various shapes and
sizes. However, it must be form a covering layer on the sidewall of
first electrode 103 in the region which will later comprise
nanodimensioned gap 106. In representative embodiments, the spacer
element 104 covers the entire exposed surfaces of the first
electrode 103 and first insulating layer 102. In representative
embodiments, the spacer element 104 has a thickness ranging from
about 0.5 nm to about 10 nm, including from about 1 nm to about 9
nm, such as from about 2 nm to about 8 nm, from about 3 nm to about
7 nm, from about 4 nm to about 6 nm. In certain embodiments, the
spacer element 104 has a thickness of about 2 nm.
[0083] The exemplary fabrication method continues as shown in FIG.
4E by forming the second electrode 105 atop the spacer element 104.
In representative embodiments, the second electrode 105 is
deposited over a portion of the spacer element 104 that does not
cover the first electrode 103 and the portion of the spacer element
104 that does cover the first electrode 103, as demonstrated in
FIG. 5A (the region covering the first electrode 103 is represented
by the dashed line). The second electrode 105 may be made up of a
variety of electrically conductive materials. Such materials
include, but are not limited to, metals, suicides, polycrystalline
silicon, organic conductors and superconductors, electrically
conductive metals and alloys of tin, copper, zinc, iron, magnesium,
cobalt, nickel, platinum, and vanadium. Other materials well known
in the art that provide for electrical conduction may also be
employed.
[0084] In certain embodiments, the second electrode 105 is made of
polycrystalline silicon. In other embodiments, the second electrode
105 is made of platinum. In some embodiments, the first electrode
103 and second electrode 105 are made of the same material. In
other embodiments, the first electrode 103 and second electrode 105
are made of different materials. The second electrode 105 may
comprise various shapes and sizes. However, it must be large enough
and of sufficient width to cover the portion of the spacer element
104 that covers the edge of first electrode 103 in the region which
will later comprise nanodimensioned gap 106, as demonstrated in
FIG. 5A.
[0085] The second electrode 105 may be formed atop the spacer
element 104 by a variety of deposition methods known in the art.
For example, a deposition source, such as a vacuum evaporation
source or a molecular beam epitaxy source or a sputtering source is
used to deposit the second electrode 105 atop the spacer element
104. Next, a lithography step is performed, and etching is
performed in a dilute solution of aqua regia, comprising a mixture
of hydrochloric acid and nitric acid, to define the lateral extent
of the second electrode 105. Alternatively, a photolithography step
may be performed prior to the deposition step and second electrode
105 may be defined by means of a lift-off process.
[0086] The exemplary fabrication method continues as shown in FIG.
4F by removing a portion of the second electrode 105 and a portion
of the spacer element 104 in order to produce a planar surface. In
representative embodiments, this step will produce a planer surface
that includes a first electrode 103 and a second electrode that are
separated by a nanodimensioned gap 106, wherein the nanodimensioned
gap 106 is occupied by spacer element 104, as represented in FIG.
5B. The planarization of the surface of device may be performed by
a variety of method well known in the art that are capable of
removing a portion of the surface of an element to produce a planar
surface. In some embodiments, the planarization of the surface will
occur using a polishing or chemomechanical polishing (CMP)
protocol. In some embodiments, the spacer element 104 is removed in
the region of nanodimensioned gap 106 by means comprising a group
including but not limited to chemical etching, plasma etching, and
reactive ion etching. In some embodiments the removal of spacer
element 104 in the region of nanodimensioned gap 106 extends down
to first insulator layer 102.
[0087] The substrate 101 can then be diced by sawing to form
individual chips, not shown, and electrical connection of these
chips to an electrical circuit can be performed.
[0088] The final step in the preparation of the subject device is
the positioning of the planar resonant tunneling sensor into device
that includes a first member 107 for holding a sample and a second
member 108 for moving the first member 107 and the planar resonant
tunneling sensor relative to each other. The first member 107 can
be made of a variety of materials that are capable of holding a
sample in position above the planar resonant tunneling sensor. In
some embodiments the first member 107 is an atomic force microscope
(AFM) tip. In other embodiments the first member 107 is a scanning
tunneling microscope (STM) tip. In representative embodiments, the
first element 107 holds the sample above first electrode 103,
nanodimensioned gap 106 and second electrode 105 at a distance from
about 0.1 nm to about 100 nm, including form about 0.5 nm to about
10 nm, such as from about 1 nm to about 5 nm. The second member 108
can be made of a variety of materials to provide an element that is
capable of moving the first member 107 and the planar resonant
tunneling sensor relative to each other. In some embodiments, the
first member 107 and the second member 108 are separate units that
do not comprise a single integrated structure. In certain
embodiments, the first member 107 and second member 108 are a
single integrated structure. In representative embodiments the
first member 107 and the second member 108 are an integrated
structure, such as is found in an atomic force microscope (AFM), a
scanning tunneling microscope (STM), and the like. In further
embodiments, the first member 107 may further include an optional
insulating material 117.
[0089] It will be appreciated that the fabrication sequence
described above is by way of example only, and that there are other
techniques well known to those skilled in the art which may be used
to arrive at the same final structure. It will be appreciated also
that the use of known adhesion promoter techniques between various
layers will improve the yield of the fabrication process and the
quality of the finished nanopore chip, and the use of such adhesion
promoter techniques is assumed during the fabrication process even
where not explicitly described. For example, in some embodiments,
as demonstrated in FIGS. 6A and 6B, an adhesion-promoting layer 120
may be deposited atop the first insulating layer 102 and the spacer
element 104 prior to the deposition of the first 103 and second 105
electrode layers. In such embodiments, the adhesion-promoting layer
120 may be made up of a variety of adhesion promoting materials,
such as chromium. It will be appreciated that angled deposition
techniques used to deposit adhesion-promoting layer 120 can avoid
depositing material in the region of nano-dimensioned gap 106.
[0090] It will be appreciated that, while the present invention is
aimed toward utility in fabrication of a device including a planar
resonant tunneling sensor, it may prove to have utility for
fabrication of other devices both known and unknown. Such devices
include devices with microscale and nanoscale dimensions.
Microscale dimensions are defined to include dimensions from 100 nm
to 1 mm, and nanoscale dimensions are defined to include dimension
from 0.1 nm to 1 .mu.m.
Uses of the Subject Devices--
[0091] In general, the method of using the subject device 100 of
the present invention includes applying an electrical voltage
between the first 103 and second 105 electrodes of the device and
monitoring the electrical current between the first 103 and second
105 electrodes. The device is useful for characterizing
nanocrystals, quantum dots, and macromolecules, and advantageously
provides a degree of separation between sample preparation and
measurement. In certain embodiments, the current flowing between
the first 103 and second 105 electrode is monitored and recorded
over a period of time. Therefore, the monitoring provides a range
of values representing the fluctuation of the current flowing
between the first 103 and second 105. In other embodiments,
repeated scans of the sample are performed while different fixed
voltages are applied and the current flowing between the first 103
and second 105 electrodes is measured in order to characterize the
sample 116.
[0092] The sample 116 may comprise a variety of shapes, sizes and
materials. The shape or size of the molecule is not important, but
it must be capable of being held in position in the first member
107 for holding a sample. Exemplary samples include, but are not
limited to, nanocrystals, quantum dots, macromolecules, and the
like. A sample 116 is schematically depicted as a square in FIGS.
2A and 2B that is held in position in the first 107 member for
holding a sample. In representative embodiments, the sample 116
resides in air or vacuum, in the absence of an aqueous solvent. In
some embodiments a solvent may be present, and in some embodiments
the solvent may be an aqueous solvent.
[0093] In certain embodiments, a sample 116 held in position in a
first member 107 for holding a sample is scanned in the region
above nanodimensional gap 106 in between the first 103 and second
105 electrodes while a time-varying electrical bias is applied
between the two electrodes. As the sample 116 is moved in the space
above the nanodimensioned gap and the geometry of the resonant
tunneling spectrometer structures varies (i.e., the distance
between the sample and the second 105 electrode decreases as the
distance between the sample and first 103 electrode increases), the
current is measured and recorded. As demonstrated in FIGS. 7A-7E,
at specific voltages the incident energy and will match the signal
representative of the internal electronic band structure of the
sample.
[0094] In another embodiment, the device 100 includes a triode
structure comprising a resonant tunneling sensor, wherein the first
member 107 for holding a sample is made of a conductive material,
such as a STM tip. In such embodiments, a tunneling current due to
the phenomenon of resonant tunneling occurs from one electrode, to
the sample under test, and thence to another electrode. The
magnitude and phase of the tunneling current depend on the spatial
position and orientation of the sample under test, on the internal
electronic band structure of the sample under test, and on the
voltages applied to the three electrodes in the triode structure.
The resulting resonant tunneling spectrum provides information on
the makeup of the sample under test. Advantageously, the applied
voltage needed to obtain spectral data may be minimized. In some
embodiments, the STM tip may be coated with an insulator which sits
between the conductive portion of the STM tip and the sample under
test.
[0095] The matched-barrier resonance provides nanometer-scale
spatial resolution within the volume of the sample under test.
Additionally, the matched-barrier resonance provides an enhancement
of the resonant tunneling current, which is used as a signal
representative of the internal electronic band structure of the
sample under test. In further embodiments, the device may also be
employed in a dielectrometry mode, such as a dielectrometry sensor,
further described in U.S. Pat. No. 6,380,747 and U.S. Patent
Application No. 20020075006, the disclosures of which are
incorporated herein in their entirety.
[0096] It will be appreciated that the utility of the structures
and processes described herein has been discussed with respect to
the theory of resonant tunneling, but that the utility of these
structures and processes is in no way limited to resonant
tunneling, but instead applies also to other physical phenomena
useful for measurement and manipulation of small object including
biopolymers, including but not limited to non-resonant tunneling,
electrostatic attraction and repulsion, fluidic field effect
transistors, electrolysis, and the like. Either one or both of the
electrodes 103 and 105, or the insulator element 104 between
electrodes 103 and 105, might be coated with a monolayer of a
molecule useful for binding to or detecting a biopolymer molecule
of interest.
[0097] In certain embodiments, the subject methods also include a
step of transmitting data or results from the monitoring step, as
described above, to a remote location. By "remote location" is
meant a location other than the location at which the translocation
occurs. For example, a remote location could be another location
(e.g. office, lab, etc.) in the same city, another location in a
different city, another location in a different state, another
location in a different country, etc. As such, when one item is
indicated as being "remote" from another, what is meant is that the
two items are at least in different buildings, and may be at least
one mile, ten miles, or at least one hundred miles apart.
[0098] The preceding merely illustrates the principles of the
invention. It will be appreciated that those skilled in the art
will be able to devise various arrangements which, although not
explicitly described or shown herein, embody the principles of the
invention and are included within its spirit and scope.
Furthermore, all examples and conditional language recited herein
are principally intended to aid the reader in understanding the
principles of the invention and the concepts contributed by the
inventors to furthering the art, and are to be construed as being
without limitation to such specifically recited examples and
conditions. Moreover, all statements herein reciting principles,
aspects, and embodiments of the invention as well as specific
examples thereof, are intended to encompass both structural and
functional equivalents thereof. Additionally, it is intended that
such equivalents include both currently known equivalents and
equivalents developed in the future, i.e., any elements developed
that perform the same function, regardless of structure. The scope
of the present invention, therefore, is not intended to be limited
to the exemplary embodiments shown and described herein. Rather,
the scope and spirit of present invention is embodied by the
appended claims.
* * * * *