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JNTU World Lecture 1

Nanotechnology

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The big question

What is Nanotechnology ?

It depends who you are talking to.

“What I do is nanotechnology.”

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Our definition of Nanoscience

• any ‘useful’ object whose functionality depends on at leastone dimension being on the sub-micron scale

• functionality is determined or improved by use of nanoscale

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Live more. Care less.NANO-CARE® fabric protection imparts a revolutionary, carefree quality to wrinkle resistant fabric that minimizes stains, offers superior liquid repellency and maintains wrinkle resistance. NANO-CARE® enhanced fabrics cause water and oil spills to bead up and roll off fabric without penetrating the fibers.NANO-CARE® enhanced fabrics add value to your favorite products when you are looking for the next level in easy care, wrinkle resistant fabrics. Because the performance is "built-in" on a nano or submicron scale, these features are inherent to the nature of the fabric. This "built-in" quality means permanent performance for the life of the garment, all while maintaining breathability. NANO-CARE® fabric protection enhances market-driving, wrinkle resistant fabrics with the added value of stain repellency. Your customers will look good… and so will you.KEY FEATURES

•Superior Stain, Water, And Oil Repellency•Resists Wrinkles•Breathable Fabric•Preserves Original Hand•Easy Care•Durable Performance

Nano-products

nano tennis balls(Wilson double core)

Alter/improve product performance using nano-structures

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(Seydel, Science, 300, 80, (2003))

Qdots.com

Replace organic dyes for biomedical imaging with nano-structures

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Qdots.comPrincipal Scientist Mosaic Gene Expression System Development

Job Requirements: Ph.D. or M.D. with industrial experience (total experience of 5+ years may include some academic or postdoc experience). B.S./M.S. with more extensive experience (>8/>6 years) and a proven track record of scientific achievement. Experience with developing assays in the Life Sciences or Diagnostic industry and launch of a commercial product is a requirement. Strong background in molecular biology and mathematic analyses required. Micro array and /or RT-PCR experience is desirable. Experience with statistical analyses considered a plus.

Manufacturing Scientist

Job Requirements: Advanced degree in organic or protein chemistry, biochemistry; and 0-10 years experience process development or in a research or manufacturing environment; knowledge of protein conjugation, analytical and purification techniques is highly desirable.

Manufacturing Technician, Mosaic Gene Expression Analysis System

Job Requirements: BS in the life sciences, physical sciences, or engineering with 0-2 years or relevant work experience or an AA with 4 years of relevant work experience. Manufacturing or screening experience with robotic equipment is highly desirable. Knowledge of, or experience with, gene expression analysis is considered beneficial. Must have excellent verbal and oral communication skills. This position will require accurate record keeping and adherence to standard operating procedures and batch records. The ability to contribute to process improvements and changes is highly desirable

• established industries ‘go nano’ (e.g. electronics)• novel applications, companies and industries emerge (e.g. nanotubes)• often interdisciplinaryAll

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What’s going on on the nanoscale?

(courtesy R. Ram, MIT)

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Scientific interest in the nanoscale

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PotentialGovernment expenditures for nanotechnology: • $270 Mio in 2000, $495 Mio in 2001, $961 Mio in 2004, $3.7B in 2005-08• covers all government agencies (NSF, NIH, NASA, DoE, DoD)• centers for nanotechnology (national and state level)• small business initiatives (SBIR), $70M in 2003

• Meeting global energy needs with clean solutions• Providing Abundant Clean Water Globally• Increasing Health and Longevity of Human Life• Maximizing Productivity of Agriculture• Making Powerful Information Technology Available Everywhere• Enabling the Development of Space

Foresight Challenges:

Foresight Institute: www.foresight .org• educate public about nanotechnology• ensure the beneficial implementation of nanotechnology.

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Feynman’s lecture

“There is plenty of room at the bottom.” (R. Feynman 1960)

Encyclopedia Brittanica: 80,000 pages, area: 7.5 million sq.in.pinhead: 1/16 in. diameterRequired size reduction: 25,000 (diameter)

Reduced dot size: 8nm diameter (contains 1000 atoms)

“Can we write the Encyclopedia Brittanica on the head of a pin?”

Current status of “nano-writing” technology:

E-beam lithography: resolution 10nm

Placement of atoms on surface: single atom

Yes, we can do it!(NSF)

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Fabrication and Imaging

“How do we write it?” “How do we read it?”

Fabrication methods:• Top-down: Lithography, pattern transfer, “sculpting”Problems: Definition of feature size, alignment

• Bottom-up: Self assemblyProblems: controlled arrangement, regularity

Imaging methods:• OpticalProblems: wavelength of light on micron scale

• Electron-optics:

Problems: Expensive, complicated

• Scanning probe methods

Problems: slow due to scanning(Veeco)

(Veeco)

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Scaling

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Why Scaling?

Behavior of things changes on the small scale. Possible reasons:

• geometry

• graininess

• novel effects and regimes

Consider dependence of various quantities on dimension d

dcharacteristic dimension d

How strong is a nano-sized lever? How effective is a DC motor at the nanoscale? …

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Scaling laws

volume V: mass, weight, buoyant forces, …

• surface-to-volume ratio increases as dimensions shrink

• Surface effects matter (often neglected in analyses)

• ”nanoparticles are only surface”

• look for applications where scaling is advantageous

surface S: pressure, convection, …

3dV ∝

Geometry

2dS ∝

dVS 1∝

versus

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Scaling laws

Example: Nano soccer ball

23cm 10nm

• keep total volume the same

• calculate total surface area

• 1.5x107 nano-balls

• S/V ratio 1.15x107 times higher !!!

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Scaling laws

• S/V ratio scales with number of balls N for fixed volume as

31

0

0 NVS

VS

⋅=

• same total reaction volume does not imply same reaction

• specifically: surface-dependent (catalyzed) reactions

carbon nanotube array

catalyticconverter

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MEMS and NEMS

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Definition

MEMS = Micro-Electro-Mechanical System

• component sizes between 1µm and 1mm

• achieves engineering function(s) by electromechanical means

• core elements: sensor/actuator and signal transducer

e.g. pressure sensoraccelerometer e.g. motor, mirror

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Requirements

Requirements for MEMS:

• material for µm size structures

• fabrication for µm size features (micromachining)

• interaction mechanism (scaling)

• affordable

MEMS materials:

• single crystal Si, glass• quartz, Ge, SiC, GaAs

• SOI: silicon on insulator

• GaP, InP

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MEMS fabrication

Bulk micromachining

• features are sculpted in bulk of substrate

• often wet etching

• dependence on substrate crystallography

Surface micromachining• layered structure on top of substrate

• sacrifical layers

• combination of dry/wet etching

• independent of substrate crystallography

(after Madou)

(after Madou)

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Surface micromachiningExample: ARROW waveguide fabrication (UCSC/BYU collaboration)

Silicon NitrideSilicon Dioxide

Silicon

Silicon

SiO 2

SiO 2

Silicon

metal1 2

Silicon

SiO 2

SiO 2

Silicon

metal

SiliconSilicon

SiN metal11 22

SiO2

3 43 44

SiNSiO2 air

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ApplicationsCar industry

(after Madou)

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Integrated PCR

• thermal cycling for PCR, small thermal mass• surface chemistry relevant <1µl (Si,SiN inhibit PCR)• MEMS technology (V~100pl)• external LED, integrated detector• PCR and gel electrophoresis on chip

(after Burns)

Applications

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EconomicsMarket for MEMS

(after Madou)

(after Madou)

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aphid on mirror

ratcheting actuator (1-640Hz)

MEMS mirror

MEMS mirror

6 gear planar train

Sandia MEMS devices

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NEMS

carbon nanotubes

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NEMS

• nanoscale beams have very high oscillating frequencies (see scanning microscope)

• “resonant NEMS”

tuning fork

=1-10nm

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NEMSRotational actuator

• mirror• fluid motion detector• sensor element

• CNT: large Young’s modulus• expect fres~100MHz• CNT placement with AFM• E-beam lithography to define plate• 50V to rotate plate

300nm

Applications:

500nm

SiO2

Cr/Au

d~40nm

(Fennimore et al., Nature, 2003)

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Applications I: Nano-optics

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hυ

(a) Spontaneous emission

E2

E1

(b) Fluorescence (molecules)photoluminescence (semiconductors)

hυ E2

E1

E3

Optical processes

• energy released = light emitted at discrete wavelengths• single particle detection -> suitable for nanoparticles• can design emission wavelength with size

fluorescence from CdSe/ZnS quantum dots

Emission

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Application: Fluorescence labeling in biology

• fluorescent molecule = fluorophore• selectively tag cell parts with fluorophore• locate and identify

Optical processes

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Chemically synthesized nanoparticles (dots)

• based on group II (Zn,Cd) and group VI (S,Se,Te) elements• synthesized from solution• core-shell (ZnSe/ZnS) or organic cap layer• spherical, relatively narrow size distribution• size tunable emission wavelength

Optical processes

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Application: Replacement for molecular dyes

• dots have narrower emission spectrum• larger signal• higher selectivity

Optical processes

dots mark tumorlocation

(Seydel, Science, 300, 80, (2003)) All JN

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Applications II: Magnetism

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2. Nanomagnets in magnetic storage

Magnetic storage

70 kbits/s2 kbits/in2

50 x 24” disks$10,000/Mbyte

Microdrive (2003)50 Gbits/in2

1 x 1” dia disk

4 Gbyte

757 Mbits/s61.7 Gbits/in2

5 x 3.5” disks$0.0006/Mbyte

400 Gbyte

Deskstar 7K400

Read-Write Head:Writer: electromagnet

tiny, fast, and high fieldReader: field sensor

tiny, fast, and electric

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S S S SSSSN N N N NNNt

GMR Read Sensor

InductiveWrite Element

d

W

B Recording Medium

D = 8 nm

a

Magnetic storage

disk movement

key parameters: t = 15 nm, B = 35 nm,W = 190 nm, d = 9 nm

Writing

10 nm

Grain size distribution<D> = 8.5 ± 2.5 nmGrain boundaries<d> = 1 – 1.5 nmAll

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Patterned media: digital magnetic storage

M M

`0` `1`

• only two orientations allowed• digital memory possible

• nanofabrication allows for high density

Single-domain nanomagnets

MFM

SEM

100 nm100 Gbit/in2

bit cell~130 particles

4:1

1 Tbit/in2

bit cell~13 particles

1:1

13 Tbit/in2

bit cell~1 particle

1:1

6-nm FePt Particles

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100 nm

M

courtesy T. Savas (MIT)

Nano-magneto-opticsNano-magneto-optics

M

P

• magnetization-dependent polarization rotation• optical pulses for time-resolution

E P

E Φ(M)

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dspotM

substrate

• cavity-enhanced MOKE rotation

Ein

Ln

Er0 Er1 Er2

Dielectriccoating

Signal-to-noise

• anti-reflection coating next to magnets

n n

AR coating

Signal-to-noise

• near-field collection with etched fiber tip

NSOM fiber tip

Signal-to-noise

Spatial (lateral) resolution

mag

magspot

on

offon

AAA

RR −

+Φ≈Φ

1

1

Nano-magneto-optics

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• far and near field observation of individual single-domain nanomagnets• near-field signal constant for reduced dimensions

mag

magspot

on

offon

AAA

RR −

+Φ≈Φ

1

1

b)

(i)

(ii)0.001

0.01

0.1

1

0.01 0.1 1 10

Ker

r rot

atio

n an

gle

[deg

]

magnet diameter [µm]

N. Qureshi et al. Nano Lett. 5, 1413 (2005)

SiN +NSOMSiN

Bare Ni

Nano-magneto-optics

(d) 75nm

(e) 5µm

(c) 100nm

(b) 250nm(a) 1µm

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Drug delivery

• target drugs to specific site using magnetic field• results in lower dosage• particles are injected, moved into tissue with magnetic field

Nanomagnets in biology and medicine

MTC = magnetically targeted carrier

e.g. FeRx Inc.

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Applications III: Biology

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Nucleic acids• two forms: DNA = deoxyribonucleic acid, RNA = ribonucleic acid• three building blocks: ring compound, sugar, phosphate

• sequence of nucleotides determines genetic behavior• double (ds) and single (ss) stranded; ds: T <-> A, G <-> C• 3D helix structure through hydrogen bonds

Basic biology concepts

DNA, RNA DNADNA, RNA DNA, RNA RNA

(after Prasad)

(after Bao)

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2.1 Cell biosynthesis (Central ‘dogma’ of biology)

• proteins need to be synthesized

• transcription: copy DNA onto mRNA• translation: protein synthesis according to code• ribosomes: ~20nm diameter; consist of RNA-protein complexes• no 1:1 correspondence between RNA and amino acid sequence• parts of DNA are not translated• reverse translation currently impossible

gene expression

Cellular processes

Reverse translation ???

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tRNA (E)tRNA (A)

Basic biology conceptsExample: Translation process in ribosomes

• ribosome: molecular machine• transfer nucleotide sequence of mRNA into protein sequence• numerous molecular movements in ribosome during protein synthesis

70S ribosome

30S subunit(rRNA)

50S subunit(rRNA)

ribosomalprotein

ribosomalprotein

peptide chain

tRNA (P)

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http://greenpeace.org.uk/MultimediaFiles/Live/FullReport/5886.pdf

Applications for nanoscale pharmaceuticals and medicine

Challenges in biology

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Bio-NEMS

Biology on the nanoscale

• disease detection requires protein recognition• PSA (prostate cancer protein) binds selectively to cantilever• free energy change causes deflection• sensitive at clinically relevant levels

(Nature Biotech, 19, 856)

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Electrical single DNA molecule analysis

• sense and distinguish individual DNA molecules• use biological nanopores (α-hemolysin in lipid membrane)• electronic detection of passage of individual DNA molecules

C

(Akeson, Deamer, UCSC)


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ssDNA

13 Å

dsDNA

22 Å


• passes single-stranded DNA, blocks double-stranded DNA• limited lifetime (hours)

α-hemolysin nanopore

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T TT TGCAAGC

C

CG

GTA

loop

stem

5′ 3′5′ 3′

T TT TGCAAGC

C

CT

G

GT

6bp 6bpA14

-8.2 kcal/mol∆G° : -4.3 kcal/mol

T TT TGCAAGC

C

CG

GTA

loop

stem

5′ 3′5′ 3′

T TT TGCAAGC

C

CT

G

GT

T TT TGCAAGC

C

CT

G

GT

6bp 6bpA14

-8.2 kcal/mol∆G° : -4.3 kcal/mol

• free energy sensitive to single base-pair mismatches

• mismatch appears in blockade duration

6bp 6bpA14

52%

10%

100%

1 second 10 ms

6bp 6bpA14

52%

10%

100%

1 second 10 ms

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• nanopore alternative: Focused Ion Beam etching in silicon nitride

• variable size• nano-fabricated

(Li, Harvard)


Synthetic nanopore

1 .8 n m

a b

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Molecular beacons


• MB = hairpin DNA + fluorophores at end• fluorescence quenched in hairpin state• fluorescence when hybridized to matching sequence• hybridization detection• single nucleotide mismatch sensitivity

molecularbeacon

primerhybrid

(after Tyagi)

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?microscopy withsingle-moleculesensitivity

Integration

Life happens in non-solid environments: liquids and gases!!!

microfluidics

• no planar integrated optics for liquids and gases on chip• huge potential for fully integrated devices• affects many fields, especially life sciences: medicine,biology, chemistry, molecular biology, toxicology …

Biology on the nanoscaleIntegrated single molecule optics

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Vision: light, compact biosensors with single molecule sensitivity

• planar platform• fiber-optic coupling• single molecule control• single molecule sensitivity

Liquid core waveguide

• compact• light• fast• inexpensive

Will impact both basic science and diagnostic applications


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• first hollow-core ARROW• Si-based fabrication• other substrates possible• µm cross sections, cm lengths• picoliter volumes• light guiding

(D. Yin et al., Opt. Express 12, 2710 (2004)D. Yin et al., Appl. Phys. Lett. 85, 3477 (2004))

ARROW: AntiResonant Reflecting Optical Waveguides

Mode image at output facet (see left)

Hollowcore


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Solid-core ARROW

excitation

signal

Liquid-core ARROW

xy z 20µm

• intersecting waveguide arrays• excitation volume ~100 fl• fluorescence detection with fully planar beam geometry• single molecule sensitivity

3.1 104

3.2 104

3.3 104

3.4 104

3.5 104

3.6 104

-1 0 1 2 3 4 5 6

Phot

on c

ount

s

Approximate number of molecules

(H. Schmidt et al., JSTQE 11, 519 (2005)D. Yin et al., submitted)

SEM image of intersecting solid and hollow-coreARROW waveguides

Detected fluorescence vs. # of moleculesIn excitation volume


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PMMAreservoir

Pump waveguide

Liquid-core waveguide

• liquid core connected to reservoirs• 10µl fluidic reservoirs• demonstrated integrated platform


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V

- 5 0

0

5 0

1 0 0

1 5 0

2 0 0

2 5 0

3 0 0

- 2 0 0 2 0 4 0 6 0 8 0 1 0 0 1 2 0

I [nA

]

VD C

[ V ]

• demonstrated electrophoretically controlled fluorescence

- 0 . 2

0

0 . 2

0 . 4

0 . 6

0 . 8

1

- 0 . 1

- 0 . 0 5

0

0 . 0 5

0 . 1

4 0 0 4 0 5 4 1 0 4 1 5 4 2 0

Fluo

resc

ence

(V) Voltage(V)

T i m e [ s ]

V=0

V=200V

st 12=∆v=0.3mm/s

Integrated device on measurement stage:Pt wires for electrical signal, fiber for fluorescence

Top: current vs. voltageBottom: Electrical (blue) and optical (red) signals detected


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Multiple cells on chip(multiple analytes, single pump)

Integration of detector

Integration of filter

Integration of source

• Integration with larger microfluidic system• Integration with microelectronics• …

detector source

integrated DBR filters


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JNTU World Lecture 1All JN

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