an overview of recent developments in nanotechnology for

8/6/2019 An Overview of Recent Developments in Nanotechnology For

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AN OVERVIEW OF RECENT

DEVELOPMENTS IN

NANOTECHNOLOGY FOR SPACESYSTEMS.


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WHY NANOTECHNOLOGY?

Advanced miniaturization, a key thrust area to enable new science andexploration missions

Ultrasmall sensors, power sources, communication, navigation,and propulsionsystems with very low mass, volume and power consumption are needed.

Nanotechnology presents a whole new spectrum of opportunities to builddevice components and systems for entirely new space architecture.

Collection of microspacecraft making a variety of measurements.


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RESEARCH FOCUS

Nanostructured thin films for infrared sensors.

Carbon nanotubes

Nanotubes- reinforced polymers. Nanostructured chemical sensors

Graphene

Inorganic nanowires.


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CARBON NANOTUBES

CNT is a tubular form of carbon with diameter as small as 1 nm.

Length: few nm to microns.

CNT is configurationally equivalent to a two dimensional graphene sheet rolled into atube.

Carbon nanotubes materials possess the chemical properties of carbon, thethermal conductivity of diamond, and the electrical conductivity of copper orsilicon.


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CNT PROPERTIES

The strongest and most flexible molecular material because of C-C covalentbonding .

Youngs modulus of over 1 TPa vs 70 GPa for Aluminum, 700 GPA for C-fiber

strength to weight ratio 500 time > for Al; similar improvements over steel andtitanium; one order of magnitude improvement over graphite/epoxy

Maximum strain ~10% much higher than any material. Electrical conductivity six orders of magnitude higher than copper

Very high current carrying capacity

Excellent field emitter


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CNT APLICATIONS

CNT based microscopy: AFM, STM

Nanotube sensors: force, pressure, chemical

Biosensors

Molecular gears, motors, actuators

Batteries, Fuel Cells: H2, Li storage

Nanoscale reactors, ion channels

Biomedical CNT quantum wire interconnects

Diodes and transistors for computing

Capacitors

Data Storage


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Atomic Force Microscopy is a powerful technique for imaging, nanomanipulation,as platform for sensor work, nanolithography...

Conventional silicon or tungsten tips wear out quickly.

CNT tip is robust, offers amazing resolution.


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NANOTUBE REINFORCED POLYMERS

Qualities such as electrical conductivity, high aspect ratio, high modulus, and highstrength make carbon nanotubes a natural candidate for use as fillers in polymer

composites for spacecraft structures.

The materiala carbon-nanotube/polyimide blend provides bulk conductivity andenvironmental stability to mitigate surface charging on satellites.

The addition of carbon nanotubes (0.54 percent by volume) to polycyanuratecomposite thin films increased the elastic modulus from 303,400 to 690,000 pounds

per square inch (psi) a 127 percent increase.


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NANOSTRUCTUREDTHIN FILMS FOR

INFRARED SENSORS

Space systems rely on sophisticated sensors for numerous military and intelligenceapplications, including surveillance, target tracking and discrimination. Current

sensor systems generally must be cooled to ultralow temperatures to enhance

operating stability and resolution . However, cryogenically cooled devices present

significant design challenges related to size, weight, power, and cost, as they are

expensive to manufacture, require frequent calibration and maintenance, andconsume appreciable amounts of power.

Infrared detectors made from pyroelectric materials (which generate a temporaryelectrical current in response to a change in temperature) have received significant

attention as a result of their stability, sensitivity, wide spectral response, and low

amount of dark current. In a pyroelectric detector, a ferroelectric absorbing layer is

used to capture radiant energy, which heats up the pyroelectric material, causing aspontaneous and reversible electric polarization and a measurable variation in the

surface charge.


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BIOSENSORS

Our interest is to develop sensors for astrobiology to study origins of life. CNT,though inert,can be functionalized at the tip with a probe molecule. Current study

uses AFM as an experimental platform.

The technology is also being used in collaboration with NCI to develop sensors for

cancer diagnostics Identified probe molecule that will serve as signature of leukemia cells, to be

attached to CNT

Current flow due to hybridization will be through CNT electrode to an IC chip.

FEATURES

High specificity

Direct, fast response

High sensitivity

Single molecule and cell signal capture.


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CHEMICAL SENSORS

Every atom in a single-walled nanotube (SWNT) is on the surface and exposed toenvironment .

Charge transfer or small changes in the charge-environment of a nanotube can

cause drastic changes to its electrical properties


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NANOWIRESMotivations for selecting Single Crystall

Low defect density, grain boundary free .Well-defined surface structuralproperties

Enhanced interfacial engineering

Predictable electron transport properties

Predictable device performance

Unique physical properties due to quantum confinement effects

Enhancement in device characteristics

Tunable electronic properties by doping

Enhancement in device characteristics

Truly bottom-up integration approach

Innovative fabrication schemes

Potential to revolutionize nano-scale science and technology


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PROTEIN NANOTUBES

Heat shock protein (HSP 60) in organisms living at high temperatures

(extremophiles) is of interest in astrobiology

HSP 60 can be purified from cells as a double-ring structure consisting of16-18 subunits. The double rings can be induced to self-assemble intonanotubes.


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GRAPHENE

Aerospace has also begun to investigate graphene as a material for advancedapplications. Graphene is a two-dimensional sheet of graphite (a carbon allotrope)with a thickness of one atomic layer. . Many labs have now isolated graphene

flakes, and measurements show the material has phenomenal electrical properties.

The high mobility of charge carriers has many potential applications for molecularelectronic devices such as room-temperature ballistic transistors and solar cells.

The extremely high conductivity has also led to applications in the realm ofchemical sensorsa device based on graphene was recently shown to achieve

single molecule sensitivity.

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One of the limitations of working with graphene is the preparation method. Thetechnique looks no more sophisticated than drawing with a piece of graphite and

repeatedly peeling it with adhesive tape until the thinnest flakes are found.

Aerospace researchers have succeeded in producing single layers of graphene andtransferring them to silicon wafers for characterization and device fabrication.

Applications could include sensors, electronic devices, batteries, and solar cells

an overview of recent developments in nanotechnology for

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