Introduction to Nano/Bio Engineering (EIEN481)Carbon Nanotube SEN-

SOR

Contents

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Reason to choose carbon nanotube sensor1

What is CNT(Carbon Nano Tube)2

Type of Sensor3

Development direction in the future4

• Recently the inherent characteristics of carbon nan-otubes such as electrical conductivity, mechanical strength, lightness, thermal conductivity and optical properties due to its structural characteristics, the electrical signal passing the wires and the electrodes of the Nano-sized leads to lots of research underway.

• Limitless value in use

• Infinitesimal small detection and Miniaturization

• Low cost

Reason to choose carbon nanotube sensor2

• Large aspect ratios• Unique properties• Finds applications in

1. Conductive plastics and adhesives

2. Energy storage

3. Efficient heat conduits

4. Structural composites

5. Biomedical devices

• Numerous electronic applications

Reason to choose carbon nanotube sensor2

What is CNT(Carbon Nano Tube)2

Extremely thin hollow cylinders made of carbon atoms.diameter is about 10,000 times smaller than a hu-man hair !Size : 0.6 to 1.8 nanometer in diameterDensity : 1.33 to 1.40 grams per cubic cen-timeterTensile strength : 45 billion pascalsResilience : Can be bent at large angles and restraightened without damageCurrent carrying capacity : Estimated at a 1 billion amps per square centimeter.

A sensor is an instrument that responds to a physical stimulus (such as heat, light, sound, pressure, magnetism, or motion)

It collects and measures data regarding some property of a phenomenon, object, or material

Sensors are an important part to any measurement and automation application

The sensor is responsible for converting some type of physical phenomenon into a quantity measurable by a data acquisition (DAQ) system

Sensor2

System Target species

Salient feature Reference

Single wall nanotubes (SWNT)

NH3 and NO2

Sensitive to 200 ppm of NO2, and 1% of NH3. Science 287 (2000)1801.

Single wall nanotubes (SWNT)

N2, He,O2, and Ar

Gas concentrations as low as 100 ppm can be detected

Appl. Phys. Lett. 83(2003) 2280.

Multi-wall carbon nan-otubes (MWCNTs)

NH3 Gas concentrations as low as 10 ppm can be de-tected. The sensor showed a reversible response of few minutes.

J. Phys. D: Appl. Phys.36 (2003) L109.

Poly(o-anisidine) (POAS) coated CNT

HCl Nine times increase in sensitivity compared to uncoated CNT

Chemical Physics Let-ters, Volume 383( 5-6) ( 2004) 617.

MWNT-SiO2 CO2, O2

and NH3

Sensor response time is approximately 45 s, 4 min, and 2 min for CO2,O2, and NH3, respectively.The sensor response is reversible for O2 and CO2 , but irreversible for NH3

IEEE Sens. J. 2 (2002)82.

Single-walled carbon nanotube (SWNT)

β-D-glucose

Senses β-D-glucose in solution phase by two distinct mechanisms of signal transduction: fluorescence and charge transfer.

Nat. Mater. 4 (2005)86.

Poly(vinylferrocene) (PVF) derivatised MWCNTs

Glucose Glucose concentration in real blood sample can be determined.

The Analyst 131 (2006)670.

CNT based Nano Sensor2

• Measures breakdown voltage to identify gas– Nanotubes lower breakdown voltage by 65%

• Gas quantities determined by current discharge• Advantages:

– Independent of Temp. and Humidity– No absorption (quick recovery)

• Disadvantages:– Not good at low concentrations(~25ppm when combined withgas chromatography)

Gas Ionization Sensor3

• Advantages– Stable– Highly sensitive (50 ppb)– Fast response time and recovery time (< 4seconds)– Sensitive to wide range of chemical vapors (19 tested)

Doped Si

SiO2SWCNT

elec-trodes

Chemical Detection with a Carbon Nanotube Capacitor3

Doped Si

SiO2

Doped Si

SiO2

Doped Si

SiO2

Doped Si

SiO2

• Much cheaper than current solid-state sensors ($100 vs. $1500)

• Scalability limited only by lithography step

CVD growth of SWNT

Photolithography to make 2 mmx 2mm interdigitated array

Get rid of excess CNT

Processing3

• Chemical sensor consisting of a single-walled carbon nanotube field effect transistor (SWCN-FET) with a nanoscale layer of sin-gle stranded DNA (SSDNA) adsorbed to the tube's outerwall. These sensors have been able to detect methanol, trimethy-lamine, propionic acid, dimethyl methylphosphonate (a simulant of sarin), and dinitrotoluene (a derivative of TNT) at the ppm level.

http://www.lrsm.upenn.edu/~nanophys/biosensors.html

DNA-Functionalized Carbon Nanotube Chemical Sensor 3

• Glucose biosensor using CNT-nanoelectrode ensembles.

• The CNT array was fabricated by growing CNTs directly on the patterned catalysts.

• The density of the CNT array can be ad-justed by changing the density of the cata-lysts.

• The GOx molecules were attached to the open-ended tips of the CNTs by forming amide linkages between their amine residues and carboxylic-acid groups on the CNT tips via carbodiimide chemistry.

• Glucose sensor based on carbon-nanotube (CNT) na-noelectrode ensembles

Glucose sensor 3

• Aim: Design, fabrication, modeling and systematic evaluation of carbon nanotube-based (CNT) NO2 gas sensor demonstrators for fire detection and exhaust gas monitoring apps.

SWNT Diameter: 1.7 and 2.2nmDevice length: 600nm

• Core concept: Individual SWNT chemical field effect transistor (Chem-FET)

• Principle: Analyte gas molecules attach and change the channel conductance as measured via Ids current

Carbon Nanotube NO2 Gas Sensors3

Closed cylinders (no dangling bonds), i.e.:• Chemically inert

robust in harsh environments• Analyte physisorbtion > chemisorption

sensor recovery is possible

What makes SWNTs suitable for chemical sensing?3

Hollow cylinders (no bulk atoms), i.e.:• All atoms are exposed

electronic props are sensitive to environment• Sensitive atoms are at surface

room temperature operation (no analyte diffusion required)

from Intechno Consulting report 2004

Chemical sensor market3

• Quantitative analysis

• Using proper equipment(SEM, TEM, AFM and so on)

• Recognizing safety and making rule

Consideration for making 4

• Intelligent sensor(Optimize property like sensitivity, selectivity itself)

• Wireless response

• Nano robotics

Journal of the Korean Society for Precision Engineering Vol. 25, No. 11, pp. 15-21

Future of CNT sensor4

Fri Mar 20, 2009 6:11am EDT

LONDON (Reuters) - Robot fish developed by British scientists are to be released into the sea off north Spain to detect pollution.If next year's trial of the first five robotic fish in the northern Spanish port of Gijon is successful, the team hopes they will be used in rivers, lakes and seas across the world.The carp-shaped robots, costing 20,000 pounds ($29,000) apiece, mimic the movement of real fish and are equipped with chemical sen-sors to sniff out potentially hazardous pollutants, such as leaks from vessels or underwater pipelines.They will transmit the information back to shore using Wi-Fi technology.Unlike earlier robotic fish, which needed remote controls, they will be able to navigate independently without any human interaction.Rory Doyle, senior research scientist at engineering company BMT Group, which developed the robot fish with researchers at Essex Uni-versity, said there were good reasons for making a fish-shaped robot, rather than a conventional mini-submarine."In using robotic fish we are building on a design created by hundreds of millions of years' worth of evolution which is incredibly energy effi-cient," he said."This efficiency is something we need to ensure that our pollution de-tection sensors can navigate in the underwater environment for hours on end."The robot fish will be 1.5 meters (nearly 5 feet) long -- roughly the size of a seal.

csim@andrew.cmu.edu Nanosensors for Chemical Analysis by Exploration Robots 18

UK team builds robot fish to detect pollution4

• Nanosensor Probes Single Living Cells

http://www.ornl.gov/ORNLReview/rev32_3/nanosens.htm

A nanosensor probe carrying a laser

beam(blue) penetrates a living cell to

detect the presence of a product indicating

that a cell has been exposed to a cancer-

causing substance.

Nanosensors in Cancer Detection Cont.4

• How does it happen?

The nano -needle is really a 50-nm-diameter silver-coated op-

tical fiber that carries a helium-cadmium laser beam. Attached

to the optical fiber tip are monoclonal antibodies that recog-

nize

and bind to BPT.http://www.ornl.gov/ORNLReview/rev32_3/nanosens.htm

Nanosensors in Cancer Detection Cont.4

• Researchers aim eventually to create nanodevices that do much more than deliver treat-ment.

• The goal – assist in imaging inside the body – recognize precancerous or cancer-

ous cells– release a drug that targets only

those cells– report back on the effectiveness of

the treatment

http://press2.nci.nih.gov/sciencebehind/nanotech/nano20.htm

Future Nanobiosensors.4

• Improving activity of gene therapy

• Oral vaccinations

• Magnetite - dextran nanoparticles for MRI diagnosis of liver, lymph node, vascular diseases

• Etc…

Future Nanosensors,cont4

Q/A