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sensing & sensors
CMU SCS RI 16722 S2009
TH 13:30 -14:50 NSH1305
Cheow Hin Sim
<[email protected]>
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Nanosensors for Chemical Analysis by Exploration Robots
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Nanosensors for Chemical Analysis by
Exploration Robots
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Nanosensors for Chemical Analysis by Exploration Robots
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Chemical Nanosensor Needs
Chemical detectors are used in applications for
Industrial: leak detection, food quality surveillance
Environmental: air and water quality
Military: anti-terrorism applications
Aerospace: identify soil and atmospheric constituents
Various sensing techniques available: optical,
electrical, mechanical…
Need to maximize the quantity, diversity, and
accuracy of information extracted to achieve
improved sensitivity, selectivity and stability
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Miniaturization
Micro technology
Nano technology
Nanostructures have high catalytic surface area: High
sensitivity, selectivity and response time
Reduction in size, weight and power consumption
Multiplexing capability to distinguish multiple chemical
species.
Shrinking technology
Rack sized
measuring
instrument
Micro Gas Chromatograph
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Nanosensors for Chemical Analysis by Exploration Robots
Hydrogen sensor
using palladium
nanoparticles
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Principle of chemical sensing
Absorption of gas/liquid molecules
Large surface to volume ratio traps pollutants
Molecules modify physical and/or chemical
properties of active layer:
Electrochemical: H-bond formation,
electrostatic interaction..
Optical: refractive index
Physical: mass..
Transduction into a measurable
signal that is proportional to
analyte concentration.
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Classification of Chemical Sensors
Heat
transfer
Conducting
pathways
Electrical
Electrochemical
reactions
Components
of a chemical/
biological
environment
Mass
loading
Thermal
Mechanical
fluorescence
Optical
Refractive
index
Non-exhaustive list…
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Conductivity Sensors
Common sensing materials: conducting polymer
composites and metal oxides and CNTs
n-type metal oxide sensor operation:
ambient O2 moelcules chemisorb onto the sensing film surface
Reducing target gas (e.g. CO) reacts with O- and release eOxidizing agents (e.g. NO2) remove more e-
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Conductive Polymer Composite
1. Vapors pass over the polymer and
swelling produces a change in resistance
2. Resistance change is measured
for each sensor.
3. Using pattern recognition algorithms, the data
is converted into a unique response pattern.
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Conductive polymer
composite
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Array Based Sensing
Sensitivity: measure of the change in output of a sensor for a change
in input.
Why do we use sensor array?
Each sensor responds to different chemicals in varying degrees
An array of sensors will give an overall response pattern that is unique for
a given chemical .
How do we use sensor array?
CO2
CO H2
S1 = {a11 a12 a13 }
S2 = {a21 a22 a23 }
S3 = {a31 a32 a33 }
What if there are more sensors than unknowns?
→ Method of pseudo-inverses
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Assignment
(a) The figure below shows two single sensor radar plots (MoO3HT and WO3) comparing their relative sensitivities to different
gases. Identify which sensor is better for identifying NO2, CO
and NH3. Explain your answer.
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Assignment
(b) The figure shows the response of a sensor array to acetone.
Calculate the overall sensitivity of the sensor array to acetone.
Explain why a sensor array is useful for identifying a mixture of
gases for this particular situation.
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Commerical Sensors
NoseChipTM
Sensor Technology:
nanocomposite sensor array
weight: ~0.5 oz
Power: nanowatts
Cyranose 320
Artinos
Sensor Technology:
nanocrystalline tin oxide gradient
microarray
Size: 3x4 mm2
power consumption@ 300oC: 1 W
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Carbon Nanotube Sensor
Hollow nanostructure and high specific surface area
provides excellent sensitivities and fast response.
Can be functionalized to reversibly adsorb molecules of
pollutants undergoing a modulation of electrical,
geometrical and optical properties.
NASA SWNT conductive gas and
organic vapor detector
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Nanomix: Sensation Technology
Nanosensors for Chemical Analysis by Exploration Robots
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CNT Field Ionization Sensors
Different gases have a
specific ionization potential.
Sharp tips of nanotubes
generate very high electric
field at low voltages.
No adsorption/desorption
involved -> fast response
Ionization gas sensor
[Rensselaer Polytechnic Institute]
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Cantilever based Sensors
Nanomechanical Sensor
Cantilever is coated with a
chemically selective layer.
Cantilever bends due to surface
stress
Deflection of cantilever can be
measured precisely by deflecting
a light beam from the surface.
Cantilever sensor array by Concentris
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Surface Acoustic Wave Sensor
A surface acoustic wave
propagates over a coated
surface.
Absorption of gas molecules
change in the mass of the sensor
coating -> change in the
resonant frequency
HAZMATCAD™ by Microsensor Systems
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Micromachining
Microfabrication using MEMs-based technology allows
minimal size, weight and power consumption.
Construction of three dimensional structures are highly
desirable for chemical and electrochemical sensors and
microsystems.
Enable ease of integration with electronic circuitry
MEMS for rapid localized temperature control in Microhotplate (NIST)
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Analysis System Architecture
Sample Acquisition
Calibration,
Self-check
Extraction,
pyrolysis
Environmental
sampling
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Data Acquisition
Analytical system
Sample
concentration
Pumps & valves
Fluidic interfaces
Analyte
separation
Chemical
detection
Chromatography
Electrophoresis
Nanosensors
Communication
Display
Refresh
Regeneration
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Chromatography
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Oxalate
Sulfate
Phosphate
Bromide
Nitrate
Fluoride
Chloride
Nitrite
Multi-component
samples are separated
in specially treated
separation columns
before measurement
with a detector.
Samples are separated
by different migration
speed inside column
due to differing
adsorption
characteristics.
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TM
µChemLab
Preconcentrator accumulates Gas chromatograph
species of interest
separates species in time SAW sensor detects gas
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Space Exploration
A range of chemical sensing technologies to measure
several parameters of interest simultaneously.
MEMs-based micro-sensor arrays
Reliability of sensor technologies
Harsh environment (during launching)
Calibration issues
Signal drifting
“Lick and stick” smart leak
detector
Broad inclusion into intelligent “smart” systems:
Supporting technologies: signal processing, communication..
“Lick and stick” technology (ease of application)
Take advantage of quantum properties of materials for ultrasensitive detection.
CNTs, nanowires,nanopores..
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Nanosensors for Chemical Analysis by Exploration Robots
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AstroBioLab for Mars Exploration
ExoMars Rover
Mobile laboratory that uses a suite of in situ instruments: Mars Organic
Detector and Oxidant detector, micro-capillary electrophoresis
analyzer.
Target compounds are amino acids and Polycyclic Aromatic
Hydrocarbons
Electronics designed for Martian ambient survivability (-145 to 100oC)
Low power consumption with broad chemical extraction ability.
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Mars Organic Detector
Uses sublimation at Mars
ambient pressure and
temperatures to release
organic components of
retrieved samples.
Specifications:
Mass:~ 2 kg
Power: 24 W
Size: 145 x 193 x 112 mm
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Highly sensitive fluorescent detection,
detects presence/ absence of amino
acids and PAH
Interfaced with microchip-based
capillary electrophoresis for
identification of amino acids
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Mars Oxidant Detector
Test the Martian samples and
environment for their ability to
degrade organic compounds
through oxidation
Monitor reaction with wellcharacterized reactants over
days/weeks exposure.
Mars Oxidant Instrument (MOI) sensor
arrays configured into a soil cup
The chemical state is
monitored by measuring
electrical resistivity via a
chemiresistor transducer.
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UK team builds robot fish to detect
pollution
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
sensors 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
University, 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
efficient," he said.
"This efficiency is something we need to ensure that our pollution
detection 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.
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References
http://www.eetimes.com/showArticle.jhtml?articleID=212000236
Liu H., Kameoka J., Czaplewski D.A., Craighead H.G., “Polymeric
Nanowire Chemical Sensor”, Nano Lett., 4(4), 2004.
Sugiyasu K. and Swager T.M., “Conducting-Polymer-Based Chemical
Sensors: Transduction Mechanisms”, Bull. Chem. Soc. Jpn., 80(11),
2074-2083 (2007).
http://www.technologyreview.com/Nanotech/19003/
http://www.sandia.gov/mstc/technologies/microsensors/micro-chemlab.html
S. Joo and R. B. Brown, “Chemical Sensors with Integrated
Electronics”, Chem. Rev. 108 (2), 2008
http://www.specs.com/products/Kamina/electronic-nose.pdf
K. Arshak, E. Moore, G. M. Lyons, F. Harris and S. Clifford, “A review
of gas sensors employed in electronic nose applications”, Sensor
Review 24 (2), 181-198, 2004
NASA Ames research Center,
http://www.nasa.gov/centers/ames/research/2007/mars_sensor.html
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References
J. Bryzek, S. Roundy, B. Bircumshaw, C. Chung, K. Castellino, J. R.
Stetter and M. Vestel, ”Marvelous MEMs”, IEEE Circuits & Devices
Mag., March/April 2006
A. Modi, N. Koratkar, E. Lass, B. Wei & P. M. Ajayan, “Miniaturized
gas ionization sensors using carbon nanotubes”, Nature 424, 171
(2003).
C. Hagleitner, A. Hierlemann, D. Lange, A. Kummer, N. Kerness, O.
Brand & H. Balters, “Smart single-chip gas sensor Microsystems”,
Nature 414, 293 (2001).
N. V. Lavrik, M. J. Sepaniak, P. G. Datskos, “Cantilever transducers
as a platform for chemical and biological sensors”, Review of
Scientific Instruments 75 (7), 2229 (2004)
Nanomix, http://www.nano.com/
Concentris, http://www.concentris.ch/
Microsensor Systems Inc.,
http://www.microsensorsystems.com/aboutus.html
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