csim@andrew.cmu.edu 1

sensing & sensorsCMU SCS RI 16722 S2009

TH 13:30 -14:50 NSH1305

Cheow Hin Sim <csim@andrew.cmu.edu>

Nanosensors for Chemical Analysis by Exploration Robots

csim@andrew.cmu.edu 2

Nanosensors for Chemical Analysis by Exploration Robots

Nanosensors for Chemical Analysis by Exploration Robots

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Chemical Nanosensor NeedsChemical detectors are used in applications for

Industrial: leak detection, food quality surveillance Environmental: air and water qualityMilitary: anti-terrorism applicationsAerospace: 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

Nanosensors for Chemical Analysis by Exploration Robotscsim@andrew.cmu.edu

Miniaturization

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Micro technology Nano technology

Nanostructures have high catalytic surface area: High sensitivity, selectivity and response timeReduction in size, weight and power consumptionMultiplexing capability to distinguish multiple chemical species.

Micro Gas ChromatographHydrogen sensor using palladium nanoparticles

Rack sized measuring instrument

Shrinking technology

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Principle of chemical sensingAbsorption 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 indexPhysical: mass..

Transduction into a measurable signal that is proportional to analyte concentration. 

Nanosensors for Chemical Analysis by Exploration Robotscsim@andrew.cmu.edu

Classification of Chemical Sensors

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Mass loading Mechanical

Conducting pathways

Electrochemical reactions

Electrical

Refractive index

fluorescence

Optical

Heat transfer

Thermal

Non-exhaustive list…

Conductivity Sensors

Common sensing materials: conducting polymer composites and metal oxides and CNTsn-type metal oxide sensor operation:

ambient O2 moelcules chemisorb onto the sensing film surfaceReducing target gas (e.g. CO) reacts with O-

and release e-

Oxidizing agents (e.g. NO2) remove more e-

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8Nanosensors for Chemical Analysis by Exploration Robotscsim@andrew.cmu.edu

Conductive Polymer Composite

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.

Array Based SensingSensitivity: 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 degreesAn array of sensors will give an overall response pattern that is unique for a given chemical .

How do we use sensor array?

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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CO2 CO H2

Assignment

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(a) The figure below shows two single sensor radar plots (MoO3-HT and WO3) comparing their relative sensitivities to different gases. Identify which sensor is better for identifying NO2, CO and NH3. Explain your answer.

Assignment

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(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.

Commerical Sensors

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NoseChipTM

Sensor Technology: nanocomposite sensor array weight: ~0.5 oz

Power: nanowatts

ArtinosSensor Technology: nanocrystalline tin oxide gradient microarray

Size: 3x4 mm2

power consumption@ 300oC: 1 W

Cyranose 320

Carbon Nanotube SensorHollow 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.

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Nanomix: Sensation Technology

NASA SWNT conductive gas and organic vapor detector

CNT Field Ionization Sensors

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Ionization gas sensor [Rensselaer Polytechnic Institute]

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

Cantilever based Sensors

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

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HAZMATCAD™ by Microsensor Systems

Surface Acoustic Wave Sensor

Cantilever is coated with a chemically selective layer.Cantilever bends due to surface stressDeflection of cantilever can be measured precisely by deflecting a light beam from the surface.

Cantilever sensor array by Concentris

Nanomechanical Sensor

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

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Micromachining

MEMS for rapid localized temperature control in Micro-hotplate (NIST)

Data AcquisitionSample Acquisition

Analysis System Architecture

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Analytical system

Analyte separation

Chemical detection

Pumps & valvesFluidic interfaces

ChromatographyElectrophoresis

Nanosensors

Sample concentration

Environmental sampling

Extraction,pyrolysis

Calibration,Self-check

Refresh Regeneration

Commu-nication

Display

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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.

ChromatographyFl

uorid

eC

hlor

ide N

itrat

eB

rom

ide

Phos

phat

e

Nitr

ite

Sulfa

te

Oxa

late

Nanosensors for Chemical Analysis by Exploration Robots

µChemLabTM

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Preconcentrator accumulates species of interest

Gas chromatograph separates species in time SAW sensor detects gas

Space ExplorationA range of chemical sensing technologies to measure several parameters of interest simultaneously.

MEMs-based micro-sensor arrays

Reliability of sensor technologiesHarsh environment (during launching)Calibration issuesSignal drifting

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 ultra-sensitive detection.

CNTs, nanowires,nanopores..

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“Lick and stick” smart leak detector

AstroBioLab for Mars Exploration

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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.

Mars Organic Detector

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Specifications:Mass:~ 2 kgPower: 24 WSize: 145 x 193 x 112 mm

Uses sublimation at Mars ambient pressure and temperatures to release organic components of retrieved samples.

Highly sensitive fluorescent detection, detects presence/ absence of amino acids and PAH

Interfaced with microchip-based capillary electrophoresis for identification of amino acids

Mars Oxidant Detector

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Mars Oxidant Instrument (MOI) sensor arrays configured into a soil cup

Test the Martian samples and environment for their ability to degrade organic compounds through oxidation

Monitor reaction with well-characterized reactants over days/weeks exposure.

The chemical state is monitored by measuring electrical resistivity via a chemiresistor transducer.

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.

UK team builds robot fish to detect pollution

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Referenceshttp://www.eetimes.com/showArticle.jhtml?articleID=212000236Liu 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-chem-lab.htmlS. Joo and R. B. Brown, “Chemical Sensors with Integrated Electronics”, Chem. Rev. 108 (2), 2008http://www.specs.com/products/Kamina/electronic-nose.pdfK. 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, 2004NASA Ames research Center, http://www.nasa.gov/centers/ames/research/2007/mars_sensor.html

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ReferencesJ. Bryzek, S. Roundy, B. Bircumshaw, C. Chung, K. Castellino, J. R. Stetter and M. Vestel, ”Marvelous MEMs”, IEEE Circuits & Devices Mag., March/April 2006A. 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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