Nanosensors for structural monitoring in civil engineering · Nanosensors and civil enginnering...
Transcript of Nanosensors for structural monitoring in civil engineering · Nanosensors and civil enginnering...
Nanosensors and civil enginneringMonitoring pore sizes with ultrasounds
Monitoring pore humidity with CNTFET
Nanosensors for structural monitoring in civilengineering
New insight on promising carbon nanotubes devices
B. Lebental1 F. Bourquin1 E. Norman2 C. S. Cojocaru2
A. Ghis3
1Universite Paris-EST, IFSTTAR, Paris, 75015, FRANCE
2LPICM, Ecole Polytechnique, Palaiseau, 91128, France
3CEA-LETI, Minatec Campus, Grenoble, 38000, FRANCE
NDCM-XII
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Nanosensors and civil enginneringMonitoring pore sizes with ultrasounds
Monitoring pore humidity with CNTFET
Nanotechnologies in the construction sector : why ?
Nanotechnologies :
Already plenty of (niche)productsGlobal market : 2500 B$ in2015
⇒ Goal : finding large marketopportunities
Construction sector :
More than 10 % of EuropeanGDPToward ’green’ construction(and cost reduction)
⇒ A new priority : improvingstructural service expectancy
Market of nanotechnologies 1Green roofing
1. Lux Research Inc., 2010
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Nanosensors and civil enginneringMonitoring pore sizes with ultrasounds
Monitoring pore humidity with CNTFET
Concrete materials : degradations and durability
1. Baroghel-Bouny, Tech. Ingenieur, 2005
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Various degradation processes
Corrosions, cracks, swelling...Origin : particules and gas transport within microporosity
⇒ To control durability, one needs tomonitor continuously microporosity
Degradations caused by internal swelling 1
Concrete microporosity
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Monitoring microporosity with nanosensors
Current monitoring solutions : large sensors with mmresolution at best
⇒ Challenge : to obtain pore by pore (µm) resolution⇒ Solution : Monitoring with 1 µm size nanosensors
We consider two parameters varying during service lifePore size : 10 nm to 10 µmHumidity : 70 % to 100 % relative humidity (RH)
⇒ determine gaseous/ionic transport parameters ⇒ Durability
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Nanosensors and civil enginneringMonitoring pore sizes with ultrasounds
Monitoring pore humidity with CNTFET
Carbon nanotubes based ultrasonic transducer
Device concept : µ-cMUT 1 :Vibrating membrane of aligned carbon nanotubes1 µm size ⇒ 10 times smaller than existing US transducers
⇒ How does ultrasonic monitoring work at the microscale ?
⇒ How does one prototype a US microtransducer ?
1. B. Lebental et al., 2008, Patents EN 08 57927 and EN 08 57928
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Nanosensors and civil enginneringMonitoring pore sizes with ultrasounds
Monitoring pore humidity with CNTFET
Device modelling
Numerical identification of the quantities the µ-cMUT mightbe sensitive to :
Original elasto-acoustic problem in microfluidics 1
⇒ Development of an original numerical method 2
1. Beltman, J. Sound Vib., 227, 555-586, 1999
2. Lebental and Bourquin, J. Sound Vib., submitted 2009
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Nanosensors and civil enginneringMonitoring pore sizes with ultrasounds
Monitoring pore humidity with CNTFET
Device modelling
Numerical identification of the quantities the µ-cMUT mightbe sensitive to :
Original elasto-acoustic problem in microfluidics 1
⇒ Development of an original numerical method 2
1. Beltman, J. Sound Vib., 227, 555-586, 1999
2. Lebental and Bourquin, J. Sound Vib., submitted 2009
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Nanosensors and civil enginneringMonitoring pore sizes with ultrasounds
Monitoring pore humidity with CNTFET
Elasto-acoustic problem
2D non-adimensionnal fluid-structure problem (well-posed) :
Clamped plate in small displacement : d s
Convection-less, flow-less newtonian fluid : (p,uf )
1A∂tp + div uf = 0 sur Ω
Mass conservation∂tuf = − 1
M2 grad p + 1Re2,r
grad div uf + 2Rer
div e(uf ) sur Ω
Momentum conservation−g1d
s + ap∂ttds + rp∂yyyyd
s = g0 + n.σ(p,uf ).n sur Γs
Plate equationuf
y = 0 and ufx = ∂td
s sur Γs
Dirichlet boundary conditionuf = 0 sur Γf
Dirichlet boundary conditiond s(0) = d s(1) = ∂yd
s(0) = ∂yds(1) = 0 + C .I .
Clamped plate boundary condition
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Nanosensors and civil enginneringMonitoring pore sizes with ultrasounds
Monitoring pore humidity with CNTFET
Our sensor concept : a microsonar
In air : large amplitude ; low sensitivity to geometry
In water : low amplitude BUTHigh sensitivity to depth : f1 ∝ l−1 1
Even with other variable parameters (width, rugosity...)
⇒ A microsonar : Measurement of water-filled pore depth
⇒ Monitoring of content and size of micropores
1. Lebental et al., EJECE 2011, 4, 649-662
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Monitoring pore humidity with CNTFET
Prototyping our microsonar
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Aligned deposition of SWNT
SWNT anchoring
Membrane release
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Applicative relevance
Ultra-thin membranes ⇒ good sensitivity to pore features
Large amplitude of vibrations measured ⇒ good transductionefficiency
⇒ Good candidate for in-situ monitoring of pore size
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Nanosensors and civil enginneringMonitoring pore sizes with ultrasounds
Monitoring pore humidity with CNTFET
Carbon nanotubes field-effect transistor
Nanotube network as semi-conducting channel of a transistorFabricated by low-density deposition of SWNT on an insulatoratop gate electrodeCNTFET known to be highly sensitive to humidity :a drawback for electronics, an opportunity to us
⇒ CNTFET humidity sensor for micropores
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Nanosensors and civil enginneringMonitoring pore sizes with ultrasounds
Monitoring pore humidity with CNTFET
Hysteresis sensitivity to humidity
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Electrical features reproducibly sensitive to humidity
Ion, Ioff , Hysteresis,...Attributed to adsorption on silicon and on metalEspecially at high humidity
⇒ Well suited for high RH environment such as concrete
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Conclusions
Fabrication and evaluation of two promising sensing elementsVibrating CNT membranes for ultrasonic micropore monitoringCNTFET for humidity measurements in micropores
⇒ Two examples among various novel sensing opportunitiesProspects :
Integration into embeddable sensing units : smart aggregatesBenchmarking in the target environment : project Sense-citya real-scale benchmarking facility to be available in the nextfew years for (your ?) sensors dedicated to urbanmeasurement : buildings, infrastructures, networks...
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Nanosensors and civil enginneringMonitoring pore sizes with ultrasounds
Monitoring pore humidity with CNTFET
Acknowledgments
Thank you for your attention !
Thanks to all my coworkers !
CEA-LETI, Minatec : Anne Ghis, Jean-Marc Fabbri, NawresSridi, Ariane Meguekam Sado, Philippe Renaux, NicolasCHevalier, Elisabeth Delevoye, Jean-Christophe GabrielLPICM, Ecole Polytechnique (+NanoCarb) : Evgeny Norman,Costel Cojoacaru, Louis Gorintin, Paolo BondavalliIFSTTAR Paris (LCPC) : Frederic Bourquin, Jean-MarieCaussignac
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