µµS GS GUniversitàUniversità deglidegli StudiStudi didi CataniaCatania
FacoltàFacoltà didi IngegneriaIngegneriaDipartimentoDipartimento didi IngegneriaIngegneria ElettricaElettrica ElettronicaElettronica
e e deidei SistemiSistemi
Residence Times Difference (RTD) Residence Times Difference (RTD) -- Fluxgate Fluxgate MagnetometerMagnetometer
IngIng. Carlo Trigona. Carlo Trigona
A.A. 2007/2008
µµS GS GOutlineOutlineClassification of magnetometersClassification of magnetometers
Magnetometers for biomedical applicationsMagnetometers for biomedical applications
RTRT--Fluxgate Fluxgate
Working principleWorking principle
Expressions of RTD and SensitivityExpressions of RTD and Sensitivity
Fluxgate technologyFluxgate technology
PCB FR4PCB FR4
“Wire”“Wire”
Magnetic particles and Magnetic particles and biosystemsbiosystems
SetSet--up up
ResultsResults
Volcanic ash detectionVolcanic ash detection
SetSet--up up
ResultsResults
ConclusionConclusionCarlo Trigona A.A. 2007Carlo Trigona A.A. 2007--20082008
µµS GS GMagnetometersMagnetometers: : classificationclassification
MagneticMagnetic fieldfield sensorssensors
MagnetometersMagnetometers GaussmetersGaussmeters
VectorVector ScalarScalar
Hall effectMagnetoresistiveMagnetodiodeMagnetotransistor
Proton precessionOptically pumped
H < 1mTH < 1mT H > 1mTH > 1mT
SQUIDFluxgateMagnetoresistance
Carlo Trigona A.A. 2007Carlo Trigona A.A. 2007--20082008
µµS GS GMagnetometersMagnetometers: : biomedicalbiomedical applicationsapplications
EarthEarth fieldfield
1010--1515 1010--1212 1010--99 1010--66
LTS SQUID (4.2 K)LTS SQUID (4.2 K)
HTS SQUID (77 K)HTS SQUID (77 K)
FluxgateFluxgate (300 K)(300 K)
BrainBrain
MagneticMagnetic
immunoassayimmunoassay
HeartHeart
[T][T]
MagnetoresistanceMagnetoresistance
Carlo Trigona A.A. 2007Carlo Trigona A.A. 2007--20082008
µµS GS GMagnetometersMagnetometers: : biomedicalbiomedical applicationsapplications
EarthEarth fieldfield
1010--1515 1010--1212 1010--99 1010--66
LTS SQUID (4.2 K)LTS SQUID (4.2 K)
HTS SQUID (77 K)HTS SQUID (77 K)
FluxgateFluxgate (300 K)(300 K)
BrainBrain
MagneticMagnetic
immunoassayimmunoassay
HeartHeart
[T][T]
MagnetoresistanceMagnetoresistance
Carlo Trigona A.A. 2007Carlo Trigona A.A. 2007--20082008
µµS GS GFluxgateFluxgate vs. SQUIDvs. SQUIDFluxgateFluxgate SQUIDSQUID
•Range [T]: 10-10 to 10-4
•Resolution [pT]: 100
•Bandwidth: dc to 2 x 103 Hz
•Low cost
•Low power
•Robust and simple system
•Operative temperature: -50 to +80°C
•Small size and weight
•Range [T]: 10-15 to 10-4
•Resolution [pT]: 0.1
•Bandwidth: dc to 5 Hz
•High cost
•Low noise
•Complex system
•Operative temperature: cryogenic
•Sophisticated applications
Carlo Trigona A.A. 2007Carlo Trigona A.A. 2007--20082008
µµS GS GRTDRTD--FluxgateFluxgate
0 2000 4000 6000 8000 1000
-0.5 -0.4 -0.3 -0.2 -0.1
0
0.1 0.2 0.3 0.4 0.5
T+ T-
0 2000 4000 6000 8000 1000
-0.5 -0.4 -0.3 -0.2 -0.1
0
0.1 0.2 0.3 0.4 0.5
T+ T-
Vout
(V)
N (samples)
( ) ⎥⎦⎤
⎢⎣⎡ ++
−=k
HxHexk
xtxU coshln
2,
2
x
txU
k
HxHexx
dt
dx
∂∂
−≡⎥⎦⎤
⎢⎣⎡ ++
+−=),(
tanhτ
Carlo Trigona A.A. 2007Carlo Trigona A.A. 2007--20082008
RTD=RTD= TT++--TT-- Residence Time Residence Time DifferenceDifference
µµS GS GRTDRTD--FluxgateFluxgateBiasBiassignalsignal
Hc
- Hc
+Msat
-Msat
FluxgateFluxgate output output waveformwaveform
Time
Carlo Trigona A.A. 2007Carlo Trigona A.A. 2007--20082008
µµS GS GRTDRTD--FluxgateFluxgate
The principle of RTD Fluxgate is to exploit the information carrThe principle of RTD Fluxgate is to exploit the information carried by the time ied by the time position of spikes in the position of spikes in the VoutVout signal. Time intervals, signal. Time intervals, T+T+ and and TT--, defined by two , defined by two successive peaks represent times spent by the core magnetizationsuccessive peaks represent times spent by the core magnetization in the two in the two steady states. These time intervals are called Residence Times. steady states. These time intervals are called Residence Times. The Residence The Residence Time Difference is the quantity RTD=Time Difference is the quantity RTD= T+T+ -- TT--. .
Carlo Trigona A.A. 2007Carlo Trigona A.A. 2007--20082008
µµS GS GRTDRTD--FluxgateFluxgateIfIf wewe considerconsider the the timestimes: t: t11, t, t22, t, t33, , it’it’s s possiblepossible toto writewrite::
( )( )
τ+=−=+
=+
13
22
11
:
:
tt
HtHHt
HtHHt
CeX
CeX
WrtingWrting the the equationsequations in the case of a in the case of a sinusoidalsinusoidal biasbias signalsignal of of amplitudeamplitudeand and frequencyfrequency wewe obtainobtain::
eHτ1
( )
CeX
CeX
HtHH
HtHH
−=⎟⎟⎠
⎞⎜⎜⎝
⎛⎟⎠⎞
⎜⎝⎛ −−
=+
2sinˆ
sinˆ
2
1
τω
ω
InvertingInverting the the functionsfunctions andand
wewe havehave the the expressionsexpressions::
( )1sin tω ⎟⎟⎠
⎞⎜⎜⎝
⎛⎟⎠⎞
⎜⎝⎛ −
2sin 2
τω t
Carlo Trigona A.A. 2007Carlo Trigona A.A. 2007--20082008
µµS GS GRTDRTD--FluxgateFluxgate
τω
τω
ω
+⎟⎟⎠
⎞⎜⎜⎝
⎛ −=
+⎟⎟⎠
⎞⎜⎜⎝
⎛ +=
⎟⎟⎠
⎞⎜⎜⎝
⎛ −=
e
XC
e
XC
e
XC
H
HHt
H
HHt
H
HHt
ˆarcsin
1
2ˆarcsin
1
ˆarcsin
1
3
2
1
2ˆarcsin
ˆarcsin
1
2ˆarcsin
ˆarcsin
1
23
12
τω
τω
+⎥⎥⎦
⎤
⎢⎢⎣
⎡⎟⎟⎠
⎞⎜⎜⎝
⎛ +−⎟⎟⎠
⎞⎜⎜⎝
⎛ −=−=
+⎥⎥⎦
⎤
⎢⎢⎣
⎡⎟⎟⎠
⎞⎜⎜⎝
⎛ −−⎟⎟⎠
⎞⎜⎜⎝
⎛ +=−=
−
+
e
XC
e
XC
e
XC
e
XC
H
HH
H
HHttT
H
HH
H
HHttT
The The expressionsexpressions of Residence Time of Residence Time differencedifference and and SensitivitySensitivity are:are:
⎥⎥⎦
⎤
⎢⎢⎣
⎡⎟⎟⎠
⎞⎜⎜⎝
⎛ −−⎟⎟⎠
⎞⎜⎜⎝
⎛ +=−= −+
e
XC
e
XC
H
HH
H
HHTTRTD
ˆarcsin
ˆarcsin
2
ω
⎥⎥⎥⎥⎥
⎦
⎤
⎢⎢⎢⎢⎢
⎣
⎡
⎟⎟⎠
⎞⎜⎜⎝
⎛ −−
+
⎟⎟⎠
⎞⎜⎜⎝
⎛ +−=
∂∂
=22
ˆ1
ˆ/1
ˆ1
ˆ/1
2
e
e
e
e
H
HxHc
H
H
HxHc
H
RTDHx
Sω
Carlo Trigona A.A. 2007Carlo Trigona A.A. 2007--20082008
µµS GS GFluxgateFluxgate: PCB FR4 : PCB FR4 technologytechnology
MetglasMetglas Core Core
The The patternedpatterned MetglasMetglas isis alignedaligned respectrespectthe the twotwo FR4 FR4 layerslayers
The The patternedpatterned metal metal layerslayers are are alignedaligned toto the the structurestructure accordingaccording toto
layout designlayout design
The The wholewhole fivefive layerslayers are are pressedpressed, , whilewhile heatingheating the the wholewhole system up system up
toto 200°200°
FinallyFinally the the viasvias formationformation betweenbetween the the
lowerlower and upper and upper layerlayer letlet toto completecomplete the the windingswindings forfor the the coilscoils
Carlo Trigona A.A. 2007Carlo Trigona A.A. 2007--20082008
µµS GS G
FR4 FR4 technologytechnology SensibilitySensibility: 0.2: 0.2µµs/nTs/nT
Noise level: 5Noise level: 5µsµs
Absorbed current: 40 Absorbed current: 40 mAppmApp
FluxgateFluxgate: PCB FR4 : PCB FR4 technologytechnology
Carlo Trigona A.A. 2007Carlo Trigona A.A. 2007--20082008
µµS GS GFluxgateFluxgate: PCB FR4 : PCB FR4 technologytechnologyCharacterization
DC Magnetic shield
Solenoid
Fluxgate
The Automatic calibration system has been implemented with a set of instrument driven by labview
The RTD has been calculated by post elaborate the output signals with MatLab
0 10 20 30 40 500
1
2
3
4
5
6
7
8
9
10
Observation Time [s]
Res
olu
tion
[nT
]
0 10 20 30 40 500
1
2
3
4
5
6
Observation Time [s]
Se
nsi
tivity
[us/
nT]
Carlo Trigona A.A. 2007Carlo Trigona A.A. 2007--20082008
µµS GS GFluxgateFluxgate: PCB FR4 : PCB FR4 technologytechnologyCharacterization
DC Magnetic shield
Solenoid
Fluxgate
The Automatic calibration system has been implemented with a set of instrument driven by labview
The RTD has been calculated by post elaborate the output signals with MatLab
Carlo Trigona A.A. 2007Carlo Trigona A.A. 2007--20082008
µµS GS G
““wirewire ” ” technologytechnology can can bebe usedusedtoto localizelocalize micromicro--entitiesentities and and ““punctualpunctual” ” magneticmagnetic fieldfield
FluxgateFluxgate: “: “wirewire” ” technologytechnology
Core: 100 Core: 100 µµmm
CoilsCoils: 100 : 100 µµmm
Carlo Trigona A.A. 2007Carlo Trigona A.A. 2007--20082008
µµS GS G
PrimaryPrimary: 30+30 : 30+30 coilscoils
Secondary: 60 coilsSecondary: 60 coils
FluxgateFluxgate: “: “wirewire” ” technologytechnology
PrimaryPrimary: 1000 : 1000 coilscoils
Secondary: 1000 coilsSecondary: 1000 coils
Carlo Trigona A.A. 2007Carlo Trigona A.A. 2007--20082008
µµS GS GFluxgateFluxgate: “: “wirewire” ” technologytechnologyCharacterization
The Automatic calibration system has been implemented with a set of instrument driven by labview
The RTD has been calculated by post elaborate the output signals with MatLab
Carlo Trigona A.A. 2007Carlo Trigona A.A. 2007--20082008
µµS GS GFluxgateFluxgate: “: “wirewire” ” technologytechnologyCharacterization
The Automatic calibration system has been implemented with a set of instrument driven by labview
The RTD has been calculated by post elaborate the output signals with MatLab
Carlo Trigona A.A. 2007Carlo Trigona A.A. 2007--20082008
MagneticMagnetic particlesparticles: : ImmunoImmuno--assayassay
Detection Detection techniquestechniques
RemanenceRemanence of of magneticmagneticparticlesparticles
RelaxationRelaxation time of time of magneticmagnetic particlesparticles
AntibodyAntibody MagneticMagnetic CoreCore
µµS GS G
Carlo Trigona A.A. 2007Carlo Trigona A.A. 2007--20082008
MagneticMagnetic particlesparticles: : ImmunoImmuno--assayassay µµS GS G
Carlo Trigona A.A. 2007Carlo Trigona A.A. 2007--20082008
MagneticMagnetic particlesparticles: CM: CM--1010--10 10 SpherotechSpherotech
DiameterDiameter: 1: 1÷÷1.4 1.4 µµmm unit: 10mlunit: 10ml
%W%W/V: 2.5/V: 2.5
µµS GS G
Carlo Trigona A.A. 2007Carlo Trigona A.A. 2007--20082008
ExperimentalExperimental SetSet--upup (I) (I) µµS GS G
Carlo Trigona A.A. 2007Carlo Trigona A.A. 2007--20082008
ExperimentalExperimental SetSet--upup (I) (I) µµS GS G
Carlo Trigona A.A. 2007Carlo Trigona A.A. 2007--20082008
ExperimentalExperimental SetSet--upup (I): (I): circuitcircuit µµS GS G
Carlo Trigona A.A. 2007Carlo Trigona A.A. 2007--20082008
ResultsResults
Detection of Detection of magneticmagnetic particlesparticles
RTD RTD variationvariation, , functionfunction of of distancedistance and and numbernumber of of particlesparticles
µµS GS G
Carlo Trigona A.A. 2007Carlo Trigona A.A. 2007--20082008
DDRTD=7RTD=7.143.143 µsµs ~~28002800 particlesparticles
~53*53 particles ≈2809 particles
1 particle CM10-10 ~ 1 µm
1 µm * 53= 0.053 mm
Surface area ≈ 1/20 mm2
ResultsResults µµS GS G
Carlo Trigona A.A. 2007Carlo Trigona A.A. 2007--20082008
11µµll
NN
NNSS
SS
1µl spot
ExperimentalExperimental SetSet--upup (II) (II)
MagneticMagnetic particlesparticles forfor DNA DNA sequencingsequencing
µµS GS G
Carlo Trigona A.A. 2007Carlo Trigona A.A. 2007--20082008
ExperimentalExperimental SetSet--upup (II) (II)
Glass support for fluxgate coils
µµS GS G
Carlo Trigona A.A. 2007Carlo Trigona A.A. 2007--20082008
ResultsResults µµS GS G
The experiment has been conduced by taking several observations The experiment has been conduced by taking several observations of the of the fluxgate output for various spot sizes (obtained via the depositfluxgate output for various spot sizes (obtained via the deposition of ion of different known fluid volumes ranging from 0.5different known fluid volumes ranging from 0.5µµl to 4l to 4µµl). Each spot is l). Each spot is maintained in the measuring position for 300 seconds. maintained in the measuring position for 300 seconds.
Carlo Trigona A.A. 2007Carlo Trigona A.A. 2007--20082008
ResultsResults µµS GS G
RTD variation RTD variation obtained via the deposition of different known fluid obtained via the deposition of different known fluid volumes ranging from 0volumes ranging from 0µµl to 4l to 4µµl.l.
Carlo Trigona A.A. 2007Carlo Trigona A.A. 2007--20082008
ExperimentalExperimental SetSet--upup (III) (III)
System System forfor volcanovolcano particlesparticles detectiondetection
MagneticMagnetic particlesparticles
µµS GS G
Carlo Trigona A.A. 2007Carlo Trigona A.A. 2007--20082008
ExperimentalExperimental SetSet--upup (III) (III)
Volcano particles
100 µm core
Primary: 1000 coils 100 µm
Secondary: 1000 coils 100 µm
µµS GS G
Carlo Trigona A.A. 2007Carlo Trigona A.A. 2007--20082008
ResultsResults
WithWith magneticmagneticparticlesparticles
WithoutWithout magneticmagneticparticlesparticles
µµS GS G
Carlo Trigona A.A. 2007Carlo Trigona A.A. 2007--20082008
ExperimentalExperimental SetSet--upup (IV) (IV) µµS GS G
The experimental setThe experimental set--up consists of a RTDup consists of a RTD--Fluxgate magnetometer, operated Fluxgate magnetometer, operated with a sinusoidal bias signal @80Hz and 20 with a sinusoidal bias signal @80Hz and 20 mAppmApp of amplitude , a permanent of amplitude , a permanent magnet is used to polarize Etna volcanic ash (0.5 mm of diametermagnet is used to polarize Etna volcanic ash (0.5 mm of diameter--year of year of eruption 2001) contained in a plastic tube.eruption 2001) contained in a plastic tube.
FluxgateVolcanic ash
PermanentMagnet
Carlo Trigona A.A. 2007Carlo Trigona A.A. 2007--20082008
ResultsResults µµS GS G
The experiment has been conduced by observing the Fluxgate outpuThe experiment has been conduced by observing the Fluxgate output signal for t signal for different values of volcanic particle numbers. different values of volcanic particle numbers.
Carlo Trigona A.A. 2007Carlo Trigona A.A. 2007--20082008
ResultsResults µµS GS G
The next figure shows the evolution of the Residence Times DiffeThe next figure shows the evolution of the Residence Times Difference for rence for different volcanic ash quantities (from 0 ml to 3.5 ml) and thedifferent volcanic ash quantities (from 0 ml to 3.5 ml) and the RTD variation. RTD variation.
Variation of RTD as function of volcano Variation of RTD as function of volcano particles quantities particles quantities
Evolution of the Residence Times Evolution of the Residence Times Difference increasing the volcanic ash Difference increasing the volcanic ash
quantities.quantities.
Carlo Trigona A.A. 2007Carlo Trigona A.A. 2007--20082008
ConclusionsConclusions
RTRT--Fluxgate Fluxgate
PrinciplePrinciple
Expressions of RTD and SensitivityExpressions of RTD and Sensitivity
Fluxgate for biomedical applicationsFluxgate for biomedical applications
SetSet--up with PCB FR4up with PCB FR4
SetSet--up with “Wire” coreup with “Wire” core
Fluxgate for volcanic ash detectionFluxgate for volcanic ash detection
SetSet--up with PCB FR4up with PCB FR4
SetSet--up with “Wire” coreup with “Wire” core
µµS GS G
Carlo Trigona A.A. 2007Carlo Trigona A.A. 2007--20082008