Residence Times Difference (RTD) - Fluxgate · PDF fileResidence Times Difference (RTD) -...

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


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


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


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


RTD=RTD= TT++--TT-- Residence Time Residence Time DifferenceDifference

µµS GS GRTDRTD--FluxgateFluxgateBiasBiassignalsignal

Hc

- Hc

+Msat

-Msat

FluxgateFluxgate output output waveformwaveform

Time



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--. .


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



τω

τω

ω

+⎟⎟⎠

⎞⎜⎜⎝

⎛ −=

+⎟⎟⎠

⎞⎜⎜⎝

⎛ +=

⎟⎟⎠

⎞⎜⎜⎝

⎛ −=

e

XC

e

XC

e

XC

H

HHt

H

HHt

H

HHt

ârcsin

1

2ârcsin

1

ârcsin

1

3

2

1

2ârcsin

ârcsin

1

2ârcsin

ârcsin

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

ârcsin

ârcsin

2

ω

⎥⎥⎥⎥⎥

⎦

⎤

⎢⎢⎢⎢⎢

⎣

⎡

⎟⎟⎠

⎞⎜⎜⎝

⎛ −−

+

⎟⎟⎠

⎞⎜⎜⎝

⎛ +−=

∂∂

=22

ˆ1

ˆ/1

ˆ1

ˆ/1

2

e

e

e

e

H

HxHc

H

H

HxHc

H

RTDHx

Sω


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


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


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]


µµS GS GFluxgateFluxgate: PCB FR4 : PCB FR4 technologytechnologyCharacterization

DC Magnetic shield

Solenoid

Fluxgate




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


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


µµS GS GFluxgateFluxgate: “: “wirewire” ” technologytechnologyCharacterization




µµS GS GFluxgateFluxgate: “: “wirewire” ” technologytechnologyCharacterization




MagneticMagnetic particlesparticles: : ImmunoImmuno--assayassay

Detection Detection techniquestechniques

RemanenceRemanence of of magneticmagneticparticlesparticles

RelaxationRelaxation time of time of magneticmagnetic particlesparticles

AntibodyAntibody MagneticMagnetic CoreCore

µµS GS G


MagneticMagnetic particlesparticles: : ImmunoImmuno--assayassay µµS GS G


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


ExperimentalExperimental SetSet--upup (I) (I) µµS GS G


ExperimentalExperimental SetSet--upup (I) (I) µµS GS G


ExperimentalExperimental SetSet--upup (I): (I): circuitcircuit µµS GS G


ResultsResults

Detection of Detection of magneticmagnetic particlesparticles

RTD RTD variationvariation, , functionfunction of of distancedistance and and numbernumber of of particlesparticles

µµS GS G


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


11µµll

NN

NNSS

SS

1µl spot

ExperimentalExperimental SetSet--upup (II) (II)

MagneticMagnetic particlesparticles forfor DNA DNA sequencingsequencing

µµS GS G


ExperimentalExperimental SetSet--upup (II) (II)

Glass support for fluxgate coils

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.



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.


ExperimentalExperimental SetSet--upup (III) (III)

System System forfor volcanovolcano particlesparticles detectiondetection

MagneticMagnetic particlesparticles

µµS GS G


ExperimentalExperimental SetSet--upup (III) (III)

Volcano particles

100 µm core

Primary: 1000 coils 100 µm

Secondary: 1000 coils 100 µm

µµS GS G


ResultsResults

WithWith magneticmagneticparticlesparticles

WithoutWithout magneticmagneticparticlesparticles

µµS GS G


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



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.



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.


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


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