Optical fibers for chemical sensing and biosensing (V. Matejec)

OPTICAL FIBERS FOR CHEMICAL SENSING AND

BIOSENSINGVlastimil Matejec,

Miroslav Chomat, Ivan Kasik, Ondrej Podrazky, Marie Pospisilova

Institute of Photonics and Electronics AS CR, v.v.i., Chaberska 57, 182 51 Prague 8, Czech Republic

Project BIO-OPT-XUV, Workshop W1, Kladno, October 3, 2011

OUTLINE• INTRODUCTION – Performance of IPE• EVANESCENT-WAVE FIBER-OPTIC

SENSORS- Ways for increasing the sensitivity

• FIBER-OPTIC TIPS- Detection in cells and small volumes

• SPECIAL SENSING STRUCTURES- Microstructure fibers, Whispering Gallery Mode (WGM) microresonators

• CONCLUSIONS

INTRODUCTIONInstrumental possibilities of IPE

Technology of optical fibersModified Chemical Vapour Deposition – MCVD

Dip-coating devicesFiber drawing towers

Measurement techniquesAbsorption spectrometers, fluorescence

spectrometer Horiba (Jobin Yvon), AFM, spectral elipsometry available in the

Institute, fiber-optic measurements

TechnologyMCVD

Dip coating

Sol-gelPreparation of preforms for drawing of optical fibers

Fiber DrawingPreform

Graphite furnace

Fiber

Fiber diameterIndicator

Feedback

Spool

Polymerc oating die

Curing furnace

Pulley

Measurement devices

FluorologSpectrometers

Know-howNearly 30 years of expertise at the preparation of

optical fibers 1981-1989: Optical fibers for telecommunications

Polymer-clad silica (PCS) fibersMultimode graded-index (MM GI) fibers

Single mode (SM) fibers1987 - : Special optical fibers for fiber lasers and

amplifiers and sensors

Fiber waveguides

100 μm

PCS

100 μm

Multimode

100 μm

SM

Attenuation of telecommunication fibers

800 1000 1200 1400 1600

1

10

100 10-10

0,01

0,1

0,316

0,794

PCS GI SM

Atte

nuat

ion

[dB

/km

]

Wavelength [nm]

Fully comparable with world producers

Fiber-Optic SensorsFiber-optic hardware for sensors employingEvanescent-wave detection principle

Fiber tipsMicrostructure fibers

Whispering Gallery Mode ResonatorsLong-period gratings in special fibers

Issue:How to control and increase the sensitivity of optical fibers to model chemicals or temperature?

Detected variables change optical properties in the cladding which is detected at the fiber output from changes of the transmitted light.

Evanescent-wave sensors

d

ncl

nco

Guidedwave

Evanescentwave

Radius (r)

Intensity Ez

Radius ( r )

Refractive index n( r )

Core

CladdingDetection site

Advantages- Possibility to control the detection length and access of chemicals into the cladding .

- Detection principles based on refractometry, absorption and fluorescence spectroscopy could be employed

Limitations- Less than 1% of the optical power is transmitted in the cladding in standard fibers → low detection sensitivity.

- Evanescent waves penetrate into the cladding on micrometer distances.

? Ways for improving the detection sensitivity of standard optical fibers

Evanescent-wave sensors

Attenuated Total Reflection – ATR

2

2

2.

2

1 ⎟⎟⎠

⎞⎜⎜⎝

⎛−

⎟⎟⎠

⎞⎜⎜⎝

⎛

−≈

c

c

clcocl

nnd

θθ

θθ

πλεγ

L) exp(- = 0 γii PP

θ= π/2 − Ψ − complementary angle to the angle of reflection Ψ

Higher detection sensitivity ↔ Pi ↓

Ways for increasing the sensitivity standard fibers

- Increase of the detection length L - Increase of bulk absorption coefficient εcl

optochemical transducers pH indicators detection of pH (CO2, NH3 )Ru complexes with the fluorescence quenched by oxygen – detection of O2

Enzymes such as glucoseoxidase – detection of glucose

Ways for increasing the sensitivity- Materials of the core and cladding ncl →nco - PCG

fibers, detection membranes- Decrease of d - sectorial fibers,D-fibers

V. Matejec et al., Sens. Actuators B39 , 334 (1997)- Control of the reflection angle θ → θc

excitation by an inclined collimated beam, beveled fibersA. Abdelghani et al., Sens. Actuators B 44 , 495 (1997)inverted-graded fibersV. Matejec et al. Sens. Actuators B 51, 340 (1998)bent fibers (U fibers), coiled fibers V. Matejec et al., Sensor Lett. B 80, 132 (2001)

Suitable core material

1.36 1.40 1.44 1.48 1.52 1.56 1.60 1.64-4

0

4

8

12

16

20

24

28

PCS PCG-F2 POF

10*lo

g(P/

P 0) [dB

]

Cladding refractive index

Ormocers

Polymer Clad Silica (PCS), Polymer Clad Glass (PCG), Plastic Optical Fibers (POF) – sensitive for different refractive index values

Decrease of the core radius

D-fibers (Culshaw-UK-1985)Sectorial (s-) and D-fibers prepared by pulling from a properly ground and polished circular preform

Used mainly for gas and physical sensorsG. Stewart, W. Jin, B. Culshaw, Sens. Act. B 38, 42-47, 1997

SPR Platforms for Biosensors• D-polished SM fiber

R. Slavik et al., Novel spectral fiber optic sensor based on surface plasmon resonance, Sens. Actuators B74, 106-111 (2001)

Sectorial fibers

Enable to decrease the core dimension a and improve access to evanescent field

Fibers sufficiently robust (due to sectorialpart -0.3 mm)

Core diameter - 30μm (good sensitivity)

Sectorial fibers – Spectral response

~5 times higher response than comparable PCS fibers

Si Detector

Laser diode - 630 nm

α

Motor

Gas in

Detection membrane

Solution in (out)

Cell

Gas out

Fiber

Excitation by an inclined collimated beam

Kinetics measurements, interaction parameters

-24 -18 -12 -6 0 6 12 18 240.0

0.2

0.4

0.6

0.8

1.0

Fixed angle

N2 Toluene (1.9 vol.%) Hexane (12 vol.%)R

elat

ive

outp

ut p

owe

P/P

max

Angle of inclination - α [degree]

MTES membrane

Beveled fibersInstead of excitation by an inclined collimated beam –use of beveled fibers and excitation without the inclination

0 50 100 150 200 250 3000.0

0.3

0.6

0.9

1.2

1.5

1.8

Polymer#2

BEVELED FIBER- sensitivity curves

Beveling 0 o,α50 used

Beveling 36 o, α= 0o

Beweling 18 o, α=0o

10*lo

g[P

(t=0)

/P(e

q.)]

[dB

]

Concentration of toluene [mg/l]

The same sensitivity achieved for beveled fiber and fiber without beveling excited by the inclined beam

Multimode IGI fibersSensitivity control through control of the angle of reflection on core/cladding boundary

GI fiber

IGI fiber

IGI fibers - ray trajectories

Cladding

Cladding

Axial PointLight Source

Core

Ψ2

Ψ1

h

Proper h → the same values of Ψ

Calibration curves of IGI fibers

-0.004 0.000 0.004 0.008 0.012

0

10

20

30

40

IGI fiber

PCS fiber

h=2.0 mm

h=1.2 mm

h =2.0 -1.2 mmFiber endface distance

Out

put s

igna

l [ar

b. u

nit]

Core/cladding refractive-index difference

IGI: tailoring the sensitivity in a RI range 1.41-1.49

Bent fibers - U fibers

Sensitivity to refractive index

1,32 1,34 1,36 1,38 1,40 1,42 1,44 1,460

4

8

12

16

20

24

10 lo

g[P

(dry

)/P]

[dB

]

Refractive index of immersion

R → ∞ R=2 mm R=1 mm

Active length 1 cmλ=670 nm

Sensitivity to absorption coefficientFiber bending - 2 or 1 mm

0 1 2 3 4 5 6 7 80,0

0,1

0,2

0,3

0,4

0,5

0,6

R=2 mm R=1 mm

Straight fiber

10*lo

g[P

(wat

er)/P

] [d

B]

Concentration of methylene blue [mg/l]

pH=5λ=665 nm

Biosensing with U-shaped fibercoated with gold nanoparticles (GNP)

V.V.R. Sai et al., Biosens.Bioelectr. 24, 2804–2809, 2009

Time seconds

a-IgG;b-PBS;c-BSA/PBS;d-PBS;

e-0.06; f-0.6; g-6; h-30 μg/ml

IPE Sensor of oxygen and glucose

LED light

PMT Detector

Main unit Communication A/D,

P

RS

Silica or PMMA

Sensing film is placed

Bent plastic fiber, detection membrane of ORMOCER®(n~1.5) with Ru complex and glucoseoxidase.

Detection based on monitoring oxygen consumption at the enzymatic reaction of glucose

Sensor of oxygen and glucose

0 100 200 300 400 500 600 700 800 900 1000 1100

0.66

0.68

0.70

0.72

0.74

0.76

0.78

0.80buffersolution removed

Air bubbled+1ml 0.1M glucose

+1ml 0.1M glucose

Rel

ativ

e flu

ores

cenc

e in

tens

ity

Time [s]

Time response Calibration

Detection limit 0.2 mM

0.0 0.5 1.0 1.5 2.00.0

0.1

0.2

0.3

0.4

0.5

10*lo

g[P

] [dB

]

Glucose concentration [mM]

Sensors on Fiber-Optic TipsFiber-optic tip= Optical fiber conically narrowed into a sharp tip (micrometer - nanometer scale).

Coupling of higher modes into lower modes –adiabatic tapersSmall tips modified with optochemical transducers suitable for intracelular measurementsE. J. Park et al., J. Mater. Chem. 15 (2005) 2913 – detection of oxygen

50 nm

Sensors on Fiber-Optic Tips

Intracellular measurements.

K-selective taper probes in mouse oocyte (100μm)S.M. Buck et al. , Talanta 63 (2004) 41

Sensors on Fiber-Tapers

- R. Kopelman et al. (USA)E. J. Park et al., J. Mater. Chem. 15 (2005) 2913 – detection of oxygen M.R. Shortreed et al., Sens. Actuators B 38-39 (1997) 8 - detection of potassium

-T. Vo-Dingh et al., (USA)T. Vo-Dingh et al., J. Nanoparticle Research 2 (2000) 17-B.M. Cullum et al., Tibtech September 18 (2000) 388-reviewT. Vo-Dinh et al., Anal Bioanal Chem 382 (2005) 918 -reviewB. M. Cullum et al., Analytical Biochemistry 277 (2000) 25– benzo[a]pyrenetetrol in mammary carcinoma cells

Optical sensorsO.S. Wolfbeis, J. Mater. Chem. 15 (2005) 2657– fluorescence sensing

Near field transmission measurements are used

Approaches of IPE - Reflection

Preparation of TapersInput silica fiber

Elongation of the fiber heated by a burner or a CO2 laser

Heating

Coating with ITO or Al protection coating

Precise cutting

Fiber tapers (IPE)

Tip with a final diameter of 2 μm, coated with a protective ITO layer (mechanical strength)

Detection Layer at Taper TipSilica xerogels embedding BCECF or HPTSHPTS= 8-hydroxypyrene-1,3,6-trisulfonic acid trisodiumsalt (λexc =430 nm, λem = 480 nm) BCECF=2’,7’-Bis(2-carbonylethyl)-5(6)-carboxyfluorescein(Aldrich 14560) (λexc =473 nm, λem = 540 nm)

pH fluorescence indicators used in biochemical measurements

Prepared by contact of the tip end with a sol drop

V Taper

Strong fluorescence signals, easy instrumentation

V-Taper

4 5 6 7 8 9 10

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

Fluorescence signals 620 nm Fit of the data

Rel

ativ

e ou

tput

pow

er

pH

I=0.15 mol⋅l-1 BCECF

Calibration

Excitation 473 nm

Detection of pH in leaf exudates

5.50.16.0

5.60.35.4

5.00.35.4

MeanSt. deviationElectrochem.

Xylem exudateextretedafter cutting off the leaf at its morphological base

Xylem exudateexcreted after cutting off leaf tip

Guttationsolution excreted at the top tip of leaf

pH gradient in leafs has not been detected

Cell Measurements in collaboration with the Institute of Experimental Botany AS CR

Difficult penetration of the cell membrane

Microstructure fiberssensitive to gaseous oxygen

500 μm

Microstructure fibers sensitive to gaseous toluene

1350 1400 1450 1500 1550 1600 1650 1700 1750 18000,0

0,2

0,4

0,6

0,8

1,0

1,2

Atte

nuat

ion

[dB

]

Wavelength [nm]

0,20 mol% 0,27 mol% 0,39 mol% 0,83 mol% N2

On photonics crystal fibers for sensing see e.g.

R.V. Nair, Progress in Quantum Electronics 34, 89–134, 2010M. Skorobogatiy, J. Sensors Volume 2009, Article ID 524237, 20 pages

WGM microresonators

Stems of microspheres fixedin silica capillaries for easily handling

K1-365 μmK2-330 μm

Heating a fiber tip with a burner

K3-67 μm

Heating a fiber with a CO2 laser

Excitation of WGMs - Taper

Top view Side view

Excitation by a red laser -visualisation

Waist diameter < 5μm

μ-Rezonator

WGM resonances-taperMicrosphere K1

Out

putV

olta

ge[m

V]

Time [ms]

---- Microresonator out contact

---- Microresonator in contact

Out of contact

In contact

Q ~ 106 detection length meters

Long Period Gratings Preparation

A high- power CO2 laser

crossing the fiber, induces changes of the mechanical tensions in the fiber – period 0.1-0.5 mm

IPE - LPGs in IGI Fibers

-6 -4 -2 0 2 4 6

1.450

1.451

1.452

1.453

1.454

1.455

1.456

1.457

1.458

1.459

Ref

ract

ive

inde

x

Radius [mm]

9 azimuthal sections

SM fiber core and IGI (GI) cladding enable us to control the LPGs sensitivity to strain and to refractive-index changes

-30 -20 -10 0 10 20 301,455

1,460

1,465

1,470

1,475

1,480

1,485

1,490

Uniformcladding

Graded-indexcladding

Ref

ract

ive

inde

x

Distance from fiber center [μm]

Core

Temperature sensitivity of LPGsSpectral effects

1480 1500 1520 1540 1560 1580

-62

-60

-58

-56

-54

23.9 26.7 30.7 34.5 38.5 43.2

Out

put p

ower

den

sity

(dBm

/nm

)

Wavelength (nm)

Temperature (°C)

Conclusions1) IPE performance for the projectPreparation fiber-optic hardware for chemical sensors and biosensors applicable in medicine.Experience with the application of functional layers onto optical fibersExpertise with characterization of sensing modules 2) IPE offersFiber-optic elements for the application of optochemicaland biological transducers and testing their sensing performance- Bent fibers, beveled fibers, fiber tips, microresonatorsEducation of students

Optical fibers - Group of IPE

THANK YOU

8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt-HPTS

2’,7’-Bis(2-carbonylethyl)-5(6)-carboxyfluoresceinBCECF (Aldrich 14560)

Excitation at 473 nm, reference 430 nm