Si based waveguide and surface plasmon sensors

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Transcript Si based waveguide and surface plasmon sensors

Si based Waveguide and Surface Plasmon Sensors

Peter Debackere, Dirk Taillaert, Katrien De Vos, Stijn Scheerlinck, Peter Bienstman, Roel Baets

Photonics Research Group INTEC – IMEC Ghent University

Photonics Research Group http://photonics.intec.ugent.be

Vision Lab-on-Chip Miniaturize and integrate optical sensors

Lab on Chip

Benefits



Compactness allows high integration



Massive parallelisation allows high throughput and multiparameter analysis.



Low fabrication cost can lead to cost effective (even disposable) chips



Biosensors : low fluid volume consumption Challenges



Novel technology, not yet fully developed



Scaling down detection principles



Biosensors: Physical effects: e. g. capillary forces

Silicon-on-Insulator

High Index Contrast Guide and confine light on extremely small scale Sensitivity increases with decreasing waveguide thickness and increasing index contrast Cavities: High Q factors, very small dimensions: Large Free Spectral Range (FSR)

Silicon-on-Insulator

Fabrication using standard CMOS processing steps



Deep UV lithography (248 nm)



Standard Reactive Ion Etching



Very high performance and reproducibility



Easy integration with CMOS and/or microfluidics



Wafer-scale processes



Very high throughput

Silicon-on-Insulator

Simulation : Price per Chip calculated for CMOS research fab wafer mask(2) 300 € 25000 € deep etch Litho Etch Strip 1000 € /lot 1000 € /lot 1000 € /lot shallow etch dicing Litho Etch Strip 1000 € /lot 1000 € /lot 1000 € /lot 100 € /wafer number of chips/wafer (10 mm 2 ) number of wafers/lot 100.000 chips 12500 23 0.402 €/chip

Silicon-on-Insulator

Lab-on-Chip Checklist High integration allowing multiparameter analysis High throughput fabrication, thus low fabrication cost High sensitivity for low fluid volumes Integration with microfluidics High reprocibility

Active Research Community

SOI Lab on a Chip Silicon Photonics Crystal Structures for Sensing PM Fauchet Mach-Zehnder sensing in SiN Lab-on-Chip Platform based on Highly Sensitive Nanophotonic Si Biosensors for Single Nucleotide DNA Testing J Sanchez del Rio Fast, Ultrasensitive Virus Detection using a Young Interferometer Sensor Aurel Ymeti Integrated Surface Plasmon Sensor Low-Index-Contrast SPR Sensor based on combined sensing of Modal, Phase and Amplitude Changes P Levy et al Long-range Surface Plasmon Sensor Long-range Surface Plasmon Waveguides and Devices in Lithium Niobate P Berini

Focus Areas

Biosensors Label-free and multi-parameter detection of biomolecules Refractive index sensing of appropriately functionalized surfaces DNA, mRNA, proteins, sugars, as well as enzymatic activities (proteases, kinase, DNAses) Waveguide sensors, Microring Cavities Surface Plasmon Sensors Strain sensor Measure strain in different in-plane directions , long term , immune from electromagnetic interference

Overview

•

Introduction

•

Biosensors

•

Label-Free Biosensor: Ringresonator



Theory



Measurements: Bulk sensing



Measurements: Surface sensing

•

Label-Free Biosensor: Surface Plasmon Interferometer



Theory



Simulation: Intensity Measurement Mode



Simulation: Wavelength Interrogation Mode



Measurements

•

Strain Sensor

•

Conclusions

Biosensors

Waveguide sensors :Microring Cavities

•

Evanescent field sensing

•

Technology and principle well understood

•

Surface modification and biomolecule immobilisation are the biggest issues Surface Plasmon Sensor

•

Sensing with surface plasmon modes

•

Novel technology and principle

•

Surface modification and biomolecule immobilisation well understood

Overview

•

Introduction

•

Biosensors

•

Label-Free Biosensor: Ringresonator



Theory



Measurements: Bulk sensing



Measurements: Surface sensing

•

Label-Free Biosensor: Surface Plasmon Interferometer



Theory



Simulation: Intensity Measurement Mode



Simulation: Wavelength Interrogation Mode



Measurements

•

Strain Sensor

•

Conclusions

Theory

Incoupling Port Drop Port Pass port



resonance



n eff



D m

microring cavity biosensor flow with biomolecules matching biomolecule (analyte) biorecognition element (ligand) functional monolayer © intec 2007 - Photonics Research Group - http://photonics.intec.ugent.be

Theory

Intensity Measurement Mode

•

Monochromatic Input, monitor output power as a function of refractive index

•

Advantage : real-time interaction registration

•

Disadvantage : limited range Wavelength Interrogation Mode

•

Broadband input, monitor resonance wavelength as a function of refractive index

•

Advantage: easy to multiplex

•

Disadvantage: slower detection method



Sensitivity

Increases with increasing Q factor of the ring

 

resonance

  3

  

Measurement Setup

Light from tunable laser Light to photodetector Flow Cell SiO 2 Si Temperaturecontrol Results presented here: Static measurements :

zero flow rate

Flow cell dimensions

Ø~2mm 2

Towards microfluidic setup:

Continuous flow

with syringe pump Flow cell dimensions

Ø~100μm 2

0.35

0.3

0.25

0.2

0.15

0.1

0.05

0 1.333

Bulk refractive index sensing

• No surface chemistry involved • Different salt concentrations • Good repeatability (small variations around mean value) 1.334

1.335

1.336

1.337

1.338

refractive index [RIU]

Sensitivity

• • • shift of 70nm/RIU ∆λmin= 5pm

∆n min =1*10 -5 RIU

Surface Chemistry

1. Cleaning and oxidation 2. Silanization: surfaces are dip-coated in APTES solution 3. Coupling of Biotin-LC-NHS © intec 2007 - Photonics Research Group - http://photonics.intec.ugent.be

Surface Sensing Biotin/Avidin

biotin buffer pH7,4 0.0045

resonator avidin concentration resonator buffer pH7,4 resonator 0.004

0.0035

0.003

0.0025

0.002

0.0015

0.001

∆P 0.0005

∆λ 0 1551.80

1551.90

1552.00

1552.10

1552.20

1552.30

w avelength [nm]

1552.40

1552.50

1552.60

avidin biotin

Surface Sensing Biotin/Avidin

• • • 0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0 0 5 10 15 20 25 avidin concentration [μg/ml] High avidin concentrations: saturation Low avidin concentrations: quantitative measurements ∆λ min = 5pm 

50ng/ml

Overview

•

Introduction

•

Label-Free Biosensor: Ringresonator



Theory



Measurements: Bulk sensing



Measurements: Surface sensing

•

Label-Free Biosensor: Surface Plasmon Interferometer



Theory



Simulation: Intensity Measurement Mode



Simulation: Wavelength Interrogation Mode



Measurements

•

Strain Sensor

•

Conclusions

Prism

Theory: Surface Plasmons

•

Evanescent TM polarized electromagnetic waves bound to the surface of a metal

•

Benefits for Biosensing



High fields near the interface are very sensitive to refractive index changes



Gold is very suitable for biochemistry From source To detector R Gold



Theory

Bulky surface plasmon biosensor Fully integrated lab-on-chip solution in Silicon-on-Insulator

Theory : Concept

Surface Plasmon Interferometer

Sample medium

10 μm © intec 2007 - Photonics Research Group - http://photonics.intec.ugent.be

Si SiO 2 Si

Simulation : Intensity Measurement

Constructive Interference

Simulation : Intensity Measurement

Destructive Interference

Simulation : Intensity Measurement

Optimalisation of Design

Si thickness = 160 nm Length = 10  m Si thickness = 100 nm Length = 6.055  m © intec 2007 - Photonics Research Group - http://photonics.intec.ugent.be

Simulation : Intensity Measurement

Sensitivity Analysis

10 10 -5 -6 10 -7

Sensitivity

Change in the refractive index that causes a drop or rise in the transmission of 0.01 dB

Simulation : Intensity Measurement

Sensitivity Analysis

10 -5 10 -6 10 -7

Comparison

Prism Coupled SPR 1 x 10-6 Grating Coupled SPR 5 x 10-5 MZI SOI Sensors 7 x 10-6 Integrated SPR LIC 5 x 10-6

BUT Dimensions are two orders of magnitude smaller

Simulation: Wavelength Interrogation

Shift of the spectral minimum

Shift of the spectral minimum as a function of the bulk refractive index © intec 2007 - Photonics Research Group - http://photonics.intec.ugent.be

Simulation: Wavelength Interrogation

Sensitivity to adlayers

For n=1.34 adlayer

6 pm/nm

Measurement Setup Side View Top View

-30 -32 -28 -26 -22 -24 -18 -20 -161530

Transmission as a function of wavelength Measurement

1540

Measurement Results

1550 1560 1570 1580 1590

5 μm Au O2 toplayer

1600 1610

Compared to Theory

•

Qualitative Agreement between experiment and theory

•

Quantitative Need for a better fabrication process

-11 1480

Transmission as a function of wavelength Simulation

1500 1520 1540 1560 1580 1600 -12 -13 -14 -15 -16 -17 -18

Wavelength [nm] Wavelength (nm)

Overview

•

Introduction

•

Label-Free Biosensor: Ringresonator



Theory



Measurements: Bulk sensing



Measurements: Surface sensing

•

Label-Free Biosensor: Surface Plasmon Interferometer



Theory



Sensitivity



Fabrication



Measurements

•

Strain Sensor

•

Conclusions

Strain sensor

Introduction : Electrical resistance gage



Most popular strain gage



Moderate long term reliability



No absolute measurements



2-D strain sensing



Small resistance changes Fiber Bragg Gratings (FBG)



More expensive



Good long term reliability



‘Absolute measurements’



Only 1-D strain sensing



EMI insensitive

Strain sensor

Try to combine some advantages of electrical resistance gages and FBGs

  

Strain



L/L typical



R = 0.2

= 1000

e

typical



= 1000 pm ~

= 1000

e

electrical : resistance, SOI ring or racetrack resonator

 

Resonance wavelength depends on strain

    

L L

 

n eff n eff

Wavelength measurement = robust



Wavelength demultiplexing (large FSR needed) optical : wavelength

Strain sensor

Structure of SOI strain sensor Layer stack SiO2 Si SiO2 2µm polyimide 10µm Circuit layout

Strain sensor



Thin foil strain sensor is bonded to Al plate for testing



Bending test : bending the plate results in tensile strain at top surface



Not yet fiber packaged



Photo of measurement setup Sensor circuit

Strain sensor

Experimental results : wavelength shift vs beam deflection, good agreement with theoretical predictions

0.9

2 0.8

0.7

1 3 0.6

0.5

4 0.4

0.3

0.2

0.1

0 0 1 2 3 4

beam deflection (mm)

5 6 7

Uni-axial strain

Strain sensor

Experimental results :

 

Circular resonator :



=0.85

xx (pm/

e

) Racetrack resonator

: 

=0.99

xx ,



=0.63



Sensitivity and cross-sensitivity can be improved by optimized design

 

=1.3

xx ,



=0.3

yy (pm/

e

)

Overview

•

Introduction

•

Label-Free Biosensor: Ringresonator



Theory



Measurements: Bulk sensing



Measurements: Surface sensing

•

Label-Free Biosensor: Surface Plasmon Interferometer



Theory



Sensitivity



Fabrication



Measurements

•

Strain Sensor

•

Conclusions

Conclusions

Theory & Proof of Bulk Design Principle Sensing Surface Chem Adlayer sensing Optimize Multi para 10 -5 RIU P: 10ng/ml



: 50ng/ml



We have demonstrated new type of optical strain sensor



Thin foil SOI strain gage



Sensitivity comparable to Fiber Bragg Gratings, but can measure strain in different in-plane directions

Acknowledgements

GOA Biosensor Project IAP Photon IWT Vlaanderen FWO Vlaanderen FOS&S

Photonics Research Group

Alternative (extended) Conclusions

http://photonics.intec.ugent.be

Conclusions

Silicon on Insulator Microring Cavities



SOI microrings



Extremely small high Q cavities



Fabrication with standard CMOS processing techniques



Characterization



∆n ~ 10-4 for bulk refractive index sensing



LOD 10ng/ml avidin concentration

Conclusions

Silicon-on-Insulator Surface Plasmon Sensors

•

Theoretical



Surface Plasmon Biosensor based on new concept



Sensitivity comparable with current integrated SPR devices



Design is very versatile



Two orders of magnitude smaller than current integrated SPR devices

•

Experimental



Proof-of-Principle



Discrepancy between theoretical predictions and experimental values

Conclusions

Silicon-on-Insulator Strain Sensors



We have demonstrated new type of optical strain sensor



Thin foil SOI strain gage



Sensitivity comparable to Fiber Bragg Gratings, but can measure strain in different in-plane directions

Photonics Research Group

APPENDIX

http://photonics.intec.ugent.be

Simulation: Wavelength Interrogation

H 2 O Si SiO 2 Si

Novel Concept

Coupling to SP modes

Novel Concept

Mode dispersion gold-clad waveguide

Waveguide mode cutoff

SPR History

Integrated Surface Plasmon Resonance Device Thin metallic layers

H 2 2 O

Supermodes integration

•

Design limited to low-index contrast due to phase matching considerations Asymmetric cladding Interface Modes

• • •

Intensity Measurement/ Simulation

Parameters

Length of the sensing region Thickness of the Si waveguide Thickness of the Au layer

Limitations

•

Position of the minima : Dip in the transmission curve @ 1.550 micron should be near n = 1.33

•

Maximum Visibility : Loss along both ‘arms’ has to be equal

Sensitivity Analysis

Sensitivity to adlayers

For n=1.34 adlayer

Si based waveguide and surface plasmon sensors

Transcript Si based waveguide and surface plasmon sensors

Si based Waveguide and Surface Plasmon Sensors

Vision Lab-on-Chip Miniaturize and integrate optical sensors

Lab on Chip

Silicon-on-Insulator

Silicon-on-Insulator

Silicon-on-Insulator

Silicon-on-Insulator

Active Research Community

Focus Areas

Overview

Biosensors

Overview

Theory

Theory

Measurement Setup

Bulk refractive index sensing

Surface Chemistry

Surface Sensing Biotin/Avidin

Surface Sensing Biotin/Avidin

Overview

Theory: Surface Plasmons

Theory

Theory : Concept

Simulation : Intensity Measurement

Constructive Interference

Simulation : Intensity Measurement

Destructive Interference

Simulation : Intensity Measurement

Optimalisation of Design

Simulation : Intensity Measurement

Sensitivity Analysis

Sensitivity

Simulation : Intensity Measurement

Sensitivity Analysis

Comparison

Simulation: Wavelength Interrogation

Shift of the spectral minimum

Simulation: Wavelength Interrogation

Sensitivity to adlayers

6 pm/nm

Measurement Setup Side View Top View

Measurement Results

Overview

Strain sensor

Strain sensor

Strain sensor

Strain sensor

Strain sensor

Strain sensor

Overview

Conclusions

Acknowledgements

Alternative (extended) Conclusions

Conclusions

Conclusions

Conclusions

APPENDIX

Simulation: Wavelength Interrogation

Novel Concept

Coupling to SP modes

Novel Concept

Mode dispersion gold-clad waveguide

SPR History

Intensity Measurement/ Simulation

Parameters

Limitations

Sensitivity Analysis

Sensitivity to adlayers

6 pm/nm

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