Multi-Analyte Optical Sensor Chip based on Photo-Patternable Hybrid Sol-Gel Integrated Optics

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Multi-Analyte Optical Sensor Chip based on
Photo-Patternable Hybrid Sol-Gel Integrated Optics

• Jean-Marc Sabattié, Orla McGaughey, Aisling K.
  McEvoy, Jérôme Charmet,
• Brian D. MacCraith

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Outline

• Introduction
• Doped sol-gel materials
• UV-patterned sol-gel waveguides
• Sensing mechanisms
• Deposition process
• Results
• Conclusions / Future work

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Introduction

• Development of a miniaturised multi-analyte
• sensor chip
• Design
• novel configuration for efficient capture of
  fluorescence based on US Patent (US 6137117)
  MacCraith et al.
• Integration of
• planar lightwave circuit technology
  (photo-patternable sol-gel waveguide structure).
• Sol-gel sensor technology
• Detection of O2 and CO2 analytes

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Applications

• Indoor air quality monitoring
• In-car comfort
• Activates air-conditioning when O2 is below or
  CO2 is above a critical level
• In-cabin comfort
• Improve air conditions on flights
• Blood gas analysis

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Chip Design



Blue LED

Luminescent Sensor Spots



(doped sol-gel sensor materials)
Waveguide Series
(UV-patternable sol-gel)

Detector Array
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Sol-Gel Materials

• Doped sol-gel materials
• Tetrathyl orthosilicate (TEOS)
• Methyltriethyl orthosilicate (MTEOS)

inert porous inorganic silica matrix for
sensor immobilisation
Si(OR)4 2 H2O ROH SiO2

• hydrolysis
• condensation

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UV-Patternable Sol-Gel Materials

• UV-patternable sol-gel material
• TEOS
• Zirconium propoxide (ZrOP)
• 3-(methoxysilyl)propyl methacrylate (MPTS)
• Photoinitiator

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UV-Patternable Sol-Gel Materials
Zirconia used for refractive index tuning
Total internal reflection
nair 1 nguiding ncladding
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UV-Patternable Sol-Gel Materials

• to create an organic network cross-linked to the
  inorganic silica/zirconia network by radical
  polymerisation
• non soluble in a wide range of solvents

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UV-Patternable Sol-Gel Materials
Photoinitiator
MPTS
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Photolithography

• Standard Mask-Aligner

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Ridge Waveguides
Picture of ridge waveguides
3D-map of ridge waveguides
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Ridge Waveguides Cross-Sections
Ridge Waveguides
Air
10 mm
Cladding Layer
30 mm
Silicon Substrate
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Oxygen Sensing

• O2 sensor Ru(dpp)3Cl2
• Ruthenium-tris(4,7-diphenyl-1,
  10-phenanthroline) dichloride

l exc 470 nm
l em 610 nm
Fluorescence quenching described by Stern-Volmer
equation
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Carbon Dioxide Sensing

• CO2 sensor HPTS (pH indicator)
• 8-hydroxy-1,3,6-pyrenetrisulfonate salt
• in solution, equilibrium
• acid form ? base form
• production of acid in solution by dissolution of
  CO2
• acidity changes the concentration of the
  conjugate base
• specific excitation of the conjugate base at 470
  nm
• collection of emission at 525 nm

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Multi-Analyte Simultaneous Sensing
Detector Linear Detector Array
Excitation source Single Blue LED
525 nm
610 nm
470 nm
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Sensor Deposition Techniques

• Soft-lithography
• polydimethylsiloxane (PDMS) stamp

• To achieve
• better control of the drop size
• reproducibility

• Pin-printing
• metal pin

• Ink-jet printing
• print-head

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Initial Results - Oxygen
CCD image
200 mm separation between the waveguides
Intensity profile
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Initial Results - Oxygen

• Stern-Volmer plot

• High sensitivity for low concentrations
• 0 -100 detectable range
• Sensitivity tuned by sol-gel formulation

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Conclusions

• Demonstration of an oxygen multi-channel sensor
  chip
• patterning of a series of waveguides
• simultaneous detection of the luminescence
  produced by Ru(dpp)3 in each waveguide

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Future work

• Optimisation of the design parameters
• dimension and refractive index of the waveguides
• Optimisation of the printing method
• to allow for deposition of CO2 and O2 sensor
  spots of specific diameter and thickness
• Demonstration of a miniaturised portable
  multi-analyte sensor with RF communications

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Acknowlegdements

• Orla McGaughey
• Aisling McEvoy
• Jérôme Charmet
• Brian D. MacCraith
• Enterprise Ireland
• Funding under Research Innovation Fund
  IF/2002/353

• Optical Sensors Laboratory,
• National Centre for Sensor Research,
• Dublin City University,
• Ireland