Interferometric optical fiber biosensor.ppt

Optical BiosensorOptical BiosensorProf. Xingwei WangProf. Xingwei Wang

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Summary of last week: Evanescent wave

Fiber probe design

Light

• Transverse electromagnetic wave• Reflection• Refraction• Diffraction• Interference

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Interferometer• Interference usually refers to the interaction of

waves that are correlated or coherent with each other– either because they come from the same source – or because they have the same or nearly the same

frequency.

• Two waves that coincide with the same phase will add to each other.

• Two waves that have opposite phases will cancel each other out, assuming both have the same amplitude.

5http://en.wikipedia.org/wiki/Interferometer

Constructive and destructive interference

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http://en.wikipedia.org/wiki/Interference

Constructive and destructive interference

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http://en.wikipedia.org/wiki/Interference

Constructive and destructive condition

• If these two paths differ by a whole number (including 0) of wavelengths, there is constructive interference and a strong signal at the detector.

• If they differ by a whole number and a half wavelengths (e.g., 0.5, 1.5, 2.5 ...) there is destructive interference and a weak signal.

• Violate conservation of energy?

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Constructive and destructive condition

• If these two paths differ by a whole number (including 0) of wavelengths, there is constructive interference and a strong signal at the detector.

• If they differ by a whole number and a half wavelengths (e.g., 0.5, 1.5, 2.5 ...) there is destructive interference and a weak signal.

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Young's Double Slide Experiment

• http://www.youtube.com/watch?v=9UkkKM1IkKg

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Constructive and destructive condition

• If these two paths differ by a whole number (including 0) of wavelengths, there is constructive interference and a strong signal at the detector.

• If they differ by a whole number and a half wavelengths (e.g., 0.5, 1.5, 2.5 ...) there is destructive interference and a weak signal.

• Violate conservation of energy?

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Video

• http://www.youtube.com/watch?v=RRi4dv9KgCg (Optics: Destructive interference -Where does the light go?)

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Michelson interferometer

13http://en.wikipedia.org/wiki/Interferometer

Michelson interferometer

• http://www.youtube.com/watch?v=j-u3IEgcTiQ

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Mach-Zehnder interferometer

15http://en.wikipedia.org/wiki/Interferometer

How does it work?

• A slight tilt of one of the beam splitters will result in a path difference and a change in the interference pattern.

• Can be very difficult to align.• Very sensitive.

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Advantages: very sensitive

• Coherent interferometry uses a coherent light source (for example, a helium-neon laser), and can make interference with large difference between the interferometer path length delays.

• The interference is capable of very accurate (nanometer) measurement by recovering the phase.

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Advantages & Problem1

• Advantage: Very sensitive• Problem:

– Coherent interferometry suffers from a 2π ambiguity problem

– If between any two measurements the interferometric phase jumps by more than 2π the phase measurement is incorrect

– Dynamic range

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Advantages & Problem1

• Advantage: Very sensitive• Problem:

– Coherent interferometry suffers from a 2π ambiguity problem

– If between any two measurements the interferometric phase jumps by more than 2π the phase measurement is incorrect

– Dynamic range

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Solution

• Combining interferometry results obtained using multiple wavelengths of illumination

• Ambiguity interval can be extended to indefinitely large dynamic ranges of measurement

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Problem 2:

• Long (typically 9–20 mm) evanescent-wave/biomaterial interaction paths

• Required length for a detectable cumulative effect when using a single pass of light through the sensing arm

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Problem 2:

• Long (typically 9–20 mm) evanescent-wave/biomaterial interaction paths

• Required length for a detectable cumulative effect when using a single pass of light through the sensing arm

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Fabry-Perot interferometer

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EFPI

• The required sensing length may be reduced by having the light double back through multiple reflections along its propagation path.

• The use of a single-cavity extrinsic Fabry–Pérot interferometer (EFPI) as a guided-wave/bulk-biomaterial interaction biosensor.

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J. L. Elster, M. E. Jones, M. K. Evans, S. M. Lenahan, C. A. Boyce, W. Velander, and R. VanTassell, “Optical fiber extrinsic Fabry–Pérot interferometric (EFPI)-based biosensors,” SPIE, vol. 3911, pp. 105–112,2000.

Fabry Perot Interferometer

• http://www.youtube.com/watch?v=BT675FhuvuA

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Schematic diagram of a PSW-FPI integrated in a uMZ

structure

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Schematic view of experiment setup

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Huygen's principle

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Diffraction

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Comparable in size to the wavelengthLight spreads around the edges of the obstacle

Single slit diffraction

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Analysis

• Huygen's principle– Each part of the slit can be thought of as an

emitter of waves. – All these waves interfere to produce the

diffraction pattern.

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Results

• Destructive interference: 1-5; 2-6; 3-7; 4-8…• Half a wavelength out of phase

– (w/2)sinθ = λ/2 or wsinθ = λ• Other dark fringes in the diffraction pattern produced

are found at angles θ for which– wsinθ = mλ

• If the interference pattern is viewed on a screen a distance L from the slits, then the wavelength can be found from the spacing of the fringes. – λ = zw/(mL)

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Results

• Destructive interference: 1-5; 2-6; 3-7; 4-8…• Half a wavelength out of phase

– (w/2)sinθ = λ/2 or wsinθ = λ• Other dark fringes in the diffraction pattern produced

are found at angles θ for which– wsinθ = mλ

• If the interference pattern is viewed on a screen a distance L from the slits, then the wavelength can be found from the spacing of the fringes. – λ = zw/(mL)

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Diffraction and Interference

• http://www.youtube.com/watch?v=1FwM1oF5e6o

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Double Slit Diffraction

• http://www.youtube.com/watch?v=iZdWQKaykvs

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Exercise 1

• When a monochromatic light source shines through a 0.2mm wide slit onto a screen 3.5m away, the first dark band in the pattern appears 9.1mm from the center of the bright band. What is the wavelength of the light?

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Solution 1

• Z=9.1mm; L=3.5m; w=0.2mm• Lamda=zw/(mL)=520nm

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Exercise 2

• The first order bright line appears 0.25cm from the center bright line when a double slit grating is used. The distance between the slits is 0.5mm and the screen is 2.7m from the grating. Find the wavelength.

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Solution 2

• Z=0.25cm• L=2.7m• W=0.5mm• lamda=zw/(mL)=463nm

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Exercise 3

• A diffraction grating has 420 lines per mm. The grating is used to observe light with a wavelength of 440nm. The grating is placed 1.3m from the source. Where will the first order bright line appear?

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Solution 3

• Lamda=wsinө• w=1/420=2.38um• Lamda=440nm• L=1.3m• Z=Ltanө~ 24.5cm

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Diffraction grating

• Identical, equally-space slits?• The bright fringes, which come from

constructive interference of the light waves from different slits, are found at the same angles they are found if there are only two slits.

• But the pattern is much sharper.• Why?

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Diffraction grating

• Each scattering center acts as a point source of spherical wavefronts;

• These wavefronts undergo constructive interference to form a number of diffracted beams.

• Many positions of completely destructive interference between the bright, constructive-interference fringes.

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Diffraction Grating

• http://www.youtube.com/watch?v=_2sGoDiTrC8

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Colorimetric resonant reflection as a direct

biochemical assay technique• A guided mode resonance filter that, • when illuminated with white light, • is designed to reflect only a narrow band

of wavelengths• where the reflected wavelength is tuned by

the adsorption of biological material onto the sensor surface.

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Label-free

• Common labels– radioisotopes, fluorophores, enzyme substrates.

• Label-free– removes experimental uncertainty induced by the effect of

• the label on molecular conformation, • blocking of active binding epitopes, • steric hindrance,• inaccessibility of the labeling site, • or the inability to find an appropriate label that functions

equivalently for all molecules in an experiment.– Label-free detection methods greatly simplify the time and

effort required for assay development, • Removing experimental artifacts from quenching, shelf life,

and background fluorescence.

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Key technology - grating

• A narrow bandwidth guided mode resonant filter structure – a sub-wavelength grating structure – produces a particular diffraction anomaly providing a surface

that, – when illuminated with white light at normal incidence, – reflects only a very narrow (resonant) band of wavelengths.

• The resonantly reflected wavelength is shifted by the attachment of biomolecules to the guided mode filter, – small changes in surface optical density can be quantified

• Equivalent sensor structures have been fabricated onto glass substrates and incorporated into sheets of plastic film.

• Incorporation of the sensor into large area disposable assay formats such as microtiter plates and microarray slides.

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Sensitivity

• Protein-protein• Detection of antibody with 8.3 nM

sensitivity• Low non-specific binding

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Schematic diagram

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Reflectivity response

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Computer simulation of spectral shift due to the

binding of molecules

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Computer simulation results

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Reading system

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Schematic diagram of the array

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SEM picture of the grating

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Reading system

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Measured shifting of the resonant wavelength with

binding of molecules

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Peak wavelength shift

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Test

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Imaging

• To produce images of bound biomolecule patterns as applied by a microarray spotter

• An instrument is used to acquire spatial maps of the resonant reflected wavelength

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Applications

• The biosensor imaging capability is expected to yield applications in pharmaceutical compound screening, genomics, proteomics, and molecular diagnostics,

• where there is a need to screen large numbers of biochemical interactions against samples

• using low volumes of reagents.61

Parallel detection with an array

• The ability to detect the interactions between sets of DNA probes arrayed on to glass surfaces and test samples are used for genotyping, gene expression analysis, and gene sequencing.

• Likewise, arrays of hybridized protein probes are finding applications in protein pathway analysis, and protein expression diagnostic tests.

• The concept of parallel detection of sample interaction with an array of hybridized probes is further expanding into

• Small molecule screening for pharmaceutical discovery• Environmental testing, and others.

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Schematic diagram for imaging

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VCSEL laser and PIN detectors

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System setup

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Dynamic measurements

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Static measurements

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Comparison results with white light and laser

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Advantages

• Low cost• Multi-analyte analysis in parallel• Simple setup – no coupling prisms• No electricity wiring

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Video

• http://www.owls-sensors.com/label-free-biosensor (OWLS)

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References

• Optical fiber extrinsic Fabry–Pérot interferometric (EFPI)-based biosensors J. L. Elster, M. E. Jones, M. K. Evans, S. M. Lenahan, C. A. Boyce, W. Velander, and R. VanTassellSPIE, vol. 3911, pp. 105–112,2000.

• Investigation of a Periodically Segmented Waveguide Fabry–PÉrot Interferometer for Use as a Chemical/Biosensor N Kinrot, M NathanJournal of Lightwave Technology, Volume 24, Number 5 (May 2006) Page Numbers: 2139 - 2145

• Label-free optical technique for detecting small molecule interactionsBo Lin, Jean Qiu, John Gerstenmeier, Peter Li, Homer Pien, Jane Pepper and Brian Cunningham Biosensors and Bioelectronics, Volume 17, Issue 9, September 2002, Pages 827-834

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References

• A new method for label-free imaging of biomolecular interactionsLi, P.Y.; Bo Lin; Gerstenmaier, J.; Cunningham, B.T.;Sensors, 2003. Proceedings of IEEEVolume 1, 22-24 Oct. 2003 Page(s):310 - 315 Vol.1 Digital Object Identifier 10.1109/ICSENS.2003.1278948

• A plastic colorimetric resonant optical biosensor for multiparallel detection of label-free biochemical interactionsCunningham, B.; Qiu, J.; Lin, B.; Li, P.; Pepper, J.;Sensors, 2002. Proceedings of IEEEVolume 1, 12-14 June 2002 Page(s):212 - 216 vol.1 Digital Object Identifier 10.1109/ICSENS.2002.1037084

• Colorimetric resonant reflection as a direct biochemical assay techniqueBrian Cunningham, Peter Li, Bo Lin and Jane Pepper

Sensors and Actuators B: Chemical, Volume 81, Issues 2-3, 5 January 2002, Pages 316-328

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Multimode Fiber

• http://www.youtube.com/watch?v=6xYOzY4zj0o

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Mode Power Distribution in Multimode Fibers

• http://www.youtube.com/watch?v=gBbiFPaPsRk (0” – 2’36”)

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