WO2008075289A1 - Sub wavelength aperture - Google Patents
Sub wavelength aperture Download PDFInfo
- Publication number
- WO2008075289A1 WO2008075289A1 PCT/IB2007/055208 IB2007055208W WO2008075289A1 WO 2008075289 A1 WO2008075289 A1 WO 2008075289A1 IB 2007055208 W IB2007055208 W IB 2007055208W WO 2008075289 A1 WO2008075289 A1 WO 2008075289A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- radiation
- aperture
- luminophore
- detection volume
- excitation
- Prior art date
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
- G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
- G01N21/64—Fluorescence; Phosphorescence
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
- G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
- G01N21/64—Fluorescence; Phosphorescence
- G01N21/6445—Measuring fluorescence polarisation
Definitions
- the invention relates to the field of detecting a presence of a luminophore in a detection volume.
- US2005244863 discloses a configuration for excitation of luminophores by means of an evanescent wave.
- An evanescent wave is a rapidly decaying electromagnetic field which cannot propagate due to a sub-wavelength aperture.
- exciting radiation is provided to penetrate as an evanescent wave in a bio-molecule containing mixture.
- the evanescent wave is created by a structure having sub wavelength apertures.
- the apertures only allow a small portion of the generated radiation to be transmitted. This causes a limited yield of luminescent light to be used for detection purposes.
- a method of detecting a presence of a luminophore in a detection volume comprising: providing excitation radiation in said detection volume; providing a luminophore in a medium in said detection volume, the luminophore being excitable by said excitation radiation to emit luminescent radiation; and detecting at least a polarization component of said luminescent radiation through an aperture of said detection volume by a detector, said aperture having a smallest in plane dimension; wherein said luminophore is selected to emit luminescent radiation in said medium having a wavelength in said medium that is larger than twice said smallest dimension; and wherein said luminophore is selected to be excitable by excitation radiation having a wavelength in said medium that is smaller than twice said smallest dimension.
- an apparatus for detecting a presence of a luminophore in a detection volume comprising: a detection volume; the detection volume comprising an aperture having a smallest in plane dimension and arranged to comprise said luminophore in a medium; a radiation source for providing excitation radiation in said detection volume, the lumiophore being excitable by said excitation radiation to emit luminescent radiation; and a detector arranged and constructed to detect at least a polarization component of said luminescent radiation said detector is selected to detect luminescent radiation having a wavelength in said medium that is larger than twice said smallest dimension; and wherein said radiation source is selected to provide excitation radiation having a wavelength in said medium that is smaller than twice said smallest dimension.
- the aperture defines an in plane interface where a luminophore can be excited.
- the detection volume can be limited, by detecting fluorescence light that is created on the interface of the aperture. Accordingly, the excitation efficiency can be improved; while keeping the detection volume limited.
- Fig.l illustrates a basic embodiment according to an aspect of the invention
- Fig.2 illustrates a combined effect of excitation and fluorescence detection efficiency
- Fig.3 illustrates a transmissive detection of luminescent radiation according to an aspect of the invention
- Fig.4 illustrates an alternative embodiment according to an aspect of the invention using slits
- Fig.5 illustrates a schematic graph showing a detection efficiency for the embodiment illustrated in Fig.4.
- aperture biosensors are used for detecting luminophores, such as fluorophores, to identify specific types of bio-molecules that are being investigated.
- these apertures use a pin-hole or slit concept to allow exitation light as evanescent radiation into a detection volume.
- the combined effect of the excitation and fluorescence detection efficiency significantly reduces the total efficiency of the biosensor.
- a secondary problem is that in the particular case of a pinhole biosensor in transmission mode the total efficiency is the same over the entire dept of the biosensor. Preferably, the total efficiency is higher in certain parts, because that effectively will give a smaller excitation/detection volume.
- the invention proposes a sub-wavelength aperture to limit only the detection volume.
- luminophores with a very large wavelength difference (stokes shift) between excitation and fluorescence in combination with a aperture (bio)sensor.
- excitation light can enter substantially unhindered through the aperture 1 of the detection volume, significantly increasing the effectiveness of the excitation.
- Said luminophore is selected to emit luminescent radiation having a wavelength so that the luminescent radiation generates an evanescent field inside the aperture. Accordingly, luminescent radiation is blocked from escaping the aperture 1 except for the portion present on an interface 20 of the aperture 1 so that the detection volume 101 is kept small to reduce the effect of background fluorescence and thus increase the selectivity of the detection by improving the signal-to-noise ratio of the biosensor.
- a slit can be used instead of a hole.
- the advantage of using a slit is that the suppression becomes polarization dependant, and due to this 50% of the generated fluorescence can exit the slit without being suppressed.
- a smallest dimension of the aperture is selected to be larger than one half of the excitation light wavelength in said medium; and smaller than one half of the wavelenght in said medium of the luminescent light emitted by a luminophore to be excited by the excitation light.
- the type of luminophore that is used is selected to be excitable by radiation having a wavelength in said medium substantially smaller than twice the smallest aperture dimension; while emitting luminescent light substantially larger than the twice the smallest aperture dimension, so that luminescent radiation is trapped within the aperture except for the luminescence that is created substantially on the interface 20 of the aperture.
- the interface 20 is formed by an outer plane defined by the aperture 1 , when seen in a traveling direction of the fluorescent light 4.
- the current invention proposes the use of luminophores that have (very) large wavelength difference (stokes shift) between excitation and fluorescence.
- luminophores such as quantum dots (ref. "Quantum Dots Lend Simplicity", B. D. Butkus, Biophotonics International, pp. 34-40, May 2004).
- quantum dots ref. "Quantum Dots Lend Simplicity", B. D. Butkus, Biophotonics International, pp. 34-40, May 2004.
- quantum dots may be illuminated with a wavelength of 330 nm and it may give emission fluorescence at 610 nm.
- this emission fluorescence can also be varied, to allow multiplexing with different fluorescence emission wavelengths (for example, excitation at 330 nm and emission at 510, 555, 590 and 610 nm, allowing 4 analytes to be measured simultaneously).
- fluorescence emission wavelengths for example, excitation at 330 nm and emission at 510, 555, 590 and 610 nm, allowing 4 analytes to be measured simultaneously.
- Another example of luminophores with a large Stokes shift are LaF3:Nd nanoparticles. These nanoparticles are composed of Lanthanum Fluoride (LaF3) crystals with about 5 % of the Lanthanum ions (La3+) replaced by Neodymium ions (Nd3+). These nanoparticles have typical diameters of 6 nm and prevent quenching of the excited states.
- LaF3 Lanthanum Fluoride
- Nd3+ Neodymium ions
- Each nanoparticle consists of 60 Neodymium ions, 1200 Lanthanum ions and 3780 Fluoride ions (F-). Pumping at a wavelength around 575 nm results in emission around wavelengths of 880nm, 1050 nm, and 1330nm.
- a basic embodiment according to the invention is outlined, showing an aperture 1 within a material 2.
- the aperture 1 defines a width 102 as a smallest in plane dimension, of an interface plane 20 normal to the paper defining a lower side of detection volume 101.
- Detection volume 101 is further bounded by the aperture width 102.
- the size of the aperture 1 is large enough to allow excitation radiation 3 to travel through the aperture essentially without being suppressed.
- the luminophore 5 is selected to be excitable by excitation radiation 3 having a wavelength in said medium that is smaller than twice said aperture width 102.
- fluorescence 4 generated by fluorophores 5 and 6 is being suppressed, because the fluorescence wavelength is substantially larger than the aperture width 102.
- the detection volume 101 is limited, at least for fluorescence 4 that is polarized in a direction transverse to the width 102 of the aperture. Fluorescence 4 generated by a fluorophore 5 located near the interface 20 (independent of polarization) can leave the aperture 1 and reach a detector (not shown). Fluorescence 4 generated further into the aperture 1 , for example by fluorophore 6 is suppressed before it can reach the exit of aperture 1 since the fluorophore 6 is selected to emit luminescent radiation in having a wavelength in said medium that is larger than twice said smallest dimension.
- the signal fluorophores may be bound to capture probes within the detection volume 101, such that fluorophores 6 are background particles, while the fluorophore 5 is a signal particle.
- a filter may be provided (not shown) that blocks the excitation and transmits the fluorescence radiation 4, so that the excitation radiation 3 can be prevented from being detected by a detector.
- the width 102 of the smallest dimension of the aperture 1 is such that: excitation light 3 is able to travel through the aperture 1 without being (substantially) suppressed; - fluorescence light 4 is substantially suppressed, at least in a dimension defined by the aperture width 102 when traveling through the aperture 1.
- the excitation wavelength is 575nm and the generated fluorescence is at 880nm; having the aperture filled with water having an index of refraction of 1.3.
- Using an aperture with a smallest dimension of 250nm and an aperture depth of depth of 400nm calculation can show that this will result in a transmission of the excitation light of about 84.4% and a transmission of the fluorescence of about 0.7% when traveling through the entire aperture.
- Fig.2 shows the combined effect of excitation and fluorescence detection efficiency, for a configuration typically as in Fig.l; that is, with excitation light traveling into the aperture 1.
- the x-axis shows in arbitrary units a depth parameter of the aperture 1, wherein the efficiency of the excitation radiation 3 is shown to be generally unhindered while traveling through the aperture 1 , giving a minor decrease in excitation efficiency with distance; the typical efficiency lowering from 1 to 0.8.
- the fluorescence 4 having a wavelength typically larger than the aperture 1 is accordingly strongly suppressed by the aperture 1 , and therefore the detection efficiency increases near the exit of the aperture. It is noted that in this case the aperture is used in transmission mode. When combined, the total efficiency is still high, limited only substantially by the fluorescence detection efficiency.
- a small detection volume is provided which is formed by substantially a volume between the aperture just before the exit of the aperture, and accordingly only comprises a limited number of luminophores.
- the excitation/detection volume is limited by the detection volume the since only fluorescence 4 near the exit can leave the aperture 1.
- Fig.3 show an embodiment wherein a substrate 7, such as a glass plate, is positioned at the interface 20 of the aperture 1. Accordingly, a top layer of the glass plate 7 forms interface 20, that prevents the fluorophores 5, 6 from being present in an in between volume between a detection volume 101 and detector 10.
- excitation radiation 3 in an in between volume between the detection volume 101 and the detector 10 cannot contribute to excitation of fluorophores since, no fluorophores are present between the detector and the interface 20 of the aperture (on detector side). In this way inadverted illumination of fluorophores by the excitation beam which would contribute to a background fluorescence signal is prevented.
- a glass plate 7 is used as substrate for the apertures (instead of the embodiment shown in Fig.5 that has no substrate beneath the apertures).
- This is shown in Fig.3, which shows a substrate 7 beneath the aperture.
- the figure also shows a lens 8 that is used to focus the fluorescence onto a detector 10.
- a detection filter 9 is used to block the remaining excitation radiation.
- An additional advantage of the substrate 7 is that fluorophores can bind to the glass surface within the aperture, positioning the fluorophores in the location with the highest total efficiency of excitation+detection.
- the aperture 1 may be used in reflection mode.
- the combined efficiency of excitation and detection is similar to the transmission mode embodiment that was discussed with reference to Fig.2.
- the excitation beam can illuminate the apertures through the glass plate 7.
- Fig.3 an embodiment can be used wherein the apertures are provided by slits 47 as shown in Fig.4. While in the embodiment of Fig.4 (background) fluorescence 42 having a polarization component parallel to the slit direction is prevented to escape the slits 47, in this embodiment, fluorescence 42 having a polarization (that is direction of the electric field) along said smallest dimension can travel through the apertures formed by slits 47 towards detector 46. To distinguish between background fluorescence generated anywhere in the slit and fluorescence generated at the end of the slit a polarization filter 45 may be used, to select only a component of the fluorescence generated at the end of the slit.
- a polarization filter 45 may be used, to select only a component of the fluorescence generated at the end of the slit.
- Fig.4 shows the embodiment for this case and Fig.5 shows how the polarizer in front of the detector can be used to switch between a large and a small detection volume.
- a beam of excitation light (41) is illuminating the slits (47) (for example a wiregrid polarizer).
- the excitation radiation can travel through the slits without being substantially suppressed, because the (TE polarized) excitation wavelength is too short to be suppressed by the wiregrid, or because the excitation beam is TM polarized such that it is not suppressed by the wiregrid.
- a lens (43) placed behind the wiregrid is used to collect and focus the emitted fluorescence (42) onto a detector (46). Between the lens and the detector, a detection filter (44) (that blocks the excitation light) and a polarizer (45) are placed (note that the order of 43,44 and 45 can be mixed). Preferably, the polarizer (45) can be either rotated, or it can be easily removed.
- Fig.5 shows the effect of removing the polarizer (45) behind the wiregrid.
- the figure at the top shows the combined detection + excitation efficiency with a polarizer behind the wiregrid, placed such that it blocks the polarization that would normally transmit through the wiregrid without being suppressed.
- the maximum detection efficiency is 50%, because the polarizer will suppress at least 50% of the fluorescence.
- the detection volume is limited by the suppression of the fluorescence, yielding a small detection volume.
- the detection volume can be increased by removing the polarizer. This results in the efficiency as shown in the lower image in Fig.5, where can be seen that the total efficiency is high over the full distance.
- Fig.4 If the embodiment in Fig.4 is only used for achieving a small detection volume, it is possible to remove the detection filter (44) completely, because in this case the polarizer 45 will block all light that is polarized such that it can travel through the slits without being suppressed (and this can include the excitation light).
- a glass plate (not shown) on the detection side of the slits, in order to prevent background signals to be generated between the aperture exit and the detector.
- a computer program may be stored/distributed on a suitable medium, such as an optical storage medium or a solid-state medium supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems. Any reference signs in the claims should not be construed as limiting the scope.
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- Health & Medical Sciences (AREA)
- Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
- Physics & Mathematics (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating, Analyzing Materials By Fluorescence Or Luminescence (AREA)
Abstract
Description
Claims
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US12/519,800 US8039818B2 (en) | 2006-12-21 | 2007-12-18 | Sub wavelength aperture |
JP2009542362A JP5069312B2 (en) | 2006-12-21 | 2007-12-18 | Subwavelength aperture |
CN200780047833.1A CN101568811B (en) | 2006-12-21 | 2007-12-18 | Sub wavelength aperture |
EP07859435.5A EP2097724B1 (en) | 2006-12-21 | 2007-12-18 | Sub wavelength aperture |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP06126760.5 | 2006-12-21 | ||
EP06126760A EP1936340A1 (en) | 2006-12-21 | 2006-12-21 | Sub wavelength aperture |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2008075289A1 true WO2008075289A1 (en) | 2008-06-26 |
Family
ID=37875687
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/IB2007/055208 WO2008075289A1 (en) | 2006-12-21 | 2007-12-18 | Sub wavelength aperture |
Country Status (5)
Country | Link |
---|---|
US (1) | US8039818B2 (en) |
EP (2) | EP1936340A1 (en) |
JP (1) | JP5069312B2 (en) |
CN (1) | CN101568811B (en) |
WO (1) | WO2008075289A1 (en) |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20030036204A1 (en) * | 2001-08-14 | 2003-02-20 | Stark Peter Randolph Hazard | Surface plasmon enhanced illumination system |
US20060209413A1 (en) * | 2004-08-19 | 2006-09-21 | University Of Pittsburgh | Chip-scale optical spectrum analyzers with enhanced resolution |
Family Cites Families (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP3862845B2 (en) * | 1998-02-05 | 2006-12-27 | セイコーインスツル株式会社 | Near-field optical probe |
US6485703B1 (en) * | 1998-07-31 | 2002-11-26 | The Texas A&M University System | Compositions and methods for analyte detection |
AU5560699A (en) * | 1998-08-13 | 2000-03-06 | U.S. Genomics, Inc. | Optically characterizing polymers |
ES2464532T3 (en) * | 2001-04-19 | 2014-06-03 | The Scripps Research Institute | Methods and compositions for the production of orthogonal pairs of tRNA-aminoacyl-tRNA synthetase |
US7399445B2 (en) * | 2002-01-11 | 2008-07-15 | Canon Kabushiki Kaisha | Chemical sensor |
JP3897703B2 (en) * | 2002-01-11 | 2007-03-28 | キヤノン株式会社 | Sensor device and inspection method using the same |
JP2003241101A (en) * | 2002-02-18 | 2003-08-27 | Olympus Optical Co Ltd | Microscope |
WO2004027093A1 (en) * | 2002-09-19 | 2004-04-01 | The Chancellor, Master And Scholars Of The University Of Oxford | Molecular arrays and single molecule detection |
JP2004163122A (en) * | 2002-11-11 | 2004-06-10 | Univ Waseda | Minute aperture film, analyzer for interaction between biomolecules, and its analyzing method |
EP1757920A4 (en) * | 2004-06-11 | 2010-07-07 | Univ Gifu | Optical waveguide |
EP1607737A1 (en) | 2004-06-17 | 2005-12-21 | Patrick Hunziker | Device and method for detection and measurement of nucleic acid strands in solution |
US7511285B2 (en) * | 2004-07-16 | 2009-03-31 | The Charles Stark Draper Laboratory, Inc. | Methods and apparatus for biomolecule identification |
-
2006
- 2006-12-21 EP EP06126760A patent/EP1936340A1/en not_active Ceased
-
2007
- 2007-12-18 US US12/519,800 patent/US8039818B2/en not_active Expired - Fee Related
- 2007-12-18 CN CN200780047833.1A patent/CN101568811B/en not_active Expired - Fee Related
- 2007-12-18 JP JP2009542362A patent/JP5069312B2/en not_active Expired - Fee Related
- 2007-12-18 WO PCT/IB2007/055208 patent/WO2008075289A1/en active Application Filing
- 2007-12-18 EP EP07859435.5A patent/EP2097724B1/en active Active
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20030036204A1 (en) * | 2001-08-14 | 2003-02-20 | Stark Peter Randolph Hazard | Surface plasmon enhanced illumination system |
US20060209413A1 (en) * | 2004-08-19 | 2006-09-21 | University Of Pittsburgh | Chip-scale optical spectrum analyzers with enhanced resolution |
Also Published As
Publication number | Publication date |
---|---|
US20100072397A1 (en) | 2010-03-25 |
EP2097724B1 (en) | 2014-05-07 |
EP1936340A1 (en) | 2008-06-25 |
US8039818B2 (en) | 2011-10-18 |
JP2010513914A (en) | 2010-04-30 |
JP5069312B2 (en) | 2012-11-07 |
CN101568811B (en) | 2013-12-25 |
EP2097724A1 (en) | 2009-09-09 |
CN101568811A (en) | 2009-10-28 |
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