SYSTEMS AND METHODS FOR
FILTER BASED SPECTROGRAPHIC ANALYSIS
BACKGROUND OF THE INVENTION
Related Applications
This utility application claims priority to U.S. Provisional Patent
Application Serial No: 60/267,329, filed February 8, 2001 and to U.S. Utility
Application Serial No.: 09/939,887, filed August 27, 2001.
Field of the Invention
This invention relates to spectroscopy, in particular, devices and methods
for spectrographic analyses that use filters to select wavelengths of electromagnetic
radiation for measurement.
Description of Related Art
Spectroscopy can be characterized as the study of relationships between
absorption and/or emission of electromagnetic radiation by certain substances as
a function of the wavelength of the radiation. Absoφtion spectroscopy is in
widespread use for the detection and identification of substances because a substance absorbs electromagnetic radiation better at certain wavelengths than at
others. When a substance is exposed to a poorly absorbed wavelength of electromagnetic radiation, much of that radiation is reflected or transmitted back
into the surrounding medium. A photodetector nearby can detect the radiation, and the amount of radiation can be quantified. In contrast, when a substance is exposed
to an efficiently absorbed wavelength, little of that radiation is reflected into the surrounding medium, and consequently, the amount of radiation detected is less
than for a poorly absorbed wavelength. Measurements are typically made over a
range of wavelengths, and can include very short wavelengths (e.g., gamma- rays or x-rays) to very long wavelengths (e.g., radio frequency radiation). The
relationship between radiation intensity and wavelength is herein termed a
"spectrum." As used here, the term "spectrum" includes, but is not limited to
absorption, fluorescence, Raman, emission, or any other form or type of
electromagnetic radiation. For many analytical applications, wavelengths in ultraviolet, visible and/or infrared ranges are especially useful.
Individual substances either absorb or emit characteristic wavelengths of
electromagnetic radiation. Each substance thus has a characteristic spectrum,
which can be used to identify and/or quantify the amount of a particular substance.
Many volumes in the spectroscopic literature are devoted to the presentation of data
regarding spectra of individual substances.
However, existing methods and apparatus have several drawbacks. Most
spectroscopic apparatus rely upon varying the wavelength of emitted radiation from a radiation source by means of a dispersion device such as a prism or a diffraction
grating. A dispersion device decomposes electromagnetic radiation of
heterogeneous wavelengths into spatially resolved beams of fairly monochromatic radiation. The dispersion is achieved as follows: An electromagnetic radiation is
collimated in a beam to allow the beam to fall onto a prism or grating under
appropriate angle of incidence. Radiation of various wavelengths present in the
beam interferes with such a dispersion device in a wavelength-dependent manner.
This produces a plurality of fairly monochromatic beams radiated under various,
wavelength-dependent angles. Each beam is collected onto the surface of a
photosensitive device (such as a photo-multiplying tube, also called PMT, or
photo-diode, or photo-sensitive film). The intensity of monochromatic light in
such a beam is analyzed as the function of spatial position of the beam. The
position is directly related to the wavelength in the beam. This way of spectra acquisition is broadly employed in various spectrophotometers and spectrographs.
A major drawback of this approach is a high cost for such instrumentation, which
is to a large extend due to a need for precise alignment of optical elements.
A source of electromagnetic radiation (e.g., a light source) produces a beam
of radiation that enters a dispersion device. By way of example, a prism separates
the different wavelengths at different angles depending on the index of refraction
of each wavelength as it is transmitted through the prism. In the case of visible
light, the result can be a "rainbow." To expose an analyte sample to a particular wavelength, the prism is adjusted so that the angle of refraction of the radiation
directs a relatively narrow range of wavelengths to the sample for spectroscopic
measurement. To obtain a spectrum, the wavelength is varied by rotating the prism
to direct other wavelengths to the sample. Similar methods can be applied to
diffraction gratings. These processes are relatively slow, in that the rate of change of wavelength of illuminating radiation must be sufficiently slow to permit accurate
measurement of absoφtion at each wavelength.
The length of time required to obtain a spectrum over a desired range of
wavelengths depends upon the range desired, the discrimination between
wavelengths, and upon the number of samples to be analyzed. For analyses of
multiple samples, traditional spectroscopic methods can be impractically long.
Moreover, prisms and diffraction gratings must be aligned carefully and
misalignment can result in errors that may be difficult to detect.
SUMMARY OF THE INVENTION
To overcome these and other disadvantages of traditional spectroscopic
devices and methods, certain embodiments of this invention use a plurality of
narrow-band pass filters to select wavelengths of electromagnetic radiation for
analysis. Each filter can be associated with an individual detector, for example, a charge coupled device ("CCD"), forming a "filter/detector unit". Radiation emitted
by a sample can penetrate through a filter and can be detected and/or quantified and can be displayed on an output device and/or stored in electronic form on a
computer. The filter can absorb radiation of other wavelengths, preventing those
wavelengths from being detected. Additional filters having desired transmittance
at other, selected wavelengths can be used simultaneously to detect absoφtion at
those desired wavelengths.
Multiple filter/detector units can be placed in a one- or two-dimensional
arrangement relative to each other, permitting the simultaneous measurement of
absorbed radiation at a number of different wavelengths from a single sample of
the substance to be analyzed. Outputs from each detector can be displayed along,
for example, a vertical axis of a two-dimensional plot, and the band-pass
wavelength of the filter can be displayed along a horizontal axis, for example,
similar to a conventional spectrogram. Thus, a spectrum can be obtained over a
desired range of wavelengths. Addressable arrays of samples can be analyzed in
an automated fashion. A series of samples can be applied to a substrate, each
sample having a unique identifier, either position on the array, or by way of a
unique chemical marker. Systems for spectrographic analysis can include servo-
controlled probes that can acquire spectrographic information from each of a
plurality of samples so arrayed.
It can be readily appreciated that similar strategies can be employed for
emission, fluorescence, Raman, and any other kind of spectra, and other types of
plots (e.g., three-dimensional displays) can be readily prepared.
In certain embodiments, filters can be chosen to permit passage of a
relatively narrow wavelength band of radiation. Such embodiments can be useful
in situations in which a desired spectrographic feature is narrow.
In certain other embodiments, filters can be chosen to permit passage of a relatively wide wavelength band of radiation. Such embodiments can be useful in
situations in which desired spectrographic features are broad, or in which the
desired information has sufficiently high intensity and is not masked by signals at
other wavelengths within the band detected.
In yet other embodiments, a portion of a spectrum can be obtained using
filter/detector units having wavelength bands that are sufficiently near each other
to provide substantially complete coverage throughout a desired wavelength range.
In other embodiments, it can be desirable to select only certain portions of a
spectrum for analysis.
In additional embodiments of this invention, filter/detector units can include
waveguides, including light pipes to transmit radiation from a sample to a remote
detector.
Many configurations of sample, sample substrate, waveguides, focusing
lenses and detectors are possible. In certain embodiments, a plurality of samples can be prepared on a substrate in an array, and samples can be "read" sequentially.
Certain embodiments employ lenses or other means to focus radiation emitted by a sample onto a waveguide for transmission to a detector. Focusing can
increase the intensity of the signal detected and/or can decrease the amount of radiation arising from other samples in an array ("parasite radiation") which can
confound the analysis of certain spectrographic features.
Spectrographic information from small samples or a portion of a sample
can be obtained using the above strategy along with microscopes. Resolution of
microscopic detection of spectra can depend upon the wavelengths of interest, with
features in low wavelength portions of the electromagnetic spectrum (e.g.,
violet/ultraviolet) permitting finer detail than for features having longer
wavelengths (e.g., infrared).
In other embodiments, the filters can be miniaturized and arranged in a one-
or a two-dimensional array to permit the simultaneous measurement of absoφtion
at different wavelength bands of a relatively small sample.
In yet other embodiments of this invention, arrays of miniaturized
filter/detector units can be formed as a probe and can be positioned sequentially
over different samples. Such embodiments can be especially desired for
spectrographic analysis of multiple samples on a substrate.
In yet further embodiments, a plurality of arrays of miniaturized
filter/detector units can be used simultaneously to obtain spectrographic analyses
of a multiplicity of samples simultaneously. In certain other embodiments, the filters can be of fixed band-pass, or alternatively, in other embodiments, can be made "tunable" using electric field-
sensitive liquid crystal materials and/or any other materials possessing the desired,
similar optical and/or electrical properties.
The apparatus and methods of this invention can avoid many of the
problems facing conventional spectrophotometric methods and apparatus. In
situations in which the different filters have fixed wavelength band ranges, the
problems of optical alignment can be reduced. Because such filters can be made
reproducibly, wavelength drift can be minimized. Moreover, the lack of a
requirement for sophisticated moving parts can permit manufacture of relatively
inexpensive, yet accurate spectrographic devices.
The use of multiple filter/detector units can permit the simultaneous
measurement of a desired spectrum or portion thereof, which can substantially reduce the length of time required for spectrographic analyses. By providing
accurate rapid analyses, the devices and methods of this invention can permit study
of volatile and/or fragile analytes. By way of example, an analyte that is easily
vaporized can be detected sufficiently rapidly to permit acquisition of a broad range
of wavelengths simultaneously. In contrast, prior art dispersion based methods can
suffer from artifacts in the spectrum due to loss of sample during the analysis.
Specifically, later-measured wavelengths can have artificially low signal intensity
due to loss ofthe analyte, and the true relationship between peak intensities can be misrepresented. Similarly, for analytes that are labile, i.e., that are fragile and can
degrade easily, the devices and methods of this invention can provide improved
spectra. As with volatile analytes, prior art dispersion based methods and devices
can result in later-measured wavelengths being under represented relative to
earlier-measured wavelengths. .Moreover, using the devices and methods of this
invention, spectra can be obtained under a variety of different ambient conditions including reduced temperature and/or chemical milieu. Thus, conditions can be
selected that can reduce artifacts and result in more accurate, reproducible
spectrographic analyses.
Devices and methods of this invention can be used for analyte detection,
identification of substances for materials science applications, and astrophysical
studies of radiation emitted by remote objects. For example, gamma-radiation and
x-radiation can provide important information concerning stars, galaxies quasars,
neutron stars and other astrophysical phenomena. Infrared and/or radio frequency
detectors can be useful for studying features opaque to visible radiation, including
surface features of planets having atmospheres.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described with respect to the particular embodiments
thereof. Other objects, features, and advantages of the invention will become apparent with reference to the specification and drawings in which:
Figures 1 a and 2b depict detection of intensity of electromagnetic radiation
simultaneously at different wavelengths, using a linear array of this invention comprising filters and detectors.
Figures 2a and 2b depict detection of intensity of electromagnetic radiation
simultaneously at different wavelengths, using a two-dimensional array of this
invention comprising filters and detectors.
Figures 3a - 3b are drawings depicting an embodiment of this invention for
the collection of electromagnetic radiation from a sample. Figure 3a depicts an
embodiment having lenses and Figure 3b depicts an embodiment not having lenses. Figure 4 depicts another embodiment of this invention where illumination
ofthe area under analysis is performed using waveguides.
Figure 5 depicts an embodiment of this invention for the collection of
electromagnetic radiation from a sample using a focusing system.
Figure 6 depicts an embodiment of this invention using a system of filters
of known spectrographic opacity positioned in front of a CCD.
Figure 7 depicts an embodiment of this invention for collecting spectra
from a sample using filters of known spectrographic opacity.
Figure 8 depicts an embodiment of this invention for microscopic
spectrographic characterization of samples. Figures 9a - 9b depict an embodiment of this invention for simultaneous
spectroscopic characterization of several areas. Figure 9a is a top view depicting
several sample detection areas arranged in circular array. Figure 9b is a side view
of the reader head.
Figure 10 depicts an embodiment of this invention for simultaneous
spectroscopic characterization of several areas of a transparent sample.
Figure 11 depicts an alternative embodiment of this invention for
simultaneous spectroscopic characterization of samples.
Figure 12 depicts an embodiment of this invention having a double beam
spectrophotometer.
Figure 13a- 13d depict embodiment ofthis invention in which waveguides
of different sizes and or shapes are arranged. Figure 13a depicts an embodiment
comprising a bundle of waveguides having circular cross-sections. Figure 13b
depicts a bundle of waveguides having rectangular cross-sections. Figure 13c
depicts a bundle of waveguides having hexagonal cross-sections. Figure 13d
depicts a bundle of waveguides having triangular cross-sections.
Figures 14a - 14b depicts an embodiment of this invention in which a
plurality of waveguides carries electromagnetic radiation to a plurality of detectors
arranged in a three-dimensional array. Figure 14a depicts several waveguides with
detectors. Figure 14b depicts a higher density of waveguides and detectors than in Figure 14a.
Figure 15 depicts an embodiment of this invention in which a series of
samples on a substrate are detected using a filter-based spectrographic probe.
Figure 16 depicts a schematic representation of an embodiment of a
spectrographic reader and system ofthis invention.
Figure 17 depicts a schematic representation of a rights-enabled device with trusted computing space used with the reader and system ofthis invention.
Figure 18 depicts a schematic representation of a spectrographic reader and
system with optional digital rights management components.
Figures 19a and 19b depict a system of this invention for analyzing
spectrographic information from a plurality of samples in an addressable array.
DETAILED DESCRIPTION OF THE INVENTION
Electromagnetic radiation coming from a sample or in a beam can provide
valuable information on chemical and physical properties of matter in that sample.
Acquisition of spectrographic information is a broadly applied means for detecting, identifying and/or characterizing samples or the sources of electromagnetic
radiation. Techniques for acquisition and analysis of spectral information is called
spectroscopy. Use of the systems and methods disclosed herein have broad
applications in biology, healthcare, agricultural research, pharmacology, drug
search, drug discovery, biomedical research including human immunodeficiency virus (HIV), genetic testing, blood screening, genomics, andproteomics. Examples
of some ofthe biomolecules that can be of relevance include DΝA, RΝA, lipids,
nucleotides, proteins, peptides, amino acids, sugars, polysaccharides, hormones,
neurotransmitters, vitamins, regulatory factors, metabolic intermediates, antibodies,
and combinations ofthe above. Some embodiments ofthis invention can be useful for assessing relationships between gene expression, protein synthesis, and
biological function of gene expression and protein synthesis. Systems and methods
of this invention can also be used to assess the roles, for example, of
neurotransmitters, hormones, and enzymes in health and disease.
Systems and methods of this invention can also be used to provide a
plurality of analyses in a simple assay procedure. Biochips can be read using the
systems of this invention that can provide identification of microbes including
viruses, bacterial, bacterial products, toxins and plasmids, fungi, fungal products
and fungal toxins.
In certain embodiments, this invention includes devices and methods for
using those devices for spectrographic analysis. In general, spectrographic analysis
of samples can be by way of a plurality of filters andphotodetectors associated with
each other to detect a portion ofthe overall spectrum at one location relative to a
sample. Other filters and detectors can be used to detect other portions of the
overall spectrum from the same sample. Figure 1 depicts a scheme illustrating
certain embodiments of this invention. A series 10 of individual filter/detector
units 14, 15, 16, 17, 18 and 19 are arrayed linearly over a sample (not shown).
Each of the filter/detector units 14 - 19 has a different wavelength band pass
characteristic. Electromagnetic radiation from the sample is collected by each of
the filter/detector units 14 - 19 is transmitted to a display device and produces
spectrographic plots of wavelength bins 20 - 25. Each of spectrographic plots in
wavelength bins 20 - 25 is a graph ofthe intensity of detected radiation (I) on the
vertical axis and the wavelength of radiation detected be each ofthe filter/detector
units 14 - 19. Thus, each filter/detector unit captures a wavelength band
corresponding to a portion of the spectrum obtained. Figure lb depicts the
information shown in Figure 1 a but superimposed to show the entire portion ofthe
spectrum obtained. As with Figure la, the vertical axis displays the intensity of
radiation in wavelength bins 20 - 25 as detected by each of filter/detector units 14 -
19.
Figure 2 depicts a scheme for obtaining spectrographic information ofthis
invention using a two-dimensional array 40 of filter/detector units 1 - 9. As with
Figure 1, Figure 2a depicts radiation captured by units 1 - 9 that is displayed on a
series of graphs 50 of the intensity of radiation on the vertical axis and the
wavelength bin captured by the filter/detector units 1 - 9. Figure 2b depicts a
composite spectrum of information captured by detector array 40. The
spectrographic information is then expressed as a smooth curve 60, which
represents an estimate ofthe overall spectrographic features detected.
Using these devices and methods, spectrographic information can be obtained from samples without the necessity of varying the wavelength detected
over time as in conventional spectrographic analyses. Obtaining spectra is, in
general, accomplished by measuring the intensity of radiation that passes through a plurality of filters, each having a different wavelength band pass characteristics.
Each filter is associated with a detector that can determine the amount of radiation
reaching the detector. By measuring the amount of radiation reaching each
detector, the intensity of radiation at different wavelengths can be determined. By comparing the intensity of detected radiation with the wavelength band pass
characteristics ofthe filters, a spectrum or portion of a spectrum can be obtained,
and can be displayed and/or stored in electronic form for further analysis.
Acquisition of spatially resolved information can be desirable to
characterize a heterogeneous sample or a cross-section ofan electromagnetic beam. The use of pre-defined spatial arrangement of optical elements of this invention
represents an improvement over the existing devices and methods for acquiring
spectrographic information. In particular, collecting of light from a defined
position onto a set of optical filters of known opacity, each filter being arranged in
a pre-defined position in front of a detector, can be used for acquiring spatially
resolved spectrographic information. This arrangement of elements can be used
with infrared spectroscopy, fluorescence spectroscopy, surface-plasmon resonance,
Raman spectroscopy or any other methods for analyzing electromagnetic radiation.
In certain embodiments of this invention, microscopic analysis of samples by infrared, fluorescence, surface plasmon resonance, and Raman spectroscopy can be achieved.
In certain embodiments, radiation analyzed can include "second harmonic
generation" and/or "sum frequency generation." With highly intense radiation,
typically, though not exclusively achieved with laser sources, a portion of the
scattered radiation can be converted into radiation having alternate wavelengths. For example, some radiation can be converted into radiation having l the
wavelength ofthe incident radiation (or twice the frequency), 1/4 the wavelength
(4 times the frequency) or more, including the entire harmonic spectrum of
electromagnetic radiation. In situations using two or more different sources of
electromagnetic radiation of different wavelengths, a portion ofthe scattered light
has a frequency being the sum of the frequencies of the incident beams. The
systems and methods of this invention can be used to resolve spectrographic
information deriving from either second harmonic generation of sum frequency
generation.
Certain embodiments of this invention are based upon collecting
electromagnetic radiation emitted from a sample and the analysis of this radiation
by means of a plurality of waveguides, including but not limited to optical fibers
and the like, each waveguide adapted to be directed to a particular filter in a set of
filters that are spatially arranged in front of a plurality of detectors. Elements of
such systems may include: 1) One or more fiber bundles, which collect electromagnetic radiation
emitted from a portion of a sample and transmit this radiation to a detector;
2) A set of filters of known opacity that are spatially arranged, in
accordance with the distribution of fibers in the fiber bundle; and
3) A set of detectors to determine the intensity of radiation transmitted
through the filters. These elements and systems based upon these elements are described in the
following embodiments.
I. Filter/Detector Units
One feature of certain embodiments ofthis invention includes a plurality
of filters, each of which is associated with a detector. The filter/detector units can
then be placed so as to receive radiation emitted or reflected from a portion of a
sample. The use of multiple filter/detector units can permit the acquisition of
spectrographic information for a sample simultaneously for each wavelength being
measured.
A. Filters
The quality of the spectra obtained can depend upon the wavelength
selectivity of each filter and its spectrographic characteristics, and on whether
and/or the extent to which spectrographic ranges for each filter overlap with each
other. Filters that are useful for certain embodiments ofthis invention can have a relatively narrow band of wavelengths that can pass through each specific filter.
Among various existing filters, liquid crystal tunable filters can be particularly
useful for allowing passage of light of selected, relatively narrow wavelength
ranges. These filters can provide highly selective and tunable opacity via
orientation of molecules in a liquid crystal in response to externally applied electric fields. The manufacturing of these filters is well known in the art and is described
in the patent titled "Tunable wavelength-selective filter and its manufacturing
method", inventors: H. Takayoshi, et al., European Patent Number: EP0903615,
publication date: 24 March, 1999. This patent is herein incoφorated fully by
reference.
Other types of filters can be used, for example, including plastics or glasses
that are doped with compounds or mixtures of compounds that absorb substantially
all radiation with the exception of a desired band of wavelengths. These filters can
be individually placed over a corresponding individual detector to form a filter/detector unit.
B. Transmission of Electromagnetic Signals to Detectors The basis for detection by devices and methods of this invention is the
acquisition and characterization of electromagnetic radiation from the sample under analysis. For convenience, the term "light" herein is intended to include
electromagnetic radiation outside the visible range, and can include gamma-ray, x-
ray, ultraviolet, visible, infrared, and radio frequency radiation. Similarly, the term
"optical" as used herein includes electromagnetic radiation within and outside the
visible range of wavelengths. Thus, in situations in which the spectrographic information is within the visible range of wavelengths, the term "optical" and
"light" have their usual meanings, and when the spectrographic information is
outside the visible range, the terms "optical" and "light" are used for convenience
only, and are not intended to be limiting to the scope ofthis invention.
When the tip of an optical fiber is positioned relative to a surface of an
object, radiation emitted from this area can be collected by a waveguide. As used
herein, the term "waveguide" means a device that guides electromagnetic radiation
in a particular path. Waveguides include light pipes, optical fibers and other
devices through which radiation can be transmitted. Waveguides can have circular, square, hexagonal triangular or other cross-section shapes. A plurality of
waveguides can be arranged in a bundle and can be fused together. Waveguides
can be manufactured for a specific use or can be purchased commercially (e.g.,
Collimated Holes, Inc., Campbell, California). Commercial waveguides can have
diameters as small as 1 - 3 μm, but any desired diameter can be made using
methods known in the art. The lower limit of diameter is related to the wavelength
of electromagnetic radiation that can be transmitted through the waveguide with a desired degree of efficiency. For example, waveguides having diameters of about
0.5 μm can be used for certain visible and ultraviolet wavelengths, waveguides having diameters of about 0.1 μm can be useful for certain deep ultraviolet
("vacuum ultraviolet") and waveguides having diameters of several A can be used
for capturing soft X-ray radiation. For most puφoses herein, the terms waveguide,
optical fiber, and light pipe have the same meanings unless specifically defined differently for particular applications. In certain embodiments, radiation can be
collected directly by a waveguide. However, in certain other embodiments, it can
be desirable to focus the radiation onto the waveguide by a lens or other device. The configurations of sample, surface, waveguides, and/or lenses can be varied to
suit the particular needs ofthe analysis. In certain embodiments, focusing devices
such as lenses can incoφorate filters. In other embodiments, a focusing device can
be a separate element.
The analysis ofthe light by means of dispersion or a filter set can be used
to characterize the spectrum ofthe collected radiation. By scanning the tip ofthe optical fiber over the whole surface, spectroscopic characterization of the whole
object can be obtained. Radiation can be transmitted to a remote detector. A filter
can be placed at either end of the waveguide, and in some embodiments, the
waveguide can comprise an optical fiber incoφorating a filter, eliminating the
necessity of having separate filter and waveguide. Additionally, detectors can be
sensitive to a particular range of wavelengths, and thus, eliminate the need for a separate filter.
In yet other embodiments, filter, focusing device and waveguide can be
separate elements. In these types of embodiments, it can be possible to change the
configuration of waveguides separately from filters, permitting replacement of
waveguides that may have become damaged or are otherwise defective. Moreover, one can change the filter associated with a particular waveguide to alter the
wavelength transmitted by that waveguide to a detector.
In certain embodiments, it can be desirable for optical fibers to be
sufficiently small to permit the use of a plurality of fibers simultaneously over a
relatively small sample, such as a sample of analyte on a biochip. Such a plurality
of fibers is herein termed a "fiber bundle." The term "biochip" as used herein
means a substrate onto which an analyte of biological interest (herein termed a
"bioanalyte") is present. Such analytes include but are not limited to nucleic acids
(e.g., DNA, RNA), nucleotides, nucleosides, proteins, peptides, amino acids,
nucleic acid/protein associates, low molecular weight molecules (e.g., vitamins,
sugars and the like), bacterial toxins, enzymes, co-factors, and the like. F o r
example, for a bioanalyte application ofthis invention, if a sample is represented
as a square having sides 1 mm long each, the area of the sample will be 1 mm2.
Optical fibers 0.5 mm in diameter can permit the use of four fibers arranged in a
square, and can detect signal from the sample, with less than about 1/4 ofthe total
area being observed by each fiber. Optical fibers 0.1 mm in diameter can be
arrayed in a square comprising 100 fibers, 10 per side, each of which can observe
less than about 1/100 ofthe total sample. Optical fibers 0.01 mm in diameter can permit the simultaneous observation ofthe same sized sample (1 mm2) by 10,000
individual fibers, 100 per side, as arranged as a square, each observing less than
about 1/10,000 of the total area of the sample. By associating each fiber with a
filter having a different wavelength band pass range and/or mean, it is possible to
obtain 10,000 individual measurements at 10,000 different wavelengths simultaneously. In other embodiments, the fiber diameter can be reduced to about
1 μm or lower. Optical fibers of such diameters can permit the simultaneous
detection of 1,000,000 points on the sample. If, for example, 1000 individual
wavelengths are to be measured, then about 1000 individual measurements can be
made at each wavelength. Such replicate measurements can be averaged if desired
to estimate the intensity of radiation at each wavelength. Other densities can be
used and is limited only by the packing density and the efficiency of transmission
of radiation through the waveguides suitable for collection of radiation of desired
wavelengths. The above is intended for illustration only, and is not intended to
limit the scope ofthis invention. The above descriptions relating to square arrangements of fibers is for
illustration only, and is not the only arrangement possible. Circular, other
curvilinear, triangular, square hexagonal or linear arrangements are within the
scope of this invention. We note that with triangular or hexagonal packing of
circular fibers, the density of fibers in such fiber bundles is increased compared to square packing. Additionally, bundles of hexagonal, square, or triangular fibers can be placed, such that individual fibers can abut or be positioned near one
another and provide a desired total area of coverage. If individual fibers are close together, then the spaces between them can be minimized and the total area from
which radiation can be captured can be increased. Thus, by the use of a sufficient
number of fibers, a large portion of a spectrum of radiation emitted by the sample
can be constructed by presenting the individual data points in a display as described
above.
Waveguides or fibers can either be made according to particular needs of
diameter, length, and material. Alternatively, fibers and/or fiber arrays can be
obtained from Collimated Holes, Inc., Campbell, California. Fibers can be
obtained that are square, rectangular or circular, and can provide up to about 90%
core area (90% coverage), and can have sizes of individual fibers about 25 μm in
diameter. However, fibers with smaller sizes can be made to suit particular
puφoses. The only requirement is that the fiber be sufficiently large to transmit the
wavelength of radiation sufficiently well to be detected and/or quantified by the
photodetector.
In other embodiments, it may be desirable to use fibers of different
diameters in the same bundle. For example, for fibers having circular cross
section, even a hexagonal packing array leaves gaps between the fibers. By
interspersing fibers of smaller size, more ofthe sample are can be observed. As long as the intensity of the signal is corrected for the cross-sectional area of its
acquisition, the use of mixed sized fibers presents no substantial difficulty or
limitation to the use ofthe devices.
In certain situations, when it is not necessary to detect and/or record the
entire spectrum, one can select portions of the spectrum and use only those
waveguides and filters necessary to obtain the desired spectrographic information.
For example, in a situation in which 10,000 individual wavelengths are sufficient
to capture a complete spectrum, if about 1/10 ofthe total spectrum is desired, one
can either duplicate measurements at one or more individual wavelengths, or can
reduce the total number of fibers used, thereby permitting reduction in the size of
the sample to be detected. In this situation, the total sample size can be 0.1 mm2,
and permit the acquisition of spectrographic information of similar quality to the
information captured by an array of 10,000 fibers measuring a 1 mm2 area of
sample.
In designing fiber arrays, it can be desirable to consider the loss of signal
through the fiber after its acquisition by the fiber. It can be desirable to minimize
signal loss by keeping the total length ofthe fibers within certain limits, depending
upon the acceptable loss of signal. Additionally, the material used should be
compatible with acceptable signal losses. In general, it can be desirable to make
fibers with materials having high transmittance to the wavelengths to be analyzed. However, as long as the transmission characteristics ofthe fibers are known, it is
possible to correct results (or "standardize") the assays to take such losses into
account. Such corrections can be desirable if the transmission characteristics ofthe
fibers differs according to the wavelength of radiation.
A significant drawback in the use of conventional filter-based devices for acquisition of spectra is the necessity to collect data point-by-point. When there
is a need to collect data over a broad spectrographic range, obtaining
spectrographic data can take a long time. In contrast, by using devices and
methods ofthis invention, one can obtain spectrographic information at a plurality
of different wavelengths simultaneously, thereby increasing the speed of data
acquisition.
C. Photodetectors
In certain embodiments of this invention, photodetectors can comprise
photographic film, photodiodes, photomultiplier tubes (PMT), charge coupled
devices (CCDs) and/or any other devices known in the art. In certain situations,
it is desirable to use photodetectors that are sufficiently small so as to permit the
use of multiple detectors simultaneously. In certain embodiments, a plurality of
photodetectors can be provided having a either square, triangular or hexagonal
planar array. In such situations, the fiber bundles can have individual fibers of approximately equal length. In these embodiments, the geometrical array of the
tips ofthe optical fibers over the sample can be re-created by a geometrical array
of detectors. In this situation, there is a 1:1 two-dimensional mapping of the
optical fibers onto the photodetector array.
In other embodiments, it can be desirable to provide optical detectors out
of plane with each other. In these situations, the packing density ofthe detectors
need not be as limiting to the number of detectors is in situations in which the
detectors are in a planar array. Thus, optical fibers need not be of approximately
equal length, and a fiber bundle, detector package can be manufactured in which
a two-dimensional surface of a sample is mapped onto a three-dimensional structure of detectors. This can permit the acquisition of more data points (and
therefore more wavelengths) than practical using two-dimensional detector arrays .
The types of detectors is not necessarily limiting. Any suitable detector that
can capture and quantify electromagnetic radiation can be used with the devices
and methods of this invention. Film, diode detectors, CCDs can be used.
However, it can be desirable to use CCD devices. Charge coupled devices can be
made or obtained commercially that have sizes that are compatible with measuring
relatively small areas and relatively low intensities of radiation that characterize
some spectrographic features to be detected. Advantageously, one can use a
plurality of identical detectors to acquire an area-average spectrum, and thereby can diminish problems associated with different efficiencies of radiation capture by
different waveguide/filter/detector units. Alternatively, the sample can be moved
under the detectors, and spectrographic information can be acquired from different
areas and averaged to achieve the spectrum. Moreover, using electrically coupled
detectors permits the easier manipulation of data after its capture.
Signals from the photodetector can be transmitted to a computer, where a
program can be used to standardize the signals and to create plots of spectrographic
features, determine the total intensity of the features, and perform other
calculations. The signals can also be stored in a memory device for further
processing or comparison at a later time.
II. Detection using a Microscope or Other Optical Devices Microscopes can allow observation of small objects, but spectrographic
analysis of light emitted from a particular area of such objects represents a
challenge. In certain conventional approaches, radiation is directed, by fibers
arranged in line, onto the entrance slit of a spectrograph. A detector, such as a CCD is positioned at the exit slit of the spectrograph. The dispersed light from
each fiber is detected and addressed so as to allow one to address each fiber with
its spectrum. An image of the object is obtained by computer analysis. Such
acquisition of spectra from a surface is well known in the art (see for example
article by McClain et al., entitled 'Fast Chemical Imaging, Spectroscopy 15 (9), 28- 37 (2000), incoφorated herein fully by reference). However, the need for a spectrograph makes this approach expensive.
In certain embodiments of this invention, to obtain spectrographic
information from a small area, a near-field approach can be used without lenses or
other focusing mechanisms. A small bundle of waveguides can be positioned close
to a small area to be assayed. Measurements can be obtained at a plurality of different locations within the sample. By "scanning" the probe tip or bundle across
the surface ofthe sample, spectrographic information can be obtained from discrete
areas, stored, and can be analyzed for differences between areas, or alternatively
can be averaged to obtain overall spectrographic information for the sample.
Alternatively, a microscopic image formed using a conventional
microscope having lenses or other focusing mechanism can be projected onto an
array of filter/detector units, and simultaneous analysis of radiation from individual
elements ofthis array can be performed.
In addition to microscopes, telescopes can be used to collect radiation for
spectrographic analysis using the devices and methods of this invention. For
example, electromagnetic radiation collected from an optical telescope can be
detected using a series of filters and detectors to obtain spectra of astrophysical
phenomena, including stars, galaxies, quasars, planetary bodies, asteroids and the
like.
III. Analyte Detection
In certain embodiments ofthis invention, analytes can be detected without
separation from other analytes and/or materials. Such identification can be carried
out if the analyte has a specific or unique spectrographic feature that can be used
to identify and/or quantify the analyte. In other embodiments of this invention, detection of an analyte not having a unique spectrographic feature can be
accomplished by selecting the analyte from among a number of other species
having a similar spectrographic feature, using, for example specific binding ofthe
analyte to an analyte receptor. For example, a specific DNA species can be
selected by permitting that DNA species to bind to a complementary DNA or RNA
receptor on a substrate such as a biochip. Similarly, small molecule analytes can
be selected for analysis by use of specific receptors for those analytes. By way of
example only, detection of glucocorticoids can be accomplished by using
glucocorticoid receptors. By analogy, other receptors having specifically binding
to analytes can be used to select for those analytes.
In general, a substrate can be prepared with a number of receptors for a
desired analyte placed in an area on the substrate. A test sample containing the
analyte can be applied to the surface, where some ofthe analyte can attach to the
analyte receptor. Then detection ofthe analyte can be accomplished. In situations in which the analyte has a characteristic spectrographic feature, the detection of that spectrographic feature can indicate the presence ofthe analyte on the substrate.
To quantify the amount of analyte, a first spectrum can be obtained for the substrate with the attached receptors. The resulting spectrum is herein termed a
"blank" or "negative control." This spectrum can be stored in a memory device for
comparison with other spectra. Then, a spectrum can be obtained ofthe same area
of substrate but after attachment ofthe analyte to the receptors. This spectrum is
herein termed an "unknown" spectrum. It is apparent that one or more such
"unknown" spectra can be obtained, wherein different amounts of analytes are
attached to the receptors. In general, if more analyte is bound to the substrate, the
intensity of the spectrographic signal will be larger than situations in which less
analyte is bound. By performing studies using different amounts of analytes, the
threshold sensitivity of the method, the concentration-response relationships, and
the maximum detectable limits can easily be determined using standard methods
known to those skilled in the analytical arts.
After a desired number of unknowns have been assayed, the substrate can be treated to remove the attached analytes, and additional spectrographic
measurements can be obtained. Desirably, when all of the analyte has been
removed from the substrate, the observed spectra are substantially the same as the
spectra obtained from the same area of substrate but prior to attaching analyte
thereto.
IV. Array Readers
Certain embodiments of this invention can be used to read an array of
different samples on a substrate. Arrays of samples can be conveniently prepared
using methods known in the art. For example, a DNA chip is a surface having well
defined areas called spots or cells, onto which analytes are retained via binding to
receptors attached at these areas. Because each spot has its own well-defined position on the DNA chip surface, these DNA chips can be called DNA arrays.
The intensity of light emitted in a particular spectral range serves for the detection
of the amount of an analyte retained at each spot. Among a large variety of
chemically heterogeneous objects that require characterization by means of a
spectroscopy, those DNA chips can present a peculiar situation: On one hand,
these areas can be small and require a microscopic device for their observation. On
the other hand, the precise position of each spot makes it unnecessary to scan the
whole surface ofthe chip. Conventional DNA chip readers are expensive and, in
general, analytes are labeled with fluorescent tags and then are detected by the
fluorescence.
Array readers according to this invention can include readers of single
samples, two by two arrays of samples, linear arrays of samples, or in any other
desired configuration.
V. Raman Spectroscopy and Microscopy
Raman spectroscopy can be particularly useful for characterizing matter
including bioanalytes, because it can be performed without the necessity of
providing a label on the material to be analyzed. Raman spectroscopy is based upon
interaction of incident electromagnetic radiation with intrinsic electromagnetic
field fluctuations that can arise from intra-molecular movements or vibrations. The
interaction between incident and emitted radiation can be diagnostic of specific
materials in that most materials scatter electromagnetic radiation in very specific
ways to produces a Raman signal. Acquisition of Raman spectra from various
parts of an sample can provide valuable information on the composition of the
sample. At present, such spectral and spatial information is obtained in Raman microscopy by collecting images ofthe object through a set of filters, one filter at
a time.
One problem that has limited the use of Raman spectroscopy is that, in
general, Raman signals from most materials is weak. Two generally applicable
approaches for signal enhancement are put forward. One approach relies upon
enhancement of Raman signal by roughen metal surfaces and is known as "surface
enhanced Raman spectroscopy", or "SERS." This approach can be useful for detection of analytes in the presence of such surfaces, which include fractal
structures. Additionally, Raman signals can be further amplified by using receptors
bound to Raman enhancing structures, such as fractal structures. Such systems and
methods are described in co-pending U.S. Utility Patent Application Serial No:
09/670,453, filed September 26, 2000 entitled: "Nanoparticle Structures with
Receptors for Raman Spectroscopy" Kreimer et al., inventors, incoφorated herein fully by reference.
Another approach utilizes the enhancement of electromagnetic radiation
within cylindrical or spherical micro-cavities, hollow tubes or other optical
resonators. This approach is called "moφhology dependent resonance" or "MDR." MDR Raman spectroscopy is described in co-pending U.S. Utility Patent
Application Serial No: 09/669,369, filed September 26, 2000, entitled:
"Addressable Arrays Using Moφhology Dependent Resonance for Analyte
Detection," Yevin et al., inventors, incoφorated herein fully by reference.
Detectors, array readers, systems and methods for spectrographic analysis ofthis
invention can be advantageously used with the methods, devices, and substrates
described in the co-pending patent applications.
In addition, resonance Raman spectroscopy can be used, in which the
wavelength of excitation radiation overlaps an absoφtion band ofan analyte. This
can be combined with SERS and/or MDR. Multiphoton excitation can also be used, wherein two or more photons having relatively low energy are used to
achieve an overlap with an absoφtion band of an analyte.
The above-described methods for acquisition of spectra of electromagnetic
radiation emitted from particular areas of objects or through a cross-section ofan
electromagnetic beam can permit one to characterize simultaneously spatial and
spectral distribution of the intensity of electromagnetic radiation. It can be desirable to obtain such information rapidly, such as high throughput analysis of
bioanalytes using biochips, control for the process of manufacturing various
microscopic and macroscopic objects, and/or monitoring of pollution from an
aircraft.
VI. Addressable Array Readers
In certain embodiments of this invention, it can be desirable to provide
spectrographic analysis of a plurality of samples on a single substrate. Such
substrates having a plurality of samples thereon are herein termed "addressable
arrays." In certain embodiments, addressable arrays can be present on substantially
planar substrates, and these "biochips" can have samples thereon in places that can
be predetermined during their manufacture, or can be determined after manufacture
by the detection of a tag or marker specific for the position on the addressable
array.
Certain embodiments can advantageously use conventional two- dimensional biochips, for example, those containing DNA, protein, or collections
of small molecules, including libraries of compounds for drug development. For
two-dimensional arrays, the position of each of a plurality of samples can be addressed using X and Y coordinates. The positional information can be stored in
a memory device, and a reader controller can move a probe to the address ofthe
sample for measurement of spectrographic information. A reader probe can be
attached to a moveable arm that can be under servp control by the user or,
alternatively, a computer. After a sample address is selected, the probe and arm
can be moved to that position, the probe can be placed in position relative to that
address, and spectrographic information collected and stored. After a measurement is made, the probe can be moved to another addressable location and
spectrographic information can be collected for that sample. In this way, a plurality
of samples can be placed in an addressable array, and repeated measurements can
be made of one or more samples.
In certain other embodiments, an address on an array can be by way of a
marker or tag placed along with the sample on the substrate. Such markers can
include color coding, in which each column and can be represented by a different
color. Thus, for each address on the substrate, a unique combination of two
colored materials can be provided. Detection ofthe colors in the sample locations
can provide a desired system for relating spectrographic information to a sample's
address. Color detectors are known in the art and need not be described further.
Alternatively, unique molecules can be used as positional markers. By
providing markers having unique characteristics that can be determined, positional identification can be correlated with spectrographic information recorded by the filter-based spectrographic apparatus ofthis invention.
For color-based and chemically based identification, it can be desirable for
the marker to be detectable using a feature that does not interfere with the
spectrographic analysis of the sample under study. For example, if samples are
analyzed using Raman spectroscopy, markers having Raman spectra that do not
interfere with the sample's spectrum canbe used. Moreover, fluorescent labels can
be used if the wavelengths of fluorescent emission do not interfere with the
acquisition of spectral information of the sample. Numerous combinations of
sample variables and marker variables can be chosen and be within the scope of
this invention.
In certain other embodiments, samples can be arrayed in a one-dimensional array. In certain of these embodiments, a flexible substrate can be provided with
a source reel and a take-up reel. The substrate can be a long piece of material
having a longitudinal axis. Samples can be placed on the substrate in a linear array,
and as more samples are added to the substrate, the take-up reel can store collected
samples. The source reel can provide additional substrate for application of
additional samples. In this fashion, a plurality of samples can be collected and
brought to a reader, for example, a "strip reader" for analysis as described below.
It can be appreciated that a one-dimensional array of samples can have
individual samples with circular configuration, oblong configuration, or any other desired configuration. In certain embodiments, a sample can have an
approximately rectangular shape, having a longitudinal axis and a minor axis. The
longitudinal axis of a sample can be oriented non-parallel to or approximately
peφendicular to the longitudinal axis ofthe substrate strip. A plurality of samples
can be stored and read using a linear array of filter/detector units and can conserve
space on the substrate. It can be appreciated that other orientations of samples on
a substrate can be used without departing from the scope ofthis invention.
By using either a positional address or an address-specific marker or tag,
the spectrographic information collected can be stored along with information
about the position ofthe sample on the array or an associated marker or tag. Such
information can be annotated to include other information about the sample,
including but not limited to time of collection, type of sample, source of sample,
conditions of pretreatment ofthe sample and a wide variety of other information.
Collation of information concerning a sample and the sample's spectrographic
information can provide a powerful tool for analysis of samples and development
of new information.
VII Protection of Information
In other aspects ofthis invention, the systems and methods ofthis invention
may yield valuable proprietary information and/or personally identifiable information whose management, transmission, use and/or disclosure may be at least in part regulated by laws, rules, and/or regulations of one kind or another,
including, for example, the U.S. Health Insurance Privacy and Accountability Act
of 1996 ("fflPAA"), (PL-104-191 and rules and regulations thereinunder) and
similar laws, rules and regulations.
In one embodiment of this invention, to maintain security, privacy, confidentiality, and or control over the results obtained, it can be desirable to
incoφorate software and/or hardware for digital rights management ("DRM"). In
general, DRM technologies can associate rules governing authorized use of digital
information and consequences of such authorized use, including audit and/or usage
record creation, aggregation, and/or reporting, with digital information (regardless of format). Digital information can be protected at least in part by encryption.
Rules and/or protected information may be stored and/or transmitted in a secure
software "container" or hierarchical encrypted file structure. Secure software
container may be created and/or its contents accessed only by a trusted computer
space ("TCS"). A TCS may comprise tamper resistant hardware and/or software. A TCS may be at least in part integrated into an operating system that provides
services to, and may also at least partially control the trusted device.
Certain TCS embodiments are based on technologies currently available.
For example, in one embodiment, InterTrust Technologies Coφoration provides
TCS described in U.S. Patent Nos: 6,157,721, 6,138,119, 6,112,181, 5,982,891, 5,949,876, 5,920,861, 5,917,912, 5,915,019, 5,910,987, 5,892,900 and WIPO
Publications WO 9,810,381 Al and WO 9,901,815 Al, each publication incoφorated herein fully by reference.
Certain other commercial embodiments include available DRM technology
of ContentGuard, Inc. described in U.S. Patent Nos: 5,715,403, 5,638,443,
5,634,012, 5,629,980, each publication incoφorated herein fully by reference.
Other DRM technology of MediaDNA described in U.S. Patent No: 5,845,281,
incoφorated herein fully by reference.
Trusted computing space is a secure, tamper resistant software and/or
hardware component that incoφorates a protected computing environment ("PCE")
for evaluation and enforcement of rules governing authorized use and access of
protected information. In some embodiments, the TS manages a protected data
area ("PDA") which may, for example, comprise one or more encrypted files on
a local PC disk drive and/or may occupy a portion of solid state memory. In one
example, a PDA may be used to store cryptographic information, rules governing
authorized access, digital credentials, information documenting authorized use, and
in some embodiments, payment, budget, and/or other financial information. One
embodiment ofthe present invention includes a commercially available InterRights
™ Point software from InterTrust Technologies Coφoration. In certain
embodiments, the TCS maybe incoφorated into specialized hardware in the form of a controller chip for peripheral or other devices. One embodiment includes the
RightsChip, now commercially available from InterTrust Technologies Coφoration
and related to the InterTrust pending and/or issued patent applications cited herein.
In certain embodiments, spectrographic analysis system with incoφorated
TCS can protect information upon or near to its creation. Thus, spectrographic
information so obtained and stored can be protected from unauthorized use and
access and/or can document the circumstances of authorized use. One benefit of
incoφorating DRM technologies into the systems of this invention is that the
valuable proprietary and/or personally sensitive information can be protected for
integrity and against unauthorized use from the time of or near its creation.
In certain embodiments, an AC -DC converter, a memory device, and/or a
computer can incoφorate TCS devices. In some embodiments, a display device
can also incoφorate a TCS device. In certain of these embodiments, only one of
the above devices incoφorates a TCS, whereas in other embodiments, a plurality
of the above components incoφorate TCS devices. In those systems that incoφorate multiple TCS devices, the TCS devices may exchange encrypted
spectrographic information and/or rules associated with said information.
Spectrographic information may be transmitted to external systems in
cryptographically secure containers. One embodiment of a secure container is a
DigiBoxR secure software container that is part of a DRM software platform
commercially available from InterTrust Technologies Coφoration and related to
the InterTrust pending and issued patents cited herein.
Those skilled in the art can create applications, solutions, and services that
incoφorate digital rights management technologies that can protect data created by
the filter-based spectroscopic analysis systems disclosed herein for integrity and
against unauthorized access and use.
EXAMPLES The examples that follow are intended to illustrate embodiments of this
invention, and are not intended to limit the scope ofthe invention. For instance,
several examples depicted below include focusing devices such as lenses. Many
ofthe embodiments are contemplated that do not necessarily use focusing devices.
Moreover, the substrates depicted are for illustration only, and other types of
sample configurations are contemplated.
Example 1 : Fiber Bundle
Referring to Figure 3 a, one embodiment ofthis invention is a directed fiber
bundle probe 100 for collecting light from a small area or space 104 illuminated
via fiber 108 and directing the collected radiation by means of a bundle of fibers
112 and lenses 113 arranged by fiber collector 114. It can be desirable to arrange
head 102 ofthe probe in the shape of a cylinder, which can allow one to achieve
an MDR condition for illumination. Head 102 can be made of two materials, top
part 106 being non- transparent to avoid the loss of signal light within the fiber and
to minimize the acquisition of parasite light, and bottom part 105 being made of
glass or quartz, to provide MDR conditions. Illumination of area 104 under MDR
conditions can result in an increase ofthe intensity of electromagnetic field within
this area. The probe can be used for collecting radiation emitted from area 104 as
the result of illumination of that area by an incident electromagnetic radiation or
by emission of electromagnetic radiation from this area due to any other
phenomena. Figure 3b depicts an embodiment of this invention similar to that
shown in Figure 3a having no lenses 113.
Figure 3 also illustrates one use for probe 100. Figure 3 depicts the
collection of Raman and/or fluorescence signals from analyte 110 bound to
receptor 109, which is attached to SERS-active substrate 107. Upon excitation of
the signal, total light emitted from area 104 passes through notch filter 115 to cut
off the excitation light and prevent its capture by optical fibers 111. Radiation
passed through the filter is collected onto entrances 111 of optical fibers 112 by
lenses 113.
Example 2: Alternative Fiber Bundle I
Figure 4 illustrates another embodiment of this invention, a fiber bundle
probe 200 for collecting light from a small area or space 104 illuminated via fiber
208 and directing the collected radiation by means of a bundle of fibers 212 and
arranged by a fiber collector (not shown). This probe 200 can be used for
collecting radiation emitted from the area as the result of its illumination by an
incident electromagnetic radiation or due to emission of electromagnetic radiation
from this area 104 due to any other phenomena.
Illumination of area 104 is achieved by using light directed from a remote
light source via fiber 201: Light coming into excitation-light transmitting
compartment 202 via fiber 201 is collected from tip 203 of fiber 201 by lens 206.
Upon passage through an optical filter (which can be a notch or a holographic filter
transparent only for a desirable excitation wavelength) 205, narrow wavelength
band of light is collected by lens 207 onto tip of 209 of fiber 208. Figure 4 depicts
the collection of Raman and/or fluorescence signal from analyte 210 bound to
receptor 219, which is attached to SERS-active substrate 217. Upon excitation of
the signal, total light emitted from area 104 passes through notch filter 215 to cut
off the excitation light. Radiation passing through the filter is collected onto
entrances 221 of optical fibers 212 by lenses 213. The signal collected from area
or space 104 is the sum of signals brought to a detection device by fibers. These
fibers collect portions ofthe signal from sub-areas determined by collection lenses
of such probes. It can be desirable to use several fibers for bringing radiation to the same device for detection of electromagnetic radiation in only particular
wavelength range. The use of a plurality of fibers (3 to 10 fibers for one
wavelength range) can be sufficient to minimize problems associated with
dependence of collected spectra upon geometry. In certain embodiments, instead of having several fibers bringing information from several sub-areas, vibration or
rotation of a sample or a probe can be used to avoid the geometric dependence.
Example 3: Alternative Fiber Bundle II
Figure 5 illustrates another embodiment of this invention, a fiber bundle
probe 300 for collecting light from a microscopically small object 304.
Illumination of object 304 is achieved by light transmitted from a light source (not
shown) via fiber 308. The tip 302 of fiber 308 is in the focus of lens 303. Upon
passage through filter 305 (which can be a notch filter or a holographic filter
transparent only for a desirable excitation wavelength), a parallel beam of
excitation light, upon passage trough a semi-transparent mirror 306 is focused onto
object 304 by lens 301. Radiation emitted from object 304 is focused into a
parallel beam by lens 301, reflected by semitransparent mirror 306, directed onto
notch filter 307, and upon passage through this filter, is directed by prism 309 onto
a set of lenses 310. These lenses 310 focus the beam onto tips 311 of fibers 312.
The opposite tips of these fibers 312 are arranged via a fiber collector (not shown).
It can be desirable to use a focusing objective composed of several optical
elements instead of lens 301 for better spatial resolution.
Example 4: System for Filter-Based Spectroscopic Characterization
Figure 6 depicts a system 400 for collecting spectra of electromagnetic
radiation across entrance 401 in head 402 of a directed fiber bundle probe 403.
Fiber bundle probe 403 collects radiation entering into head 402 through entrance
401 by a plurality of lenses 404. This collected radiation is transmitted through
fibers 406 onto tips 405 of fibers 406. Fibers 406 are arranged by fiber collector
407 in such a way that at each tip 405, a delivered portion ofthe total radiation is
directed onto a pre-defined filter 408-1 - 408-9 of known opacity, each filter being
the part of set of filters 409. Each of filters 408-1 - 408-9 of the set 409 is
transparent for only radiation of particular (and known), narrow spectral range.
The intensity of radiation passing through each filter is quantified by CCD 410.
Each filter has a corresponding, pre-defined area on CCD 410, wherein filter
number 1 corresponds to the area 1 on CCD 410, filter number 2 corresponds to the
area 2 on CCD 410, etc. When the intensity detected at each area of CCD 410 is
addressed to the spectral opacity range of each filter from the set, a spectrum 420
can be obtained using computer 411.
Example 5: Acquisition of Spectra from a Small Area
Figure 7 depicts a system 500 for collecting spectra of electromagnetic
radiation emitted from a small area or space 104. Fiber bundle probe 100 for
collecting light from a small area or space 104 described in Figure 3 is used for
collecting light emitted from a sample present in this space illuminated using laser
501. The excitation light from laser 501 is transmitted to the sample via fiber 108.
Collected radiation from area 104 is directed onto a set 509 of filters 508 of pre-
defined opacity and position via a waveguide array 114. The detection of
intensities of radiation transmitted trough these filters 508 is performed by a CCD
510, each filter providing its corresponding intensity value. The position of head
106 of the directed fiber bundle probe 100 can be changed both in X and Y
directions 511 to characterize larger areas. The sample and the head can be rotated
relative to each other 512 for the avoidance of geometric dependence ofthe spectra.
Example 6: Microscopic Spectrographic Analysis
Figure 8 depicts a system 600 for collecting spectra of electromagnetic
radiation emitted from a microscopic object 304. A directed fiber bundle probe
300 described in Figure 3 collects light emitted from the sample upon its
illumination with light emitted by a laser 601 and transmitted to the object by a
fiber 308. Light emitted from the object 304 passes through a filter to cut off
scattered excitation light, and is directed onto a set of filters 609 having pre-defined
opacity and position. The detection of the intensities for the transmitted trough
these filters 608 radiation is performed by CCD 610, each a filter 608 yielding its
corresponding intensity value.
The position of head 611 of the directed fiber bundle probe 300 can be
changed in X, Y and Z directions 612 to characterize the object in horizontal
directions and to analyze its spectral properties, as dependent upon the depth of
focus.
Example 7: Array Reader I
Figure 9 depicts another embodiment ofthis invention, an array reader 700.
Figure 9a depicts a circular array of sample areas 720 with detection areas 104
therein. Figure 9b depicts a side view of reader head 700. The array of sample
areas 720 is illuminated via fibers 708 and directing the collected radiation by
means of a bundle of fibers 712 arranged by a fiber collector (not shown). This
probe 700 can be used for collecting radiation emitted from the spots ofthe array
as the result of its illumination by an incident electromagnetic radiation or due to
emission of electromagnetic radiation from these areas 104 due to any other
phenomena. Illumination of the areas 104 is achieved by using light directed
from a remote light source via fiber 701: Light coming into the excitation-light
transmitting compartment 702 via fiber 201 is collected from the tip 703 of the
fiber 201 by lens 706. Passage through an optical filter 705 (which can be a notch
or a holographic filter transparent only for a desirable excitation wavelength)
results in that light being collected by lenses 707 onto the tips 709 ofthe fibers 708.
is essentially monochromatic. This is achieved by having each tip 709 of each of
these fibers 708 in focus of a lens 707.
One use for the probe 700 is illustrated in Figure 9b, which depicts the
collection of Raman and/or fluorescence signals from an analyte 710 bound to a
receptor 719, which is attached to SERS-active substrate 717. Upon excitation of
the signal, light emitted from the areas 104 passes through a notch filter 715 to cut
off the excitation light. Radiation passing through the filter is collected onto the
entrances 721 of optical fibers 712 by lenses 713.
Example 8: Array Reader II In another embodiment ofthis invention, array reader 800, illumination of
the areas 104 can be achieved to provide an MDR conditions by using an
arrangement described in Figure 10. Figure 10 depicts a reader 800 for collecting
light from small areas 104 of an array of spots 820. These spots 820 are deposited
on a transparent substrate 830. Illumination is performed from the bottom ofthe
array, using a source of monochromatic light 840, which is converted in a parallel
beam by an optical system 850. Light coming onto the SERS-active substrate 817
with attached receptors 819 having analytes 810 bound thereto induces the
emission of light from the spots 820. The emitted radiation passes a notch filter
815 to cut off the excitation light. Radiation passing through the filter is collected
onto the entrances 821 of optical fibers 812 by lenses 813.
Example 9: Array Reader III
Figure 11 depicts an array reader 900 in which a probe 700 is used to allow
light from a laser 991 transmitted via a fiber 701 to illuminate an array 901 and to
collect a signal from spots 920 ofthis array. Collected radiation from each spot
920 ofthe array 901 is devoid ofthe contribution of excitation light, and collected
radiation is directed onto a fiber collector 907 via optical fiber bundle 906. Each
fiber of this bundle has its defined position 905 on the fiber collector 907. In
addition, the fibers ofthe bundle 906 are arranged by the fiber collector 907 in such
a way that each fiber is directed onto a pre-defined filter 908 of known opacity,
each being the part of set of filters 909. Each filter 908 ofthe set 909 is transparent
for only radiation of particular (and known), narrow, spectral range. The intensities
of delivered by each fiber and passed through each filter radiation are determined.
This is achieved by having the position for each filter and each fiber addressed on
a CCD 910. As the result of such arrangement, the spectrum of each spot can be
identified.
Example 10: Double-beam Spectrophotometer
Figure 12 depicts a double beam spectrophotometer 1000 ofthis invention,
in which light passes through a sample cuvettel 010 with an analyte 1001 in solvent
1011 and light passes through a control cuvette 1020 with the solvent 1011.
Spectrographic information is simultaneously acquired using a two heads 1002 of
a directed fiber bundle probe. Light source 1112 provides white light. This light
is collimated by an optical system 1113 and passes trough transparent bottoms
1114 of cuvettes 1010 and 1020. Each head ofthis fiber probe collects by a system
of lenses 1104 essentially all radiation entering into the heads through the entrances
1101. This collected radiation is transmitted through the fibers 1106 onto the tips
- SO - ll 05 of the fibers 1106. These fibers 1106 are arranged by a fiber collector 1107
in such a way that at each tip 1105a, a delivered portion of total radiation is
directed onto a pre-defined filter 1108-1 to 1108-36 of known opacity, each filter
being the part of set of filters 1109. Each filter 1108-1 to 1108-36 ofthis set 1109
is transparent for only radiation of particular (and known), narrow, spectral range.
The intensity of radiation passing through each filter is determined by CCD 1110.
In addition, each fiber has its correspondent pre-defined area on the CCD so as
each filter has two areas for fibers coming from the sample cuvette 1010 and from
control cuvette 1020, and these two areas have correspondent areas on CCD.
When the intensity detected at each of these areas of CCD is addressed to the
spectral opacity range of each filter from the set, a spectrum can be obtained using
a computer for both the analyte and for the solvent. Comparison between the two
spectra yields the absoφtion spectrum ofthe analyte.
Example 11: Alternative Waveguide Configurations
Figures 13a - 13d depict alternative configurations of waveguides in a probe
tip 1300 ofthis invention. In Figure 13a, a first size of waveguide 1304 is arranged
in a hexagonal array with spaces between the waveguides. A second size of
waveguide 1308 is sufficiently small to be placed within the interstices between
waveguides 1304, thereby increasing the total surface area ofthe probe 1300. In
Figure 13b, rectangular waveguides 1312 are arranged in a pattern that can
maximize the acquisition of radiation emitted by a sample. In Figure 13c, an
alternative plurality of hexagonal waveguides 1316 is arranged in an array that
maximizes the acquisition of radiation emitted from a sample. Figure 13d depicts
an alternative configuration of triangular waveguides 1320 that can maximize
acquisition of radiation emitted by a sample
Example 12: Waveguide Detector Bundle
Figures 14a - 14b depict alternative embodiments 1400 ofthis invention in
which a plurality of waveguides 1404 transmit radiation to a plurality of detectors
1408 such as photodiodes, that are arranged in series, with one photodetector
associated with each waveguide. In these embodiments, as depicted in Figure 14b, a relatively large number of waveguides and detectors can be bundled together in
a three-dimensional array 1408, thereby minimizing the volume of space necessary
to capture and transmit radiation and covert it into electrical information.
Electrical cable 1412 transmits electrical signals produced by detectors 1408 to a
processor 1416.
Photodiodes of sizes ranging from about 0.5 μm to about 1 mm are
commercially available, but smaller sized photodiodes can be made sufficiently
small to be compatible with waveguides of sizes in the range of about 1 nm or greater. It is not necessary that the photodiodes have diameters comparable to
those of waveguides. As depicted in Figure 14b, photodetectors having diameters
larger than the waveguide can be packaged in a three-dimensional array, wherein
different planes of photodetectors have waveguides of different lengths. Thus, a
large number of individual photodetector/waveguide pairs can be packaged in a
relatively small space, making the reader portable.
Example 13: Strip Detector
Figure 15 depicts another alternative embodiment ofthis invention 1500 in
which a series of samples 1504 are arrayed along a strip of a substrate 1508.
Additional portions of strip 1508 are depicted in a source reel (not shown) and a
take-up reel (not shown), which contain additional samples therein. A reader probe
1512 is depicted near each sample 1504. Reader probe 1512 is placed over each
sample 1504 and spectrographic information obtained at a plurality of wavelengths
a - e by a plurality of individual waveguides with filters 1512 a - 1512 e selective
for wavelengths a - e in each sample 1504. Strip of substrate 1508 can be moved
relative to reader probe 1512 so that each of samples 1504 can be read by reader
probe 1512. In this way, a plurality of samples can be collected, stored and
transported to an analysis system for spectrographic analysis of a large number of
samples.
The samples can be either substantially circular, oblong, or linearly
arranged wherein the sample can have a longitudinal axis and a minor axis, and wherein the longitudinal axis of the sample is arranged approximately
peφendicular to the axis ofthe strip. In this way, a plurality of samples having a substantial number of sites for spectrographic measurements can be placed on the
strip and to be read by the strip reader. However, it is apparent that the longitudinal
axis of a sample need not be substantially peφendicular to the longitudinal axis of
the substrate. A variety of orientations of samples on such strips can be used with satisfactory results.
Example 14: Reader System I
Figure 16 depicts a schematic representation of a system 1600 for
filter/based spectrographic analysis. Sample 1604 is shown relative to waveguide
1608 and detector 1612 having a filter associated therewith (not shown). Electrical
signals from detector 1612 are transmitted to alternating current - direct current
(AC -DC) converter 1620, where the signal is digitized. Digitized information is
transmitted to memory device 1624. Information in memory device 1624 is
transmitted to and/or from computer 1628 for analysis, and the analyzed
information is then transmitted to plotter 1632 for display.
Example 15: Reader System II
Figures 17 and 18 depict embodiments ofthis invention incoφorating rights
enabling devices. Figure 17 depicts a rights-enabled device 1700 having an input-
output interface 1705, a storage device 1710 with a protected data area 1720, a
trusted computing space 1730 having a protected computing environment 1740
therein.
Figure 18 depicts an embodiment of this invention incoφorating rights-
enabled devices described in Figure 17. Sample 1604 is shown in relation to
waveguide 1608 and detector 1612. Electrical signals from detector 1612 are
transmitted to alternating current-direct current (AC-DC) converter 1620 having
a trusted computer space (TCS) 1730. Digitized information from AC-DC
converter 1620 is transmitted to memory device 1624 having trusted computer
space 1730. Information from memory device 1624 is exchanged with computer
1628 having trusted computer space 1730. information is transmitted from
computer 1628 to display device 1632.
Example 16: System for Reading Addressable Arrays
Figures 19a and 19b depict an embodiment of this invention for reading
addressable arrays of samples on a substrate. Figure 19a depicts an addressable
two-dimensional array of samples on a substrate 1900 having 9 columns (1-9) and
8 rows (a-h). The addresses of each sample location are represented as a pair of
coordinates in the X (columns) and Y (rows) directions. The address at column 1,
row a (la) represents the positional address ofthe upper left most sample area and the address at column 9, row h (9h) represents the lower right most sample area.
Samples are provided on one or more addressable locations and the substrate.
Figure 19b depicts a system 1905 for spectrographic analysis of samples
incoφorating the addressable array of Figure 19a. Substrate 1900 is depicted in
relation to a probe tip 1910 comprising filter/waveguide/detector elements therein.
Probe tip 1910 is held by arm 1920, which is held by sleeve 1930. Arm 1920 is
slidably moveable in sleeve 1930 by an actuator (not shown) that is controlled by
computer 1960. Movement of arm 1920 toward the left of the figure place the
probe toward lower column numbers. Sleeve 1930 has a vertical element 1940 that
is fixed near the right end of sleeve 1930. Element 1940 is shown rotatable about
an axis by motor 1950. Rotation of element 1940 in the clockwise direction as
viewed from above moves the probe 1910 toward lower rows (e.g. row a), and
movement in the counterclockwise direction moves probe 1910 toward higher rows
(e.g., row f). The positions of element 1940 and arm 1920 are controlled by
computer 1960, so that a desired address can be selected from the computer. Upon
movement of probe 1910 to an addressable location, spectrographic information
is recorded and stored in computer 1960. Subsequently, probe 1910 is moved to
another address and additional spectrographic information is collected and stored
in computer 1960.
The examples depicted above are intended only to illustrate the general concepts and some embodiments of this invention, and are not intended to be
limiting. Persons of skill in the art can readily appreciate that the concepts ofthis
invention can be used to create a wide variety of different devices and methods for
spectrographic analysis. All of those variations are included within the scope of
this invention.