WO2014137989A1 - Procédés et systèmes permettant d'obtenir une estimation améliorée de la durée de vie de luminescence - Google Patents

Procédés et systèmes permettant d'obtenir une estimation améliorée de la durée de vie de luminescence Download PDF

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Publication number
WO2014137989A1
WO2014137989A1 PCT/US2014/020149 US2014020149W WO2014137989A1 WO 2014137989 A1 WO2014137989 A1 WO 2014137989A1 US 2014020149 W US2014020149 W US 2014020149W WO 2014137989 A1 WO2014137989 A1 WO 2014137989A1
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WIPO (PCT)
Prior art keywords
decay
tau
noise
data signal
detector
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PCT/US2014/020149
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English (en)
Inventor
Scott Bruce ROSENTHAL
Original Assignee
Rosenthal Scott Bruce
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Publication of WO2014137989A1 publication Critical patent/WO2014137989A1/fr

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    • 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
    • G01N21/6408—Fluorescence; Phosphorescence with measurement of decay time, time resolved fluorescence

Definitions

  • Embodiments described herein relate generally to methods and systems for improved estimation of luminescence lifetime.
  • luminescent materials possess the property that, when stimulated or excited with light at the correct wavelengths, they will emit light at longer wavelengths, where the emitted light intensity correlates with a parameter such as, but not limited to, pH, temperature, oxygen concentration (hereinafter referred to as p0 2 ), and so on.
  • p0 2 pH, temperature, oxygen concentration
  • These materials luminesce such that, when the excitation light is turned off, the rate of decay of the emitted light, Tau ( ⁇ ), is exponential.
  • This decay rate, ⁇ also interchangeably referred to as luminescence lifetime, or simply lifetime
  • correlates with a desired measurement parameter such as, but not limited to, p0 2 .
  • Time-domain (TD) measurements typically attempt to measure ⁇ by pulsed excitation followed by collection of luminescence decay information.
  • An ideal luminescence intensity decay can be characterized by
  • FIG. 1 A illustrates how ⁇ can be calculated based on this linear relationship between t and In (— ), where the diamonds denote data points.
  • FIG. 1 A (not shown) would be a straight line with a slope of -1/ r.
  • random noise (say n t ) derived from analog circuitry can be additive to the true luminescence intensity I t , and yield the following form:
  • FIG. IB illustrates how measuring n t along with the true luminescence intensity I t can result in erroneous Tau measurements, where the solid line represents a linear regression of the ideal data of FIG. 1A, and the dotted line is the best linear regression fit for the values of
  • n t is Gaussian-distributed noise with a one-sigma level of 5%
  • Tau (ideal) is 14.00 ⁇ as determined from the solid line of FIG. IB
  • the noise- influenced Tau (dotted line) is 12.25 ⁇ .
  • applying such noise-influenced Tau measurements for determining oxygen levels results in as much as a 20% error in the p0 2 , for example reading from 250 mmHg to 300 mmHg.
  • FIG. 1A is a graph of ln(normalized intensity) vs. time for an ideal signal
  • FIG. IB is a graph of ln(normalized intensity) vs. time for the signal of FIG. 1A with (actual) and without (ideal) added random noise;
  • FIG. 1C is a graph of the difference between the ideal and actual measured ln(normalized intensity) values of FIG. IB vs. the ideal ln(normalized intensity);
  • FIG. 2 is a graph of ln(normalized intensity) vs. time for the signals of FIG. IB with and without added random noise, and with a weighting function applied to the signal with added random noise;
  • FIG. 3 is a system of the invention, according to embodiments.
  • a detector is intended to mean a single detector, multiple detectors, and/or a combination of detectors.
  • the term 'luminescence' can refer to any form of cold body radiation including chemiluminescence, electroluminescence, photoluminescence, and/or the like.
  • Photoluminescence can include fluorescence, phosphorescence, or both.
  • the noise may be of any suitable mathematical form (e.g. linear, non-linear, analog, digital, and/or the like), and may arise from any influence (e.g. electrical effects, optical, thermal, instrumentation, and/or the like) on the system.
  • the noise includes electrical noise from amplifiers in analog circuitry of a luminescence lifetime measuring system.
  • the noise includes digital noise caused by the limited resolution of the A/D, math processing, pixelization, and/or the like.
  • the noise can include an offset. In such embodiments, the offset can be removed, such as by calculating a derivative of the signal.
  • the noise takes the form n t , and modifies the detector's output signal as:
  • the measured signal is the measured signal ("measured signal” hereon).
  • the measured signal is described here as the detector signal for ease of explanation, the measured signal can arise from any component associated with the emission signal.
  • the measured signal is the analog signal from an amplification unit connected to the detector, or the measured signal is the digital signal from an A/D converter connected to the detector and/or the amplification unit, and/or the like.
  • the analysis presented below may be applied in part or whole to any of the detector and/or other components downstream of the detector, including the A/D converter, the amplification unit, and/or the like.
  • the measured signal is not saturated; in other words, the detector is working in its linear response range, as is commonly understood in the art.
  • Tau is determined as discussed earlier.
  • the nature of the logarithm transformation reduces a small percentage change in a large measured signal while exaggerating a larger percentage change in a smaller measured signal.
  • a full-scale IV signal would have 50 mV of noise (5%), while a 200 mV signal would also have 50 mV of noise (25%) riding on it.
  • the magnification of the noise with respect to the signal is best illustrated in FIG. 1C, which plots the log transformation with ideal, noise- free data versus the difference in the log transformation using the same ideal data plus noise.
  • Io i.e., the In (— ) gets more negative
  • the error due to the added random noise increases.
  • aspects of the invention overcome these drawbacks by differential weighting, effect, and/or consideration to data points corresponding to an exponential decay data depending on which part of the exponential decay curve the data point(s) lies on.
  • data points corresponding to 'earlier' portions of an exponential decay curve are weighted differently than data points that correspond to later portions of the same decay curve.
  • a weighting function is applied to the decay curve, and may be of any suitable form to achieve the benefits of the invention.
  • the weighting function may be a straight line with a negative slope, a step function, an exponential decay, and/or the like.
  • the weighting function may be a constant (e.g. a line with a predetermined slope) or a function of any suitable parameter (e.g. a line with a slope that is a function of time).
  • the suitable parameter is derived from any portion of the exponential decay curve, including, but not limited to, intensity at each data point, time at each data point, a data point number in a sequence of data points, and/or the like.
  • the weighting function may be added, subtracted, multiplied and/or otherwise combined with the exponential curve data by any suitable mathematical operation.
  • the weighting function is analog, while in other embodiments, the weight function is discrete and/or digital in nature.
  • the weighting function is a weighting parameter that is applied to each data point (i.e. each data pair of I t and time t).
  • w t is an exponential decay curve. In this manner, w t can influence the regression analysis by over-exaggerating the data pairs with the largest I t values and correspondingly, the largest w t values.
  • a closer match between the ideal (solid line) and actual/measured (dotted line) Tau values is observed in FIG. 2 as compared to FIG. IB.
  • the ideal line has a Tau of 14.00 ⁇
  • the actual line in FIG. 2 has a Tau of 13.88 ⁇ (vs. a Tau of 12.25 ⁇ for FIG. IB).
  • the p0 2 reading is now determined to be 255 mmHg, a factor of 10 reduction in error prior to weighting.
  • FIG. 3 illustrates an environment and/or system 300 within which aspects of the invention may be implemented.
  • the system 300 can be a stand-alone system or, in some embodiments, be part of and/or otherwise integrated with any suitable optical analysis system including, but not limited to, an in vivo system, an ex vivo system, an in vitro system, a spectroscopy system, a microscopy system, and/or the like.
  • the system 300 includes a computing apparatus 302, a light control 304, a light source 306, a detector 308, an amplification unit 310, an analog-to-digital (A D) converter 312, and a timing unit 314.
  • a D analog-to-digital
  • a sample holder 318 is also illustrated, although it is understood that the sample holder need not be part of the system 300, and does not affect operation of the system 300. Interconnections shown between these components by solid lines may be electrical, optical, wireless, and/or the like. Further, it is understood that some of these components may be combined.
  • the light control 304 may be integral to the light source 306 in terms of design and/or function
  • the amplification unit 310 may be combined with the detector 308, the A/D converter 312 may be combined with the amplification unit, and so on.
  • coupling optics may be employed for coupling the excitation light from the source 306 to the sample holder 318, and for coupling the emission light from the sample holder to the detector 308.
  • the coupling optics can include, but are not limited to, one or more of filters, mirrors, prisms, lens, shutters, polarizers, fiber optics/other transmission media, and/or the like.
  • the light source 306 can be any suitable light source for analyzing the sample for fluorescence lifetime, and can include, but is not limited to, one or more of an incandescent light source such as halogen lamps, a light-emitting diode, a gas discharge lamp, a CW or pulsed laser and/or other suitable monochromatic source, and/or the like.
  • the light source 306 is a pulsed laser source.
  • the light control 304 can be any suitable electronic component controllable by the computer 302 and/or the timing unit 314, and can control aspects of operation of the light source 306, including, but not limited to, triggering, output intensity, gating, and/or the like.
  • the detector 308 can be any suitable detector for detecting one or more optical signals from the sample holder 316 and/or portions of the sample holder, and can include, but is not limited to, one or more of a phototube, a photo multiplier tube (PMT), a photodiode, a charge- coupled device (CCD) sensor or camera, a complementary metal-oxide-semiconductor (CMOS) sensor, and/or the like.
  • the detector detects luminescence.
  • the detector is a silicon PIN photodiode such as, but not limited to, the Hamamatsu S5973-01.
  • the amplification unit 310 can be any suitable component capable of amplifying the output of the detector 308, and/or any aspect thereof, such as specific frequency-dependent components of the output, a subset of all pixels (when the detector output is a digital image, for example).
  • the amplification unit 310 can be controllable by the computer 302 and/or the timing unit 314.
  • the amplification unit 310 can be a single amplifier, or a string of amplifiers.
  • the amplification unit includes one or more operational amplifiers such as, but not limited to, the Texas Instruments OPA657N, the Texas Instruments OPA820, and the Linear Technology LT6230.
  • the A/D converter is operable for converting any suitable output of the detector 308 into a digital signal.
  • the A/D converter is capable of digitizing the detector 308 output at a rate significantly faster than the exponential decay associated with the luminescent material being measured.
  • the A/D converter is capable of digitizing a luminescent decay with a Tau on the order of microseconds and higher.
  • the luminescent decay is associated with a p0 2 measurement.
  • the timing unit 314 can be any suitable component capable of receiving, generating, and/or otherwise outputting timing signals for controlling the other components of the system 300 as illustrated. In some embodiments, the timing unit 314 controls at least the turning on, the turning off, and the duration of excitation of the light source 306 via the light control 304. In some embodiments, the timing unit 314 controls the rate of A/D conversions by the A/D converter 312.
  • the timing unit 314 synchronizes operation of the light source 306 (via light control) and the operation of the A/D converter 312 during at least one of the following time periods: a dark period before the light source is turned on; an excitation period when the light source is turned on; and an emission period (also referred to as the luminescent decay period) when the light source is turned off.
  • the computing apparatus 302 is configurable to analyze the output from the A/D converter to determine the Tau or lifetime as discussed above.
  • the timing unit synchronizes Tau determination by the computing apparatus 302 to period(s) with the light source off; i.e. during the emission period, as described above.
  • the system 300 is optimized for measuring luminescent materials with Tau values in the microseconds range. In some embodiments, the system 300 is optimized for measuring oxygen-sensitive luminescent materials.
  • luminescent materials include, but are not limited to tris(2,2'-bipyridine)ruthenium dichloride, Pt(II) meso- Tetra(pentafluorophenyl)porphine, Tris (4,7-diphenyl-l ,10-phenanthroline)ruthenium (II) chloride, Pt(H) meso-tetra( -methyl-4-pyridyl)porphyrin tetrachloride, platinum octaethylporphyrin.
  • Suitable Tau values corresponding to these fiuorophores can be microseconds to milliseconds.
  • Suitable A/D conversion rates can be selected based on an estimate of the Tau value being determined; for example, in some embodiments, the A/D conversion rate is selected such that at least two data points acquired for an expoential decay curve are separated by about Tau. In some embodiments, at least three data points are acquired for an exponential decay curve within time Tau.
  • the detector 308, the amplification unit 310, and the A/D converter can directly measure the entire exponential decay curve from a single excitation pulse by the light source 306.
  • the timing unit is then operable to synchronize the various components of the system 300 as described above to analyze the exponential decay fast enough to determine Tau.
  • the exponential decay obtained from the A/D converter 312 is weighted to improve Tau estimation as discussed above.
  • the output of the amplification unit 310 is weighted to improve Tau estimation as discussed above.
  • the output of the detector 308 is weighted to improve Tau estimation as discussed above.
  • Benefits of this approach allow the use of fewer optical components when emission detection occurs with the light source 306 off, thereby eliminating or otherwise alleviating the need for optical filters to block excitation light from reaching the detector 308. Additionally, since the light source can be on for a short duration of time (e.g. a single excitation pulse), photodegradation of the luminescent material is greatly reduced and/or eliminated.
  • the computer 302 can constitute at least a processor (not shown) and a memory (not shown).
  • the processor of the computer 302 can be any suitable processing device configured to run and/or execute a set of instructions or code.
  • the processor can be a general purpose processor, a central processing unit (CPU), an accelerated processing unit (APU), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA) and/or the like.
  • the processor can be configured to run and/or execute a set of instructions or code stored in the memory associated with using a personal computer application, mobile application, an internet web browser, and/or the like.
  • the processor can run and/or execute a set of instructions associated with performing numerical methods to control the system 300, to determine Tau, and/or the like.
  • the memory can be any memory (e.g., a RAM, a ROM, a hard disk drive, an optical drive, other removable media) configured to store information (e.g., one or more software applications, training course/task information, user account information, media, text, etc.).
  • the memory can include one or more modules performing the functions described herein.
  • the functions described herein can be performed by any number of modules.
  • the functions described herein can be performed by a single module.
  • the memory can also alternatively store one or more resources (e.g., software resources such as drivers, code libraries, etc.) associated with one or more of the modules.
  • Some embodiments described herein relate to a computer storage product with a non- transitory computer-readable medium (also referred to as a non-transitory processor-readable medium) having instructions or computer code thereon for performing various computer- implemented operations.
  • the computer-readable medium or processor-readable medium
  • the media and computer code may be those designed and constructed for the specific purpose or purposes.
  • non-transitory computer-readable media include, but are not limited to: magnetic storage media such as hard disks, optical storage media such as Compact Disc/Digital Video Discs (CD/DVDs), Compact Disc-Read Only Memories (CD-ROMs), magneto-optical storage media such as optical disks, carrier wave signal processing modules, and hardware devices that are specially configured to store and execute program code, such as Application- Specific Integrated Circuits (ASICs), Programmable Logic Devices (PLDs), Read-Only Memory (ROM) and Random-Access Memory (RAM) devices.
  • ASICs Application- Specific Integrated Circuits
  • PLDs Programmable Logic Devices
  • ROM Read-Only Memory
  • RAM Random-Access Memory
  • Examples of computer code include, but are not limited to, micro-code or microinstructions, machine instructions, such as produced by a compiler, code used to produce a web service, and files containing higher-level instructions that are executed by a computer using an interpreter.
  • embodiments may be implemented using Java, C++, or other programming languages and/or other development tools.

Abstract

L'invention concerne un procédé permettant de déterminer la vitesse de déclin de la lumière fluorescente émise par une matière photoluminescente en communication fonctionnelle avec une substance possédant une propriété. La lumière fluorescente est émise en réponse à la stimulation de la matière photoluminescente par une impulsion de lumière de stimulation. La vitesse de déclin est mise en corrélation avec une valeur de la propriété de la substance. Le procédé consiste à recevoir un signal de données produit en réponse à la réception de la lumière fluorescente, et à appliquer une fonction de pondération sur le signal de données pour produire un signal de données pondéré. Le procédé comprend également l'étape consistant à calculer la vitesse de déclin du signal de données pondéré.
PCT/US2014/020149 2013-03-04 2014-03-04 Procédés et systèmes permettant d'obtenir une estimation améliorée de la durée de vie de luminescence WO2014137989A1 (fr)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019093089A1 (fr) * 2017-11-13 2019-05-16 ソニー株式会社 Dispositif de traitement d'informations, procédé de traitement d'informations et système de capture d'image de fluorescence

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US5459323A (en) * 1990-01-12 1995-10-17 University Of Salford Measurement of luminescence
US20030101026A1 (en) * 2001-11-29 2003-05-29 Paul Rabinowitz System and method of data reduction for improved exponential decay measurements
US20060134644A1 (en) * 2003-10-28 2006-06-22 Dakota Technologies, Inc. Apparatus and methods for detecting target analyte
US20090216457A1 (en) * 2004-12-30 2009-08-27 Art, Advanced Research Technologies Inc. Method for improving fluorescence image contrast
US20120281204A1 (en) * 2010-01-15 2012-11-08 Mitsui Engineering & Shipbuilding Co.,Ltd. Fluorescence measurement device and fluorescence measurement method

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5459323A (en) * 1990-01-12 1995-10-17 University Of Salford Measurement of luminescence
US20030101026A1 (en) * 2001-11-29 2003-05-29 Paul Rabinowitz System and method of data reduction for improved exponential decay measurements
US20060134644A1 (en) * 2003-10-28 2006-06-22 Dakota Technologies, Inc. Apparatus and methods for detecting target analyte
US20090216457A1 (en) * 2004-12-30 2009-08-27 Art, Advanced Research Technologies Inc. Method for improving fluorescence image contrast
US20120281204A1 (en) * 2010-01-15 2012-11-08 Mitsui Engineering & Shipbuilding Co.,Ltd. Fluorescence measurement device and fluorescence measurement method

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019093089A1 (fr) * 2017-11-13 2019-05-16 ソニー株式会社 Dispositif de traitement d'informations, procédé de traitement d'informations et système de capture d'image de fluorescence
JPWO2019093089A1 (ja) * 2017-11-13 2020-11-12 ソニー株式会社 情報処理装置、情報処理方法及び蛍光画像撮像システム
US11272844B2 (en) 2017-11-13 2022-03-15 Sony Corporation Information processing device, information processing method, and fluorescence image capturing system

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