Patent Publication Number: US-2019170642-A1

Title: Array based sample characterization

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 14/787,953 filed Oct. 29, 2015, which is a national stage application under 35 USC 371 of International Application No. PCT/IB2014/062017, filed Jun. 6, 2014, which claims priority to U. S. Provisional Patent Application Nos. 61/834,330, filed Jun. 12, 2013, and 61/832,699, filed Jun. 7, 2013, the entire contents of which are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to methods and apparatus for detecting properties of samples, such as liquid samples, solid samples, solutions, slurries, and suspensions. 
     BACKGROUND OF THE INVENTION 
     Lensless microfluidic detection techniques have been proposed to acquire microscopic images of samples such as biological materials and cells. They operate by acquiring images of suspended samples in close proximity to a high-resolution imaging detector. Their small size has resulted in their use being proposed in a variety of life science applications, including microscopes, smart petri dishes, and point-of-care diagnostic systems. 
     SUMMARY OF THE INVENTION 
     A number of embodiments are presented in connection with the description, drawings, and claims of this application. 
     Systems according to the invention can help to inexpensively characterize small samples of a variety of different materials in different ways. These systems are applicable in research and industrial settings, such as in the development and manufacture of pharmaceuticals, personal care products, foodstuffs, pigments, and biomaterials, as well as in the areas of Metals, Mining, and Minerals (MMM). Their versatility and/or ability to characterize small samples can help to quickly develop materials and provide ongoing quality control and quality assurance in their handling and manufacture. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         FIG. 1  is a diagrammatic perspective view of a sample characterization system according to the invention that measures a refractive index of a sample, 
         FIG. 2  is a diagrammatic perspective view of a sample characterization system according to the invention that measures a refractive index of multiple parts of a sample, 
         FIG. 3  is a diagrammatic perspective view of a sample characterization system according to the invention that measures both the a refractive index and UV absorption of a sample, 
         FIG. 4  is a diagrammatic perspective view of a sample characterization system according to the invention that measures both the a refractive index and UV absorption of multiple parts of a sample, 
         FIG. 5 a    is a diagrammatic perspective view of a sample characterization system according to the invention that measures both the a refractive index and multi-angle scattering characteristics of a sample, 
         FIG. 5 b    is a diagrammatic top view of the system of  FIG. 5 a    showing a first baffle position, 
         FIG. 5 c    is a diagrammatic top view of the system of  FIG. 5 a    showing a second baffle position, 
         FIG. 6 a    is a diagrammatic perspective view of a sample characterization system according to the invention that measures both the a refractive index and multi-angle scattering characteristics of different parts of a sample, 
         FIG. 6 b    is a diagrammatic top view of the system of  FIG. 6 a    showing a first baffle position, 
         FIG. 6 c    is a diagrammatic top view of the system of  FIG. 6 a    showing a second baffle position, 
         FIG. 7  is a diagrammatic elevation view of a moving mirror accessory for sample characterization system according to the invention that can excite different parts of a sample, such as different parts of a sample gradient, 
         FIG. 8  is a diagrammatic perspective view of a sample characterization system according to the invention that measures both the a refractive index and multi-angle scattering characteristics of a sample flowing through a flow cell, 
         FIG. 9 a    is a diagrammatic perspective view of a sample characterization system according to the invention that measures both obscuration and deflection of a sample flowing through a narrow-channel flow cell, 
         FIG. 9 b    is an illustrative histogram showing the frequency of observed particles for different refractive index ranges for the system of  FIG. 9   a,    
         FIG. 10  is a set of five successive diagrammatic output images for the system of  FIG. 9 ; 
         FIG. 11  is a diagrammatic perspective view of a sample characterization system according to the invention that measures multi-angle scattering using a reference beam, 
         FIG. 12  is a diagrammatic perspective view of a sample characterization system according to the invention that measures a refractive index of a both a sample and a reference sample, 
         FIG. 13  is a diagrammatic block diagram of an embodiment of a high-throughput fluid characterization system according to the invention, 
         FIG. 14  is a diagrammatic top view of a three-detector sample characterization system according to the invention that measures both multi-angle scattering and UV absorption of a sample, 
         FIG. 15  is a diagrammatic top view of a three-detector sample characterization system according to the invention that measures multi-angle scattering, UV absorption, and viscosity of a sample, and 
         FIG. 16  is a diagrammatic perspective view of a sample characterization system according to the invention that uses an LED or broadband source and a laser line to measure absorption and scattering of a sample gradient. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIG. 1 , a sample characterization system  10  according to the invention characterizes a sample held in sample holder  12 . It includes an illumination source  15 , such as a laser positioned to shine its output radiation  16  toward the sample holder. A two-dimensional array detector  14  is positioned at least generally opposite the test vessel from the laser. Image analysis logic  18  is operatively connected to a data output of the two-dimensional array detector. This logic can be connected to and/or implemented Using a computer  19 . 
     The two-dimensional array detector  14  can be any suitable type of array, such as such as a CCD or CMOS array detector. It can be a relatively high resolution array, such as one having a pixel pitch of under around 10 microns. In one embodiment, the array is implemented using a Sony 8MP smartphone camera chip. The color separation filters have been removed in this embodiment, but they can be used in other embodiments to detect light of different wavelengths. 
     Spectral filters can also be provided between the illumination source and the two-dimensional array detector, such as by depositing them on the array detector chip or as a separate element. These filters allow the system designer to filter out noise and/or focus on one or more wavelengths of interest. As is well known, these filters can be low-pass, high-pass, or band-pass filters, or combinations thereof. Linear variable filters can also be used in some embodiments to acquire measurements at several wavelengths. 
     The sample holder can hold a sample in a number of different ways. For a liquid sample, the holder can be implemented as a cuvette, a capillary tube, a flow cell, a droplet holder or other suitable holder for a liquid sample. In one embodiment, the liquid sample holder is a square capillary tube. The liquid sample can include one of a variety of types of liquids, such as solutions, slurries, dispersions, or suspensions. 
     The sample holder can also be configured to hold a solid sample, such as a crystal or a powder. This type of holder can be implemented in a variety of different ways, such as a platform, clamp, or powder vial. Gaseous samples can also be accommodated, such as in sealed vials. 
     The image analysis logic  18  can be implemented using special-purpose hardware, such as a dedicated image processing card and/or with one or more special-purpose software programs running on one or more general-purpose computer platforms  19 . The computer can also control other functions of the instrument, such as turning the illumination source on and off and/or controlling the array detector. Although not shown in the remaining drawings for the sake of clarity these types of parts can be provided for each of the embodiments presented in the application. Similarly, although not shown in all of the remaining drawings for the sake of clarity, illumination sources are used to produce beams shown in connection with the different embodiments. 
     In operation, the illumination source  15  illuminates the sample in the sample holder  12  with a sample output beam  16 . The sample then refracts the beam by an amount related to its refractive index. This causes a resulting refracted beam to land at a position on the array along one or more of the axes that corresponds to the sample&#39;s refractive index. The image analysis logic  18  can then calculate a value of the refractive index, such as by counting pixels and/or interpolating subpixels in one or more directions. Note that while the drawings show the x-direction as being horizontal, this and other embodiments can be constructed to detect deflection in other directions. 
     Referring to  FIG. 2 , another embodiment of a sample characterization system  20  according to the invention characterizes a sample held in sample holder  12  at multiple places along the sample holder. It includes a plurality of illumination sources, such as lasers, positioned to shine their output beams  26   a  . . .  26   n  toward the .sample holder. A two-dimensional array detector  24  is positioned at least generally opposite the test vessel from the lasers. 
     This embodiment differs from that shown in  FIG. 1  in that the sample is illuminated at multiple different points along its length (y-axis). This allows readings for multiple sample points to be detected simultaneously. This type of embodiment can allow measurements at different places on non-uniform samples, such as where a gradient exists in the fluid or where the fluid is flowing through the sample holder, such as from a liquid chromatography column. It may also allow averaging to take place to reduce the effect of unintended or undesirable heterogeneity in the sample. 
     Referring to  FIG. 3 , a further embodiment of a sample characterization system  30  according to the invention characterizes a sample held in sample holder  32 . It includes a first illumination source, such as a laser positioned to shine its output radiation  36  toward the sample holder, and second illumination source, such as an ultraviolet absorption source positioned to shine its output radiation  38  toward the sample holder. A two-dimensional array detector  34  is positioned at least generally opposite the test vessel from the laser. Image analysis logic is operatively connected to a data output of the two-dimensional array detector. 
     In operation, the illumination source illuminates the sample in the sample holder  32  with a first sample output beam  36 . The sample then causes the beam to refract by an amount related to its refractive index. This causes a resulting refracted beam to land at a position on the array along the x-axis that corresponds to the refractive index. The image analysis logic  38  can then calculate the refractive index, such as by counting pixels and/or interpolating subpixels in the x-direction, 
     The system can also illuminate the sample with a second sample output beam  38 . This beam is positioned to provide a transmission measurement, such as a UV transmission measurement. The intensity of the beam received at the detector will therefore be indicative of the degree of absorption by the sample for the beam. Using filters, this measurement can be restricted to one or more spectral regions of interest. 
     The two types of measurements are performed during alternating periods in the present embodiment. It may be possible, however, to perform the measurements simultaneously in some circumstances. 
     Referring to  FIG. 4 , another embodiment of a sample characterization system  40  according to the invention characterizes a sample held in sample holder  32  at multiple places along the sample holder. It includes a plurality of first illumination sources, such as lasers positioned to shine their output radiation beams  46   a  . . .  46   n  toward the sample holder. It also includes a plurality of second illumination sources, such as ultraviolet absorption sources positioned to shine their output radiation beams  48  toward the sample holder. A two-dimensional array detector  44  is positioned at least generally opposite the test vessel from the laser. This embodiment differs from that shown in  FIG. 3  in that sample is illuminated at multiple points different points along its length (y-axis). This allows two readings each for multiple sample points to be detected simultaneously. 
     Referring to  FIG. 5 a   , a further embodiment of a sample characterization system  50  according to the invention characterizes a sample held in sample holder  52  using two or more two-dimensional array detectors  54   a,    54   b.  In this embodiment, the arrays are identical and are placed at right angles with respect to each along an upright edge, although other angles, orientations, and numbers of arrays can also be used, and different types of arrays can be mixed, such as arrays with different numbers of pixels, different pixel densities, or different spectral sensitivities. In the present embodiment, the arrays form two sides of an incomplete cube, with the sample holder being placed generally in the center of the cube, but other configurations are also possible. A beam  56  from an illumination source such as a laser is directed towards the sample holder, such as through an open side of the cube. 
     In operation, the illumination source illuminates the sample in the sample holder  52  with an output beam  56 . In the case of a liquid sample, the sample can then cause the beam to scatter in a manner that is related to the molecular weight of solutes and/or suspended particles in the sample. This generally causes scattered light to reach different parts of the array, with larger molecular weights scattering less uniformly, Image analysis logic can then calculate an effective molecular weight for the sample, such as by summing scattered light intensity from different angles detected at different locations and comparing the result to an incident beam intensity. Referring to  FIGS. 5 a  and 5 b   , optical baffles can act as a zero-degree beam stop, or they can be used to prevent stray light, such as reflections from one measurement from affecting another. 
     Referring to  FIGS. 6 a - c   , another embodiment of a sample characterization system  60  can .acquire samples from different parts of the sample holder. This embodiment differs from that of  FIGS. 5 a   -C that it allows an illumination beam  66  to illuminate the sample at different locations. 
     Referring to  FIG. 7 , a plural beam generator  70  can be implemented using a movable mirror system  70 , which includes a mirror that can move parallel to the length of the sample holder  72 , while passing through different positions  74   a  . . .  74   n.  The mirror can thus redirect a light beam  76  to different places along the sample holder. Other methods of providing a synchronous or asynchronous plural beam generator can also be provided, such as using galvanometers or multiple sources. 
     Referring to  FIG. 8 , a further embodiment of a sample characterization system  80  according to the invention includes a flow cell  82  supplied by conduits  83   a,    83   b.  This allows measurements to be performed on flowing samples, such as the output of a liquid chromatography column, or a process feed. In this embodiment, the flow cell is shown in connection with a right-angle, laser-based multi-angle scattering setup, although it can be used in types of setups. 
     Referring to  FIG. 9 , another embodiment of a sample characterization system  90  according to the invention includes a narrow-channel flow cell  92  fed with a flowing sample. This flow cell can be placed in parallel with a two-dimensional array detector  94 , which is preferably a relatively high-speed detector. A two-dimensional illumination beam  96  is then shone through the narrow-channel flow cell onto the array, preferably at least generally perpendicular to the direction of flow in the narrow-channel flow cell The illumination beam can be produced in a variety of ways, such as by shining a laser through a cylindrical lens. 
     In operation, referring also to  FIGS. 9B and 10 , when the system is flowing with no particles present, the two-dimensional illumination beam  96  produces a line image on the array (image  100   a ). An opaque particle that then flows through the narrow-channel flow cell  92 , will a obscure a portion of the beam  102  (image  100   b ). The width of the obscuration of the beam will be related to a spatial dimension of the particle. The duration of the obscuration of the beam will be related to a different spatial dimension of the particle. A second, smaller particle, for example, might therefore produce another obscuration of a portion of the beam  104 , with this alteration being narrower and of shorter duration (image  100   c ). 
     A non-opaque, refracting particle refract a portion of the beam  106  by an amount related to its refractive index. This causes a resulting refracted portion of the beam to land at a position on the array that is offset along the y-axis (image  100   d ). The extent of deflection will be related to the refractive index of the particle, and the width of the deflection will be related to the size of the particle. Obscuring particles and refracting particles can be detected at the same time, resulting in an image with both offset  106  and obscured  108  beam portions (image  100   e ). 
     The image analysis logic can derive particle dimensions from the acquired images by converting the widths and durations associated with detected particles. The image analysis logic can also derive an index of refraction for refracting particles. These results can then be stored, statistically analyzed, or otherwise processed and displayed, such as in the form of a histogram of numbers of observed particles against their refractive indices ( FIG. 9B ). 
     Referring to  FIG. 11 , a further embodiment of a sample characterization system  110  according to the invention includes a reference beam extractor  118 , such as a beam splitter, a bifurcated optical fiber, or an oscillating mirror. This extractor produces a reference beam in addition to the sample beam, which is used to perform one or more measurements of characteristics of a sample in a sample holder  112 , such as its scattering characteristics. Both beams can then be imaged by one or more two-dimensional an-ay detectors  114 . 
     The use of a reference beam can improve sample characteristics detection, by providing a baseline to compare measurements against. This baseline can compensate for a number of types of errors. For example, it can compensate for fluctuations or drift in the illumination source intensity, or in some embodiments it can provide information about the spectral content of the source before it is affected by interaction with the sample. 
     Referring to  FIG. 12 , another embodiment of a sample characterization system  110  according to the invention includes a reference beam extractor  129 , such as a beam splitter, a bifurcated optical fiber, or an oscillating mirror. This extractor produces a reference beam in addition to the sample beam. The sample beam is directed through a sample holder  122   a,  to perform one or more measurements of characteristics of a sample, and the reference beam is directed through a reference sample holder. After interaction with the respective samples, both beams can be recorded by one or more two-dimensional array detectors  124 . 
     The use of a reference sample can improve sample characteristics detection, by providing a baseline to compare measurements against. This baseline can compensate for a number of types of errors. Like a baseline from a sample beam, it can compensate for fluctuations or drift in the illumination source intensity, or in some embodiments it can provide information about the spectral content of the source before it is affected by interaction with the sample. It can also allow a sample to be compared against a known standard, such as a known component of the sample. 
     Referring to  FIG. 13 , an embodiment of a high-throughput fluid characterization system  40  according to the invention uses a probe  135  to perform successive measurements on a number of liquid samples held in different vessels, such as wells  132   a   1  . . .  132  in of a multi-well plate  132  or carousel. A negative/positive pressure drive  138 , which can include a pump or other pressure source, is hydraulically connected to one or more capillary sipper t 1 . 1 bes via a manifold. The capillary tubes are positioned proximate one or more two-dimensional array detectors  132  and illuminated by one or more illumination sources. The arrays and sources can be configured to perform any of the types of measurements presented in oLii.er embodiments of this application. 
     An off-the-shelf x-y-z stage is provided to successively position the samples under the probe, although other types of mechanisms can be used to position the vessels and probe relative to each other. Wash and waste vessels can also be provided, either in the plate, or separately. 
     In operation, the x-y-z stage begins by positioning a first of the wells below the probe to select a first sample. This sample is drawn into the capillary tube, which acts as the sample holder, and a measurement is performed. The sample can then returned to the vessel or discarded and the process repeated for another sample. Preferably, the process can be automated to run unattended. 
     Referring to  FIG. 14 , a further embodiment of a sample characterization system  140  according to the invention includes three two-dimensional array detectors  144   a,    144   b ,  144   c,  which are all oriented in the same y-direction but face inward in a spaced triangular configuration. In this case, they form an isosceles triangle with openings at each vertex. Inside the triangle is a sample holder  142  placed, in this case, at the center of mass of the triangle. 
     A first illumination source, such as a laser, provides a first beam  146   a  that is directed through the opening between the first two-dimensional array detector  144   a  and the second two-dimensional array detector  144   b,  toward the sample holder  142 , A second illumination source, such as a UV source, provides a second beam that is directed through the opening between the second two-dimensional array detector  144   b  and the third two-dimensional array detector  144   c,  toward the sample holder. The two sources are switched or strobed such that they interact separately with the sample in the sample holder during successive sampling intervals, although it may also be possible in some embodiments to perform simultaneous measurements. 
     In operation, the first source excites the sample, and the resulting scattering is detected by one or more of the three two-dimensional array detectors  144   a,    144   b,    144   c.  More specifically, the third two-dimensional array detector  144   c  detects unscattered and low-angle forward-scattered radiation, and the first and second two-dimensional array detectors detect 90° and other high angle scattered radiation. The detected scattered radiation can then be analyzed by analysis logic. The sample can also refract the beam from the first source and the resulting deflection can be detected by the first two-dimensional detector  144   a.  The second source illuminates the sample with UV radiation, and radiation that is not absorbed by the sample is transmitted to and detected by the first two-dimensional array detector  144   a.    
     While this embodiment is shown with three two-dimensional detector arrays configured in a spaced isosceles triangle with a centered sample holder in the middle, other numbers of arrays, arrangements of arrays, arrays orientations, and sample positions are also possible. 
     Referring to  FIG. 15 , another embodiment of a sample characterization system  150  accord 1 rig to the invention includes three two-dimensional array detectors  154   a,    154   b ,  154   c,  which are all oriented in the same y-direction but face inward in a spaced triangular configuration. In this case they fom 1 an isosceles triangle with openings at each vertex. Inside the triangle is a sample holder  152 , which in this case is a capillary tube placed against the first two-dimensional array detector  154   a.    
     A first illumination source, such as a laser, provides a first beam  156   a  that is directed through the opening between the first two-dimensional array detector  154   a  and the second two-dimensional array detector  154   b,  toward the sample holder  152 . A second illumination source, such as a UV source, provides a second beam that is directed through the opening between the second two-dimensional array detector  144   b  and the third two-dimensional array detector  144   c,  toward the sample holder. The two sources are switched or strobed such that they interact separately with the sample in the sample holder during successive sampling intervals, although it may also be possible in some embodiments to perform simultaneous measurements. 
     This embodiment differs from that described in connection with  FIG. 14  in that it detects scattering according to a somewhat different geometry and further allows for the measurement of viscosity as described in U.S. application Ser. Nos. 13/844,951, filed Mar. 16, 2013 (now abandoned), 13/773,259, filed Feb. 21, 2013, 13/772,310, filed Feb. 20, 2013 (now abandoned), and 13/842,378, filed Mar. 15, 2013, which are all herein incorporated by reference. U.S. application Ser. Nos. 13/884,951 and 13/772,310 were abandoned in favor of U.S. application Ser. No. 14/769,149, filed Aug. 20, 2015. In addition to detecting UV transmission of the sample, therefore, the first two-dimensional array detector also detects its viscosity by measuring how long it takes for a fluid meniscus to move through the capillary tube. 
     Referring to  FIG. 16 , a further embodiment of a sample characterization system  160  according to the invention includes a two-dimensional array detector  164  and a sample holder  162 , which in this case is a capillary tube placed proximate the two-dimensional array detector. A first illumination source, such as a laser equipped with a cylindrical lens, provides a first two-dimensional beam  166   a  that is directed toward the sample holder  162  in a first direction that can be at least generally parallel to the plane of the two-dimensional array detector and along the longitudinal axis of the capillary tube. A second illumination source, such as a UV source, provides a second beam that is directed toward the sample holder, preferably at a different angle such as at a right angle with the detector. The two sources are switched or strobed such that they interact separately with the sample in the sample holder during successive sampling intervals, although it may also be possible in some embodiments to perform simultaneous measurements. 
     In operation, the output beam of the first source causes scattering by the sample, which is detected by the array, and the output of the second source is partially transmitted through the sample, and detected by the array. This embodiment allows the two types of measurements to be performed over a sample in which a gradient exists. 
     Several embodiments have been presented above, but a number of implementations that rely on permutations of the underlying principles can be implemented. The embodiments of  FIGS. 14 and 16  can be combined, for example, to measure a wide range of scattering angles for a sample in which a gradient exists. And while particular combinations of measurements have been shown, other types of measurements, such as Raman, IR, NIR, fluorescence, and reflectance measurements can be incorporated into the different embodiments and variants thereof. Each of these measurements can be produced using a particular combination of source(s), filter(s), and/or detector(s). 
     It should also be observed that although a lens may be used to produce the beams in each of the embodiments presented above, each of them can operate without any imaging lens. The result is that systems according to the invention can be built relatively inexpensively and without the need to align or clean imaging lenses. 
     The present invention has now been described in connection with a number of specific embodiments thereof. However, numerous modifications which are contemplated as falling within the scope of the present invention should now be apparent to those skilled in the art. In addition, the order of presentation of the claims should not be construed to limit the scope of any particular term in the claims. 
     It will be appreciated that any feature of any dependent claim could be used in combination with any number of features of other dependent claims, and in any combination of features. All numbers and combinations of dependent claims are hereby disclosed, dependent from any independent claim.