Reflection-reducing well plate

Abstract

Articles comprising containers for fluid and methods of performing optical measurements on fluids contained in such articles are generally described herein. Some articles described herein may have a design such that light supplied during the performance of an optical measurement, such as during an optical assay, is mostly or entirely directed away from the probe that supplies it. This may allow for light that is generated during the assay, such as light associated with an experimental measurement or a positive control, to make up a relatively high percentage (or all) of the light incident on the probe. Advantageously, this property may reduce the amount of background noise present in the optical measurement and / or may facilitate the performance and analysis of optical measurements for which the signal is relatively low.

Description

[0001] REFLECTION-REDUCING WELL PLATE

[0002] RELATED APPLICATIONS

[0003] This application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Application No. 63 / 512,771, filed July 10, 2023, and entitled “Reflection-Reducing Well Plate,” which is incorporated herein by reference in its entirety for all purposes.

[0004] FIELD

[0005] Articles for performing optical assays, and associated methods, are generally described.

[0006] BACKGROUND

[0007] Multiwell plates may be employed to contain fluids during optical assays. However, many such plates have designs such that an undesirably high percentage of the light present during such assays may be reflected therefrom into an optical detector, unfavorably causing a high background signal.

[0008] Accordingly, new instruments and methods that address these concerns would be beneficial.

[0009] SUMMARY

[0010] The present disclosure generally describes instruments and methods. The subject matter described herein involves, in some cases, interrelated products, alternative solutions to a particular problem, and / or a plurality of different uses of one or more systems and / or articles.

[0011] In some embodiments, an article is provided. The article comprises a container for a fluid. The container comprises a measurement portion. The measurement portion has a geometry such that less than or equal to 50% of light impinging vertically thereon reflects at an angle of less than or equal to 35° with respect to a vertical axis. A variation in a height of the measurement portion is less than or equal to 1.6 mm.

[0012] In some embodiments, a method is provided. The method comprises transmitting light through an end of a probe to a fluid positioned in a container and detecting an optical signal based on the interaction of the light with one or more species present in the fluid and / or immobilized on the probe. The container comprises a measurement portion. The measurement portion is positioned beneath the probe. The measurement portion has a geometry such that less than or equal to 50% of light impinging vertically thereon reflects at an angle of less than or equal to 35° with respect to a vertical axis. A variation in a height of the measurement portion is less than or equal to 1.6 mm.

[0013] In some embodiments, an article comprises a container for a fluid. The container comprises a measurement portion. The measurement portion has a geometry such that less than or equal to 50% of light impinging vertically thereon reflects at an angle to the vertical of less than or equal to 18° when the article is untilted. A variation in a height of the measurement portion is less than or equal to 1.75 mm.

[0014] In some embodiments, a method comprises transmitting light through an end of a probe to a fluid positioned in a container and detecting an optical signal based on the interaction of the light with one or more species present in the fluid and / or immobilized on the probe. The container comprises a measurement portion. The measurement portion is positioned beneath the probe. The measurement portion has a geometry such that less than or equal to 50% of light impinging vertically thereon reflects at an angle to the vertical of less than or equal to 18° when the article is untilted. A variation in a height of the measurement portion is less than or equal to 1.75 mm. The optical signal is detected while an article in which the container is positioned is tilted at an angle of less than or equal to 45°.

[0015] In some embodiments, an article comprises a container for a fluid. The container comprises a measurement portion. The measurement portion comprises a substrate and a coating disposed on the substrate. The coating comprises a plurality of light-absorbing particles and a polymer. The measurement portion has a geometry such that less than or equal to 50% of light impinging vertically thereon reflects at an angle of less than or equal to 35° with respect to a vertical axis.

[0016] In some embodiments, a method comprises transmitting light through an end of a probe to a fluid positioned in a container and detecting an optical signal based on the interaction of the light with one or more species present in the fluid and / or immobilized on the probe. The container comprises a measurement portion. The measurement portion is positioned beneath the probe. The measurement portion comprises a substrate and a coating disposed on the substrate. The coating comprises a plurality of light- absorbing particles and a polymer. The measurement portion has a geometry such that less than or equal to 50% of light impinging vertically thereon reflects at an angle of less than or equal to 35° with respect to a vertical axis.

[0017] In some embodiments, an article comprises a container for a fluid. The container comprises a measurement portion. The measurement portion comprises a substrate, a light- absorbing coating disposed on the substrate, and a compatibilizing coating disposed on the light-absorbing coating. The measurement portion has a geometry such that less than or equal to 50% of light impinging vertically thereon reflects at an angle of less than or equal to 35° with respect to a vertical axis.

[0018] In some embodiments, a method comprises transmitting light through an end of a probe to a fluid positioned in a container and detecting an optical signal based on the interaction of the light with one or more species present in the fluid and / or immobilized on the probe. The container comprises a measurement portion. The measurement portion is positioned beneath the probe. The measurement portion comprises a substrate, a lightabsorbing coating disposed on the substrate, and a compatibilizing coating disposed on the light-absorbing coating. The measurement portion has a geometry such that less than or equal to 50% of light impinging vertically thereon reflects at an angle of less than or equal to 35° with respect to a vertical axis.

[0019] In some embodiments, an article comprises a container for a fluid. The container comprises a measurement portion. The measurement portion has a surface roughness of greater than or equal to 0.2 Ra and less than or equal to 1 Ra. The measurement portion has a geometry such that less than or equal to 50% of light impinging vertically thereon reflects at an angle of less than or equal to 35° with respect to a vertical axis.

[0020] In some embodiments, a method comprises transmitting light through an end of a probe to a fluid positioned in a container and detecting an optical signal based on the interaction of the light with one or more species present in the fluid and / or immobilized on the probe. The container comprises a measurement portion. The measurement portion is positioned beneath the probe. The measurement portion has a surface roughness of greater than or equal to 0.2 Ra and less than or equal to 1 Ra. The measurement portion has a geometry such that less than or equal to 50% of light impinging vertically thereon reflects at an angle of less than or equal to 35° with respect to a vertical axis.

[0021] In some embodiments, a method or article as in any preceding claim is provided wherein the container is positioned in an article comprising a plurality of containers.

[0022] In some embodiments, a method or article as in any preceding claim is provided wherein the article is a multi-well plate.

[0023] In some embodiments, a method or article as in any preceding claim is provided wherein the container is a well.

[0024] In some embodiments, a method or article as in any preceding claim is provided wherein the optical signal is detected while the article is shaking. In some embodiments, a method or article as in any preceding claim is provided wherein the shaking comprises translating the container along an orbital pathway.

[0025] In some embodiments, a method or article as in any preceding claim is provided wherein the container has a geometry such that less than or equal to 50% of the light is reflected from the container into the end of the probe during detection of the optical signal.

[0026] In some embodiments, a method or article as in any preceding claim is provided wherein a center of the measurement portion is positioned less than or equal to 1 mm from a center of a portion of the container positioned vertically beneath the probe.

[0027] In some embodiments, a method or article as in any preceding claim is provided wherein a center of the measurement portion is positioned less than or equal to 2 mm from a center of a portion of the container positioned vertically beneath the probe.

[0028] In some embodiments, a method or article as in any preceding claim is provided wherein the measurement portion comprises a cone projecting vertically upwards.

[0029] In some embodiments, a method or article as in any preceding claim is provided wherein the measurement portion comprises a cone projecting vertically downwards.

[0030] In some embodiments, a method or article as in any preceding claim is provided wherein the cone has an angle to the vertical of greater than or equal to 5°.

[0031] In some embodiments, a method or article as in any preceding claim is provided wherein the measurement portion comprises a plurality of sawteeth.

[0032] In some embodiments, a method or article as in any preceding claim is provided wherein an angle between the hypotenuse of the sawteeth and the horizontal direction is greater than or equal to 5° and less than or equal to 45°.

[0033] In some embodiments, a method or article as in any preceding claim is provided wherein an external surface of a bottom of the container is flat.

[0034] In some embodiments, a method or article as in any preceding claim is provided wherein an internal surface of a bottom of the container has a surface roughness of less than or equal to 0.7 Ra.

[0035] In some embodiments, a method or article as in any preceding claim is provided wherein an internal surface of a bottom of the container has a surface roughness of less than or equal to 1 Ra.

[0036] In some embodiments, a method or article as in any preceding claim is provided wherein the bottom of the container is opaque.

[0037] In some embodiments, a method or article as in any preceding claim is provided wherein the container comprises a plastic. In some embodiments, a method or article as in any preceding claim is provided wherein the optical signal is detected while an article in which the container is positioned is tilted at an angle of less than or equal to 45°.

[0038] In some embodiments, a method or article as in any preceding claim is provided wherein the measurement portion is flat.

[0039] Other advantages and novel features of the present invention will become apparent from the following detailed description of various non-limiting embodiments of the invention when considered in conjunction with the accompanying figures. In cases where the present specification and a document incorporated by reference include conflicting and / or inconsistent disclosure, the present specification shall control. If two or more documents incorporated by reference include conflicting and / or inconsistent disclosure with respect to each other, then the document having the later effective date shall control.

[0040] BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Non-limiting embodiments of the present invention will be described by way of example with reference to the accompanying figures, which are schematic and are not intended to be drawn to scale. In the figures, each identical or nearly identical component illustrated is typically represented by a single numeral. For purposes of clarity, not every component is labeled in every figure, nor is every component of each embodiment of the invention shown where illustration is not necessary to allow those of ordinary skill in the art to understand the invention. In the figures:

[0042] FIG. 1 shows one non-limiting example of a container for a fluid in accordance, in accordance with some embodiments;

[0043] FIG. 2A shows one non-limiting example of an article, in accordance with some embodiments;

[0044] FIG. 2B shows another non-limiting example of an article comprising a plurality of containers, in accordance with some embodiments;

[0045] FIG. 3 shows one example of a method, in accordance with some embodiments;

[0046] FIG. 4 shows one non-limiting example of a cross-section of a cone that projects vertically upwards and is positioned in a measurement portion, in accordance with some embodiments; FIG. 5 shows one non-limiting example of a cross-section of a cone that projects vertically downwards and is positioned in a measurement portion, in accordance with some embodiments;

[0047] FIG. 6 shows one non-limiting example of a cross-section of a measurement portion comprising sawteeth, in accordance with some embodiments;

[0048] FIG. 7 shows various container designs, in accordance with some embodiments;

[0049] FIG. 8 shows the angle of reflection of a light ray impinging on a measurement portion, in accordance with some embodiments;

[0050] FIG. 9 shows scattering produced by an exemplary rough coating, in accordance with some embodiments;

[0051] FIGs. 10 and 11 show containers comprising coatings, in accordance with some embodiments;

[0052] FIG. 12 depicts schematically one example of a process by which an optical signal comprising both an amount of the light that has been reflected from an interface internal to a probe and an amount of light that has been reflected from the end of a first probe can be generated, in accordance with some embodiments;

[0053] FIG. 13 shows one non-limiting embodiment of a probe, in accordance with some embodiments;

[0054] FIG. 14 shows another non-limiting example of a probe, in accordance with some embodiments;

[0055] FIG. 15 shows one non-limiting example of an article comprising a plurality of containers for fluids, in accordance with some embodiments;

[0056] FIGs. 16-22 show the reflection of light from measurement portions comprising a cone (FIGs. 16, 18, 19, 20, and 22) and a plurality of sawteeth (FIGs. 17 and 21), in accordance with some embodiments;

[0057] FIGs. 23-26 show various mechanical drawings of one non-limiting example of an article comprising a plurality of containers for fluids, in accordance with some embodiments;

[0058] FIGs. 27 and 28 show two examples of containers for fluids comprising a single lightabsorbing coating disposed on a substrate, in accordance with some embodiments;

[0059] FIGs. 29 and 30 show two examples of containers for fluids comprising a first lightabsorbing coating disposed on a substrate and a second coating that is not light-absorbing disposed on the first coating, in accordance with some embodiments;

[0060] FIG. 31 shows a further example of a container for a fluid comprising a lightabsorbing coating, in accordance with some embodiments; and FIGs. 32 and 33 show experimental data, in accordance with some embodiments.

[0061] DETAILED DESCRIPTION

[0062] Articles comprising containers for fluid and methods of performing optical measurements on fluids contained in such articles are generally described herein. Some articles described herein may have a design such that light supplied during the performance of an optical measurement, such as during an optical assay, is mostly or entirely directed away from the probe that supplies it. This may allow for light that is generated during the assay, such as light associated with an experimental measurement or a positive control, to make up a relatively high percentage (or all) of the light incident on the probe. Advantageously, this property may reduce the amount of background noise present in the optical measurement and / or may facilitate the performance and analysis of optical measurements for which the signal is relatively low.

[0063] In some embodiments, an article comprises a container for a fluid that comprises a measurement portion including one or more features that assist with directing light away from a probe that supplies it. The measurement portion may be positioned beneath a component of an instrument designed to supply light to the fluid in the container during performance of the optical measurement (e.g., a probe), and / or may be capable of being and / or configured to be so positioned. In some embodiments, a measurement portion comprises topographical features that cause light incident on the measurement portion (e.g., perpendicular to the article, vertically downwards) to reflect in a direction other than back towards the source of the light (i.e., at an angle other than 180° with respect to the angle of incidence). Such features may include one or more portions of the bottom of the container that are angled such that light incident thereon at an angle close to 0° with respect to the article as a whole and / or the vertical (e.g., perpendicular to the article, vertically downwards) is incident with respect to those portions at an angle of other than 0°. Such light may be reflected of those portions at an angle of reflection that is thus greater than 0°. In some instances, the angle of reflection may be high enough such that a probe supplying the light is not in its optical pathway.

[0064] In some embodiments, the measurement portion of a container comprises one or more features that facilitate the direction of light away from a probe while the article as a whole is relatively untilted. Similarly, a method may comprise performing an optical measurement while an article and / or a container is relatively untilted. This may facilitate the performance of an assay under conditions in which the container is filled to a relatively high degree, as tilting an article and / or a container may cause fluid to spill if the container is relatively full.

[0065] In some embodiments, a measurement portion exhibits a relatively low level of height variation. Advantageously, this may facilitate the presence of a relatively uniform amount of fluid in the optical pathway during the performance of an optical measurement.

[0066] In some embodiments, a container described herein can be particularly suitable for preventing and / or reducing the presence of aliased signals. Without wishing to be bound by any particular theory, aliasing may undesirably occur when surface defects in a measurement portion of a container (e.g., sink marks, flow lines, scratches, uneven surface roughness, and / or flash) cause reflection from the container that is not spatially uniform and a measurement is performed while the container and / or a probe is being translated (e.g., along an orbital pathway). The variation in the reflection caused by such defects and their non- uniform position with respect to the probe may cause light to be reflected back into the probe in a manner that varies over time. If signal is sampled at a rate insufficient to capture these variations in reflected light accurately, it may result in the presence of noise that makes it challenging to differentiate various signals from each other and / or may result in the presence of a false and / or aliased signal. Some designs described herein may have geometries that reduce reflection back into a probe even from measurement portions including surface defects, desirably reducing aliasing.

[0067] FIG. 1 shows one non-limiting example of a container for a fluid in accordance with some embodiments described herein. In FIG. 1, the container 100 comprises a measurement portion 102 that makes up a portion of the bottom 104 of the container. In some embodiments, some or all of a measurement portion is positioned beneath a probe when an optical measurement is being performed. It is also possible for a measurement portion to be configured to be and / or capable of being so positioned. Similarly, in some embodiments, some or all of the portion of the container positioned beneath a probe when an optical measurement is being performed is part of the measurement portion.

[0068] In some embodiments, a measurement portion has a larger spatial extent than the portion of the bottom of the container positioned beneath the probe. Such designs may be beneficial for making optical measurements during which shaking is performed, as the portions of the container that are positioned beneath the probe may change during shaking. If the spatial extent of the measurement portion is large enough such that some part of the measurement portion remains positioned beneath the probe during such shaking (e.g., such that the portion positioned beneath the probe is made up in whole or in part by the measurement portion), it may facilitate the performance of optical measurements during such shaking.

[0069] In some embodiments, like the embodiment shown in FIG. 1, a measurement portion may be positioned in the center of the bottom of the container. It is also possible for a measurement portion to be positioned off center. Similarly, although the measurement portion shown in FIG. 1 is flat, in many instances, a measurement portion comprises one or more angled surfaces and / or exhibits topography.

[0070] In some embodiments, an article comprises one or more containers for fluids. As one example, in some embodiments, an article comprises one or more containers for fluids having some or all of the features shown in FIG. 1. FIG. 2A shows one non-limiting example of such an article. In FIG. 2A, the article 206 comprises a plurality of containers, of which container 200 is one example. In some embodiments, some or all of the containers in an article comprise a measurement portion having one or more of the features described herein. FIG. 2B shows another non-limiting example of an article comprising a plurality of containers.

[0071] It should also be noted that, like FIG. 1, FIGs. 2A and B are merely schematic and articles contemplated herein may be identical to that shown in FIG. 2A or FIG. 2B or may have one or more differences from such articles. As one example, in some embodiments, like the embodiments shown in FIGs. 2A and 2B, a container for a fluid may take the form of a well in the article. For instance, some articles may comprise a different number of containers for fluids (e.g., exactly one, more than one but fewer than those shown in FIG. 2A or FIG. 2B, more than those shown in FIG. 2A or FIG. 2B). Some articles may include containers having different shapes and / or arranged in a different manner than shown in FIG. 2A or FIG. 2B. Some articles may have a different design for the non-container portions than the articles shown in FIG. 2A and FIG. 2B (e.g., they may lack the letters and notch shown in FIG. 2A, they may have a different design for the upper surface) and / or have a different overall shape than shown in FIG. 2A or FIG. 2B (e.g., they may be rectangular but have a different aspect ratio than shown in FIGs. 2A and 2B, they may be non-rectangular).

[0072] In some embodiments, a method is provided. One example of a method is shown in FIG. 3. As shown in FIG. 3, a method may comprise transmitting light through an end of a probe to a fluid positioned in a container (step 308 in FIG. 3). Such a method may further comprise detecting an optical signal based on the interaction of the light with one or more species present in the fluid and / or immobilized on the probe (step 310 in FIG. 3). In some embodiments, a container employed in a method described herein (e.g., the container referred to in FIG. 3) may be positioned in an article described herein and / or may have one or more features of the containers for fluids described herein (e.g., the article shown in FIG. 2A, the container shown in FIG. 1). In some embodiments, the article in which the container is positioned is tilted at a relatively low angle.

[0073] In some embodiments, a measurement portion of a container is positioned beneath a probe while the light is transmitted through the end of the probe and / or while the optical signal is detected. In some embodiments, a measurement portion of a container is illuminated by the probe (e.g., during optical signal detection). It is also possible for a measurement portion to be configured to be and / or capable of being so positioned. Similarly, in some embodiments, some or all of the portion of the container illuminated by the probe is part of the measurement portion. In some embodiments, a measurement portion has a larger spatial extent or surface area than that of the portion of the bottom of the container illuminated by the probe. The illumination may occur after being transmitted through one or more materials (e.g., fluid contained in the container). In some embodiments, the light illuminating the measurement portion has not been reflected after leaving the probe.

[0074] Measurement portions described herein may have a variety of suitable designs. In some embodiments, a measurement portion comprises one or more features that direct light away from a probe from which it was supplied. As one example, in some embodiments, a measurement portion comprises a cone and / or a portion of a cone. For instance, a container may comprise a cone that is partially positioned in the measurement portion thereof and partially extends beyond the measurement portion thereof. In some embodiments, a measurement portion consists of a cone or a portion of a cone and / or consists essentially of a cone or a portion of a cone. It is also possible for a measurement portion to comprise a cone and one or more further features.

[0075] When present, a cone may project vertically upwards or vertically downwards (e.g., from the bottom of the container in which the measurement portion is positioned). Cones that project vertically upwards may project in a direction 180° from gravity when the article in which the measurement portion is positioned is untilted. As used herein, an article is untilted when it has an orientation that is equivalent to the orientation it would have if it were positioned to be stably resting on a flat surface perpendicular to the vertical direction (e.g., a flat surface that is perpendicular to gravity, such as an air table positioned on the floor of a room and / or a flat surface that a level measuring tool would indicate is level) and the container(s) for the fluid therein were oriented such that the measurement portion would be positioned on the bottoms of the containers. Cones that project vertically downwards may project in the direction of gravity when the article is so positioned.

[0076] As used herein, when used with respect to a direction, the words and phrases “vertical,” “vertical direction,” and “vertical axis” may be used interchangeably.

[0077] FIG. 4 shows one non-limiting example of a cross-section of a cone that projects vertically upwards and is positioned in a measurement portion. In FIG. 4, the cone 412 projects vertically upwards from the bottom of the container 404 at an angle of 414 to the vertical (and / or with respect to a vertical axis). The vertical / vertical axis in FIG. 4 is shown by the dashed line. FIG. 5 shows one non-limiting example of a cross-section of a cone that projects vertically downwards and is positioned in a measurement portion. In FIG. 5, the cone 516 projects vertically upwards from the bottom of the container 504 at an angle of 518 to the vertical (and / or with respect to a vertical axis). The vertical / vertical axis in FIG. 5 is also shown by the dashed line.

[0078] It is also possible for a measurement portion to comprise two or more cones (not shown). In such embodiments, the cones may all project in the same direction or may comprise some cones that project vertically upwards and some cones that project vertically downwards.

[0079] When present, cones may have a variety of angles. In some embodiments, a cone has an angle to the vertical and / or with respect to a vertical axis that is greater than or equal to 5°, greater than or equal to 10°, greater than or equal to 15°, greater than or equal to 20°, greater than or equal to 25°, greater than or equal to 30°, greater than or equal to 40°, greater than or equal to 50°, greater than or equal to 55°, greater than or equal to 60°, greater than or equal to 65°, greater than or equal to 70°, greater than or equal to 75°, greater than or equal to 80°, or greater than or equal to 85°. In some embodiments, a cone has an angle to the vertical and / or with respect to a vertical axis of less than 90°, less than or equal to 85°, less than or equal to 80°, less than or equal to 75°, less than or equal to 70°, less than or equal to 65°, less than or equal to 60°, less than or equal to 55°, less than or equal to 50°, less than or equal to 45°, less than or equal to 40°, less than or equal to 35°, less than or equal to 30°, less than or equal to 25°, less than or equal to 20°, less than or equal to 15°, or less than or equal to 10°. Combinations of the above-referenced ranges are also possible (e.g., greater than or equal to 5° and less than 90°). Other ranges are also possible.

[0080] In a measurement portion comprising more than one cone, each such cone’s angle may independently satisfy one or more of the above-described ranges and / or one or more of the above-described ranges may characterize the average angle of all such cones. Similarly, when an article comprises more than one container, each container may independently comprise a cone having an angle in one or more of the above-described ranges and / or a plurality of cones having an average angle in one or more of the above-described ranges. In some embodiments, all of the cones in an article together have an average angle in one or more of the above-described ranges.

[0081] In some embodiments, a measurement portion comprises a plurality of sawteeth. FIG. 6 shows one non-limiting example of a cross-section of a measurement portion comprising such sawteeth. In some embodiments, a measurement portion consists of a plurality of sawteeth and / or consists essentially of a plurality of sawteeth. It is also possible for a measurement portion to comprise a plurality of sawteeth and one or more further features (e.g., a cone and / or a portion of a cone). In FIG. 6, the container 600 comprises a plurality of sawteeth 620 that extend upwards from the bottom 604. The angle between the angle between the hypotenuse of the sawteeth and the horizontal direction is shown by angle 622 in this FIG. The horizontal direction for the purpose of the angle 622 is the direction perpendicular to the periodicity of the sawteeth in the plane perpendicular to gravity when the article in which the measurement portion is positioned is untilted.

[0082] Sawteeth may have a variety of angles between their hypotenuses and the horizontal direction. In some embodiments, the angle between a sawtooth and the horizontal direction is greater than or equal to 5°, greater than or equal to 10°, greater than or equal to 15°, greater than or equal to 20°, greater than or equal to 25°, greater than or equal to 30°, greater than or equal to 35°, or greater than or equal to 40°. In some embodiments, the angle between a sawtooth and the horizontal direction is less than or equal to 45°, less than or equal to 40°, less than or equal to 35°, less than or equal to 30°, less than or equal to 25°, less than or equal to 20°, less than or equal to 15°, or less than or equal to 10°. Combinations of the abovereferenced ranges are also possible (e.g., greater than or equal to 5° and less than or equal to 45°). Other ranges are also possible.

[0083] In a measurement portion comprising more than one sawtooth (e.g., a plurality of sawteeth), each such sawtooth’s angle with respect to the horizontal direction may independently satisfy one or more of the above-described ranges and / or one or more of the above-described ranges may characterize the average angle with respect to the horizontal direction of all such sawteeth. Similarly, when an article comprises more than one container, each container may independently comprise a sawtooth having an angle with respect to the horizontal direction in one or more of the above-described ranges and / or a plurality of sawteeth having an average angle with respect to the horizontal direction in one or more of the above-described ranges. In some embodiments, all of the sawteeth in an article together have an average angle with respect to the horizontal direction in one or more of the abovedescribed ranges.

[0084] Further examples of suitable designs for measurement portions are shown in FIG. 7. FIG. 7 shows containers having measurement portions that, from left to right, comprise a cone that projects vertically downwards, a plurality of sawteeth, a cone that projects vertically upwards, a slant, a coating, and a rough surface.

[0085] In some embodiments, a container for a fluid and / or a measurement portion thereof has a geometry such that a relatively low amount of light supplied by a probe (e.g., transmitted through an end thereof) is reflected from the container into the end of the probe (e.g., during detection of an optical signal generated in fluid contained in a container in which the measurement portion is positioned). In some embodiments, less than or equal to 50%, less than or equal to 45%, less than or equal to 40%, less than or equal to 35%, less than or equal to 30%, less than or equal to 25%, less than or equal to 20%, less than or equal to 15%, less than or equal to 10%, less than or equal to 5%, less than or equal to 2%, or less than or equal to 1% of light supplied by a probe is reflected from the container into the end of the probe. In some embodiments, greater than or equal to 0% of light supplied by a probe is reflected from the container into the end of the probe. Combinations of the above-referenced ranges are also possible (e.g., less than or equal to 50% and greater than or equal to 0%). Other ranges are also possible.

[0086] In an article comprising more than one container for a fluid, each such container may independently satisfy one or more of the above-described ranges and / or one or more of the above-described ranges may characterize the average reflection by all of the containers for the fluid.

[0087] It should also be noted that light supplied by a probe may impinge vertically on a container for a fluid and / or a measurement portion or may impinge at angle other than the vertical (e.g., at an angle close to the vertical). It is also possible for a probe to supply light that impinges on a container for a fluid and / or a measurement portion over a range of angles (e.g., a range of angles for which 0° with respect to the vertical is the median, mode, and / or mean angle; a range of angles having a relatively small angular spread).

[0088] In some embodiments, a container for a fluid and / or a measurement portion thereof has a geometry such that a relatively low amount of light impinging vertically thereon (e.g., transmitted through an end of a probe thereto) is reflected from the container at a relatively low angle. In some embodiments, less than or equal to 50%, less than or equal to 45%, less than or equal to 40%, less than or equal to 35%, less than or equal to 30%, less than or equal to 25%, less than or equal to 20%, less than or equal to 15%, less than or equal to 10%, less than or equal to 5%, less than or equal to 2%, or less than or equal to 1% of light impinging vertically on a measurement portion and / or a container is reflected at an angle of less than or equal to 18° (and / or less than or equal to 35°) to the vertical and / or with respect to a vertical axis. In some embodiments, greater than or equal to 0% of light impinging vertically on a measurement portion and / or a container is reflected at an angle of less than or equal to 18° (and / or less than or equal to 35°) to the vertical and / or with respect to a vertical axis. Combinations of the above-referenced ranges are also possible (e.g., less than or equal to 50% and greater than or equal to 0%). Other ranges are also possible.

[0089] In some embodiments, a container for a fluid and / or a measurement portion thereof has a geometry such that a relatively low amount of light impinging vertically thereon (e.g., transmitted through an end of a probe thereto) is reflected from the container at a relatively low angle when the article in which it is positioned is untilted. In some embodiments, less than or equal to 50%, less than or equal to 45%, less than or equal to 40%, less than or equal to 35%, less than or equal to 30%, less than or equal to 25%, less than or equal to 20%, less than or equal to 15%, less than or equal to 10%, less than or equal to 5%, less than or equal to 2%, or less than or equal to 1% of light impinging vertically on a measurement portion and / or a container is reflected at an angle of less than or equal to 18° (and / or less than or equal to 35°) to the vertical and / or with respect to a vertical axis when the article in which the container and / or measurement portion is positioned is untilted. In some embodiments, greater than or equal to 0% of light impinging vertically on a measurement portion and / or a container is reflected at an angle of less than or equal to 18° (and / or less than or equal to 35°) to the vertical and / or with respect to a vertical axis when the article in which the container and / or measurement portion is positioned is untilted. Combinations of the above-referenced ranges are also possible (e.g., less than or equal to 50% and greater than or equal to 0%). Other ranges are also possible.

[0090] It is also possible for a container for a fluid and / or a measurement portion thereof to have a geometry such that an amount of light impinging vertically thereon is reflected at an angle in one or more of the above-referenced ranges when the when the article in which the container and / or measurement portion is positioned is tilted at one or more angles and / or has an unknown tilt.

[0091] The angle to the vertical at which a light ray impinging vertically on a measurement portion is reflected can be appreciated from FIG. 8. In FIG. 8, the light ray 824 impinging vertically on the measurement portion 802 of the container 800 is reflected in ray 826 at an angle 828 to the vertical and to a vertical axis (e.g., vertical light ray 824). As show in this exemplary embodiment, the angles (and verticals) are measured when the article in which the container and / or measurement portion is positioned is untilted. As also shown in this exemplary embodiment, because the light ray 824 impinges vertically, it is collinear with the vertical and the vertical axis. As also shown in FIG. 8, the container 800 has a bottom 804.

[0092] In an article comprising more than one container for a fluid, each such container’ s measurement portion may independently satisfy one or more of the above-described ranges, one or more of the above-described ranges may characterize the angle of reflection of all of such containers’ measurement portions, and / or one or more of the above-described ranges may characterize the angle of reflection of all such containers.

[0093] In some embodiments, a measurement portion has a relatively low variation in height. The variation in height may be less than or equal to 1.75 mm, less than or equal to 1.6 mm, less than or equal to 1.5 mm, less than or equal to 1.25 mm, less than or equal to 1 mm, less than or equal to 0.75 mm, less than or equal to 0.5 mm, less than or equal to 0.25 mm, or less than or equal to 0.1 mm. The variation in height may be greater than or equal to 0 mm. Combinations of the above-referenced ranges are also possible (e.g., less than or equal to 1.75 mm and greater than or equal to 0 mm, or less than or equal to 1.6 mm and greater than or equal to 0 mm). Other ranges are also possible.

[0094] As used herein, the height variation refers to the difference in height in the vertical direction between the lowest point on the measurement portion and the highest point on the measurement portion when the article is untilted. The height variation is shown by the letter “h” in FIGs. 4-6.

[0095] In an article comprising more than one container for a fluid, each such container’ s measurement portion may independently satisfy one or more of the above-described ranges and / or one or more of the above-described ranges may characterize the average height variation of all of such containers’ measurement portions.

[0096] The diameter of the measurement portion may be selected as desired. In some embodiments, the diameter of the measurement portion is approximately half of the diameter of the area enclosed by the opening of the container for a fluid in which it is positioned. For instance, the diameter of the measurement portion may be greater than or equal to 33%, greater than or equal to 35%, greater than or equal to 40%, greater than or equal to 45%, greater than or equal to 50%, greater than or equal to 55%, or greater than or equal to 60% of the diameter of the area enclosed by the opening of the container for a fluid in which it is positioned. In some embodiments, the diameter of the measurement portion is less than or equal to 66%, less than or equal to 60%, less than or equal to 55%, less than or equal to 50%, less than or equal to 45%, less than or equal to 40%, or less than or equal to 35% of the diameter of the area enclosed by the opening of the container for a fluid in which it is positioned. Combinations of the above-referenced ranges are also possible (e.g., greater than or equal to 33% and less than or equal to 66%). Other ranges are also possible.

[0097] The diameter of a measurement portion may be determined by measuring the surface area of the measurement portion and then finding the diameter of a circle that has the same area.

[0098] In an article comprising more than one container for a fluid, each such container’ s measurement portion may independently satisfy one or more of the above-described ranges and / or one or more of the above-described ranges may characterize the average diameter of all of such containers’ measurement portions.

[0099] In some embodiments, the diameter of the measurement portion of a container for a fluid is greater than or equal to 2.25 mm, greater than or equal to 2.5 mm, greater than or equal to 2.75 mm, greater than or equal to 3 mm, greater than or equal to 3.25 mm, greater than or equal to 3.5 mm, greater than or equal to 3.75 mm, or greater than or equal to 4 mm. In some embodiments, the diameter of the measurement portion of a container for a fluid is less than or equal to 4.25 mm, less than or equal to 4 mm, less than or equal to 3.75 mm, less than or equal to 3.5 mm, less than or equal to 3.25 mm, less than or equal to 3 mm, less than or equal to 2.75 mm, or less than or equal to 2.5 mm. Combinations of the above-referenced ranges are also possible (e.g., greater than or equal to 2.25 mm and less than or equal to 4.25 mm. Other ranges are also possible.

[0100] In an article comprising more than one container for a fluid, each such container’ s measurement portion may independently satisfy one or more of the above-described ranges and / or one or more of the above-described ranges may characterize the average diameter of all of such containers’ measurement portions.

[0101] As noted above, a measurement portion positioned in a container for a fluid may be positioned partially or fully beneath a probe. In some embodiments, the center of the measurement portion may be positioned relatively closely to the center of the portion of the container positioned beneath the probe. For instance, the distance between the center of the measurement portion and the center of the portion of the container positioned beneath the probe may be less than or equal to 2 mm, less than or equal to 1.5 mm, less than or equal to 1 mm, less than or equal to 0.75 mm, less than or equal to 0.5 mm, less than or equal to 0.25 mm, or less than or equal to 0.1 mm. In some embodiments, the distance between the center of the measurement portion and the center of the portion of the container positioned beneath the probe is greater than or equal to 0 mm. Combinations of the above-referenced ranges are also possible (e.g., less than or equal to 2 mm and greater than or equal to 0 mm, or less than or equal to 1 mm and greater than or equal to 0 mm). Other ranges are also possible.

[0102] In an article comprising more than one container for a fluid, each such container’ s measurement portion may independently satisfy one or more of the above-described ranges and / or one or more of the above-described ranges may characterize the average distance between the centers of all of such containers’ measurement portions and the centers of the portion of the containers for the fluid positioned beneath the probe. Similarly, the abovedescribed ranges may characterize the measurement portion at a single timepoint and / or may characterize the measurement portion over a period of time (e.g., during shaking). In some embodiments, the above-described ranges characterize the average distance between the centers of all of such containers’ measurement portions and the centers of the portion of the containers for the fluid positioned beneath the probe over a period of time (e.g., during shaking).

[0103] In some embodiments, a container for a fluid comprises an external surface and an internal surface. The external surface may be positioned on the side of the bottom of the container opposite the side that contacts fluid positioned therein (and / or is capable of contacting and / or configured to contact such fluid). The external surface of the container 100 in FIG. 1 is shown by reference sign 104A and the internal surface of this container is shown by reference sign 104B. In some embodiments, an external surface of a container is flat. Without wishing to be bound by any particular theory, it is believed that the presence of a flat external surface on a container bottom may facilitate the heating and / or cooling of the container and / or fluid contained therein. A surface that is flat may exhibit better contact with a heating or cooling element than a surface that is not flat, and so it may be easier to achieve a higher degree of thermal contact with flat surfaces.

[0104] In some embodiments, a bottom of a container for a fluid has an external surface that is flat and further comprises one or more of the topological features described herein (e.g., a cone, a plurality of sawteeth). In such embodiments, these topological features may be positioned on the internal surface of the bottom of the container and / or extend upwards and / or downwards from an internal surface of the bottom of the container.

[0105] It is also possible for an internal surface of a bottom of a container for a fluid to be flat. For instance, as described in further detail below, in some embodiments, an internal surface of a bottom of a container for a fluid has one or more features other than topological features that reduce undesirable reflection. Such features may take the form of surface roughness and / or coatings having particular properties as described in further detail below. Of course, it is also possible for an internal surface of a bottom of a container to comprise one or more topological features described herein (e.g., a cone, a plurality of sawteeth) and further have a surface roughness in a range described herein and / or comprise a coating described herein.

[0106] In some embodiments, an internal surface of a bottom of a container for a fluid has a relatively low surface roughness. It is also possible for an internal surface of a bottom of a container for a fluid to have a surface roughness that facilitates the random (or bulk) scattering of light. Without wishing to be bound by any particular theory, it is believed that light impinging on a rough surface (e.g., a micro-rough surface) may scatter randomly. This random scattering may be instead of specular reflection that would otherwise reflect the impinging light directly back to its source, and may thereby advantageously reduce the amount of light reflected from the measurement portion back to a light source. The scattering produced by an exemplary rough coating is shown schematically in FIG. 9.

[0107] In some embodiments, an internal surface of a container has a surface roughness of less than or equal to 1 Ra, less than or equal to 0.7 Ra, less than or equal to 0.5 Ra, less than or equal to 0.25 Ra, less than or equal to 0.2 Ra, or less than or equal to 0.1 Ra. In some embodiments, an internal surface of a container has a surface roughness of greater than or equal to 0 Ra, greater than or equal to 0.1 Ra, greater than or equal to 0.2 Ra, greater than or equal to 0.25 Ra, or greater than or equal to 0.25 Ra. Combinations of the above-referenced ranges are also possible (e.g., less than or equal to 1 Ra and greater than or equal to 0 Ra, less than or equal to 0.7 Ra and greater than or equal to 0 Ra, or less than or equal to 1 Ra and greater than or equal to 0.2 Ra,). Other ranges are also possible. In some embodiments, an internal surface of a bottom of a container for a fluid is micro-rough (e.g., it may have micron-scale roughness).

[0108] Ra may be determined in microns.

[0109] In an article comprising more than one container for a fluid, each such container’ s bottom internal surface may independently satisfy one or more of the above-described ranges and / or one or more of the above-described ranges may characterize the average surface roughness of all of such containers’ bottom internal surfaces.

[0110] As noted above, in some embodiments, a container for a fluid is positioned in an article comprising a plurality of containers. Such containers may be identical to each other or may differ in one or more ways. In some embodiments, an article described herein is a multiwell plate and the containers therein are wells in the multi-well plate.

[0111] Containers and the articles in which they are positioned may have a variety of suitable visual appearances. In some embodiments, a container has an opaque bottom. The internal surface of the bottom and / or the external surface of the bottom may be opaque. The opacity may be with respect to the visual range (e.g., such container bottoms may appear black to the naked eye) and / or to one or more wavelengths supplied by a probe during an optical measurement.

[0112] Containers and the articles in which they are positioned may have a variety of suitable compositions. In some embodiments, a container and / or an article in which a container is positioned comprises a plastic, consists of a plastic, and / or consists essentially of a plastic. Without wishing to be bound by any particular theory, it is believed that the use of plastic in containers and articles in which they are positioned advantageously facilitates the use of molding manufacturing.

[0113] In some embodiments, a container comprises two or more components. As an example, in some embodiments, a container comprises a substrate (e.g., a substrate having a composition described in the preceding paragraph) and one or more coatings disposed on the substrate. In some embodiments, a surface of a coating opposite the substrate may form some or all of the internal surface of the bottom of the container. Similarly, a coating may be disposed across the entirety of the substrate and / or may be disposed only on one or more portions of the substrate (e.g., it may be positioned exclusively in the bottom of the container, and / or it may solely occupy a measurement portion of the container).

[0114] FIG. 10 shows one non-limiting example of a container 1000 comprising a coating 1040 disposed on a substrate 1042. In FIG. 10, the substrate extends throughout the entirety of the container, and the coating is positioned only on the bottom of the container. At the bottom of the container, the coating is positioned between the interior of the container and the substrate.

[0115] It is also possible for a container to comprise two or more coatings. FIG. 11 shows one non-limiting example of such a container. In FIG. 11, the container 1100 comprises a first coating 1140, a second coating 1144 disposed on the first coating, and a substrate 1142. In the embodiment shown in FIG. 11, the first and second coatings both occupy the same area (i.e., the entirety of the bottom of the container) and the second coating entirely covers the first coating. However, other arrangements are also possible. For instance, the second coating may partially cover the first coating, extend beyond the first coating, or be non- overlapping with the first coating. As another example, in some embodiments, a second coating and a first coating interpenetrate. In some such embodiments, a first coating may have a relatively rough surface and / or may comprise one or more pores and the second coating may (in addition to or as an alternative to being disposed on a side of the first coating opposite the substrate) penetrate into one or more surface features and / or pores of the first coating (and / or all the way through a network of pores present in the first coating).

[0116] In some embodiments, a container comprises a coating that assists with reducing the amount of light reflected from the container into the probe. For instance, a container may comprise a coating that is light- absorbing. Such coatings may comprise one or more lightabsorbing components (e.g., in the presence of one or more additional components that facilitate coating formation and / or that compatibilize the light- absorbing components with a substrate on which the coating is disposed and / or with fluids that may be positioned in the containers). It is also possible for such coatings to consist of and / or consist essentially of light-absorbing components.

[0117] In some embodiments, a container comprises a light-absorbing coating and a coating that is not light-absorbing. In some such embodiments, the coating that is not light-absorbing may be disposed on the coating that is light-absorbing (e.g., on a surface of the lightabsorbing coating opposite a substrate on which the light- absorbing coating is disposed). When present, a coating that is not light- absorbing may be a compatibilizing coating. Compatibilizing coatings may serve to chemically compatibilize a coating that is lightabsorbing with a fluid to be contained in the container and / or may assist with reducing the amount of light reflected from a light-absorbing coating. As one example of the former property, in some embodiments, a coating that is not light- absorbing may be positioned between an environment internal to the container and a light-absorbing coating that is undesirably reactive with one or more components of a fluid to be positioned in the container. As one example of the latter, in some embodiments, a coating that is not light-absorbing is disposed on a coating that is light-absorbing and has a surface with a topography that would result in undesirable reflection of light that does not get absorbed thereby. The coating that is not light- absorbing may penetrate into this surface topography of the light- absorbing coating and present a surface facing the interior of the container (e.g., an interior surface) that has a more favorable surface topography. This may result in reduced reflection of light impinging on the interior surface of the container.

[0118] In some embodiments, a light- absorbing coating comprises light- absorbing particles and a polymer. The light- absorbing particles may be dispersed in the polymer. In some embodiments, the polymer assists with the formation of a coating that is relatively spatially uniform and / or absorbs light in a manner that is relatively constant across the area of the coating and / or across a measurement portion of the container (e.g., such that any differences are not observable via the naked eye or via UV-vis measurements).

[0119] It is also possible for a coating that is not light- absorbing to comprise a polymer. In some embodiments, such coatings may consist and / or consist essentially of one or more polymers.

[0120] Polymers present in the coatings described herein (light- absorbing and not lightabsorbing) may be chemically compatible with one or more fluids to be positioned in the container. This chemical compatibility may comprise stability of the polymer in the fluid (e.g., the polymer may undergo minimal or no dissolution in the fluid, may absorb little or none of the fluid, may remain a solid upon contact with the fluid, and / or may undergo minimal or no reactions upon exposure to the fluid) and / or stability of the fluid upon contact with the polymer (e.g., the fluid may undergo minimal or no reactions upon exposure to the polymer, minimal or no components present in the fluid may precipitate from the fluid onto the polymer).

[0121] In some embodiments, a polymer present in a coating (light-absorbing or not lightabsorbing) has a refractive index that is relatively close to the refractive index of a fluid to be positioned in a container described herein. Advantageously, this may reduce and / or prevent reflection of light at the interface between the fluid and the coating. In some embodiments, a polymer present in a coating has a refractive index that is relatively close to 1.33. For instance, a coating may comprise a polymer having a refractive index of greater than or equal to 1.32 and / or less than or equal to 1.34.

[0122] In some embodiments, a polymer present in a coating (light-absorbing or not lightabsorbing) can be cured (and / or was cured) in a manner other than exposure to light. For instance, some such polymers may be moisture curable (and / or may be moisture-cured). Such a property may be desirable for coatings that further comprise light- absorbing particles. Light- absorbing particles may absorb light impinging on an uncured coating, preventing penetration of the light to lower portions of the coating and thus making full curing challenging. However, in some instances, moisture may be transported through a coating during curing and / or the uncured coating may be exposed to sufficient moisture during the coating deposition process to allow for polymers throughout the coating to be cured.

[0123] It is also possible for a container to comprise a polymer that can be cured (and / or was cured) upon exposure to light (e.g., UV light). Light-induced curing may be suitable for coatings that are not light-absorbing and / or that do not comprise an appreciable amount of light-absorbing components.

[0124] Coatings described herein may, in some embodiments, be cured in a manner that comprises performing one or more techniques to remove gases (e.g., air, gases in the form of bubbles, gases in the form of microbubbles) initially present in the uncured coating and / or generated during the curing process. This may be achieved by, for instance, applying a reduced pressure to the coating prior to, during, and / or after curing. Without wishing to be bound by any particular theory, it is believed that gases, bubbles, and microbubbles present in a coating may serve as locations that scatter light. Therefore, it is believed that the elimination of such gases, bubbles, and microbubbles may be desirable.

[0125] Polymers suitable for inclusion in the coatings described herein may have a variety of suitable viscosities. In some embodiments, a polymer has a viscosity of greater than or equal to 500 cP, greater than or equal to 750 cP, greater than or equal to 1000 cP, greater than or equal to 1500 cP, greater than or equal to 2000 cP, greater than or equal to 2500 cP, greater than or equal to 3000 cP, greater than or equal to 3500 cP, greater than or equal to 4000 cP, or greater than or equal to 4500 cP. In some embodiments, a polymer has a viscosity of less than or equal to 5000 cP, less than or equal to 4500 cP, less than or equal to 4000 cP, less than or equal to 3500 cP, less than or equal to 3000 cP, less than or equal to 2500 cP, less than or equal to 2000 cP, less than or equal to 1500 cP, less than or equal to 1000 cP, or less than or equal to 750 cP. Combinations of the above-referenced ranges are also possible (e.g., greater than or equal to 500 cP and less than or equal to 5000 cP). Other ranges are also possible.

[0126] When polymers and light-absorbing particles are present in a coating, they may be present in a variety of suitable ration. In some embodiments, a volume ratio of the lightabsorbing particles to the polymer is greater than or equal to 1:8, greater than or equal to 1:7, or greater than or equal to 1:6. In some embodiments, a volume ratio of the light- absorbing particles to the polymer is less than or equal to 1:5, less than or equal to 1:6, or less than or equal to 1:7. Combinations of the above-referenced ranges are also possible (e.g., greater than or equal to 1:8 and less than or equal to 1:5). Other ranges are also possible.

[0127] Without wishing to be bound by any particular theory, it is believed that volume ratios in excess of 1:5 may undesirably exhibit viscosities high enough to make them challenging to apply and that volume ratios of less than 1:8 may exhibit light absorptions that are undesirably low at the coating thicknesses described herein. Non-limiting examples of polymers suitable for use in the coatings described herein include MY-133-MC and BIO-133, both of which are available from MY Polymers LTD.

[0128] Non-limiting examples of particles suitable for use in the light-absorbing coatings described herein include carbon black (e.g., Smoke Black from Vallejo Pigments, Item 73116 from Vallejo Pigments) and black paint pigments. In some embodiments, a light-absorbing coating comprises microparticles.

[0129] Non-limiting examples of coatings comprising light- absorbing particles and a polymer include flat black paints (e.g., acrylic and / or water-based flat black paints, such as MUSOU black paint).

[0130] In some embodiments, a light- absorbing coating comprises a light-absorbing component other than a particle. Non-limiting examples of such components include black foils, such as Metal Velvet Black Foil, Lambertian Black Foil, and Spectral Black Foil (obtainable from Acktar). Light-absorbing coatings comprising components other than particles may lack polymers and / or may take the form of a first coating on which a second coating that is not light- absorbing is disposed.

[0131] In some embodiments, a container comprises an interference coating. When present, an interference coating may comprise one or more components that result in destructive interference. As one example, an interference coating may comprise a thin film of a material having a refractive index that is different from the refractive index of a fluid to be positioned in the container and / or different from the refractive index of a material on which the thin film is disposed or that is disposed on it (e.g., another thin film, a substrate, another coating). Light impinging upon the thin film from a material having a different refractive index may be partially reflected therefrom and may be partially transmitted therethrough. Light that is transmitted through the thin film may be partially reflected from the material on which the thin film is disposed. For certain thicknesses of these thin films, the light that is initially transmitted therethrough may undergo destructive interference with the light that is subsequently reflected from the material on which the thin film is disposed. This may reduce the overall amount of light reflected from the thin film.

[0132] In some embodiments, an interference coating includes exactly one thin film. It is also possible for an interference coating to include two or more thin films. In such instances, the various thin films present may have different thicknesses and / or refractive indices, which may result in the interference coating, as a whole, causing destructive interference of light at a variety of wavelengths. In some embodiments, a container comprises a moth-eye coating. When present, a moth-eye coating may have a nano structured surface that causes a gradual transition in the refractive index experienced by light impinging thereon. This gradual transition may occur across a pathway that extends from a fluid present in the container into the body of the coating. Without wishing to be bound by any particular theory, it is believed that abrupt changes in refractive index may cause reflection of light, but that gradual transitions in refractive index may cause less or no such reflection. In some embodiments, a moth-eye coating comprises nanostructures that are smaller than the wavelength of visible light, which may result in effective index matching, thereby reducing reflection.

[0133] Coatings described herein may have a variety of suitable thicknesses. In some embodiments, a coating has a thickness of greater than or equal to 1 mm and / or less than or equal to 2 mm. Without wishing to be bound by any particular theory, it is believed that, in some instances, thicker coatings may desirably reduce the volume that can be contained by the containers in which they are positioned. This may allow for the use of such containers with smaller volumes of fluid, which may be desirable when such containers are employed to contain fluids that are expensive, labor-intensive, and / or challenging to obtain.

[0134] As described above, some embodiments relate to methods. Such methods may comprise making an optical measurement, such as by transmitting light to a fluid and detecting an optical signal from a species present in the fluid and / or immobilized on a probe. In some embodiments, a method is performed while an article is shaking. This may be performed by translating the container along an orbital pathway. It is also possible for the article to be stationary during the performance of a method described herein (and / or during performance of a step of a method, such as detection of an optical signal). The probe may shake with the article, may shake separately from the article, or may be stationary during the performance of a method described herein (and / or a step thereof, such as detection of an optical signal).

[0135] When a container for a fluid is translated along an orbital pathway, the orbital pathway may be one such that a distance between a center of the measurement portion thereof and the center of the portion of the container positioned beneath the probe is kept relatively constant (e.g., where it varies by less than 5%, less than 2%, or less than 1% along the orbital pathway).

[0136] In an article comprising more than one container for a fluid, each such container’ s translation may independently satisfy one or more of the above-described ranges and / or one or more of the above-described ranges may characterize the average orbital pathway of all of such containers.

[0137] When a container for a fluid is translated along an orbital pathway, the center of the orbital pathway (i.e., axis perpendicular to and passing through the center of the ellipse or circle defined by orbital pathway) may be positioned at any distance from the axis along the center of the probe and / or may be parallel to the direction traveled by any light supplied by the probe. In some embodiments, the center of the orbital pathway is less than or equal to 0.5 mm, less than or equal to 0.45 mm, less than or equal to 0.4 mm, less than or equal to 0.35 mm, less than or equal to 0.3 mm, less than or equal to 0.25 mm, less than or equal to 0.2 mm, less than or equal to 0.15 mm, less than or equal to 0.1 mm, or less than or equal to 0.05 mm from the axis along the center of the probe. In some embodiments, the center of the orbital pathway is greater than or equal to 0 mm, greater than or equal to 0.05 mm, 0.1 mm, greater than or equal to 0.15 mm, greater than or equal to 0.2 mm, greater than or equal to 0.25 mm, greater than or equal to 0.3 mm, greater than or equal to 0.35 mm, greater than or equal to 0.4 mm, or greater than or equal to 0.45 mm from the axis along the center of the probe. Combinations of the above-referenced ranges are also possible (e.g., less than or equal to 0.5 mm and greater than or equal to 0 mm). Other ranges are also possible.

[0138] In an article comprising more than one container for a fluid, each such container’ s translation may independently satisfy one or more of the above-described ranges and / or one or more of the above-described ranges may characterize the average orbital pathway of all of such containers.

[0139] In some embodiments, a method and / or a step thereof (e.g., detecting an optical signal) is performed when an article comprising a container for a fluid is untilted and / or tilted at a low angle. The angle of tilt may be determined by determining the shortest angle of rotation that the article would need to pass through to achieve its untilted orientation. In some embodiments, a method and / or a step thereof is performed while the article is tilted at an angle of less than or equal to 45°, less than or equal to 40°, less than or equal to 35°, less than or equal to 30°, less than or equal to 25°, less than or equal to 20°, less than or equal to 15°, less than or equal to 10°, less than or equal to 5°, less than or equal to 2°, or less than or equal to 1°. In some embodiments, a method and / or a step thereof is performed while the article is tilted at an angle of greater than or equal to 0°, greater than or equal to 5°, greater than or equal to 10°, greater than or equal to 15°, greater than or equal to 20°, greater than or equal to 25°, greater than or equal to 30°, greater than or equal to 35°, or greater than or equal to 40°. Combinations of the above-referenced ranges are also possible (e.g., less than or equal to 45° and greater than or equal to 0°). Other ranges are also possible.

[0140] In some embodiments, a method comprises detecting an optical signal. Such an optical signal may be indicative of the presence, absence, and / or amount of a species immobilized on a probe. It is also possible for an optical signal to be indicative of the presence, absence, and / or amount of a species generated from a species immobilized on a probe. In some embodiments, an optical signal is indicative of a feature of a sample being analyzed and / or assayed (e.g., the presence, concentration, or absence of one or more components therein), indicative of a feature of a standard present in an assay (e.g., the presence, concentration, or absence of one or more components therein), a reference signal, a background signal, and / or a baseline signal.

[0141] An optical signal may comprise the presence or absence of light of a variety of wavelengths and / or polarizations. In some embodiments, the light may comprise visible light. It is also possible for the light to comprise infrared light. Additionally, the light may be polarized light or unpolarized light.

[0142] Optical signals may arise from a variety of locations in a fluid (e.g., a fluid with which a probe is and / or was in contact) and / or a solid (e.g., a solid surface of a probe, a solid surface of a layer disposed on a probe, a solid surface of a container of a fluid with which a probe is and / or was in contact). For instance, some optical signals may arise from a surface of a fluid or solid (e.g., an upper surface, a lower surface, a side surface). As another example, some optical signals may arise from an interior of a fluid or solid. In some embodiments, an optical signal arises from the entirety of the fluid or solid.

[0143] Optical signals may comprise light and / or the absence of light. The optical signal may comprise light that has interacted in some way with a species present in a fluid illuminated by light transmitted through a probe and / or with a species immobilized on a probe. Exemplary types of optical signals generated by such interactions are described in further detail below.

[0144] In some embodiments, a measurement comprises detecting an optical signal comprising both light reflected from an interface internal to a probe and light that has been reflected from the end of the probe. Such an optical signal may comprise both types of light, light interference between these two types of light (e.g., interference between light supplied by a common light source but traveling through optical pathways having different optical path lengths), the absence of either or both such type of light, and / or the absence of such interference. As two examples, optical signals may comprise interference between light that is reflected from two different interfaces associated with a probe and / or a species immobilized on a probe (e.g., an interface between an interior portion of a probe and a coating disposed on the internal portion of the probe, an interface between the species and the probe, an interface between the species and an environment external to the probe, an interface at the end of the probe) or the absence of such interference.

[0145] Light that is reflected from an interface may be supplied to a probe from a light source system. As described elsewhere herein, a light source system may be optically coupled to a probe such that light is transmitted from the light source system and across the probe (e.g., parallel to an optical axis of the probe). Upon reaching an end of the probe, the light may be transmitted out of the probe and / or may reflect from an interface between the probe and an environment external to the probe (and / or from the end of the probe). If there is a species immobilized on the probe, some light may reflect from the interface between the probe and the species and / or some light may be transmitted through the species. The species may also change the effective refractive index at the end of the probe and / or change the effective optical path length of the light transmitted through the probe. Light transmitted through the species will then encounter the environment with which the species is in contact (e.g., a fluid contacting the probe). Some light encountering this environment may be transmitted into the environment with which the species is in contact (e.g., an environment external to the probe) and / or may reflect from the interface between the environment and the species.

[0146] It is also possible for probe described herein to have one or more internal interfaces at which reflection may occur. For instance, some probes may comprise one or more internal interfaces at which reflection can occur, such as an interface between a coating and an interior portion of the probe on which the coating is disposed.

[0147] Light reflected from one or more of the above-described locations (and / or any further locations) may travel back through the probe. If light is reflected from multiple locations (e.g., at an interface between the probe and a species immobilized on the probe, at an interface between a species immobilized on the probe and an environment external to the probe, at an interface between a coating disposed on an interior portion of the probe and a species immobilized on the probe, at an interface between an interior portion of the probe and a coating disposed thereon, from the end of the probe), such light may interfere which each other. Light interference may cause the intensity of the interfered light to be higher or lower depending on whether the interference is positive or negative, which may depend on the phase shift between the multiple sources of interfering light. The phase shift may depend on the differences in the path lengths traveled by the light prior to interfering, the refractive index of the material(s) through which the light passes prior to interfering, and / or on the wavelength of light. Accordingly, obtaining information about the intensity of interfered light across a variety of wavelengths may provide information about the presence or absence of a layer comprising a species immobilized on a probe, the thickness of such a layer, and / or the refractive index of such a layer. This information may be employed to determine the presence, absence, and / or amount of the species immobilized on the probe.

[0148] FIG. 12 depicts schematically one example of a process by which an optical signal comprising both an amount of the light that has been reflected from an interface internal to a probe and an amount of light that has been reflected from the end of a first probe can be generated. As shown in FIG. 12, light that travels down a probe may reflect from an interface between a coating disposed on an interior portion of a probe and from an interface between a species immobilized on the probe and an environment external to the probe. The phase shift between these two sources of reflected light may depend on the amount of analyte immobilized on the probe and on the wavelength of the reflected light, which may affect the intensity of the reflected light measured. Analysis of the intensity of the reflected light as a function of wavelength may therefore be employed to determine an amount of analyte immobilized on the probe.

[0149] The value of an optical signal may be indicative of an amount and / or a type of species immobilized on a probe. At equilibrium, the amount of the species immobilized on a probe may be indicative of its affinity for the probe and / or another species immobilized on the probe. Additionally, the variation of an optical signal over time may be indicative of a rate at which a species becomes immobilized on a probe. The rate at which the species becomes immobilized on the probe may depend on the amount of analyte in the fluid to which the probe is exposed and / or the interaction between the species and the probe. As an example of the latter, the rate at which a species becomes immobilized on the probe may depend on the affinity of the species for the probe (and / or its surface chemistry and / or another species immobilized on the probe) and / or the rate at which the species binds to the probe (and / or its surface chemistry and / or another species immobilized on the probe). As another example of the latter, the rate at which a species is removed from the probe upon contact with a fluid other than that comprising the species (e.g., a different fluid, a refunctionalization fluid) may also be indicative of the affinity of the species for the probe (and / or its surface chemistry and / or another species immobilized on the probe) and / or the rate at which an analyte binds to the probe (and / or its surface chemistry and / or another species immobilized on the probe). Accordingly, the methods described herein may be suitable for determining the affinity of a species for a probe and / or another species immobilized on a probe. The affinity of a species for a probe may be parametrized by its association constant and / or its dissociation constant, as described in further detail below.

[0150] Without wishing to be bound by any particular theory, it is believed that any particular species may bind most rapidly to the probe upon initial contact between the fluid comprising the species (and / or a sample thereof) and the probe. Accordingly, it is also believed that measuring a variation in an optical signal may yield information that is more precise and / or may yield information more rapidly when the period of time over which the variation is measured comprises the initial contact between the fluid and the probe.

[0151] Variation in the optical signal may be indicative of changes in the amount of a species immobilized on a probe, which itself may be indicative of a measurement that is made before the amount of the species immobilized on the probe achieves a steady-state value. In this scenario, the rate at which the species immobilized on the probe approaches its steady-state value may vary with the concentration of the species in a fluid with which the probe is contacted, and so may be employed to assess the concentration of the species in that fluid. In some embodiments, the variation of the rate at which the species immobilized on the probe approaches its steady- state value varies more than the amount of the species immobilized on the probe at steady state. Accordingly, in some embodiments, measuring the rate at which a species becomes immobilized on a probe may provide a way to determine a concentration of the species that is more sensitive and / or more rapid than measuring an amount of the species immobilized on a probe at a final steady-state value.

[0152] A variety of suitable optical detector systems may be employed to detect the optical signals described herein. In some embodiments, an optical detector system may comprise an optical detector. Non-limiting examples of suitable types of optical detectors include photoncounting devices, spectrophotometers, spectrometers (e.g., Raman spectrometers, infrared spectrometers), polarization detectors, photodiodes, photodiode arrays, avalanche photodiodes, CMOS sensors, CCD sensors, CCD / CMOS sensors, imaging sensors, photomultiplier tubes, and microchannel plate detectors. In some embodiments, an optical detector is part of a plate reader.

[0153] In some embodiments, an optical detector system further comprises one or more additional components. For instance, an optical detector system may further comprise an optical cable. An optical cable may be capable of transmitting and / or configured to transmit light from a location at which it is generated and / or detectable to an optical detector. In some embodiments, the location from which an optical cable is capable of transmitting light is a probe. Light that is transmitted through the probe may be transmitted from the probe to the optical cable, through the optical cable, and to an optical detector.

[0154] In some embodiments, an optical detector system further comprises wavelength selector. Wavelength selectors may be capable of transmitting and / or configured to transmit some wavelengths of light at higher intensities than others. Some wavelength selectors may be capable of transmitting and / or configured to transmit negligible or no light at certain wavelengths. Without wishing to be bound by any particular theory, the presence of wavelength selectors in an optical detector system may advantageously enhance the detection of some wavelengths of light that are present at a relatively low intensity in comparison to other wavelengths of light also present. For instance, a wavelength selector may be present that is capable of transmitting and / or configured to transmit a relatively low amount of light supplied to stimulate fluorescent emission while being capable of transmitting and / or configured to transmit a relatively high amount of fluorescently emitted light.

[0155] Wavelength selectors may be provided at a variety of suitable locations in optical detector systems. Non-limiting examples of such locations include locations between a probe and an optical cable and between an optical cable and an optical detector.

[0156] Non-limiting examples of suitable wavelength selectors include filters, diffraction gratings, and prisms. In some embodiments, a wavelength selector is provided in conjunction with a bandwidth selector. The bandwidth selector may be capable of selecting and / or configured to select the size of the range of wavelengths to be transmitted through the wavelength selector. For wavelength selectors that have dispersion elements, the wavelength selector may take the form of an aperture or a slit that transmits light within a particular wavelength range. The width of the aperture or slit may be selected as desired considering the intensity of the light to be transmitted, sensitivity desired, and the closeness in wavelengths between the light desired to be transmitted and the light desired to not be transmitted.

[0157] The optical detector systems described herein may also be capable of detecting and / or configured to detect light at a single polarization and / or at a plurality of polarizations. When a light source is capable of detecting and / or configured to detect light at a plurality of polarizations, the optical detector system may further comprise one or more polarizing filters.

[0158] Such polarizing filter(s) may be positioned between a probe and an optical cable, between a fluid (e.g., a fluid with which a probe is in contact, was in contact, and / or will be in contact) and an optical cable, and between an optical cable and an optical detector. Polarizing filters may be beneficial if the optical signal comprises light polarized by a species immobilized on a probe and / or a species generated from a species immobilized on a probe.

[0159] Optical detector systems may be configured to receive light and / or capable of receiving light generated at a variety of locations. In some embodiments, an optical detector system is positioned proximal to a probe and / or a probe handling system. In such embodiments, the optical detector system may be capable of receiving and / or configured to receive light transmitted through the probe.

[0160] A variety of suitable light source systems may be employed to detect the optical signals described herein. In some embodiments, a light source system may comprise a light source. Non-limiting examples of suitable types of light sources include incandescent bulbs and / or lamps (e.g., xenon flash lamps, tungsten halogen lamps, mercury lamps, arc lamps), LEDs, and laser diodes.

[0161] In some embodiments, a method comprises employing a probe to detect an optical signal. Such probes may have a variety of suitable designs. Some probes suitable for such use are optical probes. Such probes may be part of one or more optical pathways present in an instrument employed in conjunction with the probe (e.g., between a light source system and a fluid with which the probe is in contact, between an optical detector system and a fluid with which the probe is in contact) and / or may be configured to transmit light. In some embodiments, a probe is transparent to and / or may transmit light at a plurality of wavelengths (e.g., visible wavelengths, infrared wavelengths, near infrared wavelengths, wavelengths of light emitted by a light source system, wavelengths of light that an optical detector system is capable of detecting and / or configured to detect). Some probes comprise one or more polished ends to facilitate transmission. Such polished ends may be perpendicular to the optical axis of the probe.

[0162] Probes may have a variety of suitable designs. In some embodiments, a probe is a fiber-optic probe and / or comprises an optical fiber. It is also possible for a probe to include two or more optical fibers. For instance, a probe may comprise a fiber-optic bundle. In some embodiments, a probe comprises one or more apertures through which light may be transmitted. For instance, a probe may comprise a plurality of optical fibers, and the terminus of each optical fiber may serve as an aperture through which light may be transmitted. When present, the apertures may be positioned on a side of the probe opposite a side on which any optical detector systems and / or light source systems are positioned. In such embodiments, the probe may serve to transmit light from a light source system to an aperture and / or to transmit light from an aperture to an optical detector system. It is also possible for a probe to comprise further optics (e.g., in addition to optical fibers) that assist with the transmission of light. As an example, a probe may comprise a lens and / or a pinhole. When present, these components may assist with near-field imaging. In some embodiments, a probe comprises a lens that is configured to collect and transmit light to the probe and / or a component thereof. As an example, the lens may be configured to collect and transmit light to an axis along the center and / or optical axis of the probe, along the center and / or optical axis of an optical fiber present in the probe, and / or along the center and / or optical axis of a fiberoptic bundle present in the probe.

[0163] In some embodiments, a probe comprises one or more components that allow it to be optically coupled to a light source system, an optical detector system, and / or a component thereof (e.g., an optical cable). As an example, in some embodiments, a probe comprises a component, such as a plastic hub, that is compatible with an SMA connector (e.g., an SMA905 connector), a BNC connector, a connector with push, lock, and / or twist functionality, and / or a compression spring. In some embodiments, a probe is coupled to an optical cable via a ferrule. The ferrule may comprise optical fibers comprising polished tips, which may facilitate optical communication with the probe. In some embodiments, a probe is capable of being and / or configured to be optically coupled to an optical cable that comprises one or more components to assist with strain relief at the location of the coupling.

[0164] In some embodiments, a probe comprises an interface internal thereto. As described above, such probes may be particularly suitable for generating optical signals comprising an amount of light that has been reflected from this interface and an amount of type of light that has been reflected from the end of the probe. In some embodiments, a probe lacks any interfaces internal thereto. In such embodiments, the probe may have a uniform composition throughout the probe and / or may lack composition and / or morphological variation that would cause appreciable reflection and / or scattering of light. Such probes may be particularly suitable for transmitting light that causes the generation of one or more of the following types of optical signals: light that has been emitted, transmitted, reflected, scattered, and / or polarized from a species immobilized on the probe; light that has been emitted, transmitted, reflected, scattered, and / or polarized from a species generated from a species immobilized on the probe; the absence of light that has been absorbed by a species immobilized on the probe; and the absence of light that has been absorbed by a species generated from a species immobilized on the probe. The presence of internal interfaces in probes employed to detect the above-described types of optical signals may undesirably reflect light back through the probe that has not impinged upon a species immobilized on the probe or generated from a species immobilized on a probe. Accordingly, probes lacking such internal interfaces (or including internal interfaces that reflect a relatively low amount of light) may be desirable for detecting such types of optical signals.

[0165] When present, interfaces internal to probes may have a variety of suitable designs. In some embodiments, a probe comprises an internal interface that takes the form of an interface between an interior portion of the probe and a coating disposed on the interior portion of the probe. FIG. 13 shows one non-limiting embodiment of a probe having such a design. The probe 1330 shown in FIG. 13 includes an internal interface 1332 between the interior portion of the probe 1334 and the coating 1336 disposed on the interior portion of the probe.

[0166] In some embodiments, a probe comprises a coating disposed on an interior portion of the probe and one or more further portions of the probe disposed on the coating. As one example, in some embodiments, a probe further comprises a second coating disposed on the coating disposed on the interior portion of the probe. The second coating may be formed from the same material as the interior portion of the probe. FIG. 14 shows one example of such a probe. In FIG. 14, the probe 1430 includes a second coating 1438 disposed on the coating 1436. The probe further includes an internal interface 1432 between the interior portion of the probe 1434 and the coating 1436 disposed on the interior portion of the probe. As another example, and as described in further detail below, in some embodiments, one or more species are immobilized on the probe (not shown), such as on the end of the probe. Such species may facilitate the performance of one or more assays and / or may be capable of immobilizing and / or configured to immobilize one or more species.

[0167] Probes, internal interfaces thereto, and coatings may have a variety of suitable shapes. For instance, a probe, an internal interface, and / or a coating may have a hexagonal and / or a round cross-section.

[0168] The various components of the probes described herein may have a variety of suitable compositions. In some embodiments, one or more portions of a probe (e.g., an interior portion, a coating, a second coating disposed on a coating disposed on an interior portion, the entirety of the probe) comprises a glass. Non-limiting examples of suitable glasses include SiO2 and Ta2Os.

[0169] In some embodiments, a probe comprises an interior portion and / or a second coating comprising SiO2 and a coating comprising Ta2Os. In some embodiments, one or more portions of a probe (e.g., an interior portion, a coating, a second coating disposed on a coating disposed on an interior portion, the entirety of the probe) comprises a polymer. Non-limiting examples of suitable polymers include polystyrene and polyethylene. The coatings described herein may have a variety of suitable thicknesses. In some embodiments, one or both of the coatings (and / or both coatings together) have a thickness of greater than or equal to 50 nm, greater than or equal to 100 nm, greater than or equal to 200 nm, greater than or equal to 500 nm, greater than or equal to 750 nm, greater than or equal to 1 micron, greater than or equal to 2 microns, greater than or equal to 3 microns, or greater than or equal to 4 microns. In some embodiments, one or both of the coatings (and / or both coatings together) have a thickness of less than or equal to 5 microns, less than or equal to 4 microns, less than or equal to 3 microns, less than or equal to 2 microns, less than or equal to 1 micron, less than or equal to 750 nm, less than or equal to 500 nm, less than or equal to 200 nm, or less than or equal to 100 nm. Combinations of the above-referenced ranges are also possible (e.g., greater than or equal to 50 nm and less than or equal to 5 microns, greater than or equal to 100 nm and less than or equal to 5 microns, or greater than or equal to 500 nm and less than or equal to 1 micron). Other ranges are also possible.

[0170] In some embodiments, a probe comprises a surface that is functionalized, that has a surface chemistry that assists with the performance of an assay, and / or has a surface chemistry that assists with the immobilization of a species thereon. The surface functionalization and / or chemistry may promote the immobilization thereon of reaction products that are typically generated during assays. For instance, the surface functionalization and / or chemistry may promote the immobilization of one or more species generated during the assay thereon. It is also possible for a surface functionalization and / or chemistry to promote the immobilization thereon of one or more species that may be present in a fluid with which the probe is in contact. In some embodiments, and as described above, a probe comprises a surface on which one or more species that are reagents are immobilized.

[0171] The reagent(s) may be immobilized on the probe in a variety of suitable manners. As an example, the reagent(s) may be bonded to the probe. The bonding may comprise covalent bonding, ionic bonding, polar bonding, van der Waals bonding, hydrophobic bonding, and / or hydrogen bonding.

[0172] In some embodiments, one or more reagents(s) may be immobilized on a probe in a manner such that they do not undergo significant (and / or any) detachment from the probe upon contact with one or more fluids (e.g., a fluid present during the performance of assay, a fluid possibly comprising a species to be immobilized on the probe, a refunctionalization fluid). For instance, the reagent(s) may be immobilized on the probe in a manner that is stable to water, aqueous solutions, buffers, acids, bases, and / or bodily fluids. However, it is also possible for one or more reagents to be initially immobilized on a surface of a probe that are then released from the surface of the probe during contact with one or more of fluids. As an example, a reagent that is initially immobilized on a surface of a probe may be configured to be released from the probe upon exposure to a particular stimulus. The stimulus may be present in a fluid.

[0173] Additionally or alternatively, it is possible for one or more reagent(s) to be immobilized on a probe in a manner such that the probe can be refunctionalized. It is also possible for a method to comprise refunctionalizing a probe. Refunctionalizing may comprise removing one or more reagent(s) from the probe. For instance, in some embodiments, refunctionalization comprises exposing a probe on which one or more reagent(s) are immobilized to a fluid (e.g., a buffer, such as an acidic buffer) that causes one or more of those reagent(s) to be detached from the probe. Afterwards, the probe may be exposed to a fluid comprising one or more new reagent(s) to be immobilized on the probe.

[0174] Refunctionalizing a probe may advantageously allow a probe to be employed during more than one method, during more than one assay, and / or to immobilize more than one type of analyte (e.g., as a non-consumable).

[0175] As an example, a first reagent and / or set of reagents may be immobilized on a probe prior to the performance of a first method, prior to the performance of a first assay. These reagents may be configured to undergo a chemical reaction with one or more species possibly present during the assay. If this chemical reaction does occur, the probe may be unsuitable for performing another assay unless it is refunctionalized because the chemical reaction may render the reagent(s) unsuitable for engaging in further chemical reactions. Accordingly, after performance of the assay, the probe may be refunctionalized to yield a probe onto which a new reagent and / or set of reagents can be immobilized, thus allowing for the probe to be employed during the performance of further assays. The reagent and / or set of reagents may be the same reagent and / or set of reagents initially immobilized on the probe, or may differ in one or more ways (e.g., if an operator desires to employ the probe to perform a different assay).

[0176] As another example, functionalizing a probe may advantageously allow a probe to be employed during more than one method and / or to immobilize more than one type of species. As an example, a first reagent and / or set of reagents may be immobilized on the probe prior to the determination of the concentration of a first species in a fluid. In some circumstances, it may be desirable to reuse the probe to determine the concentration of a second species in a fluid and / or a sample of the fluid (e.g., the same fluid as before, a different fluid). Accordingly, after detection of the concentration of the first species, the probe may be refunctionalized to yield a probe onto which a new reagent and / or set of reagents can be immobilized, thus allowing for the probe to be employed to detect the concentration of the second species.

[0177] It is also possible for some probes to not be regenerated and / or to be incapable of refunctionalization. Such probes may be employed as consumables.

[0178] A variety of suitable reagents may be immobilized on the surfaces of the probes described herein. Some reagents may be species that are capable of that engaging in one or more chemical reactions (e.g., one or more chemical reactions that may take place during an assay that the probe is employed to facilitate). For instance, a probe may comprise a reagent that is capable of bonding with another species (e.g., covalently, ionically, by polar interactions, by van der Waals interactions, hydrophobically, by hydrogen bonding, by complexing), absorbing another species, adsorbing another species, catalyzing a reaction of another species and / or between two or more species, decomposing (e.g., upon exposure to another species), undergoing a conformational shift, and / or catalyzing a reaction. In some embodiments, one or more of the previously described chemical reactions may cause the species with which the reagent reacts to become immobilized thereon. Selected non-limiting examples of suitable reagents include biomolecules (e.g., proteins, glycoproteins, peptides, nucleic acids (e.g., DNA, RNA, mRNA), antibodies (e.g., antibodies for exosomes, such as anti-CD63 and / or anti-CD9, antibodies for proteins, antibodies for viruses, antibodies for virus-like particles), antibody fragments, antigens, polysaccharides, carbohydrates, hormones, streptavidin, glutathione), ligands (e.g., ligands for proteins, such as protein A), small molecules, viruses, cells, inorganic compounds (e.g., aminopropylsilane), sequestration compounds, capsids, bacteria resins (e.g., Ni-NTA), plasmids, nutrient components, metabolics, metabolic byproducts, and combinations thereof. Non-limiting examples of proteins include protein A, protein G, protein L, and lectin. One non-limiting example of a combination of two or more of the previously described reagent types is a reagent that comprises protein A and an antibody to an exosome and / or a virus. The antibody may be immobilized on protein A immobilized on a probe surface and may be capable of immobilizing an exosome and / or a virus. In such embodiments, as well as others, two or more reagents are immobilized on a probe (and, in some embodiments, one or more such reagents may be a combination of two or more reagents).

[0179] In some embodiments, a species immobilized on a surface of a probe is suitable for engaging in a chemical and / or biological reaction that comprises binding. It is also possible for a probe to be suitable for engaging in a chemical and / or biological reaction that does not comprise binding. When present, binding may comprise a reaction between a target and a binding partner that specifically binds to the target (e.g., an agent or molecule that specifically binds to the target). Binding may also comprise immobilizing a target on the binding partner. In some embodiments, the binding partner may specifically bind to an epitope on the target molecule.

[0180] Non-limiting examples of specific pairs of binding partners and targets include an antibody and an antigen, an antibody fragment and an antigen, an antibody and a hapten, an antibody and a peptide, an antibody and a small molecule, an antigen and a fusion protein, an antibody fragment and a hapten, an enzyme and an enzymatic substrate, an enzyme and an inhibitor, an enzyme and a cofactor, a binding protein and a substrate, a carrier protein and a substrate, a protein and a small molecule, lecithin and a carbohydrate, a receptor and a hormone, a receptor and an effector, complementary strands of nucleic acid, a protein in combination with a nucleic acid repressor and an inducer, a ligand and a cell surface receptor, a virus and a ligand, and a receptor and a ligand.

[0181] Non-limiting examples of antibodies that may be binding partners or antibodies include intact (i.e., full-length) polyclonal and monoclonal antibodies, antigen-binding fragments of polyclonal and monoclonal antibodies (such as Fab, Fab', F(ab')2, or Fv), single chains (scFv) mutants of single chains, fusion proteins comprising an antibody portion, humanized antibodies, chimeric antibodies, diabodies, linear antibodies, single chain antibodies, multispecific antibodies (e.g., bispecific antibodies), and modified configurations of the immunoglobulin molecule that comprise an antigen recognition site of the required specificity. Non-limiting examples of antibodies falling into the last category include glycosylation variants of antibodies, amino acid sequence variants of antibodies, and covalently modified antibodies. Additionally, a binding partner may be an antibody of any class, such as IgD, IgE, IgG, IgA, or IgM (or subclass thereof, e.g., IgGl, IgG2, IgG3, IgG4, IgAl and / or IgA2).

[0182] An antigen may be a molecule or a portion of a molecule that can have antibodies generated against it. Antigens may be peptides, polysaccharides and / or lipids. Some antigens may originate from within the body (a “self-antigen”), and some antigens may originate from the external environment (a “non-self-antigen”).

[0183] In some embodiments, antibodies suitable for performing a chemical and / or biological reaction specifically bind to epitopes on their target molecules. An epitope (which may be referred to as an antigenic determinant) may be the part of the antigen recognized (or bound by) an antibody. For example, the epitope may be the specific piece of the antigen to which an antibody binds. The part of an antibody that binds to the epitope may be referred to as a paratope. An epitope may be a conformational epitope (composed of discontinuous amino acids or sections of the antigen) or a linear epitope (composed of continuous amino acids). Some proteins may share segments of high sequence homology and / or structural similarity.

[0184] These similar proteins may have common epitopes (in other words, the epitopes on different antibodies may be bound by the same antibody). Further, a protein that has been processed differentially (such as a protein that has gone a further enzymatic process) may share some, but not all epitopes with its pre-processing form. Non-limiting examples of different epitopes that may be added or removed during processing include N-terminal signal peptides (as seen, for example, on pre-pro-peptides) and changes seen when an inactive protein (e.g., a pro-peptide) is turned into an active form by post-translational modificatio

[0185] In some embodiments, a reagent may be immobilized on a surface of a probe via a covalent bond. Prior to such immobilization, the surface of the probe may be functionalized such that it comprises a plurality of functional groups suitable for forming such covalent bonds.

[0186] For instance, the surface of the probe may be functionalized by reaction with a bifunctional reagent comprising a siloxane group that facilitates attachment to the probe and a functional group that facilitates the formation of a covalent bond with the reagent to be immobilized on the probe. As another example, the surface of the probe may be exposed to a plasma or other treatment that generates functional groups in situ that facilitate the formation of a covalent bond with the reagent to be immobilized on the probe. Non-limiting examples of suitable types of functionals group that facilitate the formation of a covalent bond with the reagent to be immobilized on the probe include hydroxyls, amines, and carboxyls.

[0187] The probes described herein may comprise optical fibers having a variety of suitable diameters. In some embodiments, a probe comprises an optical fiber having a core with a diameter of greater than or equal to 400 microns, greater than or equal to 500 microns, greater than or equal to 600 microns, greater than or equal to 700 microns, greater than or equal to 800 microns, greater than or equal to 900 microns, greater than or equal to 1000 microns, greater than or equal to 1100 microns, greater than or equal to 1200 microns, greater than or equal to 1300 microns, greater than or equal to 1400 microns, greater than or equal to 1500 microns, greater than or equal to 1600 microns, greater than or equal to 1700 microns, greater than or equal to 1800 microns, or greater than or equal to 1900 microns. In some embodiments, a probe comprises an optical fiber having a core with a diameter of less than or equal to 2000 microns, less than or equal to 1900 microns, less than or equal to 1800 microns, less than or equal to 1700 microns, less than or equal to 1600 microns, less than or equal to 1500 microns, less than or equal to 1400 microns, less than or equal to 1300 microns, less than or equal to 1200 microns, less than or equal to 1100 microns, less than or equal to 1000 microns, less than or equal to 900 microns, less than or equal to 800 microns, less than or equal to 700 microns, less than or equal to 600 microns, or less than or equal to 500 microns. Combinations of the above-referenced ranges are also possible (e.g., greater than or equal to 400 microns and less than or equal to 2000 microns). Other ranges are also possible.

[0188] As described elsewhere herein, some methods may comprise performing assays (e.g., that involve a step of detecting an optical signal).

[0189] In some embodiments, the performance of an assay comprises contacting a probe with one or more fluids (and, in some embodiments, subsequently removing the probe from contact with such fluid(s)) and detecting one or more optical signals.

[0190] During assay performance, an optical signal may be associated with a species immobilized on a probe and / or a species present in a fluid with which the probe is in contact.

[0191] In some embodiments, an optical signal is detected while a probe is in contact with a fluid. It is also possible for an optical signal to be generated upon initial contact between a probe and a fluid. In some embodiments, detection of an optical signal comprises detecting the location at which the optical signal was generated. This may be accomplished by detecting a position of a probe transmitting the optical signal to a detector.

[0192] When a probe is contacted with two or more fluids, it may be removed from contact with each fluid with which it they in contact with before contacting the next fluid. In some embodiments, removing a probe from contact with a fluid stops a reaction from occurring (e.g., a reaction between a species immobilized on a probe and a species present in the fluid from which the probe is removed). Stopping a reaction by removing a probe from contact with a fluid may be performed in response to an optical signal (e.g., an optical signal indicative of the fluid and / or a sample with which the probe was in contact prior to contacting the fluid). It is also possible for a reaction to be stopped by removing a probe from contact with a fluid after a preset interval has elapsed and / or by manual action of an operator.

[0193] The sequential contacting of a probe with two or more fluids may be effectuated by translating the probe(s), a probe handling system, and / or a support structure. The translating may be performed according to a pre-set program in which the probe is positioned at a plurality of locations for a plurality of times. It is also possible for an instrument to be configured such that an operator can translate the probe at will (e.g., an operator may be able to input a desired location to which the probe is translated location and / or to move the probe in real time by use of a controller). Additionally, some instruments may be configured such that they are not configured to translate a probe. In such embodiments, the probe may be stationary or immovable absent manual movement by an operator.

[0194] Pre-set programs may comprise some or all of the following sequential steps: translating the probe horizontally (e.g., in a first horizontal direction, in a second horizontal direction perpendicular to the first horizontal direction, in a combination of the two directions) until it is positioned above a container and / or a portion thereof (e.g., a well in a multi-well plate), either pausing for a defined amount of time (during which the container may be raised such that any fluid in the portion of the container, such as a well therein, contacts the probe) or lowering the probe until it contacts any fluid in the portion of the container (e.g., well), maintaining the probe in a position such that it contacts any fluid in the portion of the container (e.g., well) for a defined amount of time, and either pausing for a defined amount of time (during which the container may be lowered such that any fluid in the portion of the container, such as a well, no longer contacts the probe) or raising the probe until it no longer contacts any fluid in the portion of the container (e.g., well). Pre-set programs may repeat the above some or all of these sequential steps such that the probe sequentially contacts a plurality of fluids contained in a plurality of containers and / or portions thereof (e.g., a plurality of wells in a multi-well plate). Further examples of steps that pre-set programs may comprise include pre-wet (e.g., coating dissolution), initiation, calibration, reference, and / or shut-down steps.

[0195] Some assays comprise detecting one or more qualitative features of a sample (e.g., the presence absence of a species of interest, such as a protein). Some assays comprise detecting one or more quantitative features of a sample (e.g., the amount of a species of interest present in the sample, such as the amount of a protein present in the sample). In some embodiments, an assay comprises performing a kinetic measurement (e.g., the rate of binding of a species in a fluid, such as a sample, to a species immobilized on a probe) and / or a pulse measurement.

[0196] In some embodiments, an assay comprises performing a pulse measurement, such as a measurement performed during a flash luminescence reaction and / or a flash reaction. Some suitable flash luminescence reactions and flash reactions comprise contacting a probe with a species immobilized thereon that is a catalyst for a reaction and then measuring an optical signal associated with a species generated by that reaction.

[0197] A variety of suitable assays may be performed, non-limiting examples of which include ELISA assays (e.g., direct ELISA assays, indirect ELISA assays, sandwich ELISA assays), whole cell assays, and biomolecular interaction assays. Some assays may comprise detecting cell surface proteins, empty capsids, and / or capsids containing nucleic acids.

[0198] In some embodiments, an assay is performed on a sample. In such embodiments, at least one fluid with which a probe is contacted during the assay may comprise a fluid that is a sample. It is also possible for a fluid to which light is transmitted for optical signal detection to be a sample. The sample may be a fluid with which a probe is contacted and / or may be present in (e.g., suspended in, dissolved in) one fluid with which a probe is contacted. It is also possible for two or more (or each) pluralities of fluids employed in an assay to comprise a fluid that is a sample. In some embodiments, performing an assay comprises contacting at least one probe with at least one plurality of fluids that lack any fluids that are samples.

[0199] In some embodiments, a sample comprises a component that becomes immobilized on a probe during performance of the assay and / or is configured to become immobilized on a probe during performance of the assay. For instance, in some embodiments, a sample comprises a component that binds to a probe and / or is configured to bind to a probe. It is also possible for the performance of an assay to determine whether or not a sample comprises such components. For instance, in some embodiments, a sample may comprise an antigen for an antibody immobilized on a probe. Performing the assay may identify whether the sample in fact comprises an antigen and / or the concentration of such an antigen in the sample. As further examples, as described above, a reagent may be immobilized on a surface of a probe that is suitable for engaging in a chemical and / or biological reaction that comprises binding, and the sample may comprise a binding partner and / or target for that reagent. For instance, an antigen may be immobilized on the surface of a probe and the sample may comprise an antibody for that antigen (e.g., an enzyme-linked antibody for that antigen).

[0200] Some samples may comprise bodily fluids and / or biological materials. As an example, in some embodiments, a sample comprises cells (e.g., live cells) and / or reagents (e.g., biomolecules). Samples may comprise some or all of the reagents described elsewhere herein with respect to the reagents that may be immobilized on the surface of a probe and / or may comprise reagents other than those so described. Non-limiting examples of some reagents that may be included in samples suitable for being analyzed by an assay include proteins (e.g., protein A, protein G, protein L, host cell proteins, Fc receptors, streptavidin), glycoproteins, peptides, ligands, antibodies (e.g., IgG), antigens, small molecules, viruses, capsids, cells, (e.g., Chinese hamster ovary cells), differentiated cell types, polysaccharides, bacteria, hormones, nucleic acids (e.g., DNA, RNA, mRNA), carbohydrates, small molecules, inorganic compounds, ions (e.g., nickel ions) , sequestration compounds, and bacteria. In some embodiments, a fluid comprises a reagent that is a protein tagged by a recombinant modification. Non-limiting examples of tagged proteins include His-tagged proteins and biotin-tagged proteins.

[0201] Non-limiting examples of reagents that may be present in fluids described herein and / or configured to be immobilized on a species immobilized on a probe include ligands (e.g., ligands for analytes present in the sample), binding partners and / or targets for analytes present in samples, antibodies (e.g., antibodies for antigens present in the sample, enzyme- linked antibodies, primary enzyme-linked antibodies, secondary enzyme-linked antibodies, enzyme-linked antibodies for antigens present in samples, antibodies comprising fluorophores), proteins, glycoproteins, peptides, nucleic acids, antigens, polysaccharides, carbohydrates, hormones, small molecules, viruses, cells, inorganic compounds, sequestration compounds, capsids, and bacteria. In some embodiments, a reagent comprises an enzyme and / or is bonded to an enzyme. Non-limiting examples of suitable enzymes include horseradish peroxidase and alkaline phosphatase.

[0202] In some embodiments, a fluid that comprises one or more reagents configured to generate an optical signal is present during the performance of an assay. Such fluids may be provided separately from any samples, standards, and / or fluids comprising species that assist with the performance of the assay (e.g., in a separate well in a multi-well plate), one or more reagents, and / or fluids comprising species that assist with the performance of the assay. One example of such a fluid is a fluid that comprises a reagent that is configured to react with a species immobilized on a probe (e.g., a reagent initially present in a sample, a species immobilized on a reagent initially present in the sample). Reagents configured to react with reagents immobilized on a probe may generate an optical signal upon undergoing such a reaction. For instance, a fluid may comprise a reagent configured to undergo a reaction with a species immobilized on a probe that generates a species that absorbs light, transmits light, reflects light, fluoresces light, undergoes scattering (e.g., Raman scattering), is polarized, and / or undergoes luminescence (e.g., chemiluminescence). In some embodiments, an optical signal is detected while a probe is in contact with a fluid that comprises one or more reagents configured to generate an optical signal and / or upon initial contact with such a fluid.

[0203] Non-limiting examples of reagents that may be configured to generate an optical signal include enzyme substrates (e.g., for enzyme-linked antibodies). Some methods comprise reacting an enzyme substrate with an enzyme (e.g., an enzyme-linked antibody). Such a reaction may result in the generation of products of an enzymatic reaction, one or more of which may be capable of and / or configured to generate an optical signal. In some embodiments, one or more wash fluids is present during the performance of an assay. Wash fluids may be provided separately from any samples, standards, fluids comprising species that assist with the performance of the assay, and / or fluids comprising reagents configured to generate an optical signal (e.g., in a separate well in a multi-well plate), one or more standards, one or more reagents, fluids comprising species that assist with the performance of the assay, and / or fluids comprising reagents configured to generate an optical signal. A wash fluid may be a fluid that is configured to remove species that are weakly adhered to a probe. Removing such species from a probe may enhance the reproducibility of the assay by eliminating signal from a species that is not immobilized on thereon. Additionally, removing such species from a probe may reduce cross -contamination between different fluids present during the assay. One example of a suitable wash fluid is a wash buffer (e.g., a glycin buffer, a phosphoric acid buffer).

[0204] In some embodiments, an assay is conducted by sequentially contacting a probe on which a reagent is immobilized with the following fluids: a sample comprising a first reagent configured to be immobilized on the probe, a fluid comprising a second reagent configured to become immobilized on the first reagent, and a fluid comprising a third reagent configured to react with the second reagent to generate a species that generates an optical signal. As another example, an assay may comprise sequentially contacting a probe on which a reagent is immobilized with the following fluids: a sample comprising a first reagent configured to be immobilized on the probe, a fluid comprising a second reagent configured to become immobilized on the first reagent, a fluid comprising a third reagent configured to become immobilized on the second reagent, and a fluid comprising a fourth reagent configured to react with the third reagent to generate a species that generates an optical signal. It is also possible for a process to be performed in which a standard is the first fluid contacted by the probe but for which the other steps are the same as those in one of the preceding two sentences. Additionally, some methods may comprise contacting a probe with a wash fluid (e.g., a wash buffer) in between two or more of pairs of the steps described above.

[0205] The fluids employed during the assays described herein may be contained in containers having one or more features described elsewhere herein. In some embodiments, some or all of such fluids are contained containers positioned in one or more multi-well plates. In such embodiments, the fluids may be contained in separate containers, which may take the form of separate wells. The wells may be in a single common row, a common set of rows, a single common column, or a common set of columns. It is also possible for a method to comprise contacting a probe with a plurality of fluids that are positioned in two or more columns or two or more rows. During performance of the assay, a probe may be translated across one or more containers containing a plurality of fluids and / or a support structure on which one or more such container(s) are supported may be translated with respect to the probe. For instance, in the case of a multi-well plate, a probe may be translated across a plurality of wells in the multi-well plate. Some or all of those wells may contain the fluids employed to perform the assay. As another example, a support structure on which a multiwell plate is supported may be translated so that a plurality of wells (some or all of which contain fluids suitable for performing the assay) are sequentially positioned proximal to a probe.

[0206] Performance of an assay may also comprise one or more steps and / or periods of time in which both a support structure and a probe are stationary, in which all parts of the instrument employed to perform the assay are stationary, in which two or more parts of the instrument are stationary with respect to each other, and / or in which two or more parts of the instrument (despite being non-stationary with respect to each other) do not experience appreciable net displacement from each other. As an example, in some embodiments, a method comprises one or more periods of time during which a probe is incubated with a fluid. The incubation may occur while both the probe and the fluid (and, possibly, a container containing the fluid and / or a support structure supporting such a container) are stationary. It is also possible for the incubation to occur while either the fluid (and, possibly, a container containing the fluid and / or a support structure supporting such a container) and / or a probe are shaking. In some embodiments, both the fluid (and, possibly, a container containing the fluid and / or a support structure supporting such a container) and the probe shake together. In some embodiments, incubation comprises agitating the fluid (e.g., a sample) and / or mixing the fluid. The agitation and / or mixing may be accomplished by stirring the fluid (e.g., with the probe).

[0207] It is also possible for incubation to comprise adjusting and / or maintaining the temperature of the fluid. For instance, incubation may comprise heating the fluid and / or cooling the fluid.

[0208] In some embodiments, an optical signal may be generated and / or detected during one or more steps and / or periods of time in which both a support structure and a probe are stationary, in which all parts of the instrument are stationary, in which two or more parts of the instrument are stationary with respect to each other, and / or in which two or more parts of the instrument (despite being non-stationary with respect to each other) do not experience appreciable net displacement from each other. The detection may occur during incubation and / or in the absence of incubation.

[0209] EXAMPLE 1

[0210] This Example describes an exemplary article comprising a plurality of containers for fluids.

[0211] FIG. 15 shows one non-limiting example of an article comprising a plurality of containers for fluids. These containers for fluids have bottoms comprising measurement portions suitable for reflecting light impinging vertically thereon from a probe away from the probe.

[0212] EXAMPLE 2

[0213] This Example describes the reflection of light from exemplary measurement portions.

[0214] FIGs. 16-18 and 19-22 show the reflection of light from measurement portions comprising a cone (FIGs. 16, 14, 19, 20, and 22) and a plurality of sawteeth (FIGs. 17 and 21). As can be seen from these FIGs., light transmitted through an end of a probe onto these measurement portions is reflected by these measurement portions such that it is not incident on the bottom of the probe. In FIGs. 16-17, “Fiber / Sensor Tip” refers to the probe and “well” refers to the container for the fluid.

[0215] EXAMPLE 3

[0216] This Example describes an exemplary article comprising a plurality of containers for fluids.

[0217] FIGs. 23-26 show various mechanical drawings of one non-limiting example of an article comprising a plurality of containers for fluids. These containers for fluids have bottoms comprising measurement portions suitable for reflecting light impinging vertically thereon from a probe away from the probe.

[0218] EXAMPLE 4

[0219] This Example describes exemplary containers for fluids comprising coatings.

[0220] FIGs. 27 and 28 show two examples of containers for fluids comprising a single lightabsorbing coating disposed on a substrate. As can be seen from these Figures, these coatings comprise a polymer having a refractive index that is the same as the refractive index of the fluid intended to be contained by the containers. FIGs. 29 and 30 show two examples of containers for fluids comprising a first lightabsorbing coating disposed on a substrate and a second coating that is not light-absorbing disposed on the first coating. As can be seen from these Figures, the second coatings comprise a polymer having a refractive index that is the same as the refractive index of the fluid intended to be contained by the containers.

[0221] FIG. 31 shows a further example of a container for a fluid comprising a lightabsorbing coating. This light- absorbing coating also reduces the amount of light reflected via specular reflection by scattering light at its surface. As can be seen in FIG. 31, the lightabsorbing coating depicted therein comprises microparticles.

[0222] EXAMPLE 5

[0223] This Example compares the performance of scratched containers having flat measurement portions to scratched containers having a measurement portion comprising a cone projecting vertically upwards.

[0224] Light was transmitted through an end of a probe to a fluid positioned in each container. During such light transmission, the containers were shaken at 300 rpm. The wavelength shift of the measured interference pattern as a function of time is shown in FIGs. 32 and 33, with each trace depicting data from a different channel. FIG. 32 shows the wavelength shift for the containers having flat measurement portions and FIG. 33 shows the wavelength shift for containers having a measurement portion comprising a cone projecting vertically upwards. As can be seen from these Figures, there is less variation in the wavelength shift for the latter. This indicates that such designs are able to provide better, lower-noise performance even when containing surface imperfections than containers having flat measurement portions.

[0225] While several embodiments of the present invention have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and / or structures for performing the functions and / or obtaining the results and / or one or more of the advantages described herein, and each of such variations and / or modifications is deemed to be within the scope of the present invention. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and / or configurations will depend upon the specific application or applications for which the teachings of the present invention is / are used. Those skilled in the art will recognize or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, the invention may be practiced otherwise than as specifically described and claimed. The present invention is directed to each individual feature, system, article, material, kit, and / or method described herein. In addition, any combination of two or more such features, systems, articles, materials, kits, and / or methods, if such features, systems, articles, materials, kits, and / or methods are not mutually inconsistent, is included within the scope of the present invention.

[0226] All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and / or ordinary meanings of the defined terms.

[0227] The indefinite articles “a” and “an,” as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean “at least one.”

[0228] The phrase “and / or,” as used herein in the specification and in the claims, should be understood to mean “either or both” of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Multiple elements listed with “and / or” should be construed in the same fashion, i.e., “one or more” of the elements so conjoined. Other elements may optionally be present other than the elements specifically identified by the “and / or” clause, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, a reference to “A and / or B”, when used in conjunction with open-ended language such as “comprising” can refer, in one embodiment, to A only (optionally including elements other than B); in another embodiment, to B only (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc.

[0229] As used herein in the specification and in the claims, “or” should be understood to have the same meaning as “and / or” as defined above. For example, when separating items in a list, “or” or “and / or” shall be interpreted as being inclusive, i.e., the inclusion of at least one, but also including more than one, of a number or list of elements, and, optionally, additional unlisted items. Only terms clearly indicated to the contrary, such as “only one of’ or “exactly one of,” or, when used in the claims, “consisting of,” will refer to the inclusion of exactly one element of a number or list of elements. In general, the term “or” as used herein shall only be interpreted as indicating exclusive alternatives (i.e. “one or the other but not both”) when preceded by terms of exclusivity, such as “either,” “one of,” “only one of,” or “exactly one of.” “Consisting essentially of,” when used in the claims, shall have its ordinary meaning as used in the field of patent law.

[0230] As used herein in the specification and in the claims, the phrase “at least one,” in reference to a list of one or more elements, should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed within the list of elements and not excluding any combinations of elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified within the list of elements to which the phrase “at least one” refers, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, “at least one of A and B” (or, equivalently, “at least one of A or B,” or, equivalently “at least one of A and / or B”) can refer, in one embodiment, to at least one, optionally including more than one, A, with no B present (and optionally including elements other than B); in another embodiment, to at least one, optionally including more than one, B, with no A present (and optionally including elements other than A); in yet another embodiment, to at least one, optionally including more than one, A, and at least one, optionally including more than one, B (and optionally including other elements); etc.

[0231] It should also be understood that, unless clearly indicated to the contrary, in any methods claimed herein that include more than one step or act, the order of the steps or acts of the method is not necessarily limited to the order in which the steps or acts of the method are recited.

[0232] In the claims, as well as in the specification above, all transitional phrases such as “comprising,” “including,” “carrying,” “having,” “containing,” “involving,” “holding,” “composed of,” and the like are to be understood to be open-ended, i.e., to mean including but not limited to. Only the transitional phrases “consisting of’ and “consisting essentially of’ shall be closed or semi-closed transitional phrases, respectively, as set forth in the United States Patent Office Manual of Patent Examining Procedures, Section 2111.03.

Claims

CLAIMS1. An article, comprising: a container for a fluid, wherein: the container comprises a measurement portion; the measurement portion has a geometry such that less than or equal to 50% of light impinging vertically thereon reflects at an angle of less than or equal to 35° with respect to a vertical axis; and a variation in a height of the measurement portion is less than or equal to 1.6 mm.

2. A method, comprising: transmitting light through an end of a probe to a fluid positioned in a container; and detecting an optical signal based on the interaction of the light with one or more species present in the fluid and / or immobilized on the probe, wherein: the container comprises a measurement portion; the measurement portion is positioned beneath the probe; the measurement portion has a geometry such that less than or equal to 50% of light impinging vertically thereon reflects at an angle of less than or equal to 35° with respect to a vertical axis; a variation in a height of the measurement portion is less than or equal to 1.6 mm.

3. An article, comprising: a container for a fluid, wherein: the container comprises a measurement portion; the measurement portion has a geometry such that less than or equal to 50% of light impinging vertically thereon reflects at an angle to the vertical of less than or equal to 18° when the article is untilted; and a variation in a height of the measurement portion is less than or equal to 1.75 mm.

4. A method, comprising: transmitting light through an end of a probe to a fluid positioned in a container; and detecting an optical signal based on the interaction of the light with one or more species present in the fluid and / or immobilized on the probe, wherein: the container comprises a measurement portion; the measurement portion is positioned beneath the probe; the measurement portion has a geometry such that less than or equal to 50% of light impinging vertically thereon reflects at an angle to the vertical of less than or equal to 18° when the article is untilted; a variation in a height of the measurement portion is less than or equal to 1.75 mm; and the optical signal is detected while an article in which the container is positioned is tilted at an angle of less than or equal to 45°.

5. An article, comprising: a container for a fluid, wherein: the container comprises a measurement portion; the measurement portion comprises a substrate and a coating disposed on the substrate; the coating comprises a plurality of light-absorbing particles and a polymer; and the measurement portion has a geometry such that less than or equal to 50% of light impinging vertically thereon reflects at an angle of less than or equal to 35° with respect to a vertical axis.

6. A method, comprising: transmitting light through an end of a probe to a fluid positioned in a container; and detecting an optical signal based on the interaction of the light with one or more species present in the fluid and / or immobilized on the probe, wherein: the container comprises a measurement portion; the measurement portion is positioned beneath the probe;the measurement portion comprises a substrate and a coating disposed on the substrate; the coating comprises a plurality of light-absorbing particles and a polymer; and the measurement portion has a geometry such that less than or equal to 50% of light impinging vertically thereon reflects at an angle of less than or equal to 35° with respect to a vertical axis.

7. An article, comprising: a container for a fluid, wherein: the container comprises a measurement portion; the measurement portion comprises a substrate, a light-absorbing coating disposed on the substrate, and a compatibilizing coating disposed on the light- absorbing coating; and the measurement portion has a geometry such that less than or equal to 50% of light impinging vertically thereon reflects at an angle of less than or equal to 35° with respect to a vertical axis.

8. A method, comprising: transmitting light through an end of a probe to a fluid positioned in a container; and detecting an optical signal based on the interaction of the light with one or more species present in the fluid and / or immobilized on the probe, wherein: the container comprises a measurement portion; the measurement portion is positioned beneath the probe; the measurement portion comprises a substrate, a light-absorbing coating disposed on the substrate, and a compatibilizing coating disposed on the light- absorbing coating; and the measurement portion has a geometry such that less than or equal to 50% of light impinging vertically thereon reflects at an angle of less than or equal to 35° with respect to a vertical axis.

9. An article, comprising: a container for a fluid, wherein:the container comprises a measurement portion; the measurement portion has a surface roughness of greater than or equal to0.2 Ra and less than or equal to 1 Ra; and the measurement portion has a geometry such that less than or equal to 50% of light impinging vertically thereon reflects at an angle of less than or equal to 35° with respect to a vertical axis.

10. A method, comprising: transmitting light through an end of a probe to a fluid positioned in a container; and detecting an optical signal based on the interaction of the light with one or more species present in the fluid and / or immobilized on the probe, wherein: the container comprises a measurement portion; the measurement portion is positioned beneath the probe; the measurement portion has a surface roughness of greater than or equal to0.2 Ra and less than or equal to 1 Ra; and the measurement portion has a geometry such that less than or equal to 50% of light impinging vertically thereon reflects at an angle of less than or equal to 35° with respect to a vertical axis.

11. An article as in any one of claims 1, 3, 5, 7, and 9, wherein the container is positioned in an article comprising a plurality of containers.

12. An article as in any one of claims 1, 3, 5, 7, and 9, wherein the article is a multi- well plate.

13. An article as in any one of claims 1, 3, 5, 7, and 9, wherein the container is a well.

14. A method as in any one of claims 2, 4, 6, 8, and 10, wherein the optical signal is detected while the article is shaking.

15. A method as in claim 14, wherein the shaking comprises translating the container along an orbital pathway.

16. A method as in any one of claims 2, 4, 6, 8, and 10, wherein the container has a geometry such that less than or equal to 50% of the light is reflected from the container into the end of the probe during detection of the optical signal.

17. An article as in any one of claims 1, 3, 5, 7, and 9, wherein a center of the measurement portion is positioned less than or equal to 1 mm from a center of a portion of the container positioned vertically beneath the probe.

18. An article as in any one of claims 1, 3, 5, 7, and 9, wherein a center of the measurement portion is positioned less than or equal to 2 mm from a center of a portion of the container positioned vertically beneath the probe.

19. An article as in any one of claims 1, 3, 5, 7, and 9, wherein the measurement portion comprises a cone projecting vertically upwards.

20. An article as in any one of claims 1, 3, 5, 7, and 9, wherein the measurement portion comprises a cone projecting vertically downwards.

21. An article as in claim 19, wherein the cone has an angle to the vertical of greater than or equal to 5°.

22. An article as in any one of claims 1, 3, 5, 7, and 9, wherein the measurement portion comprises a plurality of sawteeth.

23. An article as in claim 22, wherein an angle between the hypotenuse of the sawteeth and the horizontal direction is greater than or equal to 5° and less than or equal to 45°.

24. An article as in any one of claims 1, 3, 5, 7, and 9, wherein an external surface of a bottom of the container is flat.

25. An article as in any one of claims 1, 3, 5, 7, and 9, wherein an internal surface of a bottom of the container has a surface roughness of less than or equal to 0.7 Ra.

26. An article as in any one of claims 1, 3, 5, 7, and 9, wherein an internal surface of a bottom of the container has a surface roughness of less than or equal to 1 Ra.

27. An article as in any one of claims 1, 3, 5, 7, and 9, wherein the bottom of the container is opaque.

28. An article as in any one of claims 1, 3, 5, 7, and 9, wherein the container comprises a plastic.

29. A method as in any one of claims 2, 4, 6, 8, and 10, wherein the optical signal is detected while an article in which the container is positioned is tilted at an angle of less than or equal to 45°.

30. An article as in any one of claims 1, 3, 5, 7, and 9, wherein the measurement portion is flat.

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