Methods for detecting contact between sensors and liquids

Abstract

Techniques for detecting contact between sensors and liquids, associated instruments, associated methods, and associated non-transitory computer-readable media are generally provided. Some techniques described herein are particularly suitable for use in detecting when a probe, inserted into a container holding liquid, initially contacts a surface of the liquid. Some instruments described herein are configured to detect contact between a sensor and a liquid as described herein. Some methods described herein perform detection of contact between a sensor and a liquid as described herein. Some non-transitory computer-readable- media described herein include processor-executable instructions for detecting contact between a sensor and a liquid as described herein.

Description

[0001] METHODS FOR DETECTING CONTACT BETWEEN SENSORS AND LIQUIDS

[0002] RELATED APPLICATIONS

[0003] This application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Application No.: 63 / 729,214, filed December 6, 2024, under Attorney Docket No.: S2164.70012US00, and entitled “METHODS FOR DETECTING CONTACT BETWEEN SENSORS AND LIQUIDS,” which is incorporated herein by reference in its entirety.

[0004] FIELD

[0005] Techniques for detecting contact between sensors and liquids, associated instruments, associated methods, and associated non-transitory computer-readable media are generally described.

[0006] BACKGROUND

[0007] Sensors may be employed to detect characteristics of a liquid. For example, a probe may be inserted into a container to obtain an optical signal indicating characteristics of a liquid held by the container.

[0008] Accordingly, new techniques for detecting contact between sensors and liquids, associated instruments, and methods of use thereof would be beneficial.

[0009] SUMMARY

[0010] The present disclosure generally describes techniques for detecting contact between sensors and liquids, associated instruments, associated methods, and associated non-transitory computer-readable media. 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 instrument is provided. The instrument comprises a probe configured to transmit light, an optical detector configured to receive an optical signal from the probe, and a processor operatively coupled to memory. The instrument is configured to insert the probe into a container holding liquid at least until an end of the probe initially contacts a surface of the liquid. The optical signal comprises a first portion of the light reflected by an interface internal to the probe and a second portion of the light reflected by the end of the probe. The processor is configured to, based on electrical signals produced by the optical detector over time indicating content of the optical signal, identify a time at which the probe initially contacts the surface of the liquid during insertion of the probe into the container.

[0012] In some embodiments, a method is provided. The method comprises transmitting, by a probe of an instrument, light, and receiving, by an optical detector of the instrument, an optical signal from the probe. The probe is inserted into a container holding a liquid at least until an end of the probe initially contacts a surface of the liquid. The method further comprises identifying, by a processor of the instrument that is operatively coupled to memory of the instrument, based on electrical signals produced by the optical detector over time indicating content of the optical signal, a time at which the probe initially the contacts the surface of the liquid during insertion of the probe into the container. The optical signal comprises a first portion of the light reflected by an interface internal to the probe and a second portion of the light reflected by the end of the probe.

[0013] In some embodiments, a non-transitory computer-readable medium is provided. The non-transitory computer-readable medium has instructions stored thereon that, when executed by a processor, cause the processor to perform a method. The method comprises identifying, based on electrical signals produced by an optical detector of an instrument over time indicating content of an optical signal, a time at which a probe of the instrument initially contacts a surface of a liquid during insertion of the probe into a container holding the liquid. The probe transmits light, the optical detector receives the optical signal from the probe as the probe is inserted into the container at least until an end of the probe initially contacts the surface of the liquid, and the optical signal comprises a first portion of the light reflected by an interface internal to the probe; and a second portion of the light reflected by the end of the probe.

[0014] Other advantages and novel features of the present disclosure will become apparent from the following detailed description of various non-limiting embodiments of the disclosure 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.

[0015] BRIEF DESCRIPTION OF THE DRAWINGS Non-limiting embodiments of the present disclosure 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 disclosure shown where illustration is not necessary to allow those of ordinary skill in the art to understand the disclosure. In the figures:

[0016] FIG. 1 shows one non-limiting example of an instrument including processing circuitry configured to detect contact between a sensor and a liquid, in accordance with some embodiments;

[0017] FIG. 2 shows one non-limiting example of a system including an instrument including processing circuitry configured to detect contact between a sensor and a liquid, in accordance with some embodiments;

[0018] FIGs. 3A-3D show one non-limiting example sequence of inserting probes of an instrument into respective containers holding liquid, in accordance with some embodiments;

[0019] FIG. 4A shows a non-limiting example of an optical signal including a first portion of transmitted light reflected from an interface internal to a probe and a second portion of transmitted light reflected from an end of the probe, in accordance with some embodiments;

[0020] FIG. 4B shows a non-limiting example of relative light intensity vs. wavelength for the optical signal of FIG. 4 A, in accordance with some embodiments;

[0021] FIG. 5A shows a non-limiting example of an optical signal including a first portion of transmitted light reflected from the interface internal to the probe of FIG. 4A and a second portion of transmitted light reflected from the end of the probe having a species immobilized thereon, in accordance with some embodiments;

[0022] FIG. 5B shows a non-limiting example of relative light intensity vs. wavelength for the optical signal of FIG. 5 A, in accordance with some embodiments;

[0023] FIGs. 6A and 6B show a non-limiting example of a fiber bundle coupled to a probe that may be included in an instrument described or system herein, in accordance with some embodiments;

[0024] FIGs. 7A and 7B show a non-limiting example of a fiber bundle that may be included in an instrument or system described herein, in accordance with some embodiments;

[0025] FIG. 8 shows a non-limiting example of a fiber bundle with coupling end removed, in accordance with some embodiments; FIG. 9 shows a non-limiting example of a cable configuration for transmitting light to and receiving optical signals from a plurality of probes, in accordance with some embodiments;

[0026] FIG. 10 shows an alternative non-limiting example of a cable configuration for transmitting light to and receiving optical signals from a plurality of probes, in accordance with some embodiments;

[0027] FIG. 11 shows a first non-limiting example of measurement data initialized at a time at which a probe initially contacts a surface of a liquid, in accordance with some embodiments;

[0028] FIG. 12 shows a second non-limiting example of measurement data initialized at a time at which a probe initially contacts a surface of a liquid, in accordance with some embodiments;

[0029] FIG. 13 shows a third non-limiting example of measurement data initialized at a time at which a probe initially contacts a surface of a liquid, in accordance with some embodiments;

[0030] FIG. 14 shows an example of measurement data initialized at a predetermined time, in accordance with some embodiments;

[0031] FIG. 15 shows a non-limiting example of measurement data including a first portion initialized at a first time at which a probe initially contacts a surface of a first liquid and a second portion initialized at a second time at which the probe initially contacts a surface of a second liquid, in accordance with some embodiments;

[0032] FIG. 16 shows non-limiting example averages of the measurement data shown in FIG. 15, in accordance with some embodiments;

[0033] FIGs. 17A-17C show non- limiting example fits of the measurement data shown in FIG. 15, in accordance with some embodiments;

[0034] FIG. 18 shows an example of measurement data including a first portion initialized at a first predetermined time and a second portion initialized at a second predetermined time, in accordance with some embodiments;

[0035] FIG. 19 shows example averages of the measurement data shown in FIG. 18, in accordance with some embodiments;

[0036] FIGs. 20A-20C show example fits of the measurement data shown in FIG. 18, in accordance with some embodiments;

[0037] FIG. 21 shows a non-limiting example method of detecting contact between a sensor and liquid, in accordance with some embodiments; and FIG. 22 shows non-limiting example processing circuitry that may be configured to identify a time at which a sensor initially contacts a surface of a liquid, in accordance with some embodiments.

[0038] DETAILED DESCRIPTION

[0039] Techniques for detecting contact between sensors and liquids, associated instruments, associated methods, and associated non-transitory computer-readable media are generally provided. Some techniques described herein are particularly suitable for use in detecting when a probe, inserted into a container holding liquid, initially contacts a surface of the liquid. Some instruments described herein are configured to detect contact between a sensor and a liquid as described herein. Some methods described herein perform detection of contact between a sensor and a liquid as described herein. Some non-transitory computer-readable- media described herein include processor-executable instructions for detecting contact between a sensor and a liquid as described herein.

[0040] In some embodiments, detecting contact between a sensor and liquid provides a precise marker for initiating a measurement of the liquid. Advantageously, this may allow for measurements produced using the sensor to be initialized at an identified time of initial contact between the sensor and liquid. For example, data that at least immediately precedes the time of initial contact, which may not be desirable to include in downstream processing, may be filtered out so as to not add clutter that impedes, e.g., analysis and / or visualizations of the data that begins at the time of initial contact.

[0041] In some embodiments, a probe may be configured to be inserted into a container holding liquid, and a time at which the probe initially contacts a surface of the liquid may be identified based on electrical signals indicating content of an optical signal received from the probe. For example, the optical signal may include light reflected by the end of the probe, which may change when the end of the probe initially contacts the surface of the liquid in a manner that is identifiable based on the electrical signals (e.g., among optical data based thereon). For instance, where the optical signal also includes light reflected by an interface internal to the probe, interference between the light reflected by the end of the probe and the light reflected by the interface internal to the probe may change in an identifiable manner when the probe initially contacts the surface of the liquid.

[0042] In some embodiments, identifying a time at which the probe initially contacts the surface of the liquid may be performed using a processor operatively coupled to memory. For example, an instrument that includes the probe may further include an optical detector configured to receive the optical signal from the detector, and the instrument may further include a processor operatively coupled to memory and configured to receive electrical signals produced over time indicating content of the optical signal. Advantageously, identifying the time of initial probe contact with the surface of the liquid using processing components internal to the instrument allows for filtering out undesired optical data (e.g., indicating the optical signal as received prior to the identified time) prior to outputting measurement data (e.g., for data communication and / or visualization), which may optionally be performed in real-time.

[0043] FIG. 1 shows one non-limiting example of an instrument 100 configured to detect contact between a sensor and a liquid, in accordance with some embodiments.

[0044] As shown in FIG. 1, the instrument 100 includes a probe 110, an optical detector 120, and a processor 130. In some embodiments, the probe 110 may be configured to produce an optical signal 116 that the optical detector 120 may be configured to receive, and the processor 130 may be configured to output measurement data based on electrical signals 122 produced by the optical detector 120 indicating content of the optical signal 116. For example, the processor 130 may be configured to output measurement data indicating the content of the optical signal 116 based on the electrical signals 122.

[0045] In some embodiments, the probe 110 may be configured to transmit light. For example, the probe 110 may include an optical waveguide configured to propagate light, such as using total internal reflection along a length of the probe 110. In FIG. 1, the instrument 100 includes a light source 140 and the probe 110 is configured to receive and transmit light 142 emitted by the light source 140. For example, the instrument 100 may include a cable configured to transmit the light 142 from the light source 140 to the probe 110. In other embodiments, the probe 110 may be configured to transmit light received from an external component (e.g., a light source of a surrounding system that includes and / or interfaces with the instrument 100).

[0046] In some embodiments, the optical detector 120 may be configured to receive the optical signal 116 including light reflected by the probe 110. For example, the optical signal 116 may comprise a first portion Pl of the light reflected by an interface 114 internal to the probe 110 and a second portion P2 of the light reflected by the end 112 of the probe 110. For example, the interface 114 may be a boundary between different materials within the probe 110, such as materials having different refractive indices such that the boundary reflects the transmitted light back down the probe 110. Similarly, the end 112 of the probe may be configured as a boundary between material of the probe 110 and material beyond the end 112 of the probe 110, which may have different refractive indices such that the boundary reflects the transmitted light back down the probe 110. In some embodiments, the optical detector 120 may include a spectrometer configured to produce the electrical signals 122 over time indicating spectral content of the optical signal 116. For example, as described further herein, the portions Pl and P2 may interfere to produce different optical signal intensity over the spectral content of the optical signal 116, which may indicate the relative intensities of the portions Pl and P2.

[0047] In some embodiments, the instrument 100 may further include a cable configured to transmit the optical signal 116 from the probe 110 to the optical detector 120. For example, the cable may include an optical fiber cable configured to propagate the optical signal 116 from the probe 110 to the optical detector 120. For instance, the cable may be included in the instrument 100, and / or may be included in a system that includes or is configured to interface with the instrument 100. In some embodiments, the optical detector 120 may have a port configured to receive a cable from the probe 110 to receive the optical signal 116.

[0048] In some embodiments, the instrument 100 may be configured to insert (or at least capable of inserting) the probe 110 into a container 102 holding liquid 104 at least until an end 112 of the probe 110 initially contacts a surface of the liquid 104. For example, the liquid 104 may include a species to be measured based on the optical signal 116 produced by the probe 110 while the probe end 112 contacts the liquid 104, such as starting from when the probe end 112 initially contacts the liquid surface 106. In FIG. 1, the probe 110 is shown partially inserted into the container 102 with some distance between the probe end 112 and the liquid surface 106, which may be the case as the probe 110 is being inserted into the container 102 prior to the probe end 112 initially contacting the liquid surface 106. In some embodiments, the instrument 100 may include and / or be configured to interface with a motor that is configured to move the probe 110 into the container 102, which may cause the probe 110 to contact the liquid surface 106 as the probe 110 moves into the container. For example, the instrument 100 may be configured to insert the probe end 112 beyond the liquid surface 106 before the probe 110 is held, at least momentarily, in place within the container 102. For instance, the probe 110 may be held within the container 102 with at least some distance between the probe end 112 and a bottom surface of the container 102 to limit the extent of reflections from the bottom surface of the container 102 being present in the optical signal 116.

[0049] In some embodiments, the processor 130 may be operatively coupled to memory and configured to, based on electrical signals 122 produced by the optical detector 120 over time indicating content of the optical signal 116, identify a time at which the probe 110 initially contacts the surface 106 of the liquid 104 during insertion of the probe 110 into the container 102. For example, the processor 130 may be configured to receive optical data, based on the electrical signals 122, indicating the content of the optical signal 116 over time and identify, among the optical data, the time at which the probe end 112 initially contacts the surface 106 of the liquid 104. For instance, the optical data may be received for a time period that begins at least immediately before the time of initial contact and ends at least immediately after the time of initial contact. According to various embodiments, the optical data received by the processor 130 may include the electrical signals 122 (e.g., as shown in FIG. 1 being received by the processor 130) and / or may indicate content of the electrical signals 122 (e.g., which may not be directly received by the processor 130).

[0050] In some embodiments, the processor 130 may be in electrical communication with the optical detector 120 to receive the electrical signals 122 and / or to receive optical data based on the electrical signals 122, the latter of which may be provided by an intermediary component that receives the electrical signals 122. According to various embodiments, the processor 130 and optical detector 120 may be connected directly or indirectly (e.g., via an intermediary component) via traces on a circuit board on which the processor 130 and optical detector 120 are mounted and / or via electrical connectors on circuit boards on which the processor 130 and optical detector 120 are mounted, respectively. According to various embodiments, the processor 130 may include a general-purpose central processing unit (CPU), a graphics processing unit (GPU) (e.g., configured for enhanced parallel processing with respect to some CPUs), and / or an application specific integrated circuit (ASIC) and / or field-programmable gate array (FPGA) configured for digital signal processing. In some embodiments, the processor 130 may be operatively coupled to memory configured to store configuration instructions and / or parameters (e.g., predetermined thresholds and / or settings), e.g., for detecting contact between the probe 110 and the liquid surface 106.

[0051] In some embodiments, the second portion P2 of reflected light, indicated in the optical signal 116 and used at least in part to identify the time of initial contact, may include light reflected by a boundary between the probe end 112 and the liquid surface 106. For example, at the time of initial contact between the probe end 112 and the liquid surface 106, the boundary that produces the second portion P2 of reflected light may be between the material of the probe end 112 and the material of the liquid surface 106, such that the amount of reflected light may depend (e.g., primarily) on differences in refractive index between the material of the probe end 112 and the material of the liquid surface 106. For instance, upon initial contact with the liquid surface 106, the amount of reflected light may change significantly from prior to contact, at which prior time the boundary may be between the material of the probe end 112 and an intervening medium (e.g., air) having a refractive index significantly different from the liquid surface 106.

[0052] In some embodiments, the processor 130 may be configured to identify the time at which the probe end 112 initially contacts the liquid surface 106 based on relative intensities of the first portion Pl of reflected light and the second portion P2 of reflected light indicated in the optical signal 116. For example, relative intensities of the first portion Pl and second portion P2 may be detected based on spectral content of the optical signal 116 matching and / or falling within a predetermined threshold of spectral content associated with the probe end 112 contacting the liquid surface 106. For instance, a spectral profile associated with the probe end 112 contacting the liquid surface 106 may be set based on spectral content of an optical signal 116 received at a previously identified time at which the probe end 112 (and / or another probe end 112 of the instrument 100) initially contacted the liquid surface 106.

[0053] In some embodiments, the processor 130 may be configured to identify the time at which the probe 110 initially contacts the surface 106 of the liquid 104 based on correlation between a first spectral content sample of the optical signal 116 and a second spectral content sample of the optical signal 116, with the time of initial contact being between times of the first spectral content sample and the second spectral content sample. For example, where the optical detector 120 includes a spectrometer, the processor 130 may be configured to receive spectral content samples of the optical signal 116 over time from the spectrometer and crosscorrelate spectral samples, such that relative intensities of the first portion Pl and second portion P2 may be determined from a cross-correlation of spectral content samples as an alternative or in addition to determining the relative intensities from a spectral content sample directly.

[0054] In some embodiments, the processor 130 may be further configured to filter out, from the optical data indicating the content of the optical signal 116 over time, content of the optical signal 116 received by the optical detector 120 prior to the time at which the probe 110 initially contacts the surface 106 of the liquid 104. For example, the processor 130 may be configured to filter out, from the optical data based on the electrical signals 122, optical data corresponding to at least immediately before the time of initial contact between the probe end 112 and the liquid surface 106. For instance, as described further below, the probe 110 may be inserted into the container 102 to contact the liquid 104 after being inserted into liquid held by another container, and the processor 130 may be configured to filter out optical data corresponding to at least some time between when the probe 110 was removed from the liquid held by the other container and the time of initial contact between the probe end 112 and the liquid surface 106.

[0055] In one non-limiting example, spectral content of an optical signal may indicate initial contact between the probe end 112 and liquid surface 106 by exhibiting an increase in brightness over time (e.g., due to increased reflections from the liquid surface 106 as the probe end 112 nears and reaches the liquid surface 106). For instance, cross-correlation over , e.g., 1-3 spectral samples over time may indicate an apparent wavelength shift due to increasing brightness of the optical signal, and such a wavelength shift may be identified by processor 130 as, e.g., exceeding a threshold wavelength shift.

[0056] In some embodiments, the processor 130 may be further configured to receive second optical data indicating content of a second optical signal from the probe 110. For example, the second optical signal may include light reflected by the interface 114 internal to the probe 110 and light reflected by a boundary between the probe end 112 and a species immobilized on the probe (see, e.g., FIG. 5A). For instance, the optical detector 120 may be further configured to receive the second optical signal from the probe 110 and produce second electrical signals over time indicating content of the second optical signal, and the second optical data received by the processor 130 indicating light reflected from the immobilized species may be based on the second electrical signals from the optical detector 120.

[0057] According to various embodiments, the same processor (e.g., one processor 130 or a same subset of processors 130) may be configured to receive the optical data indicating the time of initial contact and the presence of a species immobilized on the probe end 112 (e.g., at and / or after the time of initial contact), respectively, and / or the same optical detector 120 (e.g., one optical detector 120 or a same subset of optical detectors 120) may be configured to produce the electrical signals on which such optical data are based. Alternatively or additionally, separate processors (e.g., of multiple processors 130) may be configured to receive the respective optical data and / or separate optical detectors (e.g., of multiple optical detectors 120) may be configured to produce the respective electrical signals. For instance, the instrument 100 may include a second optical detector (e.g., described in connection with FIG. 10) configured to receive the second optical signal and produce second electrical signals over time indicating content of the second optical signal, with the second optical data received by the processor 130 being based on the second electrical signals.

[0058] FIG. 2 shows one non-limiting example of a system 200 including the instrument 100 of FIG. 1, in accordance with some embodiments. As shown in FIG. 2, the system 200 further includes a controller 210, a light source 220, a motor 230, a cable 240, a display 250, and a data communication interface 260. For example, the controller 210 may be configured to operate the light source 220 to transmit light to the probe 110 and / or to operate the motor 230 to insert the probe 110 into a container (e.g., 102 in FIG. 1). For instance, the controller 210 may include a processor (e.g., as described herein for processor 130). In the same or another example, the cable 240 may be configured to transmit an optical signal (e.g., 116) from the probe 110 to the optical detector 120. In FIG. 2, the light source 220 and the cable 240 are part of the system 200 that includes the instrument 100, though in other embodiments the instrument 100 may alternatively or additionally include a light source and / or cable.

[0059] In some embodiments, the instrument 100 may be further configured to output, to a user interface and / or via a data communication interface, measurement data 132 indicating the content of an optical signal (e.g., 116), with the measurement data 132 being initialized at the time at which the probe 110 initially contacts a liquid surface (e.g., 106). For example, in FIG. 2, the processor 130 of the instrument 100 is shown configured to output the measurement data 132 to the controller 210, which in turn may be configured to output the measurement data 132 to the display 250 for displaying to a user (e.g., in a user interface displayed on the display 250) and / or to the data communication interface 260 (e.g., a universal serial bus (USB)). For instance, the measurement data 132 may omit data from prior to the time of initial contact, which may reduce clutter when visualized on the display 250 and / or when processed downstream by a device that receives the measurement data 132 via the data communication interface 260.

[0060] FIGs. 3A-3D show one non-limiting example sequence of inserting probes 310 of an instrument 300 into respective containers 302 holding liquid 304, in accordance with some embodiments.

[0061] In some embodiments, the instrument 300 may be configured as described herein for the instrument 100, such as including the probes 310, which may be configured as described herein for the probe 110. As further shown in FIGs. 3A-3D, the probes 310 include probe waveguides 314 terminating at the probe ends 312. For example, each probe waveguide 314 may include optical waveguides configured to propagate light toward the container respective container 302 and / or to propagate an optical signal (e.g., including light reflected from the probe end 312 and from an interface internal to the probe 310) to an optical detector (e.g., 120) of the instrument 300. In the sequence shown in FIGs. 3A-3D, the probes 310 are inserted into the containers 302 along an insertion direction I. For example, a motor (e.g., 230) of the instrument 300 and / or of a system (e.g., 200) that includes the instrument 300 may be configured to move (or at least capable of moving) the probes 310 along the insertion direction I to insert the probes 310 into the containers 302. It should be appreciated that insertion of the probes 310 into the containers 302 might alternatively or additionally be achieved by moving the containers 302 relative to the probes 310, as embodiments described herein are not so limited.

[0062] As shown in FIG. 3A, the probes 310 are suspended above the containers 302 in the insertion direction I with none of the probe ends 312 in contact with a surface 306 of the liquid 304 held by the respective containers 302. For example, optical signals received from each probe 310 as shown in FIG. 3 A may not indicate contact between any of the probes 310 and the liquid 304. For instance, due to lack of contact between the probes 310 and the liquid 304, optical signals received from the probes 310 at the positions shown in FIG. 3A may produce data that are undesired for visualization and / or analysis, such as due to the inclusion in the optical signal of light received at the probe 310 from the surrounding environment. In some embodiments, the positions of the probes 310 as shown in FIG. 3A may be starting positions from which the probes 310 may be inserted along the insertion direction I into the respective containers 302. It should be appreciated that, as described further below, the probes 310 may have been removed from other containers (not shown) prior to reaching their positions as shown in FIG. 3A.

[0063] In FIG. 3B, the probes 310 have been partially inserted into the containers 302 in the insertion direction I to the point at which one of the probe ends 312 initially contacts the liquid surface 306 in the respective container 302. For example, as shown in FIG. 3B, the probe 310 whose probe end 312 contacts the liquid surface 306 may provide an optical signal indicating (e.g., to the processor 130) that the probe end 312 initially contacts the liquid surface 306, though the other probes 310 may provide optical signals that do not indicate contact between the probe end 312 and the liquid surface 306. In the illustrated embodiment, the probe ends 312 do not initially contact the respective liquid surfaces 306 due to different heights of the liquid 304 in the respective containers 302 along the insertion direction I, which may occur, e.g., in a laboratory environment where control over the amount of liquid 304 in each container 302 may be unduly difficult to finely control. In other embodiments, however, the liquid surfaces 306 may be substantially the same in height along the insertion direction I, in which case each probe end 312 may initially contact the respective liquid surface 306 at substantially the same time. In FIG. 3C, the probes 310 have been inserted farther into the containers 302 along the insertion direction I such that each probe end 312 contacts the respective liquid surface 306, with the probe end 312 that contacts the lowest liquid surface 306 in the insertion direction I initially contacting the liquid surface 306. For example, as shown in FIG. 3C, each probe 310 may provide an optical signal indicating (e.g., to the processor 130) that the probe end 312 contacts the liquid 304. In the illustrated embodiment, the other three probes 310 are inserted beyond the liquid surface 306 in the insertion direction I.

[0064] In FIG. 3D, the probe ends 312 are submerged in the liquid 304 in the respective containers 302, such that optical signals provided by the probes 310 (e.g., to the processor 130) may indicate characteristics of the liquid 304 (e.g., a species therein immobilized to the probe end 312). In FIG. 3D, the probes 310 have been inserted to substantially the same position along the insertion direction I such that each probe end 312 is spaced substantially the same distance from the bottom surface of the respective container 302. In some embodiments, the probes 310 may remain at the position shown in FIG. 3D until they are removed from the containers 302 (e.g., by being moved the opposite direction as insertion along the insertion direction I). For example, the probes 310 may remain at the positions shown in FIG. 3D for about one minute, depending on the type of measurement and / or the type of binding to the probe ends 312 being measured.

[0065] According to various embodiments, a processor (e.g., 130) of the instrument 300 may be configured to identify a time at which a probe end 312 initially contacts a liquid surface 306 by identifying a time at which a probe end 312 initially contacts a liquid surface 306 regardless of whether other probe ends 312 contact respective liquid surfaces 306 (e.g., FIG. 3B) and / or by identifying a time at which a probe end 312 initially contacts a liquid surface 306 and each other probe end 312 also contacts a respective liquid surface 306 (e.g., FIG. 3C). Appropriate criteria for identifying a time of initial contact with the liquid surface 306 may be selected depending on the needs of the particular application. For example, identifying a time at which a probe end 312 initially contacts a respective liquid surface 306 regardless of other probe ends 312 (e.g., FIG. 3B) may ensure measurement data for the probe 310 that contacts the liquid surface 306 are not omitted. On the other hand, identifying a time at which a probe end 312 initially contacts a liquid surface 306 and each other probe end 312 also contacts a respective liquid surface 306 may ensure that data for probes 310 that have not yet initially contacted a respective liquid surface 306 are omitted.

[0066] In some embodiments, the probes 310 may be further configured to be (or at least capable of being) moved by the instrument 300 between the containers 302 and other containers holding a second liquid. For example, prior to or after insertion of the probes 310 into the containers 302 as shown in FIGs. 3A-3D, the instrument 300 (and / or a system that includes the instrument) may be configured to translate the probes (e.g., in a translation direction transverse and / or orthogonal to the insertion direction I) toward other containers for insertion. For instance, insertion of the probes 310 into the liquid 304 in the containers 302 as shown in FIG. 3A-3D may bind species to the probe ends 312, and translating the probes 310 to other containers holding liquid and inserting the probe ends 312 into the other containers to contact the liquid may disassociate the species that were bound to the probe ends 312. In the same or another example, insertion of the probes 310 into the liquid 304 in the containers 302 as shown in FIGs. 3A-3D may disassociate species from the probe ends 312 that were bound to the probe ends 312 when inserted into other containers prior to translating the probes 310 towards and inserting the probes 310 into the containers 302. In other embodiments, the instrument 300 (and / or system that includes the instrument) may be configured only to insert the probes 310 into the containers 302, as embodiments described herein are not so limited.

[0067] In some embodiments, an optical detector (e.g., 120) of the instrument 300 may be further configured to receive a third optical signal from a probe 310, including light reflected by an interface internal to the probe 310 and light reflected by the probe end 312, and a processor (e.g., 130) of the instrument 300 may be further configured to, based on electrical signals produced by the optical detector over time indicating content of the third optical signal, identify a second time at which the probe 310 initially contacts a surface of the second liquid. For example, identification of the second time may be performed in the manner described herein for identifying a time of initial contact with a liquid surface.

[0068] In FIGs. 3A-3D, the containers 302 are shown connected to one another to form a containing member having a plurality of containers 302. In other embodiments, a plurality of separate containers 302 may be used.

[0069] In FIGs. 3A-3D, the instrument 300 includes a probe 310 for each container 302, though it should be appreciated that any number of probes 310 and / or containers 302 may be included. For example, a smaller number of probes 310 may be translated among a larger number of containers 302 over time, such as described further below. Alternatively or additionally, only a single probe 310 may be included in the instrument 300.

[0070] FIG. 4A shows a non-limiting example of an optical signal including a first portion of transmitted light reflected from an interface 414 internal to a probe 410 and a second portion of transmitted light reflected from an end 412 of the probe 410, in accordance with some embodiments. In some embodiments, the probe 410 may be configured to transmit light and to reflect light from the interface 414 and from the probe end 412, such as described herein for the probe 110.

[0071] FIG. 4B shows a non-limiting example of relative light intensity vs. wavelength for the optical signal of FIG. 4A, in accordance with some embodiments.

[0072] In some embodiments, the probe 410 may be configured to transmit broadband light and produce an optical signal including reflected portions of light that interfere to produce different relative intensities over the spectrum with respect to the transmitted light. For example, in FIG. 4A, the probe 410 is shown transmitting white light, whereas FIG. 4B shows the resulting optical signal having non-uniform intensity over the spectrum due to interference between the portions of reflected light. For instance, the relative intensities at various wavelengths over the spectrum may provide an indication of presence or absence of a particular species (e.g., a bound species and / or a liquid surface), the amount of a particular species, and / or the identity of a species at the probe end 412. In some embodiments, the probe 410 may be configured as a biolayer interferometry (BLI) probe.

[0073] FIG. 5A shows a non-limiting example of an optical signal including a first portion of transmitted light reflected from the interface 414 internal to the probe 410 and a second portion of transmitted light reflected from the end 412 of the probe 410 having a species 420 immobilized thereon, in accordance with some embodiments.

[0074] As shown in FIG. 5 A, a species 420 is bound to the probe end 412, such as may occur when the probe end 412 is treated with a binding entity and inserted into liquid including the species 420.

[0075] FIG. 5B shows a non-limiting example of relative light intensity vs. wavelength for the optical signal of FIG. 5A, in accordance with some embodiments.

[0076] As shown in FIG. 5B, the relative intensities of the optical signal over the spectrum are different with respect to the optical signal of FIG. 4B, such as due to the impact of the bound species 420 on the amount of light reflected from the probe end 412 in the optical signal of FIG. 4B as compared to the optical signal of FIG. 4A in which no species 420 is bound.

[0077] While FIGs. 4A-5B use the example of a species bound to the probe end 412 resulting in interference that produces different relative intensities over the spectrum of an optical signal, it should be appreciated that interference patterns may occur when a probe (e.g., 410) initially contacts a liquid surface that may be similarly detectable by a processor (e.g., 130). FIGs. 6A and 6B show a non-limiting example of a fiber bundle 620 coupled to a probe 610 that may be included in an instrument or system described herein, in accordance with some embodiments.

[0078] In some embodiments, the probe 610 may be configured as described herein for the probe 110, 310, and / or 410. For example, the probe 610 is shown including a probe end 612, probe internal interface 614, and probe waveguide 618.

[0079] As shown in FIG. 6A, the fiber bundle 620 includes a coupling end 622 that is coupled to a coupling end 616 of the probe 610. For example, when coupled, optical waveguides of the fiber bundle 620 and the probe 610 may be aligned for coupling light therebetween. For instance, the fiber bundle coupling end 622 may include a threaded male SMA connector and the probe coupling end 622 may include a threaded female SMA connector.

[0080] As shown in FIG. 6B, the fiber bundle 620 may include a light source fiber 624 configured to transmit light (e.g., 142) to the probe 610 from a light source (e.g., 140, 220) and a reflected light fiber 626 configured to transmit an optical signal (e.g., 116) from the probe 610 to an optical detector (e.g., 120). For example, the probe 610 may be configured to couple the optical signal (e.g., 116) to both the light source fiber 624 and the reflected light fiber 626, though only the reflected light fiber 626 may be configured to transmit the optical signal to an optical detector.

[0081] FIGs. 7A and 7B show a non-limiting example of a fiber bundle 720 that may be included in an instrument or system described herein, in accordance with some embodiments.

[0082] In some embodiments, the fiber bundle 720 may be configured as described herein for the fiber bundle 620. For example, in FIG. 7A, the fiber bundle 720 includes a light source fiber 724 and a reflected light fiber 726 terminating at a fiber bundle coupling end 722.

[0083] FIG. 7B shows the fiber bundle 720 at the coupling end 722 from the perspective of a coupling end (e.g., 622) of a probe (e.g., 610). As shown in FIG. 7B, light source fibers 724 are disposed around the reflected light fiber 726 in a ring. For example, the light source fibers 724 as shown in FIG. 7A may be disposed within a cable from which the light source fibers 724 are separated and positioned around the reflected light fiber 724 within the fiber bundle 720.

[0084] FIG. 8 shows a non-limiting example of the fiber bundle 720 with coupling end 722 removed, in accordance with some embodiments. As shown in FIG. 8, the light source fibers 724 and reflected light fiber 726 are elongated parallel to one another. FIG. 9 shows a non-limiting example of a cable configuration 900 for transmitting light to and receiving optical signals from a plurality of probes, in accordance with some embodiments.

[0085] As shown in FIG. 9, the cable configuration 900 includes a plurality of fiber bundles 920, which may be configured as described herein for the fiber bundles 620 and / or 720, such as including fiber bundle coupling ends 922 configured for coupling to a plurality of probes (not shown), light source fibers 924, and reflected light fibers 926. Also shown in FIG. 9, the fiber bundles 920 include reflected light coupling ends 928, which may be configured for coupling to an optical detector (not shown). For example, the light source fibers 924 are shown terminating at a light source coupling end 930 to receive light from the light source (not shown) and the reflected light fibers 926 are shown terminating in the reflected light coupling ends 928 to provide optical signals from the probes.

[0086] FIG. 10 shows an alternative non-limiting example of a cable configuration 1000 for transmitting light to and receiving optical signals from a plurality of probes, in accordance with some embodiments.

[0087] As shown in FIG. 10, the cable configuration 1000 includes a plurality of fiber bundles 1020 that may be configured as described herein for fiber bundles 920. For example, the fiber bundles 920 include fiber bundle coupling ends 1022, light source fibers 1024 that run from the fiber bundle coupling ends 1022 to a light source coupling end 1030, and reflected light fibers 1026 that run from the fiber bundle coupling ends 1022 to reflected light coupling ends 1028.

[0088] In some embodiments, an instrument described herein may include an optical detector (e.g., 120) configured to receive an optical signal (e.g., 116) from a probe (e.g., 110) indicating content of light reflected from the probe, and may further include an auxiliary optical detector configured to receive the optical signal. For example, the optical detector may be configured to produce electrical signals indicating, e.g., characteristics of a species immobilized to the end (e.g., 112) of the probe for analysis and characterization, whereas the auxiliary optical detector may be configured to produce electrical signals indicating initial contact between the probe end and a liquid surface. In some embodiments, an auxiliary optical detector may be selected that is suited to indicate initial contact between a probe end and a liquid surface even though the auxiliary optical detector may not be well suited to indicate characteristics of a species immobilized to the probe end.

[0089] As shown in FIG. 10, the fiber bundles 1020 further include an auxiliary reflected light fiber 1026’ running from the fiber bundles 1020 to an auxiliary reflected light coupling end 1028’. For example, the auxiliary reflected light fiber 1026’ may take the place of one of the light source fibers (e.g., 724) that may be positioned around the reflected light fiber 1026 in the configuration shown in FIGs. 7A-8. In some embodiments, the auxiliary reflected light fiber 1026’ and the auxiliary reflected light coupling end 1028’ may be configured in the manner described herein for the reflected light fibers 1026 and reflected light fiber coupling ends 1028. In the illustrated embodiment, only one fiber bundle 1020 is shown including the auxiliary reflected light fiber 1026’, though it should be appreciated that any number of the fiber bundles 1020 up to all of the fiber bundles 1020 may include an auxiliary reflected light fiber 1026’.

[0090] FIG. 11 shows a first non-limiting example of measurement data initialized at a time at which a probe initially contacts a surface of a liquid, in accordance with some embodiments.

[0091] As shown in FIG. 11, two measurement data traces are plotted on a time axis with the measurement data initialized at the time of 0 seconds. For example, as shown in FIG. 11, the highlighted data show an increase in detected wavelength shift between cross-correlated spectral samples at initialization following over 20 seconds of substantially no wavelength shift, which may indicate an increase in thickness of material buildup at the end of the probe starting at initialization after over 20 seconds of substantially no material buildup. For instance, data obtained based on optical signals from the probes in between the data shown at 0 seconds and the preceding data may be omitted from the illustrated measurement data as filtered out (e.g., by the processor 130) by occurring before initial probe end contact with a liquid surface.

[0092] In some embodiments, when the probe initially contacts the liquid surface at 0 seconds, material (e.g., a species) in the liquid may begin to bind to the probe end. In the illustrated example, the two data traces may correspond to two probes, and initialization may occur at the time of initial liquid surface contact of the probe end of the latter of the two probes to contact a liquid surface.

[0093] In the measurement data in FIG. 11, the probes were inserted into containers of a plate including 384 containers with the containers having tilted bottom surfaces.

[0094] FIG. 12 shows a second non-limiting example of measurement data initialized at a time at which a probe initially contacts a surface of a liquid, in accordance with some embodiments.

[0095] As shown in FIG. 12, two measurement data traces are plotted on a time axis with the measurement data initialized at the time of 0 seconds as in FIG. 11. In the measurement data in FIG. 12, the probes were inserted into containers of a plate including 96 containers with the containers having flat bottom surfaces.

[0096] FIG. 13 shows a third non-limiting example of measurement data initialized at a time at which a probe initially contacts a surface of a liquid, in accordance with some embodiments.

[0097] The measurement data shown in FIG. 13 correspond to the same measurement as in FIG. 12, except that a lower optical sampling rate (5 Hz) was used in the optical detector as compared to FIG. 12 (58.8 Hz). Consequently, the data have lower resolution with respect to time and some measurement data occurring immediately after initial contact between the probe end and liquid surface are omitted, such as due to delays between the initial contact and the processing of an optical signal sample that indicates the initial contact.

[0098] FIG. 14 shows an example of measurement data initialized at a predetermined time, in accordance with some embodiments.

[0099] The measurement data shown in FIG. 14 correspond to the same measurement as in FIG. 13 using the same optical sampling rate, except that the measurement data are initialized at a predetermined time that occurs after the probes have been inserted at least a predetermined distance into the containers, such that the probe ends are expected to have already contacted the liquid surface. Consequently, the data omits some measurement data occurring immediately after initial contact between the probe end and liquid surface and before the predetermined time.

[0100] FIG. 15 shows a non-limiting example of measurement data including a first portion initialized at a first time at which a probe initially contacts a surface of a first liquid and a second portion initialized at a second time at which the probe initially contacts a surface of a second liquid, in accordance with some embodiments.

[0101] The measurement data traces shown in FIG. 15 correspond to a plurality of probes, respectively, which were inserted into first containers holding liquid, removed from the first containers, translated to second containers holding liquid, and then inserted into the second containers. The illustrated measurement data are first initialized at 0 seconds, which is the last time of initial liquid contact of any of the probe ends in the first containers, and then the data are re-initialized at 60 seconds, which is the last time of initial liquid contact of any of the probe ends in the second containers. Measurement data are omitted for time between removal of the probe from the first container and re-initialization, including some measurement data from when the probe was still in contact with liquid held by the first container. The measurement data shown in FIG. 15 were obtained using an optical sample rate of 40 Hz.

[0102] The measurement shown in FIG. 15 is methanesulfonamide detection using phosphate-buffered saline (PBS) with 0.5% dimethylsulfoxide (DMSO) as a buffer, 2-fold dilution, and a small molecule lower limit of 95 daltons (Da).

[0103] FIG. 16 shows non-limiting example averages of the measurement data shown in FIG. 15, in accordance with some embodiments.

[0104] FIGs. 17A-17C show non-limiting example fits of the measurement data shown in FIG. 15, in accordance with some embodiments.

[0105] FIG. 18 shows an example of measurement data including a first portion initialized at a first predetermined time and a second portion initialized at a second predetermined time, in accordance with some embodiments.

[0106] The measurement data shown in FIG. 18 correspond to the same measurement as in FIG. 15 except that an optical sample rate of 5 Hz was used.

[0107] FIG. 19 shows example averages of the measurement data shown in FIG. 18, in accordance with some embodiments.

[0108] FIGs. 20A-20C show example fits of the measurement data shown in FIG. 18, in accordance with some embodiments.

[0109] FIG. 21 shows a non-limiting example method 2100 of detecting contact between a sensor and liquid, in accordance with some embodiments.

[0110] In some embodiments, method 2100 may be performed using an instrument described herein, such as instrument 100. For example, method 2100 is shown in FIG. 21 including a step 2102 of transmitting light, a step 2104 of receiving an optical signal, and a step 2106 of identifying a time of initial contact. For example, step 2102 may include a probe (e.g., 110) transmitting light, step 2104 may include an optical detector (e.g., 120) receiving the optical signal from the probe, and step 2106 may include a processor (e.g., 130) identifying, based on electrical signals produced by the optical detector over time indicating content of the optical signal, a time at which the probe initially contacts a liquid surface during insertion of the probe into a container holding liquid. For instance, these steps may be performed as has been described herein for instruments and / or systems that include instruments.

[0111] FIG. 22 shows a non-limiting example processing circuitry 2200 that may be configured to identify a time at which a sensor initially contacts a surface of a liquid, in accordance with some embodiments. In some embodiments, identifying a time at which a sensor initially contacts a surface of a liquid as described herein may be performed using processing circuitry 2200 (e.g., implemented using components mounted on and / or coupled to a substrate of an instrument). Processing circuitry 2200 may include one or more processors 2202 and one or more articles of manufacture that comprise non-transitory computer-readable storage media (e.g., memory 2204 and one or more non-volatile storage media 2206). The processor 2202 may control writing data to and reading data from the memory 2204 and the non-volatile storage device 2206 in any suitable manner, as the aspects of the disclosure provided herein are not limited in this respect. To perform any of the functionality described herein, the processor 2202 may execute one or more processor-executable instructions stored in one or more non-transitory computer-readable storage media (e.g., the memory 2204), which may serve as non-transitory computer-readable storage media storing processor-executable instructions for execution by the processor 2202.

[0112] In some embodiments, any method or method steps described herein as being performed by a processor may be stored as processor-executable instructions in non- transitory computer-readable media. For example, where processing steps to be executed by a processor are based on or in response to received data or signals (e.g., from an optical detector), the instructions may specify a format and / or type of content of the received data or signals designating those data or signals as the subject of the processing steps.

[0113] While several embodiments of the present disclosure 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 disclosure. 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 disclosure 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 disclosure 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 disclosure may be practiced otherwise than as specifically described and claimed. The present disclosure 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 disclosure.

[0114] 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.

[0115] 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.”

[0116] 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.

[0117] 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.

[0118] 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.

[0119] 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.

[0120] 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 instrument, comprising: a probe configured to transmit light, wherein the instrument is configured to insert the probe into a container holding liquid at least until an end of the probe initially contacts a surface of the liquid; an optical detector configured to receive an optical signal from the probe, the optical signal comprising: a first portion of the light reflected by an interface internal to the probe; and a second portion of the light reflected by the end of the probe; and a processor operatively coupled to memory and configured to, based on electrical signals produced by the optical detector over time indicating content of the optical signal, identify a time at which the probe initially contacts the surface of the liquid during insertion of the probe into the container.

2. The instrument of claim 1, wherein the probe comprises an optical waveguide configured to propagate the light toward the container and to propagate the optical signal to the optical detector.

3. The instrument of claim 1, wherein the processor is further configured to: receive optical data indicating the content of the optical signal over time, the optical data being based on the electrical signals; and identify, among the optical data, the time at which the probe initially contacts the surface of the liquid.

4. The instrument of claim 3, wherein the processor is further configured to filter out, from the optical data indicating the content of the optical signal over time, content of the optical signal received by the optical detector prior to the time at which the probe initially contacts the surface of the liquid.

5. The instrument of claim 1, wherein: the instrument is further configured to output, to a user interface and / or via a data communication interface, measurement data indicating the content of the optical signal; and the measurement data are initialized at the time at which the probe initially contacts the surface of the liquid.

6. The instrument of claim 1, wherein the optical detector comprises a spectrometer, and the electrical signals are produced by the spectrometer over time indicating spectral content of the optical signal.

7. The instrument of claim 1, further comprising: a light source configured to emit the light; a first cable configured to transmit the light to the probe; and a second cable configured to transmit the optical signal from the probe to the optical detector.

8. The instrument of claim 1, wherein: the second portion of the light comprises light reflected by a boundary between the end of the probe and the surface of the liquid.

9. The instrument of claim 1, wherein the processor is further configured to receive second optical data indicating content of a second optical signal from the probe, the second optical signal comprising: light reflected by the interface internal to the probe; and light reflected by a boundary between the end of the probe and a species immobilized on the probe.

10. The instrument of claim 9, wherein: the optical detector is further configured to receive the second optical signal and produce second electrical signals over time indicating content of the second optical signal; and the second optical data are based on the second electrical signals.

11. The instrument of claim 9, further comprising: a second optical detector configured to receive the second optical signal and produce second electrical signals over time indicating content of the second optical signal, wherein the second optical data are based on the second electrical signals.

12. The instrument of claim 1, wherein:the probe is further configured to be moved by the instrument between the container and a second container holding a second liquid; the optical detector is further configured to receive a third optical signal from the probe, the third optical signal comprising: light reflected by the interface internal to the probe; and light reflected by the end of the probe; and the processor is further configured to, based on electrical signals produced by the optical detector over time indicating content of the third optical signal, identify a second time at which the probe initially contacts a surface of the second liquid.

13. A method, comprising: transmitting, by a probe of an instrument, light, wherein the probe is inserted into a container holding a liquid at least until an end of the probe initially contacts a surface of the liquid; receiving, by an optical detector of the instrument, an optical signal from the probe, the optical signal comprising: a first portion of the light reflected by an interface internal to the probe; and a second portion of the light reflected by the end of the probe; and identifying, by a processor of the instrument that is operatively coupled to memory of the instrument, based on electrical signals produced by the optical detector over time indicating content of the optical signal, a time at which the probe initially contacts the surface of the liquid during insertion of the probe into the container.

14. The method of claim 13, further comprising: propagating, by an optical waveguide of the probe, the light toward the container; and propagating, by the optical waveguide, the optical signal to the optical detector.

15. The method of claim 13, further comprising: receiving, by the processor, optical data indicating the content of the optical signal over time, the optical data being based on the electrical signals, wherein identifying the time at which the probe initially contacts the surface of the liquid is among the optical data.

16. The method of claim 15, further comprising filtering out, by the processor, from the optical data indicating the content of the optical signal over time, content of the optical signal received by the optical detector prior to the time at which the probe initially contacts the surface of the liquid.

17. The method of claim 13, further comprising: outputting, by the instrument, to a user interface and / or via a data communication interface, measurement data indicating the content of the optical signal, wherein the measurement data are initialized at the time at which the probe initially contacts the surface of the liquid.

18. The method of claim 13, wherein the optical detector comprises a spectrometer, and the electrical signals are produced by the spectrometer over time indicating spectral content of the optical signal.

19. The method of claim 13, further comprising: emitting, by a light source of the instrument, the light; transmitting, by a first cable of the instrument, the light to the probe; and transmitting, by a second cable of the instrument, the optical signal from the probe to the optical detector.

20. The method of claim 13, wherein: the second portion of the light comprises light reflected by a boundary between the end of the probe and the surface of the liquid.

21. The method of claim 13, further comprising receiving, by the processor, second optical data indicating content of a second optical signal from the probe, the second optical signal comprising: light reflected by the interface internal to the probe; and light reflected by a boundary between the end of the probe and a species immobilized on the probe.

22. The method of claim 21, further comprising:producing, by the optical detector, second electrical signals over time indicating content of the second optical signal, wherein the second optical data are based on the second electrical signals.

23. The method of claim 21, further comprising: producing, by a second optical detector of the instrument, second electrical signals over time indicating content of the second optical signal, wherein the second optical data are based on the second electrical signals.

24. The method of claim 13, further comprising: moving, by the instrument, the probe between the container and a second container holding a second liquid; receiving, by the optical detector, a third optical signal from the probe, the third optical signal comprising: light reflected by the interface internal to the probe; and light reflected by the end of the probe; and identifying, by the processor, based on electrical signals produced by the optical detector over time indicating content of the third optical signal, a second time at which the probe initially contacts a surface of the second liquid.

25. A non-transitory computer-readable medium having instructions stored thereon that, when executed by a processor, cause the processor to perform a method, the method comprising: identifying, based on electrical signals produced by an optical detector of an instrument over time indicating content of an optical signal, a time at which a probe of the instrument initially contacts a surface of a liquid during insertion of the probe into a container holding the liquid, wherein the probe transmits light, the optical detector receives the optical signal from the probe as the probe is inserted into the container at least until an end of the probe initially contacts the surface of the liquid, and the optical signal comprises: a first portion of the light reflected by an interface internal to the probe; and a second portion of the light reflected by the end of the probe.

26. The non-transitory computer-readable medium of claim 25, wherein the method further comprises: receiving optical data indicating the content of the optical signal over time, the optical data being based on the electrical signals, wherein identifying the time at which the probe initially contacts the surface of the liquid is among the optical data.

27. The non-transitory computer-readable medium of claim 26, wherein the method further comprises filtering out, from the optical data indicating the content of the optical signal over time, content of the optical signal received by the optical detector prior to the time at which the probe initially contacts the surface of the liquid.

28. The non-transitory computer-readable medium of claim 25, wherein the method further comprises: outputting, to a user interface and / or via a data communication interface, measurement data indicating the content of the optical signal, wherein the measurement data are initialized at the time at which the probe initially contacts the surface of the liquid.

29. The non-transitory computer-readable medium of claim 28, wherein: probe is moved from a second container holding a second liquid to the container; and the measurement data omit indication of content of the optical signal between when the probe is removed from the second container and the time at which the probe initially contacts the surface of the liquid.

30. The non-transitory computer-readable medium of claim 25, wherein the optical detector comprises a spectrometer, and the electrical signals are produced by the spectrometer over time indicating spectral content of the optical signal.

31. The non-transitory computer-readable medium of claim 30, wherein identifying the time at which the probe initially contacts the surface of the liquid is based on relative intensities of the first portion of the light and the second portion of the light.

32. The non-transitory computer-readable medium of claim 30, wherein identifying the time at which the probe initially contacts the surface of the liquid is based on correlation between a first spectral content sample of the optical signal and a second spectral content sample of the optical signal, the time being between times of the first spectral content sample and the second spectral content sample.

33. The non-transitory computer-readable medium of claim 25, wherein the method further comprises receiving second optical data indicating content of a second optical signal from the probe, the second optical signal comprising: light reflected by the interface internal to the probe; and light reflected by a boundary between the end of the probe and a species immobilized on the probe.

34. The non-transitory computer-readable medium of claim 33, wherein the second optical data are based on second electrical signals produced by the optical detector over time indicating content of the second optical signal.

35. The non-transitory computer-readable medium of claim 33, wherein the second optical data are based on second electrical signals produced by a second optical detector of the instrument over time indicating content of the second optical signal.

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