Apparatus, system and method for measuring a property of a sample

Abstract

To measure characteristics of a sample, and in particular, to more accurately evaluate optical characteristics of a biological sample containing microorganism particles such as bacteria.SOLUTION: An apparatus comprising an optical instrument (2) for monitoring bacterial growth in a liquid biological sample to which a drug has been administered. The optical instrument 2 comprises a light source 22 that, in use, illuminates the sample along an incident beam axis that intersects at least one of the sample containers, and a light collection arrangement 24 configured to collect light that has been scattered in a forward direction by bacteria in the sample and to direct the collected scattered light to a first photodetector 26, and to prevent unscattered light travelling parallel to the incident beam axis from reaching the first photodetector 26. Based on the intensity of the scattered light received by the first photodetector 26, a representative amount or change in concentration of bacteria present in the sample as a function of time is determined, and a corresponding susceptibility of the bacteria in the sample to the respective drug is determined.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to devices, apparatus, systems and methods for measuring properties of a sample, and in particular for measuring optical properties of biological samples containing microbial particles such as bacteria. [Background technology]

[0002] Many techniques are known for measuring sample properties, and in particular for measuring the optical properties of biological samples, such as the concentration of particles within the sample. For example, absorption spectrophotometers measure the relative absorbance of a sample, while scattering spectrophotometers, flow cytometers, and nephelometers measure the light scattered by the particles in the sample.

[0003] A practical application of such measurements is in the processing and analysis of clinical samples (such as urine, blood, etc.) in situations where the amount and / or type of bacteria present in a given sample must be determined in order to ascertain the most appropriate mode of treatment for a patient / subject (e.g., the type and dosage of antibiotic that must be administered). For example, measuring the time-dependent bacterial concentration of a clinical sample to which a particular drug or antibiotic has already been administered allows one to determine the bacterial susceptibility with respect to that drug (and thus the efficacy of that drug in relation to the particular bacterial strain present in the sample).

[0004] Various systems using such techniques are known for these practical applications, for example WO 2016 / 128747 incorporates the use of an integrating sphere collector into which the clinical sample to be analyzed (drug-dosed) is placed. When the sample is illuminated, bacteria present in the sample scatter some light, which is reflected and diffused by the reflective inner surface of the integrating sphere. WO 2019 / 166799 describes a similar system comprising a pair of optically coupled chambers that uses an integrating light collection mechanism to detect the light scattered by the sample. WO 2018 / 091922 describes a combined cartridge in which a clinical sample can be first cultured to increase the concentration of the bacteria present in the sample; separate portions of the sample are later combined with a variety of different drugs / antibiotics, and the optical properties of each individual sample portion are measured to determine bacterial susceptibility to each drug.

[0005] It is against this background that the devices / instruments, systems and methods of the present invention are conceived. Summary of the Invention

[0006] According to an aspect of the present disclosure, there is provided an optical instrument / device for monitoring bacterial growth in a medicated liquid biological sample and for measuring the amount or concentration of said bacteria, the optical instrument / device comprising: a light source configured, in use, to emit light along an incident beam axis that intersects with a detection chamber of a sample container containing the medicated sample and to illuminate the medicated sample contained within the detection chamber; a first photodetector configured to receive light scattered by particles in the sample; and a second photodetector configured to collect light exiting the detection chamber that has been scattered in a forward direction by particles in the sample within a scattering angle range of about ±4 degrees to ±20 degrees relative to the incident beam axis. and a light collection arrangement configured to direct forward scattered light received by the first photodetector and to block unscattered light traveling parallel to the incident beam axis and exiting the detection chamber from reaching the first photodetector; and at least one processor configured to measure the intensity of the scattered light received by the first photodetector, determine a corresponding representative amount or concentration of particles present in the sample based on the intensity of the scattered light, repeat the measuring and determining steps at a series of predetermined intervals to determine a change in the representative amount or concentration of particles present in the sample as a function of time, and determine a corresponding change in the amount or concentration of particles in the sample. Preferably, the particles in the sample are bacteria, and the change in the representative amount or concentration of particles as a function of time indicates the susceptibility of the bacteria in the sample to a drug / antibiotic. In some embodiments, forward scattered light can be measured within a scattering angle range of about ±5 degrees to ±20 degrees relative to the incident beam axis.

[0007] Beneficially, because this light is scattered primarily over relatively small scattering angles, such as those described above, the devices of the present disclosure can capture a large portion (e.g., about 95%) of the forward scattered light generated by the interaction of the incident light beam with the particles in the sample. As such, the devices of the present disclosure maximize the amount of scattered light intensity that can be collected from a single sample, which also means that a relatively small sample volume can be used to still obtain statistically significant results, particularly related to changes in the scattered light intensity over time.

[0008] In embodiments of this aspect of the present disclosure, the amount or concentration of particles / bacteria is measured quantitatively. In other embodiments, the amount or concentration of particles / bacteria is suitably measured qualitatively, i.e., such that the relative amount or concentration is measured as a function of time; such qualitative measurements may be suitable for and advantageous for simplifying data processing, since changes in particle / bacteria amount or concentration can generally be assessed with a high degree of confidence for other time points and assays. In any of the embodiments of this aspect of the present disclosure, the optical instrument is configured to receive a sample vessel containing at least one detection chamber for receiving a biological sample. The biological sample may potentially contain pathogenic bacteria.

[0009] In some embodiments, the first photodetector may be used in conjunction with a lock-in amplifier to isolate a received signal having a specific frequency, the frequency corresponding to the modulation frequency of the light emitted from the light source. Advantageously, this allows noise signals from other frequencies to be filtered out, thereby improving the signal-to-noise ratio of the resulting signal.

[0010] Suitably, the collection arrangement is configured so that only forward scattered light within an angular range of approximately ±4 degrees to ±20 degrees relative to the incident beam axis is collected and directed towards the first photodetector. More particularly, the ranges of scattering angles of collected scattered light are +4 degrees to +16 degrees and -4 degrees to -16 degrees relative to the incident beam axis, and even more particularly, +5 degrees to +16 degrees and -5 degrees to -16 degrees relative to the incident beam axis. Beneficially, given that the majority (approximately 95%) of the light scattered by interactions with particles in the sample is scattered over only a small range of angles relative to the incident light beam axis, the above-described arrangement maximizes the proportion of scattered light that can be collected by the first photodetector while minimizing the amount of unscattered light that is collected.

[0011] In some embodiments, the light collection arrangement comprises: (i) a concave elliptical reflector configured to collect only light within an angular range of approximately ±4 degrees to ±20 degrees relative to the incident beam axis and reflect it toward the first photodetector to be received by the first photodetector, or (ii) a concave elliptical reflector configured to collect forward scattered light within this angular range of approximately ±4 degrees to ±20 degrees relative to the incident beam axis and reflect it toward a collector configured to receive the light reflected by the concave elliptical reflector and focus the received light onto the first photodetector. Such an arrangement advantageously allows light within a desired range of scattering angles to be collected using only one primary component (or two cooperating components), minimizing the number of components that need to be included in the light collection arrangement and therefore need to be precisely positioned and aligned with each other. Furthermore, the use of a single reflector (formed with an appropriate shape and size) is beneficial as it reduces the space required to house the light collection arrangement, which in turn allows for a reduction in the overall size of the device itself. It should also be noted that the use of a light collection element or concentrator further increases the amount and proportion of scattered light that can be collected by the photodetector, potentially improving the sensitivity of the overall device for detecting smaller changes in scatter signal intensity.

[0012] In some embodiments, the light collection configuration includes a concave elliptical reflector configured to reflect the forward scattered light from the sample to the first photodetector or collector, and the concave elliptical reflector includes an aperture aligned with the incident beam axis and configured to allow unscattered light from the detection chamber to pass through the concave elliptical reflector. Beneficially, this configuration helps prevent unscattered light from being inadvertently collected along with the scattered light and ensure a representative measurement of actual scattering (and thus a more accurate and representative measurement of the amount of the particles present in the sample). This configuration, particularly in conjunction with the range of scattering angles described above, allows for a balance between capturing as much scattered light as possible and minimizing the amount of unscattered light captured, while maintaining an appropriate width of the source beam to sufficiently illuminate the sample and generate a significant amount of scattering. Furthermore, the ability to maintain consistent alignment of the source beam and the aperture is advantageous for optimal collection. The unscattered light can be directed toward a beam dump or exit port.

[0013] In some embodiments, the optical instrument further comprises a second photodetector configured to receive unscattered light, optionally positioned on the opposite side of the collection arrangement from the sample and aligned with the incident beam axis to receive the unscattered light. Beneficially, the second photodetector allows the unscattered light ("baseline level") to be collected and processed, which in turn allows the characteristics of this light to be measured. These characteristics can be used during processing of the scattered light collected by the first photodetector to implement noise reduction techniques when the noise obtained in the scattered and unscattered light (e.g., noise resulting from vibrations from the operation of a motor in the device) is common or correlated. Additionally or alternatively, analysis can be performed to assess light source stability and to identify fluctuations in the intensity of the incident light that may affect the scattered light signal.

[0014] In some embodiments, the collection configuration includes first and second collection lenses and a mirror, where the first collection lens is configured to direct the scattered light toward the second collection lens and to focus unscattered light traveling along the incident beam axis onto the mirror, and the second collection lens is configured to receive the scattered light from the first collection lens and focus the scattered light onto the first photodetector. The mirror can be positioned along the incident beam axis between the first and second collection lenses and can be configured to reflect the unscattered light away from the first photodetector. This configuration allows for separation of the scattered and unscattered light for processing and analysis and provides an alternative configuration that may be beneficial to the collection configurations described above that include an elliptical reflector. For example, a two-collection lens configuration uses more components, but these components may be simpler to manufacture or source (e.g., may be easier to obtain as COTS or commercial off-the-shelf parts).

[0015] In some embodiments, the mirror is configured to reflect the unscattered light towards a second photodetector, which is configured to receive the unscattered light from the mirror. As described in relation to the configuration comprising an elliptical reflector, the ability to collect and process the unscattered light provides advantages in relation to processing the corresponding scattered light signal, particularly with regard to characterizing and reducing noise.

[0016] Suitably, the device may further comprise a sample vessel carousel disposed within the sample vessel port for engaging a sample vessel and configured to align a detection chamber containing at least a portion of the biological sample in the sample vessel with the incident beam axis of the light source of the optical instrument. Beneficially, the device may be configured to engage individual sample vessels containing the sample to be illuminated by utilizing the sample vessel carousel to provide an interface and engagement function between the device and the sample vessel. This increases the ease with which one or more samples can be aligned with the optical instrument for measurement purposes.

[0017] In some embodiments, the apparatus further comprises a motor operably coupled to the sample vessel carousel and configured to rotate the carousel to periodically bring detection chambers containing at least a portion of the biological sample into and out of alignment with the incident beam axis of the light source. Automating the alignment of particular sample portions with the incident light beam simplifies the measurement process and improves the efficiency with which multiple distinct measurements of scattered light intensity can be obtained, and the reproducibility of such measurements.

[0018] Suitably, for example, the sample vessel carousel may be configured to engage sample vessels comprising multiple detection chambers, and the sample vessel carousel may be configured to rotate to sequentially move each of the multiple detection chambers of the sample vessel into and out of alignment with the incident beam axis of the light source. Beneficially, the above-described configuration provides related improvements in parallelization of sample processing and analysis procedures, i.e., using the rotatable sample vessel carousel with sample vessels comprising multiple detection chambers means that several individual sample portions can be illuminated to obtain scattered light intensities during the course of one measurement cycle / stroke. This increases the number of samples that can be analyzed over a given period of time, which is particularly advantageous when used in terms of determining the susceptibility of bacteria in the samples to one or more different drugs (and / or drug concentrations). This means that determining the appropriate drug for treatment of a particular patient / subject can be done quickly and efficiently, which is particularly useful when implemented for point-of-care devices.

[0019] In some embodiments, the sample vessel carousel includes one or more openings configured to, in use, align with the one or more detection chambers of a sample vessel when the sample vessel is properly engaged with the sample vessel carousel. The sample vessel carousel as a whole provides support and movement for the sample vessel, and the openings provided in the carousel can beneficially ensure that only appropriate / selected portions of the sample vessel (e.g., portions corresponding to the detection chambers) are disposed / placed in alignment with the incident light beam and illuminated as required.

[0020] In some embodiments, the sample vessel carousel includes one or more detectable calibration features for determining the position and / or orientation of the sample vessel carousel relative to the incident beam axis of the light source. The above-described configuration advantageously enables determination to be made as to when a given detection chamber is or will be aligned with the incident light beam, thereby ensuring that the appropriate portion or “window” of the measured signal intensity corresponding to the signal obtained from that particular detection chamber can be extracted for processing and analysis. This advantageously reduces the impact caused by any drift or inconsistency in motor rotation speed (which may occur over the course of the measurement cycle).

[0021] Suitably, the apparatus may further comprise a calibration feature reader in communication with a processor of the apparatus for determining, in use, the time interval between detection of a calibration feature by the calibration feature reader and an associated detection chamber being aligned with the incident beam axis of the light source. The calibration reader may be configured to detect the presence of a calibration feature (e.g. passing through the calibration reader itself) and to associate the detection of the calibration feature with the position of an associated detection chamber of the sample vessel.

[0022] In some embodiments, the optical instrument's processor (i) interacts with the first photodetector to measure the intensity of the scattered light received by the first photodetector during a predetermined time window corresponding to the period during which the detection chamber of the sample vessel is aligned with the incident beam axis of the light source, and (ii) adjusts the length of the predetermined interval based on detection of the or each calibration feature. Beneficially, this provides an alternative or additional mechanism for ensuring good correlation between the presence of a detection chamber in the path of the incident beam and the extraction or processing of an appropriate portion of the resulting signal for analysis.

[0023] In some embodiments, the processor of the optical instrument is programmed to periodically repeat measuring the intensity of the scattered light received by the first photodetector and determining a corresponding representative amount or concentration of bacteria present in the sample as a function of time over a period of about 20 minutes to about 2 hours, about 20 minutes to 1.5 hours, about 20 minutes to about 1 hour, or about 30 minutes to about 1 hour. The device enables the intensity of the scattered light to be monitored and analyzed over an extended period of time, such that changes in the measured intensity over that period can be detected and analyzed. For example, such changes can be used to measure changes in the number of particles in the sample, which can indicate associated changes in bacterial growth within the sample and indicate increased susceptibility (or lack of susceptibility) of the bacteria to a particular drug being tested.

[0024] In some embodiments, the device may include a temperature control system for controlling the temperature of the air within the device. Suitably, the device may further include at least one heating element and, optionally, at least one airflow regulator configured to, in use, direct heated air into contact with a sample container received within the sample container port of the optical instrument to maintain a desired temperature of the biological sample within the detection chamber. For example, to maintain a temperature of approximately 36°C to 37°C, which is a favorable temperature for bacterial growth within the sample being analyzed, maintaining such a temperature throughout the course of the measurement cycle optimizes conditions for bacterial growth during the measurement cycle.

[0025] In some embodiments comprising a pair of heating elements, each heating element is operably coupled to a fan that, in use, pushes heated air toward the sample vessel port to heat the sample in the detection chamber of a sample vessel received in the port of the device. Such a configuration can be particularly beneficial or useful for ensuring that a uniform flow of heated air passes across the sample vessel in situ within the device so as to maintain a desired temperature profile across the sample vessel.

[0026] In some embodiments, the light source of the optical instrument is a laser light source, for example, in the wavelength range of 620 nm to 780 nm, or equivalent to visible red light, when used with samples containing patient or subject urine. However, other wavelengths of light may be used, particularly when the sample corresponds to other bodily fluids such as blood. It should also be noted that the use of a laser light source (such as a laser diode) allows the frequency and amplitude of the emitted light to be relatively easily controlled and modulated as desired, i.e., the phase of the modulating signal can also be controlled.

[0027] In some embodiments, the predetermined interval corresponds to about 0.6 seconds at a rotational speed of 100 rpm. This corresponds to a suitable measurement frequency at a suitable motor speed, although it will be appreciated that the measurement frequency and / or motor speed can be varied as needed (e.g., a faster rotational speed of about 200 rpm could be utilized, which would apply a greater force to the fluid sample of interest); further, processing of the resulting signal can involve averaging of a number of individual measurements, which can be beneficial in terms of noise reduction.

[0028] In some embodiments, the processor of the optical instrument is configured to identify multiple periodically occurring peak features in the measured light intensity and to perform the measuring and determining steps only between adjacent peak features. This configuration advantageously ensures that a desired portion of the signal corresponding to the scattered light generated by interaction with the sample in the detection chamber is extracted from the resulting signal. It also minimizes the noise level in the extracted signal, for example, by avoiding inclusion in the extracted signal of light scattered by other parts of the device (e.g., by portions of the sample container or sample container carousel that do not contain any sample). This improves the signal to noise ratio of the signal being processed.

[0029] According to another aspect of the present disclosure, there is provided a system for monitoring bacterial growth in medicated liquid biological samples, the system comprising: an apparatus as defined hereinabove; and a sample container comprising a plurality of detection chambers, each detection chamber configured to receive a medicated liquid biological sample, wherein the system further comprises a sample positioning mechanism configured to align each of the plurality of detection chambers in turn with the incident beam axis such that the light source illuminates the medicated liquid biological sample contained in the illuminated detection chamber. As described above in connection with the apparatus, the ability to simultaneously process a large number of different samples during the course of a single measurement cycle has benefits with respect to parallelization of sample processing, with corresponding increases in speed and efficiency and associated reductions in costs, which can yield useful results.

[0030] Suitably, the sample positioning mechanism comprises a rotating or carousel mechanism configured to rotate the sample vessel so as to sequentially align each of the plurality of detection chambers with the incident beam axis.

[0031] In some embodiments, the system may further include a support structure configured to support the optical instrument. Providing such a support structure advantageously allows optical components to be decoupled or separated from the rest of the system components, which reduces the effects of vibrations that may be caused by operation of the sample positioning mechanism / motor on the optical components and their alignment with each other during measurement, for example. The support structure may include an opening configured to receive a portion of the sample vessel containing at least one of the detection chambers, such that when the portion of the sample vessel is positioned within the opening, at least one of the detection chambers is positionable along the incident beam axis between the light source and the light collector. This configuration advantageously ensures good / proper alignment of the sample vessel (and each detection chamber therein) with the incident light beam. Furthermore, the provision of a suitably configured opening in the support structure is beneficial in terms of guiding a user to correctly interface the sample vessel with the sample port when inserting the sample vessel into the device.

[0032] Suitably, the system may further comprise a temperature control system configured to maintain the temperature of the liquid biological sample at a temperature between 35° and 37.5°. In some embodiments, the temperature control system comprises a heating arrangement including a heating element configured to generate heat and an air circulation system configured to evenly distribute the generated heat across the plurality of detection chambers of the sample container. In some embodiments, the circulation system comprises at least one recirculation duct and an associated fan configured to induce airflow across the heating element. As described above in connection with the device, this arrangement maintains a desired and appropriate temperature within the device and around the sample container suitable for promoting bacterial growth within the sample. This increases the concentration of bacteria in the sample, thereby increasing the corresponding scattered light intensity obtainable from a given sample volume.

[0033] According to another aspect of the present disclosure, there is provided a method for determining susceptibility of bacteria in a sample to a drug, the method comprising: placing a liquid biological sample administered with a drug in a detection chamber of a sample container; illuminating the sample in the detection chamber with light emitted by a light source along an incident beam axis passing through the detection chamber; collecting, by a light collector, light scattered by interaction with bacteria in the sample, the light being scattered in a forward direction within a scattering angle range of ±4 degrees to ±20 degrees relative to the incident beam axis; and subjecting the collected scattered light to a first optical detector by the light collector. the first photodetector focusing the scattered light onto the first photodetector, measuring, by a processor, the intensity of the scattered light collected by the first photodetector and a corresponding extent of bacterial growth in the sample, repeating, by the processor, the measuring step at a series of predetermined intervals, determining, by the processor, a change in the extent of bacterial growth in the sample as a function of time, and determining, by the processor, the susceptibility of the bacteria in the sample to the drug used to administer to the sample based on the determined change in the extent of bacterial growth in the sample as a function of time. In some embodiments of this and any other aspect of the present disclosure, the scattered light is detected within a scattering angle range of ±5 degrees to ±20 degrees relative to the incident beam axis.

[0034] It will be appreciated that the various features and attendant benefits / advantages discussed above in relation to the apparatus and / or system are equally applicable in relation to the method described above.

[0035] For example, in some embodiments, the sample container comprises a plurality of detection chambers, at least two of which contain samples administered with different drugs, and the method includes sequentially positioning each of the plurality of detection chambers containing the drug-administered samples in the light emitted along an incident beam axis, performing each subsequent step of the method for each of the plurality of detection chambers, and determining the relative susceptibility of the bacteria in the sample to each drug used to administer the sample to identify the most effective drug for use in a therapeutic treatment plan.

[0036] In some embodiments, the sample container comprises a plurality of detection chambers, at least two of which contain samples administered with the same drug at different drug concentrations, and the method includes sequentially positioning each of the plurality of detection chambers containing the drug-administered samples in the light emitted along an incident beam axis, performing each subsequent step of the method for each of the plurality of detection chambers, and determining the relative susceptibility of the bacteria in the sample to each concentration of drug used to administer the sample to identify the most effective drug concentration for use in a therapeutic treatment plan.

[0037] Suitably, the method may further comprise collecting by a second photodetector unscattered light passing through the or each detection chamber parallel to the incident beam axis, and comparing, for the same detection chamber, the intensity of the unscattered light collected by the second photodetector with the intensity of the scattered light collected by the first photodetector.

[0038] Within the scope of this application, it is expressly intended that the various aspects, embodiments, examples, and alternatives described in the preceding paragraphs, in the claims, and / or in the following description and drawings, and in their specific individual features, may be employed alone or in any combination. That is, all embodiments and / or features of any embodiment may be combined in any manner and / or combination so long as those features are compatible. Applicant reserves the right to modify any originally filed claim or to file any new claim accordingly, including the right to amend any originally filed claim to depend on and / or incorporate any feature of any other claim, even if not originally claimed in the matter. [Brief explanation of the drawings]

[0039] These and other aspects of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which: [Figure 1A] 1 shows a front perspective view of an apparatus for determining the susceptibility of bacteria in a clinical sample to various drugs, according to an embodiment of the present disclosure. [Figure 1B] 1 shows a rear perspective view of an apparatus for determining susceptibility of bacteria in a clinical sample to various drugs, according to an embodiment of the present disclosure. [Figure 2] 2 shows a vertical cross section of the device of FIG. [Figure 3A] FIG. 2 is a perspective view of a portion of the device of FIG. [Figure 3B] FIG. 2 is a perspective view of a portion of the device of FIG. [Figure 3C] 3C illustrates the internal airflow and temperature gradients of the portion of the device shown in FIGS. 3A and 3B. [Figure 4] 2 is a schematic diagram of an optical configuration used in the apparatus of FIG. 1, according to an embodiment of the present disclosure. [Figure 5] 2 is a schematic diagram of an alternative optical configuration that can be used in the apparatus of FIG. 1, according to another embodiment of the present disclosure. [Figure 6]2 is a schematic diagram of an alternative optical configuration that can be used in the apparatus of FIG. 1, according to another embodiment of the present disclosure. [Figure 7] FIG. 2 is a flow diagram illustrating the various steps of a method for determining drug susceptibility of bacteria in a clinical sample using the device of FIG. 1. [Figure 8] 2 shows different plots of detector intensity output as a function of time for the device of FIG. 1 showing the effect of different drugs on bacteria in clinical samples. [Figure 9A] 2 is a vertical cross-sectional view of a sample container that can be used in the device of FIG. 1 to analyze a clinical sample. [Figure 9B] 9A is a vertical cross-sectional view of a sample container that can be used in the device of FIG. 1 to analyze clinical samples, and FIG. 9C shows an exploded view of another sample container that can be used in the device of FIG. 1. [Figure 9C] 2 shows an exploded view of another sample container that can be used in the device of FIG. 1. [Figure 10] FIG. 10 is a plan view of the sample container of FIG. 9. [Figure 10A] 12 shows different parts of the fluid structure of the vessel of FIG. 11; [Figure 10B] 12 shows different parts of the fluid structure of the vessel of FIG. 11; [Figure 10C] 12 shows different parts of the fluid structure of the vessel of FIG. 11; [Figure 10D] 12 shows different parts of the fluid structure of the vessel of FIG. 11; [Figure 10E] 12 shows different parts of the fluid structure of the vessel of FIG. 11; [Figure 11] 11 shows a plot of the detected intensity measured as a function of time when the sample vessel of FIG. 10 is used in the apparatus of FIG. [Figure 12A] 10 is a bottom perspective view of a sample carousel that can be used in the apparatus of FIG. 1 interfacing with the sample vessel of FIG. 9. FIG. [Figure 12B] 12B is a perspective view of the control used in the sample carousel of FIG. 12A. [Figure 13]2 shows different plots of detector intensity output as a function of time for the apparatus of FIG. 1 illustrating the signal to noise ratio obtainable with the apparatus of FIG. 1; [Figure 14] 2 is a plan view of an alternative configuration of a sample container that may be used in the device of FIG. 1 for analyzing clinical samples.

[0040] In the drawings, like features are designated by like reference numerals. DETAILED DESCRIPTION OF THE INVENTION

[0041] Specific examples and embodiments of the present disclosure will now be described, and many of the features will be discussed in detail to provide a thorough understanding of the concepts defined in the claims. However, it will be apparent to those skilled in the art that the present disclosure can be practiced without all of the specific details, and in some instances, well-known methods, techniques, and structures have not been described in detail so as not to unnecessarily obscure the present disclosure.

[0042] FIG. 1 shows front ( FIG. 1A ) and rear ( FIG. 1B ) perspective views, respectively, of an apparatus 1 that can be used in accordance with an embodiment of the present disclosure to provide a portable, self-contained, integrated module that can be used for clinical testing at the point of care. In such cases, a clinical sample (e.g., urine, blood, etc.) from a patient or subject can be tested using the apparatus to determine the susceptibility of bacteria in the sample to different types and concentrations of drugs. As described below, the apparatus 1 enables specific, effective drugs and treatment regimens to be identified and implemented quickly, i.e., within an hour or so, thereby providing the patient with an effective treatment regimen for an infection much more quickly than is possible with conventional detection and diagnostic devices.

[0043] 1 and 2, the device detects and measures the amount or intensity of light scattered by particles, specifically bacteria, in a clinical sample as a function of time, which thereby enables a corresponding determination of a representative amount or concentration of bacteria in the sample over time. The device 1 comprises an optical instrument or arrangement 2 and a sample positioning mechanism 4. These two components are configured to interact with a removable sample container 6 containing the clinical sample during analysis, to enable the above-mentioned determination of the representative amount or concentration of bacteria to be made.

[0044] Specifically, the sample positioning mechanism 4 is configured to engage and support a sample container 6 such that at least a portion of the sample container 6 is optically coupled or connected to components of the optical instrument 2. More specifically, the sample positioning mechanism 4 includes a sample carousel or sample carrier 8 and an operably coupled motor 10, e.g., a brushless DC (BLDC) motor or other similar drive mechanism, that controls movement of the sample carousel 8 (and thereby the engaged sample container 6). In use, the optical instrument 2 is configured to illuminate a portion of the clinical sample within the sample container 6 when the sample container 6 and the optical instrument 2 are optically coupled. The optical instrument 2 is also configured to detect and measure light scattered by bacterial particles in the illuminated clinical sample portion. The detected scattered light intensity can then be analyzed to ascertain a characteristic of the bacteria in the sample, specifically, the relative amount or concentration of bacteria in the sample as a function of time.

[0045] The device 1 includes an outer casing or housing 12 that houses the other components of the system 2. In the illustrated embodiment, the housing 12 includes a base 12a onto which the other device components are mounted: a front body portion 12b and a rear body portion 12c that form the walls of the housing 12; and a movable / removable lid 12d. In the illustrated embodiment, the lid 12d is pivotally attached to the rear body portion 12c, although other attachment mechanisms may of course be used. The lid 12d, together with the body portions 12b, 12c, and the base 12a, form an enclosure that houses the various device components when the device 1 is in use. However, it will be appreciated that various portions of the housing 12 may alternatively include more or fewer members than those described herein. The device 1 further comprises a closure / locking mechanism 13 that is used to maintain the lid 12d in a closed and locked position, for example, after the sample container 6 has already been inserted into a desired position within the device 1 and engaged with the sample carousel 8. The closure mechanism 13 comprises an actuator 13a located within the device housing 12 (shown in more detail in FIG. 2) that can be programmably activated when the lid 12d is to be opened.

[0046] The device 1 further includes a temperature control module or arrangement 14 (highlighted in FIG. 3A ) configured to maintain the temperature within the housing 12, and specifically within the area surrounding the sample container 6, within a predetermined temperature range (e.g., approximately 36°-38°C, and more specifically, approximately 36°-37°C). This temperature range is particularly favorable for promoting the growth of the bacteria in the clinical sample and maintaining them in optimal growth conditions. The illustrated device also includes a user interface 15, such as an interactive touchscreen display, through which a user of the device 1 can interact with the device 1 and program various aspects of the device 1, i.e., to view specific results and / or monitor the progress of the analytical process. For example, details of the patient or subject can be entered by the user, measurement parameters can be displayed and modified using the interface, software updates for the device 1 can be downloaded via the user's interaction with the user interface 15, and measurement progress and various intermediate and final results can be viewed by the user via the user interface 15. In addition, the user interface 15 can be used to provide instructions to the user to guide them through the various steps in the process of loading a sample into the sample container 6 and then properly engaging the sample container 6 with the sample carousel 8.

[0047] The device 1 then includes one or more processors or processing units 16 capable of providing programmable control of the various device components (e.g., the optics 2, the sample positioning mechanism 4, the lid closure mechanism 13, and / or the user interface 15). It will be appreciated that in some embodiments, the control of specific functions and components of the device may be separated / assigned to a particular one of the processing units 16. In such embodiments, the control of certain functions requiring real-time monitoring and having attendant safety implications (e.g., related to the optics 2 and temperature control arrangement 14) may be controlled by one processing unit 16, while control of certain functions related to user interface and connectivity (e.g., the user interface 15, etc.) may be controlled by a separate processing unit 16. Additionally, the device 1 may optionally be provided with side vents / openings (not shown) that can increase airflow and facilitate cooling of the processing unit 16 to prevent undesired temperature buildup within the device 1.

[0048] As mentioned above, the sample container 6 represents a separate component that can be inserted into the device 1 in order to be able to perform the required measurements and tests. Typically, the sample container 6 can be intended to be and / or effectively provide a disposable component (that can be used to test one clinical sample). For this reason, such components are also known in the art as "consumables." Further details regarding suitable and advantageous configurations of this consumable sample container 6 are provided below with reference to Figures 9-11, and additional details are also provided in the applicant's co-pending application entitled "Centrifugally motivated fluidic systems, devices and methods," the contents of which are incorporated herein by reference in their entirety to the extent applicable under domestic law.

[0049] Further details of the arrangement of the various components of the device 1 and details of the interactions between those components will now be described in relation to FIGS.

[0050] Specifically, as can be seen in those figures, the motor 10 is mounted to and supported by the base 12a of the housing 12, and the motor 10 effectively forms the support base upon which or upon which many of the remaining components of the apparatus 1 are mounted. The sample carousel 8 is substantially circular in shape and is mounted upon and connected to the motor 10 via a rotatable shaft 17 that extends along a vertically extending axis X through the center of the sample carousel 8. Rotational movement of the sample carousel 8 about the central axis X can thereby be driven by the motor 10.

[0051] The sample carousel 8 includes a plurality of openings 18 spaced radially around the sample carousel 8. According to the illustrated embodiment, the openings 18 are radially arranged around the outer portion of the sample carousel 8 (the openings are shown in more detail in FIG. 12A ). The sample containers 6 preferably include a corresponding plurality of detection chambers 20 (more clearly shown in FIGS. 9 and 10 ) spaced radially around the sample containers 6, each configured to receive a portion of the clinical sample to be analyzed. The openings 18 in the sample carousel 8 are configured such that, when the sample containers 6 are properly interfaced and / or engaged with the sample carousel 8, one position of each of the plurality of openings 18 aligns with and corresponds to one position of the plurality of detection chambers 20 provided in the sample containers 6. Thus, the detection chambers 20 can be located at any suitable location on the sample containers 6, for example, in the outer region of the carousel. As those skilled in the art will appreciate, the alignment of each opening 18 with a corresponding detection chamber 20 must be appropriate to allow light from a light source (as described below) to pass through one opening 18 and enter a respective detection chamber 20. This interface between the sample containers 6 and the sample carousel 8 is described in more detail with reference to Figure 12A.

[0052] The optical instrument 2 includes a light source 22 and collimating optics (not shown), a light collector or arrangement 24, and at least one photodetector 26. The light source 22 emits light along an incident beam axis "Y" to illuminate the sample portion present in the detection chamber 20 of the sample container 6. The light collector 24 collects light scattered in a forward direction by bacterial particles in the sample. Beneficially, the light collector 24 collects light scattered at angles of about ±24 degrees, about ±20 degrees, or about ±16 degrees from the incident beam axis Y, and more specifically, light scattered on either side of the incident beam axis Y (e.g., within a ring of a particular radius around the light beam) between +3 degrees to +24 degrees and -3 degrees to -24 degrees, +4 degrees to +20 degrees and -4 degrees to -20 degrees, and +5 degrees to +16 degrees, -5 degrees to -16 degrees. More specifically, the collected light may be scattered between +4 degrees and +16 degrees and between −4 degrees and −16 degrees on either side of the incident beam axis Y. It will be appreciated that slight differences in the curvature of the collecting element 24 mean that scattering will be collected over slightly different angular ranges on either side of the incident beam axis Y (e.g., approximately 3 degrees to 16 degrees on one side and 4 degrees to 16 degrees on the other side). Of course, those skilled in the art will appreciate that light scattered over smaller angles (i.e., less than ±3 degrees or 4 degrees on either side of the incident beam axis) can also be collected, which would increase the proportion of unscattered incident light collected by the collecting element 24. The width of the incident light beam could be reduced so that light scattered at smaller angles could be collected without including too much of the unscattered light, but this would also result in less illumination of the sample, which would reduce the amount of scattered light produced. Thus, there is a balance to be maintained in this regard, as will be described in more detail below. The collected scattered light is directed by the light collector 24 to the light detector 26, where the intensity of the collected scattered light is analyzed to ascertain, for example, the relative amount or concentration of bacteria in the sample in the detection chamber as a function of the amount of scattered light detected at a given time.The various components of the optical instrument 2 are mounted to a support plate or structure 28 to form an optical "tower" that, in the illustrated embodiment, extends substantially vertically upward from and is supported by the motor 10 or its housing 10a. However, it will be appreciated that the mounting of the optical "tower" 28 may be separate or detached from the motor 10 and its housing 10a to isolate the optical instrument 2 from any vibrations that may be caused by the motor 10. Thus, in either case, the optical tower 28 structure is also substantially perpendicular to the plane on which the sample carousel 8 and sample containers 6 rest, in use. Thus, the incident beam axis "Y" of the light emitted from the light source 22 is parallel to the axis of rotation "X" of the sample carousel 8, but is laterally offset a distance "d" from the axis of rotation.

[0053] The lateral offset "d" between the rotation axis X and the incident beam axis Y corresponds substantially to the radial distance (of the center) of the detection chamber 20 from the center of the sample container 6, and also corresponds to the radial distance between the center of the sample carousel 8 and the area of ​​the opening 18 provided in the platform. The support structure 28 for the optical instrument 2 has a gap or notch 30 provided therein and disposed between the light source 22 and the light collection arrangement 24 (somewhere in the vertical plane) and in the plane of the sample carousel 8, this notch 30 being sized and arranged to receive a radially outer portion of the sample carousel 8 therein. This contained portion of the sample carousel 8 (and thus the corresponding portion of the sample vessel 6 when the sample vessel is engaged with the sample carousel 8) can therefore enter and pass through the support structure 28 and optical tower, thereby intersecting the incident beam axis Y of the light emitted from the light source 22. In practice, the sample carousel 8, support structure 28, optical instrument 2 and sample vessel 6 are designed and adapted so that, in use, the light emitted by the light source 22 can pass through one of the openings 18 of the sample carousel 8 and then enter the corresponding detection chamber 20, thereby illuminating and analyzing the sample portion contained within that detection chamber 20.

[0054] As a result, when the sample vessel 6 is engaged with the sample carousel 8, each of the detection chambers 20 of the sample vessel 6 can be sequentially positioned in the incident beam axis "Y" by rotation of the sample vessel 6 by the motor 10 through the beam path of the light from the light source 22. Thus, scattered light from the bacterial particles in the portion of the sample contained in each detection chamber 20 can be sequentially collected and measured by the optical instrument 2. In some embodiments, by "measuring" it is meant to quantitatively assess the amount / intensity of the light scattered by bacteria in the sample, whereas in other embodiments a qualitative assessment of the relative amount of scattering caused by sample in different sample chambers can be performed.

[0055] In the illustrated embodiment, the optical instrument support structure 28 comprises an upper (protruding) cover portion 32 that covers (and may provide support functions for) some of the components of the optical instrument 2, such as the light collection arrangement 24 and the light detector 26. The upper cover 32 may also perform the additional useful function of preventing unscattered light traveling along the substantially vertical incident beam axis "Y" from exiting the device 1 or accidentally reaching the user of the device 1 (for example, if the lid 12d of the housing 12 is removed while the light source 22 is emitting light). Additional details regarding various configurations of the optical instrument 2 are provided below in connection with Figures 4-7.

[0056] Considering now the temperature control module 14, as seen in FIGS. 2, 3A, 3B, and 3C, this portion of the apparatus 1 is mounted on and supported by the motor 10 and its housing 10a, and includes at least one heating element 34 and a circulation arrangement 36. Each heating element 34, e.g., a heating coil or arrangement / multiple heating coils, may be disposed within a corresponding compartment or chamber 38 disposed below the sample carousel 8. In the illustrated embodiment, a pair of heating elements 34 is provided disposed in a plane above the motor 10 below the sample carousel 8 (see FIG. 3A), with each of the pair of heating elements 34 disposed on a respective side of the optics support structure 28. As those skilled in the art will appreciate, each heating element 34, in use, heats the air in its vicinity, which rises toward the underside of the sample carousel 8 and its associated sample vessels 6. The circulation arrangement 36 then circulates the air more widely throughout the device housing 12, thereby maintaining a substantially constant flow of heated air over and around the sample containers 6, thereby maintaining the temperature of the contents of the sample containers 6 within a desired (optimal) temperature range to promote rapid bacterial growth and proliferation. In the illustrated embodiment, the circulation arrangement 36 includes a pair of recirculation ducts 40 having an inlet 40a disposed at a level above the sample containers 6 and an outlet 40b disposed at a level below the sample carousel 8. In this manner, the temperature of the air within the apparatus can be rapidly adjusted as needed. The circulation arrangement 36 also includes one or more associated fans 42 or other mechanisms for causing airflow around the circulation arrangement 36. Specifically, in the illustrated embodiment, each heating element 34 has a fan 42 coupled thereto for causing circulation of the air heated by that heating element through the circulation arrangement 36.

[0057] 3C shows in detail the air movement achieved by the temperature control module 14. Each heating element-fan pair is disposed at the base of its corresponding recirculation duct 40. The fan 42 causes a constant flow of air through / across the associated heating element 34, and this heated air is forced out the corresponding outlet 40b of the recirculation duct 40 into an antechamber or intermediate compartment 43 below the sample carousel 8. The heated air then rises upward in the apparatus, flowing across and around the sample container 6, cooling it in the process. This relatively cool air then enters the inlet 40a of the recirculation duct 40, replacing the air displaced by the fan 42, and flows back down toward the heating element-fan pair. Because the recirculation ducts 40 are disposed on either side of the optical instrument 2, the material used to form these ducts 40 is appropriately shaped and configured to prevent the heated air from causing overheating of the optical instrument components. This helps to prevent any undesired distortion or failure of those components, or to prevent erroneous measurements from being made due to excess heat.

[0058] While the device is illustrated in Figures 3A, 3B, and 3C as having a pair of heating elements, each with multiple heating coils, it will be understood that one or more heating elements may be appropriate according to preference and design. Furthermore, while multiple heating coils may be advantageous in implementing rapid heating of the air within the chamber in this embodiment of the invention, a single heating coil may also be used, or alternatively, one or more heaters in many other forms and configurations are available to those skilled in the art and may be selected according to preference. Similarly, while the device of the present invention is illustrated with a pair of fans (one for each heating element) to push warm air around the device's internal chamber, in some embodiments, fans are not necessary; for example, airflow caused by rotation of the sample containers 6 and sample carousel 8 could generate movement of heated air toward and around the sample containers 6.

[0059] Providing pairs of effective mirrored arrangements of heating elements 34 and fans 42, each with its corresponding recirculation duct 40, on either side of the sample carousel 8 has proven particularly useful in maintaining a good balance of heating within the apparatus 1. This arrangement also corrects for any asymmetry in heating that may result from continuous rotation of the sample container 6 in a particular direction. Furthermore, heating the sample container 6 in this "bottom-up" manner (i.e., the air is heated and rises quickly through the sample container 6) allows for faster and easier heating of the sample portions contained within their respective detection chambers, without wasting additional heat (and heating time) in heating up the material in the sample container 6 itself. Thus, if the sample container 6 contains multiple samples in different detection chambers 20 surrounding the sample container 6, heating of the sample in each detection chamber 20 is beneficially consistent. In some cases, maintaining a desired consistent temperature of the sample in the sample container 6 can be performed with the aid of a temperature measurement device (such as an infrared or IR thermometer) disposed within the apparatus 1, for example, on or near the sample container 6.

[0060] FIG. 4 shows details of an exemplary configuration of the optical components of the optical instrument 2. In this configuration, the light source 22 corresponds to a laser module having a laser diode used to generate light at a specific wavelength (e.g., in the range of 620 nm to 780 nm, and more specifically, visible red light at a wavelength of approximately 635 nm) to illuminate the sample portion contained within the detection chamber 20. While the above wavelengths are envisioned for use in connection with the analysis of urine samples, it should be noted that the wavelength of light used may vary depending on the nature of the sample to be analyzed. For example, near-infrared wavelengths (approximately 650 nm to approximately 1350 nm) could be used in connection with blood samples. The laser diode is connected to a signal generator (not shown) adapted to control the modulation frequency and amplitude of the laser output. The photodetector 26 corresponds to a photodiode connected to a lock-in amplifier (also not shown), which is in turn connected to the signal generator for the laser diode. This allows the photodiode to isolate and reject a particular received signal having a frequency corresponding to the modulation frequency generated by the signal generator for the laser diode, which allows noise signals at other frequencies (e.g., background noise, electrical noise) to be rejected, thereby improving the signal-to-noise ratio obtainable with the optical instrument 2. These components may be controlled via one or more of the system's processors 16, which may take the form of one or more printed circuit boards (PCBs) or other types of microcontrollers.

[0061] The light collector 24 in this example comprises a reflector or reflective surface that, in the illustrated embodiment, is mounted to the support structure 28 so as to extend across the incident beam path. Specifically, the light collector 24 in Figure 4 corresponds to a curved, concave, elliptical mirror 44 having an off-center hole, aperture, or opening 46 formed therein. The mirror 44 is mounted to the support structure 28 so that the hole 46 is aligned with the incident beam axis "Y", thereby allowing unscattered light exiting the detection chamber 20 and traveling along the beam axis "Y" to pass directly through the mirror 44 substantially undeviated, thereby preventing this unscattered light from reaching the photodetector 26. Furthermore, the mirror 44 is angled and sized so that the light scattered in the forward direction by the particles in the sample, and specifically the light scattered within an angular range of about +4 degrees to +16 degrees and about −4 degrees to −16 degrees from the incident beam axis Y, is reflected by the mirror 44 toward the photodetector 26. In some other embodiments, the light reflected by the mirror 44 toward the photodetector 26 can be within an angular range of about +5 degrees to +16 degrees and about −5 degrees to −16 degrees from the incident beam axis Y.

[0062] Those skilled in the art will appreciate that when considering the sensitivity of scattered light detection, there is an interaction between the size of the light collector (mirror) aperture 46, the width of the light beam from the light source 22, and the width (diameter) of each detection chamber 20 in the sample container 6 through which the light beam passes. A trade-off between these values ​​is necessary to optimize the sensitivity of scattered light detection. Increasing the width of the light beam from the light source 22 increases the amount of (bacterial) particles in the sample illuminated by the light beam, which in turn increases the amount of scattered light generated in any given scattering event that can be detected. However, when performing measurements of scattered light emerging from a detection chamber 20, extending the time that the full width of the light beam illuminates the sample in the detection chamber 20 results in a longer, "cleaner" measurement path / zone of the light beam through the sample (away from the walls of the detection chamber 20, which can cause internal scattering, which would reduce the accuracy with which scattered light from the sample is detected). Thus, increasing the light beam width increases the detection sensitivity, but to balance these two factors, the light beam width must nevertheless remain smaller than the width / diameter of the detection chamber 20. It will be further appreciated that configuring the system so that the diameter of the aperture 46 of the collector (mirror) is as close as possible to the width of the light beam will allow as much scattered light as possible to be collected and directed toward the photodetector 26 while minimizing the amount of unscattered light that is collected. However, if the width of the light beam closely matches the diameter of the aperture 46, slight deviations in the path traveled by the light beam during measurement (due to vibrations or machining tolerances of the components in question) can adversely affect the alignment of the light beam with the aperture 46, which will therefore have a corresponding adverse effect on the detection sensitivity.

[0063] In certain embodiments, the diameter of the detection chamber 20 is approximately 4 mm, and it is envisioned that a light beam width of approximately 1 mm to 3 mm (more specifically, 1.5 mm to 2.4 mm) would provide a good balance between the number of illuminated bacterial particles and the length of the “clean” measurement path within the detection chamber 20. In such an embodiment, if the width of the aperture 46 is selected to be approximately 3 mm, a light beam width of approximately 1.5 mm, for example, would be suitable for use, since sufficient room is left between the aperture width and the light beam width to account for machining tolerances and / or system vibrations. However, if the aperture 46 is larger (e.g., a diameter of 4 mm to match the diameter of the detection chamber 20), the light beam width used may increase accordingly (e.g., to approximately 2 mm to 2.4 mm).

[0064] In the configuration of the illustrated embodiment, a concave elliptical mirror 44 reflects the forward scattered light at a predetermined angle away from the incident beam axis Y (and substantially 90 degrees away from the incident beam axis Y) so that it is focused onto the photodetector 26. One or more of the system processors 16 are coupled to the photodetectors 26 and process the detection signals generated by the photodetectors 26 to calculate the intensity of the detected scattered light. A graph or plot of detector output (corresponding to the measured scattered light intensity as a function of time) can be generated; an example of such a graph is shown in FIG. 8. This graph and / or the data used to generate it can be displayed to the user via the user interface 15, for example, at regular intervals as a substantially real-time indication of progress, or as a final (summary) output once the analytical process for a given sample is complete.

[0065] 4, the system in this embodiment also includes a second photodetector 48 aligned with the incident beam axis "Y," but disposed on the opposite side of the collector 24 from the sample, and configured to detect and measure the unscattered light that passes through the hole 46 in the mirror 44. This second photodetector 48 also corresponds to a photodiode that can be configured in substantially the same way as the first (primary) photodetector 28; i.e., the second photodetector 48 is connected to the signal generator of the light source 22 via a lock-in amplifier to ensure that the second photodetector 48 (and / or one of the processors 16 associated with it) can also remove the desired laser signal frequency (and phase) from any noise signals different in frequency from the laser. The provision of this additional second photodetector 48 allows a baseline measurement of the unscattered laser light to be obtained. This baseline measurement can be compared to the scattered light intensity measurement measured using the first (primary) photodetector 26, allowing, for example, anomalies in illumination to be detected, and the stability of the laser can also be evaluated and taken into account during analysis. It will be appreciated that in any of the embodiments of the present disclosure, second photodetector 48 may be omitted. In some such embodiments, a beam dump or other device may be used to collect unscattered light from the laser.

[0066] In some cases, the mirror 44 is manufactured by a customized molding process to ensure the appropriate size, shape, and reflective properties. During such a process, the reflective surface of the mirror 44 may be formed by, for example, vapor deposition coating of the mirror surface with aluminum or reinforced aluminum. In some optional cases, the mirror's reflectivity (at about 650 nm) must be greater than 90% (e.g., at least 95% or 98%), and the mirror's surface roughness must be less than 100 Å (e.g., less than 80 Å, less than 60 Å, or even 40 Å or less). While the optical configuration shown in FIG. 4 is particularly useful in reducing the number of components required to implement the present disclosure, other optical configurations are possible. For example, the customized concave elliptical mirror 44 of FIG. 4 may be replaced with a pair of reflective elements, such as a first mirror that deflects forward-scattered light onto a focusing lens or a second concave mirror that focuses the reflected light from the first mirror onto the photodetector 26. Additionally or alternatively, one or more additional light collection components may be incorporated into the optical configuration 2 in association with or in conjunction with the photodetector 26. For example, one or more light collection components (e.g., concentrators) may be configured to form a "collection cone" around the photodetector 26 to maximize the amount of scattered light collected by the photodetector 26.

[0067] An alternative optical configuration 2′ is illustrated in FIG. 5 , in which an off-the-shelf concave mirror 44′ can be used rather than the customized, specifically shaped mirror 44′ (although the reflectivity and surface roughness characteristics must be comparable). In this case, the curvature of the mirror 44′ need not necessarily be configured to focus all (or at least substantially most) of the forward scattered light from interaction with the sample onto the photodetector 26. In such a case, an additional light-collecting component 50 (e.g., a concentrator such as a Fresnel lens) may be introduced into the optical configuration in the optical path between the mirror 44′ and the photodetector 26 to ensure that as much of the forward scattered light as possible reflected by the mirror 44′ is captured and focused onto the photodetector 26. This maximizes the total amount of scattered light obtainable using the optical configuration 2′, which in turn increases the sensitivity of the overall apparatus for detecting smaller changes in the relative amount or concentration of bacteria in the sample over time. In other embodiments, as described above, the lens 50 could be replaced with a second mirror configured to reflect light onto the photodetector 26. The additional light collection components described above in connection with the optical configuration 2 of Figure 4 may also be incorporated into the optical configuration 2' in addition to or as an alternative to the light collection components 50 described above.

[0068] FIG. 6 shows another alternative optical configuration 2″ which is intended to collect scattered and unscattered light separately, the beam paths of the two types of light being shown in the drawing. In this alternative configuration, the collecting section 24 comprises a pair of collecting lenses 52a, 52b which are separated by a distance “a” which is greater than the focal length of the first lens 52a and which are oriented so that the convex faces of the lenses face each other along the incident beam axis Y. In this configuration, any diverging beam of light incident on the first collecting lens 52a is collimated into a parallel beam of light which is also parallel to the incident beam axis Y. Such a parallel beam of light is then focused towards a point a further distance along the incident beam axis Y when it enters the second collecting lens 52b. However, any parallel beam of light which passes through the centre of the first collecting lens 52a (or within the region corresponding to light scattered at a maximum predetermined angle from 0° to, for example, 5°) will instead be focused to a point at the focal length of that lens 52a. In the illustrated configuration 2″, the light collecting unit 24 further includes a mirror 54 disposed at a position corresponding to the focal length of the first collecting lens 52a and sized and oriented to reflect only light that enters the first lens at an angle of incidence less than or equal to the maximum predetermined angle. Light that passes through the sample substantially without scattering will therefore strike the surface of the mirror and be deflected away from the second lens 52b before reaching the second collecting lens 52b. In the illustrated embodiment, the mirror 54 is angled (substantially 45 degrees) with respect to the incident beam axis Y (although other angles may be selected), so that any light beam incident on the mirror 54 is reflected by approximately 90 degrees with respect to the incident beam axis Y and directed away from the main incident beam path; therefore, this light will not reach the second collecting lens 52b.

[0069] As in the case of the optical equipment configurations 2, 2' shown in Figures 4 and 5, the laser diode light source 22 in the current configuration 2'' of Figure 6 emits light along the incident beam axis Y, which illuminates the sample in the detection chamber 20 of the sample container 6, and bacteria in the sample scatter the incident light beam in a forward direction and over a corresponding relatively small angular range. 4 and 5, two photodetectors are provided in the optical configuration 2" of FIG. 6: a first "off-axis" photodetector 26' is positioned angularly offset (by approximately 90 degrees) with respect to the incident beam axis Y, and a second "on-axis" photodetector 48' is positioned in alignment with the incident beam axis Y. However, in the optical configuration of FIG. 6, the unscattered light passing through and exiting the detection chamber 20 in a collimated beam is focused by the first collecting lens 52a onto the mirror 54 and then onto the offset off-axis photodetector 26'. The forward scattered light beam produced by the interaction of the incident light with bacteria in the sample is focused by the pair of collimating lenses 52a, 52b onto the on-axis photodetector 48'. This is in stark contrast to the configurations of Figures 4 and 5, where it is the off-axis (primary) photodetector 26 that detects the scattered light and the on-axis photodetector 48 that detects the unscattered baseline laser light.

[0070] By using one of the optical configurations 2, 2', 2" described above, the apparatus 1 can optimize / maximize the collection of scattered light useful in assessing the properties and / or quantity of the bacteria in the sample. This is because applicant has appreciated that the majority (approximately 95%) of the light scattered as a result of such bacterial interactions is scattered only over a relatively small range of angles on either side of the incident beam axis Y, for example, ±20 degrees from the incident beam axis Y (and more specifically, at angles of about 4 or 5 to 16 degrees on either side of the incident beam axis Y). Thus, instead of requiring an integrating sphere or other form of collector that utilizes multiple reflections and / or diffusion of scattered light (possibly including backscattered light) to increase the collected light intensity, a simplified light collection configuration can be used that is configured to collect the light scattered over those specified angular ranges that are most relevant to the evaluation / measurement of particles in the sample and to direct / focus the collected light onto a photodetector.

[0071] Next, a method for using the above-described device 1 will be described with reference to FIG.

[0072] Initially, in step 105, the user securely places the clinical sample in the sample container 6, after which, in step 110, the sample container 6 is inserted into the appropriate position within the device 1. This involves properly aligning the sample container 6 with the optical tower support structure 28 (e.g., aligning an indent or cut-out segment or other surface feature 58 of the sample container 6 with the support structure 28 or a corresponding / complementary structure on the device 1) and engaging the sample container 6 with the sample carousel 8, for example, via a click-in / clip-in and pull-out mechanism. In some embodiments, this process can be guided by the user interface 15 (e.g., via a series of diagrams and corresponding written / spoken instructions). In some embodiments, the sample carousel 8 itself may also be removable, if necessary, to facilitate easy cleaning. Then, in step 120, the lid 12d of the device 1 is closed and locked in place, and the user interacts with the user interface 15 to initiate a sequence of pre-programmed operations to be performed by the various components of the device 1 to perform the desired sample analysis.

[0073] Before these pre-programmed operations are performed, or indeed as part of those operations, the device 1 can be configured to identify the sample container 6 in step 115 and determine information associated with the particular sample container 6 based on data provided on the sample container 6 itself or on the sample container's packaging. In some cases, this information may be contained within or obtainable via a unique identification code provided with the sample container 6, which may include a unique identifier associated with the sample container 6 itself, a unique identifier associated with the particular batch of which the sample container 6 is a part, and an expiration date for the contents of the sample container 6. This identification code may be provided in the form of an RFID tag or barcode (e.g., a 2D barcode) that can be scanned by the device 1 prior to the insertion of the sample container 6 (e.g., via a separate scanner associated with the device 1) or after insertion of the sample container 6 (e.g., via a scanner integrated into the device 1). For example, an internal barcode scanner / reader 59 is shown (in the illustrated device of FIG. 2) attached to the interior wall of the device's housing 12. In this embodiment, the scanner 59 is mounted at a particular angle such that it is directed toward an identifying RFID tag or bar code disposed on the sample container. For example, the bar code or other means of identification can be disposed on an angled portion 58a of the sample container 6 (e.g., positioned adjacent the cutout segment 58 of the sample container 6 so that the bar code can be read by the scanner 59 once the sample container 6 is inserted into the device 1, as shown in Figures 9A and 9B).

[0074] Additional information may also be provided as part of or in addition to the identification code, for example details of the particular drug provided in each of the detection chambers 20 of a given sample container 6, so that the analysis is carried out with information of the drug being tested for. Furthermore, details regarding software updates that may need to be implemented may also be included as part of the information provided, allowing the device 1 to easily and efficiently obtain information about appropriate software updates and modifications that may be required from the sample container 6 itself.

[0075] Additionally or alternatively, the unique identification code may be provided on the packaging of the sample vessel 6 (e.g., on a box containing one or more sample vessels 6 of a particular batch), or may be provided with the packaging, for example in the form of a USB memory stick that already has associated and relevant identifying information built into it. Advantageously, providing this information using the packaging or a separate USB memory stick increases the storage space available to accommodate the data, thereby allowing more data to be provided within the identification code. In such cases, the device housing 12 may include a port for receiving and interfacing with the USB memory stick.

[0076] The device 1 may also be programmed to verify that the sample container 6 is one of an approved batch of containers that can be used with the device 1 (e.g., to identify any counterfeit or unauthorized sample containers and prevent them from being used with the device 1). In this regard, the sample container 6 may be provided with an identifying (anti-counterfeit) feature that is detectable by the device 1, which may be provided as part of or in addition to the unique identification code described above. The device 1 may be programmed to reject or refuse to process any sample container 6 that does not include such a feature.

[0077] 10 and 11, the sample container 6 comprises a central sample chamber 60 in which the clinical sample is initially held, and a plurality of detection chambers 20 which represent final destinations for the various individual sample portions where they are illuminated and analyzed. Thus, in step 125, the first series of pre-programmed operations performed by the apparatus 1 is to operate the motor 10 to rotate at a particular number of revolutions, in a particular predetermined direction, and for a particular period of time in order to redistribute portions of the clinical sample from the central sample chamber 60 to each of the plurality of detection chambers 20. This sequence involves the following sequential steps: (a) mixing the clinical sample with a growth medium 62 provided in the sample container 6 to create an environment conducive to bacterial growth; (b) distributing smaller sample portions into each of a plurality of radially extending fluidic structures 64 to remove unwanted particles (e.g., sediments, etc.) from the sample; (c) mixing the smaller sample portions with a corresponding drug (e.g., antibiotic) provided in each fluidic structure 64; and (d) retaining the final medicated sample in its corresponding detection chamber 20 for irradiation and analysis over time. Of course, in some applications, a control sample will not be exposed to antibiotics or other drugs.

[0078] Once this process is performed and the various drug-dosed sample portions have been redistributed to their respective detection chambers 20, the next series of pre-programmed operations performed by the apparatus 1 involves the analysis of the samples in each detection chamber 20. The motor 10 is programmed to drive the rotation of the sample carousel 8 and associated sample containers 6 at a constant rotational speed (e.g., 100 or 200 rpm) over an extended period of time (e.g., over the course of about 60-90 minutes) so that a given location on the sample container 6, e.g., a particular detection chamber 20, performs a full rotation approximately every 0.6 seconds. Accordingly, in use, each detection chamber 20 will pass through the incident beam axis Y at a predetermined interval (e.g., approximately every 0.6 seconds for a 100 rpm rotational speed) at a rotational speed of approximately 100 or 200 rpm. Each sample portion within its respective detection chamber 20 is thereby illuminated in turn (at predetermined time intervals), and the scattered light can be collected by the photodetector 26 and processed / analyzed at regular intervals over the course of the assay (bacterial growth / antibiotic susceptibility analysis). In some cases, given the frequency of measurements, it is contemplated that a (weighted) moving average of sample measurements can be used to process and combine the scattered light measurements obtained from each detection chamber 20. This would beneficially reduce the noise associated with each averaged sample measurement point (by the square root of the number of individual measurements combined to obtain the weighted average). For example, it is contemplated that in some cases the moving average could be applied over one hundred measurements (e.g., 60 seconds at the expected 100 rpm rotation speed). In some embodiments, the rotation speed of the sample carousel 8 (and sample containers 6) is selected according to preprogrammed / factory settings and can be determined according to the processing speed of the device 1 and / or the desired frequency of measurements. Thus, the rotation speed of the sample vessel 6 during the assay may be faster or slower than 100 rpm (e.g., 50-300 rpm). Similarly, the length of the assay may be based on pre-programmed / factory settings or, in some embodiments, may be set according to user preference.For example, the length of the assay can depend on the type of bacteria and / or the antibiotic to be tested against the bacteria, and can be about 20 minutes to 4 hours, e.g., about 20 minutes to 2 hours, or about 20 minutes to 1.5 hours. In some preferred embodiments, the length of the assay is about 20 minutes to 1 hour, or about 30 minutes to 1 hour.

[0079] As briefly mentioned earlier in this document, the intensity of the signal generated by the main "signal" photodiode 26 (in optical configurations 2 and 2') and the photodiode 48 (in optical configuration 2") as a result of the measured scattered light intensity correlates with the amount and / or concentration of (bacterial) particles in the sample being analyzed / assayed. In other words, a larger / stronger signal corresponds to a greater amount of light scattering and thus a greater scattered light intensity, which in turn indicates a higher concentration of (bacterial) particles in the sample. Therefore, a graphical display of the detection signal over time (based on the scattered light intensity) can be used to visualize the time-varying changes in the amount and / or concentration of bacteria in a sample, and thereby indicate and ultimately determine the sensitivity of the bacteria in that sample to the type and concentration of drug that has already been administered to that particular sample.

[0080] An example of such a graphical display is shown in FIG. 8, where the susceptibility of bacteria in clinical samples to five different antibiotics was tested. In this example, the sample container 6 was divided into 28 separate detection chambers 20 and associated flow paths for separating the clinical sample into the 28 detection chambers 20, so that up to 28 separate assays could be performed simultaneously. The 28 assays were divided into four regions, labeled Region 1 through Region 4 (see FIG. 8), and in each region, five antibiotic susceptibility tests were performed along with one negative control (in which the detection chamber was modified (e.g., made opaque) to prevent incident light from passing through) and one positive control (to follow uninhibited bacterial growth in the absence of any antibiotics). In this case, five different antibiotics were supplied to each of the five assay chambers in each region, so that bacterial susceptibility to each antibiotic could be tested four times per sample container 6, one test in each of the four regions. In this way, the reproducibility of the assay could also be assessed around the sample container 6. The sample container 6 was rotated at approximately 100 rpm, and measurements of the scattered light intensity collected from each detection chamber 20 were taken over the course of approximately 80 minutes.

[0081] As is evident from the graph in Figure 8, the detection analysis chambers serving as the positive controls exhibited a generally exponential increase in detected scattered light intensity (and thus a corresponding exponential increase in bacterial amount and / or concentration) over the course of the measurement period. This reflects the degree of increase in bacterial amount and / or concentration that would typically be expected (under the assay conditions) in the absence of drugs or other inhibitors and when the bacteria were allowed to grow and replicate normally in a solution containing sufficient growth medium. Meanwhile, the detection chambers serving as the negative controls exhibited minimal detected intensity over the entire measurement period, as expected. Four of the five detection chambers containing various antibiotics exhibited changes in detected intensity, indicating a decrease in bacterial amount and / or concentration (compared to the positive control) as a result of the antibiotic's action, i.e., curves with a lower or more negative slope compared to the positive control curve, but still (at least initially) having values ​​above the negative control line. Therefore, the sample administered with the various drugs that shows the greatest decrease in the measured light scattering intensity over time compared to the positive control sample (theoretically) corresponds to the sample that has already been administered with a specific type and / or concentration of antibiotic to which the bacterial strain present in the sample is most susceptible. Therefore, when treating the patient from whom the clinical sample was obtained, it is easy to determine which antibiotic and what concentration will be most effective over a relatively short period of time. However, the antibiotic administered may not always be optimal, for example, if the bacterial culture response changes over a longer period of time or if a certain antibiotic takes time to become effective.

[0082] Of course, it is possible (and indeed quite likely) that many different antibiotics may be identified to which the bacteria in the sample may be susceptible. Therefore, a variety of different approaches can be considered for determining the most appropriate antibiotic to use in treatment. For example, the ability to terminate the analysis allows the user to be presented with the susceptibility results in real time at any time after at least one antibiotic has been determined to be effective. However, for example, if the bacterial culture response changes over a longer period of time, or if an antibiotic takes longer to become effective, this may not necessarily be the most appropriate antibiotic to administer. Alternatively, another approach may be to limit the time the test is performed (e.g., 30 minutes, 45 minutes, or 1 hour) and present the results to the user after that time, meaning that multiple (or no) antibiotics and / or dosage levels may be considered for administration to the subject. Another option is to simply present the results after a certain number of antibiotics have been deemed effective. Of course, this means that the turnaround time required for the test will vary. Of course, a combination of these approaches may also be employed.

[0083] It will be appreciated that the drug or antibiotic used in each assay and the respective concentrations can be selected based on many factors, such as the geographic location where the device will be used and / or the suspected medical indication and potential bacterial infection being screened. For example, if the biological sample includes urine for assaying antibiotic sensitivity for urinary tract infection (UTI), the antibiotics used can be selected from one or more of the following group: amoxicillin, amoxicillin / clavulanic acid (2:1 combination), cephalexin, ciprofloxacin, ertapenem, fosfomycin, levofloxacin, mecillinam, nitrofurantoin, trimethoprim, trimethoprim / sulfamethoxazole (1:19 combination). However, the antibiotics selected, and their concentrations or concentration ranges, can take the form of any antibiotic (concentration) designed to produce the desired results during the screening.

[0084] As is evident from a comparison of the graphs for the different regions, an increase in the signal noise level is detected over the course of the rotation, i.e., the signal measurements obtained for region 4 (corresponding to detection chambers 20 near the end of each rotation) exhibit significantly more noise scattering than those obtained for region 1. The cause of this increase in noise, along with a method for dealing with this increased noise, will be described in more detail below with reference to Figures 11 and 12. The results of this method are shown in Figure 13, which shows that the signal-to-noise ratios across the various detection chambers 20 in the different regions of the sample container 6 exhibit fairly small variations and are in fairly good agreement with each other. This will be described in more detail below with reference to Figure 13.

[0085] Nevertheless, those skilled in the art will appreciate that the embodiments of the present disclosure described herein provide benefits with respect to parallel processing of sample analysis. Specifically, the configuration of the sample container 6 means that multiple different drugs (at a variety of different concentrations) can be tested on the same subject sample during the course of a single measurement cycle, and the results can be directly compared to each other, minimizing the equipment and time required to perform the evaluation. Such parallel analysis of multiple different drugs and concentrations also helps to eliminate environmental influences on the test results from a single subject sample.

[0086] To aid in understanding the function of the device, a schematic of the consumable sample container 6 is described in conjunction with FIGS.

[0087] As previously mentioned, the sample vessel 6 is substantially circular in vertical cross-section and includes a common (central) sample well or reservoir 60 in communication with a plurality of detection chambers 20 spaced about the radially outer periphery of the vessel 6. Each detection chamber 20 is fluidly connected to the common sample reservoir 60 via a respective fluidic structure or fluidic system 64 (comprising a plurality of flow paths 66, 68). However, the detection chambers 20 are otherwise fluidly isolated from one another. The fluidic structure 64, sample reservoir 60, and detection chambers 20 are located at the base of the sample vessel 6. The fluidic structure 64 utilizes the centrifugal / centripetal force generated by rotation of the sample vessel 6 by the motor 10 to induce flow of the sample from the sample reservoir 60, through the respective flow paths 66, 68, and ultimately toward the respective associated detection chambers 20. The radial distance of each detection chamber 20 from the central rotation axis X of the sample container 6 corresponds to "d", i.e., the distance between the rotation axis X of the sample container 6 and the incident beam axis Y, to ensure that, in use, as the sample container 6 rotates within the device 1, the light beam from the light source 22 passes through the detection chambers 20 in sequence so that individual measurements of scattering intensity can be obtained from each sample portion within the sample container 6.

[0088] As will be appreciated, because the detection chamber 20 is integrally formed within the illustrated sample vessel 6, the sample vessel 6 (or at least the portion of the sample vessel 6 that includes the detection chamber 20) is formed of a material that is optically transparent (or at least substantially transparent to light at the wavelength of the light source) to allow the light from the light source 22 to enter and exit the detection chamber 20. Specifically, in the illustrated configuration, the incident light from light source 22 passes through the base or lower surface of the sample vessel 6 in a position aligned with the illuminated detection chamber 20 before exiting the top surface of the sample vessel 6 toward the light collector 24. However, it will be appreciated that other configurations / relationships between the light source 22, detection chamber 20, and light collector 24 are possible and within the scope of the present disclosure.

[0089] The illustrated sample vessel shown in Figure 10 includes nineteen detection chambers 20 and their associated fluidic structures 64, and has "cutout" segments 58 approximately equal in size to four or five detection chambers 20 and their associated fluidic structures 64. However, it will be appreciated that a different number of detection chambers and / or cutout segments 58 formed in different sizes or shapes (or even no cutout segments, as in the case of the sample vessel used to generate the data of Figure 8) could be used without departing from the scope of the present disclosure. For practicality and efficiency in maximizing the number of fluidic structures 64, the cutouts 58 can, for example, subtend an angle of about 20° to 60°, suitably about 30° to 50°.

[0090] For ease of manufacturing, the fluidic system 64 is formed as channels, reservoirs, and recesses in the lower surface of the sample container 6. Therefore, to form a closed system, a base cover 6c having a surface area footprint corresponding to the base of the sample container 6 is attached to the bottom of the sample container 6 to close the assembly and cover the fluidic system 64 and sample reservoir 60 formed in the lower surface of the sample container 6 (see FIG. 9C). Suitably, the base cover 6c is a film. Without the base cover 6c, the fluidic system 6 would be open to the environment and would be unable to contain liquid when the fluidic device 1 is in use. The base cover 6c is optically transparent at least in the region axially below (some of) the detection chambers 20 to enable subsequent analysis of the bacteria (or other particulate matter evaluated for light scattering ability) in the respective detection chambers 20. In some embodiments, the base cover 6c may be opaque to light in certain predetermined areas, such as beneath the detection chamber 20 to provide an optical negative control during use.

[0091] The base cover 6c can be attached to the bottom surface of the sample container 6 by any one or more of several well-known suitable sealing methods, such as heat sealing, ultrasonic welding, liquid adhesive sealing, etc., or the base cover 6c can include a single-sided / double-sided adhesive film. Regardless of the sealing method used, it is important to ensure that a high level of optical clarity is maintained and that reflection of incident light from the base cover 6c or any adhesive used is minimized (especially in the area covering the detection chamber 20) to avoid adversely affecting subsequent analytical processes. Furthermore, the sealing process must be compatible with (and avoid interference with) any components of the sample container 6 (e.g., any drugs disposed therein). Specifically, it is desirable that no, or minimal, adhesives or other chemicals be exposed to the top surface of the base cover 6c within the fluidic system 64 to avoid potential contamination of the liquid sample during use. An additional layer 6d may be attached to the lower surface of the sample vessel 6 (see FIG. 9C), and may include the aforementioned barcode or other means of identification configured to be disposed on the angled portion 58a of the sample vessel 6.

[0092] Conveniently, the sample container 6 includes a sample receiving well 69 into which an appropriate volume of sample is placed, and contains a growth medium or culture medium 62 (FIGS. 9A, 9B) axially below the receiving well 69, which promotes the growth of bacteria in the sample fluid and is configured to be mixed with the sample after it is placed in the receiving well 69 of the sample container 6 and before it enters the common sample reservoir 60 (in which the growth medium or culture medium 62 itself is disposed) axially below the growth medium 62. Conveniently, in the illustrated embodiment, the growth medium is dried (e.g., lyophilized or freeze-dried). However, a liquid, concentrated growth medium may alternatively be used. In alternative embodiments, a powdered, dried growth medium may be used, which may facilitate rapid dissolution of the medium in the fluid sample. In some embodiments, the growth medium may be contained in a dissolvable capsule / pill.

[0093] In one embodiment, the sample vessel 6 is provided with a cover or cap 6a that can be attached to the vessel 6 for use. In the illustrated embodiment, the cap 6a includes an integral plunger or plug 6b and one or more protrusions 65 on the underside of the vessel plug 6b. When the cap 6a is engaged with the sample vessel 6, for example by threaded engagement, the or each protrusion 65 pierces the foil / film 67 covering the growth medium 62, thereby contacting the sample with the growth medium 62. When the cap 6a is further threaded into place, sealing the sample within the sample vessel 6, the plug 69 embeds at least a portion of the receiving well 69, forcing the sample and growth medium 62 into the common sample reservoir 60. It will be appreciated that the volume of the receiving well 69 and the extent to which the plug 6b can protrude into the receiving well 69 can be used to adjust the volume of sample and growth medium that is forced into the common sample reservoir 60. Furthermore, the amount / concentration of growth medium contained in the sample container 6 (before being mixed with sample) can be determined to provide a desired concentration of growth medium in the volume of sample / growth medium that is forced into the common sample reservoir 60. It should be noted that if the growth medium is contained in a dissolvable capsule or pill, there is no need to use a foil / film 67 to cover the growth medium, and therefore the protrusion 65 used to pierce this foil / film 67 may be omitted in such cases, if desired.

[0094] Once the sample and growth medium 62 are contacted and the cap 6a is attached, the sample container 6 can be inserted into the device 1 at the appropriate position. Preferably, as mentioned above, the sample container 6 is designed to be inserted into the device 1 in a specific orientation. Beneficially, the asymmetry of the sample container 6, i.e., in the illustrated embodiment, particularly the cutout segment 58 of the sample container 6, can be used to initially align the sample container 6 with the main optical support structure 28. Thus, in this orientation, the sample container 6 does not extend substantially through the cutout 30 of the optical support structure 28 when initially inserted into the device 1. In other words, the relative alignment of the cutout segment 58 and the optical support structure 28 guides the insertion of the sample container 6 into the device 1 and avoids potential damage to the device 1 and / or the sample container 6 as a result of improper alignment during insertion.

[0095] A programmed set of operations is initiated once the sample vessel 6 is inserted into the device 1. The effect of those operations on the fluid sample in the sample vessel 6 will now be described with reference to FIG.

[0096] As shown in FIG. 10A, each fluidic structure 64 and its associated detection chamber 20 constitute a substantially self-contained system within the sample container 6 (indicated by circle "A" in FIG. 10). Despite the presence of a common sample reservoir 60, centripetal / centrifugal forces during use prevent fluid flow between adjacent fluidic structures 64, thereby avoiding potential cross-contamination between the various drug-dosed sample portions to be analyzed separately in their respective detection chambers 20. Each fluidic structure 64 includes a first, radially extending "inlet" microchannel 66 (highlighted in FIG. 10A) that is in fluid communication at its outermost radial extent with a clarification (sedimentation) chamber or well 70, highlighted in FIG. 10C. The clarification chamber 70 is in fluid communication at its innermost radial extent with a second, generally U-shaped microchannel 68, highlighted in FIG. 10D, via a weir 70a (FIG. 10B). The second microchannel 68 has a pair of radially extending first and second flow path arms 68a, 68b configured to allow fluid flow along generally anti-parallel directions. The first flow path arm 68a extends between the clarification chamber 70 and an “air spring” or pneumatic (bypass) valve 72 (also known in the art as an “air spring” or “air ballast chamber”), highlighted in FIG. 10B, while the second flow path arm 68b extends between the air spring 72 and the detection chamber 20, highlighted in FIG. 10E. Suitably, in any embodiment of the present disclosure, each of the fluid flow paths 66, 68a, and 68b is generally radially arranged.

[0097] In this case, the term "air spring" is used to refer to a pocket of gas that can be configured to compress and place a fluid (liquid) under elevated pressure as it moves through the fluid flow path of the fluidic structure 64, thereby preventing fluid flow between the two flow arms 68a, 68b unless sufficient fluid force is applied to the gas. In other words, the air spring can provide fluid sealing and access control functions between different regions of the fluidic structure 64, for example, between the two flow arms 68a, 68b. Viewed another way, the movement of the sample fluid relative to the air spring 72 can be controlled by a pressure balance / difference; i.e., the centrifugal pressure difference caused by the rotating disk of the sample container 6 must overcome the elevated pressure (overpressure) caused by the reduced gas volume before liquid can pass through the air spring valve mechanism 72. However, it will be appreciated that alternative valve or sealing mechanisms could be utilized to provide corresponding functionality without departing from the scope of this disclosure.

[0098] Initially, to ensure thorough mixing of the sample and the growth medium 62 within the sample reservoir 60, the motor 10 rotates the sample container 6 alternately clockwise and counterclockwise (i.e., performs a reciprocating / oscillating motion) at an initial relatively slow speed (e.g., about 500 rpm or less) and for a predetermined period of time (about 30 seconds to about several minutes).

[0099] The sample vessel 6 is then rotated in one direction at an increased rotational speed, the speed used depending on various factors such as the geometry of the sample vessel 6, such that in some cases speeds up to about 1,600-1,900 rpm can be used, while in other cases, if greater centrifugal forces are desired, speeds up to about 2,600 rpm can be used. This generates sufficient centrifugal force to force the mixed sample out of the central sample reservoir 60, along each of the radially extending first fluid flow paths 66, and into each of the clarification chambers 70. This rotational speed is maintained for a predetermined period of time (e.g., about 30 seconds) to allow the sample to substantially fill each of the respective clarification chambers 70 and to apply sufficient centrifugal force to cause heavier particles (e.g., about 10 μm or larger) to settle around the outer periphery of the clarification chambers 70. Towards the completion of this high-speed spin cycle, enough sample fluid enters the clarification chamber 70 to raise the fluid level therein above the level of the weir 70a, and the overflowing fluid is displaced into the first flow path arm 68a of the second fluid flow path 68. Any sediment present in the sample fluid is disposed within the clarification chamber 70 and remains therein, such that the fluid sample entering the flow path 68 contains essentially only particles, e.g., bacterial cells, on the order of about a few microns or smaller. In practice, centrifugal forces acting on the liquid sample in use push heavier particles / unwanted impurities towards the radially outermost wall of the clarification chamber 70, thereby retaining them furthest from the weir 70a.

[0100] Once most of the fluid sample has been redistributed from the central sample reservoir 60 into the individual fluidic structures 64, the rotational speed of the sample container 6 is increased (the speed used will vary depending on various factors, including the geometry of the sample container 6, possibly speeds of, for example, greater than 1,900 rpm or greater than 2,600 rpm, and up to about 3,000 rpm, 3,600 rpm, or 4,000 rpm). This provides sufficient centrifugal force for the sample fluid flow to overcome the pressure exerted by the air spring 72 and enter the second microchannel arm 68b of the second fluid flow channel 68. Once the "seal" (pressure block) of the air spring 72 is overcome in this manner, the sample fluid can flow through the second microchannel arm 68b and enter the detection chamber 20. This process of directing the sample fluid from the clarification chamber 70 to the detection chambers 20 can take, for example, up to about 20 seconds to ensure that sufficient sample fluid enters each detection chamber 20 while avoiding the possibility of antibiotic contamination of the main fluid reservoir 60 (described in more detail below).

[0101] In the illustrated embodiment, a particular type and concentration of drug (antibiotic) is present in each detection chamber 20. Conveniently, the drug / antibiotic is in dry form, for example, as a result of being initially placed on the base of the detection chamber 20 during manufacture of the sample container 6 and then dried thereon. However, as those skilled in the art will appreciate, other forms of drug / antibiotic may be used according to preference or suitability; for example, the drug may be disposed on paper (e.g., filter paper) disposed within a region of the fluidic structure 64 so as to be dissolved in the liquid sample, or the drug may be present in liquid form. Suitably, as the sample fluid flows into and fills the detection chamber 20, the sample fluid thereby mixes with the disposed drug to a desired concentration. Once sufficient sample fluid has entered the detection chamber 20, the rotational speed of the sample container 6 is preferably reduced (e.g., from about 4,000 rpm, 3,600 rpm, or 3,000 rpm to about 1,500 rpm) to retain the fluid sample within the detection chamber 20. Explained, by reducing the rotational speed, the air within the air spring 72 is free to expand again when there is less pressure on it. When this occurs, the fluid within the clarification chamber 70 is forced back into the first fluid flow path 66 and into the central sample reservoir 60. This creates an air barrier between the fluids within the detection chamber 20, so cross-contamination cannot occur. Furthermore, once the detection chamber 20 is evacuated, there is then no force pushing the liquid sample radially inward toward the air spring 72, preventing any backflow of fluid from the detection chamber 20. In this case, inertial mixing of the sample fluid to solvate each drug is carried out by rotating the sample container 6 forward and backward (i.e., alternating clockwise and counterclockwise rotation) for a predetermined period of time (about several minutes, e.g., three minutes) at a relatively low speed (e.g., about 1,300 rpm to 1,800 rpm).

[0102] The initial sample distribution step is now complete, and illumination, measurement, and analysis of the samples in their respective detection chambers 20 can begin. During this process, the motor 10 is configured to rotate the sample containers 6 at a relatively slow speed, for example, only about 100 rpm or 200 rpm. This process has been described in detail above and will not be repeated here.

[0103] Some additional details regarding aspects of the processing used to extract the desired signal, i.e., the portion of the measured signal corresponding to the light scattered by the bacterial particles in the sample, are described with reference to Figure 11. This figure shows three plots of detected signal intensity over time, illustrating the well-windowing approach used to extract the appropriate portion of the signal for analysis.

[0104] The inventors have noticed periodic peak features occurring in the detected signal intensity measured by the photodetector that are known to occur where the light from the light source impinges on the walls / edges of the detection chamber 20 and that have been determined to be due to increased scattering of the incident light by the interior walls of the detection chamber 20, rather than by the particles in the sample. Thus, FIG. 11 illustrates how these peak features can be utilized during signal / data processing to more accurately identify those segments of the measured intensity signal that correspond to the light passing through and scattered by the sample in the detection chamber 20. FIG. 11A (top graph panel) shows the measured scattered light intensity at the photodetector 26 as the sample container 6 rotates relative to the light source. The scattered light trajectory shown spans three detection chambers 20, namely, the three openings 18 in the sample carousel 8 and the solid regions on either side of them. Removal of the detected light intensity between collection chambers 20 / openings 18 leaves only the trace of the detected scattered light intensity for the area spanned by the three detection chambers 20, as shown in the middle graph panel (FIG. 11B). The processor can be configured to identify such periodically occurring peak features in the measured light intensity (as shown in FIGS. 11A and 11B) that are not due to the particles in the sample and extract the segments of measured intensity between adjacent peak features from the remainder of the signal (as shown in the lower graph panel, FIG. 11C), so that measurements and interpretations of scattered light intensity associated with only the extracted segments (corresponding to light scattering by the sample, not the edges of the detection chambers 20) can be performed to assay for bacterial growth. This can advantageously avoid performing processing on portions of the signal that contain large noise spikes and allow the signal to be amplified if necessary.

[0105] This approach provides improved noise reduction over the (relatively simpler) method of simply extracting measurements during which the "desired" signal is obtained using a predetermined "time window," i.e., extracting data for each sample at a predetermined time offset from the start of each new rotation of the sample vessel 6 within that predetermined period or "window." This is because small variations in motor speed will cause a misalignment between the predetermined "time window" and the actual signal corresponding to light scattered from the bacteria in the sample; i.e., the predetermined "time window" will "drift" over time relative to the actual desired signal. This also means that the "time window" for data extraction will overlap with the peak feature (resulting from scattering by the edge of the detection chamber 20, as described above), and the extracted signal will contain a greater amount of increased scattering from the edge of the detection chamber 20, resulting in a greater noise level. Such "drift" or mismatch between the extraction "time window" and the actual period within which the desired signal falls will be more pronounced in those samples measured toward the end of a rotation, as evidenced by the increased noise in the graph of region 4 (shown in FIG. 8). Note, however, that the well windowing technique described above could potentially be more easily implemented in terms of post-processing of the sample measurements, rather than as a mechanism for real-time extraction of specific signal segments for processing. Additional or alternative mechanisms for reducing the noise in the extracted signal have also been developed, which allow for more accurate identification of the "window" within which the desired signal from each detection chamber 20 falls, and which are described in more detail below in connection with FIGS. 12A and 12B.

[0106] Figure 12A provides a bottom perspective view of the sample carousel 8 and in conjunction therewith provides further details of the calibration aspects of the intensity measurement process, and Figure 12B provides a close-up view of the sample carousel 8 as well as the controls used during this calibration.

[0107] 12A, the sample carousel 8 includes an additional calibration ring or gear 80 disposed on its underside and including a plurality of calibration features or teeth 82. In the illustrated embodiment, the calibration features 82 correspond to a plurality of spaced apart radially extending spokes projecting from the calibration ring 80, and each calibration feature 82 is positioned to interface with a corresponding one of the plurality of openings 18.

[0108] In use, when the sample container 6 is engaged with the sample carousel 8, each calibration feature 82 is thereby also associated with a corresponding one of the plurality of detection chambers 20 of the sample container 6. The apparatus 1 further includes a calibration reader or optical encoder 84 disposed within the apparatus 1 so as to be disposed adjacent the lower surface of the sample carousel 8 and configured, in use, to interface with each of the calibration features 82 in turn as the sample carousel 8 is rotated by the drive shaft 17. Specifically, the calibration reader 84 includes an optical arrangement configured to detect each calibration feature 82 passing therethrough, for example, by detecting a reduction or loss of optical signal caused by the calibration feature 82 passing through and temporarily blocking an optical beam path within the calibration reader 84 (as shown in more detail in FIG. 12B ).

[0109] The calibration reader 84 can be used to detect each calibration feature 82 associated with a respective opening 18 on the sample carousel 8 as the calibration feature 82 is associated with one of the detection chambers 20 and send a signal to the controller / processor of the device 1 to begin measuring scattered light intensity for a predetermined period of time after detection of the calibration feature 82 and for a predetermined period of time sufficient to encompass the period during which the detection chamber 20 blocks the light from the light source 22 without striking the walls of the detection chamber 20 (i.e., a sufficient interval to obtain the reading illustrated in FIG. 11C ). Beneficially, in this manner, the light scattering measurement window is reset multiple times per rotation of the sample container 6 to ensure that the photodetector reading is properly synchronized with the detection chambers 20. It will be appreciated that the number of calibration features can be selected according to preference, for example, there may be a calibration feature associated with each opening 18 in the sample carousel 8, or there may be one calibration feature associated with a given group of openings 18 (e.g., one calibration feature 82 for every two, three, four, five, or six, etc. openings 18).

[0110] Alternatively, the calibration features 82' may take a different form. For example, as in the illustrated embodiments of Figures 2, 3A, and 3B, the calibration features 82' take the form of ridges, fins, or flags spaced around the periphery of the sample carousel 8 and extending substantially downward from the base of the sample carousel 8 (as shown in those figures). As such, these ridges 82' may be molded into and form an integral part of the sample carousel 8. In this case, the calibration reader 84 may instead be mounted and oriented such that the vertically extending ridges 82' pass through the optical arrangement of the calibration reader 84. 3A and 3B, one calibration feature 82′ is coupled to each opening 18 of the sample carousel 8 such that passage of each calibration feature 82′ through the optical arrangement of the calibration reader 84 constitutes a trigger for reading or measuring the scattered light obtained from each corresponding detection chamber 20. Beneficially, this helps to prevent the drift that occurs within the “window” due to variations in motor speed, since a specific indicator is associated with each opening 18 and therefore each detection chamber 20.

[0111] FIG. 13 shows plots of detector intensity output as a function of time for the device of FIG. 1 , illustrating the signal-to-noise ratio achievable using the calibration features 82, 82′ and calibration reader 84. As in FIG. 8 , the device 1 is divided into four regions or quadrants, and the four plots represent the detector intensity measurements obtained from the detection chambers 20 disposed in the corresponding regions. Note that no antibiotics or other drugs were placed in the device when generating the detector intensity output plots of FIG. 13 , and therefore (as expected) the plots do not show any significant decrease in detector intensity output, as would be expected if the bacteria present in the sample clearly demonstrated susceptibility to the antibiotic (as in the plots of FIG. 8 ). However, what is clear from the plots of FIG. 13 is the significant reduction in signal-to-noise variation observed in all cases; i.e., the plotted detector intensity is relatively constant across all four regions, with no signal regions showing increased noise across any of the other regions (as in region 4 of FIG. 8 ).

[0112] It is envisioned that, optionally, the calibration reader 84 (or a processor associated with the light detector 26) may be configured to calculate the time interval between adjacent calibration features 82 passing through the reader 84 and compare the calculated interval with the predetermined interval over which the intensity of collected scattered light is measured. If there is a discrepancy between the measured "calibration" time interval and the predetermined measurement time interval, and if the discrepancy exceeds the predetermined time interval, the processor may be configured to change the measurement time interval to match the "calibration" time interval. This ensures that the intensity measurement is made when the detection chamber 20 is precisely aligned with the incident beam axis, i.e., when the light from the light source enters substantially through the center of the detection chamber 20.

[0113] Many modifications can be made to the above-described embodiments without departing from the scope of the present disclosure, which is defined in the appended claims.

[0114] For example, the drug need not be provided in the detection chamber 20, but instead could be disposed in a different portion of the fluidic structure 64, such as in the second flow arm 68b of the second microchannel 68. Additionally or alternatively, a second pneumatic valve or air spring may be provided at a location in the flow path after the detection chamber to allow for a different mechanism for effective mixing of the sample and the drug (via "sloshing" back and forth between a pair of air springs).

[0115] Additionally, note that the structure of the sample vessel 6 may be modified to change the optical path length of the light passing through the detection chamber 20 by changing the depth of the detection chamber well. Increasing the optical path length will increase the signal; i.e., the light will pass through more sample and interact with more bacterial particles in the process. Possible example path lengths are 4-10 mm (e.g., 4, 6, 8, or 10 mm well depths); changing the optical path length would also involve changing the size of other features in the fluidic system 64, such as the clarification chamber 70 and the air spring 72.

[0116] Other mechanisms for improving the signal-to-noise ratio include "masking" the edges of the detection chamber 20, for example, by attaching a thin film or sheet of plastic or other thin material to the base of the sample container 6 to prevent light from entering or interacting with other parts of the sample container 6; i.e., for example, the diameter of the opening 18 in the sample carousel 8 may be smaller than the diameter of the detection chamber 20.

[0117] Furthermore, detection sensitivity can be increased by making (optional) minor modifications to the optical configuration 2 to increase the signal-to-noise ratio of the detected scattered light. For example, the second photodetector 48 that collects unscattered light can be tilted or angled with respect to the path of the unscattered light beam to reduce unwanted reflection of this unscattered light back into the optical system (where it can interact with other light beams). Optionally, the first photodetector 26 can be shielded to reduce unwanted detection of stray light within the optical system.

[0118] As will be appreciated, minimizing the number of (separate) machined parts of the optical assembly can improve the accuracy of the light beam output from the light source 22 and its alignment with the aperture 46 of the detection chamber 20 and the light collector 24 when the optical assembly is assembled. Furthermore, in some cases, and particularly when the light source is in the form of a laser (diode), the laser can be housed in a machined / easily replicable laser block to improve consistency regarding the position of the laser beam when performing measurements (and thus improve the ease of maintaining good alignment within the optical system).

[0119] In connection with maintaining consistent alignment of the light beam through the optical system, additional sensors (such as accelerometers) can be incorporated into the apparatus 1 to measure vibrations occurring within the apparatus 1 (e.g., as a result of the motor 10 rotating the sample container 6 and / or the fan 42 in the temperature control module 14). This can help ensure that any vibrations are kept within / below acceptable limits to avoid adversely affecting the alignment of the components in the optical configuration 2.

[0120] Finally, an alternative configuration for the sample vessel 6' is also contemplated, as shown in Figure 14. From this figure, it can be seen that the relative positions of the clarification chamber 70' and detection chamber 20' in this alternative sample vessel 6' differ from the relative positions of the clarification chamber 70 and detection chamber 20 in the sample vessel 6 shown in Figure 10. Specifically, in the sample vessel 6 of Figure 10, the radially outermost extent of the clarification chamber 70 is located at a greater distance from the central rotational axis of the sample vessel 6 compared to the radially outermost extent of the detection chamber 20. However, in the alternative sample vessel 6', the reverse configuration is used, i.e., the radially outermost extent of the detection chamber 20 is located at a greater distance from the central rotational axis of the sample vessel 6' than the radially outermost extent of the clarification chamber 70'. 14 advantageously increases the ease with which the fluid sample can be retained within the detection chamber 20′ for illumination and measurement, because the centrifugal forces acting on the fluid tend to move the fluid toward the radially outermost extent of the fluid system 64. It will be appreciated that such adjustments to the relative position of the detection chamber 20 may require some consequential changes to the relative positions of the components of the optical configuration 2 to maintain the alignment of the light source 22, detection chamber 20, light collection aperture 46, and photodetectors 26, 48.

Claims

1. 1. An apparatus comprising an optical instrument for monitoring bacterial growth in a liquid biological sample to which a drug has been administered, the apparatus comprising: a sample vessel port for receiving, in use, a sample vessel, the sample vessel having at least one detection chamber for receiving a sample into which the drug has been administered; The optical instrument comprises: a light source configured, in use, to emit light along an incident beam axis that intersects at least one detection chamber of the sample container and to illuminate the drug-dosed sample contained within the detection chamber; a first photodetector configured to receive light scattered by bacteria in the sample; A light-collecting configuration, collecting light exiting the detection chamber that has been scattered in a forward direction by bacteria in the sample within a scattering angle range of about ±4 degrees to ±20 degrees relative to the incident beam axis, and directing the collected scattered light to the first photodetector; and a light collection arrangement configured to block unscattered light traveling parallel to the incident beam axis and exiting the detection chamber from reaching the first photodetector; at least one processor, measuring the intensity of the scattered light received by the first photodetector; determining a corresponding representative amount or concentration of bacteria present in the sample based on the intensity of the scattered light; repeating the measuring and determining steps at a series of predetermined intervals to determine a change in the representative amount or concentration of bacteria present in the sample as a function of time; and at least one processor configured to determine a corresponding susceptibility of the bacteria in the sample to each drug; An apparatus comprising:

2. 2. The apparatus of claim 1, wherein only light collected within an angular range of approximately ±4 degrees to ±20 degrees relative to the incident beam axis is directed to and received by the first photodetector.

3. 3. The apparatus of claim 1, wherein the ranges of scattering angles of the collected scattered light are +4 degrees to +16 degrees and -4 degrees to -16 degrees relative to the incident beam axis.

4. The light collection configuration includes: (i) a concave elliptical reflector configured to collect and reflect only light within an angular range of approximately ±4 degrees to ±20 degrees relative to the incident beam axis toward the first photodetector for receipt by the first photodetector; or 4. The apparatus of claim 1, further comprising: (ii) a concave elliptical reflector configured to collect and reflect forward scattered light within an angular range of approximately ±4 degrees to ±20 degrees relative to the incident beam axis toward a collector, the collector configured to receive light reflected by the concave elliptical reflector and focus the received light onto the first photodetector.

5. 5. The apparatus of claim 1, wherein the light collection arrangement comprises a concave elliptical reflector shaped to reflect the forward scattered light from the sample to the first photodetector or collector, the concave elliptical reflector being aligned with the incident beam axis and comprising an aperture configured to allow unscattered light from the detection chamber to pass through the concave elliptical reflector.

6. 6. The apparatus of claim 1 , wherein the optical instrument further comprises a second photodetector configured to receive unscattered light, optionally the second photodetector being positioned on an opposite side of the light collecting arrangement to the sample and aligned with the incident beam axis to receive the unscattered light.

7. the focusing arrangement includes first and second focusing lenses and a mirror; the first collecting lens is configured to direct the scattered light towards the second collecting lens and to focus unscattered light traveling along the incident beam axis onto the mirror; the second collecting lens is configured to receive the scattered light from the first collecting lens and to focus the scattered light onto the first photodetector; 4. The apparatus of claim 1, wherein the mirror is positioned along the incident beam axis between the first and second collecting lenses and is configured to reflect the unscattered light away from the first photodetector.

8. 8. The apparatus of claim 7, wherein the mirror is configured to reflect the unscattered light towards a second photodetector, the second photodetector being configured to receive the unscattered light from the mirror.

9. 9. The device of claim 1, further comprising a sample vessel carousel positioned within the sample vessel port to engage a sample vessel and configured to align a detection chamber containing at least a portion of the biological sample in the sample vessel with the incident beam axis of the light source of the optical instrument.

10. 10. The apparatus of claim 9, further comprising a motor operably coupled to the sample vessel carousel and configured to rotate the carousel to periodically bring a detection chamber containing at least a portion of the biological sample into and out of alignment with the incident beam axis of the light source.

11. 11. The apparatus of claim 9 or claim 10, wherein the sample vessel carousel is configured to engage with a sample vessel having a plurality of detection chambers, and the sample vessel carousel is configured to rotate to sequentially align and move each of the plurality of detection chambers of the sample vessel into and out of alignment with the incident beam axis of the light source.

12. 12. The apparatus of claim 9, wherein the sample vessel carousel comprises one or more openings configured to align with the one or more detection chambers of the sample vessel when the sample vessel is properly engaged with the sample vessel carousel in use.

13. 13. The apparatus of claim 9, wherein the sample vessel carousel includes one or more detectable calibration features for determining the position and / or orientation of the sample vessel carousel relative to the incident beam axis of the light source.

14. 14. The apparatus of claim 13, comprising a calibration feature reader that communicates with a processor of the apparatus to determine, in use, the time interval between detection of a calibration feature by the calibration feature reader and an associated detection chamber being aligned with the incident beam axis of the light source.

15. The processor of the optical instrument (i) interacting with a first photodetector to measure the intensity of the scattered light received by the first photodetector during a predetermined time window corresponding to a period during which a detection chamber of the sample vessel is aligned with the incident beam axis of the light source; or 15. The apparatus of claim 14, wherein (ii) the length of the predetermined interval is adjusted based on detection of the or each calibration feature.

16. 16. The apparatus of any one of claims 1 to 15, wherein the processor of the optical instrument is programmed to periodically repeat measuring the intensity of the scattered light received by the first photodetector and determining a corresponding representative amount or concentration of bacteria present in the sample as a function of time over a period of about 20 minutes to about 2 hours, about 20 minutes to about 1.5 hours, about 20 minutes to about 1 hour, or about 30 minutes to about 1 hour.

17. 17. The apparatus of any preceding claim, further comprising a temperature control system for controlling the temperature of the air inside the apparatus.

18. 18. The device of claim 17, further comprising at least one heating element and, if necessary, at least one airflow regulator configured to, in use, direct warm air into contact with a sample container received within the sample container port of the device to maintain a desired temperature of the biological sample in the detection chamber.

19. 19. The device of claim 17 or claim 18, comprising a pair of heating elements, each operably coupled to a fan for, in use, pushing warmed air towards the sample vessel port to heat sample in the detection chamber of a sample vessel received in the sample vessel port of the device.

20. The apparatus according to any one of claims 1 to 19, wherein the light source of the optical instrument is, for example, a laser light source of 620 nm to 780 nm.

21. 21. An apparatus according to any preceding claim, wherein the predetermined interval corresponds to approximately 0.6 seconds at a rotational speed of 100 rpm.

22. 22. The apparatus of claim 1, wherein the processor of the optical instrument is configured to identify a plurality of regularly occurring peak features in the measured light intensity, and to perform the measuring and determining steps only between adjacent peak features.

23. 1. A system for monitoring bacterial growth in a liquid biological sample to which a drug has been administered, the system comprising: The device of any one of claims 1 to 22; and a sample container comprising a plurality of detection chambers, each detection chamber configured to receive a medicated liquid biological sample, the system comprising: The system further comprises a sample positioning mechanism configured to sequentially align each of the plurality of detection chambers with the incident beam axis so that the light source illuminates the drug-administered liquid biological sample contained in the illuminated detection chamber.

24. 24. The system of claim 23, wherein the sample positioning mechanism comprises a rotating or carousel mechanism configured to rotate the sample vessel to sequentially align each of the plurality of detection chambers with the incident beam axis.

25. 25. The system of claim 23 or claim 24, further comprising a support structure configured to support the optical instrument, the support structure having an opening configured to receive a portion of the sample vessel comprising at least one of the plurality of detection chambers, such that when the portion of the sample vessel is positioned within the opening, at least one of the plurality of detection chambers can be positioned along the incident beam axis between the light source and the light collector.

26. 26. The system of any of claims 23 to 25, further comprising a temperature control system configured to maintain the temperature of the liquid biological sample at a temperature between 35° and 37°.

27. 27. The system of claim 26, wherein the temperature control system comprises a heating arrangement comprising a heating element configured to generate heat, and an air circulation system configured to distribute the generated heat evenly across the plurality of detection chambers of the sample vessel.

28. 28. The system of claim 27, wherein the circulation system comprises at least one recirculation duct and an associated fan configured to induce airflow across the heating element.

29. 1. A method for determining the susceptibility of bacteria in a sample to a drug, comprising: placing a medicated liquid biological sample in a detection chamber of a sample container; illuminating the sample in the detection chamber with light emitted by a light source along an incident beam axis passing through the detection chamber; collecting, with a light collecting unit, light scattered by interactions with bacteria in the sample, the light being scattered in a forward direction within a scattering angle range of ±5 degrees to ±20 degrees relative to the incident beam axis; focusing the collected scattered light onto a first photodetector by the light collecting unit; measuring, by a processor, the intensity of the scattered light received by the first photodetector and a corresponding representative amount or concentration of bacterial particles present in the sample; repeating, by said processor, said measuring step at a series of predetermined intervals; determining, with the processor, a change in the representative amount or concentration of bacteria present in the sample as a function of time; determining, by the processor, the susceptibility of the bacteria in the sample to the drug used to administer the sample based on the determined change in the representative amount or concentration of the bacteria in the sample as a function of time; A method comprising:

30. The sample container includes a plurality of detection chambers, at least two of the plurality of detection chambers containing samples administered with different drugs, and the method includes: sequentially positioning each of the plurality of detection chambers containing the drug-dosed sample in light emitted along an incident beam axis; performing each subsequent step of the method for each of the plurality of detection chambers; determining the relative susceptibility of the bacteria in the sample to each drug used to administer the sample to identify the most effective drug for use in a therapeutic treatment regimen; 30. The method of claim 29, comprising:

31. The sample container includes a plurality of detection chambers, at least two of the plurality of detection chambers containing samples administered with the same drug at different concentrations of the drug, and the method further comprises: sequentially positioning each of the plurality of detection chambers containing the drug-dosed sample in the light emitted along an incident beam axis; performing each subsequent step of the method for each of the plurality of detection chambers; determining the relative susceptibility of the bacteria in the sample to each concentration of drug used to administer the sample to identify the most effective drug concentration for use in a therapeutic treatment regimen; 30. The method of claim 29, comprising:

32. collecting, by a second photodetector, unscattered light passing through the or each detection chamber parallel to the incident beam axis; comparing the intensity of the unscattered light collected by the second photodetector with the intensity of the scattered light collected by the first photodetector for the same detection chamber; 32. The method of any of claims 29 to 31, comprising:

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