Patent Application
20210146361
The present invention relates to an apparatus for conducting an assay, and particularly to an apparatus which is capable of controlling the movement of magnetic beads through microfluidic chambers and/or channels in so called “lab-on-a-disc” systems.
“Lab-on-a-disc” or “lab-on-a-CD” systems use generally disc-shaped reaction vessels, although other geometries may be used, containing passages, cavities and other features such as valves and zones of altered hydrophobicity. They are particularly useful for carrying out biological assays involving microfluidic transfers and reactions within the discs. The assay discs are used with apparatus which effects rotational movement to control the flow of reaction fluids using centrifugal forces.
Microfluidic systems are of increasing importance in the field of medicinal and molecular diagnostics applications, and are of particular interest due to their high surface/volume ratios, short diffusion parts and minimal reagent volumes, leading to microfluidic systems being of particular interest for time critical applications and field diagnostics. In many applications, there is a need to separate and/or move components through micro-chambers and/or micro-channels in order to carry out diagnostic tests. In particular, there may be a need to separate and/or move target liquid and/or particulate solid-phase biomaterials of a biological sample through a microfluidic system.
Some known apparatuses for carrying out assays in microfluidic system, such as assay discs and the like, comprise means for transporting components between microfluidic chambers and/or channels by the use of magnetic beads housed within the micro-chambers and/or channels. Movement of such magnetic beads may be controlled by a combination of externally mounted magnets and/or spinning the assay disc housing the microfluidic system, in order to move the beads by centrifugal force.
Magnetic beads may be used to transport, mix, separate, and/or concentrate biological molecules and/or cells, for example, DNA, antibodies or bacteria, by forming interactions with desired biological components.
US 2013/0206701 discloses a system which utilises a stationary magnet to attract beads towards the centre of an assay disc and spinning of the assay disc to create a centrifugal force to move the beads towards the outer edge of the disc. Alternative disclosures include US 2008/0073546 which utilises a similar system for counterbalancing centrifugal and magnetic forces using either stationary magnets or magnets which may be moved across the radius of an assay disc while spinning. US 2008/0035579 and US 2008/0056949 also disclose the use of counterbalanced centrifugal forces and magnetic forces to manipulate movement of magnetic beads through a microfluidic system, with the magnet's position limited along a guide rail.
Other systems may use two fixed magnets at different radial distances, the first magnet attracting the beads towards the centre of the disc, the second magnet attracting the beads towards the circumference of the disc.
In each of these systems, precise control of the movement of magnetic beads is hindered due to the need to balance opposing forces. It is also the case that magnets may be unable to collect beads that are at the innermost and outermost areas of the fluid chambers. Furthermore, time delays may occur while the disc accelerates to the speed required to move the beads using centrifugal forces and, where chambers are housed at similar or identical distances from the centre of the assay disc, similar or identical centrifugal forces may be felt, making it difficult to direct the desired movement of the magnetic beads.
In such systems, the positioning of the interconnecting channels and/or chambers may be dictated by the positions of the fixed magnet or magnets. These design constraints may limit the utility and/or optimisation of the system.
The present inventors have recognised shortcomings with known apparatuses and have developed a new system which allows more controlled assay disc procedures and brings further advantages.
According to a first aspect, the present invention provides an apparatus for conducting an assay in a microfluidic system comprising magnetic beads, said apparatus comprising: a platform upon which a microfluidic system can be mounted, one or more actuators having a magnet, configured to directly influence movement of magnetic beads housed within a microfluidic system when said microfluidic system is mounted on said platform, and a control means configured to control the relative movement of the one or more magnets, and the microfluidic system when mounted, to enable the magnet to trace a desired path across a mounted microfluidic system, said magnet being positionable at any x- and y-coordinates of a mounted microfluidic system, wherein said apparatus further comprises: a) at least one rotary actuator configured to enable magnet movement in an x-axis, and/or b) a means for moving a mounted microfluidic system in a stepwise fashion.
Such an apparatus may be utilised with mounted microfluidic systems, and may be able to collect and transport beads from any position within a microfluidic system, including from the innermost and outermost regions of the chambers, channels and or mounted system. Accordingly, microfluidic chambers and/or channels may be optimally positioned with regards to the assay testing required, and without mind to the position of any fixed magnets and or centrifugal forces.
Such a system may also provide timely movement of magnetic beads.
According to a second aspect, the present invention provides an assay unit comprising an apparatus according to the first aspect of the invention.
According to a third aspect, the present invention provides the combination of an apparatus according to the first aspect of the present invention, or an assay unit according to the second aspect of the invention and a microfluidic system configured to be mounted on the apparatus.
According to a fourth aspect of the present invention there is provided the use of an apparatus according to any of the first, second or third aspect of the present invention.
According to a fifth aspect of the present invention there is provided a method for carrying out an assay comprising the steps of: i) mounting an assay disc comprising a microfluidic system on a turntable, wherein said microfluidic system comprises a plurality of magnetic beads; and i) providing a magnet on an actuator such that the magnet made be positioned at any x- and y-coordinates of the assay disc.
An embodiment of the present invention provides an apparatus for conducting an assay in a microfluidic system comprising magnetic beads, said apparatus comprising: a platform upon which a microfluidic system can be mounted, one or more actuators having a magnet, configured to directly influence movement of magnetic beads housed within a microfluidic system when said microfluidic system is mounted on said platform, and a control means configured to control the relative movement of the one or more magnets, and a microfluidic system when mounted, to enable the magnet to trace a desired path across a mounted microfluidic system, said magnet being positionable at any x- and y-coordinates of a mounted microfluidic system, wherein said apparatus further comprises: a) at least one rotary actuator configured to enable magnet movement in an x-axis, and/or b) a means for moving a mounted microfluidic system in a stepwise fashion.
A rotary actuator may result in arcuate magnet movement. It shall be understood that arcuate motion, unlike linear motion, necessarily comprises vector components in at least two axes. However, it shall be understood that the arcuate motion in along a particular axis, such as the x-axis, relates to the vector component of the arcuate motion along this axis. Accordingly, arcuate magnet motion along an x-axis requires that there be some movement of the magnet along the x-axis, but does not prevent there being additional magnet movement along a y-axis, or any other axis.
A rotary actuator may comprise a rotary actuator having an arc of large radius, wherein a magnet may be mounted upon such a rotary actuator and traverse a path in the x-y plane across a surface of a mounted microfluidic system. Preferably, the magnet may be mounted upon a rotary actuator and traverse a path in the x-y plane between the outermost edge of a mounted microfluidic system and a central point thereof. Alternatively, and/or in addition, a rotary actuator may be configured to move the magnet along a z-axis away from and towards the surface of a mounted microfluidic system.
The apparatus may be configured to hold a mounted microfluidic system in a fixed position, with magnet movable in at least two axes. Magnet movement in the x-axis is achieved by the use of one or more rotary actuators. Optionally, one or more linear or rotary actuators may additionally be used. In some options, magnet movement may additionally occur in the y-axis.
Alternatively, the apparatus may be configured to enable a mounted microfluidic system to move in or about at least one axis in a stepwise fashion, with the magnet moveable in at least one alternate axis.
According to some embodiments, when the apparatus comprises a means for moving a mounted microfluidic system, the system may be rotatable.
It shall be understood that stepwise motion relates to motion which is discontinuous, i.e. periods of motion separated by pauses or changes in the direction of motion.
According to some embodiments, the stepwise motion of a mounted microfluidic system may be achieved by non-continuous rotation. Optionally, the stepwise motion may be rotation about an axis in one direction, followed by rotation about the same axis in the alternate direction. Preferably each period of rotation in a single direction is less than 360 degrees of rotation. Optionally, each period of rotation may be from zero to 180 degrees, zero to 90 degrees, or zero to 30 degrees.
Alternative the stepwise non-continuous rotation may comprise rotation about an axis in a single direction, wherein the rotation is intermittently interrupted by pauses in rotation. Each period of rotation separated by a pause in rotation may be from zero to 360 degrees. Optionally, each period of rotation may be from zero to 180 degrees, zero to 90 degrees, or zero to 30 degrees.
Stepwise motion may also include discontinuous linear motion in one or more axes. Optionally, stepwise linear motion may include a period of motion along one axis followed by a period of motion along a second axis. Preferably said axes may be substantially perpendicular to each other.
It shall be appreciated that the terms x-axis, y-axis and z-axis relate to the axis of a microfluidic system when mounted on the apparatus of the present invention. Such microfluidic systems will have a high surface area plane, such as the flat surface of a microfluidic disc, which will be understood to be the x-y plane. The z-axis extends in a perpendicular direction to the x-y plane, i.e. the high surface area plane of microfluidic system when mounted.
For systems with four-fold rotational symmetry, the x-axis and y-axis may be used interchangeably. For disc shaped systems, the x-axis may be understood as extending along any axis corresponding to a radius of the microfluidic disc when mounted.
The present invention may be used with a microfluidic system of any shape. Preferably the microfluidic system will be predominantly flat. Suitable systems may be square, rectangular or disc shaped. Preferably, systems may be disc shaped.
Optionally, the apparatus may be configured to rotate a mounted microfluidic system, such as a microfluidic disc, about an axis. Where the apparatus is configured to rotate a mounted microfluidic disc about an axis, the magnet may be movable along, or predominantly along an axis corresponding with a radius of the microfluidic disc when mounted.
Optionally, when the apparatus comprises a means for moving a mounted microfluidic system in a stepwise fashion, the magnet may be mounted on a rotary actuator. Alternatively, or in addition, the magnet may be mounted on a linear actuator. Where a magnet is mounted on a rotary actuator, the resultant magnet motion may be arcuate.
According to some embodiments, the actuator may comprise a linear actuator. Such an actuator may be suitable for moving the magnet in any axis. Preferably, a linear actuator may be configured to move the magnet along an x-axis of a planar surface of a mounted microfluidic system, such as along the radius of a microfluidic assay disc.
Thus, controlled movement of magnetic beads housed within a mounted microfluidic system may be achieved by; movement of one or more magnets in one or more axes, accompanied by precise stepwise rotation of a mounted assay disc through an angle of less than 360 degrees, by the controlled stepwise movement of a mounted microfluidic system along one or more axes relative to the magnet, or by the use of a magnet mounted on a rotary actuator, in combination with a further linear or rotatory actuator and a fixed microfluidic system. Accordingly, the magnet may be positionable at any desired x- and y-coordinate of a mounted microfluidic system.
The present invention allows for more specific control of the movement of magnetic beads, and any liquid and/or particulate solids associated therewith, through the microfluidic channels and chambers of a mounted microfluidic system compared to previous systems which utilise centrifugal forces resultant from the spinning of a mounted microfluidic assay disc. Furthermore, the control means of the present invention enables the magnet to trace any desired path across a mounted fluidic system, which may not be achievable by systems which are spinning in order to produce and/or maintain a centrifugal force.
In some embodiments the apparatus may comprise a rotary actuator and a linear actuator mounted on a single drive shaft. Optionally, the linear actuator may control the x-position of the magnet relative to a mounted microfluidic system and the rotatory actuator may control the z-position of the magnet relative to a mounted microfluidic system.
By controlling the z-axis position of the magnet relative to a mounted microfluidic system, the position of the magnet may be optimised for each mounted microfluidic system, so as to be close enough to provide a strong interaction with any magnetic beads, while enabling the disc to rotate without the supporting platform interfering with the magnet and inhibiting apparatus and/or microfluidic system movement.
It shall be understood that the apparatus may optionally comprise multiple magnets. Where multiple magnets are used, each magnet may be housed on a separate actuator.
According to some embodiments, the one or more actuators may be configured to position the one or more magnets above the surface of a mounted microfluidic system. Alternatively, the one or more actuators may be configured to position the one or more magnets below the surface of a mounted microfluidic system.
Optionally, where a magnet is located above a mounted microfluidic system, the magnet may rest upon the surface of the microfluidic system under its own weight, with its own weight providing sufficient force to keep magnet in contact with the surface.
Alternatively, the one or more actuators may be configured to position the one or more magnets at a fixed distance from the surface of a mounted microfluidic system.
Where the magnet is located below a mounted microfluidic system, an upward force may be applied to the magnet to keep the magnet in contact with the bottom of the mounted fluidic system, or to constrain the magnet to be held at a fixed distance away from the lower surface of the mounted microfluidic system.
Where the apparatus comprises two or more magnets, these may be independently positioned above or below the microfluidic system.
According to some embodiments, the apparatus may comprise a means to move a magnet clear of the microfluidic device. Optionally, this may be achieved by rotation of the driveshaft about a z-axis.
In some embodiments, the one or more magnets may be mounted on a spring assembly configured to enable the one or more magnets to be capable of being brought into contact with the surface of a mounted microfluidic system. Optionally, the one or more magnets may be mounted on a leaf spring assembly.
Where additional clearance is required, for example, to allow a microfluidic system mounted on the apparatus to rotate without the supporting platform interfering with the magnet, the magnet may be mounted on an actuator suitable for moving the magnet in an x-axis, such as a linear actuator, wherein this actuator may be rotated away from and/or towards the mounted microfluidic device. Rotating the actuator rod in one direction will move the magnet clear of any obstruction while rotation in the other direction will enable the magnet to contact the disc. Optionally, the magnet may be mounted on a spring, such as a leaf spring, and a small additional rotation may flex the spring to provide the required upward pressure.
According to some embodiments, the one or more magnets may be mounted on an adjustable mounting assembly. Optionally, the adjustable mounting assembly includes at least one adjustable magnet holder and at least one through plate. The one or more magnets may be positioned within a holding portion of each one the adjustable magnet holders. In some embodiments, the one or more magnets are held in the holding portion, in a position above and/or below a microfluidic system mounted on the apparatus.
Optionally the through plate may be located on a portion of one of the rotary actuators. In one embodiment, the through plate may be located on a portion of one of the linear actuators. In a further embodiment, the through plate is located on a portion of the rotary and/or linear actuator. The through plate may be located on a driveshaft of the rotary and/or linear actuators.
In some embodiments, the through plate comprises a first engagement portion. In some embodiments, the adjustable magnet holder has a second engagement portion. The second engagement portion may be configured to engage with the first engagement portion of the through plate. For example the first engagement portion of the through plate may include a threaded portion, preferably a threaded through hole and the second engagement portion of the adjustable magnet holder includes a threaded portion that corresponds to the threading of the first engagement portion.
Thus, in some embodiments, the adjustable mounting assembly is configured to allow positioning of the magnet in a position along a Z-axis. This may be achieved by actuating the adjustable magnet holder, for example by clockwise or anticlockwise rotation of the adjustable magnet holder relative to the through plate, which can lead to the position of the magnet being altered by the threaded portion of the adjustable magnet holder travelling up or down along the correspondingly threaded portion of the through plate.
In certain embodiments, mounting the one or more magnets on an adjustable mounting assembly allows for fine tuning of the position of the one or more magnets in a z-axis in relation to a microfluidic system mounted on the apparatus. Thus allowing for a wider range of different microfluidic systems to be mounted and used with embodiments described herein.
According to some embodiments, the platform may comprise a turntable configured to receive and controllably rotate an assay disc comprising a microfluidic system. In particular, the turntable may be configured to be capable of controllably rotating a mounted assay disc through partial revolutions. Optionally, the turntable may be configured to be capable of rotating a mounted assay disc in both clockwise and anticlockwise directions. Thus, the apparatus may be capable of controllably rotating a mounted assay disc through a sequence of partial revolutions in a clockwise and/or anticlockwise direction. The apparatus may comprise a controller configured to control the one or more actuators and the turntable to enable the magnet to trace a desired path across a mounted microfluidic system. Optionally, the rotation of a microfluidic system and the movement of one or more actuators, upon which one or more magnets are mounted, may be simultaneously controlled.
The apparatus of the present invention may be suitable for use with an assay disc comprising one or more microfluidic chambers and one or more microfluidic channels. The microfluidic channels may be of any suitable orientation, geometry, and length. The microfluidic channels may comprise linear and/or arcuate sections, and may optionally comprise acute, obtuse, reflex or right-angled turns. Accordingly, the apparatus of the present invention enables the movement of magnetic beads through a path of any desired geometry, and is not limited to geometries which may be traversed by counterbalancing magnetic and centrifugal forces.
In some embodiments, the turntable may comprise one or more heater modules. Such heater modules may be configured to apply heat to one or more specific parts of a mounted microfluidic system. Preferably, the one or more heaters may be configured to apply heat to one or more specific parts of a mounted microfluidic system during rotation.
Optionally, the controller may be configured to control the heater modules. The control may be specific not only in terms of location to which the heat is applied, by conduction, but also in terms of the ramp up/ramp down time, i.e. the rate of change of temperature of reaction medium at a particular location on the disc.
The apparatus of the present invention can be configured so as to carry out isothermal assays (e.g. where the heater element is positioned substantially continuously across the whole area of the assay so that all of the assay is carried out at substantially the same temperature, or alternatively where no heat is applied). However, the apparatus of the present invention is perhaps even more useful when configured to carry out non-isothermal assays, i.e. where different parts of the assay disc, and therefore different parts of the reaction medium, are, or can be, subjected to different temperatures. The combination of targeted collection and transportation of magnetic beads, along with any liquid and/or particles associated therewith, and specific heating allows effective and tailorable operation.
Targeted heating of specific areas of a microfluidic system, accompanied by controlled transport of magnetic beads may also enable specific heating profiles to be achieved.
Unlike some prior art devices comprising heating elements within the assay discs, the heat comes from the turntable. Low amounts of power are required because the heat is specifically applied by conduction to specific parts of the assay disc, and the temperature can be adjusted quickly which can bring efficiencies not only in terms of the assay duration but also in terms of the amount of time it is necessary to use the heating elements.
Means may be provided to facilitate the correct positioning of the assay disc relative to the turntable. For example, the turntable may comprise a central spindle corresponding to a spindle hole in the assay disc. A longitudinal groove on the spindle and a corresponding longitudinal projection on the hub of the assay disc enable the angular position of the assay disc to be fixed relative to the turntable. Guiding means may be provided to guide the assay disc to the correct angular position. For example, the horizontal dimension of the groove of the spindle and the horizontal dimension of the complementary projection on the disc may decrease in a longitudinally downward direction: this means that when the disc is just above the turntable there is some tolerance in the angular positioning of the assay disc relative to the turntable, this tolerance decreases as the assay disc is lowered to the turntable.
Further means may be provided to locate the assay disc relative to the turntable. For example, a locating projection (e.g. a pin or boss) and corresponding locating recess (e.g. a hole or cut away portion) may be provided on the turntable and assay disc respectively, or vice versa. These locating features may be located at or near the periphery of the assay disc.
Thus, there may be two or more means of locating the angular position of the assay disc relative to the turntable. For example, the central spindle locating means may act as a stationary locator and guide means, and the projection and recess features at or near the periphery of the assay disc may act as more precise locating means.
Clamping means may be provided to secure the assay disc to the turntable.
These clamping means may comprise a mechanical ball bearing clamping mechanism to hold the assay disc to the turntable, for example at the central hub.
Alternatively or additionally, the clamping means may comprise magnetic means for holding the assay disc in a fixed position relative to the turntable. A magnetic means may also be used to align and guide the disc to the correct position. Therefore, for example, a user may place the disc above the turntable and the apparatus will then automatically align the disc and securely hold it to the turntable in the correct position.
This may enable the assay disc to me mounted at a particular position, such that the relative positions of the microfluidic chambers and/or channels may be known. Consequently, it may be possible to precisely control the rotation of the disc from a known starting position in order to collect and transport magnetic beads through a desired portion of the microfluidic system.
The magnetic means may comprise disc magnets arranged in opposite pole directions in the turntable (for example in the hub of the turntable) and disc magnets arranged in opposite pole directions in the assay disc (for example in the hub of the assay disc).
Wireless power transfer means may be used to transfer power to heater elements in the turntable and/or to a heater controller. One possible power transfer mechanism may comprise disc coils arranged in a concentric manner. The apparatus may comprise a stationary disc coil and a rotational disc coil. For example, a stationary disc coil (which may be fixed below the turntable) may be energised to generate an alternating electromagnetic field that will then induce current on a rotational disc coil (which may be fixed to the turntable and above the stationary disc coil separated with a small gap).
The apparatus may also comprise an IR (infrared) transceiver for bi-directional communication. The IR bi-directional communication may be used to allow instructions and heating parameters to be transferred to a heater controller wirelessly and may also allow communication from the heater controller to the host by establishing handshake between the host and the heater controller. Each transceiver may optionally comprise one or more IR emitters and one IR receiver. Preferably, the IR transceiver may comprise, four IR emitters.
The four IR emitters may be arranged in equidistance surrounding the central hub of the turntable. The total field of emission from the four IR emitters allow the IR receiver at the opposite end to be able to receive the IR emitted signal across 360°, so that communication can be made regardless of the turntable position.
The present invention thus provides heat to the assay disc whilst it is spinning. This heating can be provided in a continuous manner and/or the heating can be tailored.
A known problem which may occur in assay discs concerns the condition of the liquid when it is being heated. Bubbles may appear and/or there may be expansion of the air and/or pressure difference between chambers may have undesirable consequences, e.g. causing back-flow of liquid. The distorted condition of the liquid can affect the assay e.g. by affecting optical readout. The present invention brings advantages in restoring the original state of the liquid in the reaction wells through centrifugal rotation whilst heating the liquid. Thus, the present invention avoids compromising the heating of the liquid, and consistent optical readout can be obtained.
The heater modules may for example be foil heaters.
The turntable may be mounted with one or more heater modules, optionally two or more heater modules. In some embodiments, the turntable may be mounted with 3 or more heater modules.
The apparatus comprises circuitry for controlling a number of heater modules that could be controlled independently to heat up to the target temperature. The heaters may consist of a thin aluminium plate for evenly distributed heating across specific region(s) of the assay discs. An RTD (resistance temperature detector) may be mounted on the thin aluminium plate to monitor the temperature of the aluminium plate. The RTD may be connected to the heater controller circuit to provide feedback to regulate the heater to achieve stable temperature over time.
The wireless functionality may be present in terms of the power generation in order to power the circuitry and the heaters, and wireless communication may also be used with 360° IR transceiver configuration. The wireless features allow the turntable to be spun freely, at the same time the power can be supplied to operate the heaters and the IR communications.
The heater modules may be configured to protrude from the surface of the turntable using light spring pressure so as to be in contact with the assay disc so that heat can be transferred effectively.
Optionally, insulators may be used beneath the heater modules to prevent heat loss downwards. As a result, they can improve the efficiency of heat transfer and the control of the heating rate.
In one embodiment there are two heater modules on the turntable: one may be used for heating up the sample in the sample chamber; and the other may be used for the reaction wells for an assay. Additional heater modules may be added for other heating requirements: for example, an additional heater could be used to assist fluid transfer by generating differential pressure that would allow the fluid to transfer from a heated area to a cold region.
In such cases, the heating of a region in a chamber or reaction well would increase the enclosed pressure which is caused by the expansion of the gas components. In order to stabilise the overall pressure inside the apparatus, the pressure must be released in some means either through a release to external atmosphere or by pushing any liquids in the next chamber(s) to equilibrate the pressure. Subsequent cooling of the chamber or well causes the contraction of the gas components and therefore reduces the internal pressure resulting in movement of liquid into the chamber or well.
A stationary coil assembly may contain a stationary coil attached to a ferrite sheet sandwiched between two holders which may conveniently be made of plastic. The same configuration may be used for a rotational coil assembly. The stationary and rotational coil configurations may be used to provide the power to the heaters. The generated power (e.g. 5 Watts and above) could be customised according to the application needs by changing the configurations of the stationary and rotational coils, and/or the signal frequency supplied to the stationary coil. For example, the power generated and delivered to the heater and controller could be adjusted to between 5 Watts and 7 Watts by adjusting the frequency of signals supplied to stationary coil. The power may be used to drive the heaters and the associated circuitry including the IR transceiver and the heater controller. In a further example, the power may be configured to be distributed between heaters, e.g. to a 4 Watt heater and a 2 Watt heater operating at the same time.
The whole turntable assembly may be attached to the spindle of a motor to establish the rotational movement on the turntable for controlling the movement of the fluid. In this example, a BLDC (Brushless DC) motor may be used. The motor may be mounted on a metal base (motor mount) which is fixed to the chassis. On top of the motor mount, the stationary IR (Infrared) transceiver board may be mounted and followed by the stationary coil. Both components may be mounted so that they are held stationary. Above the stationary coil are the rotational coil and the circuit board for the rotational IR transceiver and heater controller. They may be mounted to the turntable. They could be spun along with the turntable without interrupting the power supply and IR communication between the host and heater controller.
According to some embodiments, the present invention provides an assay unit comprising an apparatus according to the first aspect of the present invention.
The assay unit may provide a chamber in which the apparatus according to the first aspect of the present invention may reside. The assay unit may be provided with a means for controlling one or more aspects of the environment within the chamber. Aspects that may be controlled include, but are not limited to, temperature regulation, humidity regulation, atmospheric pressure, composition, such as oxygen level regulation and the like. Optionally, the chamber may be provided with a means for temperature regulation.
In some embodiments, the assay unit may comprise a means for heating and/or cooling the ambient temperature of the chamber within which the assay disc is located during the assay. Thus, whereas the stationary heating system provides localised heating from the turntable, an optional rotational heating system allows the temperature of the environment around the assay disc (and, consequently, the assay disc and its contents) to be altered. Optionally a fan heater or cooler may be used. For example, an air blower, using a fan, may be used.
According to some embodiments, the present invention provides the combination of an apparatus according to the first aspect of the present invention, or an assay unit according to the second aspect of the present invention, and a microfluidic system configured to be used with such an apparatus or assay unit.
The microfluidic system may be an assay disc, and may be mounted on the platform of the present apparatus, such as a turntable. Suitable assay discs, may comprise microfluidic channels and or microfluidic chambers. Magnetic beads may be housed in one or more of the microfluidic chambers and/or channels.
According to some embodiments of the present invention, there is provided the use of apparatus according to the first aspect of the present invention.
In use, a microfluidic system may be mounted on an apparatus according to the present invention. Such microfluidic systems might be incorporated in an assay disc, a rectangular block, or any other suitable format. The microfluidic system may comprise microfluidic channels and/or chambers, one or more of which may house a plurality of magnetic beads.
In disc-based systems, use of the apparatus may include one or more magnets being moved substantially radially using a linear actuator mechanism or a rotary actuator having an arc of large radius, the centre of which is on a line at right angles to the midpoint of the line between the innermost and outermost positions of the magnet. Movement concentric to the circumference is implemented by controlled rotation of the disc about its axis. By combining the two motion components, the effective path of the magnet can trace any desired locus.
Alternatively, for disc or non-disc-shaped systems, the effective motion can be achieved by arcuate movement of the magnet, optionally in addition to further linear or rotary movement of the magnet along an alternate axis whilst the microfluidic system is held in a fixed position. In another option a disc or non-disc-shaped system may be moved in a step-wise fashion accompanied by linear and/or rotary movement of one or more magnets in another direction, preferably the magnet movement may be predominantly at right angles to the system movement.
Thus, for systems of the present invention, the x and y coordinates of the magnet may be varied continuously with respect to the microfluidic system.
The magnet may be moved to any position within the parameters of the microfluidic channels and/or chambers in order to collect and/or transport magnetic beads. Controlled relative movement of the magnet relative to the microfluidic chambers and/or channels, enables transportation of the beads through the microfluidic system at any radial distance from the disc centre.
Use of the present invention may enable magnetic beads to be transported along concentric channels, channels of varying radial distance, channels of varying gradient within the microfluidic system, and through channels and/or chambers situated at any position in the microfluidic system.
Accordingly, use of the apparatus of the present invention enables optimised microfluidic system design, without the need to position its chambers and/or channels in close proximity to a fixed magnet or magnets. Similarly, the microfluidic flow path is not restricted to paths which may be easily traversed by magnetic beads directed by centrifugal forces, stationary magnets, or a combination of the two.
According to a fifth aspect of the present invention, there is provided a method for carrying out an assay comprising the steps of: i) mounting an apparatus comprising a microfluidic system on a turntable, wherein said microfluidic system comprises a plurality of magnetic beads; and ii) providing a magnet on an actuator such that the magnet may be positioned at any x-coordinates of the assay disc.
According to some embodiments, there is also provided a step of moving a plurality of magnetic beads through a portion of the microfluidic system by moving said magnet whilst rotating said assay disc such that said magnet traces a desired locus in x-, y-plane of the assay disc.
The present invention will now be described in further, non-limiting, detail, with reference to the following Figures in which:
With reference to
The range of movement of the magnet 3 may be limited such that the magnet may only be positioned along a portion of the radius of a mounted microfluidic disc corresponding to regions where a microfluidic channel or chamber may be present. Alternatively, the range of movement of the magnet may extend across the entire radius of a mounted microfluidic disc.
In particular, the controller controls the rotation of the mounted assay disc 5 in a clockwise and/or anticlockwise direction, as required, while simultaneously controlling the movement of the linear actuator in order that the magnet may trace a path between chambers 8 via the channels 9. Magnetic beads housed within a chamber 8 or channel 9 are attracted to the localised magnetic field caused by the proximity of the magnet and are directed through the chambers and/or channels, mirroring the path of the magnet 3.
The channels may be angled such that they run parallel to the circumference of the assay disc, or are angled thereto. The channels may also comprise curves and bends 9a.
In an alternative embodiment, depicted in
As depicted in
As shown in
The linear actuator 2a enables the magnet to be moved along a desired x-axis along the radius of a mounted microfluidic disc.
A leaf spring, 12, may apply a suitable force to keep the magnet 3 contact with the assay disc 5.
As shown in
The adjustable mounting assembly comprises a through plate 22 and a magnet holder 25. The through plate may be mounted onto the drive shaft 10 of one or more linear 2a and/or rotary actuators 2b/2c. The through plate 22 may be located so as to be positioned above the assay disc 5. The through plate 22 comprises a first engagement portion 24 which is configured to engage with a second engagement portion 26 of the adjustable magnet holder 25. The adjustable magnet holder comprises a holding portion 27 where the magnet 3 is engaged and held in place.
The holding portion 27 may be a recess where the magnet 3 is inserted. The magnet 3 may be held in the holding portion 27 by magnetic force. In some embodiments the magnet 3 may be held in the holding portion 27 by one or more clips or engagement members. In some embodiments the holding portion may have the spring located above the magnet 3 within the recess so as to provide a suitable force to keep the magnet 3 in contact with the assay disc 5.
In some embodiments the first engagement portion 24 may be a threaded though hole and the second engagement 26 may be a correspondingly threaded protrusion, as shown in
When the male treaded portion is inserted into the female threaded portion or vice versa, the threads engage with each other. This allows for the adjustable magnet holder 21 and the magnet 3 held therein to be maintained in a fixed position above the assay disc 5. The adjustable magnet holder comprises an actuator portion 35 that allows for the adjustable magnet holder 25 to be rotated as shown by arrow 34. Rotation may be clockwise or anti-clockwise and depending on the arrangement of the threaded portions allows the second engagement portion to travel in the Z-axis relative to the assay disc 5 along the first threaded portion 24 leading to movement of the magnet 3 according to arrow 36 as shown in
With reference to
The turntable platter 112 comprises a central spindle 18 which itself comprises a longitudinal groove 110 which functions as an inner guide feature to allow coarse alignment of an assay disc 5 onto the spindle 18. Turntable platter 112 comprises boss 1112 which acts as a finer alignment feature.
The magnetic means of locating and securing the assay disc 5 to the turntable platter 12 are shown most clearly in
The magnet assemblies 114 and 1104 are conveniently positioned at the hub of the apparatus, and accordingly in the embodiment shown, this magnet assembly 1104 has hole 1106 corresponding to spindle hole 1102 of the assay disc.
A side view and a perspective view of a turntable in accordance with the present invention are shown in
With reference to
Some of the components of the turntable are shown in
| Number | Date | Country | Kind |
|---|---|---|---|
| 1711804.3 | Jul 2017 | GB | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/GB2018/052054 | 7/20/2018 | WO | 00 |
