Patent Application
20220008924
The present invention relates to devices, systems, and processes useful as automated interfaces for centrifugal microfluidic platforms.
Lab-on-a-chip (LOC) devices have become central to a number of applications, which include point-of-care diagnostics, genomic and proteomic research, and the detection of pathogenic agents, among other things. These miniaturized systems offer many advantages over conventional instrumentation since they provide a plausible mean for controlling the flow of liquids, minimizing the consumption of sample and reagents, increasing reaction times, performing multiplex analysis with a high degree of parallelization, while reducing hands-on engagements and associated risks of contamination. In addition, these systems offer a suitable path toward portability, remote operation, and a relatively low cost per assay. Fluidic structures can be produced with sub-micrometer resolution in a variety of materials while flow in these systems can be induced, sustained and controlled using both external and internal pumping, valving and actuation schemes.
The world-to-chip interface is an important aspect of all LOC devices, as it largely determines how they are conceived with respect to design, fabrication, and functioning. The world-to-chip interface can fulfill several different functions, which all translate to some form of connectivity between the microfluidic device and bulk components at the periphery such as reservoirs, pumps, or valves. A world-to-chip interface is mainly used to mediate the exchange of reagents, samples, and products of reactions which includes their transfer from an external source onto the chip as well as their recovery from the chip. As a dispensing unit, it must offer a plausible solution for solving the mismatch that exists between volumes that can be processed at the macroscopic level (sometimes in the milliliter range) and those that are prevalent at the chip level (microliters to hundreds of microliters). Moreover, the world-to-chip interface provides an effective means for applying pressure to selected sites on the device using an external pump. LOC devices that use integrated sensor elements based on electrochemical, optical, or magnetic principles often need to be powered from an external source and therefore require an interface that is adequate to these ends (e.g., by incorporating magnets, optical fibers, or electrical interconnects). Regardless of its constitution and intended use, an interface generally must be reliable, convenient to operate, and preferably low-cost. The development of suitable world-to-chip interfaces is a particular challenge for centrifugal LOC systems since the scenario of a rotating chip considerably limits the options that are available for these platforms. The inventions disclosed herein include the automation of fluid dispensing into microfluidic devices in the context of centrifugal microfluidic platforms.
One of the main issues that currently limits the widespread use of LOC systems is the lack of standards with respect to interfacing and connecting microfluidic devices in order to dispense fluids onto the chip. To this end, most systems rely on custom solutions that are developed for a specific application which is performed inside a standard laboratory setting. Many of these solutions still involve manual intervention such as pipetting or some sort of plugging which is time consuming, can damage the chip, or may cause leakage. While few standard formats exist (e.g., Luer Locks), they are not universally applicable and can be fabricated only in a relatively small range of materials (e.g., thermoplastic polymers).
Current protocols for standard bioassays such as ELISA (enzyme-linked immunosorbent assay) involve robotic or manual dispensing of various reagents, many of which are available commercially (e.g., Qiagen QiaCube, etc). Furthermore, in most academic settings and commercially available products (e.g., Abaxis Piccolo XPress), centrifugal microfluidic cartridges are loaded by manually or robotically pipetting via inlet holes using pipettes or syringes.
Therefore, loading of microfluidic devices (including both rotating and stationary systems) is typically performed by using a pipette to insert the reagents and buffers one at a time through access ports. Each liquid is pipetted into reservoirs on the chip which typically contain, in addition to the loading access port, a vent to evacuate air while the liquid is loaded. This process is done manually at the beginning of the assay and typically takes a few minutes. Although manual feeding by the operator is still widespread across the LOC community, it is of limited practical value for applications outside a standard laboratory setting. This is especially important when low amounts of volume need to be dispensed with high precision in a repetitive manner.
Centrifugal microfluidics has the advantages of simple operation, almost zero dead-volumes and the possibility to perform complex on-chip protocols while in rotation. When in automated mode, they are however handicapped in the case of applications requiring large volumes (such as buffers, other reagents) by the lack of metering capabilities to dispense precise amounts of liquids onto the chip while in rotation.
Reagents and buffers can also be inserted on the chip during the manufacturing stage of a microfluidic device. To confine the liquids and avoid evaporation, this is typically achieved by encapsulating the reagents and buffers in sealed blisters. The blisters are then opened by the end user just before the assay, for example, by using structures integrated in the holders of the device. Alternatively, in centrifugal microfluidics, the blisters can be designed to burst only when a specific rotation frequency is reached. While solving several limitations of manual pipetting, blisters also have drawbacks.
Recently, some of the inventors herein have proposed a method to automate the loading of reagents in the centrifugal microfluidic devices from external storage reservoirs. This system is based on a centrifugal platform with integrated lines that can be pressurized while the platform is rotating at high speed. Using these pressure lines, liquid can be transferred from external containers placed on the centrifuge to the microfluidic device. The external containers can have volumes much larger than those of the microfluidic reservoirs on the chip, thus enabling loading of various buffers and reagents for multiple sequential tests and minimizing the need for manual interventions. This method also allows for transferring liquids from the microfluidic device to an external waste container, making it possible to perform assays with volumes that exceed the capacity of the microfluidic device at once. Thus, this method removes the need for integrating on-chip reservoirs for buffers, reagents, and waste, which provides the possibility to greatly simplify the design of the microfluidic devices and reduce their size and fabrication cost. The external containers required for an assay can be assembled in a cartridge and the connections from the microfluidic device to the external containers can be realized by using an array of standard connectors (e.g., Luer Lock) placed on top of this cartridge. The end user can then simply clip the microfluidic device to this cartridge, greatly reducing the number of manual steps required to setup an assay. However, reagent and waste fluids have to be accommodated on the rotor of the platform, which limits the applicability in many applications requiring large volumes of reagents.
Pipetting is not practical outside of laboratories where high precision pipettes are not always available. While not very complex, the process of pipetting liquids inside a microfluidic device is not necessarily straightforward and often requires some training. Training of end users is not always possible or practical (e.g., in point-of-care applications). Even after training, user errors during pipetting are common and can lead to unexpected failure of the assay.
The liquids may reach undesired locations inside the microfluidic device during pipetting. For example, priming of siphon or capillary valves due to pipetting problems is a common problem in centrifugal microfluidics. Also, the pipetted liquid can touch the vent hole of the reservoir before the required volume is transferred. In this case, the air may not be able to escape reliably from the reservoir, which can then force some liquid out of the reservoir through the vent hole. Structures can be integrated inside the reservoirs of the microfluidic devices to guide the liquids during pipetting. This however increases fabrication complexity and is only mildly effective for liquids having a low contact angle with the materials of the microfluidic device.
Pipetting of highly wetting reagents (such as oils and organic solvents) is typically very challenging. The low contact angle of these liquids promotes capillary action, which can transfer the liquid to unwanted locations (e.g., outside target reservoir, etc.).
Pipetting of solutions with high viscosities is not precise with standard pipettes and requires special equipment that is not always available to the end users.
The pipetting process can leave traces of reagents, buffers, or samples around the access holes of the microfluidic devices. During centrifugation, these liquids can create contamination of the device and the platform. This can also cause health and safety issues when pathogenic samples or dangerous reagents are being used.
The time required for pipetting becomes problematic when multiple assays are performed in parallel or when the number of reagents and buffers required for a particular assay is large.
In some centrifugal microfluidics assays, the access holes used to load the liquids must be blocked after the pipetting step, adding another manipulation that requires time and can lead to failure of the assay when not performed properly by the operator.
In centrifugal microfluidics, the reservoirs of the microfluidic devices must be large enough to accommodate all the reagents and buffers required for an assay. The space required by the reservoirs and wastes typically occupies a very large fraction of the overall area available on the microfluidic device, limiting the space available for the assay. The space occupied by the reservoirs also has a large impact on the total dimensions of the microfluidic devices, therefore increasing fabrication cost. Alternatively, some reservoirs can be replenished multiple times during an assay. However, repeated manual interventions are not practical and often defeat the purpose of automation.
The limited space available on the microfluidic devices also limits the maximum volume that can be stored for each reagent. This is particularly problematic for assays requiring very large volumes of wash buffer (e.g., Elisa assay, etc.).
As discussed briefly above, long-term reagent stability is often problematic in blisters, limiting shelf life of the microfluidic devices or forcing storage at low temperatures. For some reagents, it is often possible to improve stability by drying. The dried reagent is then inserted on chip along with a blister pouch filled with a resuspension buffer. Achieving uniform resuspension of the dried reagents upon release of the liquid can, however, be difficult and often requires implementation of complex mixing protocols.
The integration of blisters increases fabrication complexity, cost, and development time of the microfluidic devices.
Entirely emptying the blisters can be challenging, which can be problematic when the assay requires precise liquid metering. Additional structures can be integrated on the microfluidic device to perform metering, but this increases the space requirement.
The size of the blisters and associated reservoirs must be large enough to accommodate all the reagents and buffers required for an assay. As described previously, this increases the size and cost of the microfluidic devices. Also, assays requiring large volumes or a large number of different solutions are difficult to implement with blisters.
Achieving high reliability for the operation of the blisters requires high control of the manufacturing conditions. This is particularly true when the blisters are designed to release the liquids at a specific rotation frequency.
Automated reagent loading from external containers is only available for centrifugal microfluidic platforms with pneumatic control, such as the one disclosed in WO 2015/132743. As stated above, limitations in applications requiring large amounts of liquid reagents and waste fluids are inherent
Transfer of precise volumes of liquid from the external container to the microfluidic device is challenging to achieve with pressure-based control. Metering channels with tight fabrication tolerances must be integrated in the microfluidic devices. The level of liquid in the external container, the rotation speed of the platform, and the liquid viscosity must also be taken into account to achieve precise metering. Errors in metered volumes can affect outcome of the assay and its reproducibility.
Running multiple tests simultaneously is challenging with automated reagent loading from external containers. Indeed, one set of external reservoirs is required for each assay ran concurrently. The size and weight of the external containers therefore grow rapidly with the number of concurrent tests. While on-chip multiplexing is possible (i.e., having several tests performed in each microfluidic device), it complicates chip design and liquid metering. Also, when the platform is designed to run multiple assays concurrently, it is necessary to block or otherwise deactivate the unused sets of external containers to avoid liquid spills from the locations that are not coupled to a microfluidic device.
All the external containers required for the assays must be placed on the rotating platform. The combined weight of the rotating liquids put additional stress of the rotating platform, increasing its size, weight, complexity, and cost. Balancing of the rotating platform can also be difficult to achieve when large volumes are stored in several different groups of external containers.
The cartridge with the containers and standard connectors (e.g., Luer Lock) must be precisely manufactured to ensure leak free operation.
There thus remains numerous unmet needs in automated LOC design and use.
Automated loading methods and systems, into assay-specific centrifugal microfluidic cartridges, as described herein are thus designed to address some or all the aforementioned limitations in the field. In performing an automated bioassay, certain conditions must be met while maintaining reproducibility: (i) the ability to store and exchange reagents, (ii) operability with minimal conservative volumes and waste generation while maintaining throughput (e.g., reasonable processing times and the possibility of performing tests in a multiplex format), and (iii) outfitting the platform for various bioassays (for, e.g., not limited only to a certain type of ELISA).
According to a first aspect of the invention, a system useful for delivering liquid to a microfluidic chip comprises a centrifugal microfluidic platform including a rotatable rotor configured to receive at least one lab-on-chip on a top surface of said rotor, and a stationary liquid pumping system positioned adjacent to said centrifugal microfluidic platform, said liquid pumping system comprising at least one stationary nozzle positioned above said rotor top surface for dripping liquid into said microfluidic chip when mounted on said rotor top surface, without any physical contact or coupling between said at least one nozzle and said microfluidic chip.
In such a system, the centrifugal microfluidic platform can comprise an articulated centrifugal platform.
In such a system, the centrifugal microfluidic platform can comprise a powered centrifugal platform.
In such a system, the liquid pumping system can comprise a peristaltic pump.
In such a system, the liquid pumping system can comprise a pneumatic pump.
In such a system, the liquid pumping system can comprise a syringe pump.
In such a system, the liquid pumping system can comprise a piezoelectric pump.
According to another aspect of the invention, a microfluidic lab-on-chip comprises a chip body, a loading chamber formed in the chip body, a large diameter loading port formed in the top of the loading chamber which exposes the loading chamber to the exterior of the chip body, and at least one fluidic channel formed in the chip body in fluid communication between the loading chamber and the exterior of the chip body.
In such a lab-on-chip, the loading port can have a diameter of at least D+2E, were D is the diameter of a liquid drop to be loaded into said loading chamber and E is the imprecision in angular positioning of a microfluidic platform upon which said lab-on-chip is to be positioned.
In such a lab-on-chip, the loading chamber can have a floor coated with a hydrophilic material to enable droplet spreading.
In such a lab-on-chip, the hydrophilic material can be a microstructured or/and nanostructured material.
In such a lab-on-chip, the nanostructured material can be embossed on the floor of the loading chamber.
In such a lab-on-chip, the hydrophilic material can comprise a sheet of absorbent paper or an absorbent membrane.
In such a lab-on-chip, the chip body can be disc-shaped.
Such a lab-on-chip can further comprise a metering channel formed in said chip body fluidly connecting said loading chamber to the exterior of said chip body, said metering channel for metering precise amounts of liquids before transferring out of said loading chamber.
Such a lab-on-chip can further comprise a reaction chamber formed in said chip body, a fluid channel formed in said chip body directly fluidly connecting said loading chamber to said reaction chamber, and an exit channel formed in said chip body directly fluidly connecting said reaction chamber to the exterior of said chip body.
Such a lab-on-chip can further comprise an exit channel formed in said chip body directly fluidly connecting said loading chamber to the exterior of said chip body.
According to yet another aspect of the invention, a method of aligning multiple stationary liquid dispensing nozzles of a liquid pumping system with multiple loading ports on a microfluidic chip using an articulated microfluidic platform with two degrees of freedom comprises rotating said platform while retaining said chip on said platform about a primary axis and generating a driving centrifugal force field, and rotating said chip about a secondary axis offset from said primary axis to change an orientation of said chip with respect to said centrifugal force field.
According to yet a further r aspect of the invention, a combination comprises a microfluidic chip as set forth above, an articulated centrifugal microfluidic platform, wherein the platform can rotate about an axis, a stationary waste collector having a cavity, the waste collector positioned away and separated from the microfluidic chip, and a chip holder mounted to said platform and retaining said microfluidic chip.
In such a combination, the microfluidic chip can be positioned on the chip holder such that the at least one fluidic channel opens toward the waste collector.
In such a combination, the microfluidic chip can have channel openings on an edge thereof adjacent to said waste collector only such that, in a first orientation, liquid in said microfluidic chip is indefinitely retained in the microfluidic chip, and in a second orientation, liquid in said microfluidic chip can exit the microfluidic chip towards said waste collector.
Such a combination can further comprise liquid absorbent material in said waste collector.
In such a combination, the absorbent material can be paper based.
In such a combination, the absorbent material is fabric based.
In such a combination, the absorbent material is a porous polymer.
In such a combination, the waste collector comprises a 3D design which inhibits liquid from exiting the waste collector.
According to yet another aspect of the invention, a combination comprises a microfluidic device as set forth above, a centrifugal microfluidic platform including a plurality of dispensing nozzles, and a stationary ring-shaped waste reservoir.
Still other aspects, features, and attendant advantages of the present invention will become apparent to those skilled in the art from a reading of the following detailed description of embodiments constructed in accordance therewith, taken in conjunction with the accompanying drawings.
The invention of the present application will now be described in more detail with reference to exemplary embodiments of the apparatus and method, given only by way of example, and with reference to the accompanying drawings, in which:
Referring to the drawing figures, like reference numerals designate identical or corresponding elements throughout the several figures.
The singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a solvent” includes reference to one or more of such solvents, and reference to “the dispersant” includes reference to one or more of such dispersants.
Concentrations, amounts, and other numerical data may be presented herein in a range format. It is to be understood that such range format is used merely for convenience and brevity and should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited.
For example, a range of 1 to 5 should be interpreted to include not only the explicitly recited limits of 1 and 5, but also to include individual values such as 2, 2.7, 3.6, 4.2, and sub-ranges such as 1-2.5, 1.8-3.2, 2.6-4.9, etc. This interpretation should apply regardless of the breadth of the range or the characteristic being described, and also applies to open-ended ranges reciting only one end point, such as “greater than 25,” or “less than 10.”
The subject matter described herein provides world-to-chip interface apparatus and methods for centrifugal microfluidic platforms. It can be also used in conjunction with any type of centrifugal microfluidic platforms or lab on a chip instruments, and can be particularly advantageous when implemented with articulated centrifugal platforms as disclosed in WO 2015/181725. An articulated centrifugal microfluidic platform allows the microfluidic chips mounted on it to rotate about a secondary axis while the platform is spinning at high speed, changing in this way the orientation of the microfluidic chip with respect to the centrifugal force.
In general terms, a world-to-chip interface apparatus as described herein can include a liquid pumping system that transfers metered amounts of biochemical reagents from large stationary reservoirs to chambers on microfluidic chips mounted on centrifugal microfluidic platform, such as an articulated centrifugal platform (see, e.g., WO 2015/181725). The pumping system can make use of any type of liquid actuation principle such as peristaltic, pneumatic, or others for which the amount of liquid transferred to the chip can be accurately controlled. Alternatively, syringe-type pumps, in which the pump chamber and reservoir are integrated together, and a piston and plunger are moved by a suitable linear actuator or motor or the like, can also be used.
An element that can be very important in many implementations is that the transfer is realized without any physical coupling or contact between the liquid dispensing nozzle and the chips, but is instead achieved by dripping small droplets of liquid from one or more dispensing nozzles. These dispensing nozzles are situated at the end of a feeding tube placed vertically above the rotation plane defined by the microfluidic chips. The microfluidic chips include a special microfluidic chamber capable of receiving liquids from the dispensing nozzle through a designated opening with a diameter larger than the size of individual droplets dripping from the nozzles. The size of the droplets are, in turn, dependent on the liquid being dispensed and the geometry of the nozzle's opening, both of which are known quantities for any particular liquid and dispensing system, and thus the diameter of the opening into the chip's chamber can be mathematically predetermined, or determined empirically.
In one aspect of the invention, the centrifugal microfluidic platform is operated in three modes: (i) the loading mode, where the rotor is stopped and the microfluidic chips are aligned at predefined positions for liquid transfer from the dispensing nozzles, (ii) the reaction mode, where the platform rotor is either spinning at high speed or stopped at a random position for incubation, where the microfluidic chip is performing various steps of the biochemical assay and, (iii) the unloading mode, where the liquids are extracted from the chip and sent to an external waste chamber.
In a loading mode, the microfluidic platform stops at predefined angular positions to align the chips with the dispensing nozzle and a metered amount of liquid is transferred from the external stationary reservoirs to specially designed loading chambers on the chips. The loading of these microfluidic chambers on several independent chips can be done in parallel using multiple dispensing nozzles simultaneously aligned with the chambers. However, to minimize the number of nozzles and the complexity of the pumping system, it is preferable that multiple chambers on multiple chips are loaded through the same nozzle. This can be achieved by sequentially aligning the microfluidic chambers of all the chips with the nozzle using the rotation of the platform.
In a reaction mode, the platform rotor starts spinning at high speed and the liquids are transferred to the appropriate reaction chambers through centrifugation. In the case of the articulated centrifugal microfluidic platform, the orientation of the microfluidic chip can also be changed within certain limits to transfer liquids internally from chamber to chamber or to perform special microfluidic steps such us mixing or enhanced capture. The platform can also be stopped for incubation steps as the design of the chip allows for maintaining liquids in the reaction chamber for a relatively long period of time.
In an unloading mode, one or more liquids are removed from the microfluidic chips and sent to a waste reservoir. In the case of the articulated centrifugal microfluidic platform, the microfluidic chips are placed in a special orientation with respect to the waste chamber such that one or more liquids from the microfluidic chips are expelled through channels having openings at one of the microfluidic chip edges. This step is performed at high speed only and the design of the chip, as well as its orientation relative to the centrifugal field, are chosen such that efficient transfer of liquid droplets from the microfluidic chip to the waste reservoir is achieved with no liquid loss in between.
In another variant, the microfluidic devices are replaced by a disc with equivalent microfluidic circuitry having a central liquid receiving chamber with an opening at the center of the disc and on the platform main rotation axis. The dispensing nozzles are placed above the opening of the central reservoir which is large enough to accommodate all required dispensing nozzles directly above the opening. In this embodiment, the liquid loading from the dispensing nozzles can be performed without having to align the microfluidic device or even to stop the rotation of the platform as the opening of the central reservoir remains aligned at all time with the dispensing nozzles during the rotation of the platform. The central reservoir might be part of a single circular disk-like microfluidic device or might be connected to several independent microfluidic devices with tubing. Metering structures can be integrated in the central reservoir to ensure uniform distribution of the dispensed liquid to all the microfluidic devices or to several locations inside a disk-like microfluidic device. An advantage of this embodiment is to reduce the number of operations that must be performed for the dispensing process, which can greatly speed-up the assay when a large number of microfluidic devices must be filled. It also reduces the risk of misaligning the microfluidic devices with the dispensing nozzles following hardware issues. However, in this embodiment, all the liquids must transit through the same centrally located reservoir, which can potentially cause cross contamination issues for some assays.
From a microfluidic perspective, a potentially important element of the subject matter of this disclosure is the design of waste-free microfluidic chips that enable the transfer of large volume of liquids from the dispensing nozzles to small microfluidic chips and from these chips to the waste after the reaction is done. The new type of microfluidic circuits proposed here includes a chip where at least one channel is opened to the surrounding air, providing a way to empty the microfluidic chips. Although similar approaches have been proposed (see, e.g., U.S. Pat. No. 8,444,934 B2), the one described here is different from several points of view. First, in the case of the articulated centrifugal platform, the openings of the microfluidic channels are designed at the proximal edge (with respect to the rotation center) and not at the distal edge of the chip as in U.S. Pat. No. 8,444,934 B2. This is enabled by the additional degree of freedom provided by articulated microfluidic platforms which allow for changing the angle of the chip with respect to the centrifugal force and pointing the channel openings preferentially either toward the waste or away from it. A second difference includes the fact that, instead of a waste which is part of the microfluidic disc and rotates with it, a stationary waste is provided as a part of the instrument case, coupled to an external large reservoir which can accommodate large amounts of liquid waste. A third and last difference lies in the fact that, because the microfluidic chips cannot rotate with respect to a secondary axis, the channels openings described in U.S. Pat. No. 8,444,934 B2 are always pointed toward the waste and the liquids cannot be maintained inside the reaction chambers on the chip indefinitely, as is the case in the devices described herein.
The waste reservoir is generally decoupled from the microfluidic chip and placed nearby to collect the waste liquids expelled from the microfluidic chip. The waste reservoir can also be placed on the rotating holder close to the microfluidic device instead of being stationary, collecting the liquid dripping from multiple channels/chips at a time. The waste reservoirs typically have a large opening for receiving the liquids from the chip(s) and can be eventually be filled with liquid absorbent material to prevent splashing and undesired liquid displacements.
While the interruption of microfluidic channels through openings to the surrounding air is typically used as a way to send the reaction products to the waste, it can also be provided more upstream as well. For example, a secondary channel connected to an opening can be used to precisely meter the liquid transferred from a dispensing nozzle by sending excess liquid directly to the waste. This metering process can be performed just after dispensing, before the liquid is transferred and processed in the microfluidic device. This can be used to circumvent the intrinsic imprecision of the droplet-by-droplet dispensing of the dispensing nozzles (i.e., volume transferred cannot be controlled more precisely than the volume of a droplet).
The implementation of waste reservoirs decoupled from the microfluidic chips can reduce the size of the microfluidic chip drastically, which can be a very interesting advantage for commercialization. The apparatus and methods described herein also enable the use of large amounts of liquids on small microfluidic chips, which is paramount for highly sensitive bioassays such as ELISA, requiring a large volume of wash buffer.
In this description, the term “articulated centrifugal microfluidic platform” is intended to include centrifugal microfluidic platforms with articulations between chip holders and rotors, that is, the microfluidic chips/holders are provided with an additional degree of freedom in a form of a controlled rotation with respect to a secondary axis. Examples of this type of platforms are described in more detail in WO 2015/181725 and Geissler, M., et. al., “Microfluidic Integration of a Cloth-Based Hybridization Array System (CHAS) for Rapid, Colorimetric Detection of Enterohemorrhagic Escherichia coli (EHEC) Using an Articulated, Centrifugal Platform”, Anal. Chem., 2015, 87 (20), pp 10565-10572.
The term “classical microfluidic platform” is intended to include any centrifugal microfluidic apparatus having a simple rotor with holders for a microfluidic disc or chips and where the rotor is coupled to a motor in order to induce rotation of the microfluidic disc or chips with respect to the axis of this motor solely.
The term “pneumatically actuated centrifugal microfluidic platform” is intended to include centrifugal microfluidic platforms with miniature pumps and valves integrated on the rotor to pneumatically control flows in microfluidic devices. Also, centrifugal platforms where the actuation pressure is transferred to the rotation platform (to the microfluidic devices) through rotary unions are also included. Examples and detailed descriptions of such platforms can be found in WO 2015/132743 and Clime, L., et al. “Active pneumatic control of centrifugal microfluidic flows for lab-on-a-chip applications”, Lab Chip 2015 (The Royal Society of Chemistry, 2015)
Preferred embodiments of the apparatus and methods are described in greater detail in the following.
A first preferred embodiment relates to an apparatus for performing automated microfluidic assays and includes a combination of an articulated centrifugal microfluidic platform and a stationary liquid pumping system capable of loading aqueous solutions into microfluidic chips by dripping through dispensing nozzles without any physical contact of coupling between the nozzles and the microfluidic chips.
The centrifugal platform includes has a rotor 200 with articulated holders 201 which can accommodate microfluidic chips 300 and can rotate about a secondary axis different from the main rotation axis 103.
The centrifugal platform also has a stationary waste collection system 400 in a form of a ring that surrounds the edge of the rotor and is coupled with a waste reservoir 403 via a tube 402.
More specifically, as illustrated in
According to an exemplary embodiment, the waste collector 400 includes a cavity 401, which is preferably annular, formed in a ring-shaped body 405, and a collection tube 402 for sending the waste liquids to a large external reservoir 403. The microfluidic chips 300 are contained by the centrifuge rotor 200 in special holders 201 which can have a controlled rotation about a secondary axis parallel to, but different from, the main rotation axis of the main motor spindle, as described in greater detail elsewhere herein.
Although only four holders with one microfluidic chip per holder are illustrated in this
As shown in
The mechanism 204 can be any active mechanism which allows control of angular orientation with desired speed and accuracy such that a step motor, a DC motor with an arc spring, a squiggle motor, and the like. However, in a preferred embodiment the actual mechanism is a passive one and includes a holder with the center of mass M displaced away from the secondary rotation axis 203 as illustrated in
Thus, the second preferred embodiment illustrated in
The hole 302 has a diameter of at least D+2E, were D is the diameter of the liquid drop and E is the imprecision in angular positioning of the microfluidic platform, both of which can be determined empirically for the specific nozzle, liquid, and platform control system.
With continued reference to
The other substrate 311, used for closing the reaction chamber 303, may also be coated directly and/or have a strip/insert 312 coated with functional biochemical material, such as an antibody.
The microfluidic chips in
After a specific reagent liquid has been consumed or used in the reaction, the holders 201 are oriented at 180 degrees with the openings 306 and openings 202 pointing toward the waste and the platform starts spinning at a specific angular speed in order to push the liquids towards the openings 306 and transfer the liquid into a waste reservoir 400.
In a first exemplary embodiment, the waste reservoir is part of the instrument case, as a stationary ring with a cavity to collect the waste and direct it to the hole 402 and a collection tube 403 (e.g.,
Thus, cross-sectional views of the complete assembly of the platform, including the rotor 200 with holders 201, the microfluidic chip 300, and the stationary waste 400, are illustrated in
After the introduction of liquid 601 through the hole 302, the liquid is found in an indeterminate configuration in the loading chamber 301. When the platform starts spinning, the liquid 601 is transferred through the channel 307 (
It can be particularly advantageous to use an embodiment in which each liquid necessary for the performed assay is pumped into the chip by using individual liquid pumping units, as illustrated in
In another embodiment, the pumping system can be provided with one or more valving mechanisms which selectively direct all the inlets to one single outlet 503, as illustrated in
Thus, in this exemplary embodiment, the pumping system is mounted directly on the lid 700 of the platform 10, and the tubing 701 connecting the dispensing nozzle to the liquid reservoir 502 is coupled through an electromechanical valve 702. The cover lid 700 slides up and down using one of several sliders 703 to allow access to the platform rotor. The liquid can be transferred from the liquid reservoir(s) 502 to the dispensing nozzle by gravitational action.
In another embodiment, the liquid pumping system is based on pneumatic actuation, where the liquid is extracted and transferred to the microfluidic chips by pressurizing the reservoirs 502. An electromechanical valving 702 system controlled by the electronic control unit 102 can be used to synchronize the valves with the pneumatic actuation protocol and the assay performed on the microfluidic chip. In this pneumatically driven embodiment, one or more gas lines is (are) connected to the reservoir(s) 502, which introduce air or another gas into the open headspace of the reservoir, thus pressurizing the reservoir; upon opening of the valve 702, the fluid in the reservoir 502 is driven into the tube 701 and into the chip, as described elsewhere herein. While air is a preferred gas to use in this embodiment, other gases or mixtures of gases can be selected, particularly those which do not react with the liquid being delivered to the chip.
In accordance with yet another embodiment, microfluidic chips can be constructed with more than one, that is, several loading chambers, as depicted in
More specifically, in the embodiment of
To increase throughput, rotors with multiple holders can be constructed, as illustrated in
In yet another exemplary embodiment, the waste cavities 711 on the microfluidic chip holders include multiple interconnected chambers and channels or multilevel three-dimensional structures to take advantage of both centrifugal force and gravity and send liquids irreversibly into a waste collection reservoir.
The loading chamber 801 is positioned at the center on the rotation axis 104. The liquid can be transferred while the disc 800 is either at rest or rotating at high speed. The disc 800 can also contain several microfluidic circuits that are fed with necessary reagent liquids from the same chamber 801, as illustrated in
Any of numerous types of pumps can be used in the numerous embodiments herein, including, but not limited to, piezoelectric pumping.
While the invention has been described in detail with reference to exemplary embodiments thereof, it will be apparent to one skilled in the art that various changes can be made, and equivalents employed, without departing from the scope of the invention. The foregoing description of the preferred embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. The embodiments were chosen and described in order to explain the principles of the invention and its practical application to enable one skilled in the art to utilize the invention in various embodiments as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto, and their equivalents. The entirety of each of the aforementioned documents is incorporated by reference herein.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2019/059715 | 11/12/2019 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62760256 | Nov 2018 | US |
