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Publication Number
US-11998883-B2
Publication Date
2024-06-04
Expiration Date
Abstract
This disclosure relates to a magnetic mixing apparatus that mixes a sample contained in a mixing chamber using a stir bar, while minimizing the amount of contact between the stir bar and walls of the mixing chamber. In one aspect, the apparatus comprises a ferromagnetic stir bar contained in the mixing chamber, and a driving magnet and a driven magnet located on opposite sides of the mixing chamber. The driving magnet, the driven magnet, and the ferromagnetic stir bar are each capable of rotating about a respective axis. The driving magnet, the driven magnet, and the ferromagnetic stir bar are magnetically coupled such that rotation of the driving magnet induces rotation of the driven magnet and rotation of the driving magnet and the driven magnet induce rotation of the ferromagnetic stir bar. In some embodiments, rotation of the ferromagnetic stir bar within the mixing chamber mixes the sample contained within the mixing chamber.
Core Innovation
The disclosure describes a magnetic mixing apparatus and associated methods for lysing a cell in a fluid sample and for mixing a fluid sample containing a cell. A driving magnet system and a driven magnet system are magnetically coupled across a gap such that a rotating driven magnet system causes rotation of a stir bar located within a mixing chamber. The stir bar is magnetically coupled between the driving magnet system and the driven magnet system while the mixing chamber is within the gap.
The mixing assembly includes a sample loading well that is in communication with the mixing chamber and supports advancing a sample into the mixing chamber using pneumatic pressure. After mixing or lysing, the sample advances through a filter channel of the mixing chamber into a sample exit channel of the mixing assembly. The method continues rotating the stir bar to produce a lysed sample by mixing the fluid sample within the mixing chamber, and then stops the rotating by de-energizing the drive motor of the driving magnet system.
The disclosure further describes operational constraints and optional features directed to reducing stir-bar contact with chamber bounding surfaces. It specifies alignment of the stir bar rotational axis and the driving and driven magnetic rotational axes and specifies a magnetic gap between the driving magnetic system and the driven magnetic system. It also includes optional field focusers to increase magnetic torque and optional decoupling detection using a microphone or an accelerometer, including stopping the stir bar rotation based on decoupling detection.
Claims Coverage
The provided material includes two independent claims: a lysis method and a mixing method. Together, the independent claims define core inventive features comprising pneumatic sample advancement into a mixing chamber, magnetically driven rotation of a stir bar across a gap using driving and driven magnet systems, and post-mixing movement of fluid through a filter channel to a sample exit channel.
Pneumatic sample advancement into a mixing chamber via a sample loading well
Loading the fluid sample into a sample loading well of a mixing assembly and applying pneumatic pressure to advance the fluid sample into a mixing chamber, including communication between the sample loading well and the mixing chamber.
Magnetically coupled driving and driven magnet systems across a gap
Energizing and rotating a driving magnetic system while the mixing chamber is within a gap between the driving magnetic system and the driven magnetic system, wherein the driven magnet system is magnetically coupled to the driving magnet system.
Magnetically coupled rotation of a stir bar located in the mixing chamber
Rotating a driven magnet system magnetically coupled to the driving magnet system to rotate a stir bar located within the mixing chamber, wherein the stir bar is magnetically coupled between the driving magnetic system and the driven magnetic system.
Lysis production by continuing stir-bar rotation and stopping by de-energizing
Producing a lysed sample by continuing the rotating of the stir bar to mix the fluid sample within the mixing chamber in the lysis claim, and stopping the rotating of the stir bar by de-energizing the drive motor of the driving magnet system.
Filter-channel advancement to a sample exit channel
Advancing the lysed sample or mixed fluid through a filter channel of the mixing chamber into a sample exit channel of the mixing assembly using pneumatic pressure after the mixing or lysis step.
Mixing method without lysing and with stopping and pneumatic advancement
In the mixing claim, mixing the fluid sample within the mixing chamber by rotating a stir bar magnetically coupled between the driving and driven magnetic systems, stopping the rotating step, and applying pneumatic pressure to advance the fluid through a filter channel to a sample exit channel.
The independent claims cover pneumatic loading into a mixing chamber, magnetically coupled driving and driven magnet systems positioned across a gap, stir-bar rotation magnetically coupled between the magnet systems, and pneumatic advancement of mixed or lysed fluid through a filter channel to a sample exit channel, with lysis production defined by continued stir-bar rotation in the lysis claim.
Stated Advantages
Minimizing stir-bar contact with chamber bounding surfaces.
Comparable DNA detection/lysis performance vs bench mixing, as supported by the disclosure experiments.
Documented Applications
RT-qPCR detection from a lysate of Candida albicans produced using the described mixing and lysis approach, with qPCR amplification curves and Cq values used to show comparable performance vs bench mixing.
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