Patent Application
20250144583
The present disclosure relates generally to laboratory mixing devices, and more particularly to magnetic stirring bars used in conjunction with magnetic stirring plates. Specifically, the present disclosure relates to a magnetic stir bar design that expands the range of fluid viscosity suitable for effective mixing. This design enhances liquid turnover rate within the vessel and provides controlled directional flow movement.
A magnetic stir bar is a common device for laboratory-scale mixing, widely utilized in the field of pharmaceutical, biochemical, chemical and polymer industries. The magnetic stir bar is a method of mixing that operates within a closed system, reducing the risk of contamination and maintaining sterility. Compared to mechanical stirring, the absence of an impeller shaft enhances safety and ease of use. The magnetic stir bar operates by coupling to the driver magnet of the magnetic stirrer, and when the motor rotates, it causes the magnetic stir bar to spin accordingly. Typical rotational speed ranges from 60-1200 RPM in clockwise, counterclockwise, or bi-directional rotation.
The magnetic stir bar typically includes an elongated magnet enclosed in a chemical-resistant material such as PTFE or borosilicate glass. Commonly, magnetic stir bars are rod or bar-shaped, with a circular or a polygonal cross-section. These magnetic stir bars are designed to create fluid dynamics similar to a flat-paddle impeller. The magnetic stir bars' shape is commonly slightly altered to fit vessel's shape or to enhance specific mixing tasks, such as promoting movement of solid particles, with variation such as a triangular shape.
Conventional magnetic stir bars encounter challenges when handling high viscosity mixing, suspensions, and emulsions. In high viscosity mixing, the fluid exhibits high resistance to flow, resulting in a low turnover rate and stagnant regions. The turnover rate is an essential variable in assessing the effectiveness of magnetic stir bars in mixing. The turnover rate refers to the frequency at which the total volume of the fluid is mixed or “turned over” by the action of the magnetic stir bar. Moreover, if the resistance to flow overpowers the coupling force between the magnetic stir bar to the driver magnet, decoupling occurs, causing the magnetic stir bar to stop rotating. Increasing the magnetic field strength by using a stronger magnet is an option; however, the rod-shaped magnetic stir bar generates a sub-optimal flow pattern for high viscosity fluids, limiting the effectiveness of this approach.
In emulsion applications, conventional magnetic stir bars fail to produce high-quality emulsions characterized by small, homogeneously distributed droplet sizes due to their low shear force design. One approach to achieve smaller droplet sizes is to increase the shear rate by increasing the RPM. However, this also generates a singular vortex, leading to unwanted air entrapment.
Thick suspensions pose a similar problem, where particulate matter can obstruct the magnetic stir bar, disrupting its motion and leading to inefficient mixing. The solid particles in the suspension tend to settle at the bottom of the container, and the viscosity of the suspension can change over time with variations in the solids content, complicating the achievement of a uniform suspension. Conventional rod-like magnetic stir bars generate radial flow with a low turnover rate, as the fluid is pushed by the two ends of the magnetic stir bar towards the container's edges. Upon colliding with the walls, the fluid loses momentum before rising to a higher liquid elevation, thereby prolonging the time needed to achieve an even distribution. Furthermore, these magnetic stir bars typically produce a singular vortex, which is ineffective for mixing because most of the flow within the vortex does not intermix. This results in poor mixing efficiency, as the fluid primarily circulates within the vortex without adequately blending with the surrounding fluid.
The present disclosure addresses a fundamental challenge in laboratory magnetic mixing process: the limitations of current “one-size-fits-all” magnetic stir bar designs. While convenient, these universal “rod-like” designs often provide inadequate mixing across the diverse range of applications, fluid viscosity range, and experimental requirements encountered in lab-scale research. This disclosure introduces a magnetic stir bar that broadens the effective mixing range, aiming to create a more versatile “one-size-fits-most” solution. By incorporating the concept of handedness in conjunction with the rotational direction of the magnetic stir driver, this design allows for controlled directional flow—either upward or downward. The introduction of axial flow, complementing the traditional radial flow, increases turnover rates and improves flow paths across a wider spectrum of fluid properties. This innovation seeks to enhance mixing efficiency, reduce unwanted air introduction, and improve overall experimental outcomes without necessitating multiple specialized magnetic stir bar designs for different applications. The goal is to provide researchers and professionals with a single, more adaptable tool that can effectively handle a broader range of mixing tasks, thereby increasing efficiency and reducing the need for application-specific magnetic stir bar configurations.
To determine and optimize performance of product design, CFD simulation provides a wealth of information, particularly crucial parameters in fluid dynamics. Pumping capacity in fluid dynamics refers to the amount of liquid leaving the rotating domain of the magnetic stir bar within a specific time frame under defined conditions. In fluid dynamics, the shear rate is defined as a velocity gradient perpendicular to the direction of flow, which means the quantification of how adjacent layers of fluid move or deform relative to each other. It is a measure of the deformation of the fluid due to applied forces. The shear rate is calculated as the velocity gradient perpendicular to the direction of flow, representing the change in velocity between fluid layers. Vorticity is a vector quantity in fluid dynamics that represents the local spinning motion of the fluid at a point, effectively measuring the tendency of fluid elements to rotate around an axis. High vorticity regions indicate strong rotational motion.
Conventional magnetic stir bars typically include a rod-shaped body encapsulating a magnet or a group of magnets. The magnetic poles are generally parallel to the horizontal plane of the driver magnet to stabilize rotational movement. Various derivative shapes have been designed for specific applications, including: oval-shaped rods for round-bottom flasks, triangular-section shapes for mixing suspensions, and cross shapes for vortex mixing in dissolution processes. Several patents have addressed specific aspects of magnetic stir bar design:
U.S. Pat. No. 2,518,758, issued to G. B. Cook in 1950, disclosed an elongated rod-shaped magnetic stirring apparatus with an oval curvature, suitable for use in curved vessels or round-bottom flasks. U.S. Pat. No. 2,951,689, issued to G. B. Cook in 1960, further refined the curved magnetic stir bar design.
U.S. Pat. No. 3,245,665, issued to J. Y. Steel in 1966, disclosed a magnetic stir bar with two bar magnets positioned within an encapsulating body, designed to overcome magnet synchronization issues regardless of the rotation speed of the driver magnet.
U.S. Pat. No. 3,554,497, issued to M. Zipperer in 1971, disclosed a magnetic stir bar with blades on the surface parallel to the magnetic stir driver's rotational axis to intensify the stirring.
U.S. Pat. No. 7,748,893, issued to Yaniv et al. in 2010, disclosed a magnetic stir bar with an entrance and a discharge port to facilitate fluid movement for partial mixing within the vessel, especially designed to mix liquid gels.
U.S. Pat. App. Pub. No. 2017/0007972 A1, by Tien et al., published in 2016, disclosed a magnetic stir bar having protruding blades and a rounded center enclosing a ring or disc magnet, designed to strengthen the coupling force to driver magnet.
The present disclosure relates to a magnetic stir bar designed to overcome the limitations of conventional magnetic stir bars while maintaining compatibility with standard magnetic stir plates. This design aims to expand the capabilities of magnetic stirring by controlling and optimizing flow patterns within the liquid.
Conventional magnetic stir bars, typically rod-shaped, have long been utilized in laboratory and industrial settings for mixing solutions. These devices operate by generating shear forces during rotation, creating high shear areas at the rod's ends and inducing radial flow through centrifugal effects. While this design has proven effective for low viscosity solutions, it exhibits several limitations that impact its efficiency and applicability across diverse fluid conditions.
In low viscosity environments, conventional magnetic stir bars perform adequately, facilitating chemical reactions and mixing processes. However, as fluid viscosity increases, particularly above 500 centipoises (cP), the effectiveness of these devices diminishes significantly. This reduction in efficiency is primarily due to the inherent properties of high viscosity fluids. In such fluids, viscous forces dominate over inertial forces, resulting in a tendency for the fluid to remain stationary or quickly return to its original position after disturbance. Consequently, the radial flow generated by conventional magnetic stir bars fails to induce significant movement in the bulk of the fluid, leading to inadequate turnover rates and incomplete mixing.
Furthermore, the performance of conventional magnetic stir bars is compromised in larger volumes, typically exceeding 1,000 milliliters (mL). During operation, these magnetic stir bars generate shear forces upon rotation, producing two primary effects: a) localized high shear areas at the rod extremities, facilitating efficient mixing in the immediate vicinity, and b) radial flow induced by centrifugal effects, which theoretically promotes liquid turnover within the container. In volumes exceeding 1,000 mL, the radial flow generated by the magnetic stir bar often fails to effectively penetrate the entire fluid volume, resulting in non-uniform mixing throughout the container. This reduction in mixing efficiency can be attributed to the limited sphere of influence of the magnetic stir bar relative to the total fluid volume. As the distance from the magnetic stir bar increases, the energy imparted to the fluid dissipates rapidly, leading to substantially diminished fluid motion in regions distal to the magnetic stir bar, particularly in upper layers of the liquid. Consequently, this phenomenon results in inadequate turnover rates and incomplete mixing in larger volume applications.
A notable drawback of the conventional design is the propensity for vortex formation at rotational speeds exceeding 600 revolutions per minute (RPM). This vortex effect, caused by the combination of radial flow and centrifugal forces, can significantly reduce mixing efficiency and inadvertently introduce unwanted air or gas into the solution, potentially altering the chemical or physical properties of the mixture.
A persistent limitation of conventional rod-shaped magnetic stir bars is the occurrence of magnetic decoupling. The torque required for mixing scales with fluid viscosity, rotational speed, and the square of the magnetic stir bar's characteristic length. As rotational speed increases in low viscosity fluids, the drag force on the magnetic stir bar can exceed the magnetic coupling force, leading to decoupling. This phenomenon also occurs in high viscosity fluids, where the increased viscous forces necessitate a higher torque. When the combined effects of viscous and drag forces surpass the maximum available magnetic coupling torque, decoupling ensues, interrupting the mixing process and often requiring manual intervention. While increasing the magnetic field strength could theoretically address decoupling, such an approach fails to address the fundamental deficiency: the rod-shaped geometry generates sub-optimal flow patterns across various fluid conditions.
One aspect of the present disclosure includes a magnetic stir bar with a core made with non-reactive material integrated with one or multiple oriented blades. The oriented blades are configured to propel fluid in a predetermined direction, creating a mixed-flow movement, while the core shape is engineered to further direct and optimize fluid flow. The core encapsulates at least one magnet configured to couple with the driver magnet of a magnetic stir plate.
Another aspect of the present disclosure pertains to the oriented blades integral to the core. The angle and number of blades are optimized through Computational Fluid Dynamics (CFD) analysis. The handedness of the oriented blades, in conjunction with the rotation direction of the magnetic stir bar, generates a mixed-flow path with an axial component directing flow either upward or downward when the magnetic stir bar rotates.
In one aspect of the present disclosure, the oriented blades induce upward liquid motion. The aspect operates by drawing fluid from a lower region (hereinafter referred to as head) and expelling it at an upper region (hereinafter referred to as tail). This fluid motion is particularly beneficial in fluids with viscosity exceeding 500 cP, where turnover rate is essential to mixing efficiency. This aspect facilitates principles of positive displacement: the orientated blades are arranged to create an interconnected pathway to guide the fluid along a predetermined diagonal trajectory, inclined at an angle. This design leverages the concept of boundary layer adhesion and controlled fluid entrainment. Rotation of the blades generates a thin layer of fluid that adheres to the blades' surface. The angled orientation of the blades then directs the fluid layer upward, entraining adjacent fluid volumes in the process. This mechanism establishes a continuous upward flow, effectively countering the tendency of high-viscosity fluids to remain stationary or quickly return to their original position after disturbance.
In another aspect of the present disclosure, the oriented blades induce downward liquid motion, drawing fluid from the upper region (tail) and expelling it at the lower region (head). This configuration demonstrates particular efficacy in heterogeneous phase mixing scenarios, such as organic-to-aqueous phase (emulsion) or liquid-to-solid phase (suspension) systems. The present disclosure leverages principles of controlled fluid displacement and directional flow to achieve its mixing effect. As the magnetic stir bar rotates, the configured angled orientation of the blades generates a downward-directed fluid velocity, guiding the liquid directly to the bottom of the vessel. This mechanism facilitates enhanced dispersion of solids within the liquid phase in suspension systems. In emulsion applications, the downward pumping motion rapidly incorporates the organic phase at lower rotational speeds, initiating efficient mixing of the two phases while mitigating the formation of a singular vortex typically caused by the radial centrifugal force of spinning conventional magnetic stir bars.
A further aspect of the present disclosure pertains to a specialized configuration of the oriented blades optimized for downward pumping in high-shear applications. This configuration is particularly advantageous in emulsion systems where reduction of the organic phase into smaller droplet sizes is desirable. This aspect of the present disclosure utilizes high shear blade design to achieve its effect. As the magnetic stir bar rotates, the oriented blade geometry generates localized regions of high shear stress within the fluid.
Another aspect of the disclosure concerns the configuration and arrangement of the magnetic stir bar, including the core shape, magnet placement, and the curvature of the head and tail. When used in conjunction with an appropriate vessel geometry, these features enable the magnetic stir bar to maintain a tilted spinning axis relative to the stir plate's spinning axis during operation.
The head of the magnetic stir bar is configured with a specific curvature that ensures a single stable position. This design facilitates unique kinematic behaviors, notably precession. In the context of the present disclosure, precession refers to a comparatively slow rotation of the magnetic stir bar's main spinning axis of rotation around a secondary vertical axis. This precession movement generates substantial agitation of the liquid within the vessel without forming a singular vortex, thereby improving mixing efficiency while reducing unwanted effects such as air entrapment.
In one aspect of the present disclosure, the curvature of the head is engineered to allow the magnetic stir bar to maintain a stable tilted axis during operation. In an operation where multiple vessels are places on a single magnetic stir plate, this tilted-axis configuration offers an advantage to enable multiple magnetic stir bars of identical design to exhibit consistent rotational behavior when placed within the effective range of a single driver magnet. Consequently, this feature facilitates uniform and simultaneous mixing across multiple vessels positioned on the same magnetic stirring plate.
The behavior of a given aspect during its usage is highly influenced by the position of its center of mass. First, at the beginning of a mixing process, an adapted position of its center of mass may assist the aspect to successfully couple with the stir plate. Furthermore, when this center of mass is low enough and placed on its rotational axis, this configuration is known as balanced and may allow the aspect to reach a wide range of rotational speed. To arrange the position of the center of mass, an aspect may incorporate to one or a plurality of ballast, nested within.
Disclosed herein is a magnetic stir bar configured for use with a magnetic stir plate, the magnetic stir bar including: a core, a head section interconnected to the core, a tail section interconnected to the core, and a configuration of the core extending from the head section to the tail section. The core includes at least one magnet to couple with a driver magnet of the magnetic stir plate, wherein the core also may include a ballast, wherein the ballast is made of a ferromagnetic material that does not interfere with the magnetic stir bar's magnetic coupling to the driver magnet during operation; at least one oriented blade integrally formed with the core, wherein the at least one oriented blade is configured to propel a liquid in a liquid pumping direction during the rotation of the magnetic stir bar; wherein the orientation of the at least one oriented blade is either left-handed, right-handed, or straight (with some aspects of the present disclosure only having a left-handed orientation or a right-handed orientation); wherein the orientation of the at least one oriented blade, in combination with the rotational direction of the magnetic stir bar, determines the liquid pumping direction upward or downward relative to the magnetic stir plate; wherein the at least one oriented blade is modifiable to accommodate specific vessel shapes; wherein the at least one oriented blade may have variable pitches along its length; and wherein if there are two or more oriented blades, each of the two or more oriented blades have a variable pitch that is independently configurable. The head section interconnected to the core includes a contact area to the vessel, a rotational axis, wherein the magnetic stir bar may spin on the same axis as or on a tilted axis to a stirring axis of the magnetic stir plate; wherein when the rotational axis is tilted relative to the stirring axis of the magnetic stir plate, the magnetic stir bar exhibits a secondary dual-axis motion characterized as a precession motion; in an upward pumping mode, the head section serves as entrance for the liquid; and in a downward pumping mode, the head guides the liquid discharge to a predetermined direction. The tail section interconnected to the core includes: in the upward pumping mode, the tail section guides the liquid discharge to a predetermined direction, and in the downward pumping mode, the tail section serves as entrance for the liquid. The configuration of the core extending from the head section to the tail section serves as a secondary flow guide to direct the liquid to be discharged in a specific mixed flow pattern; and two or more vessels may be stirred using one of the magnetic stir bars in each vessel, wherein the two or more vessels are on the same magnetic stir plate at the same time. The magnetic stir bar may also be a magnetic impeller. Additionally, in applications where multiple magnetic stir bars are used on the same magnetic stir plate simultaneously, the rotation of each magnetic stir bar does not interfere with the rotation of other magnetic stir bars in the adjacent vessels, allowing for simultaneous, consistent, and multi-vessel stirring across multiple vessels positioned on the same magnetic stir plate.
Disclosed herein also is a method of using a magnetic stir bar, the method including the steps of: providing a plurality of vessels, each containing a magnetic stir bar configured to rotate about a rotational axis, wherein the magnetic stir bar may spin on the same axis as, or on a tilted axis to, a stirring axis of the magnetic stir plate; positioning the vessels containing the magnetic stir bars on a single magnetic stir plate, wherein the vessels are arranged within the operational range of a driver magnet contained within the magnetic stir plate; powering on the magnetic stir plate to rotate the driver magnet, thereby inducing a uniform rotation behavior of the magnetic stir bar in their respective vessels within the entirety of effective area of the driver magnet; and generating a mixed-flow pattern within each vessel across the magnetic stir plate, wherein the rotation of each magnetic stir bar does not interfere with the rotation of other magnetic stir bars in the adjacent vessels, allowing for simultaneous, consistent, and multi-vessel stirring across multiple vessels positioned on the same magnetic stir plate. The magnetic stir bar disclosed herein may be used to carry out this method.
The scope of the present disclosure encompasses any and all combinations of the configurations and aspects described herein, provided that the features included in any such combination are not mutually exclusive or incompatible, as would be understood by a person of ordinary skill in the art based on the context, specification, and common knowledge in the field. The present disclosure is not limited to the specific aspects disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the present disclosure. Additional advantages, aspects, and features of the present disclosure will become apparent from the following detailed description, when considered in conjunction with the accompanying drawings and claims.
Referring now to the drawings, and more particularly to
One aspect of the present disclosure discloses a magnetic stir bar design including four features, each feature contributing to enhanced mixing capabilities. The first feature is one or more oriented blades 120a, which serve as the primary fluid dynamic elements. These blades 120a are configured to generate and direct fluid flow during operation. The second feature is a core 110a, which serves a dual purpose: it provides a housing for the magnet(s) 130a, ensuring its placement and orientation, and functions as a flow director, working in tandem with the oriented blades 120a to guide the generated fluid flow along predetermined pathways. The third feature includes one or more magnets 130a, for operational coupling with an external driver magnet 311. This magnetic element facilitates the transfer of rotational motion from a magnetic stir plate to the magnetic stir bar. The fourth feature is a ballast 140a, which, when incorporated into the design, serves to improve the operational stability of the magnetic stir bar 101a. This ballast allows for fine-tuning of the device's center of mass, enabling smooth and consistent rotation.
The core 110a feature is configured to minimize resistance to liquid flow while providing sufficient volume for housing the magnets 130a. This configuration ensures the structural integrity of the magnetic stir bar and facilitates the recovery of the magnetic stir bar after use. The core 110a may also be contoured to guide liquid propelled by the blades 120a in a specific direction, enhancing flow pattern precision. The head 111a of the core 110a is in constant contact with the vessel, influencing its position and movement during operation. The opposite end of the head 111a is the tail 112a. The shape of the head 111a is circular to allow a smooth rotational movement. In one aspect of the present disclosure, the dimensions of the core 110a range from about 2 mm to about 500 mm. In another aspect of the present disclosure, the dimensions of the core 110a range of about 5 mm to about 150 mm.
Another aspect of the present disclosure pertains to a magnet 130a for coupling with external driver magnets to enable controlled rotational motion. This aspect incorporates at least one magnet 130a, securely housed within respective inner cavities 113a in the core 110a. The magnetic orientations of these magnets 130a can be varied to achieve specific, predetermined movement patterns of the magnetic stir bar 101a. The magnets 130a are designed with optimized shapes and dimensions to be integrated within the core 110a to ensure reliable movement of the magnetic stir bar 101a, and cost-effective manufacturing. The shapes of the magnets 130a encompassed by this aspect of the present disclosure include, but are not limited to, cubes, cuboids, cylinders, triangular prisms, hexagonal prisms, and parallelepipeds, allowing for flexibility in design and performance optimization. In one aspect of the present disclosure, the dimensions of these magnets 130a range from about 0.5 mm to about 100 mm. In another aspect of the present disclosure, the dimensions of these magnets 130a range from about 1.5 mm to about 20 mm.
In one aspect of the present disclosure, the overall shape of the magnetic stir bar 101a is designed to enable introduction and recovery into and from the targeted vessel 301. In using a magnetic stir bar retriever, a conventional tool for recovering magnetic stir bars, the magnetic stir bar shape, weight and magnet 130a placement have to be adapted. A ballast 140a can be integrated into the design to participate in the movement stability. In one aspect of the present disclosure, the overall shape height dimensions of the magnetic stir bar 101a are between about 0.5 mm and about 500 mm. In yet another aspect of the present disclosure, the overall shape height dimensions of the magnetic stir bar 101a are between about 1 mm and about 250 mm. In one aspect of the present disclosure, the overall shape diameter dimensions of the magnetic stir bar 101a are between about 0.5 mm and about 600 mm. In yet another aspect of the present disclosure, the overall shape diameter dimensions of the magnetic stir bar 101a are between about 1 mm and about 300 mm.
One aspect of the present disclosure discloses that the arrangement of the magnetic stir bar 101a and the magnet cavity 113a placement are engineered to promote a single, stable movement pattern during operation. The center of mass of the magnetic stir bar 101a is positioned to maintain stability at higher rotational speeds. This aspect of the present disclosure employs two primary strategies to achieve this stable movement: a self-standing strategy and a lay-down strategy. The self-standing strategy, as shown in
The present disclosure further encompasses permutations of key elements of the magnetic stir bar arrangement to optimize performance for specific applications, as illustrated in
In one aspect of the present disclosure, the pitch of the oriented blade 120a is the distance along an axis that runs through the center of the core 110a from the head 111a to the tail 112a which the oriented blade 120a travels after one full rotation either clockwise or counterclockwise around the core 110a. In another aspect of the present disclosure, the pitch of the oriented blades 120i, 120ii, 120iii, 120iv, and 120v is the distance along an axis that runs through the center of the cores 11Θ0, 110ii, 110iii, 110iv, and 110v respectively from the heads 111i, 111ii, 111iii, 111iv, and 111v respectively to the tail 112i, 112ii, 112iii, 112iv, and 112v respectively which the oriented blades 120i, 120ii, 120iii, 120iv, and 120v travel after one full rotation either clockwise or counterclockwise around the cores 11Θ0, 110ii, 110iii, 110iv, and 110v respectively. In one aspect of the present disclosure, the pitch of the oriented blade 120a may be constant or variable along the length of the oriented blade 120a. In another aspect of the present disclosure, the pitch of oriented blades 120i, 120ii, 120iii, 120iv, and 120v may be constant or variable along the length of oriented blades 120i, 120ii, 120iii, 120iv, and 120v respectively.
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Referring to
In one aspect of the present disclosure, the angle between the stirring axis (S) 420 and the rotational axis (P) 430 is between about 0° to about 90°. In another aspect of the present disclosure, the angle between the stirring axis (S) 420 and the rotational axis (P) 430 is between about 0° to about 25°. In yet another aspect of the present disclosure, the angle between the stirring axis (S) 420 and the rotational axis (P) 430 is between about 22° to about 65°. In yet another aspect of the present disclosure, the angle between the stirring axis (S) 420 and the rotational axis (P) 430 is between about and between about 40° to about 90°. It is noted that in standard laboratory practice, stirring axis (S) 420 is predominantly oriented vertically with respect to the supporting surface. This vertical orientation of stirring axis (S) 420 serves as a reference point for describing the relative orientation of the rotational axis (P) 430 in this aspect of the present disclosure. The ability to manipulate the relative orientation of the stirring axis (S) 420 and the rotational axis (P) 430 enables control over fluid dynamics and mixing efficiency.
In one aspect of the present disclosure, in reference to
In one aspect of the present disclosure, which utilizes the self-standing strategy, referring now to
In another aspect of the present disclosure which utilizes the lay-down strategy, referring now to
In yet another aspect of the present disclosure which utilize the lay-down strategy in narrow vessel, referring now to
One aspect of the present disclosure is characterized by a distinct handedness, which defines the directional orientation of the blades 120a as they wind around the core 110a. In this aspect of the present disclosure, the magnetic stir bar 101a is configured in either a right-handed configuration 501 or a left-handed configuration 502. In the right-handed configuration 501, the blades 120a follow a helical path such that, when viewed axially from either end of the core 110a, the blades 120a wind in a clockwise direction as they progress along the length of the core 110a. Conversely, in the left-handed configuration 502, the blades 120a wind in a counterclockwise direction when viewed axially from either end of the core 110a. To further elucidate, in the right-handed configuration 501, if an observer were to grasp the axis of the core 110a with their right hand such that their thumb points towards the tail 112a, their fingers would curl in the same direction as the helical path of the blades 120a. The left-handed configuration 502 is the mirror image of the right-handed configuration 501.
In the operation of one aspect of the present disclosure, two distinct fluid flow patterns contingent upon the handedness of the device and the rotational direction of the driver magnet are generated. These patterns are characterized as up-pumping and down-pumping flows.
In one aspect of the present disclosure which exhibits a right-handed configuration 501, the following fluid dynamics are observed. a) When coupled with a clockwise-rotating driver magnet 311, this aspect of the present disclosure induces a fluid flow directed upward in a conical path, guided by the inclined surfaces of the blades 120a. b) Conversely, when coupled with a counterclockwise-rotating driver magnet 311, the same device induces a conical fluid flow directed downward, utilizing the same inclined surfaces of the blades 120a.
In another aspect of the present disclosure which exhibits a left-handed configuration 502, the fluid dynamics are inverted. a) Coupling with a counterclockwise-rotating driver magnet 311 results in a conical upward fluid flow. b) Coupling with a clockwise-rotating driver magnet 311 produces a conical downward fluid flow.
In one aspect of the present disclosure, the oriented blades include one or more blades 120i, ranging in number from one to twelve, with their specific arrangement, quantity, profiles, and dimensions strategically designed to accommodate a predetermined range of operational parameters. These parameters include, but are not limited to, rotational speed range, fluid viscosity range, desired overall flow pattern, and specific vessel geometry. The characteristics of the fluid and the desired mixing pattern are then computed and optimized via CFD. This analysis leads to a functional division of the blade profiles into three distinct zones: 1) intake zone 621i, 2) transport zone 622i, and 3) discharge zone 623i. Referring to the
In another aspect of the present disclosure, with respect to
In yet another aspect of the present disclosure, with respect to
In another aspect of the present disclosure, the liquid path is the volume defined by the rotating domain subtracted of the body of the core 110i and the bodies of the blades 120i.
In one aspect of the present disclosure, the intake zone 621i is characterized by an expansion of the liquid path cross-section along the core 11Θ0, generating a low-pressure region that induces liquid flow into the magnetic stir bar 101i. The transport zone 622i is characterized by a relatively constant liquid path cross-section, with the purpose of forcibly moving the liquid axially along the magnetic stir bar 101i. This transport zone 622i facilitates vertical displacement of the fluid, ensuring that fluid from different layers is continuously intermixed. The discharge zone 623i is characterized by a reduction of the liquid path cross-section, with the purpose of discharging the liquid in a predetermined direction.
In one aspect of the present disclosure, a bi-directional configuration is characterized by its capacity to generate an overall flow going either in an upward or downward direction, depending on its spinning direction. In this configuration, the intake zone 621i, responsible for drawing in the fluid, can be positioned at either the top or bottom of the magnetic stir bar 101i. The fluid subsequently flows through the transport zone 622i in the midsection, where it undergoes axial layer transport and acceleration induced by the rotating magnetic stir bar. Finally, the fluid exits through the discharge zone 623i situated at the opposite end of the device where it undergoes directional manipulation. A mono-directional configuration is characterized by a design optimized for one working direction, typically from top to bottom.
Referring to
Within the cylindrical coordinate system, any point M is defined by three parameters. The radial coordinate (r), representing the perpendicular distance from point M to the rotational axis (P) 430. The angular coordinate (0), defined in the plane perpendicular to the rotational axis (P) 430 between the polar axis (A) 1330 and the projection of the point M's position vector. The axial coordinate (h), defined by the distance traveled along the rotational axis (P) 430 from the origin to the projection of point M.
Each blade of the stir bar includes a band of material characterized by a specified length and thickness. The anchor of the blade on the surface of the core is the blade root, further designated as point M′ 1341. The free blade edge, extending from the blade root, further designated as point M″ 1343. The positions of M′ 1341 and M″ 1343 are described by the following mathematical system of equations:
For any point M′ of a blade's edge or M″ from a root's curve, its coordinates follow
These equation systems contain three equations, wherein r′ and r″ represents the radial distance of the points M′ and M″ from the rotational axis (P) 430 in millimeters (mm), θ′ and θ″ represents the angular coordinate of the points M′ and M″ to the polar axis (A) 1330 in degrees (°), h represents the height of the point M′ and M″ along the rotational axis (P) 430 in millimeters (mm), and R2′, R1′, R0′, Θ2′, Θ1′, Θ0′ and R2″, R1″, R0″, Θ2″, Θ1″, Θ0″all represent constants determined by the given aspect's specifications.
In one aspect of the present disclosure, the values of the constants in equations (1′) and (1″) may fall within the following ranges: R2′ and R2″ may fall within the range of about −150 mm−1 and about 150 mm−1, R1′ and R1″ may fall within the range of about −300 and about 300, and R0′ and R0″ may fall within the range of about Omm and about 1000 mm. In another aspect of the present disclosure, the values of the constants in equations (1′) and (1″) may fall within the following ranges: R2′ and R2″ may fall within the range about −90 mm−1 and about 90 mm−1, R1′ and R1″ may fall within the range of about −120 and about 120, and R0′ and R0″ may fall within the range of about 0.5 mm and about 500 mm.
In one aspect of the present disclosure, the values of the constants in equations (2′) and (2″) may fall within the following ranges: Θ2′ and Θ2″ may fall within the range of about −160°·mm−2 and about 160°·mm−2, Θ1′ and Θ1″ may fall within the range of about −180°·mm−1 and about 180°·mm−1, and Θ0′ and Θ0″ may fall within the range of about 0° and about 360°. In another aspect of the present disclosure, the values of the constants in equations (2′) and (2″) may fall within the following ranges: Θ2′ and Θ2″ may fall within the range of about −100°·mm2 and about 100°·mm−2, Θ1′ and Θ1″ may fall within the range of about −95°·mm−1 and about 95°·mm−1, and Θ0′ and Θ0″ may fall within the range of about 0° and about 360°.
In one aspect of the present disclosure, the value of the variables in equations (3′) and (3″) may fall within the following range: the maximum height of both root and edge curves, h′ and h″, fall within the range of about 0.5 mm to about 300 mm. In another aspect of the present disclosure, the maximum value of the variable h′ and h″falls within the range of about 1 mm to about 200 mm.
In one aspect of the present disclosure, the intake zone 621iii, the transport zone 622iii and the discharge zone 623iii from
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In another aspect of the present disclosure, referring to
In yet another aspect of the present disclosure, referring to
In one aspect of the present disclosure, with respect to
In one aspect of the present disclosure, the helix angles (h°) 710iii of the edge of its oriented blade 120iii may exhibit an either fixed or variable profile, configured to fall within the ranges of about 10° to about 89° or about −10° to about −89°. In another aspect of the present disclosure, the helix angles (h°) 710iii of the edge of its oriented blade 120iii fall within the ranges of about 15° to about 88° or about −15° to about −88°.
Referring to the
Referring to the
Referring to the
The flow movement of a few aspects of the present disclosure have been analyzed using CFD, a specialized area of fluid mechanics, which utilizes numerical methods and algorithms to analyze and solve fluid flow problems. By leveraging computational resources, CFD simulations provide comprehensive insights into fluid behavior across various conditions, encompassing both laminar and turbulent flows. This technology optimizes design parameters and improves overall performance, making it a useful tool in the development and refinement of fluid-related systems and components.
Referring to
Referring to
The magnetic stir bar 101iii from
Referring to
Referring to
In one aspect of the present disclosure, with respect to
In one aspect of the present disclosure, the cores 110a, 11Θ0, 110ii, 110iii, 110iv, 110v, and 110vi and the blades 120a, 12Θ0, 120ii, 120iii, 120iv, 120v, and 120vi of the magnetic stir bars 101a, 101i, 101ii, 101iii, 101iv, 101v, and 101vi respectively are constructed from solvent-resistant materials to prevent contamination and ensure safety and reliability. Suitable materials for this purpose include, but are not limited to, metals and alloys such as stainless steel and titanium, ceramics such as borosilicate glass and alumina, and engineering-grade polymers. Examples of these polymers include: polytetrafluoroethylene (PTFE), polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyaryletherketone (PAEK), polyetherketone (PEK), polyetherimide (PEI), polyamide (PA), polyacetal (POM), polyphenylene sulfide (PPS), polysulfone (PSU), polyphenylsulfone (PPSU), polypropylene (PP), high-density polyethylene (HDPE), ultra-high molecular weight polyethylene (UHMWPE), cellulose, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polybutylene naphthalate (PBN), and polyphenylene oxide (PPO).
In one aspect of the present disclosure, the magnet material provides sufficient magnetic flux density to meet the torque requirements and ensure reliability. Suitable materials include, but are not limited to, ferrite magnets composed of iron (Fe) oxide and either strontium carbonate (SrCO3) or barium carbonate (BaCO3); AlNiCo magnets, which are alloys of aluminum (Al), nickel (Ni), and cobalt (Co); and rare-earth magnets, which are alloys of neodymium (Nd), iron (Fe), samarium (Sm), and boron (B). In one aspect of the present disclosure, the magnet 130a includes permanent magnets selected from the group consisting of SmCo grades 18-32 and AlNiCo grades 5-9, due to their superior magnetic properties and temperature stability at elevated temperatures. In other aspects of the present disclosure containing multiple magnets, the magnets may be composed of the same or different materials.
In one aspect of the present disclosure, the ballast 140a material possesses specific density and magnetization properties. Suitable materials include ferromagnetic materials such as iron (Fe), various grades of steel, cobalt (Co), iron oxide (Fe2O3), and neodymium-iron-boron alloy (Nd2Fe14B). The ballast can also be made from ceramic materials, including but not limited to ferrite ceramics, silica-based ceramics, alumina (Al2Θ3), zirconia (ZrO2), and various mineral-based ceramics.
In one aspect of the present disclosure, the manufacturing technique for the magnetic stir bar 101a includes core 110a and the oriented blade 120a may include, but is not limited to, injection molding, compression molding, computer numerical control (CNC) machining and additive manufacturing (AM) processes.
The additive manufacturing technique, often referred to as 3D printing, encompasses a variety of manufacturing processes wherein three-dimensional object are fabricated by selectively depositing or solidifying material in a layer-by-layer manner. Common additive manufacturing techniques suitable for fabricating the body 110a and the blade 120a include but are not limited to: a) fused deposition modeling (FDM), b) stereo-lithography (SLA), c) selective laser sintering (SLS), and d) binder jetting processes.
In one aspect of the present disclosure, the fused deposition modeling (FDM) technique is employed for manufacturing the core 110a and the blade 120a. FDM is and additive manufacturing process that precisely deposits thermoplastic material in a layer-by-layer fashion to create the desired three-dimensional object. The manufacturing process includes the following steps:
The following examples are provided to illustrate various aspects of the present disclosure. These examples are intended to be illustrative and not limiting in nature. It should be understood by those skilled in the art that numerous variations, modifications, and alternative aspects are possible without departing from the spirit and scope of the present disclosure as defined by the specification and the claims. The examples described herein are non-exhaustive and serve to demonstrate the versatility and effectiveness of the present disclosure across diverse scenarios and applications. While specific configurations and parameters may be described, it is to be understood that these are exemplary in nature and that the present disclosure is not confined to the precise details set forth in these examples.
Effective dispersion of reagents and additives in a high-viscosity liquid is crucial in industrial applications. The turnover rate serves as a quantitative indicator of how effectively mixing achieves an even distribution. CFD simulations were used to optimize the design; yielding a pumping capacity of 2.64 for aspect ii and 1.68 for a comparative conventional magnetic stir bar in 500 mL vessel.
The experiment to evaluate dispersion efficiency in high-viscosity liquid was to place aspect ii from
From CFD analysis, the pumping capacity of aspect ii is 1.6 times greater than that of the conventional magnetic stir bar. The actual experimental results, shown in Table 1 indicate that aspect ii achieved an average turnover rate of 44.1 turnovers per hour in 200 mL, which is 2.74 times higher than the conventional magnetic stir bar's 16.1 turnovers per hour in the same volume. In 400 mL, aspect ii achieved 23.2 turnovers per hour, which is 2.09 times higher than the conventional magnetic stir bar's 11.1 turnovers per hour. This difference in turnover rate underscores the effectiveness of the design of aspect ii. The screw blade design of aspect ii optimizes flow behavior across a wider range of viscosity compared to the conventional magnetic stir bar. This feature enables efficient and uniform particle dispersion while maintaining higher turnover rates, even in larger volumes with high viscosity liquids. Aspect ii demonstrated enhanced performance in dispersion applications.
Aspect iii from
The experiment to evaluate emulsifying efficiency was to place aspect iii (D=40 mm, H=16 mm) versus a double-ended magnetic stir bar (D=8 mm, L=35 mm) in a 1L vessel (I.D.=108.2 mm) containing 900 g of 0.4% sodium lauryl sulfate (SLS) surfactant and 100 g of soybean oil. The magnetic stirring hot plate utilized was a Corning™ PC-420D to drive the magnetic stir bar. The double-ended magnetic stir bar operated at 400 RPM (the maximum allowable speed for its design) and aspect iii operated at 800 RPM (enabled by its improved high RPM stability) were used to emulsify the oil-water mixture. 2 mL oil droplets were sampled at regular intervals from 0.25, 0.5, 0.75, 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29, and 31 minutes, at a distance of 100 mm from the spinning center and 50 mm below the liquid surface. ImageJ™ software analyzed the size of 300 droplets per sampling; results are presented in Table 2.
After 31 minutes of mixing, aspect iii produced droplets with an average size of 60 μm, while the double-ended magnetic stir bar yielded droplets with an average size of 220 μm. This significant difference in droplet size highlights the impact of shear rate on emulsion quality. Aspect iii's higher shear rate effectively broke down the oil droplets into much smaller sizes, enhancing the emulsion's stability and uniformity. The double-ended magnetic stir bar's lower shear rate resulted in larger, less effective droplets. Aspect iii demonstrates superior efficiency in producing fine emulsions due to its enhanced shear performance compared to conventional stirring devices.
Gold nanoparticles (AuNPs) have found significant commercial applications in catalysis, medical, and electronic industries since 2013. However, the synthesis of AuNPs faces challenges in achieving precise size and shape control, due to the inherent tendency of nanoparticles to agglomerate. Efficient, vigorous mixing is critical for obtaining reproducible results.
This exemplary aspect of the present disclosure compares the mixing efficiency of the present disclosure, aspect v from
The Brust-Schiffrin synthesis method proceeds as follows: hydrogen tetrachloroaurate (III) hydrate (4.0 g, 1 equivalent) was dissolved in ultra-pure deionized (DI) water and stirred at the respective RPM for 5 minutes. A stock solution of tetra-n-octyl ammonium bromide (8.2 g, 1.5 equivalents) was then added drop-wise to the solution while stirring at the respective RPM for 15 minutes. Subsequently, 1-pentanethiol (2.6 g, 2 equivalents) was added drop-wise over 15 minutes. A stock solution of sodium borohydride (8.0 g, 20 equivalents) in ultra-pure DI water was then rapidly added. The resulting solution was stirred for 4 hours, after which the synthesized AuNPs are purified. The size of the synthesized AuNPs was confirmed by transmission electron microscopy (TEM).
The TEM particle analysis, the results of which are shown in
Friedel's salt has gained prominent attention in the adsorption technology for reducing heavy metal contaminants in wastewater, however its synthesis process is challenging. The success of Friedel's salt crystal, Ca2Al(OH)6,(Cl,OH)·2H2O, formation depends on the distribution of the elements in the process of forming stable nuclei of homogeneous size. The presence of hydroxyls after the addition of NaOH into the mixture generate CaAl2(OH)6+ to bond with Cl,OH and H2O producing the two-layer-hydroxide structure, this reduce the solubility of the suspension, making the nuclei to settle to the bottom of the vessel. Inadequate mixing can prevent the nuclei and unreacted elements to form the desired product. Consequently, a portion of the reagent transforms into by product compounds like lime, mayenite, or caustic lime.
To solve this problem, aspect i from
To prove this concept, an experiment is conducted to evaluate the usage efficiency of two different magnetic stir bars in this thick suspension. Involving an oval shaped magnetic stir bar (L=34 mm, D=11 mm) and the present aspect of a magnetic stir bar 101a referred to in
The synthesis method applied is co-precipitation technique, where a 2:1 ratio of calcium chloride (CaCl2) and aluminum chloride (AlCl3) is dissolved in water, followed by the gradual addition of a sodium hydroxide (NaOH) solution under constant stirring to maintain a pH of around 9 to 11.5. The mixture is then aged in the mother solution at 90° C. for 48 hours. The precipitate is subsequently washed, filtered to remove any unreacted reagents, and then dried at 90° C. for 5 hours. The successful synthesis of Friedel's salt was pulverized and sieved with 100 mesh prior to X-ray diffraction (XRD) pattern analysis.
The present disclosure addresses a common challenge in the coatings and adhesives industry, specifically the time-consuming process of polymer dissolution in solution casting applications. Conventional methods typically require 2 to 6 hours for complete dissolution, disrupting workflow. The rate of polymer dissolution is directly related to the frequency of interaction between the polymer and the surrounding solvent. Aspect iv from
The experiment to evaluate dissolution rate was to place aspect iv (L=36 mm, H=11 mm) and a conventional magnetic stir bar (L=25 mm, D=8 mm) in a 250 mL Erlenmeyer flask (maximum D=85 mm) containing 100 g of n-hexane and 0.5 g of NdBR (KIBIPOL™ PR-060). The magnetic stirring hot plate utilized was an IKA™ C-MAG HS 7 to drive the magnetic stir bars. Aspect iv and the conventional magnetic stir bar were operated at 600 RPM and 500 RPM, respectively, to dissolve the NdBR into n-hexane at 60° C. After 100 minutes of mixing, 35 g of the solution was transferred into a sample vial (D=40 mm, H=75 mm) and place on the hot plate to remove the solvent at 85° C. Once all the solvent has evaporated to constant weight, the dissolved polymer weight is the final weight of the vial subtracted from the tare weight of the vial. The weight was measured using a SHIMADZU™ MOC63u with three decimal points of precision, then divided by 100 minutes to determine the rate of dissolution, as shown in Table 3.
The results of the experiment demonstrate an improvement in the dissolution rate with aspect iv. The conventional magnetic stir bar achieved an average dissolution rate of 0.55 mg/min, whereas aspect iv achieved an average dissolution rate of 1.11 mg/min, representing a 101.8% increase in dissolution efficiency. Aspect iv enhances the efficiency of polymer dissolving in solution casting applications by generating a chaotic flow pattern that suppresses vortex formation, enabling operation at higher rotation speeds while minimizing air entrapment. This improvement has practical implications for reducing the time required for polymer dissolution in the coatings and adhesives industry.
The examples described herein are illustrative and non-exhaustive. One of ordinary skill in the art may recognize that numerous further combinations and permutations of the present specifications are possible. Each of the aspects of the present disclosure described above may be in combination in any permutation to define the aspects disclosed herein. Not all elements are necessary in every aspect, and additional elements beyond those described may be included within the scope of the present disclosure. The specification and drawings are to be regarded in an illustrative rather than a restrictive sense.
Clause 1: A magnetic stir bar including: a core, the core having a head and a tail, wherein the head and tail are on opposite ends of the core; a rotational axis, wherein the rotational axis runs along the center of the core, running through the head and the tail; at least one magnet, wherein the at least one magnet is located within the core; and at least one oriented blade connected to the core, wherein the orientation of the at least one oriented blade is either left-handed, right-handed, or straight, wherein the at least one oriented blade has an intake zone, a transport zone, and a discharge zone, wherein the transport zone is situated between the intake zone and the discharge zone; wherein the angle between the intake zone of the at least one oriented blade and the rotational axis is in the range of about 0° to about 900 or about −0° to about −90°; the angle between the transport zone of the at least one oriented blade and the rotational axis is in the range of about 0° to about 90° or about −0° to about −90°; and the angle between the discharge zone of the at least one oriented blade and the rotational axis is in the range of about 0° to about 90° or about −0° to about −90°.
Clause 2: The magnetic stir bar of clause 1, wherein the angle between the intake zone of the at least one oriented blade and the rotational axis is in the range of about 100 to about 700 or about −10° to about −70°; the angle between the transport zone of the at least one oriented blade and the rotational axis is in the range of about 15° to about 80° or about −15° to about −80°; and the angle between the discharge zone of the at least one oriented blade and the rotational axis is in the range of about 200 to about 890 or about −20° to about −89°.
Clause 3: The magnetic stir bar of clause 1, wherein the angle between the intake zone of the at least one oriented blade and the rotational axis is in the range of about 300 to about 600 or about −30° to about −60°; the angle between the transport zone of the at least one oriented blade and the rotational axis is in the range of about 370 to about 650 or about −37° to about −65°; and the angle between the discharge zone of the at least one oriented blade and the rotational axis is in the range of about 450 to about 700 or about −450 to about −70°.
Clause 4: The magnetic stir bar of clause 1, wherein the core further includes a ballast, wherein the ballast is made of a ferromagnetic material that does not interfere with the magnetic stir bar's magnetic coupling to a driver magnet during operation.
Clause 5: The magnetic stir bar of clause 1, wherein the at least one oriented blade has a variable pitch along its length.
Clause 6: The magnetic stir bar of clause 1, wherein the orientation of the at least one blade is either left-handed or right-handed.
Clause 7: The magnetic stir bar of clause 1, wherein the magnetic stir bar is a magnetic impeller.
Clause 8: The magnetic stir bar of clause 1, wherein the at least one oriented blade includes two or more oriented blades.
Clause 9: magnetic stir bar of clause 8, wherein each of the two or more oriented blades have a variable pitch that is independently configurable.
Clause 10: A method of providing consistent stirring of fluid, providing: a plurality of vessels, each containing a magnetic stir bar configured to rotate about a rotational axis, wherein the magnetic stir bar may spin on the same axis as or on a tilted axis to a stirring axis of the magnetic stir plate; positioning the vessels containing the magnetic stir bars on a single magnetic stir plate, wherein the vessels are arranged within the operational range of a driver magnet contained within the magnetic stir plate; powering on the magnetic stir plate to rotate the driver magnet, thereby inducing a uniform rotation behavior of the magnetic stir bar in their respective vessels within the entirety of effective area of the driver magnet; and generating a mixed-flow pattern within each vessel across the magnetic stir plate, wherein the rotation of each magnetic stir bar does not interfere with the rotation of other magnetic stir bars in the adjacent vessels, allowing for simultaneous, consistent, and multi-vessel stirring across multiple vessels positioned on the same magnetic stir plate.
Clause 11: The method of clause 10, wherein the magnetic stir bar is the magnetic stir bar of clause 1.
Clause 12: The method of clause 11, wherein when the rotational axis is tilted relative to the stirring axis of the magnetic stir plate, the rotational axis and the stirring axis are non-colinear, and the magnetic stir bar exhibits a secondary dual-axis motion characterized as a precession motion, wherein the angle between the rotational axis and the stirring axis is about 0° to about 90°.
Clause 13: The method of clause 12, wherein the angle between the rotational axis and the stirring axis is 0° to about 250 or from about 220 to about 65° and from about 40° to about 90°.
Clause 14: The method of clause 11, wherein the at least one oriented blade is modifiable to accommodate specific vessel shapes.
Clause 15: The method of clause 11, wherein the core further includes a ballast, wherein the ballast is made of a ferromagnetic material that does not interfere with the magnetic stir bar's magnetic coupling to the driver magnet during operation.
Clause 16: The method of clause 11, wherein the at least one oriented blade has a variable pitch along its length.
Clause 17: The method of clause 11, wherein the orientation of the at least one blade is either left-handed or right-handed.
Clause 18: The method of clause 11, wherein the magnetic stir bar includes two or more oriented blades.
Clause 19: The method of clause 18, wherein each of the two or more oriented blades has a variable pitch that is independently configurable.
Clause 20: A magnetic stir bar including: a core, the core having a head and a tail, wherein the head and tail are on opposite ends of the core; a rotational axis, wherein the rotational axis runs along the center of the core, running through the head and the tail; at least one magnet, wherein the at least one magnet is located within the core; and two or more blades connected to the core, wherein the orientation of the two or more oriented blades is either left-handed or right-handed, wherein the two or more oriented blades have an intake zone, a transport zone, and a discharge zone, wherein the transport zone is situated between the intake zone and the discharge zone, wherein the angle between the intake zone of each of the two or more oriented blades and the rotational axis is in the range of about 300 to about 600 or about −30° to about −60°; the angle between the transport zone of each of the two or more oriented blades and the rotational axis is in the range of about 370 to about 650 or about −37° to about −65°; and the angle between the discharge zone of each of the two or more oriented blades and the rotational axis is in the range of about 450 to about 700 or about −450 to about −70°; the core further includes a ballast, wherein the ballast is made of a ferromagnetic material that does not interfere with the magnetic stir bar's magnetic coupling to the driver magnet during operation; the two or more oriented blades have a variable pitch along its length; and each of the two or more oriented blades has a variable pitch that is independently configurable.
This application claims the priority benefit of U.S. provisional application No. 63/595,978, filed Nov. 3, 2023, the contents of which are herein incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| 63595978 | Nov 2023 | US |
