Multidirectional shaker

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The invention disclosed herein relates generally to shakers for microplates, small diameter test tubes, and like-configured fluid containers, and more particularly to a multidirectional shaker of simplified construction comprising a support tray resiliently mounted above a base through a plurality of spring members arranged in differing directions, and a plurality of electromagnetic drives or mechanical drives for imparting at least bi-directional vibratory motion to the support tray in order to mix the contents of a microplate or collection of specimen tubes positioned on the support tray, irrespective of the diameter of the microplate wells or tubes.

[0003] 2. Description of the Background

[0004] The processing of biological specimens or chemical products in laboratories often requires the mixing of analytes within a container in order to carry out a desired reaction. Such containers have often comprised beakers or flasks whose contents were traditionally mixed by either manually shaking the beaker or flask, or by using a stirring rod. Other mixing apparatus have included a Teflon coated magnet placed within a beaker or flask and driven magnetically in a rotary motion to mix the beaker or flask contents. Unfortunately, manually shaking the beaker or flask provides insufficient means to control the mixing of the contents and easily results in laboratory technicians accidentally dropping the container and ruining the sample. Likewise, the use of stirring rods has required that the laboratory technician either thoroughly wash the rod between specimens in order to avoid cross-contamination, or throw away and replace disposable rods for applications with large numbers of specimens, making the rapid mixing of large numbers of specimens highly impractical.

[0005] In order to overcome these shortcomings, motor driven orbital shakers were developed which enabled a laboratory technician to place a beaker or flask on a motor driven platform that would cause the beaker or flask to travel in a continuous orbit to mix its contents. So long as the diameter of the beaker or flask holding a sample is greater than the orbit diameter of the platform, mixing of the contents will occur. For example, as shown in the schematic view of a prior art orbital mixer of FIG. 1a, the center of the flask travels in an orbital path equivalent to the orbit of the platform, and the centrifugal forces on the liquid will reverse every 180° to provide adequate mixing of the contents.

[0006] However, as the number of specimens needed to be analyzed in a given time period has grown, the quest for efficiency in the processing of such specimens has resulted in smaller and smaller sample sizes being studied, and thus smaller and smaller containers for holding those samples. Unfortunately, as smaller sized beakers and flasks were used, those orbital shakers having an orbit diameter that was larger than the beaker or flask diameter were shown to be ineffective for mixing the contents. For example, as shown in the schematic view of a prior art orbital mixer of FIG. 1b, a beaker or flask having a diameter that is smaller than the orbit diameter of the mixer simply travels in the shaker's orbit, and centrifugal forces drive the liquid contained within the beaker or flask against the side of the container which is furthest from the center of orbit. If there are any suspended solids in the liquid, they will likewise be driven against the outside wall of the container, and fail to mix with the solution. In order to alleviate this problem, a few orbital shakers have been made available having orbit diameters of as little as ⅛″.

[0007] As the need for processing greater numbers of samples in shorter amounts of time continued to grow, microplates were developed to hold multiple samples of a chemical or biological material to be analyzed in a single, compact structure having a rectangular grid of a large number of distinct “wells.” Such microplates are available today in 96-well, 384-well, and even 1536-well configurations. Likewise, racks of small diameter tubes have been developed providing a similar array of specimen-holding chambers. Obviously, the greater the number of wells or tubes in a standard microplate footprint, the smaller the diameter of the well, such that for microplates and tubes having chamber diameters of far less than ⅛″, an orbit of far less than ⅛″ would likewise be required in order to ensure proper mixing. As was true with orbital mixers for large flasks, the contents of such a small diameter tube rotating in an orbit larger than its own diameter are difficult to mix. Using an orbit larger than the well or tube diameter causes the liquid contents to move to the outside of the orbit and rise up the inner wall of the tube which is closest to the outside radius of the orbit. The contents of the tube begin to spin inside the tube with a relatively small amount of relative motion (or shearing) between adjacent layers of fluid within the walls of the tube. As the orbital speed is increased, the liquid in the tube is forced outward by centrifugal force, rising up the inner wall of the tube until it spills over the top. Given the orbit diameter limitation of only ⅛″, traditional horizontal orbital shakers have thus been ineffective in shaking microplates and tube collections having such small diameter chambers.

[0008] Given the failure of traditional orbiting mixing apparatus to provide an effective means of mixing the contents of small well microplates and small diameter tubes, attempts have been made to provide mixing apparatus specifically configured for mixing the contents of microplate wells, but unfortunately have also met with little success. For example, U.S. Pat. No. 3,635,446 to Kurosawa et al. discloses a microplate shaking device using an eccentric motor to uncontrollably vibrate a microplate holding plate through a horizontal plane. Likewise, U.S. Pat. No. 4,102,649 to Sasaki discloses a microplate shaker device which pivotally mounts a microplate to a vibration plate, and slidably mounts the microplate atop a number of props. The vibration plate is caused to vibrate by either an electromagnet or an eccentric wheel in a nonlinear, horizontal manner. Further, U.S. Pat. No. 4,264,559 to Price discloses a mixing device for a specimen holder comprising two springlike metal rods upon which a specimen holder is mounted, the rods being fixed at one end in a vertical block, and a weight positioned adjacent the opposite end of the rods. Manually plucking one of the rods imparts a “pendulum-like” vibration to both rods, and thus to the specimen holder. Finally, U.S. Pat. No. 5,921,477 to Tomes et al. discloses an agitating apparatus for a “well plate holder” which comprises a vertically-oriented reciprocating saw as a means for vertically shaking a multi-well plate, and provides agitating members comprising small diameter copper or stainless steel balls within each well.

[0009] Unfortunately, none of the known prior art devices have been able to provide controlled, multidirectional vibration to a microplate or collection of small diameter tubes in order to create vibratory motion of sufficient turbulence to thoroughly mix the well or tube contents.

[0010] Furthermore, U.S. Pat. No. 5,427,451 to Schmidt discloses a mixer which utilizes a complex, microprocessor-controlled circuit to provide oscillatory drives comprised of permanent magnets and drive coils juxtaposed therewith, with each coil being independently energized by separate variable frequency sources. The drive circuits are configured to alternately attract and repel the permanent magnets so as to provide the oscillatory motion, thus requiring actuation of the drive coils at all times during operation of the mixer. Such a construction is highly complex, requiring precise control of the timing of each drive cycle, and exhibits high energy requirements for its operation. It would be highly advantageous to provide a simplified mixing construction that has a lower energy requirement, but that can still provide consistent, reliable mixing through controlled multidirectional shaking of test specimen containers.

[0011] Moreover, effective mixing requires that the layers of fluid within the tube vigorously move relative to each other. Simply driving the tube with a small orbital motion simply rotates the fluid within the tube as a large slug, with the only appreciable relative motion occurring between the tube wall surface and the outermost fluid layer. However, suddenly stopping the orbiting motion will cause the fluid which was driven up the outer tube wall to collapse, causing greater turbulence and thus better mixing. In fact, the rapid on and off cycling of such motion causes the creation of turbulence within the tube which can greatly facilitate the mixing of layers of fluid within the tube. While mechanically driven orbiting mixers have been previously known which attempt to provide such impulse-driven mixing, such devices have not met with commercial success. For example, mechanically driven orbiting mixers have been known which are provided a timer in the motor circuit to periodically stop the unit and then start it again. Such starting and stopping of the drive mechanism is costly, creates much wear and tear on the equipment, and most importantly, is limited as to the speed with which such a device can cycle on and off due to inertia and the ability of a motor to quickly accelerate.

[0012] It would therefore be advantageous to provide an electromagnetic, multidirectional shaker of simplified construction which will ensure the efficient mixing of the contents of microplates and small diameter tubes, while keeping suspended solids truly suspended during the mixing cycle, and which is capable of rapidly cycling the driving mechanism which causes the vibratory motion so as to provide thorough mixing of the contents.

SUMMARY OF THE INVENTION

[0013] It is, therefore, an object of the present invention to provide a multidirectional microplate and specimen tube shaker which avoids the disadvantages of the prior art.

[0014] It is another object of the present invention to provide a multidirectional microplate and specimen tube shaker which can efficiently mix the contents of microplates and specimen tubes of all sizes while keeping suspended solids truly suspended during the mixing cycle.

[0015] It is yet another object of the present invention to provide a multidirectional microplate and specimen tube shaker which enables the contents of a microplate or collection of small diameter tubes to be properly mixed in a shorter amount of time than has been previously required by prior art devices.

[0016] It is still yet another object of the present invention to provide a multidirectional microplate and specimen tube shaker which enables the effective mixing of the contents of a plurality of microplates and specimen tubes during a single mixing process.

[0017] It is even yet another object of the present invention to provide a multidirectional microplate and specimen tube shaker of simplified design over prior art devices which ensures thorough mixing irrespective of the diameter of the microplate wells or tubes.

[0018] It is still yet another object of the present invention to provide a multidirectional microplate and specimen tube shaker of a more compact size than has been previously available in prior art shakers to enable such a shaker to be readily placed within a refrigerator or incubator for temperature-sensitive mixing applications.

[0019] It is still even yet another object of the present invention to provide a multidirectional microplate and specimen tube shaker which consistently applies a controlled vibration to the contents of the microplate wells or tubes so as to create sufficient turbulence within each well or tube to ensure adequate mixing.

[0020] It is even yet another object of the present invention to provide a multidirectional microplate and specimen tube shaker which enables starting and stopping the driving cycle at between 5 and 20 cycles per second.

[0021] In accordance with the above objects, an electromagnetic multidirectional shaker is provided which has a first electromagnet driving a first support panel in a first direction, and a second electromagnet driving a second support panel in a second direction. The first electromagnet is affixed to a base and is operatively attached to the first support panel which is suspended from the base via one or more first spring members. The first spring members are configured to bias the first support panel to an at-rest position after it has been displaced by the first electromagnet. The second support panel is in turn supported above the first support panel by one or more second spring members. The second electromagnet is affixed to the first support panel, and is operatively attached to the second support panel. The second spring members are configured to bias the second support panel to an at-rest position after it has been displaced by the second electromagnet.

[0022] In a first preferred embodiment, both the first and second electromagnets and spring members provide linear motions that are perpendicular to one another. Such combination of linear motions impart a horizontal elliptical motion to the second support panel, which motion may be varied in effective diameter simply by adjusting the amplitude of the vibration imparted by either one of the two electromagnets. Each of the platforms is vibrated at between 30 and 120 cycles per second, and is easily started and stopped at between 5 and 20 cycles per second to cause far more rapid collapse of the fluid on the tube wall than has been previously realized by prior art devices. Furthermore, independent control of the two electromagnetic drives enables shutting down only one of the two, thus eliminating the centrifugal force but maintaining linear shaking, in turn creating even greater turbulence within the fluid column.

[0023] In a second preferred embodiment, the first electromagnet and spring members provide linear motion, while the second electromagnet and spring members provide arcuate motion within a plane that is perpendicular to the linear direction imparted by the first electromagnet and spring members. Here, the combination of motions impart a three-dimensionally warped elliptical motion to the second support panel, which motion may again be varied in diameter by adjusting the amplitude of the vibration imparted by either one of the two electromagnets. The arcuate motion applied by the second electromagnetic drive causes a centrifugal force component in the fluid upwards and away from the center of rotation, thus providing even greater mixing.

[0024] In yet another embodiment, the electromagnetic drives may be replaced by mechanical driving means, such as a cam, while maintaining the ability to provide controlled, multi-directional mixing to the microplates or small diameter tubes to be mixed.

[0025] In each embodiment, the spring members are tuned near the natural frequency of the spring-mass system (60 Hz), and are entirely responsible for moving their respective support platforms in the reverse direction from which they are driven by the electromagnets. Thus, each electromagnet need only be energized during half of each vibration cycle, thus eliminating the need for a permanent magnet within the drive assembly and reducing the energy required to operate the assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Other objects, features, and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiment and certain modifications thereof when taken together with the accompanying drawings in which:

[0027]
FIG. 1 a is a top-down schematic view of a prior art orbital specimen shaker.

[0028]

FIG. 1

b
is a second top-down schematic view of a prior art orbital specimen shaker.

[0029]
FIG. 2 is a schematic view of the electromagnetic multidirectional shaker of the instant invention.

[0030]
FIG. 3 is a perspective view of a first preferred embodiment of the electromagnetic multidirectional shaker of the instant invention.

[0031]
FIG. 4 is a partial sectional view of the shaker of FIG. 3.

[0032]
FIG. 5 is a partial sectional view of a second preferred embodiment of the electromagnetic multidirectional shaker of the instant invention.

[0033]
FIG. 6 is a side sectional view along line A-A of FIG. 5.

[0034]
FIG. 7 is a schematic view of a mechanical multidirectional shaker of the instant invention.

[0035]
FIGS. 8 and 9 are schematic flow charts showing the operation of the shaker of FIG. 6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] As shown in the schematic view of FIG. 2, the vortexing shaker of the instant invention comprises a base 10 to which is affixed a first electromagnetic drive 20. The operative end of electromagnetic drive 20 engages a first support platform 30, which support platform 30 is in turn supported by base 10 via one or more first spring members 11. A second electromagnetic drive 25 is affixed to support platform 30, with its operative end engaging a second support platform 50. Second support platform 50 is in turn supported by support platform 30 via one or more second spring members 12.

[0037] As shown more particularly in the partial sectional view of FIG. 4, electromagnetic drive 20 preferably comprises a wire coil 40 encasing a core assembly 41a. Core assembly 41a is enclosed within a housing which in turn is rigidly attached to an upward extension 10a of base 10. An armature assembly 41b is positioned opposite core assembly 41a a sufficient distance to define an air gap 43 between the core assembly and the armature assembly. Armature assembly 41b is in turn rigidly attached to support platform 30, as set forth in greater detail below.

[0038] Air gap 43 is preset during construction of base unit 10. However, air gap 43 may inadvertently become either excessively narrow, in which case the core and armature assemblies may contact one another during the shaking operation, or excessively wide, in which case the current of the device may rise to dangerous levels. Thus, in the event that the air gap requires adjustment, a slot 42a configured to receive a screwdriver or similar device is provided within an outward extension from core assembly 41a. The extension is rotatable through use of a tool such as a screwdriver to either narrow air gap 43 (via clockwise rotation), or to widen air gap 43 (via counterclockwise rotation). The proper air gap is reached when the air gap is as narrow as possible without the core and armature assemblies contacting one another during operation. The position of the extension (and thus the width of the air gap) may be locked in place after adjustment by tightening hex nut 42.

[0039] In use, a rectified current sine wave is applied to coil 40, thus energizing the coil for half of a cycle and de-energizing the coil for the remainder of the cycle. When coil 40 is energized, core assembly 41a is magnetized and attracts armature assembly 41b. As armature assembly 41b moves towards core assembly 41a, it pulls support platform 30 towards core assembly 41 against the bias of first spring members 11 (preferably in the form of leaf springs), in turn flexing spring members 11. When coil 40 is de-energized, the magnetic pull between core assembly 41a and armature assembly 41b is released, and spring members 11 return to and pass through their at rest position, in turn pushing support panel 3 outward from core assembly 41. This cycle continues as long as power is supplied to the electromagnetic drive such that support platform 30 is vibrated in the horizontal direction.

[0040] As can readily be seen by the schematic view of FIG. 2, vibration of support platform 30 in the horizontal direction likewise causes the vibration of second electromagnetic drive 25 and support platform 50 in the same direction. Second electromagnetic drive 25 may be identical to first electromagnetic drive 20, except that second electromagnetic drive 25 is positioned to operatively engage second support platform 50 instead of first support platform 30. As support platform 30 is vibrated in the horizontal direction, electromagnetic drive 25 and second spring members 12 likewise vibrate support platform 50 in the horizontal direction at a right angle to the direction of support platform 30.

[0041] The combined vibrational movements imparted to support platform 30 may take on a variety of forms. For example, if the two platforms are driven in phase (i.e., if one platform begins its movement simultaneously with the other), then the motion generated will simply be a straight line whose motion is the vector sum of the motion of the two individual platforms. However, if the motion of the second platform is delayed until the point where the first platform has completed its travel and before returning, and the return of the first platform is delayed until the second platform completes its travel, and continues to repeat this sequence, then the final motion will become a square (assuming both platform strokes were equal, or a rectangle if not equal). By adjusting the phased relationship of the two platforms, it is easy to create a wide variety of mixing paths including squares, rectangles, straight lines, circles, and ellipses of varying ovalities. Use of the electromagnetic drives 20 and 25 of FIG. 2 easily enables an operator to electrically adjust both phase and relative amplitude of the individual platforms permitting the user to obtain the ideal multidirectional path to induce mixing of liquid in any size tube.

[0042] The electromagnetic drives 20 and 25 of the instant invention are capable of the rapid vibration of a microplate or collection of small diameter tubes with a frequency of up to 7,200 vibrations per minute. Such rapid vibration within a relatively small displacement vastly improves both the control of the mixing operation, allowing rapid vibrations without risking stability of the microplates or tubes mounted on support platform 50, and the economy of carrying out such mixing operations by shortening the amount of time a sample need be processed under an increased vibrational frequency.

[0043] As shown in the perspective view of FIG. 3 and the sectional view of FIG. 4, a first preferred embodiment of the instant invention comprises a base 10 having upwardly extending walls 10a affixed to both a front and rear end of base 10. Electromagnetic drive 20 is rigidly affixed to one of walls 10a of base 10, such as by way of a plurality of threaded members 21. Electromagnetic drive 20 is mounted so that the entirety of the housing for coil 40 is located on the exterior side of wall 10a. As shown more particularly in the partial sectional view of FIG. 4, wall 10a is provided an opening through which armature 41b extends. The end of armature 41b opposite core assembly 41a is affixed to support platform 30 at flange 31. Flange 31 has a central opening configured to receive the free end of armature assembly 41b. A compression nut 32 is threadably attached to armature assembly 41b and holds the outer end of armature assembly 41b within flange 31, such that horizontal movement of armature assembly 41b with respect to core assembly 41a imparts horizontal motion to support platform 30 in the same direction.

[0044] First spring members 11, preferably in the form of leaf springs, are mounted to the top, inner edge of walls 10a and to the bottom, outer edges of support platform 30 adjacent walls 10a so as to suspend support platform 30 above base 10, thus allowing movement of support platform 30 with respect to base 10.

[0045] Support platform 30 is provided a single upwardly extending wall 30a. Second electromagnetic drive 25 is rigidly affixed to wall 30a, such as by way of a plurality of threaded members 21. Second electromagnetic drive 25 is mounted so that the entirety of the housing for coil 40 is located on the exterior side of wall 30a. As with walls 10a, wall 30a is provided an opening through which armature 41b of second electromagnetic drive 25 extends. The end of armature 41b of second electromagnetic drive 25 opposite core assembly 41a is affixed to a downwardly extending flange 51 of support platform 50. Flange 51 has a central opening configured to receive the outer end of armature assembly 41b. A compression nut 32 is threadably attached to armature assembly 41b of second electromagnetic drive 25, and holds the outer end of armature assembly 41b within flange 51, such that horizontal movement of armature assembly 41b with respect to core assembly 41 a of second electromagnetic drive 25 imparts horizontal motion to support platform 50 in the same direction.

[0046] Once again, the phase and amplitude of each of the electromagnetic drives 20 and 25 may be varied independently of one another so as to enable support platform 50 to take on a variety of motions.

[0047] As shown in the perspective sectional view of FIG. 5 and the side sectional view of FIG. 6, a second preferred embodiment of the instant invention provides base 10, first electromagnetic drive 20, and first spring members 11 which are essentially identical to those components shown in FIGS. 3 and 4 and bearing like reference numerals. However, while the embodiment shown in FIGS. 3 and 4 provides planar elliptical motion to support platform 50 by summing first and second horizontal motions imparted by the first and second electromagnetic drives 20 and 25, the embodiment of FIGS. 5 and 6 provides a three-dimensionally warped elliptical motion to support platform 50 by summing a horizontal motion imparted by first electromagnetic drive 20 with an arcuate motion within a plane perpendicular to the horizontal motion imparted by second electromagnetic drive 25.

[0048] In the second preferred embodiment shown in FIG. 5, support platform 30 comprises a generally rectangular frame at its base having an upwardly extending flange 31 for receiving the outer end of armature assembly 41b of first electromagnetic drive 20. Support platform 30 is again suspended from base walls 10a by first spring members 11. Support platform 30 is provided a first bore hole directly below flange 31 and extending through the side wall of platform 30, and a second bore hole at the opposite side of the frame and aligned with the first opening. A shaft 70 extends through the bore holes in support platform 30. A locking pin 71 is inserted through shaft 70 at either end within the side wall of support platform 30 so as to prevent rotation of shaft 70 with respect to support platform 30.

[0049] Support platform 30 is also provided an upwardly extending bracket 75 for mounting second electromagnetic drive 25 at an angle with respect to the horizontal plane. Bracket 75 is provided an opening through which armature 41b of second electromagnetic drive 25 extends. The end of armature 41b opposite core assembly 41a of second electromagnetic drive 25 is affixed to support platform 50 at angled flange 51. Angled flange 51 has a central opening configured to receive the outer end of armature assembly 41b, and affixes the outer end of armature assembly 41b thereto, such that movement of armature assembly 41b with respect to core assembly 41a of second electromagnetic drive 25 imparts motion to support platform 50 in the same direction (i.e., at the same angle to the horizontal plane as drive 25).

[0050] Support platform 50 is pivotally attached to support platform 30 in the following manner. One side of support platform 50 is provided downwardly extending arms 52 and 53 which, at their bases, are pivotally mounted on shaft 70. A bearing or elastomer bushing 72 is preferably provided between the shaft 70 and the hollowed opening at the bottom of each of arms 52 and 53 to facilitate the free rotation of arms 52 and 53 about shaft 70. Arms 52 and 53 may be removably attached to support platform 50, such as by one or more screws, bolts, or other fastening members, or may alternately be molded in a single piece therewith. The opposite side of support platform 50 is provided downwardly extending second spring members 12 which, at their bases, are fixedly attached to shaft 70 via one or more screws, bolts, or other fastening members. With this mounting structure, support platform 50 is capable of pivotal movement about shaft 70 under the force of electromagnetic drive 25, but is biased towards an at-rest position by spring members 12. Thus, under the force of electromagnetic drive 25 and spring members 12, support platform 50 is vibrated through an arc rather than a straight line, which arc has a centrifugal force component upwards and away from the center of rotation, such that the microplate wells or tubes positioned on support platform 50 are moved in a three-dimensional circular or elliptical path whose ends are bent downwards out of the horizontal plane, further facilitating the creation of a vortex within the fluid to even further enhance mixing.

[0051] It should also be noted that the shaker of the instant invention may be operated entirely by mechanical driving means. As shown in the schematic view of FIG. 7, a mechanical multidirectional shaker of the instant invention comprises a base 10 to which is affixed a first mechanical drive 80 in the form of a rotating cam of conventional construction. The cam of first mechanical drive 80 engages first support platform 30, which support platform 30 is in turn supported by base 10 via one or more first spring members 11. A second mechanical drive 85 is affixed to support platform 30, with its cam engaging second support platform 50. Second support platform 50 is in turn supported by support platform 30 via one or more second spring members 12.

[0052] Just as with the electromagnetically-actuated embodiment of the multidirectional shaker of the instant invention, vibration of support platform 30 under the force of first mechanical drive 80 and first spring members 11 likewise cause the vibration of second mechanical drive 85 and support platform 50 in the same direction. Second mechanical drive 85 may be identical to first mechanical drive 80, except that second mechanical drive 85 is positioned to operatively engage second support platform 50 instead of first support platform 30. As support platform 30 is vibrated in the horizontal direction, mechanical drive 85 and second spring members 12 likewise vibrate support platform 50 in the horizontal direction at a right angle to the direction of support platform 30.

[0053] As shown in the schematic flow chart of FIG. 8, such a mechanical multidirectional shaker may be operated to provide varying multidirectional mixing path geometries. A motor 90 provides power output to a gear box 91, which transfers power to first mechanical drive 80 to vibrate (in combination with spring members 11) platform 30 in a first direction. Gear box 91 simultaneously transfers power to a gear differential 92, which in turn transfers power to second mechanical drive 85 to vibrate (in combination with spring members 12) platform 50 in a second direction at a right angle to the first direction. The power input into gear differential 92 may be adjusted, such as by way of a manual lever 93, to enable varying the phase of the two mechanical drives so as to provide a multitude of mixing path geometries to suit varying mixing requirements.

[0054] As shown in the schematic flow chart of FIG. 9, alternate mechanical driving means may be provided in the form of a crank 96 rotating about a crank shaft 95, and operatively connected to either of support platforms 30 or 50, via a connecting rod 97, all of conventional construction. In this case, the shaking amplitude of platforms 30 and 50 may again be easily adjusted by moving connecting rod 97 to various locations on crank 96 and in conjunction with gear differential 92 of FIG. 8, enabling a multitude of mixing path geometries to suit varying mixing requirements.

[0055] Having now fully set forth the preferred embodiments and certain modifications of the concept underlying the present invention, various other embodiments as well as certain variations and modifications of the embodiments herein shown and described will obviously occur to those skilled in the art upon becoming familiar with said underlying concept. By way of example, while each embodiment herein shows driving the two support platforms 30, 50 in orthogonal directions with respect to one another, one of the panels could alternately be driven in a direction other than at a right angle to the other panel, without departing from the spirit and scope of the instant invention. It should be understood, therefore, that the invention may be practiced otherwise than as specifically set forth herein.

Multidirectional shaker

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CPC

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