Patent Application
20070064521
The present disclosure generally relates to apparatus for rapidly vibrating sample containers or vessels and, more particularly, for mechanically lysing biological samples.
Apparatus for shaking, vibrating, or oscillating laboratory samples are generally known in the art. These devices and methods are often used to process biological samples. For example, sample cells may be deposited into a container such as a vial along with a buffer fluid and impact media, which may be provided as microbeads formed of glass, ceramic or other material. The shaking apparatus rapidly oscillates the vials so that that impact media impacts the sample material. In the case of biological samples, the oscillating movement of the vial is sufficiently rapid so that the impact media fractures the cell walls of the sample material to release genetic material, such as RNA or DNA.
Various types of methods and apparatus have been proposed for mechanically shaking samples. Some of these devices, such as the shaker disclosed in U.S. Pat. No. 6,579,002, which issued on Jun. 17, 2003 to Bartick et al., employ reciprocating pistons to provide the shaking force applied to the samples. This piston-operated device, however, is overly limited by the number of samples it may simultaneously process.
Other devices, such as those disclosed in U.S. Pat. No. 5,567,050, which issued on Oct. 22, 1996 to Zlobinsky et al., and U.S. Publication No. US 2005/0128863 A1, which published on Jun. 16, 2005 listing Esteve et al. as inventors, use an oscillating disk or plate that is capable of processing several sample as once. Typically, the plate in such devices is not rotated but instead is manipulated in a tilting, oscillatory motion. For example, the '050 patent noted above discloses a tube support disk and a means for imparting oscillating motion to the disk about a center of the disk. The drive means comprise an electric motor with an outlet shaft and a sleeve placed over the outlet shaft having an outside cylindrical surface that slopes obliquely relative to the axis of the outlet shaft. The sleeve is mounted free to rotate in the disk by means of rolling bearings in axial alignment, and the disk is associated with means for preventing it from rotating, so that when the sleeve is rotated by the motor, it causes the disk to oscillate about a center of rotation which is formed by the intersection between the axis of the motor shaft and the axis of the cylindrical outside surface of the sleeve. Tubes fixed at the periphery of the disk at equal distances from the center of rotation are thus subjected to substantially curvilinear reciprocating motion. U.S. Publication No. US 2005/0128863 A1 similarly discloses a vibration device having bearings that are oriented along an axis that is substantially perpendicular to the support disk, and therefore similarly generates bending forces on the bearings.
The currently known oscillating plate devices may place undue strain on the bearings, thereby making the bearings a wear component that may limit the useful life of the device. It is therefore desirable to provide an oscillating plate device that reduces or minimizes bending forces thereby to increase the life of the device.
In accordance with certain aspects of the disclosure, an apparatus for shaking containers holding samples is provided which includes a motor having a rotatable shaft defining a shaft axis. A rotor is coupled to and rotatable with the shaft, and at least three cam assemblies are coupled to and rotatable with the rotor. Each cam assembly includes a cam defining a support surface, and the at least three cam assemblies are oriented so that the support surfaces define a rotating plane disposed at an oblique angle with respect to the shaft axis during rotation of the cam assemblies. A socket is supported in a fixed position with respect to the rotor, and a ball is retained by and pivotable within the socket. A loading plate adapted to hold the samples is coupled to the ball to allow pivotable movement of the loading plate with respect to the rotor, the loading plate having a drive surface engaging the cam support surfaces. An anti-rotation mechanism engages the loading plate. Operation of the apparatus generates a non-rotational, oscillating motion of the loading plate which reciprocates the samples along an arcuate path.
According to additional aspects of the disclosure, apparatus for shaking containers holding samples is provided that includes a motor having a rotatable shaft defining a shaft axis, a rotor coupled to and rotatable with the shaft, and at least three cam assemblies coupled to and rotatable with the rotor. Each cam assembly includes a cam defining a support surface, and the at least three cam assemblies are oriented so that the three support surfaces define a rotating plane disposed at an oblique angle with respect to the shaft axis during rotation of the cam assemblies. A loading plate adapted to hold the samples is supported for pivotable movement with respect to the rotor. The loading plate has a drive surface engaging the cam support surfaces, and an anti-rotation mechanism engages the loading plate.
In accordance with further aspects of the disclosure, apparatus for shaking containers holding samples is disclosed which includes a motor having a rotatable shaft defining a shaft axis, a rotor coupled to and rotatable with the shaft, and a cam assembly coupled to and rotatable with the rotor, the cam assembly defining at least one support surface aligned along a rotating plane disposed at an oblique angle with respect to the shaft axis during rotation of the cam assembly. A socket is supported in a fixed position with respect to the rotor, a ball is retained by and pivotable within the socket, and a loading plate adapted to hold the samples is coupled to the ball to allow pivotable movement of the loading plate with respect to the rotor. The loading plate has a drive surface engaging the at least one support surface, and an anti-rotation mechanism engages the loading plate.
Other advantages and features of the disclosed embodiments and methods will be best understood upon reference to the accompanying drawings and detailed description that follows.
It should be understood that the drawings are not necessarily to scale and that the disclosed embodiments are illustrated using diagrammatic representations and fragmentary views. In certain instances, details may have been omitted which are not necessary for an understanding of the disclosed embodiments or which render other details difficult to perceive. It should be understood, of course, that the sample shaking apparatus is not necessarily limited to the particular embodiments disclosed herein.
Various embodiments of sample shaking apparatus suitable for agitating or otherwise processing material samples are disclosed herein. Specifically, apparatus is described for lysing and purifying nucleic acids from a biological sample using mechanical means. To prepare the sample for use in such devices, the material is typically deposited into a container such as a vial along with a buffer liquid and impact media such as microbeads. One or more sample containers are then placed in the shaking apparatus which accelerates the source material to high acceleration or “g” levels in a reversible fashion such that bead impacts with the source material cause cell disruption or fracture, thereby allowing release of nucleic acids from the cells. While the apparatus disclosed herein are described in the context of lysing biological samples, it will be appreciated that the shaking apparatus may be suitable for other materials or processes that may benefit from the advantages taught herein.
With reference to
At least one cam assembly 24 is coupled to the rotor 20 for supporting a loading plate 26 at an oblique angle with respect to the shaft axis 22, as described in greater detail below. In the illustrated embodiment, three cam assemblies 24 are coupled to the rotor 20. Each cam assembly 24 includes an axle 28 sized for insertion into a bore 30 formed in the rotor 20 (
The loading plate 26 is supported from the frame 18 in a manner which allows it to freely pivot about a center point. In the illustrated embodiment, the loading plate 26 is coupled to the frame 18 by a ball joint 40. The ball joint 40 includes a socket 42 coupled to the frame 18 and formed by a socket block 44 and retainer plate 46. The socket 42 defines a partially spherical receptacle 48 sized to receive ball member 50. A backing plate 52 is coupled to the ball member 50 and a fastener 54 is inserted through an aperture formed in the loading plate 26 and threadably received by a threaded aperture formed in the ball member 50, thereby to couple the loading plate to the ball member 50. The pivotable engagement between the ball member 50 and the socket 42 enables the loading plate 26 to freely pivot about a center point CP of the ball member 50. The ball-joint may be formed of a self-lubricating plastic material (such as PEEK), or other similar material.
The loading plate 26 includes a drive surface 56 adapted to engage the driving wheels 32. In the illustrated embodiment, the driving wheels 32 each have a beveled outer surface for engaging the loading plate 26 and the loading plate 26 includes a wear ring 58. As best shown with reference to
The loading plate 26 further includes a plurality of apertures 62 located at a periphery thereof for receiving sample material. In the illustrated embodiment, the apertures 62 are round and sized to receive cylindrical vials (not shown) which hold the sample material and any impact media. The apertures 62 may be sized to produce an interference or near-interference fit with the vials, thereby to hold the vials on the loading plate during operation. Alternatively, well-known locking mechanisms may be employed to retain the vials on the loading plate.
An anti-rotation mechanism, such as spring 64, is provided for preventing the loading plate from rotating during operation. As best shown in
In operation, when the motor 12 of the shaking apparatus 10 is energized, the rotor 20 and attached cam assemblies will rotate with the motor shaft 14. The driving wheels 32, which engage the wear ring 58 of the loading plate 26, orient the loading plate 26 at an oblique angle with respect to the motor shaft axis 22. As a result, a first portion of the loading plate 26 is located above than a horizontal reference line while an opposing portion of the loading plate 26 is located below the horizontal reference line. As the driving wheels 32 rotate, the locations of the higher and lower portions of the loading plate 26 will change. Accordingly, when the driving wheels 32 rotate 180°, the portion that was below the horizontal reference point will be above the horizontal reference point, and vice versa. By rapidly rotating the driving wheels 32, the loading plate 26 will move in a tilting, oscillatory motion that reciprocates the sample containers in a reversing arcuate path, thereby processing the sample material inside the vials as desired. The spring 64 prevents the loading plate 26 from rotating, thereby causing the loading plate 26 to move in a non-rotational oscillating manner.
Another shaking apparatus embodiment is illustrated in
More specifically, and as best shown in
Yet another embodiment of a shaking apparatus 210 is illustrated in
It will be appreciated that the angle between the tilt axis and the motor shaft axis is directly proportional to the stroke distance along which the sample traverses during operation. Consequently, the apparatus may be adapted to couple with several different rotor assemblies, each of which producing a different tilt axis, thereby to provide a single apparatus capable of generate varied stroke lengths.
This embodiment also employs the anti-rotation spring 64 noted above with respect to the embodiment of
While only certain embodiments have been set forth, alternative embodiments and various modifications will be apparent from the above description to those skilled in the art. These and other alternatives are considered equivalents and within the spirit and scope of this disclosure.
