Patent Publication Number: US-2004042936-A1

Title: Cross-wave sonicator

Description:
BACKGROUND OF THE INVENTION  
       [0001] 1. Field of the Invention  
       [0002] The present invention relates to a sonicator for sonicating (disintegrating) cells or tissues with ultrasonic waves so as to remove DNA, RNA or other substances therefrom.  
       [0003] 2. Description of the Related Art  
       [0004] Various studies have been made recently with development of biotechnology, and sonicators are utilized in operations of removing DNA, RNA or other substances from cells and tissues. In these operations, it is desirable for operators to carry out sonication of samples infected with BSE or other pestiferous diseases with the samples being sealed in tubes.  
       [0005] Schemes of conventional sonicators will be explained referring to FIGS. 4 and 5. FIG. 4 shows a sonication method in which a sample  82  contained in a tube  80  is disintegrated by bringing an ultrasonic wave transducer  81  into direct contact with the sample. FIG. 5 shows a method in which a sample  82  sealed in a plastic vessel  84  is as such exposed to an ultrasonic wave from an ultrasonic wave transducer  83 .  
       [0006] Of these two methods described above, the former method (direct exposure) has been predominantly used. Because the vessels including the tube  80  are made of plastics, and an ultrasonic wave has the intrinsic property that it can hardly penetrate flexible materials, so that the energy of the ultrasonic wave is halved when it propagates through such plastic vessels.  
       [0007] In the method shown in FIG. 4, it is difficult to operate under aseptic condition, since the ultrasonic wave transducer  81  is brought into direct contact with the sample  82 . Besides, the greater the number of samples is, the poorer becomes the workability and the higher becomes the liability of contamination.  
       [0008] Meanwhile, in the method shown in FIG. 5, an ultrasonic wave is radiated in one direction to suffer a great loss of energy, disadvantageously.  
       SUMMARY OF THE INVENTION  
       [0009] The present invention is proposed with a view to solving-the problems inherent in the prior art examples described above. According to one aspect of the present invention, the cross-wave sonicator is provided with a processing tank having side walls, the lower portions of which are bent inward to form inclined walls respectively. The sonicator is also provided with ultrasonic wave transducers attached onto external surfaces of the inclined walls, which radiate ultrasonic waves such that they intersect orthogonally with each other within the processing tank to generate high energy around samples to be treated, thus achieving sonication of the samples.  
       [0010] According to another aspect of the present invention, the inclined walls are designed to have an angle of 45° with respect to the side walls, and the ultrasonic wave transducers are attached orthogonally to the inclined walls so that ultrasonic waves generated from the transducers intersect orthogonally with each other.  
       [0011] Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings illustrated by way of examples the principles of the invention.  
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0012] The invention together with the objects and advantages thereof may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which:  
     [0013]FIG. 1 is a schematic front view of a cross-wave sonicator according to one embodiment of the present invention;  
     [0014]FIG. 2 is a plan view of the cross-wave sonicator shown in FIG. 1;  
     [0015]FIG. 3 is an explanatory drawing showing actions of the cross-wave sonicator shown in FIG. 1;  
     [0016]FIG. 4 is an explanatory drawing showing an example of prior art sonicator; and  
     [0017]FIG. 5 is an explanatory drawing showing another example of prior art sonicator. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     [0018] The cross-wave sonicator according to one embodiment of the present invention will be described referring to the attached drawings. FIG. 1 is a schematic front view of the cross-wave sonicator; FIG. 2 is a plan view of the cross-wave sonicator; FIG. 3 is an explanatory drawing showing actions of the cross-wave sonicator.  
     [0019] The cross-wave sonicator  1  contains a processing tank  10  for carrying out sonication and also contains a pair of oscillators  41 , a cooling fan  43  and an operation panel  42 .  
     [0020] The processing tank  10  is a substantially rectangular water bath and is designed to have a structure such that a container  20  to be described later can be mounted on top of it. A pair of vertical side walls  11  of the processing tank  10  are bent inward at around the middle by an angle α to form a pair of inclined walls  12  respectively. The lower extremity of each inclined wall  12  connects to a horizontal bottom plate  13 . The angle α is most preferably 45° as exemplified in this embodiment. However, the angle α is not limited to 45°.  
     [0021] An ultrasonic wave transducer  18  is attached to the external surface of each inclined wall  12  to be orthogonal to it. A diaphragm  17  is located on the internal side of each inclined wall  12 .  
     [0022] While a pair of inclined walls  12  are formed in the right and left side walls  11  in this embodiment, the front and back side walls may also have inclined walls. In this case, the processing tank  10  has four inclined walls  12 , and four ultrasonic wave transducers  18  are attached to these four inclined walls, respectively.  
     [0023] The container  20  is a rack for setting tubes  23  on the processing tank  10  and has a pair of holders  21  and  22  secured therein. The holders  21  and  22  hold the tubes  23  with the lower end portions thereof being immersed in water  19 . In this embodiment, the holders hold eight tubes  23 . This container  20  is positioned at the center of the processing tank  10  where samples can be exposed most fully to ultrasonic waves.  
     [0024] Actions of the cross-wave sonicator of this embodiment having the constitution as described above will be described.  
     [0025] First, tubes  23  are set in the holders  21  and  22  of the container  20 , and the container  20  is mounted on the processing tank  10 . The tubes  23  each contain an aqueous solution  25  and a sample  24  to be sonicated. The lower end portions of the tubes  23  are immersed in water  19  so as to allow transmission of ultrasonic waves thereto with the aid of water.  
     [0026] Then, the oscillators  41  are actuated to operate the ultrasonic wave transducers  18  and generate ultrasonic waves. The ultrasonic waves are intensified when they go through the diaphragms  17  respectively to progress further toward the tubes  23 .  
     [0027] It should be noted here that the ultrasonic waves V passed through the pair of diaphragms  17  progress orthogonal to the respective inclined walls  12 , as shown in FIG. 3, so that the ultrasonic wave radiated from one ultrasonic wave transducer  18  intersects orthogonally with the ultrasonic wave radiated from the other ultrasonic wave transducer  18 . The intersection of the ultrasonic waves is preset around the water surface at the center of the processing tank  10 , and tubes  23  are arranged as described above around the intersection area.  
     [0028] The ultrasonic waves V progress through the water  19  in the processing tank  10  to reach the tubes  23 , and they progress further through the aqueous solution  25  to reach finally the sample  24  in each tube  23  and sonicate it.  
     [0029] In FIG. 3, R means the range where cavitation was caused by the ultrasonic waves, and S means the range where cavitation occurred intensively.  
     [0030] The sonicator according to this embodiment exhibits the following effects.  
     [0031] In the cross-wave sonicator  1 , since the ultrasonic waves radiated through the right and left diaphragms  17  intersect orthogonally with each other to impinge upon the samples  24  in the tubes  23 , the ultrasonic energy is intensified. Thus, the sonicator  1  can effectively perform sonication of the samples  24  even if the tubes  23  or vessels are made of a flexible plastic material.  
     [0032] As has been described heretofore, the cross-wave sonicator of the present invention outputs high ultrasonic energy in spite of its simple structure and can achieve sonication of samples efficiently.  
     [0033] It should be apparent to those skilled in the art that the present invention may be embodied in many other specific forms without departing from the spirit or scope of the invention.