Abstract:
An apparatus for sensing a blood sample contained in a sample container, the blood sample being separated into a serum and a clot by a separating medium, the apparatus comprising a first sensing unit which senses the separating medium using an infrared sensor and outputs a first sensing signal, a second sensing unit which senses the serum and the clot using an infrared sensor and outputs a second sensing signal, a driving unit which moves the first sensing unit and the second sensing unit relative to the sample container, a position sensing unit which outputs a position sensing signal indicating a position of the first sensing unit and a position of the second sensing unit, and a controller which calculates positions of the separating medium, the serum and the clot in response to the first sensing signal, the second sensing signal and the position sensing signal.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2004-083110, filed Mar. 22, 2004, the entire contents of which are incorporated herein by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a method and an apparatus for sensing a blood sample contained in a sample container.  
         [0004]     2. Description of the Related Art  
         [0005]     In order to separate blood into a serum and a clot accurately using a centrifuge or the like, a test tube  1  containing a silicon-separating medium B is used. If the blood in the test tube  1  is centrifuged, it is separated into a serum A and a clot C by the silicon-separating medium B, and air D is sealed in between the serum A and a stopper  2 . A blood sample is thus obtained in the test tube  1  as shown in  FIG. 1 .  
         [0006]     When the above blood sample is processed to aliquot the serum A in the test tube  1  by sticking a nozzle of an aliquot/pipette instrument into the stopper  2  to reach the serum A, it is required to sense the following: separation positions of the blood sample, i.e., position e of separation between air D and serum A, position f of separation between serum A and silicon-separating medium B and position g of separation between clot C and silicon-separating medium B, separation ranges of height d of air D, height a of serum A and height b of silicon-separating medium B, and height h of stopper  2 .  
         [0007]     The air D, serum A and silicon-separating medium B differ in height and their heights d, a, and b vary with the amount of the blood sample in the test tube  1 . If these heights are not sensed accurately, the following problems will occur: the nozzle of the aliquot/pipette instrument contacts the silicon-separating medium B and sucks it up, and the nozzle stops in the middle position of the serum A to leave the serum A on the top of the silicon-separating medium B.  
         [0008]     A blood sample sensing apparatus as described above is disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2002-323479. In this apparatus, a sensing coil is fitted into a test tube  1  that contains a serum A and a clot C separated by a silicon-separating medium B. The sensing coil moves relative to the test tube  1  while being supplied with a measurement signal having a given frequency. A position between the serum A and clot C is sensed based on the level variations of the measurement signal.  
         [0009]     The sensing apparatus disclosed in the above Publication adopts a magnetic sensing means using a sensing coil. It is thus difficult to sense respective separation positions of a blood sample, respective separation ranges of height d of air D, height a of serum A and height b of silicon-separating medium B, and height h of stopper  2 . The above sensing apparatus also has the problems that its configuration is complicated and its costs become high.  
       BRIEF SUMMARY OF THE INVENTION  
       [0010]     In accordance with one embodiment of the present invention, there is provided a method for sensing respective separation positions and separation ranges of a blood sample with high precision and an apparatus for doing the same with simple configuration.  
         [0011]     An apparatus for sensing a blood sample, comprises a sample container which contains a blood sample that is separated into a serum and a clot by a separating medium, a first sensing unit which senses the separating medium using an infrared sensor and outputs a first sensing signal, a second sensing unit which senses the serum and the clot using an infrared sensor and outputs a second sensing signal, a driving unit which moves the first sensing unit and the second sensing unit relative to the sample container, a position sensing unit which outputs a position sensing signal indicating a position of the first sensing unit and a position of the second sensing unit, and a controller which calculates positions of the separating medium, the serum and the clot in response to the first sensing signal, the second sensing signal and the position sensing signal. 
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
       [0012]     The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the invention.  
         [0013]      FIG. 1  is an illustration of the internal state of a conventional test tube that contains a separated blood sample;  
         [0014]      FIG. 2  is a diagram showing a configuration of a sensing apparatus according to a first embodiment of the present invention, which senses a blood sample contained in a test tube;  
         [0015]      FIG. 3  is diagram showing a configuration of a sensing apparatus according to a second embodiment of the present invention, which senses a blood sample contained in a test tube;  
         [0016]      FIG. 4  is a schematic plan view of first and second sensing units that are arranged at the same level in the vertical direction of the test tube; and  
         [0017]      FIG. 5  is an illustration of position sensing signals that are supplied to an arithmetic unit from a reception element of each of the first and second sensing units. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0018]     Embodiments of the present invention will be described with reference to the accompanying drawings.  
         [0000]     (Configuration of First Embodiment)  
         [0019]      FIG. 2  shows a blood sample sensing apparatus according to a first embodiment of the present invention. A test tube  1  contains a blood sample to be sensed. As shown in  FIG. 1 , in the test tube  1 , the blood sample is separated into a serum A and a clot C by a silicon-separating medium B, and air D is sealed in between the serum A and a stopper  2 . A test tube holding stage  10  is a holding unit for holding the test tube  1  vertically.  
         [0020]     Referring to  FIG. 2 , first and second sensing units  11  and  12  are arranged at different levels in the vertical direction of the test tube  1 . The first sensing unit  11 , which is located higher than the second sensing unit  12 , includes an infrared ray radiation element  11   a  that radiates infrared rays and an infrared ray reception element  11   b  that receives infrared rays from the element  11   a . These elements  11   a  and  11   b  face each other with the test tube  1  therebetween. The elements  11   a  and  11   b  are held by their respective element holding members  3 . As the members  3  move up and down, the elements  11   a  and  11   b  move up and down at a constant speed so that the first sensing unit  11  can sense of the stopper  2  and the silicon-separating medium B. The first sensing unit  11  is, for example, an infrared sensor for radiating and receiving infrared rays whose wavelength ranges from 600 nm to 800 nm and sensing the stopper  2  and the silicon-separating medium B.  
         [0021]     The second sensing unit  12  is located lower than the first sensing unit  11 . The unit  12  includes an infrared ray radiation element  12   a  that radiates infrared rays which differ in wavelength from those of the first sensing unit  11  and an infrared ray reception element  12   b  that receives infrared rays from the element  12   a . These elements  12   a  and  12   b  also face each other with the test tube  1  therebetween. The elements  12   a  and  12   b  are held by the element holding members  3 , respectively. As the members  3  move up and down, the elements  12   a  and  12   b  move up and down at a constant speed together with the first sensing unit  11  so that the second sensing unit  12  can sense the air D, the serum A and the clot C. The second sensing unit  12  is, for example, an infrared sensor for radiating and receiving infrared rays whose wavelength ranges from 1400 nm to 1700 nm and which reacts on the molecules of water, and sensing the air D, the serum A and the clot C.  
         [0022]     A driving unit  5  moves the element holding members  3  of the first and second sensing units  11  and  12  up and down so as to slide along a vertical guide (not shown). The driving unit  5  includes a screw shaft  6 , a driving motor  7  and reduction gears  8  and  9 . The screw shaft  6  is inserted into a screw piece  4  of the element holding member  3  and its top and bottom ends are supported such that it can rotate on its axis. The driving motor  7  adopts a stepping motor, a servo motor or the like and rotates forward and backward. The reduction gears  8  and  9  reduce the rotation of the driving motor  7  and transmit it to the screw shaft  6 .  
         [0023]     An arithmetic unit  15  is electrically connected to the driving motor  7  and the infrared ray reception elements  11   b  and  12   b  of the first and second sensing units  11  and  12 . The unit  15  includes, for example, a memory as a storage unit. The unit  15  processes sensing signals of the serum A, the clot C and the silicon-separating medium B, which are output from the infrared ray reception elements  11   b  and  12   b  when they sense the serum A, the clot C and the silicon-separating medium B, and a position (height) sensing signal supplied from the driving motor  7 . Thus, the unit  15  calculates respective separation positions e, f and g of the blood sample in the text tube  1 , respective separation ranges of height d of air D, height a of serum A and height b of silicon-separating medium B, and height h of the stopper  2 , and stores these information items in the memory.  
         [0000]     (Operation and Advantages of the Embodiment)  
         [0024]     A method of sensing a position of a blood sample using a sensing apparatus having a configuration as described above will be described with reference to  FIG. 2 . At first sample-contained test tube  1  is conveyed to the sensing apparatus by a conveyor unit such as a conveyor belt (not shown). Then, the test tube  1  is moved to the test tube holding stage  10  of the sensing apparatus by a robot arm (not shown) and held thereon vertically. At this time, the element holding members  3  of the first and second sensing units  11  and  12  move up and stop in the uppermost position.  
         [0025]     As the driving motor  7  rotates in the forward direction, the screw shaft  6  rotates in the same direction and the first and second sensing units  11  and  12  move down at a constant speed. The infrared ray radiation element  11 a of the first sensing unit  11  radiates infrared rays having a wavelength of 600·nm to 800 nm toward the infrared ray reception element  11   b , while the infrared ray radiation element  12   a  of the second sensing unit  12  radiates infrared rays having a wavelength of 1400 nm to 1700 nm toward the infrared ray reception element  12   b.    
         [0026]     As the first and second sensing units  11  and  12  move down, the reception elements  11   b  and  12   b  supply the arithmetic unit  15  with the signals for sensing the serum A, the clot C, the silicon-separating medium B, etc, as shown in  FIG. 5 . The driving motor  7  supplies the unit  15  with the position (height) sensing signal. The unit  15  processes these signals to calculate respective separation positions e, f and g of the blood sample in the text tube  1 , respective separation ranges of height d of air, height a of serum A and height b of silicon-separating medium B, and height h of the stopper  2 , and stores these information items in the memory.  
         [0027]     The above information items can be sensed as described above. If the sum of heights h, d and a is calculated, an amount of movement of the nozzle of an aliquot/pipette instrument can be obtained. If the serum A is aliquoted based on this amount of movement, the nozzle of the instrument can be prevented from contacting the silicon-separating medium B and sucking it up, and the serum A can be pipetted without remaining on the silicon-separating medium B.  
         [0028]      FIG. 3  shows a blood sample sensing apparatus according to a second embodiment of the present invention. The sensing apparatus includes first and second sensing units  11  and  12 . A test tube  1  and a holding arm  10   a  for holding the test tube  1  vertically are moved up and down by the same driving unit  5  as that of the first embodiment. The first and second sensing units  11  and  12  are fixed on a substrate  13 . The test tube  1  stops in the uppermost position with its top end portion held by the holding arm  10   a , and moves down through a hole  13   a  of the substrate  13 . The holding arm  10   a  has a screw piece  14  into which a screw shaft  6  is inserted and moves up and down so as to slide along a vertical guide (not shown). Since the other components have the same configuration and function as those of the first embodiment, they are denoted by the same reference numerals and their detailed descriptions are omitted.  
         [0029]     The first and second sensing units  11  and  12  can be changed in position to each other and, in other words, the second sensing unit  12  can be arranged higher than the first sensing unit  11 . Furthermore, they can be arranged at the same level in the vertical direction of the test tube  1  such that their infrared ray radiation directions cross at right angles as shown in  FIG. 4 .  
         [0030]     In the first and second embodiments, a test tube is used as a sample container. However, the sample container is not limited to the test tube. Another sample container can be used if it can contain a blood sample that can be sensed by the sensing apparatus. If a container exclusive to the sensing apparatus is manufactured or a sample container suitable thereto is selected, the apparatus can be increased in sensing accuracy and sensing speed.  
         [0031]     Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents. For example, the first and second sensing units  11  and  12  in the above embodiment merely output the sensing signals indicating whether or not the serum A, the clot C or the silicon-separating medium B is present between the infrared ray radiation element  11   a  or  12   a  and the infrared ray reception element  11   b  or  12   b . Thus, the arithmetic unit  15  calculates the position of the serum A, the clot C or the silicon-separating medium B based on the sensing signals and the position (height) sensing signal from the driving motor  7 . However, if the first and second sensing units  11  and  12  incorporates a position detecting function and receives the position (height) sensing signal from the driving motor  7 , the first and second sensing units  11  and  12  can directly output the position of the serum A, the clot C or the silicon-separating medium B and the arithmetic unit  15  can be omitted.