Note: Descriptions are shown in the official language in which they were submitted.
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DESC~IPTION
SUCTION HEAD FOR CARRYING REACTION CUPS USED
IN BIOCHE~ICAL REACTION ANALYZING APPARATUS
Technical Field:
The present invention relates to a suction
head for carrying reaction cups to be used suitably in,
for example, an analyzing apparatus for detection and
measurement oE a very small amount of biologically active
substances contained in specimen solution, particularly
EIA (Enzyme Immuno Assay) apparatus.
Background Art:
The present invention will be described below
by referring to its typical application, Enzyme Immuno
Assay method, wherein enzyme is used as a label for an
antigen-antibody reaction complex. Recently, active
efforts have been made in the research and development
of the EIA method, as one of immunological techniques
for detecting and measuring very small amounts of
biologically active substances.
There are many types of EIA methods. A method
is known typically wherein an amount of antibody or
antigen in specimen solution is quantitatively analyzed
by contacting the solution with antigen or antibody fixed
on an insoluble carrier and a conjugate labeled with
enzyme as to produce complex through the reaction of
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immune reaction, contactiny the produced complex with
substra-te which can produce opticall~ detectable
variation in its characteristics (for example,
fluorescen-t intensity) under the activating action of
the enzyme, and determining the optical variation of
the substrate.
Since these analytical operations were
generally performed on many specimens, analyzing
apparatuses comprising a number of reaction cells
such as the known micro-titre plate has been conven-
tionally provided for practical use.
~owever, these operations by using micro-
titre plate present inconvenience that they require
time-consuming preparation for the analyzing process,
if assays of different analytes are applied to
individual samples, though they are effectively
appropriate to assay of the same analyte or the same
group of analytes for each specimen.
In these circumstances, the inventors have
completed such a system as described below to improve
the operability and the efficiency of operation in
the practical applications of the EIA method.
In accordance with a particular embodiment
of the invention there is provided a biochemical
reaction analyzing apparatus having a reaction cup
and a suction head for carrying said reaction cup,
wherein said cup has a hollowed portion providing a
reaction cell for biochemical reactions and a top
face covered and sealed with a sheet, said suction
head being engageable with the sealed top face of the
cup, said suction head comprising: an annular
elastic suction pad at its lower end which engages
with the top face of the cup to engage with the
periphery of the top face of the cup, and a head body
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provided wi-th an air suc-tion and discharge opening
formed inside said suction pad, said head body defin-
ing a cylindrical cavity at its lower end and an air
passage at its upper end, said cylindrical cavity
having a diameter which is substantially equal to a
diameter of said opening, said air passage ha-ving a
diameter which is smaller than the diameters of said
cylindrical cavity and said opening, said cylindrical
cavity extending up from said opening in a vertical
direction and having a length in the vertical
direction sufficient to permit a stream of discharged
air from said air passage to be guided downward onto
the reaction cup through an entire cross-sectional
area of said opening.
This system is used with sealed cups,
filled with a specific antibody (or antigen) fixed
on an insoluble carrier (for example, bead) and
conjugate (this cup will be referred to as "reaction
cup" hereinafter). A group of reaction cups is
prepared for each analyte. Before the analyzing
operations are undertaken, this system can select
the reaction cups corresponding to
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the required analytes for each specimen from among the
prepared groups of reaction cups, and carry them on a
transport block and then transport to an analyzing
section.
Such a system is characterized by the fact
that it can be very effectively used for an automated
analyzing apparatus. For example, if the system comprises
a cup lifter of x/y scanning type in a storage containing
a group of reaction cups corresponding to each of many
analytes and can repeat the sequential operations of
hanging a specific reaction cup and carrying it onto
the transport block by running the cup lifter over the
storage, the use of an electronic control unit will allow
the cup lifter to arrange the reaction cups far the
respective analytes automatically and mechanically on
the transport block followed to the required data stored
in the control unit.
A suction head, for example, as shown in Fig. 4,
can be used as a part of the cup lifter for the system
as described above. However, the use of this suct1on
head in the:system encountered the problems as described
below.
The suction head as shown in Fig. 4 comprises
a head body ll, a suction pad 12 of elastic ring fixed
on the lower end of the head body 11, and an air
passage 13 provlded with an air suction port 14 opened
at the central bottom part of the elastic pad 12 and
another port 15 connected to a pressure reducing source 17
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through a change-over valve 16. This suction head
attracts the reaction cup as described above at the lower
end of the suc-tion pad 12 by the aid of vacuum, and hangs
it by suction. Although there was no problem in suction
hanging of the reaction cup, the suction pad encountered
a problem that the reaction cup 19, very light, is hardly
separated from the suction pad 12 because of its adhesion
when it is placed down on the transport block. As shown
in Fig. 5, the change-over valve 16 was switchably
connected between the pressure reducing source 17 and
a pressure source 18, which permits to discharge air
through the suction port 14 for the forced separation
of the cup 19 from the suction pad 12. However, this
configuration as shown in Fig. 5 sometimes caused a
difficulty in the separation of the cup 19 from the
suction pad 12.
The present invention was produced to provide
a device effectively applicable to the system using
reaction cups as described above. Particularly, an
objective of the present invention is to provide a suction
head which can be used to seIect and carry the reaction
cup, as used 1n the above-described system, in a storage
of many reaction cups, particularly a suction head which
can provide the stable operations of lifting up and
placing down the reaction cup.
Disclosure of Inventlon:
AcGording to the present invention produced
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to accomplish this object, the suction head for carrying
reaction cups used in a biochemical reaction analyzing
apparatus is characterized by the facts that it can engage
with the sealed-up top face of a reaction cup, which
comprises a hollow body constituting a reaction cell
for biochemical reaction as well as a top covered and
sealed up with a sheet, and carry the reaction cup by
hanging it by suction, and it comprises a suction pad
of elastic ring at its lower end to engage with the
periphery of the reaction cup top face, a head body
provided with an air suction and discharge opening formed
inside the suction pad, and a cylindrical cavity
approximately equal in diameter to the opening and
extending up from the opening in the axial direction
of the head body enough long to guide the discharged
air stream downward.
In the suction head thus constructed, the head
body provided with the cylindrical cavity may be provided
with a plurality of circumferential grooves in its inner
wall. It is also effective that a weight of light load
engageable with the top of the reaction cup freely moves
vertically in the cylindrical cavlty or passage so as
to exert a mechanical downward force on the reaction
cup to be placed down in position. It is also effective
to exert a downward force on the weight by using a spring
of small load.
The present invention utilizes this construction
of the suction head for the reason as described below.
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The inventors found that in the construction
as shown in Fig. 5, if the suction of the reaction cup
by the suction pad is caused by the horn type air suction
and discharge port of the head body, the discharge air
tends to suck the reaction cup up to the suc-tion pad
according to the Bernoulli's principle. Based upon this
knowledge, the inventors invented the construction of
the suction head according -to the present invention
wherein the effec-t of suction given by the discharge
air on the reaction cup was eliminated.
For the EIA process, the present invention
uses a reaction cup in preference which is filled up
with a specific antibody (or antigen) fixed on the
surfaces of synthetic resin beads as material contributing
to the immunological reaction. However, the reaction
cup may not be limited to such a cup.
In many cases, the reaction cup is a cup of
transparent or opaque synthetic resin having a capacity
as small as several milliliters or less and a weight
of approximately lOg or less.
The sealing sheet over the top of the reaction
cup is a foil that is so fragile as to be easily broken
by a sharp tool or equivalent, or general~ly a metallic
foil such as aluminium or a plastic film coated with
aluminium. However, the material of the sealing sheet
is not limited to them. The sealing foil must be tightly
attached by the heat~sealing or the bonding onto the
periphery of the top opening.
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Brief Description of Drawings:
Fig. l(a) is a fron-t view illustrating the
construction of an embodiment of suction head according
to the present invention.
Fig. l(b) is a partial enlarged view with a
sectional view in the right half part showing the detail
of the suction head as shown in Fig. l(a).
Figs. 2(a) to 2(c) are partial enlarged views
with sectional views in the right half parts showing
the other embodiments of suction head according to the
present invention.
Fig. 3 is a perspective illustrating the
construction of the reaction cup according to the present
invention.
Fig. 4(a) is a frontal view showing a
conventional suction head.
FigO 4(b)~is a partlal enlarged view with a
sectional view in the right half part showing the detail
of the suction head as shown in Fig. 4(a).
Flg. 5 is a frontal view showing another
conventional suction head.
Best Mode for Carrylng Out the Invention:
The present invention will be described below
by using the embodiments as shown in the drawlngs anne~ed
hereto.
In Fig. 1, the head body 1 of the suction head
is supported by a movable support (not shown) 50 that
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it can be moved in a horizontal plane. This movable
support is generally controlled by a proper electronic
control unit so that it can be horizontally and vertically
moved to scan, lift and lower the reaction cup.
At the lower end o~ the head body 1, a suction
pad of elastic ring 2 is fixedly mounted so that the
lower end of the pad 2 can engage with the top of the
reaction cup 19.
An air passage 3 is provided with an air suction
and discharge port 4 formed as a larger opening at the
lower end of the head body 1 (inside the suction pad 2).
The other end 5 of the air passage 3 is switchably
connected to a pressure reduclng source 7 and a pressure
source 8 through a change-over valve 6.
This embodiment of suction head according to
the present invention is characterized by the fact that
a cylindrical cavity 4a having the same diameter as the
air suction and~discharge port 4 is formed up from the
air suctlon and discharge port 4 (in the axial dlrectlon
of the head body) at the predetermlned length. A ~
plurality of circumferential grooves~4b are formed in
the inner wall surrounding the cylindrlcal cavlty~4a.
The cylindrical cavity 4a constitutlng a part
of the air passage 3 is effective to separate the reaction
cup 19 forcedly from the suction pad 2 by the aid of
the~air discharge pressure, when the reaction cup 19
is placed down on a transport block. To elimlnate the
effect of suction according to the Bernoulli's principle
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as described above, it is desirable tha-t the area on
the top face of the sealing sheet over the reaction cup
where the discharged air is blown down is as large as
possible, that the area on the top face of the sealing
sheet where the air flows in parallel to the top face
of the sheet is thus as small as possible, and that the
diameter of the former area is set according to the
conditions where the reaction cup can be separated from
the suction pad. In general, the diameter of the
air-blown area is desirably 50% to 90% of the suction
pad inner diameter.
It is also deslrable that the axial length
of the cylindrical cavity 4a is set so as to meet the
conditions in which the air discharged through the narrow
air passage 3 is blown down on the reaction cup through
the entire cross sectional area of the discharge port 4.
In general, the axial length of the cylindrical cavity 4a
is desirably equal to or greater than 1/2 the diameter
of the discharge port 4.
The air suction force and the air discharge
force used for the lifting of the reaction cup by the
suction head according to this embodiment is generally
approximately -0.9 atom to -0.2 atom and
approximately 0.1 atom to 2 atom respectively.
The reaction cup lifting test was conducted
by uslng this embodiment of suction head according to
the present invention in the conditions as described
below, and the results were compared with the results
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of the same -test on the suction head as shown in Fig. 5
(substantially identical with the suction head according
to this embodiment, except that it has no cylindrical
cavity). The comparison showed that the working stability
was higher for this embodiment, as indicated in Table 1.
The embodiment according to the present invention:
Reaction cup
Top diameter of aluminium foil seal: 14 mm~
Bottom diameter of cup : 10 mm~
Weight : 1 g
Suction head:
Air passage
Diameter : 2 mm~
Air suction pressure : -0.5 atom
Air discharge pressure: 0.5 atom
Cylindrical cavity
Diameter : 5 mm~
Axial length : 20 mm
Peripheral grooves: 1 mm (3 grooves)
Suction pad (of rubber)
Inner diameter : 8 mm~
Outer diameter : 14 mm~
The length of the projection
from the lower end of the
head body : 0.5 mm
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Table 1
Of 100 reaction cups moved from the storage
into a transport block, the number of reaction
cups failed in movement
Conventional suction head 1 to 10 or
(Fig. 5) more
This embodiment (Fig. 1) 1 or less
The present invention is not limited to the
embodiment as described above. As it is shown in
Figs. 2(a) to 2(c), a vertically movable weight may be
freely moved in the cylindrical cavity 4a in the head
body 1 and engaged with the top face of the reaction
cup to facilitate the separation of the reaction cup
from the suction pad 2. 4c is a stopper flange part
whlch projects at the lower end of the head body in the
radial and inward direction of the cylindrical cavity 4a
to prevent the weight from slipping off.
Fig. 2(a) shows an embodiment using a pin type
weight 9a~. Flg. 2(b) shows an embodiment using a ball
type welght 9b. Fig. 2(c) shows an embodiment using
a pin type weight 9a combined with an energizing spring 10
whlch exerts a sprlng force~down on the weight 9a. The
weight may be;of steel, for example, and
approximateIy 0.5 g in weight. The material and weight
are not limited. If the energizing spring 10 is used,
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it is desirable that the spring force is not grea-ter
than 1/2 the suction force exerted by the suction pad 2
on the reaction cup 19. The weight 9a and the stopper
flange part 4c are so precisely worked that they can
engage with each other so tightly to cause little air
leakage.
In these embodiments as shown in Figs. 2(a)
to 2(c3, the reaction cup 19 can be effectively separated
from the suction pad 2 with energing spring when it is
placed down on a transport block, as in the embodiment
as shown in Fig. 1. In addition, these embodiments
present the advantages that the forced separation of
the reaction cup can assure a larger range of air
discharge pressures than that in the embodiment as shown
in Fig. 1, because the air discharge may be enough small,
and the pressed-down weight can prevent the air from
flowing further and consequently the reaction cup and
other parts near the suction head from being blown away.
~ The suction head as shown in Fig. 2(c) was
tested in;the same conditions as the dev1ce as shown
in Fig. 1, and the results were compared with those of
the suction head as shown in Fig. 5. The comparison
revealed~that the working stability was remarkably higher
for the embodiment as shown in Fig. 2(c), as shown in
Table 2.
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Table 2
0~ lOO reaction cups moved from the storage
to a transport block, the number of reaction
cups failed in movemen-t
Conventional suction head l to lO or
(Fig. 5) more
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This embodiment (Fig. 2(c)~
Industrial Applicability:
The suction head according to the present
invention presents the advantages that it can be
effectively used to carry reaction cups selectively in
a storage of many }eaction cups in a system using reaction
cups, and that:it can assure a stable operation of lifting
a reaction cup.
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