Note: Descriptions are shown in the official language in which they were submitted.
10~9976
This invention ~enerally relates to pipetting de-
vices which are used in microbiological, immunological and
medical laboratory research.
~ile pipetting devices and apparatus that are
adapted to simultaneously withdraw a relatively large number
Of samples ~rom individual wells of liquid samples are well
known, many priority devices are adapted to simultaneously
extract a relatively low number, i.e., a dozen or so samples
in precise predetermined quantities within the ran~e of about
25 to about 50 microliters, other devices drop si%e for meter-
ing which will extract a larger nu~ber of samples, i.e., 96
separate samples, typically have a volume capacity of only a
few microliters, particularly when the size of the array or
matrix of the total samples is relatively small. For those
types of apparatus that have a flexible diaghragm that con-
forms to the shape of a recess when vacuum pressure is applied
for the purpose of suctioning a predetermined amount of liquid
up into the suction tubes, the extremely confined and highly
dense array may preclude the mere enlarging of the recesses
; 20 for the purpose of increasing the volume of the extracted
liquid, because the enlargement may cause an overlap of the
recesses with adjacent recesses.
Accordinaly, it is an object of the present inven-
tion to provide an improved pipetting apparatus that is adapted
to suction relatively large sample volumes considering the
; high density of the samples in the array.
According to the present invention, there is provided
` an apparatus for pipetting a plurality of predetermined
quantities of a liquid, the apparatus having a collector plate
provided with a plurality of openings, the lower portion of
the ~ollector plate beina adapted to receive a plurality of
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1049976
elongated hollow collector tubes in the openings, the
op~ning communicatinq the lower surface with the upper
surface, each of said openings in said upper surface
having an enlarged generally smooth portion of a first
predetermined volume. It is further provided a manifold
plate having a recess in the lower surface thereof and an
aperture communicating the recess with the opposite side
thereof, the recess communicating fluid pressure from
the aperture to the recess. An intermediate plate is
located between the manifold plate and the collector plate
and has openings generally coextensive with the openings
in the collector plate, the openings communicating with
the recess of the manifold plate, each of the openings
having an en~arged generally smooth portion on the side
adjacent the collector plate. Each of the enlarged portions
has a second predetermined volume. A flexible impervious
diaphragm is positioned between the intermediate plate and
the collector plate and is adapted to be deflected upwardly
or downwardly within each of the enlarged portions of the
openings of the intermediate plate and collector plate,
respectively, in response to selective application of fluid
pressure thereto. A plurality of elongated hollow collector
tubes are secured to the lower side of the collector plate
within the openings. Means are provided for connecting the
manifold plate aperture to sources of positive and negative
fluid pressure for deflecting the flexible diaphragm in
opposite directions, respectively. Frame means support the
plates, the frame means being connected to at least one of
the plates.
Other objects, features and advantages will become
apparent upon reading the following detai~ed description,
in conjunction with the attached drawings. in which:
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10~9976
E'I&UE~ 1 is a side elevation of apparatus
embodyin~ the present invention;
FIGURE 2 is a top view of the apparatus shown in
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1049976
FIGURE li
FIGUE~ ~ is a cross sectional view, with portions
removed, taken generally along the line 3-3 in FIGURE 2;
FIGURE 4 is a bottom plan view of the intermediate
S plate of the apparatus shown in FIGURE 1 and particularly il-
lustrating the array or ma~rix of openings therein; and,
FIGU.RE 5 is an enlarged cross section of a portion
of the collector plate illustrating the attachment of a typical
co]lector tube to the collector plate.
Turning now to the drawings, and particularly
FIGURE 1, there is shown apparatus 10, embodying the present
invention which includes a support base 12, a vertical frame
channel member 14 which is secured to the base 12 by an angle
bracket 16 or the like. A plate assembly, indicated generally
15 at 1~, is attashed to a cross member 20 that is movable verti-
cally in the channel 14. The cross member is adjustable by a ro
`I tatabl~ knob 24 that is connected to a pinion gear (not shown~
that xides in a rack (not shown) within the channel 14. The
rack and pinion geax arrangement enables the cross member ~0 and
plate assembly 18 to he raised and lowered to the desired e]eva-
tion as is nececsaxy to extract and deposit liquid samples. The
` plate assemhly 18 has a fle~ible tube 28 conr.ected thereto, with
its opposite end connected to a valve means 30 which is sl~own to
be a two-way solenoia valve that is actuated by an electrical
switch 32. The solenoid valve has a common nozzle 34 to which
the flexible tube 28 is connected and a~ternatively communicates
the common nozzle 34 with nozzles 36 and 38 which are adapted
to be connected to sources of vacuum and positive pressure,
respectively. The plate assembly 18 has a plurality of col-
lector tubes 40 extending downwardly from the underside thereof -
for insertion into wells from which samples are to be taken.
The tub~s 40 are preferably about three inches along and fabri-
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1049~76
cated from stainless steel.
Turning to an important aspect of the present inven-
tion and referring to FIGURE 3 which is a cross section taken
generally along the line 3-3 in FIGURE 2, the plate assembly
18 comprises a manifold plate 42, a collector plate 44 into
which the collector tubes 40 are secured and an intermediate
plate 46 which is located between the manifold plate and the
collector plate. A~flexible diaphragm 48 is positioned be-
tween the intermediate and collector plates for reasons which
will be hereinafter described. Referring also to FIGURE 5
the collector plate 44 has a plurality of openings 50 extend-
ing therethrough, with the underside portions 52 of the open-
ings being of increased diameter and terminating in an annular
shoulder 54. The collector tubes 40 have an outside diameter
that is slightly greater, i.e., a few thousandths of an inch
than the inside diameter of the enlarged portion ~54 so that
when they are inserted therein, they are compressed slightly
to provide a snug, secure fit. Moreover, the inside diameter
of the collector tubes 40 is preferably approximately equal to
the diameter of the openings 50 adjacent thereto as shown in
FIGURE 5. Near the upper side of the collector plate 44~ the
openings 50 are enlarged into a generally smooth~ preferably
hemispherical shaped portion 56~ as shown in FIGURES 4 and 5.
The size of the enlarged portion 56 is preferably predetermined
so that when the diaphragm is displaced into contact with the
surface of the hemispherical portion 56~ the volume displaced
is of a precise predetermined amount.
The intermediateplate 46 also has a plurality of
openings 58 that are coextensive with the openings 50 and
which also have an enlarged portion 60 that is preferably simi-
larly hemispherically shaped and of predetermined size. The
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manifold plate 42 has a large recessed portion 62 in the lower
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104997~
si.de ther~o whlch is coextellsive with all of the openings 58
in the intermediate ~l~te. ~n ~perture 64 communicates the
por~ion 62 with a ccnn~ctor nozzl~ 66 (see FIGUR~ 1) to which
the flexible conduit or t~ing 28 Ls attached. '~hu~, positive
S or negative pressure that is present withi.n the tubiny 2~ is
communicated to the recessed portion 62 through the aperture
64. Since the openings 58 in the inter~,edi.ate plate are in
communication with the recessed portion 62 of the manifold
,plate, the ~osit~ve and negative pressure i.~ appl.ied to the
lG flexible diaphragm 48 during operati.on. A seal 68 may be pro-
vided around the periphery of the recessed portiGn between the
intermediate and manifold plates to prevent leakage.
To transfer samples from receptacle to a plurali.ty
of cul.ture wells, the receptacle having the culture material
~5 therein is placed below the plate assembly 18 on the base 12
and the switch 32 is placed in the positi.oIl whereby positi.ve
pressure is applied thr.ough the noæ21e ~R and flexible cond
28 so that ~hepositive pressure deflects the diaphragm 48
downwardly into the hemispherical portions 56~ The knob 24 is
then rotated so that the assembly 18 is lo~.~ered to immerse the
ends of the tubes 40 into the liquid in the wells having the
culture material therein. The switch 32 is then moved to the
position whereby vacuum is communicated to the col~mon conduit
28 and the diaphragm 48 is deflected upwardly into contact wlth
the walls of ~he enlarged portion 60 of t,h~ ~ntermediate plate.
By moving the impervious diaphragm 48 from the lower to the
upper position, the liquid is suctioned upwardly into the col-
, lector tubes 40. To transfer the liquid -from the collector
., ' tubes to another device~ the knob 24 is rotated to rai.se tlle
assembly 18 so that another tray can be pl.aced beneath the col-
lector tubes and the assen~ly can then b~ manipulated to the
proper elevation whereupon the switch 32 can then be moved to
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apply positive pressure to thereby force the liquid from the
tube~s to the desired locations.
In keeping with the present invention, while the
manifold plate 42 is preferably securely attached to the cross
support 20, the intermediate and col'ector plates are prefer-
ably releasably secured to the manifold plate. To hold the
plates together, four threaded screws 70 are positioned at the
four corner portions of the manifold plate outside of the outer
periphery of the recessed portion 62. The threaded screws 70
pass through larger diameter, non-interfering apertures 72 in
the manifold and intermediate plates, respectively, and e..yage
a threaded aperture in the collector plate. By tightenin~ the
screws 70, the collector plate will be drawn upwardly so as to
~mpress the diaphragm 48 in sealing engagement and to tighten
the manifold, intermediate, and collector plates together.
Conversely, by loosening the screws 70, the collector plate
with the tubes sécured thereto can be remo~ed for cleaning ahd
the intermediate plates 46 can also be removed for similax
reasons.
In accordance with an important aspect of the present
invention, the size of the enlarged port-ons 55 and 60 deter
mine the volurne that is extracted by the pipetting apparatus
~Id, if the volurne traversed by the diaphrag~l in each of the
hemispherical portions 56 and 60 of the plates is 50 microliters,
for example, the application of positive and negative pressure
in the manner as previously described will extract a s&mple
volu~.e of about 100 microliters. In the event that some pre-
cise quantity other than 100 microliters is desired to be ex-
tracted, a separate intermediate plate 46 having nemispherical
portions 60 which are of some other volurne than the 50 micro-
; liters, i.e., about 25 microliters, for example, may be sub-
stituted. Thus, by going through the operatin~ stéps previously
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described, a total of 75 microliters may b~ extracted, since
the mov~m~nt of the diaphragm from ~he io~er openinq 56 to the
rest position snowrl in FIGUP~ 3 would e~fectively suction 50
microliters and the movement to the upper surf~ce of the hemis-
S pherical portion 60 would suction an additional 25 microli-ters.
It should also be understood that 25 microliters may be ex-
tracted by merely inserting the tubes in the well containing
the cultures to be sampled withou~ applying positive pressure
to deflect the membrane downwardly. In other words, the appli-
cation of vacuum pressure would merely move the diaphra.3m 48 fromthe position shownin FIGURE 3 upwardly into contact with the
hemispherical portions 60 which would effectively suction only
25 microliters.
As is sho-~n in FIGURE 4, the matrix or array of open-
ings 58 in the intermediate plate 46 form a rectilinear matrixor array which comprises 12 rows, each of which have a total
of 8 openings for a total of 96 places or locatio~Js. Sin~e --
the cultural trays in which the sample cultures are developed
are becoming increasingly standardized, it is preferred that
the size o~ the matrix or array of collector tubes be compatible
with the location of the individual culture wells in such trays.
Thus, it is preferred that the array of collector tubes 40 fit
within the dimensions of about 2.5 to about 4 inches. Thus,
the adjacent openings 58 will be spaced apart approximately
0.3~5 inches from center to cer.ter. The enlarged por~ions 56
of the collector plate as previously mentioned, are preferably
hemispherical in shape and may have the dimensions. of about
0.125 inches in depth with a xadius of about 0.1875 inches.
~ith such dimensions, adjacent enlarged portions 56 do not merge
with one another as is des.red.
It should also be understood that the sources of
vacuum and positive pressure are typically present in most lab-
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10~9976oratories and the appar~tus embodying the present invention is
compatible with ~ypical laboratory vacuum and positive pres-
sures of about 15 pounds per square inch so that flexible
tubing can be used for interconnecting the nozzles 36 and 38
S with the laboratory supplies.
The use of the snug fitting of the collector tubes
40 into the increased diame~er lower portion 52 of the openings
50 which terminates in the annular shelf ~2 has a quality ccn- :
trol advantage during fabricat;.on in that the tubes can be in-
serted to a unifonm depth since the ends of the tubes cannot
penetrate inwardly beyond the annular shelf 54.and therefore
cannot penetrate into the hemispherical portion 56. If ~he
ends of the tubes could enter the portion 56, they could cut
: the diaphragm when it is defle.cted dowrlwardly upon application
of positive pressure. Thus, the use of ~he annular shelf pre-
; vents the ends of the inserted collector tubes from cutting
the ~i.aphrasm and also provides a reliable and ~niform depth
of insertion of the tubes within the collector pl2te during
fabrication.
io Whlle various embodiments of the present invention
,`3 have been shown and described, various modifications, substi-
tutions and alternatives will be suggested to those skilled .in
. the art. Accordingly, the scope of the protection ~o be
afforded this invention should not be limited by the particular
embodiments shown and described, but should be determined in
: tern~ of the definitions of the invention as set forth ir. the
appended claims and equivalents thereof.
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