Multiple pipette samples

A pipette sampling device for removing and transferring a plurality of liquid samples consists of an improved structure which allows a low cost manufacturing process, the use of a minimum amount of material in such process, and a pipette cavity shaped such that hydraulic principles insure accuracy during filling and dispensing. The pipette sampling device is positionable within a filling tray which permits an initial filling of the pipettes by a liquid through capillary action, and an actuating device is then attached over the pipettes. The actuating device provides a vacuum so that the liquid is drawn into each pipette cavity until the walls and rims of all of the cavities are completely wetted and a stretched meniscus is formed at the top of each cavity. The actuator may then be utilized to effect the dispensing of the liquid in each pipette cavity through a provided pressure. To accomplish this process, the sampling device is constructed to include a manifold which is designed as an inflexible, rigid monocoque structure.

BACKGROUND OF THE INVENTION 
1. Background of the Invention 
The present invention relates to the field of fluid handling, and more 
particularly pertains to an improved multiple pipette sampler system and 
related apparatus. 
2. Description of the Prior Art 
Pipettes of various configurations for withdrawing measured liquid samples 
from one container and transferring them to a second container have long 
been in use and are recognized as prior art. Typically, these pipettes 
require time-consuming care in achieving accurate measurement, and in 
their cleaning or sterilization between respective uses. Inaccuracies in 
measurements stem from lack of positive control of the shape and position 
of the liquid at the top and tip of the pipette at the time of filling, 
and also from variations in the amount of liquid left in the pipette tip 
upon expelling. Attempts to control these inaccuracies have in the past 
taken the form of costly manufacturing methods and the use of additional 
parts to control the filled liquid position, as well as the use of 
elaborate apparatuses to encourage uniform dispensing. 
Advances in microbiological, immunological, and other statistical research 
methods have made individual sampling impractical in terms of time and 
cost. The requirement for large numbers of samplings of contaminating 
liquids has created a need for low cost, disposable, multiple pipette 
samplers. The prior art reveals a number of devices which represent 
attempts to solve the above-identified problems, and several multiple 
sample pipette assemblies are also in existence. Some of these devices are 
shown in U.S. Pat. Nos. 3,261,208, 3,568,735, 4,158,035, 4,461,328 and 
4,468,974. A review of these patents will reveal that the attempts to 
provide accurate, multiple samples involve increased precision, materials, 
of numbers of parts--all of which add to the manufacturing cost and 
complexities. As such, it can be appreciated that the prior art attempts 
to control the uniformity of operation have resulted in awkward and 
time-consuming procedures and hardware. 
As such, it appears that there is a continuing need for a multiple pipette 
sampler system which provides for a fast, convenient transfer of multiple 
liquid samples in repetitive situations wherein the construction thereof 
permits accurate sampling and minimum manufacturing cost, preferably in a 
disposable unit. In this respect, the present invention substantially 
fulfills this need. 
SUMMARY OF THE INVENTION 
In view of the foregoing disadvantages inherent in the known types of 
multiple pipette sampler systems now present in the prior art, the present 
invention provides an improved multiple pipette sampler system which 
permits an extremely accurate measuring of the quantity of liquid drawn 
into and dispensed from a plurality of pipette cavities. As such, the 
general purpose of the present invention, which will be described 
subsequently in greater detail, is to provide a new and improved multiple 
pipette sampler which has all the advantages of the prior art multiple 
pipette samplers and none of the disadvantages. 
To attain this and in order to take multiple uniform samples, identical 
pipette cavities are formed in a thin (0.008 to 0.040 inches) plastic 
sheet. A second thin plastic sheet is formed so that when joined to the 
first sheet, a manifold is created whereby equal pressure may be applied 
to each pipette cavity. At the same time, the joining of the first and 
second sheets produces a rigid monocoque structure which holds the pipette 
cavities in a single plane. 
In order to obtain uniform initial conditions, a preformed plastic filling 
tray may be provided so that the level of the liquid sample is identical 
for each use. When placed in this filling tray, each pipette tip draws in 
an equal volume of liquid due to capillary action. 
A quick release connection is provided in the plastic manifold, whereby a 
small actuating device is attached to the pipette assembly and is operable 
as a source of vacuum or pressure. When the actuating device is operated, 
i.e., when it is utilized to draw a vacuum on the manifold, liquid is 
drawn into the pipette cavities until they are overfilled to a point where 
the cavity walls are completely wetted and a convex, stretched meniscus is 
formed at the top of each cavity. Since the force required to produce this 
stretched meniscus is large compared to irregularities, such as the 
levelness of the pipette array or differences in the surface conditions of 
the plastic, these overfilled liquid volumes are nearly identical. When 
the actuator is released to a preset stop, identical concave meniscuses 
are formed in each cavity with equal volumes of liquid then being retained 
therein. The pipette cavities are formed in the shape of the upper one 
half of an hourglass which reduces the size of the tips to small capillary 
tubes upon which no liquid drops are formed when the pipettes are 
withdrawn from the liquid in the filling tray. Each pipette cavity now 
holds an equal volume of liquid sample. 
The multiple pipette sampler comprising the invention is then transferred 
to receiving wells, the actuator is released, and the liquid samples are 
expelled. The pipette tips are placed so that they are below the liquid 
level in the receiving wells and, when they are withdrawn, capillary 
action removes all but a small, uniform volume of liquid from each pipette 
tip. 
Since the actuating device is attached to the multiple pipette array during 
use, whereby it comprises a single unit in combination with the array, the 
complete device is fully mobile, and is operable to quickly and easily 
transfer liquid samples in a one-hand operation. After use, the 
contaminated pipette array and filling tray are discarded, while the 
actuator is retained for further use. 
There has thus been outlined, rather broadly, the more important features 
of the invention in order that the detailed description thereof that 
follows may be better understood, and in order that the present 
contribution to the art may be better appreciated. There are, of course, 
additional features of the invention that will be described hereinafter 
and which will form the subject matter of the claims appended hereto. 
Those skilled in the art will appreciate that the conception, upon which 
this disclosure is based, may readily be utilized as a basis for the 
designing of other structures, methods and systems for carrying out the 
several purposes of the present invention. It is important, therefore, 
that the claims be regarded as including such equivalent constructions 
insofar as they do not depart from the spirit and scope of the present 
invention. 
Further, the purpose of the foregoing abstract is to enable the U.S. Patent 
and Trademark Office and the public generally, and especially the 
scientists, engineers and practitioners in the art who are not familiar 
with patent or legal terms or phraseology, to determine quickly from a 
cursory inspection the nature and essence of the technical disclosure of 
the application. The abstract is neither intended to define the invention 
of the application, which is measured by the claims, nor is it intended to 
be limiting as to the scope of the invention in any way. 
It is therefore an object of the present invention to provide a new and 
improved multiple pipette sampler assembly which has all the advantages of 
the prior art multiple pipette sampler assemblies and none of the 
disadvantages. 
It is another object of the present invention to provide a new and improved 
multiple pipette sampler assembly which may be easily and efficiently 
manufactured and marketed. 
It is a further object of the present invention to provide a new and 
improved multiple pipette sampler assembly which is of a durable and 
reliable construction. 
An even further object of the present invention is to provide a new and 
improved multiple pipette sampler assembly which is susceptible of a low 
cost of manufacture with regard to both materials and labor, and which 
accordingly is then susceptible of low prices of sale to the consuming 
public, thereby making such multiple pipette sampler assemblies 
economically available to the buying public. 
Still yet another object of the present invention is to provide a new and 
improved multiple pipette sampler assembly which provides in the 
apparatuses and methods of the prior art some of the advantages thereof, 
while simultaneously overcoming some of the disadvantages normally 
associated therewith. 
Still another object of the present invention is to provide a new and 
improved multiple pipette sampler assembly which facilitates an extremely 
accurate measuring of liquid samples contained in each of a plurality of 
pipette cavities. 
These together with other objects of the invention, along with the various 
features of novelty which characterize the invention, are pointed out with 
particularity in the claims annexed to and forming a part of this 
disclosure. For a better understanding of the invention, its operating 
advantages and the specific objects attained by its uses, reference should 
be had to the accompanying drawings and descriptive matter in which there 
is illustrated preferred embodiments of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
With reference now to the drawings, and in particular to FIGS. 1 through 12 
thereof, a new and improved multiple pipette sampler embodying the 
principles and concepts of the present invention will be described. 
As described herein, the multiple pipette sampler device is used to 
simultaneously rehydrate and innoculate a 96 well microtiter tray. Thus, 
the pipette sheet 12, as illustrated in FIGS. 1 and 2, is an array of 96 
pipette cavities 14 depending downwardly from an integral flat sheet 16. A 
precision die is used to thermoform a 0.015 to 0.020 inch 
polyvinylchloride (PVC) plastic sheet so that each cavity 14 is identical. 
The tip of each pipette cavity 14 is removed so that a liquid may be drawn 
into the cavity. 
In a similar manner, the housing 18, as shown in FIGS. 3 and 4, is 
thermoformed in a second die from a 0.015 to 0.020 inch polyvinylchloride 
plastic sheet. The concavely-shaped housing 18 includes a skirt portion 20 
and an interiorly formed step 22. Vent passages 24 are formed at each 
corner of the housing 18, and a plurality of stiffening depressions 26 are 
thermoformed in a top surface 28 of the housing. As best illustrated in 
FIG. 3, an actuator attachment 30, which will be subsequently described in 
greater detail, is also integrally formed or otherwise separately attached 
to the top surface 28 of the housing 18. 
The pipette sheet 12 and the housing 18 are joined together, preferably by 
dielectric heat sealing, into a rigid structure 32 as shown in FIG. 5. In 
this regard, the pipette sheet 12 and the housing 18 are sealed along a 
peripheral edge generally designated by the reference numeral 34. This 
sealing effectively forms a manifold 36, and each of the stiffening 
depressions 26 are heat welded at bottom sections 38 thereof to the 
pipette sheet 12, thus to form a beam structure clearly illustrated in the 
cross-sectional view of FIG. 5. As such, each pipette cavity 14 may have 
equal vacuum or pressure applied to it, and each such cavity is held in a 
rigid plane during such pressure variations. 
With further reference to the aforementioned actuator attachment 30, as 
best illustrated in FIGS. 3 and 8, it can be seen that the same consists 
of a 0.030 inch thick plastic washer which is sealed or otherwise affixed 
to the housing 18, preferably in a preformed cavity 40. A 
through-extending aperture or passage 42 is provided into the manifold 36 
of the assembly. The washer 30 serves as a sealing surface for a gasket 44 
and as purchase for grasping hooks 46 which join an actuator device 48 to 
the pipetting device 32, thus to form a single portable unit. 
A filling tray 50, as shown in FIGS. 6 and 7, is thermoformed in a die from 
a 0.015 to 0.020 inch plastic sheet. The integral construction of the tray 
50 includes vents 52 at the four corners thereof. Additionally, a 
plurality of liquid holding slots 54 are formed in the tray 50, with these 
slots being designed to retain a liquid to be drawn into the pipette 
cavities 14 in a manner yet to be described. 
With further reference to the actuator device 48, reference is again made 
to FIG. 8 of the drawings for a complete description thereof. In this 
respect, it can be seen that the actuator device 48 includes a housing 56, 
with the aforementioned grasping hooks 46 being pivotally mounted within 
the housing. The hooks 46 are provided with upwardly extending, manually 
movable handles 58, thus to provide for their rapid attachment to and 
release from the actuator attachment 30. A pressure chamber or cylinder 60 
is formed within the housing 56 and includes a reciprocably movable piston 
62 mounted therein. The piston 62 is provided with a sealing gasket 64 so 
as to prevent airflow around the peripheral edges of the piston. A topmost 
portion of the piston 62 is attached to a manually operable handle 66 
which thus facilitates the upward or downward movement of the piston 
within the chamber 60. 
A manually operable, spring-biased filled position catch 68 is reciprocally 
mounted within the housing 56. The catch 68 includes an extended end 
portion 70 that includes a cammed surface which slides over an extended 
edge 72 of the handle 66. The extended edge 72 of the handle 66 is also 
cammed so that a slidable engagement between the edges 70, 72 is 
facilitated during an upward movement of the handle 66. After the edge 72 
moves past the edge 70, the spring 74 moves the edge 70 beneath the edge 
72, thus to maintain the piston 62 in its upwardly directed position. 
The actuator device 48 further includes limit stops 76, 78. More 
specifically, the limit stop 76 comprises a threaded member which may be 
moved upwardly or downwardly within the handle 66 and is operable to limit 
the amount of upward movement of the handle relative to the housing 56. In 
effect, the limit stop 76 comprises an overfill limit stop inasmuch as it 
can be adjusted to a point where the pipette cavities 14 are precisely 
filled by an upward movement of the piston 16. 
Similarly, the limit stop 78 comprises a threaded member which may be 
adjusted upwardly or downwardly relative to the housing 56, with this stop 
comprising a liquid expelling limit stop, whereby a precise dispensing of 
liquid from the cavities can be achieved by a downward movement of the 
piston 62 until an abutable relationship between the handle 66 and the 
limit stop 78 is experienced. The limit stop 78 is abutable with an 
extended handle portion 80, while the overfill limit stop is abutable with 
an extended housing portion 82. 
OPERATION 
In operation, a premeasured volume of innoculating liquid 84, such as shown 
in FIGS. 9, 10, 11 and 12, is placed in the filling tray 50 illustrated in 
FIGS. 6 and 7. The pipetting device 32 is then lowered into the filling 
tray 50, and the pipette tips are filled to equal levels by capillary 
action as shown in FIG. 9. The actuating device 48, as best illustrated in 
FIG. 8, is then attached and sealed to the pipetting device 32 by means of 
the grasping hooks 46 being hooked over the edges of the washer 30. When 
the piston 62 is drawn upwardly within the housing 56, a vacuum is formed 
within the lower portion of the pressure chamber 60. As the piston 62 is 
drawn upwardly until the overflow limit stop 76 abuts with the extended 
housing edge 82, the innoculating liquid 84 is drawn into each pipette 
cavity 14 until the walls and rims of all such cavities are completely 
wetted and a stretched meniscus 86 is formed at the top of each cavity as 
shown in FIG. 10. 
Since the vacuum required to form a meniscus 86 is relatively large, each 
meniscus serves to limit and equalize the liquid volumes held in the 
pipette cavities 14 at this overflow condition, despite small variations 
due to levelness of the tray 50, impurities, or the wetting of the plastic 
walls. A manual release of the piston handle 66 will allow the piston 62 
to travel partially downwardly within the cylinder 60 until the extended 
edge 72 engages the edge 70 forming a part of the filled position catch 
68. The piston 62 is then locked in this position, while the partial 
downward movement of the piston 62 results in at least a partial release 
of vacuum within the manifold 36. As such, predetermined equal liquid 
volumes are retained in all of the pipette cavities 14, as best 
illustrated in FIG. 11. At this point, each pipette cavity rim 88 is 
uniformly wetted, and the meniscus 86 again tends to equalize the liquid 
volumes. 
The complete unit consisting of the actuating device 48 and the pipetting 
device 32 is then removed from the filling tray 50 and transferred to an 
unillustrated 96 well microtiter tray. The housing skirt 20 and the 
associated step 22, as best illustrated in FIG. 4, position the pipette 
tips 90 in the receiving wells. The filled position catch 68 may then be 
manually pulled from the housing 56, thereby to effect a disengagement of 
the edges 70, 72 so as to release the piston 62 for further downward 
movement within the cylinder 60. The piston 62 then returns to its 
original position, and most of the innoculating liquid 84 is expelled from 
the pipette cavities 14. The pipette tips 90 have been positioned so that 
at this time, they are below the level of liquid 84 in the microtiter tray 
wells. The complete unit is then removed from the microtiter tray and 
surface tension draws the liquid volume in each tip 90 down to an equal 
level, as illustrated in FIG. 12, thereby to ensure that equal liquid 
volumes have been delivered to the microtiter tray wells. In this regard, 
the liquid volumes in each tip 90 at the start and finish of the cycle are 
equal, i.e., the same amount of liquid is retained in the procedural steps 
represented by FIGS. 9 and 12. Accordingly, the pressure in the pipette 
cavities 14 is then at atmospheric at the completion of the cycle, and no 
single pipette tip 90 is fully emptied of the liquid 84. 
The complete unit is then returned to the filling tray 50, the actuating 
device 48 is removed, and the contaminated pipetting device 32 and the 
filling tray, as well as all the remaining innoculating liquid 84, are 
discarded. 
With respect to the above description then, it is to be realized that the 
optimum dimensional relationships for the parts of the invention, to 
include variations in size, materials, shape, form, function and manner of 
operation, assembly and use, are deemed readily apparent and obvious to 
one skilled in the art, and all equivalent relationships to those 
illustrated in the drawings and described in the specification are 
intended to be encompassed by the present invention. 
Therefore, the foregoing is considered as illustrative only of the 
principles of the invention. Further, since numerous modifications and 
changes will readily occur to those skilled in the art, it is not desired 
to limit the invention to the exact construction and operation shown and 
described, and accordingly, all suitable modifications and equivalents may 
be resorted to, falling within the scope of the invention.