U.S. patent number 3,645,506 [Application Number 04/846,040] was granted by the patent office on 1972-02-29 for sampling supply device having magnetic mixing.
This patent grant is currently assigned to Micro-Metric Instrument Co.. Invention is credited to William Selesnick.
United States Patent |
3,645,506 |
Selesnick |
February 29, 1972 |
SAMPLING SUPPLY DEVICE HAVING MAGNETIC MIXING
Abstract
Process and apparatus adapted to supply sequentially a series of
samples, normally liquid, at a sampling station for further
processing such as by a conventional analyzer, wherein the samples
are stirred or agitated magnetically to maintain them substantially
in a homogenous condition. For this purpose, minute dipolar magnets
are freely contained in the samples, and the supply device contains
recovery means for recapturing the magnets after the samples have
passed the sampling station. Dipolar master magnets are passed
relatively to the freely-held magnets to induce their rotation. In
a preferred form, a turntable carries the master magnets, and belt
drive means jointly supports and rotates the turntable.
Inventors: |
Selesnick; William (Shaker
Heights, OH) |
Assignee: |
Micro-Metric Instrument Co.
(Valley View, OH)
|
Family
ID: |
25296777 |
Appl.
No.: |
04/846,040 |
Filed: |
July 30, 1969 |
Current U.S.
Class: |
366/273 |
Current CPC
Class: |
B01F
13/0818 (20130101) |
Current International
Class: |
B01F
13/08 (20060101); B01F 13/00 (20060101); B01f
009/10 () |
Field of
Search: |
;259/63,65,66,67,102,103,107,108,13,58 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Jenkins; Robert W.
Claims
I claim:
1. Stirring or agitating apparatus including a container adapted to
hold material to be stirred or agitated, a first dipolar magnet
freely held within said container for independent movement to
provide a stirring action by such movement of the magnet itself, a
plurality of second dipolar magnets supported seriatim and in fixed
relationship to each other along a path, and means to move the
container and said path of second dipolar magnets relatively to
each other, so that the poles of said first dipolar magnet are
magnetically coupled to the poles of successive ones of the second
dipolar magnets along said path to induce said movement of the
first dipolar magnet within the container.
2. The apparatus of claim 1 wherein said container is stationary,
and said second dipolar magnets are so supported along said path to
move the opposite poles thereof in tandem along said path
successively to attract and repulse the poles of said first dipolar
magnet and induce a rotary movement thereof.
3. The apparatus of claim 1 wherein said container is stationary,
and said second dipolar magnets are so supported along said path to
move like poles thereof in tandem along said path successively to
attract the pole of said first dipolar magnet that is opposite to
said like poles and induce a reciprocable movement thereof.
4. The apparatus of claim 1 wherein a plurality of said containers,
each freely holding a first dipolar magnet, are arranged in
essentially a circle, said plurality of said second dipolar magnets
is carried on a periphery of a rotatable turntable mounted for
rotation essentially concentric with and adjacent to said circle of
containers, and said means to move the containers and second
dipolar magnets relatively to each other rotates the turntable.
5. The apparatus of claim 1 wherein said first dipolar magnet is
plastic-coated to minimize inadvertent adherence to said
container.
6. A process for stirring material within a container comprising
placing a first dipolar magnet in said container for free,
unimpeded movement therein, successively passing a plurality of
second dipolar magnets relatively past the container, successively
magnetically attracting the poles of said first dipolar magnet by
the relative passing of the poles of said second dipolar magnets to
induce movement of said first dipolar magnet within the container
and thereby impart a stirring movement to said material.
7. The process of claim 6 wherein like poles of said plurality of
second dipolar magnets are moved in tandem along said path
successively to attract the pole of said first dipolar magnet that
is opposite to said like poles and induce a reciprocable movement
thereof.
8. The process of claim 6 wherein alternately arranged north and
south magnetic poles of said plurality of second dipolar magnets
are moved along said path successively to attract and repulse the
poles of said first dipolar magnet and induce a rotary movement
thereof.
9. The process of claim 6 wherein a plurality of said containers is
arranged along a predetermined path, each container having a first
dipolar magnet, and said plurality of second dipolar magnets is
moved along said path.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a process and apparatus for
presenting seriatim a series of samples at a sampling station for
further processing, such as testing, analyzing, or the like, and
more particularly to such process and apparatus wherein the samples
are magnetically stirred to maintain them in a homogenous state so
that representative portions may be withdrawn.
In many instances, such as in testing procedures, it is the
practice to process a plurality of individual samples, usually of
relatively small volume, by automatically advancing the samples in
succession, as on an indexing table, to a sampling station. A
portion from each individual samples is then aspirated or otherwise
removed and further processed as may be desired. For example, as
one instance, continuous determinations of the residue of an
insecticide or pesticide in plant material may be made utilizing a
cholinesterase bioassay procedure. Also such sequential sampling
from a series of containers may be made to measure the photometric
properties of samples.
One especially popular use of this general sampling technique
occurs in hospitals, clinics and laboratories where samples of body
fluids are analyzed for diagnostically significant factors, such as
urea, sugar, etc. In particular, blood samples are often analyzed
and tested by sequentially feeding portions of such samples to
known analyzing apparatus. For instance, exemplary sampling supply
apparatus of the type mentioned is disclosed in U.S. Pat. No.
3,038,340 to Israeli and U.S. Pat. No. 3,251,229 to Isreeli et
al.
Regardless of the particular purpose for which the samples may be
tested or analyzed, a common problem arises in that a
representative portion must be drawn from each sample in order to
obtain reliable, reproducible results. In the case of certain
liquids which may contain matter that tends to settle, it is
necessary or desirable to stir the liquid before or even while the
liquid sample is being removed from cups or other containers at the
sampling station. Particularly in the case of clinical analysis of
blood hemoglobin, determinations are made on whole blood specimens
which must be well mixed and in a homogenous condition when
aspirated or otherwise withdrawn from the sample container for
transmission to analysis apparatus. If left unattended, blood and
blood serum samples can separate into plasma and red blood
cells.
Various techniques have been suggested for stirring samples while
still within their containers, so that the samples are in an
homogenous condition at the time of their removal at the sampling
station. For example, U.S. Pat. No. 3,107,536 to Ferrari discloses
a stirrer comprising a metal spindle fitted within a polyethlene
tube and rotated by a miniature electric motor. U.S. Pat. Nos.
3,107,537 and 3,230,766 both to Isreeli et al. teach the use of
vibratory stirring means actuated by an electric solenoid and
movable as a unit with the liquid-withdrawing device into and out
of the containers of the samples at the sampling position. U.S.
Pat. No. 3,252,327 to Ferrari discloses introducing air into liquid
samples in containers during the sampling operation and also
immediately before such operation to stir the liquids and prevent
settling of particulate matter which may be suspended in the
liquid.
All of these techniques are relatively cumbersome and unduly
complicate the sampling apparatus. More significantly, in some
cases the insertion of the same element, such as a stirrer, in all
of the samples tends to introduce cross-contamination and leads to
inaccurate test results. It would therefore advance the art if
relatively simple stirring or agitating means could be effected
which also acted individually and only for each container or sample
so as to minimize the risk of contamination.
SUMMARY OF THE INVENTION
In accordance with the present invention, samples are maintained in
essentially homogenous condition by stirring that is induced
magnetically. In one form, a rotary plate such as an indexing
table, carries a series of containers of different samples in
spaced relation along its periphery and advances the samples,
seriatim, to a station equipped with sampling or takeoff means.
Each container or cup freely holds a minute, subservient dipolar
magnet. One or more master or controlling dipolar magnets are
mounted to move relatively to the cups, such that the repeated
attraction and repulsion between the respective poles of the two
dipolar magnets, as they pass relatively to each other, causes the
freely held magnets to turn within the containers and thereby stir
or agitate the material contained therein. The turning or rotation
of the freely held magnets is preferably unidirectional, although
it can also be reciprocable.
The present process and apparatus also include recovery of the
minute or subservient magnet from each cup after a sample has been
withdrawn. Preferably, this is accomplished simultaneously with the
drawing of a sample from an adjacent but succeeding cup, so that
the samples are not contaminated by the magnet recovering means
before a portion is taken. In a preferred form, the recovery means
includes an additional magnet mounted to move substantially in
unison with a sampling device or tube when it moves toward the
rotary-plate-carrying sample cups and to the sampling position.
Thus, at the same time a portion of one sample is withdrawn, the
recovery magnet probes in a preceding, already tested sample and
magnetically attracts and holds its subservient magnet. Further,
when the recovery magnet returns with the sampling device to an
original position away from the rotary plate, the minute or
subservient magnet is automatically removed from the recovery
magnet and collected with other like magnets for reuse.
The present invention further includes a novel drive arrangement
for moving the master magnets relatively to the subservient
magnets. In a preferred form, a turntable carrying the master
magnets has an arcuate drive element. A plurality of pulley members
are mounted for rotation essentially tangent to the arcuate path
transcribed by translation of the drive element upon rotation of
the turntable. A belt drive means is trained between and engages
the pulley members and the arcuate drive element, so that, in
motion, the belt drive means supports as well as rotates the
turntable.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings illustrate a presently preferred
embodiment wherein:
FIG. 1 is a plan view of one embodiment of the invention with parts
broken away for purposes of illustration;
FIG. 2 is an offset section of FIG. 1 on the line 2--2;
FIGS. 3 through 9 are schematic, sequential views and illustrate
diagrammatically one type of interreaction between master and
subservient magnets to induce unidirectional rotation of the
latter;
FIGS. 10 through 15 are schematic, sequential views and illustrate
diagrammatically another type of interreaction between master and
subservient magnets to induce reciprocable rotation of the
latter;
FIGS. 16 through 18 are sequential, fragmentary side elevations of
means for recovering a subservient magnet from a cup or container
and show the joint action of the recovery means with a sampling
device;
FIGS. 19 and 20 are sections on the lines 19--19 and 20--20 of
FIGS. 17 and 18, respectively; and
FIGS. 21 and 22 are enlarged perspective views of the recapturing
and sampling means of FIGS. 16 through 18.
DESCRIPTION OF THE PREFERRED EMBODIMENT
A presently preferred embodiment comprises as principal components
a rotary plate with sample cups and attendant parts, generally
indicated at A (FIG. 1); a mounting and drive arrangement for
master magnets generally represented at B; and magnet-recovering
means shown in conjunction with a sampling device and generally
represented at C. The structure of these components and their
manner of joint operation are as follows:
STRUCTURE
Referring initially to FIGS. 1 and 2, a sample supply device
comprises a housing 10 of substantially triangular configuration in
plan, a sample-containing plate 11 being mounted for rotation at
the narrower end of the housing, and sampling and magnetic-recovery
means, together with their attendant operating parts, being carried
within the larger end. More particularly, plate 11 has a central
dish-shaped portion 12 and an outer radial flange 13. The plate 11
is preferably made from nonmagnetic materials such as synthetic
plastics like polymethacrylate resins or light metals like
aluminum. The dish-shaped portion 12 has an upstanding boss 14
loosely fitted around a vertically disposed shaft 15 and seated
upon a flanged collar 16 fixed to the shaft. The shaft 15 extends
through an oversized opening in an underslung cover plate 17
riveted to the housing 10. The periphery of the flange of collar 16
has one or more holes to receive a fixed pin 18. The plate 11 has a
series of holes 20 overlying and freely receiving the pin 18, so as
to provide a driving connection with the shaft 15. Because of the
loose fit between the boss 14 and shaft 15 and between openings 20
and pins 18, the rotary plate 11 can be easily removed from the
shaft 15 or positioned thereover with a shaft-driving connection in
any desired rotary position of the plate. The indexing means for
periodically turning the shaft 15 through a desired angle and
thereby presenting samples seriatim at a sampling device C does not
form part of the present invention and is therefore not described
in detail. Such indexing means are well known in the art. For
example, the indexing means described in U.S. Pat. No. 3,230,776 to
Isreeli et al. may be used.
The outer radial flange 13 of plate 11 has a plurality of slots 21
which gradually widen in an outward radial direction adjustably to
receive cups or crucibles 22 having rims 23 which seat on the sides
of the slots 21. In accordance with the present invention, each cup
22 has at least one minute, dipolar magnet 24 which acts
subserviently to a controlling master magnet hereinafter described.
The magnets 24 are rod-shaped and quite small, measuring about 0.25
inch in length for use in cups about 0.50 to 0.75 inch in diameter
and preferably have a plastic coat, such as
polytetrafluoroethylene, to minimize inadvertent adherence to a cup
22.
In order to induce magnetic rotation of the minute magnets 24, one
or more controlling or master magnets are passed relatively to the
former, the motion of the controlling magnets being independent of
the motion of the rotary plate 11. In the embodiment illustrated,
an annular turntable 25, disposed concentrically about the
dish-shaped portion 12 of the rotary plate, carries a plurality of
permanent dipolar master magnets 26 which are spaced
circumferentially along the edge of the turntable 25 with their
north-south poles alternately arranged. However, the master magnets
can be otherwise arranged and still induce rotation of the
subservient magnets. For example, as hereinafter described, like
poles of the master magnets may be passed successively past the
freely held magnets to induce reciprocable rotation of the latter.
Bolts 27 secure a drive ring 28 concentrically to and beneath the
turntable 25, the ring having an outer, circumferential groove 30
to receive a drive belt.
A mounting plate 31 of general triangular outline in plan, has a
central opening 32 to avoid interference with shaft 15 and its
flanged collar 16 and terminates in wings 33 which embrace a raised
end of the housing 10 (FIG. 1) to center the plate 31 in position.
If desired, the plate may be secured in place atop the housing, as
shown in FIGS. 1 and 2, or even formed as an integral part of the
housing. A fixed post 34 supports a motor 35 of standard
construction. By means of a pulley 36 and drive belt 37, motor 35
drives pulleys 38 and 39 having a common shaft 40, pulley 38 being
below and pulley 39 being above the mounting plate 31. Three
additional pulleys 42 having grooved sheaves are mounted for
rotation above the plate 31 in a position essentially tangent to an
arcuate path described by the periphery of the drive ring 28 upon
rotation of the turntable 25. A belt 43 of circular cross section
is trained around drive pulley 39 and between the pulleys 42 and
drive ring 28. It will be noted that the belt 43 is the only
physical connection between the annular turntable 25 and the rest
of the apparatus, such that the belt 43 both supports and rotates
the turntable 25 and its drive ring 28.
The combined sampling and magnet-recovering station C serves to
withdraw a portion of a sample from one cup while searching a
previous, already sampled cup to retrieve its subservient magnet
24. Referring especially to FIGS. 16 through 22, the sampling
device illustrated includes a plastic tube 44 slipped through a
bent metal sleeve 45 and secured by a setscrew 46 within a
transverse passage of a crook-mounting block 47. The tube
illustrated is of the aspirating type, although the present
invention does not reside in any particular takeoff means, and any
of those known in the art may be used. In a like manner, the sample
transmitted through tube 44 may be submitted to any testing
procedure desired. U.S. Pat. Nos. 2,797,149 to Skeggs; 2,879,141 to
Skeggs; and 3,081,158 to Winter describe various apparatus which
may be used in treating and/or testing successively drawn
samples.
A post 48 supports the crook-mounting block 47 and extends through
a slotted opening 50 in the top of the housing 10. By conventional
means, the post 48 is adapted to lift the tube 44 in a vertical
plane, as illustrated by the solid and broken lines in FIG. 17, and
to move the tube bodily to and from a sampling-withdrawal position
with respect to a cup 22 on the rotary plate 11, as illustrated by
the positions of FIGS. 16 and 18. Instead of moving substantially
only in a vertical plane, the sampling device may have a horizontal
component of motion as well. As indicated, the sampling device or
what is generally referred to in the art as the "takeoff" means
does not itself form part of the present invention and is not
therefore described here in detail. The takeoff means may comprise
any of those structures known in the art for this purpose. For
example, other illustrated structures may be found in the following
U.S. Pat. Nos. 3,038,349 to Isreeli; 3,127,773 to Blumenfeld;
3,134,263 to DeJong; 3,251,229 to Isreeli et al., 3,252,329 to
Heimann; and 3,282,651 to Ferrari et al.
In addition to necessarily removing the tube 44 to transpose it
from cup to cup on the rotary plate 11, the described motion of the
tube may also be for the purpose of dunking it in a washing
receptacle 51 secured on the housing 10 by a setscrew 52. A wash
liquid continually flows through the receptacle by means of inlet
and outlet conduits 53 and 54, respectively, to cleanse the tip of
the tube 44 and minimize crosscontamination of the samples.
After the contents of a cup 22 have been sampled, the minute
dipolar magnet 24 is recaptured for further use. The structure for
this purpose may be operated independently of the sampling device,
but it generally is more convenient to operate the sampling and
magnet-recovering means in unison and with the same or
complementary motions.
For example, as shown in FIGS. 16 through 22, in one form, a cross
arm 56 is secured by set screws 55 to both the sleeve 45 of the
sampling tube and a rigid support wire 57. The wire supports a
longitudinally slotted hollow column 58 having a partially closed
bottom end. A permanent magnet 60 is freely carried within the
column 58 and has a pin 61 extending through a longitudinal slot
62. The opening at the bottom of column 58 is not sufficiently
large to lose the magnet 60 which is adapted by means of the pin 61
to move from an operative position at the bottom end of column to a
retracted, inoperative position within the column. A striker arm 63
fixed to a side of the wash receptacle 51 engages the pin 61 of
column 58 when the latter is positioned over a recovery box 64.
OPERATION
In operation, a power switch 65 (FIG. 1) energizes electrical
components of the apparatus, including motor 35 and standard
indexing means for the rotary plate 11, and other like electrically
operated parts. The rotary plate moves only periodically and for a
short angular distance, that is, approximately a circumferential
distance from one cup 22 to another. On the other hand, motor 35
through the drive belt 43 continually rotates the turntable 25
through the drive ring 28. The net effect is that there is a
relative side-by-side motion (note FIG. 2) between the master or
controlling magnets 26 on the turntable and the minute, subservient
magnets 24 in the cups. FIGS. 3 through 9 sequentially illustrate
the preferred reaction obtained by passing a north and south pole
successively by a subservient magnet 24, so that the latter comes
alternately under the influence of poles of different polarity.
This produces a continuous rotation of a magnet 24 in the same
direction.
More particularly, as a trailing north pole, for example, of one
master magnet 26a passes a subservient magnet 24, its south pole is
attracted toward such north pole as illustrated by FIGS. 3 through
5. As the leading south pole of another master magnet 26b next
passes the same subservient magnet, its north pole is similarly
attracted toward that south pole of a master magnet as illustrated
by FIGS. 6 and 7, thereby completing substantially a
half-revolution of the rod-shaped subservient magnet. This action
is continued as other master magnets pass in succession, such as
magnet 26c as represented by FIGS. 8 and 9.
FIGS. 10 through 15 substantially illustrate another arrangement in
which like poles of a series of dipolar master magnets are
successively passed by a subservient magnet 24, so that the latter
is always under the influence of poles of the same polarity. This
produces a reciprocable rotation in a magnet 24.
For example, the dipolar master magnets may be placed transversely
to the direction of movement with like poles arranged on the same
side in the manner illustrated by FIGS. 10 through 15. The reverse
position in which all north poles are on the right, as viewed in
FIGS. 10 through 15, may also be used. As the south pole of one
magnet 26d passes a subservient magnet 24, its north pole becomes
magnetically "locked" to the master magnet and follows the movement
of its south pole, thereby completing substantially a one-half
revolution as illustrated by FIGS. 10 through 12. By the time
controlling magnet 26d begins to lose its magnetic attraction for
subservient magnet 26 because of increasing distance between them,
another master magnet 26e becomes sufficiently close to magnet 24
to influence it. The magnet 24 then reverses its rotation in a
direction back toward the entering magnet as shown by FIG. 13. This
action is then repeated as still another magnet 26f becomes
controlling so as ultimately to produce a back-and-forth,
reciprocable rotation in the subservient magnet 24.
The speed of rotation of the subservient magnets is dependent in
part upon the rate of relative motion between the two sets of
magnets and upon the spacing of the master magnet poles and the
cups 22. The spacing preferably is such that the subservient
magnets contained within the sample cups turn continuously and at a
relatively uniform rate of speed. Since each cup 22, for example,
has a generally hemispherical lower end, a subservient magnet tends
to ride with its ends in sliding engagement along a circular path
with the hemispherical wall. Each subservient magnet is constrained
in this manner generally to rotate about its longitudinal midpoint
centrally of the lower end of the cup containing it. The continued
rotation of the subservient magnets, whether unidirectional or
reciprocable, imparts an effective stirring action to the material
in the cups.
Meanwhile, as each cup is presented at the sampling station, post
48 moves the sampling tube 44 forwardly and into a cup 22 from
which a sample is conventionally aspirated. At the same time,
column 58 moves forwardly because of its connection through
crossarm 56 with the tube 44 and is immersed in an adjacent cup,
specifically a preceding cup that has already been sampled, as
illustrated best in FIGS. 16 and 21. The loosely held retrieving
magnet 60 normally rests on the bottom of column 58 due to its
weight and is free to attract and retain magnetically the
subservient magnet 24 within a cup 22 through the open bottom end
of the column.
When the tube 44 is retracted over the wash receptacle 51, column
58 naturally follows, as shown in FIG. 22. Similarly, when the tube
is next pivoted downwardly and into the receptacle 51 to be
cleansed, striker plate 63 engages pin 61 (FIG. 19), since the
column 58 follows the same motion. Upon further downward movement
of column 58, plate 63 forces pin 61 and the attached retrieving
magnet 60 to a retracted, inoperative position within the column
and thereby breaks the magnetic hold of magnet 60 on the recaptured
subservient magnet 24 which drops into the recovery box 64 (FIG.
20). Thereafter, plate 11 moves one more cup position, and the
sampling and recovery procedures as just described are
repeated.
In place of the master magnets, other electrical components which
produce and/or provide a succession of alternately north and south
magnetic poles passing by the subservient magnets in sample cups
may be employed to effect the stirring action. For example, a
stator coil, such as one used in a conventional electrical
induction motor, can be positioned along the path of the
subservient magnets. The movement of positive and negative magnetic
forces circumferentially of the coil causes the subservient magnets
to stir material in the cups as previously described.
Those skilled in the art will appreciate that various other changes
and modifications can be made in the preferred form described
herein without departing from the spirit and scope of the
invention.
* * * * *