U.S. patent number 3,776,184 [Application Number 05/231,255] was granted by the patent office on 1973-12-04 for apparatus for applying liquid samples to a surface.
This patent grant is currently assigned to The University of Surrey. Invention is credited to Arthur Denwood Richard Harrison.
United States Patent |
3,776,184 |
Harrison |
December 4, 1973 |
APPARATUS FOR APPLYING LIQUID SAMPLES TO A SURFACE
Abstract
An apparatus for automatically applying deposits of a liquid
sample to a surface for chromatographic analysis. The apparatus
employs a dispensing device which employs a plurality of separate
dispensing elements such as shaped components with looped portions,
small brushes or micro-pipettes, which are arranged in an elongate
row. The dispensing device is bodily moved in an arc between the
surface and vessels containing the liquid samples. Each of the
elements is dipped into one of the vessels to pick up a charge of
liquid and then moved into contact with the surface to transfer the
liquid to the surface as a defined deposit. Means, such as gearing,
is provided to ensure that the dispensing elements are moved
perpendicularly in relation to the surface when the latter are
about to transfer the liquid to the surface.
Inventors: |
Harrison; Arthur Denwood
Richard (Leatherhead, EN) |
Assignee: |
The University of Surrey
(Guilford, Surrey, EN)
|
Family
ID: |
22868423 |
Appl.
No.: |
05/231,255 |
Filed: |
March 2, 1972 |
Current U.S.
Class: |
118/243; 422/505;
73/864.24; 73/864.72; 422/50 |
Current CPC
Class: |
G01N
30/91 (20130101) |
Current International
Class: |
G01N
30/91 (20060101); G01N 30/00 (20060101); B67d
005/62 () |
Field of
Search: |
;118/243 ;23/253R,292
;73/423A,424 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Rimrodt; Louis K.
Claims
What I claim is:
1. An apparatus for automatically applying discrete deposits of
liquid to a surface of a sheet member; said apparatus
comprising:
a housing which defines a fixed loading station and a fixed
delivery station, the sheet member being received at the delivery
station and the loading station serving to receive a supply of
liquid for application to said member; a dispensing device; driving
means for moving said dispensing device in a non-linear cyclic
manner between delivery and loading positions located at said
delivery and loading stations, respectively; the dispensing device
including a plurality of depending dispensing elements, each
dispensing element being capable of taking up a pre-determined
quantity of liquid from the liquid supply when the dispensing
device is at the loading position and each dispensing element being
capable of dispensing said quantity of liquid to the sheet member
when the dispensing device is at the delivery position.
2. An apparatus according to claim 1, wherein the dispensing device
is in the form of a bar carrying said dispensing elements, said bar
being detachably secured to a support member coupled to said
driving means.
3. An apparatus according to claim 2, wherein each dispensing
element is in the form of a shaped component having a looped
portion defining a reception area for the liquid.
4. An apparatus according to claim 3, wherein the shaped component
is a piece of resilient wire affixed to an elongate member slidably
received in a bore in the bar, the elongate member being provided
with a collar for engaging an upper face of the bar.
5. An apparatus according to claim 2, wherein each of the
dispensing elements is a micro-pipette and there is further
provided means for supplying gas to each micro-pipette to effect
dispensing of said pre-determined quantity of liquid.
6. An apparatus according to claim 2, wherein the support member is
pivotably supported by a pair of levers and the driving means
serves to move said support member in an arcuate path.
7. An apparatus according to claim 6, wherein there is further
provided a system of gearing for maintaining the dispensing
elements in a substantially upright position at least in relation
to the upper surface of the sheet member when the dispensing device
approaches the delivery position.
8. An apparatus according to claim 7, wherein said gearing system
comprises a first fixed gearwheel, a second gearwheel attached to
said support member and an intermediate gearwheel pivotably
attached to one of said levers and meshing with the first and
second gearwheels.
9. An apparatus according to claim 8, wherein the gearing system
further comprises a fixed quadrant gear and a further gearwheel
affixed to said support member.
10. An apparatus according to claim 1, wherein there is further
provided a system of gearing for maintaining the dispensing
elements in a substantially upright position at least in relation
to the upper surface of the sheet member when the dispensing device
approaches the delivery position.
11. An apparatus according to claim 1, wherein each dispensing
element is composed of a group of straight fibres.
12. An aparatus according to claim 1, wherein the driving means
includes endless members the dispensing device being pivotally
connected to the endless members and means for moving said endless
members.
13. An apparatus according to claim 12, wherein each endless member
is entrained around a pair of sprocket wheels disposed one above
another, one of the sprocket wheels being driven, the endless
member having sections arranged to bring the dispensing elements
vertically downwards to the loading and delivery stations .
14. An apparatus according to claim 1 wherein there is provided
means for producing flexibility of each dispensing element.
Description
BACKGROUND TO THE INVENTION
The present invention relates to an apparatus for applying liquid
samples to a surface.
In paper or thin-layer chromatography it is often necessary to
apply a small volume (typically in the order of a few microlitres)
of each of a group of liquid samples to a surface to provide a
deposit for subsequent analysis usually after drying. Such
application can be done by hand and this is particularly irksome
and tedious. The majority of known forms of apparatus for
performing this task automatically are costly and complicated and
have a limited use.
A general object of the present invention is to provide an improved
form of apparatus. A further object of the invention is to provide
a relatively inexpensive, simple, yet versatile, form of
apparatus.
SUMMARY OF THE INVENTION
The present invention provides an apparatus for automatically
applying discrete deposits of liquid to a surface of a sheet
member; said apparatus comprising:
A housing which defines a fixed loading station and a fixed
delivery station, the sheet member being received at the delivery
station and the loading station serving to receive a supply of
liquid for application to said sheet member; a dispensing device;
driving means for moving said dispensing device in a non-linear
cyclic manner between delivery and loading positions located at
said delivery and loading stations, respectively; the dispensing
device including a plurality of depending dispensing elements, each
dispensing element being capable of taking up a predetermined
quantity of liquid from the liquid supply when the dispensing
device is at the loading position and each dispensing element being
capable of dispensing said quantity of liquid to the sheet member
when the dispensing device is at the delivery position.
The term sheet member includes metal or glass plates, paper, thin
films of plastics or the like and culture or immunological plates
with or without wells.
Preferably the dispensing elements are inherently flexible or
flexibly mounted.
Each dispensing element may be in the form of a shaped component
having a looped portion defining a reception area for the liquid.
It is particularly convenient to form each component from a piece
of resilient wire bent so as to form a loop, which may be open or
closed, at its lower end. The looped portion of the component
defines a reception area for receiving the quantity of liquid
sample for transference to the sheet member.
Each of the dispensing elements may also be constructed as a group
of straight fibres.
The dispensing device may be in the form of a bar carrying said
dispensing elements, said bar being detachably secured to a support
member coupled to said driving means.
It is desirable to provide some form of gearing for compensating
any tendency of the dispensing elements to take a non-perpendicular
position in relation to the upper surface of the sheet member. In
this way the elements may be arranged to descend vertically and
contact the sheet member without skidding over the upper surface so
as to normally deposit a precisely defined spot of liquid.
The invention may be understood more readily and various other
features of the invention may become more apparent from
consideration of the following description:
BRIEF DESCRIPTION OF DRAWINGS
An embodiment of the invention will now be described by way of
example only, with reference to the accompanying drawings,
wherein:
FIG. 1 is a schematic side elevation of an apparatus made in
accordance with the invention;
FIG. 2 is a schematic plan view of the apparatus shown in FIG.
1;
FIG. 3 is a perspective enlarged view of part of the dispensing
device of the apparatus;
FIG. 4 is a schematic illustration of one of the dispensing
elements of the dispensing device;
FIG. 5 is a schematic illustration of an alternative construction
for the dispensing element;
FIG. 6 is a schematic illustration of another form of dispensing
element;
FIG. 7 depicts a further type of dispensing element;
FIG. 8 is a schematic side elevation of a modified part of the
apparatus; and
FIG. 9 is a schematic plan view of the part of the apparatus shown
in FIG. 7.
DESCRIPTION OF PREFERRED EMBODIMENTS
Referring initially to FIGS. 1 and 2 there is shown an apparatus
composed of a housing assembled from side and end walls 10, 11, a
base 12 and a flanged top wall 13. The side walls 10 have cut out
portions 59 and for the sake of clarity, one of the side walls 10
is removed in the view of FIG. 1.
The upper surface of the top wall 13 serves as a delivery station
and receives a sheet member 5 to be treated. A channel shaped
member 51 is supported at the top of the apparatus and at the left
hand side of FIGS. 1 and 2. This member 51 serves as a loading
station and receives one or more vessels 50 containing solutions to
be applied to the member 5 as a collection of defined discrete
spots. The member 5 would usually be a thin layer of material of
size 20 cm .times. 20 cm., commonly emplyed in chromatographic
analysis.
Within the housing or externally thereof there is provided a prime
mover in the form of an electric motor 14 which is drivably coupled
via gearing 81 and an endless belt or chain 15 to a rotatable drive
wheel 16. The wheel 16 is carried by a shaft 17 which may extend
between the side walls 10. An arm 19 is pivotably supported on a
bracket 20 and mounted in a generally upright position. A
connecting rod 18 is pivotably linked to the arm 19 at about the
centre thereof. The rod 18 is pivotably supported on a short shaft
21 mounted on the wheel 16 at a position radially offset from the
centre thereof. Thus, rotation of the wheel 16 will cause the rod
18 to move in an eccentric manner to thereby oscillate the arm 19
in the direction of arrows K in FIG. 1. The free end of the arm 19
is coupled to a further connecting rod 22 at a pivotal joint 23 and
this rod 22 is journalled onto a shaft 24 having a lever 2 attached
to each end. The ends of the shaft 24 extend through the cut outs
59 so that the levers 2 are disposed outwardly of the side walls
10. The pair of levers 2 are each pivotably attached to a shaft 25
journalled to the upper part of the side walls 10 of the housing.
Each lever 2 has a bifurcated portion 3 which seats on a flattened
zone on the shaft 24. The shaft 24 has threaded end portions
receiving nuts 4 used to clamp the levers 2 thereto. By loosening
these nuts the shaft 24 can be positionally re-adjusted.
An extension of the shaft 25 carries a fixed gearwheel 26 which is
non-rotatable. An elongate support member 27 is pivotably mounted
between the ends of the levers 2 and is affixed to the centre of a
further gearwheel 28. An intermediate small gearwheel 29 meshes
with the gearwheels 26, 28 and is pivotably connected to the
associated lever 2.
A dispensing device, shown more particularly in FIGS. 3 and 4 is
attached to the support member 27. The dispensing device is in the
form of an elongate bar 30 which is preferably made from a
synthetic plastics material, which supports a series of separate
dispensing elements. More particularly the bar 30 has a series of
equispaced bores 31 therein. Each bore 31 slidably receives a tube
32 having a collar 33 near its upper end. The tube 32 is preferably
provided with fins or the like (not shown) to prevent the tube 32
from rotating within the associated bore 31. This collar 33 may be
a force fit but slidable along the tube 32 to permit adjustment of
the length of the tube 32 projecting below the bar 30. Each tube 32
may be made from 23 s.w.g. stainless steel tubing. A shaped
dispensing element 34 is held captive by each of the tubes 32 and
depends therefrom. In this construction each element 34 is made
from resilient wire such as 35 s.w.g. stainless steel spring wire
(18/8) bent into shape. As shown in FIG. 4, each element 34 has a
first depending portion 90 which extends into the associated tube
32 and which may be secured therein with the aid of an adhesive,
preferably an epoxy resin adhesive such as "Araldite" (Registered
Trade Mark). The portion 90 of each element 34 adjoins a further
depending portion 91 offset from the axis of the associated tube
32. The portion 91 in turn adjoins a closed or substantially closed
loop 92 which may be of circular configuration as illustrated. The
loop 92 defines a reception area 94 for a film of solution and lies
in a plane parallel to a radial plane of the associated tube 32.
The loop 92 is coaxial with the tube 32. The wire from which the
elements 34 are formed can be air-annealed and the oxide film thus
formed on the loops 92 of the elements is advantageous in wetting
the loops 92.
Instead of employing tubes 32 with the elements 34 it is possible,
as shown in FIG. 5, to utilize rods 38. In this case the portion 90
of each of the elements 34 can be bent around the associated rod 38
and secured thereto for example by spot welding. Instead of forming
the elements 34 from bent wire these components can be produced
from a plastics material such as nylon.
In another form, depicted in FIG. 7, the elements 34 are
constructed from a group of straight fibres 150 resembling a small
brush again connected to the tubes 32 or rods 38.
The entire dispensing device 30, 32, 34 can be removed and replaced
with other dispensing devices having elements 34 with different
spacings or with other arrangements.
In FIG. 6 there is shown a device with different forms of
dispensing elements. In this case the dispensing elements are in
the form of micro-pipettes 60 located in the bores 31 in the bar
30. The micro-pipettes 60 each have a spring 63 disposed between a
collar 64 and the upper face of the bar 30. Each micro-pipette 60
accepts a charge of liquid automatically and when the charge is to
be expelled onto the sheet member 5 air pressure can be fed to the
micro-pipette 60 via a flexible conduit 61 connected thereto.
Besides applying deposits to a planar sheet member 5 the dispensing
elements can also apply sera, for example, to the wells of
immunological test plates.
The operation of the apparatus is as follows:
The energization of the motor 14 causes the coupled system of
levers to move the support members 27 back and forth along an
arcuate path generally denoted P in FIG. 1 and the support member
27 moves between a loading position denoted P1 and as a delivery
position denoted P2. The gearing 26, 28, 29 acts to ensure that the
dispensing elements 34 maintain a substantially vertical position
and restrains any swinging motion of the member 27. One or more
vessels 50 contain the solution or other liquid which is to be
applied to the member 5 and are disposed in the loading position
51. As the levers 2 swing in an anti-clockwise movement towards the
vessel or vessel 50 the elements 34 will be immersed into the or
each solution and the loops 92 each become charged with a quantity
of solution. When the levers 2 swing back in the reverse direction
a film or droplet of solution will be retained by each of the loops
92. When the support member 27 reaches the delivery position P2 the
loops 92 will just gently contact the member 5 in a clean
non-skidding movement to apply a deposit of the solution of known
volume to the upper surface of the member 5. The collars 33 of the
tubes 32 can be relatively adjusted so that the loops 92 all
contact the member 5 at the same time without disturbing the
latter. The sheet member 5 can be moved in the direction of arrow A
or B shown in FIG. 2 between successive applications so that
streaks of regularly deposited solution can be applied to the
member 5. The cycle of movement of the dispensing device can be
repeated.
To further improve the depositing action of the elements 34 the
apparatus can be modified as shown in FIGS. 8 and 9 to include
further gearing. As shown in these Figures the gearwheel 28 is a
tight force fit relative to the support member 27 so that normally
the member 27 moves with the gearwheel 28. A quadrant gear 100 is
fixed to the housing of the apparatus and a small gearwheel 101 is
provided which is capable of meshing with the gear 100 only when
the support member 27 is near the delivery position P2. This
gearwheel 101 is affixed to the support member 27. As the levers 2
swing clockwise towards the delivery position P2 the gearwheel 28
partially rotates to bring the elements 34 into a vertical
disposition. At the final stage of this movement the elements 34
would normally perform a small horizontal movement but the
gearwheel 101 now meshes with the gear 100 and takes over from the
gearwheel 28 in controlling the position of the member 27 and the
elements 34.
In another construction the means for moving the dispensing device
can be a pair of sprocket wheels disposed at, or near, the sides of
the apparatus. Each pair of sprocket wheels would be of equal
diameter disposed one above another with a chain or the equivalent
entrained thereabout. The support member 27 would be pivotably
connected to the chains. The lowermost sprocket wheels would be
mounted on a common shaft which is rotated back and forth by
suitable drive means. The chains would have sections of their
length extending substantially vertically and generally arranged to
ensure verticality of the elements 34 at the delivery and loading
positions. In a more elaborate arrangement the chains may be guided
around further sprocket wheels and the drive means rotates some of
the sprocket wheels continuously to bring the elements 34 to other
operating stations effecting rinsing or sterilizing, for
example.
Provision can be made for halting the operation of the apparatus
after solution has been deposited on a member 5 to enable the
solution to be dried. The drying periods such as are commonly
needed in chromatographic work may be shortened by, for example,
providing a gas stream which is directed at the deposited solution
when applied.
The reproducibility of single deliveries by the apparatus has been
found to produce better than 6 percent coefficient of variation
(C.V) for aqueous or non-polar solutions compared with a C.V. of
around 2 percent for conventional techniques with syringe-type
applicators. In serial applications the overall C.V. may be lower
than 6 percent but this degree of reproducibility is adequate for
the majority of purposes.
The loops 92 are easy to clean without dismantling, unlike
syringe-type applicators and any residual rinsing liquid can be
removed by operating the apparatus with a sheet of absorbent
material used as the member 5.
* * * * *