Chemical apparatus and process disinfecting – deodorizing – preser – Control element responsive to a sensed operating condition
Reexamination Certificate
2002-02-05
2004-03-09
Ludlow, Jan (Department: 1743)
Chemical apparatus and process disinfecting, deodorizing, preser
Control element responsive to a sensed operating condition
C073S864010, C073S864130, C083S167000, C083S919000, C204S613000, C422S091000, C422S105000
Reexamination Certificate
active
06702990
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to pipettes and pipette tips.
2. Prior Art
An air pipette is a laboratory tool for transferring small but precise quantities of fluids between containers. A typical pipette shown in
FIG. 1
is comprised of a hand-held housing
10
with a suction tube
11
attached to a lower end. An actuation button
12
and a tip eject button
13
are positioned at the top of housing
10
. Actuation button
12
is connected to a piston
14
inside tube
11
, and is biased by a spring to the uppermost or retracted position shown. Tip eject button
13
is connected to an ejection arm
15
positioned around the lower end of suction tube
11
. A disposable tubular pipette tip
16
is attached to suction tube
11
by fitting an open proximal end of pipette tip
16
around the lower end of suction tube
11
. A porous hydrophobic filter
17
is positioned within pipette tip
16
. Typical filters are disclosed in U.S. Pat. No. 6,117,394 to Smith, U.S. Pat. No. 6,045,757 to Moriarty et al., and U.S. Pat. No. 5,496,523 to Gazit et al. Such filters are made of incompressible materials and immovably fixed inside their pipette tips.
To transfer a fluid from one container to another, actuation button
12
is depressed to a first stop to move piston
14
downward inside suction tube
11
. Pipette tip
16
is dipped into the fluid, and actuation button
12
is released and allowed to retract. When piston
14
is moved upward, a low pressure within pipette tip
16
is generated to draw in the fluid. Filter
17
has pores which allow air to pass through for sucking in the fluid, but which are fine enough to prevent the fluid from passing through at the working pressure of the pipette. Therefore, filter
17
prevents the fluid from contaminating suction tube
11
.
After the fluid is drawn in, pipette tip
16
is positioned over another container, and actuation button
12
is depressed to move piston
14
past the first stop to a second stop and discharge the fluid. Tip eject button
13
is depressed to push the used pipette tip
16
off suction tube
11
with ejection arm
15
. A clean pipette tip is attached to suction tube
11
for transferring another fluid to avoid contaminating the second fluid with the first fluid.
Sometimes semi-solids, such as gels, are also transferred in laboratory work. Although a conventional pipette can cut a gel spot by pressing the tip into a gel sheet, the gel spot tends to get sucked up fairly high in the tip. When the piston is depressed, the gel spot is moved downward unevenly and break the air seal between the gel spot and the tip before the gel spot is ejected.
BRIEF SUMMARY OF THE INVENTION
The objects of the present spot picker are:
to provide a pipette with a disposable cutting tip for cutting a spot from a semi-solid material;
to protect the pipette from being contaminated by the material; and
to reliably eject the spot from the cutting tip.
The present spot picker is comprised of a pipette and a disposable cutting tip. The pipette is comprised of a housing with a suction tube projecting from a lower end. An actuation button is positioned at the top end of the housing. The actuation button is connected to a piston inside the suction tube. A plunger attached to the piston has a lower end positioned outside the suction tube. The cutting tip is comprised of a hollow tube with an open proximal end attached to the suction tube. A compressible porous hydrophobic filter is securely but movably positioned within the hollow tube. The cutting tip cuts a gel spot when its open lower end is pushed into a sheet of gel. The plunger pushes the filter outward to discharge the gel spot from the cutting tip when the actuation button is fully depressed.
REFERENCES:
patent: 3815790 (1974-06-01), Allen et al.
patent: 4418580 (1983-12-01), Satchell et al.
patent: 5210927 (1993-05-01), Lamont et al.
patent: 5217591 (1993-06-01), Gombocz et al.
patent: 5496523 (1996-03-01), Gazit et al.
patent: 6117394 (2000-09-01), Smith
patent: 6342143 (2002-01-01), Minden
patent: 6565728 (2003-05-01), Kozulic
Camacho Joseph
Flanagan Richard
Lo Jack
Ludlow Jan
The Gel Company
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