Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
1066674 :
. The subject matter of the present invention is a mouth filter device
for use with pipettes which in use require mouth-applied suction to draw a -;
liquid into the pipette.
Chemists, biologists, and others skilled in the art readily appre-
ciate the hazard involved in the careless use of a pipette. That is, if while -~
using a pipette the technician!s attention is distracted from the task at ~ -
hand--that of drawing liquid into the pipette by the application of mouth-
applied suction--it is easily possible for the technician to end up with a
mouthful of the liquid being drawn. Many have been the chemistry students
and chemists who have had to spit out some acid or other harmful chemical as
the result of the use of a pipette without close attention. In the areas of
biology, microbiology, and the medical profession, there is the still further
hazard, in the use of a pipette, of the ingestion of harmful bacteria present
in the liquid being drawn into the pipette. Protection for the technician is
here required, not just against the careless use of the pipette but even when
the technician uses the pipette with utmost care. That is, the biologist or
metical technician might, on occasion, be sucking into the pipette a liquid
pregnant with harmful bacteria which, absent protection, could reach the mouth,
by way of the vapor above the liquid, albeit the pipette would be carefully -.
uset such that the liquid itself did not reach the mouth.
The present invention provides a practical, low-cost device for
; protecting the chemist, biologist, medical technician or other person using
a pipette or the like from the aforesaid hazards.
According to the present invention there is provided a mouth filter
device for use with pipettes where suction is applied by the mouth to draw
liquid into the pipette, said device comprising a flat, cylindrical, organic
resin housing, a round filter membrane in and extending transverse to the axis
of said housing and in sealed relationship with said housing so as to divide
sait housing into an inlet chamber on one side of said filter membrane and an
exit chamber on the other side of said filter membrane, said filter membrane -
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being hydrophobic thereby to allow the passage of gas therethrough while pre-
venting the passage of liquid therethrough and said filter membrane having a
submicron pore size sufficiently small to prevent the passage of bacteria
therethrough, a tubular extension on and integral with one axial end of said .
housing extending axially from and communicating with said inlet chamber, a
tubular extension on and integral with the other axial end of said housing
extending axially from and communicating with said exit chamber, an elastomer-
ic tube having one end thereof connected and communicating with said first
mentioned extension, the other end of said tube being adapted to be fitted in
10 sealed relationship to the pipette, and an organic resin mouthpiece connected
to said second mentioned tubular extension and having an opening therethrough
communicating with said exit chamber whereby mouth-applied suction to said
mouthpiece creates suction through the filter membrane and said tube to draw -
liquid into the pipette to which the tube is fitted thereby to draw liquid
thereinto, said ~ilter membrane assuring against any of the liquid or any
bacteria therein reaching the mouth.
The invention will now be described in detail, in part
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by reference to the accompanying drawings in which:
FIGURE 1 is a perspective view of a mouth filter
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device made in accordance with the invention;
FIGURE 2 is a side view in cross-section, and in some-
what enlarged scale, of a portion of the device shown in FIGUREl; and
FIGURE 3 is a perspective view of another embodiment
of the ~nvention.
Referring now to FIGURES 1 and 2, the mouth filter de-
vice of the present invention comprises a flat, cylindrical,rigid, transparent organic resin housing 2, there being a round
filter membrane 4 extending transverse to the axis of the housing
and in sealed relationship with the cylindrical side wall of the
; housing. Hence, the filter membrane divides the housing into an
inlet chamber 6 on one side of the filter membrane and an exit
chamber 8 on the other side of the filter membrane. For ample
support of the filter membrane, which may be of relatively
delicate construction, the housing can be provided with circum-
ferentially spaced, radially extending upper and lower ribs, 10
and 12 respectively, which contact the membrane and provide the
desired physical support. The housing can be constructed of
; upper and lower transparent organic resin moldings which are
snapped together with the membrane therebetween, as shown, after
, which the molding can be heat sealed together around the circum-
s` 25 ference thereof so as to provide a hermetic seal.
; The filter membrane 4 must be hydrophobic, i.e. it
must be such that it enables the passage therethrough of gas but
à prevents the passage therethrough of liquid. Still further, the
; filter membrane must constitute a bacteria barrier, which means
30 that the filter membrane must have a submicron pore siz~- suffi-
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ciently small to block the migration of bacteria from one side
to the other thereof. Such hydrophobic bacteria-barrier mem-
branes are already known in the art and are commercially avail-
able, as exemplified by the filter membrane marketed by the
assignee of the present invention under the trademark UAcropor'',
- such membrane having a pore size of from about .2 to .5 microns.
Such a filter membrane consists of a unitary organic resin film,
typically .005 inches in thickness, having random and irregular
passages therethrough of sufficiently small dimensions to block
the passage of anything, including bacteria, having a size
greater than the aforesaid .5 microns.
Extending axially from and integral with one axial end
of the housing and communicating with the inlet chamber 6 is a
tubular extension 14. Extending axially from and integral with
the opposite axial end wall of the housing is a tubular exten-
sion 16 which communicates with the exit chamber 8.
Connected to and communicating with the tubular exten-
sion 14 is a flexible elastomeric tube 18. The end 20 of the
elastomeric tube 18 is, in its unstretched condition, of some-
, 20 what lesser internal diameter than the external diameter of the
lower end of the housing extension 14 and is sealingly secured
thereto simply by way of its inherent resiliency which provides
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an excellent mechanical and leak-free connection. The opposite
end 22 of the flexible tube is adapted to be fitted in sealed
relationship to the upper end 24 of a pipette into which it is
desired to draw the liquid. The connection between the end 22
of the flexible tube and the upper end 24 of the pipette is
similar to the connection between the end 20 of the flexible
tube and the tubular projection 14 of the filter membrane hous-
ing. That is, the normal unstretched internal diameter of the
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flexible tube is somewhat less than the external diameter of the
upper end of the pipette, and the attachment of the end of the
flexible tube to the pipette is accomplished by a stretching of
the end of the elastomeric tube thereby providing a good mechan-
ical and leak proof, though rapidly detachable, connection.
Connected to the tubular extension 16 is a molded
organic resin mouthpiece 26. The mouthpiece has an opening 28
therethrough which communicates with the passage through the
extension 16 and hence communicates with the exit chamber of the
filter membrane housing. In the embodiment shown in FIGURES 1
and 2, there is a friction fit between the tapered outer surface
of the lower end 30 of the mouthpiece and the tapered interior
surface of the extension 16, the friction fit being ample to
maintain the mouthpiece secured to the extension in sealed
relationship therewith.
It is preferred that the flexible tube be at least
about 12 inches long so that when the flexible tube is connected
to the pipette, the technician who, with his mouth draws the
' vacuum through the mouthpiece, can be this distance away, later-
20 ally, from the pipette so as to be able to clearly view the
liquid level attained in the pipette as the mouth suction is
` applied. On the other hand, a tube length of greater than 24
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inches is cumbersome and serves no useful purpose.
In operation, the chemist, biologist, or other tech-
nician connects the end of the flexible tube to the pipette and
then, with the pipette inserted into the liquid desired to be
drawn, applies mouth suction to the mouthpiece 26 until the
desired level of the liquid in the pipette is attained. But in
the event the technician's attention should be distracted, the
filter membrane 4 absolutely insures against the liquid being
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drawn into the technicianls mouth since the filter membrane 4 is
hydrophobic and hence blocks the passage of any liquid--though
allowing the passage of gas therethrough. As regards use by
bIologists where the liquid being drawn into the pipette might
contain virulent bacteria, the filter membrane of the device,
being a bacteria barrier, fully protects the technician against
the ingestion of the bacteria even though such bacteria might be
present in the vapor phase above the liquid. Hence, the device
of the present invention provides a low-cost, convenient way to
protect technical personnel who are required, by mouth-applied
suction, to withdraw liquid chemical or biological samples into
pipettes.
The FIGURE 3 embodiment differs from that of FIGURES
1 and 2 chiefly in that when in use, the filter membrane is
located more closely adjacent the pipette. Referring to FIGURE
; 3, the filter housing 30, the filter membrane (not shown) there-
in and the inlet and outlet tubular extensions, 32 and 34 respec-
tively, of the housing are all identical in structure to the
like components shown in the FIGURE 1-2 embodiment; however, in
the FIGURE 3 embodiment the mouthpiece 36 is connected to the
outlet tubular extension 34 of the filter housing by a flexible
elastomeric tube 38 which can be the same as, but preferably
shorter than, the flexible elastomeric tube 18 of the FIGURE 1-2
embodiment. Connected to the inlet tubular extension 32 of the
filter housing is an elastomeric tube 40 which is of generally
conical external shape. The tube can be relatively short--
about 3/4" to 1", for example. When the FIGURE 3 embodiment is
used, the conical elastomeric tube 40 is inserted into the upper
end of the pipette until a good seal is accompl~shed between the
pipette and the elastomeric tube which is relatively soft and
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hence enables a good s-eal, Because of the conical shape of the
elastomeric tube 40, th.e filter can be used with any of a vari-
ety of different sized pipettes having different diameters, the
elastomeric tube extending only a short distance into a pipette
of small diameter and extending further into a pipette of larger
diameter. In FIGURE 3, 42 is the upper end of a pipette into
which the conical tube 40 has been inserted.
It will be understood that whereas the invention has
been described in its particulars with reference to preferred
. 10 embodiments thereof, various changes and modifications may be
:. made all within the full and intended scope of the claims which
follow. .
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