An automatic apparatus is described for microbiologically sampling surface using a cotton swab which eliminates human error. The apparatus includes a self-powered transport device, such as a motor-driven wheeled cart, which mounts a swabbing motor drive for a crank arm which supports a swab in the free end thereof. The swabbing motor is pivotably mounted and an actuator rod movable responsive to the cart traveling a predetermined distance provides lifting of the swab from the surface being sampled and reversal of the direction of travel of the cart

Mills, S. M.

Wilkins, J. R.

English

NASA Technical Reports Server

REPLY TO
ATTN OF: GP
\&^A
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
WASHINGTON, D.C. 20546
NOV 7 1974
TO: KSI/Scientific & Technical Information Division
Attn: Miss Winnie M. Morgan
FROM: GP/Office of Assistant General
Counsel for Patent Matters
SUBJECT: Announcement of NASA-Owned U.S. Patents in STAR
In accordance with the procedures agreed upon by Code GP
and Code KSI, the attached NASA-owned U.S. Patent is being
forwarded for abstracting and announcement in NASA STAR.
The following information is provided;
U.S. Patent No. ; 3^^
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Source (if applicable)
NASA Patent case No.
rw u^ vxT
NOTE - If this patent covers an invention made by a corporate
employee of a NASA Contractor, the following is applicable;
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Pursuant to Section 305(a) of the National Aeronautics and
Space- Act, the name of the Administrator of NASA appears on
the first page of the patent; however, the name of the actual
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the Specification, following the words "...with respect to
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<
Bonnie L. Woerner .
Enclosure
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https://ntrs.nasa.gov/search.jsp?R=19750004200 2020-03-19T20:32:40+00:00Z
FT*. 3,841,973
Oct 15,1974 J.R.W.LK.NSETAL
APPARATUS FOR MICROBIOLOGICAL SAMPLING
2 Sheets-Sheet 1
Filed Jan. 24, 1973
Oct. 15, 1974 j. R.WILKINS ETAL 3,841,973
APPARATUS FOR MICROBIOLOGICAL SAMPLING
Filed Jan. 24. 1973 2 Sheets-Sheet 2
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(NASA-Case-LAB-11069-1) APPARATUS FOE
MICROBIOLOGICAL SAMPLING Patent (NASA)
5 p CSCL 06M
00/35
United States Patent Office
N75-12272"
Unclas
52988 ,
~~ 3,841,973
Patented Oct. 15, 1974
3,841,973
APPARATUS FOR MICROBIOLOGICAL SAMPLING
Judd R. Wilkins and Stacey M. Mills, Hampton, Va.,
assignors to the United States of America as repre-
sented by the Administrator of the National Aeronautics 5
and Space Administration
Filed Jan. 24,1973, Ser. No. 326,198
Int. Cl. C12k 1/10
V.S. Cl. 195—127 10 Claims
10
ABSTRACT OF THE DISCLOSURE
An automatic apparatus for microbiologically sampling
surfaces using a cotton swab is provided which eliminates
human error normally associated with this process. The
apparatus includes a self-powered transport device, such
as a motor-driven wheeled cart, which mounts a swabbing
motor drive for a crank arm which supports a swab in
the free end thereof. The swabbing motor is pivotably
mounted and an actuator rod movable responsive to the
cart traveling a predetermined distance provides lifting of
the swab from the surface being sampled and reversal of
the direction of travel of the cart.
2o
ORIGIN OF THE INVENTION 25
The invention described herein was made by employees
of the United States Government and may be manufac-
tured and used by or for the Government for govern-
mental purposes without the payment of any royalties 39
thereon or therefor.
FIELD OF THE INVENTION
The present invention relates to a method and appara-
tus for microbiologically sampling surfaces using cotton 35
swabs.
BACKGROUND OF THE INVENTION
A number of techniques are available for sampling or
enumerating micro-organisms on surfaces. These include
the .swab-rinse method, rinse tests, the agar contact tech-
nique, direct agar surface plating and vacuum probe
techniques. The advantages and disadvantages of these
techniques are discussed in the literature and reference
is made to Favero et al., "Microbiological Sampling of
Surfaces," of Appl. Bact., Vol. 31, 1968, pages 336-343;
Petersen et al., "Michrobiological Evaluation of the Vacu-
um Probe Sampler," Appl. Microbiol., Vol. 18, 1969,
pages 1002-1006; Vesley, "Survey of Microbiological
Techniques for Recovery from Surfaces," "Proceedings
of Spacecraft Sterilization Technology" meeting, NASA
SP-108, 1965, pages 147-153; and Walter, "Symposium
of Methods for Determining Bacterial Contamination on
Surfaces," Bact. Rev. Vol. 19, 1955, pages 284 to 287.
It is generally agreed that of all of these techniques,
those utilizing swabbing and, in particular, those in which
a surface is swabbed with a moist cotton swab and then
rolled over an agar medium yields the quantitative in-
formation, especially from surfaces with known concen-
trations of contaminants. A primary reason for the in-
effectiveness of this method stems from the manner in
which the surface in question is sampled. Before explor-
ing this point further, it should be noted that the gen-
eral practice in sampling of this kind involves hand
swabbing, in orthogonal directions, of the surface under
a sterile template or a marked-off area, the surface being
swabbed in a first direction and then being swabbed
at right angles to this direction. Reference is made
to Angelotti et al., "Comparative Evaluation of the
Cotton Swab Rodac Methods for the Recovery of Bacillus
Substilis Spore Contamination From Stainless-Steel Sur-
40
45
50
55
60
65
70
faces," Hlth. Lab. Sci., Vol. 1, 1964, pages 289-296, for
an example of detailed instructions given for this proce-
dure. In any event, as stated, it is generally accepted that
swabbing techniques are subject to a number of inherent
errors and actual experience has indicated a poor correla-
tion between the amount of contamination present and
that recovered by different investigators using swabbing
techniques. As mentioned above, a primary source of
error lies in the manner in which the swabbing is per-
formed or, more particularly, in the fact that no two
people use a swab in precisely the same way. For ex-
ample, the swabbing techniques of two different investiga-
tors might differ as to speed as well as the angle and
pressure applied to the swab. Because of the high preci-
sion necessary in the sampling procedure these differences
can mean differences in results.
Because of the attractive features of the cotton swab
method, and in particular, its ready availability, simplicity
and low cost, the method is used extensively despite the
limitations discussed above. Attempts to regularize the
procedure using detailed instructions are perhaps of some
help but the human factor, i.e., the fact that even the
same investigator, much less two different investigators,
will almost inevitably produce different results, has here-
tofore placed a severe handicap on this method particu-
larly where a high degree of accuracy is required.
SUMMARY OF THE INVENTION
In accordance with the present invention, an automatic
swabbing apparatus is provided which enables swabbing of
a surface without human involvement and which thereby
eliminates the human error factor normally associated
with this technique. The apparatus enables control of
swabbing speed, rotation of the swab, swab pressure and
the swabbing angle while providing substantially uniform,
complete coverage of the area to be sampled.
According to a preferred embodiment thereof, the ap-
paratus comprises a self-powdered transport device, such
as a motor-driven wheeled cart, on which an automatic
swabbing device is mounted. The swabbing device pref-
erably comprises a pivotably mounted swabbing motor
which imparts a swabbing motion to an elongate crank
arm in the free end of which a swab is mounted. With the
motor pivoted so that the swab contacts the surface to be
sampled, a combined side-to-side and spiraling motion is
imparted to the swab.
An actuator bar mounted for axial movement on the
cart cooperates with an obstacle placed in the path of the
cart to limit the swabbing operation to a predetermined
area. In accordance with a preferred embodiment, move-
ment of the actuator bar a predetermined distance causes
actuation of a limit microswitch which, in turn, causes a
reversal of the direction of movement of the cart. The
actuator bar is also arranged to contact a lift bar affixed
to the pivot shaft for the swabbing motor so that the swab
is lifted from the sampled surface at substantially the same
time as the cart reverses direction.
Other features and advantages of the invention will
be set forth in, or apparent from, the detailed description
of a preferred embodiment found hereinbelow.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagrammatic perspective view of an auto-
matic sampling apparatus in accordance with a presently
preferred embodiment of the invention;
FIG. 2 is a front view, to an enlarged scale, of a de-
tail of the apparatus of FIG. 1; and
FIG. 3 is a schematic circuit diagram of the electrical
control system for the apparatus of FIG. 1.
3,841,973
BRIEF DESCRIPTION OF THE DRAWINGS
Referring to FIGS. 1 and 2, a presently preferred
embodiment of the apparatus of the invention is shown.
This apparatus includes a motor-driven cart 10 driven by
a drive motor 12 mounted thereon. Cart 10 includes a pair
of front wheels 14 and a pair of back wheels 16 which are
interconnected by a drive shaft (not shown). A pair of
bevel gears (not shown) mounted beneath cart 10 directly
couple the drive shaft to motor 12. In an exemplary em-
bodiment, the cart 10 is 6 inches wide, 11 inches long and
6 inches high and motor 12 is a Model 41-26 electric mo-
tor manufactured by Hansen -Manufacturing Company.
Motor 12 is powered from a power source comprising
a battery pack 18 including two rechargeable nickel cad-
mium batteries which in accordance with the exemplary
embodiment under consideration are of the type manu-
factured by the Gould Company and are rated at 10 volts
D.C., 450 milliampere hours. The batteries are wired in
parallel and hence provide a total capacity of 900 mil-
liampere hours. The batteries can be held in place by a
clip (not shown) secured to cart 10 by suitable means such
as screws (not shown). In the exemplary embodiment be-
ing considered the 10 volts D.C. applied to motor 12 from
battery pack 22 provides for a maximum drive speed of 1
inch of travel in 3.3 seconds. Lower speeds can be pro-
vided by adjusting the setting of a suitable potentiometer
58 shown in FIG. 3.
Cart 10 also mounts a second, swabbing motor 20,
motor 20 being pivotably mounted in a single gimbal 22
formed by a pair of gimbal shafts 24, a portion of one of
which is shown in FIG. 2. The gimbal shafts 24 are sup-
porte by the upright flanges of a pair of L-shaped brackets
26. The horizontal flanges of brackets 26 are secured to
the upper surface of cart 10 by suitable means such as
screws 28. Motor 20 is mounted within ring or collar 30
from which gimbal shafts 24 extend and which has a
central aperture through which motor 20 extends. The
.longitudinal position of motor 20 within collar 30 can
be varied and a set screw 32 enables fixing of the posi-
tion of motor 20 within collar 30 as desired. The armature
20a of motor 20 is connected to a laterally extending elon-
gate crank arm 34, crank arm 34 including a socket 34a
in the free end thereof in which a swab S can be mounted.
Socket 34a can simply be an aperture in arm 34 which pro-
vides a friction fit with the swab S. As can best be seen in
FIG. 1, with motor 24 energized, crank arm 34 sweeps
swab S back and forth in a predetermined pattern so as to
cover or trace out a selected area. This pattern, as traced
out in India Ink on sampling surface T, is shown in FIG.
1. The movement of the swab S as dictated by crank arm
34 is a combined side to side stroke plus a spiraling action
in the Y-Z plane about the longitudinal X-axis. The
swabbing motor 20 can be a model 6907 electric motor
manufactured by Globe Industries.
An "on-off" switch 36 is mounted on the upper surface
of cart 10 near the rear thereof for controlling energiza-
tion of motors 12 and 20. A reversing switch in the form of
a micro-switch 38 located in advance of one of rear wheels
16 controls, in cooperation with an elongate actuating rod
40, reversal of the direction of movement of the cart 10.
Rod 40 is mounted for longitudinal movement in spaced
supports 42 and can be used in conjunction with an ob-
ject or obstacle 44 deliberately placed in its path to con-
trol the size of the area being sampled. More specifically,
actuator rod 40 includes an actuator cam 46 positioned at
a predetermined location along the length thereof which
controls actuation of micro-switch 38 which, in turn, as
explained hereinbelow in connection with FIG. 3, con-
trols reversing of the current through drive motor 12. The
location .of object 44 will, of course, determine when
switch 38 is actuated and, hence, the size of the area
sampled.
'In addition to the function described above, actuator
rod 40 cooperates with a lift bar 48 to pivot swabbing mo-
tor 20 so that the swab S carried by crank arm 34 is lift-
ed from the surface T. As can best be seen in FIG. 2, lift
bar 48 is L-shaped and the horizontal leg thereof is secured
5 to gimbal shaft 24. More specifically, gimbal shaft 24 is
received in a bore in this horizontal leg of bar 48 and a
set screw 32 is used to rigidly affix lift bar 48 thereto.
The vertical, downwardly depending leg of lift bar 48 is
positioned such that the lower portion thereof lies in the
10 path of actuator rod 40. Thus, when rod 40 contacts an
obstacle 44 placed in the path of movement of cart 10, rod
40 will be moved rearwardly so that cam 46 actuates
reverse switch 38 as described above and so that the end of
rod 40 engages lift bar 48, and, through the rigid con-
15 nection to gimbal shaft 24, causes pivoting of motor
20 so that swab S is lifted from the sampling surface T.
Referring to FIG. 3, the electrical control circuit for
the apparatus of FIGS. 1 and 2 is shown. As illustrated,
on-off switch 36 controls the connection of the power
20 source, represented by battery 18 and corresponding to
the battery pack described above, to drive motor 12 and
swabbing motor 20. A battery charging plug 52 can be
used in re-charging battery 18. Motors 12 and 20 are con-
nected in parallel and a diode 54 permits current flow
25 to swabbing motor 20 in one direction only. Reverse
switch 38 controls energization of a relay 56 to provide
switching of relay contacts 56R1 and 56R2. As illustrated,
with relay 56 energized the current through drive motor
12 is reversed so that the direction of movement of cart
30 10 is reversed.
It will be understood that while the invention has been
described with reference to an exemplary embodiment,
variations and modifications may be effected in the em-
bodiment without departing from the scope and spirit of
35 the invention.
What is claimed is:
1. An automatic mechanical swabbing apparatus for
microbiologically sampling surfaces using cotton swabs
comprising an independently movable transport device,
40 drive means mounted on said device for propelling said
device and swabbing means mounted on said device for
imparting a predetermined controlled swabbing motion
to a swab supported thereby during the movement of
said transport device, said transport device comprising a
45 wheeled cart and said drive means comprising a drive
motor for propelling said cart.
2. A swabbing apparatus as claimed in Claim 1 wherein
said swabbing means includes a movable crank arm in-
cluding means for detachably supporting a swab, and a
50 swabbing motor for driving said crank arm.
3. A swabbing apparatus as claimed in Claim 2 wherein
said swabbing motor imparts a circular movement to said
crank arm, said crank arm comprising an elongate crank
member affixed at end of said motor and including an
55 aperture for receiving a swab therein at the other, free
end, said crank arm imparting a combined side to side
and spiraling movement to a swab received thereby and
in contact with a sampling surface.
4. A swabbing apparatus as claimed in Claim 2 fur-
60 ther comprising pivot means for pivotably mounting
said swabbing motor on said cart.
5. A swabbing apparatus as claimed in Claim 4 wherein
said pivot means includes an annular collar for support-
ing said swabbing motor and through which said swab-
65 bing motor extends, gimbal shaft means secured to said
collar providing a pivot axis for said swabbing motor,
and bracket means for supporting said gimbal shaft
means.
6. A swabbing apparatus as claimed in Claim 5 fur-
70 ther comprising a self-contained power source mounted
on said cart for powering said drive motor and said
swabbing motor.
7. A swabbing apparatus as claimed in Claim 2. fur-
ther comprising means for automatically reversing the
75 dkection of movement of said cart.
3,841,973
i 5 6
8. A swabbing apparatus as claimed in Claim 2 fur- operative position thereof to an inoperative position so
ther comprising means for automatically lifting a swab that a swab carried by said crank arm is removed from
from the surface being sampled responsive to said cart contact with the surface being sampled.
traveling a predetermined distance.
9. A swabbing apparatus as claimed in Claim 7 where- g References Cited
in said reversing means includes an actuator rod movable UNITED STATES PATENTS
responsive to said cart traveling a predetermined dis- •>-no TCI n/im,
 n <««• ,*-,tance and means, including a microswitch actuated by 3,778,351 12/1973 Rosov 195—127
said actuator rod, for causing reversal of the direction of A T W T X T T ? T-AXICXITT^>T'T-T T> • r-
current flow through said drive motor when said micro-
 10
 ALVIN R
 TANENHOLTZ, Primary Examiner
switch is actuated. ,, o pi v
 R
10. A swabbing apparatus as claimed in Claim 9 fur-
ther comprising a lift bar pivotable responsive to said 195—120, 103.5 R
actuator rod for lifting said swabbing motor from the


Apparatus for microbiological sampling

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