U.S. patent number 3,579,810 [Application Number 04/833,056] was granted by the patent office on 1971-05-25 for method of making capillary assemblies for oxygenators and the like.
This patent grant is currently assigned to N/A. Invention is credited to George Mon.
United States Patent |
3,579,810 |
Mon |
May 25, 1971 |
METHOD OF MAKING CAPILLARY ASSEMBLIES FOR OXYGENATORS AND THE
LIKE
Abstract
An inexpensive and rapid method of assembling capillary units
and the like is disclosed. Commercially available capillary tubing
is first wound around two end pins spaced apart a predetermined
distance slightly greater than the length of the capillary strands
in the completed unit. Each end pin is then dipped into an epoxy
potting compound and caused to harden. The hardened ends are
thereafter cut in appropriate places so as to expose the capillary
tubes. A suitable outer housing, having appropriate conduits for
the transfer of blood and oxygen to the unit, may then be provided
to the assembled capillaries.
Inventors: |
Mon; George (Silver Spring,
MD) |
Assignee: |
N/A (N/A)
|
Family
ID: |
25263298 |
Appl.
No.: |
04/833,056 |
Filed: |
June 13, 1969 |
Current U.S.
Class: |
29/527.1; 422/45;
264/277 |
Current CPC
Class: |
B01D
63/021 (20130101); Y10T 29/4998 (20150115) |
Current International
Class: |
B01D
63/02 (20060101); B23p 017/00 (); B23p
025/00 () |
Field of
Search: |
;29/527.1 ;23/258.5
;264/277,317 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Campbell; John F.
Assistant Examiner: DiPalma; Victor A.
Claims
I claim:
1. A method of assembling a capillary unit comprising:
a. winding a continuous strand of capillary tubing around two pins
spaced-apart a predetermined distance;
b. maintaining each pin in a potting compound;
c. causing the potting compound to harden;
d. cutting the hardened potting compound so as to expose a
plurality of open ended capillary tubes while at the same time
providing a rigid portion holding said ends in fixed relation to
each other; and
e. providing conduit means for transferring appropriate fluids to
the capillary unit.
2. The method of claim 1 wherein the pins are spaced-apart a
distance slightly greater than the desired length of capillary
tubing in the completed capillary unit.
3. The method of claim 2 wherein the pins are located on a winding
unit having means to rotate the pins and means to adjust the
distance between the pins.
4. The method of claim 3 wherein the pins are detachable from the
winding unit.
5. The method of claim 1 wherein the potting compound comprises a
resinous epoxy material capable of being hardened.
6. The method of claim 1 wherein the step of hardening the potting
compound includes the step of applying heat to the compound.
7. The method of claim 1 further comprising the steps of placing
each pin into a mold having a cavity therein and pouring the
potting compound into the cavity.
8. The method of claim 7 further comprising the steps of inserting
a predetermined number of rods into the potting compound prior to
hardening so as to provide preformed holes in said rigid portion to
be used for securing each end of the capillary unit to an external
housing.
Description
RIGHTS OF GOVERNMENT
The invention described herein may be manufactured, used, and
licensed by or for the U.S. Government for governmental purposes
without the payment to me of any royalty thereon.
BACKGROUND OF THE INVENTION
This invention relates to a capillary assembly unit and, in
particular, to a method of forming the two ends of such a unit.
A typical capillary unit used as an oxygenator is disclosed by De
Wall in U.S. Pat. No. 2,972,349, issued Feb. 21, 1961. Generally
such a unit comprises a rectangular box having a plurality of thin
capillary tubes connected between the two end walls of the unit.
Blood is transmitted from one end wall to the other through the
capillary tubes while oxygen is transmitted into the rectangular
box and caused to completely surround the blood-containing
capillary tubes. Oxygenation of the blood occurs in a well-known
manner as described in the De Wall patent. The materials of which
the capillary tubes are formed must be permeable to the
transmission of both oxygen and carbon dioxide while being
impermeable to blood. A silicone rubber known as Silastic is
commonly used for this purpose, although other plastic materials
have been known to be useful.
Because of the numerous capillaries required to make up a typical
capillary unit, ordinarily between 500 and 2,000 capillaries, the
manufacture of such units is a tedious task. Previously such units
have been manufactured by drilling or otherwise forming thousands
of tiny holes of the appropriate diameter in the end walls of the
unit, and then individually inserting the capillary tubes, each cut
to its appropriate length, into each of the holes. Obviously this
method of manufacture requires many hours of tedious labor, and the
cost of manufacturing such units increases significantly with the
number of man-hours required.
It is, therefore, a primary object of this invention to provide an
inexpensive, rapid, and reliable method of manufacturing capillary
units.
A further object of this invention is to eliminate the need for
preforming capillary holes in each of the two end walls of the
unit.
Still another object of the invention is to eliminate the need for
individually inserting each of the capillary tubes into each
preformed capillary hole.
A further object of the invention is to eliminate the need for
individually measuring and cutting each capillary tube to its
required length.
These and other objects of the invention will become more apparent
from the following description of the invention.
SUMMARY OF THE INVENTION
Briefly, in accordance with this invention, a capillary unit is
made by first winding many turns of commercially available Silastic
tubing onto a winding unit. The winding unit comprises a pair of
guide pins which are spaced-apart a predetermined distance to
provide for the desired length of tubing. After a sufficient number
of strands have been wound on the winding unit, the capillary
tubes, together with the two guide pins, are removed from the
winding unit and each end is inserted into the cavity of a mold.
The mold is filled with Silastic or epoxy potting compound so as to
completely surround the tubing together with the guide pin. The
potting compound is caused to harden and is then removed from the
mold and cut in the appropriate place so as to expose the ends of
each of the capillary tubes. This operation is repeated at both
ends of the tubing.
Thereafter, only the sidewalls as well as the appropriate means for
providing the gas and blood inputs need to be put in place for a
completed oxygenator unit.
BRIEF DESCRIPTION OF THE DRAWINGS
The specific nature of the invention as well as other objects,
aspects, uses, and advantages thereof will clearly appear from the
following description and from the accompanying drawings, in
which:
FIG. 1 is a front cross-sectional view of a completed oxygenator
unit made in accordance with this invention.
FIG. 2 is a perspective view of the winding unit used in accordance
with the teachings of this invention.
FIG. 3 is a front cross-sectional view of the mold used to
manufacture the two ends of the oxygenator unit in accordance with
this invention.
FIGS. 4 and 5 are cross-sectional views of one end of the
oxygenator unit after it has been removed from its mold.
FIG. 6 is an enlarged cross-sectional view of one end of the
oxygenator unit.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawings, FIG. 1 shows oxygenator unit 10
having blood inlet means 11 and blood outlet means 12, as well as
oxygen inlet means 13 and carbon dioxide outlet means 14. Blood
entering inlet means 11 is forced into capillary tubes 15 by means
of open ends 16. The blood travels through capillary tubes 15,
exiting at open ends 17, and leaves the oxygenator unit by means of
outlet conduit 12. Oxygen gas is transmitted through inlet conduit
13 and completely surrounds blood-containing capillary tubes 15.
Because the capillary tubes are permeable to gases, blood in the
capillary tubes is oxygenated and carbon dioxide given off. The
carbon dioxide leaves the oxygenator unit by means of outlet
conduit 14. Capillary tubes 15 are held in place at both ends by
means of epoxy resin blocks 18 and 19, which are secured to the
outer walls of oxygenator unit 10 by means of bolts 20. An enlarged
fragmentary view of capillary tubes 15 is shown in FIG. 6.
FIG. 2 shows the first step involved in manufacturing an oxygenator
unit in accordance with this invention. Because capillary tubing is
commercially available in long continuous rolls, advantage is taken
of this fact by continuously winding the tubing many times around a
winding unit such as that shown in FIG. 2. The winding unit
comprises a base 23 which supports a vertical column 24 having
thereon a horizontal rotatable shaft 26. Shaft 26 is rotated by
means of handle 25 and supports an arm 27 securely mounted at right
angles to shaft 26. At the two extreme ends of arm 27 are securely
mounted two short horizontal bars 28 and 29. Bars 28 and 29 are
adjustable along the length of arm 27 so as to provide a desired
length of tubing. Connected to bars 28 and 29 by means of threaded
screws 32 and 33 are a pair of pins 31 and 30. Capillary tubing is
wound around pins 31 and 30 as many times as necessary, usually
several hundred or more loops, in order to obtain the desired
number of capillary tubes necessary for the oxygenator unit. After
the winding process, tubing 15 is tied at one or two places by
clamps 34 and 35. Pins 30 and 31 are then removed from the winding
unit and each end is sequentially dipped into epoxy potting
compound as will be further described with respect to FIG. 3.
FIG. 3 is a front cross-sectional view of a mold 36 having therein
a cavity 38. Mold 36 is securely held together by means of bolts or
screws which fit into holes 37. By removing the securing means in
holes 37 the mold can be opened up so as to insert end pin 30 into
appropriate slots 39 and 40. After pin 30 together with capillary
winding 15 is inserted and secured into slots 39 and 40, cavity 38
is filled with epoxy potting compound 45. Any known commercially
available potting compound may be used. Typically GE-RTV 615 has
been used satisfactorily in this invention. While the compound is
still in its liquid condition, rods 42 and 43 are inserted into
appropriate places in mold 36 for a purpose which will be
hereinafter described.
In order to shorten the curing and hardening time of the epoxy
compound, mold 36 is placed on a hot plate and cured for about
11/2hours at approximately 250.degree. F.
After the epoxy compound has sufficiently hardened, it may be
removed from mold 36 and will appear as shown in FIG. 4. The bottom
portion of the hardened mold is then cut off with a sharp
instrument and discarded as shown in FIG. 5, leaving only the top
portion which will constitute end block 19 of oxygenator unit 10.
Rods 42 and 43 as shown in FIG. 4 can be easily be removed, thereby
leaving preformed holes 46 and 47 for receiving bolts 20 as shown
in FIG. 1.
It should be apparent that the entire process an be performed
rapidly and efficiently by unskilled operators. The process is also
readily adaptable to assembly line techniques.
Example
An oxygenator unit was constructed in accordance with this
invention by providing 500 windings of Silastic tubing around the
winding unit, and dipping each end of the tubing into the cavity of
a molding unit such as shown in FIG. 3. The unit was filled with
about 165 mg. of Silastic resin GE-RTV 615, and cured at
250.degree. F, for about 11/2hours.
It will be appreciated that the embodiment described herein is only
exemplary, as many modifications could be made within the spirit
and scope of this invention. For example, the winding unit need not
be as shown and, in fact, may be replaced by two guide pins
securely held in some appropriate place at a predetermined
spaced-apart distance. The winding unit need not be rotatable as it
would be a simple matter to wind capillary tubing around the ends
of two stationary guide pins. Oxygenator unit 10 also need not be
as shown, for it may, if desired, be constructed completely of
plastic material in a single unitary structure. The method can be
used to assemble capillary units other than oxygenators. For
example, extracorporeal circulation systems for assisting the
functions of the heart, kidney and lungs may be assembled in
accordance with this invention.
I wish it to be understood that I do not desire to be limited to
the exact details of construction shown and described, for obvious
modification will occur to persons skilled in the art.
* * * * *