Method of selectively shaping hollow fibers of heat exchange catheter

A group of multiple hollow fibers may be shaped to introduce angular divergence among the fibers, or to introduce a selected longitudinal oscillation into the fibers. In one shaping technique, the fibers are held in parallel while upper and lower crimping assemblies of parallel crimping bars are drawn together on opposite sides of the parallel fibers. When bars of the opposing assemblies draw sufficiently close, they sandwich the fibers in between them, causing each fiber to assume a shape that oscillates as the fiber repeatedly goes over and then under successive bars. Since the crimping bars are aligned at oblique angles to the fibers, the peaks and troughs of successive fibers are offset. While in this position, the fibers are heated and then cooled to permanently retain their shapes. A different shaping technique utilizes a lattice of crisscrossing tines defining multiple apertures. In this technique, the lattice and fibers are positioned so that each fiber passes through one of the apertures. Then, the lattice and/or the fibers are slid apart or together until the lattice holds the fibers in a desired configuration, where the fibers have a prescribed outward divergence relative to each other. While in this position, the fibers are heated and then cooled to permanently retain this angular divergence.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to catheters that utilize a bundle of many 
small fibers to conduct heat or materials exchange with a target area of 
the human body. More particularly, the invention concerns a catheter 
manufacturing process that selectively shapes a group of multiple hollow 
fibers to introduce angular divergence among the fibers or to introduce a 
selected longitudinal oscillation into the fibers. 
2. Description of the Related Art 
In warm blooded creatures, temperature regulation is one of the most 
important functions of the body. Despite the known importance of properly 
maintaining body temperature, scientists have discovered certain 
beneficial effects of artificially inducing a hypothermic state. For 
instance, cooling the body can help regulate vital functions during 
surgery by lowering the metabolism. With stroke, trauma, and other 
pathological conditions, hypothermia is believed to also reduce the 
permeability of the blood/brain barrier. Induced hypothermia is believed 
to additionally inhibit the release of damaging neurotransmitters, inhibit 
calcium mediated effects, inhibit brain edema, and lower intra cranial 
pressure. Regardless of the particular mechanism, the present invention 
understands that fevers degrade the outcomes for patients suffering from 
brain trauma or stroke, and moreover that hypothermia can improve the 
outcomes for such patients. 
Hypothermia may be induced locally or systemically. With local hypothermia, 
physicians focus their cooling efforts on a particular organ, limb, 
anatomical system, or other region of the body. With systemic hypothermia, 
doctors universally lower body temperature without particular attention to 
any body part. 
Under one technique for inducing systemic hypothermia, physicians cool the 
patient's entire body by packing it in ice. Although this technique has 
been used with some success, some physicians may find it cumbersome and 
particularly time consuming. Also, it is difficult to precisely control 
body temperature with ice packing. As a result, the patient's body 
temperature overshoots and undershoots the optimal temperature, requiring 
physicians to add or remove ice. Furthermore, there is some danger of 
injuring the skin, which is necessarily cooled more than any other body 
part. 
In another approach to systemic hypothermia, the patient is covered with a 
cooling blanket, such as an inflatable air- or water-filled cushion. 
Beneficially, cooling blankets offer improved temperature control because 
physicians can precisely regulate the temperature of the inflation medium. 
Nonetheless, some delay is still inherent, first for a cooling element to 
change the temperature of the cooling medium, and then for the temperature 
adjusted cooling medium to cool the desired body part. This delay is even 
longer if the targeted body part is an internal organ, since the most 
effective cooling is only applied to the skin, and takes some time to 
successively cool deeper and deeper layers within the body. 
The present invention recognizes that a better approach to inducing 
hypothermia is by circulating a cooling fluid through a cooling catheter 
placed inside a patient's body. The catheter may be inserted into veins, 
arteries, cavities, or other internal regions of the body. The present 
assignee has pioneered a number of different cooling catheters and 
techniques in this area. Several different examples are shown U.S. 
application Ser. No. 09/133,813, entitled "Indwelling Heat Exchange 
Catheter and Method of Using Same," filed on Aug. 3, 1998. Further 
examples are illustrated in U.S. application Ser. No. 09/294,080 entitled 
"Catheter With Multiple Heating/Cooling Fibers Employing Fiber Spreading 
Features," filed on Apr. 19, 1999. The foregoing applications are hereby 
incorporated into the present application by reference. These applications 
depict catheters where the tip region includes multiple hollow fibers. The 
fibers carry a coolant that is circulated through the catheter. The thin 
walls and substantial surface area of the fibers are conductive to the 
efficient transfer of heat from surrounding body fluids/tissue to the 
coolant, thereby cooling the patient. 
Advantageously, cooling catheters are convenient to use, and enable doctors 
to accurately control the temperature of a targeted region. In this 
respect, cooling catheters constitute a significant advance. This 
invention addresses improvements related to such catheters. 
SUMMARY OF THE INVENTION 
Broadly, the present invention recognizes that wider spatial distribution 
of heat exchange fibers in a catheter increases the catheter's rate of 
heat exchange. The approach of this invention may also be applied in areas 
other than heat exchange, such as materials exchange (e.g., the exchange 
of oxygen or another gas with surrounding blood or other liquid). 
To achieve wider fiber distribution, the present invention introduces 
techniques to selectively shape hollow fibers. Shaping may be performed to 
introduce divergence ("splay") among the fibers, or alternatively to 
introduce a selected longitudinal oscillation into the fibers. In one 
shaping technique, the fibers are held in parallel while opposing 
assemblies of parallel crimping bars are drawn together on opposite sides 
of the parallel fibers. When bars of the opposing assemblies draw 
sufficiently close, they sandwich the fibers in between them, causing each 
fiber to assume a shape that oscillates as it repeatedly goes over and 
then under successive bars. The crimping bars are alligned at oblique 
angles to the fibers; thus, the peaks and troughs of each fiber are offset 
from every other fiber. While in this position, the fibers are heated and 
then cooled to permanently establish their shapes. Or, shape 
irregularities can be introduced into the fibers during fabrication when 
the fibers are malleable by directing air or objects against the fibers. 
A different shaping technique utilizes a lattice of crisscrossing tines 
defining multiple apertures. In this technique, the lattice and fibers are 
arranged so that each fiber passes through one of the apertures. Then, the 
lattice and/or the fibers are slidably repositioned until the lattice 
holds the fibers with a prescribed outward divergence relative to each 
other. While in this position, the fibers are heated and then cooled to 
permanently retain this shape. 
In one embodiment, the invention may be implemented to provide a method to 
shape a group of hollow fibers. In a different embodiment, the invention 
may be implemented to provide an apparatus such as a group of hollow 
fibers formed with the foregoing method, or a catheter with such a group 
of fibers. 
The invention affords its users with a number of distinct advantages. For 
example, in comparison with conventional multi-fiber catheters, catheters 
of this invention exchange heat or materials with improved efficiency 
because the fibers are more thoroughly separated from each other. Either 
by splaying fibers away from each other, or by creating fibers that 
oscillate with a staged phase delay, the invention encourages fiber 
spreading. This helps avoid the creation of a common boundary layer among 
several fibers, since the fibers are more likely to be spread apart. The 
invention also provides a number of other advantages and benefits, which 
should be apparent from the following description of the invention.

DETAILED DESCRIPTION 
The nature, objectives, and advantages of the invention will become more 
apparent to those skilled in the art after considering the following 
detailed description in connection with the accompanying drawings. As 
mentioned above, the invention concerns techniques for selectively shaping 
hollow fibers designed to exchange heat or materials with body 
fluids/tissue. As examples, hollow fibers are discussed herein, even 
though the fiber shaping techniques of this invention are similarly 
applicable to solid fibers. These techniques may be applied to introduce 
divergence among fibers in a bundle as the fibers exit a common point of 
attachment, or alternatively to introduce a selected longitudinal 
oscillation into the fibers. 
Fiber Splaying 
Introduction 
FIG. 1 shows a sequence 100 to illustrate one example of the method aspect 
of the present invention. For ease of explanation, but without any 
intended limitation, the example of FIG. 1 is described in the context of 
various hardware components shown in FIGS. 2-6 and described below. 
Obtaining Fiber Bundle 
The sequence 100, which starts in step 102, describes a process of shaping 
fibers to introduce a prescribed divergence as the fibers exit from a 
common source of attachment. In step 104, a fiber bundle is obtained, 
which includes fibers stemming from a common attachment point at a distal 
end of a device such as a catheter 200, shown in FIG. 2. In this example, 
the fibers 202 proceed outward from a fluid transfer housing 204 located 
at the distal end of a catheter 200. The fibers 202 are collectively 
called a "bundle." Since they are not bound at their distal ends, the 
fibers are called "free tip." 
When the catheter is assembled, the housing 204 is coupled to a 
supply/return assembly 206 that includes supply and return conduits for 
circulating a fluid to/from the fibers 202. The supply/return assembly may 
comprise, for example, parallel or concentric fluid passageways. The 
housing 204 contains paths directing pre-circulation fluid from the supply 
conduit to the fibers, and other paths routing post-circulation fluid 
received from the fibers to the return conduit. In the example of FIG. 2, 
each fiber houses separate outward and inward fluid paths. 
In one example, the fibers are non-porous and the fluid is a coolant such 
as water, saline, etc., used to cool blood, tissue, or other material that 
surrounds the catheter 200 while in use. In this embodiment, the entire 
catheter, including the fibers, is sealed to prevent any exchange of 
coolant with the body tissue or fluid surrounding the catheter. In another 
example, the catheter 200 contains oxygen, medicine, or another 
circulating substance that is distributed into surrounding blood, tissue, 
or other material surrounding the catheter 200 through tiny pores (not 
shown) in the fibers 202. 
In contrast to the free tip fibers shown in FIG. 2, the invention may be 
applied to other fiber arrangements, such as fibers that are distally 
joined ("bound tip"), or fibers that individually proceed outward and 
return back to the fluid transfer housing ("looped fibers") to provide a 
unidirectional fluid path. Further details of catheters and fiber bundles 
are explained in the patent applications identified above and incorporated 
by reference. 
Obtaining Lattice 
In addition to the fiber bundle, step 104 also obtains a fiber positioning 
lattice. FIG. 3 shows an exemplary one-piece lattice 300. The lattice 300 
is a planar structure that includes horizontal tines 302 and vertical 
tines 304 that criss-cross each other, forming apertures 306 between the 
tines 302, 304. In one example, the tines are spaced by approximately one 
millimeter, and comprise a non-abrasive material such as plastic, 
stainless steel, etc. 
As an alternative to the one-piece lattice 300 of FIG. 3, a multi-part 
lattice 400 may be used as shown in FIG. 4. The multi-part lattice is 
especially useful for bound tip fiber bundles or looped fibers. The 
lattice 400 includes first 402 and second 404 spacing assemblies. The 
spacing assemblies 402, 404 include respective sets of substantially 
parallel tines 406, 408, thereby forming comb-like shapes. The spacing 
assemblies 402, 404 may be slid together at right angles until they 
overlap and form a nearly planar structure like the lattice 300. In this 
overlapping configuration, the crisscrossing tines 406, 408 define 
apertures (not shown) such as those apertures 306 in the lattice 300. 
Positioning Lattice and Fiber Bundle 
After step 104, the fibers and desired lattice (300 or 400) are positioned 
such that each fiber passes through one of the lattice's apertures (step 
106). In the case of the lattice 300, step 106 involves individually 
routing each fiber's distal end through one of the lattice apertures 306. 
In the case of the lattice 400, step 106 is performed by (1) sliding the 
spacing assembly 402 toward the fiber bundle so that free ends of the 
tines 406 pass into the fiber bundle 202 with individual fibers passing 
into the spaces between adjacent tines 406, and (2) sliding spacing 
assembly 404 into the fiber bundle 202 at a right angle to the spacing 
assembly 406. The assemblies 402, 404 may be brought together at another 
angle than perpendicular, however, recognizing that if the angle is too 
large or small the resultant apertures may be too long to hold the fibers 
in position. 
FIG. 5 shows some fibers 500 after insertion into the lattice 300, after 
completion of step 106. The fibers 500 only represent some of the fibers 
202, as the remaining fibers (which would appear in the middle of the 
lattice) are omitted from this drawing to enhance clarity and reduce 
clutter. 
Adjusting Divergence 
After step 106, step 108 is performed to adjust the divergence among the 
fibers, now routed through the lattice 300. FIG. 6 illustrates fiber 
divergence, also called "splay." Each fiber, such as the fiber 600, exits 
from the fluid transfer housing 204 at an exit point 604. Without any 
fiber divergence, the fibers would proceed outward from the housing 204 in 
a direction largely parallel to the longitudinal axis of the catheter 602. 
Namely, the fiber 600 would proceed outward from its exit point 604 along 
a line 606. 
Step 108 adjusts fiber divergence by sliding the positioning lattice toward 
or away from the housing 204. When the lattice is moved toward the housing 
204, the fiber 600 is bent outward from its normal path 606, increasing 
its divergence angle 608. Conversely, when the lattice is moved away from 
the housing 204, the fiber is not bent outward so much, decreasing its 
divergence angle 608. Consequently, step 108 involves sliding the lattice 
along the fibers (or vice versa) until the desired divergence angles are 
attained. 
Heating & Cooling 
At the conclusion of step 108, the fibers are held in their desired 
positions. To fix this position, the fibers (while held in place by the 
lattice) are heated to a prescribed temperature (step 110). This 
temperature is sufficiently high to reach a "fixing temperature" at which 
the fibers will retain their current shape even after the fibers cool. 
This varies according to the materials used. However, in the example of 
polyurethane fibers, step 110 may be performed using an oven to heat the 
fibers to about 180.degree. F. for about one hour. 
After step 110, step 112 cools the fibers. This may be achieved at a slower 
pace by permitting the structure to cool off at room temperature, or more 
quickly by immersing the fibers and their positioning lattice in a cool 
water bath. As an alternative to steps 110-112, the fiber shaping steps 
106-108 may be performed during fiber fabrication, when the fibers are 
malleable. 
Removing Lattice 
After the fibers cool below their fixing temperature, the lattice is 
removed in step 114. Despite removal of the positioning lattice, the 
fibers retain their shape because of the heat fixing performed in step 
110. After step 114, the fiber shaping is concluded and the routine 100 
ends in step 116. Subsequent steps (not shown) are then performed to 
construct and assemble the remainder of the catheter. 
Oblique Fiber Crimping 
Introduction 
FIG. 7 shows a sequence 700 to illustrate another example of the method 
aspect of the present invention. For ease of explanation, but without any 
intended limitation, the example of FIG. 7 is described in the context of 
the hardware components of FIGS. 8-11, as described below. The sequence 
700, which starts in step 702, describes a process of shaping fibers to 
give the fibers a prescribed, periodic waviness. The fibers are placed 
side-by-side during shaping. From one fiber to the next, the peaks and 
troughs are successively delayed by a prescribed amount as a result of 
this procedure. Thus, the waveforms defined by the fibers are out of phase 
with each other. Alternatively, the waveforms may be irregular (i.e., 
non-periodic) if desired. 
In the context of heat exchange catheters, the fibers comprise hollow, 
non-porous fibers such as polyurethane. In another example, the catheter 
may contain oxygen, a medicine, or another circulating substance that is 
exchanged with surrounding blood, tissue, or other material surrounding 
the catheter through tiny pores (not shown) in the fibers. 
In step 704, retaining structures are used to hold the fibers in parallel. 
Although the fibers may already be mounted to a catheter prior to step 
704, this step is more advantageously applied to unattached fibers, which 
are more conveniently laid in parallel with each other. 
FIG. 8 shows one technique for holding fibers 800 in parallel, using 
retainers 802, 804. Each retainer 802, 804 is a two-piece assembly, having 
respective top members 802a, 804a and bottom members 802b, 804b. Top and 
bottom retaining members are held firmly together by structure discussed 
in greater detail below. In this configuration, the fibers 800 
collectively form a ribbon shape having a top side 806 and a bottom side 
808. 
FIGS. 8A-8B further illustrate some exemplary retainers. The retainer 820 
(FIG. 8A) includes top and bottom members 822, 824 connected at a hinge 
823. Opposite the hinge, the members 822, 824 may be clamped, bound, or 
otherwise fastened together to firmly hold fibers in between. The hinge 
823 is merely one embodiment, and ordinarily skilled artisans (having the 
benefit of this disclosure) will recognize many other means for holding 
the top and bottom members 822, 824 together to sandwich the fibers in 
between. 
The member 822 defines a series of grooves 826 to facilitate more 
convenient, even, and definitive distribution of fibers along the entire 
length of the retainer, with each fiber nestling into one groove. Opposite 
the grooves 826, the member 824 may optionally define a series of 
complementary teeth 828 to firmly hold each fiber in its respective 
groove. 
The retainer 830 (FIG. 8B) also includes top and bottom members 832, 834. 
Though shown connected at a hinge 833, fastening of the members 832, 834 
may be adapted in similar fashion as the retainer 820. Each member 832, 
834 includes a supple gripping surface 836, 838, such as rubber, foam, or 
another firm but pliable substance for holding the fibers in place. 
In addition to the embodiments 820, 830, ordinarily skilled artisans 
(halving the benefit of this disclosure) will understand that the 
invention further contemplates an extensive variety of non-disclosed 
retainers. One example is a hybrid combination (not is shown) of the 
retainers 820, 830, etc. 
As another example (not shown), the proximal retainer may be constructed as 
shown above, with the distal retainer being a series of parallel posts. 
This embodiment is useful when each fiber comprises a loop that proceeds 
outward and loops back to its point of origination. The distal, looped 
ends of the fibers are retained by routing the fibers around respective 
posts of the distal retainer. 
Placing Crimping Assemblies Above/Below Fibers 
With the retainers holding the fibers in parallel after step 704, step 706 
then prepares for crimping of the fibers using crimping assemblies, the 
structure of which is discussed below. Namely, step 706 places one 
crimping assembly above the fibers, and one crimping assembly below the 
fibers. FIG. 9 shows an exemplary crimping assembly 902 above the fibers 
900 (omitting the crimping assembly beneath the fibers 900, for clarity of 
illustration). The crimping assembly 902 above the fibers is referred to 
as an "upper" crimping assembly, whereas the other crimping assembly (not 
shown) is referred to as the "lower" crimping assembly. These terms are 
used merely for explanation and clarity of description, however, and terms 
such as "upper," "lower," and the like may be reversed without 
substantively changing their meaning. 
Each crimping assembly includes a series of substantially parallel crimping 
bars, such as the bars 904 of the assembly 902. The size and spacing of 
the bars is selected depending upon factors such as the fiber diameter, 
fiber material, desired crimping pattern, etc. Although other arrangements 
may be used, the bars of the upper crimping assembly may be substantially 
equidistant, as with the bars of the lower crimping assembly. Furthermore, 
the distance between bars in the upper crimping assembly may be the same 
(or different) than the distance between bars in the lower crimping 
assembly, depending on the desired shape of post-crimping fibers. 
The distance between adjacent crimping bars (measured center-to-center) 
defines the span between adjacent peaks and troughs in a fiber, i.e., 
one-half of the fiber's wavelength. The space between adjacent crimping 
bars is necessarily greater than the fiber diameter, to permit the fibers 
to run between the bars. 
As am example, the crimping bars 904 may be mounted in position by a base 
member (not shown) secured to one end of each bar 904. One advantage of 
this single-base-member arrangement is that the crimping assemblies may be 
interleaved by positioning their base members toward the outside, with the 
bars' open ends coming together. Alternatively, two base members may be 
used for each crimping assembly, where one base member spans one end of 
the bars 904, and another base member spans the opposite end of the bars 
904. 
FIG. 9A provides a cross-sectional depiction of a different example, which 
permits the bars of the two crimping assemblies to be brought together and 
actually past each other to cause a more drastic crimp. In this example, 
the bars of each crimping assembly are held in position by a base member 
that is offset from the axes of the bars. More particularly, the crimping 
assembly 950 includes bars 956 mounted to an offset base member 951; 
similarly, a crimping assembly 952 includes bars 957 mounted to an offset 
base member 953. With this arrangement, the bars 956, 957 may be brought 
into alignment with each other by urging the base members 951, 953 
together; moreover, by continuing this motion one set of bars may actually 
be driven past the other set of bars to provide an exaggerated crimping 
configuration. 
Aligning Crimping Assemblies 
After step 706, the upper and lower crimping assemblies are aligned so that 
bars of the upper and lower assembly are substantially parallel to each 
other, and so that the parallel bars form an oblique angle to the parallel 
fibers. After crimping, the place where each bar contacts a fiber will 
provide a peak or trough in an oscillating pattern along the length of the 
fiber. Namely, the bars of one crimping assembly will define all fiber 
peaks, with the bars of the other crimping assembly defining all troughs 
(or vice versa). Step 708 reduces the likelihood that any two fibers reach 
their peaks and troughs at the same position along their lengths. This is 
the reason for the oblique alignment of bars with the fibers. To 
illustrate this in more detail, the bars are positioned so that the angle 
980 (FIG. 9) formed with the fibers is neither 0.degree., 90.degree., 
180.degree., nor 270.degree.. In other words, the angles that the bars 
form with respect to the fibers are oblique, i.e., neither parallel nor 
perpendicular. 
Equation 1 shows an exemplary computation of the angle 980. 
EQU angle 980=tan.sup.-1 (x.multidot.n/.lambda.) [1] 
where: 
x=the distance between adjacent fibers. 
n=the number of fibers. 
.lambda.=the desired fiber wavelength, i.e., distance between successive 
peaks or troughs in one fiber. 
Equation 1 computes the angle 980 such that, during the span of one fiber 
wavelength, all fibers successively reach their peak height, with none 
repeating. Ordinarily skilled artisans (having the benefit of this 
disclosure) will recognize a variety of other techniques for computing the 
angle 980, further description being unnecessary to the present 
disclosure. 
Drawing Crimping Assemblies Together 
After the alignment of step 708, step 710 draws the upper and lower 
crimping assemblies together. The relative distance between the upper and 
lower crimping assemblies is reduced until the fibers bend into 
oscillating shapes that repeatedly curve back and forth longitudinally 
along the fibers, as the fibers pass around bars of the upper and lower 
assemblies in alternating fashion. FIG. 10A shows one example, where a 
fiber 1000 is being crimped between bars 1002 of an upper crimping 
assembly and bars 1004 of a lower crimping assembly. If desired, the 
crimping assemblies may be drawn past each other to achieve exaggerated 
crimping as shown in FIG. 10B. 
If desired, step 710 may adjust tension on the fibers by changing the 
distance between the retainers (e.g., 802, 804 of FIG. 8) that hold the 
opposite ends of the fibers. Decreasing this distance releases strain on 
the fibers as the crimping assemblies re-route the fibers into a path that 
is longer then the straight distance between the fibers' ends due to the 
paths' repeated curves. Otherwise, without any narrowing of the retainers, 
the fibers may be excessively stretched or sheared while the crimping 
assemblies force the fibers to assume a longer, curving path. During step 
710, the tension across the fibers may be selectively adjusted to form 
tighter crimps and a more triangular fiber oscillation (using more 
tension), or alternatively looser crimps with a more sinusoidal 
oscillation (using less tension). 
Heating & Cooling 
With the crimping assemblies sandwiching and effectively crimping the 
fibers as discussed in step 710, this configuration is held while the 
fibers are heated (step 712). The fibers are heated to a fixing 
temperature, causing the fibers to permanently maintain their crimped 
shape, despite subsequent cooling. This temperature varies according to 
the materials used. In the example of polyurethane fibers, step 712 may 
involve placing the fibers, retainers, and crimping assemblies into an 
oven and heating at 180.degree. Fahrenheit for about one hour. After step 
712, while still holding the fibers in their crimped position, the fibers 
are cooled (step 714). The fibers may be cooled by various techniques, 
such as removing them from the oven and letting them cool to room 
temperature, immersing the fibers in water or another cooling liquid, etc. 
During cooling, the fibers are still held in crimped form by the retainers 
and crimping assemblies to ensure that they cool beneath the fixing 
temperature while held in the desired position. 
Removing Crimping Assemblies 
After cooling, step 716 removes the crimping assemblies and retainers. Due 
to the heat shaping previously described, the fibers retain their crimped 
shape despite removal of the crimping assemblies. As a practical matter, 
the crimping assemblies may be removed earlier if desired, as long as the 
fibers have cooled sufficiently that they are no longer amenable to heat 
shaping. 
After completing the sequence 700, fibers remain crimped as shown by FIG. 
11. Namely, each of the fibers 1100 oscillates sinusoidally along its 
length, presenting a series of troughs (such as 1104) and peaks (such as 
1102). No two fibers reach a peak or trough at the same point. Instead, 
the fibers 1100 reach their peaks and troughs in successive order from the 
top of the page down, as viewed in FIG. 11. The fibers' peaks are aligned 
along lines such as the line 1106, the line 1108, etc. 
OTHER EMBODIMENTS 
While the foregoing disclosure shows a number of illustrative embodiments 
of the invention, it will be apparent to those skilled in the art that 
various changes and modifications can be made herein without departing 
from the scope of the invention as defined by the appended claims. For 
example, the present crimping fixture can be established by plural 
grooves, each describing a predetermined waveform different from the outer 
grooves, with fibers having mandrels inside being laid in the grooves and 
then heat treated as aggregate to cause the fibers to permanently assume 
the shapes of the respective grooves. Furthermore, although elements of 
the invention may be described or claimed in the singular, the plural is 
contemplated unless limitation to the singular is explicitly stated.