Note: Descriptions are shown in the official language in which they were submitted.
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Background of the Invention
1. Field of the Invention:
The present invention relates to processes and devices for
determining the rheological properties of fluids and, more
particularly, to the estimation of differential rheological
properties of heterogeneous fluids, particularly biological fluids
such as saliva, ejaculates, cervical mucus and blood. Such fluids
usually are composed of several liquid fractions of different
chemical compositions, molecular weights and rheological properties.
2. The Prior Art:
The determination of rheological properties of such
heterogeneous fluids has been difficult because: (1) random
structural variations from sample to sample complicate efforts to
obtain reproducible values; (2) collection and testing of a sample
can cause significant changes in its visco-elastic structure; (3)
conditions in the test instrument are different from conditions in-
vivo or in-situ; (4) particular measurements do not necessarily
indicate particular visco-elastic structures; and (5) comparative
standards of known visco-elastic structures generally are lacking.
In particular, present on-the-spot testing techniques are inadequate.
Summary of the Invention
The primary object of the present invention is to provide
processes and devices, for testing fluids having high and low
viscosity components, characterized by disposing a sample of such
fluid in a test region between a pair of bearing members which are
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biased for relative motion and which are characterized by at least
one porous bearing surface. Certain of the low viscosity components
are absorbed by the porous bearing surface. Certain of the high
viscosity components remain in the test region to establish
characteristics, which are indicated by the relative motion between
the bearing members. The rheological properties of these high
viscosity components are a function of these characteristics. In
one embodiment, the bearing members are cylindrical and one of the
bearing members is provided with a port through which a predetermined
amount of sample fluid can be introduced into the test region between
the bearing surfaces under standardized shear conditions. In another
embodiment, the bearing membèrs are reciprocable, being provided
with discrete parallel ridges or flutes, the outermost portions of
which define ridge lines, the ridges of one bearing member being
crossed with respect to the ridges of the other, the test region
between the bearing surfaces being a tear region. The present
invention takes advantage of the fact that, from a practical (rather
than a purely scientific) standpoint, it frequently i9 not necessary
to measure exact rheological values of some fluids in order to yield
technically significant information.
Other objects of the present invention in part will be
obvious and in part will appear hereinafter.
The invention accordingly comprlses the products and
processes, together with their parts, steps and interrelationships,
which are exemplified in the present disclosure, the scope of which
will be indicated in the appended claims.
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Brief Description of the Drawings
For a fuller understanding of the nature and scope of the
present invention, reference is made to the following detailed
specification, which is to be taken in connection with the
accompanying drawings wherein:
Fig. 1 is a perspective view of a product embodying the
present invention;
Fig. 2 is a perspective, exploded view of the components
of the product of Fig. l;
Fig. 3 is a flow illustration, exaggerated for emphasis,
of the steps of a process of the present invention;
Fig. 4 is a side view of another product embodying the
present invention;
Fig. 5 is an exaggerated perspective view, illustrating
certain features of the present invention; and
Fig. 6 is a flow illustration, exaggerated for emphasis,
of the steps of another process of the present invention.
Detailed Description of
the Embodiment of Figs. 1, 2 and 3
One embodiment of the present invention, as shown in Figs.
1 and 2, comprises an inner bearing assemblage 20 and an outer
bearing assemblage 22, between which a specimen is tested in
accordance with the present invention; a support assemblage 24 for
carrying inner bearing assemblage 20; and a bias assemblage 26 for
causing or not causing relative motion between the inner and outer
bearing assemblages during testing of a fluid therebetween.
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As shown, inner bearing assemblage 20 includes an inner
bearing ring 28 having an outer cylindrical bearing surface, which
is porous in accordance with the present invention. Bearing ring 28
has an inner cylindrical surface with a keyway. Bearing assemblage
22 also includes a cylindrical mount 30 that has an outer cylindrical
surface with a key. Ring 28 and mount 30 snugly mate with each other
so that they can be fitted together manually, retained in mated
condition frictionally, or separated from each other manually as
desired.
As shown, outer bearing assemblage 22 includes an outer
bearing ring 32 having an inner bearing surface which is porous in
accordance with the present invention. Bearing ring 32 has an outer
cylindrical surface with a keyway. Bearing assemblage 22 also
includes an annular mount 34 that has an inner cylindrical surface
with a key. Ring 32 and mount 34 mate with each other so that they
can be fitted together manually, retained in mated condition
frictionally, or separated from each other manually as desired.
Bearing mount 34 has a port 36 extending from its outer to its inner
surface and bearing ring 32 has a port 38 extending from its outer
to its inner surface. When bearing mount 34 and bearing ring 32 are
mated, ports 36 and 38 are aligned and constitute an orifice through
which a metered sample of fluid can be introduced by a syringe or the
like into the shear region between the inner and outer bearing
surfaces. Support assemblage 24 is in the form of horizontal rod 40
that, as shown, is adapted to be manually held. The outer diameter
of rod 40 and the outer diameter of bearing ring 28 are the same so
as to establish a continuous cylindrical surface. On rod 40 is a
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marker 42, which indicates the desired axial location of outer
bearing assemblage 22 on inner bearing assemblage 20. Bias asse~blage
26 includes a threaded shaft 44 that extends radially from annular
bearing mount 22 and a threaded nut 46 that is turned onto shaft 44
to an adjusted position at which selected bias is achieved.
In accordance with the present invention, at least one and
preferably both of the bearing surfaces of ring 28 and ring 32 are
predeterminedly porous, being characterized by sufficient capillarity
to absorb water and other aqueous, substantially Newtonian free-
flowing fluids. Preferably the axial length of outer ring 32 issufficiently short, i.e. between 0.3 and 5 centimeters, and the
radial distance between the inner and outer bearing surfaces is
sufficiently small, i.e. between 0.0001 and 0.050 millimeters, so
that a small sample of the fluid, i.e. 1 to 1000 microliters, will
fill the shear region. Preferably, each of the two bearing surfaces
should have an area of at least 250 millimeters so as to ensure that
the absorptive capacity of the surfaces will not be saturated. .
Preferably the pore diameter should average in the range from 0.1 to
500 microns and the depth of the porous layer underlying the porous
surface should be in excess of 1 micron, ranging normally up to 200
microns. Preferably the outside diameter of inner ring 28 ranges
from 0.3 to 2.0 centimeters. In various forms, the porous bearing
surfaces are provided by fired ceramic materials, etched vitrious
materials (particularly glasses), sintered powder m~tallurgical
composites, and etched metals and alloys. A particularly satisfactory
material is produced by etching the copper out of aluminum bronze by
an acid, particularly sulphuric acid.
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Operation of the Embodiment of Figs. 1, 2 and 3
The following non-limiting examples further illustrate the
present invention. In each of these examples the axial length of
outer ring 32 is approximately 2 centimeters, the radial distance
between the inner and outer bearing surfaces is approximately 0.01
millimeter, the bearing surfaces each has areas of approximately 500
millimeters, the average pore diameter is approximately 100 microns,
the depth Gf each of the porous layers is approximately 100 microns.
The process of the present invention contemplates indicating visco-
elastic changes in biological fluids resulting from pathologicalconditions, drug usage, the menstrual cycle, etc.
EXAMPLE I
In the case of obstructive pulmonary diseases such as
bronchitis, cystic fibrosis and emphysema, thick viscous discharges
are expectorated. The obstructive fractions are intermixed with
saliva, pulmonary surfactants, bacteria, water, electroytes and other
components. There are no "pure samples" and no two consecutive
specimens are alike since they may originate from the bronchi or
alveoli in different locations in the lungs involving regions that
may be more or less seriously involved. Certain drugs known as
mucolytic agents are used to liquify the tenacious viscous fractions
although their efficacy is difficult to measure. In accordance with
the present invention, testing a sample of such an expectorated
discharge involves inserting it into the shear region between the two
porous bearing surfaces of the test instrument, absorbing the more
fluid components into the bearing surfaces and biasing the bearing
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surfaces for relative movement in order to determine the lubricity
of the residue.
EXAMPLE II
The present invention is useful in determining the phase of
the menstrual cycle and, particularly, to indicating the rheological
properties of bodily mucus, particularly cervical mucus and/or oral
mucus, in order to predict the inception and to indicate the presence
of ovulation. The present invention thus is concerned with
conception control. It has been found that mucus samples from the
vaginal and oral cavities undergo distinct in-phase rheological
changes during the menstrual cycle. Although the changes in the
cervical mucus are much more noticeable than the changes in the oral
mucus, both changes are readily determinable. During the immediate
preovulatory phase, for a period of one to three days under estrogen
domination, the mucus is profuse and watery. During the post-
ovulatory phase, under progestation, the mucus becomes less abundant
and more viscous. In healthy women with normal menstrual cycles, as
is well documented in the medical literature, ovulation usuallyoccurs
between the 12th and 14th day prior to the next menstrual period
(and not after the preceding period). Specifically, cervical mucus
is most hydrated at the time of ovulation, containing 97 to 98%water,
and is relatively dehydrated at other times, containing only 80 to 90%
water. The solid residue after desiccation may range from 2% during
ovulation to 20% at other times, a ten fold increase. In accordance
with the present invention, testing a sample of cervical mucus
involves inserting it into the shear region between the two porous
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bearin~ surfaces of the test instrument, absorbing the watery fluid
components into the bearing surfaces and biasing the bearing surfaces
for relative motion in order to determine the lubricity of the
residue.
In each of the foregoing examples, testing of the residue
involved establishing a predetermined torque, which either causes
rotation of the outer bearing member or does not cause rotation of
the outer bearing member~as an indication of lubricity.
Detailed Description of the
Embodiment of Figs. 4, 5 and 6
Referring now to the drawings, particularly Figs. 4, 5 and
6, there is shown one embodiment of the invention in the form of a
device 60 comprising a pair of separable cooperating members 62 and
64 having working faces 66 and 68, respectively. Members 62 and 64
are composed of a dimensionally stable material, for example a
vitreous material such as glass, a plastic such as methylmethacrylate,
or a metallic material such as stainless steel. Each working face
defines a bearing surface of predetermined surface characteristics
having troughs and ridges of-triangular or other cross section, the
average valley to peak height being in the range of 0.001 to 5.0 mm.
Such a surface, in various embodiments, is characterized by a
predetermined depth and is provided by precision casting, machining,
hot pressing or etching regularly spaced troughs and ridges, the
outermost area of the ridges being non-pla~ar, i.e. being sharp or
rounded. In cross section, these spaced valleys and peaks take the
form of elongated increments which extend outwardly to ridge lines.
In the illustrated embodiment, by way of example, the predetermined
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surface of bearing surface 6, which is disposed at the lower face of
member 12, is in the form of a plurality elongated members 70 that
are in spaced parallel relationship with one another, each elongated
member 70 having a triangular cross-section profile occurring at a
rate of 5 to 5000 cycles per cm. In the illustrated embodiment, by
way of example, the predetermined surface of bearing surface 68,
which is disposed at the upper face of member 64, is in the form of
a plurality of elongated members 72 that are in spaced parallel
relationship with one another, each elongated member 72 having a
triangular cross-sectional profile occurring at a rate of 5 to 5000
cycles per cm.
In accordance with ~he present invention, each of surfaces
66 and 68 are predeterminedly porous, being characterized by
sufficient capillarity to absorb water and other aqueous, s~bstantially
Netwonian free-flowing fluids. Preferably the pore diameter should
average in the range from 0.1 to 500 microns on the depth of the
porous layer underlying the porous surface should be excess of 1
micron ranging normally up to 200 microns. In various forms, the
porous bearing surfaces are provided by fired ceramic materials,
etched vitreous materials (particularly glasses), sintered powder
metallurgical composites, and etched metals and alloys. A particularly
-satisfactory material is produced by etching the copper out of
- aluminum bronze by an acid, particularly sulfuric acid.
Member 62, which in the illustrated embodiment has a
circular (or square or rectangular) profile having a diameter in the
range of 0.5 to 4.0 cm, is formed with an axial opening 74 at an upper
face 76. One end of a rod 78 is pressed or threaded into opening 74,
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rod 78 projecting outwardly from and in perpendicular relationship
with face 76. One end of a resilient element 80, for example a
spring, is secured to the free end of rod 78. The other end of
spring 80 is fastened to a rod 82, which is coaxial with rod 78.
Rods 78 and 82 are composed of a suitable plastic such as methyl
methacrylate or polycarbonate. Element 62, 64 are constrained for
reciprocal motion toward and away from each other by a pair of slide
bearings 75, 77, which receive rod 78 and a rod 79 extending from
- member 64 in the manner that rod 78 extends from member 62. In
operation, elements 62, 64 initially are biased toward each other by
springs 81, 81 with a fluid sample at the interface. Rod 79 is
connected by a tension line 83 to a memory torque meter 85. Rod 87
is connected by a tension line 83 to a memory torque meter 85. Rod
82 is connected by a tension line 87 to a synchronous motor 89 having
the characteristics of constant torque at constant or variable speed.
The bias applied typically ranges from 0.1 to 1000 grams and is
related to the size and configuration of members 62 and 64. The
profile of member 64 conforms substantially to the profile of member
62.
Operation of the Embodiment of Figs. 4, 5 and 6
One process of the present invention, hereinafter described,
involves the use of device 60 for determining the properties of a
fluid. First, a sample of fluid is obtained by inserting member 62
into the fluid or by placing a sample between the surfaces. Next,
member 62 is removed from the fluid, a sample of fluid being contained
on bearing surface 66. Next, immediately after removal of member 62,
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bearing surface 66 is placed on and pressed against bearing surface
68, whereby the fluid is spread on the bearing surfaces. Bearing
surface 66 is placed on bearing surface 68 in such a manner that the
longitudinal axis of each elongated member 70 is disposed in
substantially perpendicular relationship with respect to the
longitudinal axis of each elongated member 72. When members 62 and
64 are pressed together, a plurality of fluid containing regions 86
are formed therebetween. The surface area of each fluid containing
regions is substantially greater than the surface area of the
interface between the bearing surfaces, the surfaces of region 86
being denoted by reference character 88 and the interface being
denoted by reference character 90. When the bearing surfaces are
pressed together, the fluid sample is spread to the boundary surfaces
of regions 86 and excess flows out of the extremities of the troughs,
the bearing surfaces being operative to provide an even thickness of
the spread fluid. Next, synchronous motor 89 pulls upwardIy on
tension line 87 or in a direction that is substantially perpendicular
to the plane of the interface between members 62 and 64. The more
viscous the fluid, the greater the force necessary to pull the
elements apart. Spring 80 is operative to prevent shock loading
during mating of the members 62 and 64 and during separation of the
members.
It is to be understood that the present invention contemplates
a variety of control techniques by which precise measurements of
rheological properties can be obtained. It is to be understood that
the present invention contemplates the use of eccentrically positioned
circuiar bearing surfaces as well as the concentric bearing surfaces
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specifically disclosed herein. Since certain changes may be made in
the present disclosure without departing from the scope hereof, it
is intended that all matter contained in the above specification or
shown in the accompanying drawings be interpreted in an illustrative
and not in a limiting sense.
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