U.S. patent application number 17/144570 was filed with the patent office on 2021-07-15 for blood pump with improved leakage control.
The applicant listed for this patent is ABIOMED, Inc.. Invention is credited to Soumen Das, Qingchao Kong, Alexander Ship, Zhenghong Tao.
Application Number | 20210213274 17/144570 |
Document ID | / |
Family ID | 1000005372083 |
Filed Date | 2021-07-15 |
United States Patent
Application |
20210213274 |
Kind Code |
A1 |
Das; Soumen ; et
al. |
July 15, 2021 |
BLOOD PUMP WITH IMPROVED LEAKAGE CONTROL
Abstract
A blood pump with a stator and rotor wherein the rotor is
assembled by bonding the stator components with epoxy. The bonding
surfaces of the rotor components are primed with a silane-based
primer to improve adhesion between the primer and the rotor
components by rendering such surfaces hydrophobic. A bonding
surface of one of the stator yoke or the stator sleeve, or both, is
treated with a primer that improves wettability of the bonding
surface and improves bonding of the epoxy to the binding surface.
The device has a bonding surface adhered to epoxy in which a primer
was applied on such bonding surface prior to introducing epoxy onto
the bonding surface. In addition to improved bond strength,
hydrophobic surface would control moister ingress.
Inventors: |
Das; Soumen; (Danvers,
MA) ; Kong; Qingchao; (Danvers, MA) ; Tao;
Zhenghong; (Danvers, MA) ; Ship; Alexander;
(Danvers, MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ABIOMED, Inc. |
Danvers |
MA |
US |
|
|
Family ID: |
1000005372083 |
Appl. No.: |
17/144570 |
Filed: |
January 8, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62959552 |
Jan 10, 2020 |
|
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|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61M 2207/00 20130101;
A61M 60/135 20210101; F04D 13/06 20130101; A61M 60/829 20210101;
A61M 60/411 20210101; F04D 9/00 20130101; A61M 60/806 20210101 |
International
Class: |
A61M 60/411 20060101
A61M060/411; A61M 60/135 20060101 A61M060/135; A61M 60/806 20060101
A61M060/806; A61M 60/829 20060101 A61M060/829; F04D 13/06 20060101
F04D013/06; F04D 9/00 20060101 F04D009/00 |
Claims
1. A blood pump, comprising: a pump motor comprising a rotor
portion having proximal and distal ends and a stator portion having
proximal and distal ends, wherein the proximal portion of the rotor
portion is received into a cavity defined by the stator portion;
the rotor portion comprising an impeller, wherein the impeller
comprises impeller blades and a drive unit, the impeller blades
positioned at the distal end of the rotor portion and not received
into the stator and the drive unit positioned in a portion of the
rotor received into the stator portion, wherein the drive unit is
coupled to the impeller blades; the stator portion comprising a
yoke, a coil and a coil holding sleeve, the sleeve defining the
cavity into which the proximal portion of the rotor is received;
wherein the yoke, coil and sleeve have interior and exterior
surfaces, wherein epoxy is introduced between the yoke and the coil
and the coil and the sleeve, thereby substantially embedding the
coil in epoxy, wherein at least one of the interior surface of the
yoke, the exterior surface of the coil, the interior surface of the
coil or the exterior surface of the sleeve are treated with a
primer prior to the introduction of epoxy therebetween.
2. The blood pump of claim 1 wherein the primer is a silane
solution.
3. The blood pump of claim 2 wherein the silane has the general
chemical formula (RO).sub.3SiCH.sub.2CH.sub.2CH.sub.2--X wherein RO
is a hydrolysable group.
4. The blood pump of claim 3 wherein the hydrolysable group is
selected from the group consisting of methoxy, ethoxy, or
acetoxy.
5. The blood pump of claim 4 wherein X is an organofunctional
group.
6. The blood pump of claim 1 wherein the interior surface of the
yoke is treated with the primer wherein the primer is a silane
solution such that the silane is interposed between the interior
surface of the yoke and the epoxy.
7. The blood pump of claim 1 wherein exterior surface of the coil
is treated with the primer wherein the primer is a silane solution
such that the silane is interposed between the exterior surface of
the coil and the epoxy.
8. The blood pump of claim 1 wherein the interior surface of the
coil is treated with the primer wherein the primer is a silane
solution such that the silane is interposed between the interior
surface of the coil and the epoxy.
9. The blood pump of claim 1 wherein the exterior surface of the
sleeve is treated with the primer wherein the primer is a silane
solution such that the silane is interposed between the exterior
surface of the sleeve and the epoxy.
10. A method for making a blood pump the method comprising:
assembling a pump motor comprising a rotor portion having proximal
and distal ends and a stator portion having proximal and distal
ends, wherein the proximal portion of the rotor portion is received
into a cavity defined by the stator portion; the rotor portion
comprising an impeller, wherein the impeller comprises impeller
blades and a drive unit, the impeller blades positioned at the
distal end of the rotor portion and not received into the stator
and the drive unit positioned in a portion of the rotor received
into the stator portion, wherein the drive unit is coupled to the
impeller blades; the stator portion comprising a yoke, a coil and a
coil holding sleeve, the sleeve defining the cavity into which the
proximal portion of the rotor is received; wherein the yoke, coil
and sleeve have interior and exterior surfaces; treating at least
one of the interior surface of the yoke, the exterior surface of
the coil, the interior surface of the coil or the exterior surface
of the sleeve with a primer; and introducing epoxy between the yoke
and the coil and the coil and the sleeve, thereby substantially
embedding the coil in epoxy.
11. The method of claim 1 wherein the primer is a silane
solution.
12. The method of claim 11 wherein the silane has the general
chemical formula (RO).sub.3SiCH.sub.2CH.sub.2CH.sub.2--X wherein RO
is a hydrolysable group.
13. The method of claim 12 wherein the hydrolysable group is
selected from the group consisting of methoxy, ethoxy, or
acetoxy.
14. The method of claim 13 wherein X is an organofunctional
group.
15. The method of claim 10 wherein the interior surface of the yoke
is treated with the primer wherein the primer is a silane solution
such that the silane is coated on the interior surface of the yoke
when the epoxy is introduced between the yoke and the coil.
16. The method of claim 10 wherein exterior surface of the coil is
treated with the primer wherein the primer is a silane solution
such that the silane is coated on the exterior surface of the coil
when the epoxy is introduced between the yoke and the coil.
17. The method of claim 10 wherein the interior surface of the coil
is treated with the primer wherein the primer is a silane solution
such that the silane is coated on the interior surface of the coil
when the epoxy is introduced between the coil and the sleeve.
18. The blood pump of claim 10 wherein the exterior surface of the
sleeve is treated with the primer wherein the primer is a silane
solution such that the silane is coated on the exterior surface of
the sleeve when the epoxy is introduced between the coil and the
sleeve.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] The present application claims priority to U.S. Provisional
Application No. 62/959,552 filed Jan. 10, 2020, the disclosure of
which is incorporated by reference in its entirety.
TECHNICAL FIELD
[0002] This invention relates to a blood pump, in particular an
intravascular blood pump, to support a blood flow in a patient's
blood vessel.
BACKGROUND
[0003] Blood pumps of different types are known, such as axial
blood pumps, centrifugal blood pumps, or mixed-type blood pumps,
where the blood flow is caused by both axial and radial forces.
Intravascular blood pumps are inserted into a patient's vessel such
as the aorta by means of a catheter. A blood pump typically
comprises a pump casing having a blood flow inlet and a blood flow
outlet. In order to cause a blood flow from the blood flow inlet to
the blood flow outlet, an impeller or rotor is rotatably supported
with the pump casing about an axis of rotation, with the impeller
being provided with on or more impeller blades for conveying blood.
A blood pump is described in US Patent Publication No. 2018/0228953
to Seiss et al., which is incorporated by reference herein. Pumps
are also described in U.S. Pat. No. 5,911,685 entitled "Method and
Apparatus for Cardiac Blood Flow Assistance" to Seiss et al., U.S.
Pat. No. 6,794,789 entitled "Miniature Motor" to Seiss et al., U.S.
Pat. No. 9,402,942 to Hastle et al. entitled "Loading Guide Lumen"
and U.S. Pat. No. 9,872,948 to Siess, all of which are incorporated
by reference herein.
[0004] The motor 100 of a blood pump is illustrated in FIG. 1. The
impeller has a drive unit 111 and impeller blades 110 are on the
distal end 126 of the motor 100. The motor 100 has a stator 120 and
a rotor 130. The skilled person is aware that rotary systems
typically have a stator (the stationary portion) and a rotor (the
rotating portion). FIG. 2 illustrates the motor of FIG. 1 in an
exploded view with the rotor 130 outside the stator 120.
[0005] FIG. 3 is an exploded view of the stator. The stator has a
yoke 121, a coil 122, and a coil holding sleeve 123. The yoke 121
is typically made of metal, while the coil 122 is typically made of
copper. The coil holding sleeve 123 can be either plastic or
ceramic. These components are illustrated in an exploded view in
FIG. 3. The coil holding sleeve 123 in FIG. 3 is made of
ceramic.
[0006] FIG. 4 is a cross section of the stator of FIG. 2 and also
illustrates the yoke 121, the coil 122 and the coil holding sleeve
123. The stator is assembled using epoxy adhesive 124 to provide a
stable and secure assembly. The epoxy 124 essentially encapsulates
the coil 122 such that epoxy 124 is at the yoke 121/coil 122
interface and the coil 122/sleeve 123 interface. FIG. 5 is a stator
120 cross section that illustrates the windings that form the coils
123. The stator has epoxy 124 interposed between the metal yoke 121
and the coil 122 and between the coil 122 and the sleeve 123. The
sleeve 123 illustrated in FIG. 5 is a plastic sleeve.
[0007] One skilled in the art is aware that a variety of epoxy
adhesives are suitable for use in a blood pump. US Patent
Publication No. 20180280598, which is entitled Thermistor Imbedded
[sic] Therapeutic Catheter, describes an intracardiac blood pump
that includes an electrically driven motor, a rotor positioned
within the blood pump (for example in the cannula), and an
electrical line configured to supply current to the motor. In some
embodiments the motor is implanted with the rotor. Optionally, the
pump is described as powered by an external motor with a drive
cable that extends through the catheter and out to a drive unit
located external to the patient. US Patent Publication No.
20180280598 is incorporated by reference herein. US Patent
Publication describes a blood pump that has a thermistor with a
temperature sensitive head. The temperature sensitive head is
described as being embedded in epoxy. U.S. Pat. No. 5,089,016
describes an implantable blood pump with a toroidal chamber coated
with epoxy (e.g. Stycast Epoxy 1267).
[0008] Reliable and consistent blood pump operation is critical to
patient care. Therefore, due to the environment in which the pumps
are configured to operate, the performance of certain pump
components can degrade over time. Therefore, modifications to blood
pumps that mitigate such problems continue to be sought.
BRIEF SUMMARY
[0009] Described herein is a pump motor for a blood pump and a
method for making the pump motor. The pump motor has a rotor
portion having proximal and distal ends and a stator portion having
proximal and distal ends, wherein the proximal portion of the rotor
portion is received into a cavity defined by the stator portion at
the distal end of the stator portion. The rotor portion has an
impeller, wherein the impeller comprises impeller blades and a
drive unit. The impeller blades are positioned at the distal end of
the rotor portion and not received into the stator. The drive unit
is positioned in a portion of the rotor received into the stator
portion. The drive unit is coupled to the impeller blades. The
stator portion has a yoke, a coil and a coil holding sleeve. The
sleeve defines the cavity into which the proximal portion of the
rotor is received.
[0010] The yoke, coil and sleeve have interior and exterior
surfaces, wherein epoxy is introduced between the yoke and the coil
and the coil and the sleeve, thereby substantially embedding the
coil in epoxy, wherein at least one of the interior surface of the
yoke, the exterior surface of the coil, the interior surface of the
coil or the exterior surface of the sleeve are treated with a
primer prior to the introduction of epoxy therebetween.
[0011] The pump motor is made by assembling a pump motor from a
rotor portion with proximal and distal ends and a stator portion
having proximal and distal ends. The proximal portion of the rotor
portion is received into a cavity defined by the stator portion.
The rotor portion has an impeller, wherein the impeller has
impeller blades and a drive unit. The impeller blades are
positioned at the distal end of the rotor portion and are not
received into the stator. The drive unit is positioned in a portion
of the rotor received into the stator portion. The drive unit is
coupled to the impeller blades. The stator portion has a yoke, a
coil and a coil holding sleeve, the sleeve defining the cavity into
which the proximal portion of the rotor is received.
[0012] The yoke, coil and sleeve have interior and exterior
surfaces. According to the method, least one of the interior
surface of the yoke, the exterior surface of the coil, the interior
surface of the coil or the exterior surface of the sleeve are
treated with a primer. After the one or more surfaces are treated,
epoxy is introduced between the yoke and the coil and the coil and
the sleeve, thereby substantially embedding the coil in epoxy.
BRIEF DESCRIPTION OF DRAWINGS
[0013] FIG. 1 illustrates a blood pump motor having a stator and a
rotor;
[0014] FIG. 2 illustrates an exploded view of the blood pump motor
of FIG. 1;
[0015] FIG. 3 is an exploded view of the stator of FIG. 2;
[0016] FIG. 4 is a cross section of the stator of FIG. 2 along line
A-A;
[0017] FIG. 5 is another view of the stator cross-section of FIG.
4;
[0018] FIGS. 6A-B illustrate the effect of moisture ingress in a
blood pump rotor (FIG. 6A) and stator (FIG. 6B);
[0019] FIG. 7 illustrates a blood pump motor according to one
embodiment of the present invention;
[0020] FIG. 8A-B illustrates the stator with coated surfaces;
[0021] FIG. 9 illustrates a yoke with an interior surface that is
surface treated;
[0022] FIG. 10 illustrates a coil with an exterior surface that is
surface treated;
[0023] FIG. 11 illustrates a sleeve with an exterior surface that
is surface treated
[0024] FIG. 12 is an image of a stator with a portion of the yoke
removed to reveal moisture ingress evidence into the epoxy
underlying the yoke;
[0025] FIG. 13A illustrates a stator tear down with good adhesion
between the yoke and the epoxy;
[0026] FIG. 13 B illustrates a stator tear down with poor adhesion
between the yoke and the epoxy;
[0027] FIG. 14 illustrates the effect of primer on surface
wettability; and
[0028] FIG. 15 illustrates primer effectiveness for reducing
leakage current.
DETAILED DESCRIPTION
[0029] Blood pumps are deployed in patients that require critical
and life-saving care. Consequently, it is important to remediate
any aspect of the device that might adversely affect pump
operation. Leakage Current (LC) is one such failure mode.
[0030] One cause of leakage current is the moisture ingress into
the pump stator/rotor assembly. Moisture ingress can occur at the
interface between the epoxy and sleeve (such moisture ingress
illustrated in FIG. 6A) and between the epoxy and the yoke (such
moisture ingress illustrated in FIG. 6B). As noted above, the
stator of such blood pumps have a coil 122 that is essentially
embedded in epoxy. The epoxy encapsulates the coil and fills the
cavity to form the stator body.
[0031] Suitable epoxies for assembling the stator described herein
are well known to those skilled in the art and not described in
detail herein. Examples of suitable epoxies are an amine base
two-part epoxy such as Delo-Duopox, which is obtained from DELO
Industrial Adhesives and EPO-TEK.RTM. 301 from Epoxy Technology,
Inc. of Billerica, Mass. Suitable epoxies for use in blood pumps
are well known to those skilled in the art and are not described in
detail herein.
[0032] FIG. 6A illustrates moisture ingression evidence on a coil
122, the moisture ingression from the distal end 126 (FIG. 2) of
the stator 120. The moisture is indicated by the shaded areas 125.
FIG. 6B illustrates evidence of moisture ingression 125 on the
epoxy 124 adjacent the yoke 121, a portion of which is removed to
reveal that the epoxy had not adhered well thereto.
[0033] Therefore, due to the environment in which the pumps are
configured to operate, the performance of certain pump components
can degrade over time. Pumps that mitigate such problems are
described herein. The method and device described herein increases
the bonding strength between the yoke and the epoxy by improving
the wettability of the substrate surface (i.e. the surface to which
the epoxy is intended to adhere) by the uncured epoxy. The
increased bonding strength prevents moisture ingress. Moisture
ingress indicates poor adhesion between the sleeve (either ceramic
or plastic) and the epoxy. Bonding to ceramic sleeves (e.g. alumina
toughened zirconia (ATZ)) in particular is difficult due to the
topology of ceramic surfaces.
[0034] In the assembly of the blood pump, the epoxy is applied in
multiple locations. The epoxy encapsulates the coils to isolate and
insulate the coils from the components adjacent to the coils that
could otherwise contact the coils. The epoxy also fills the
spaces/voids between the sleeve, the coil and the yoke, thereby
providing structural strength to the assembled blood pump and
avoiding/preventing/mitigating micromovement of the assembled blood
that might otherwise occur as the external environment of the pump
changes. The epoxy also facilitates the heat transfer from the
coils to outside the pump.
[0035] However, the gaps between the sleeve, coils and the yoke
into which the epoxy is introduced are very small. Such gaps are
typically about one micron. As a result, it is important to have a
reliably good and consistent surface wettability of the pump
component (e.g. coil, sleeve, yoke, etc.) to the uncured epoxy.
When the epoxy is injected into the cavities or gaps, a higher
wettability surface causes the epoxy to spread evenly and
completely fill the small gaps between the pump components. The
improved surface wettability for the uncured epoxy results in a
higher bonding strength of the epoxy to the adjacent component and
excellent encapsulation of components such as the coil. On the
contrary, if the substrate (i.e. the component surface) wettability
is low or the surface is not otherwise compatible with the uncured
epoxy, the uncured epoxy flows away from the substrate surface. As
a result of low or poor surface wettability, a low bonding strength
between the epoxy and the substrate, or gaps between the substrate
and the epoxy, or both, will occur.
[0036] The low bonding strength or the gaps between the epoxy and
the substrate allow paths to form at the interface between the
cured epoxy and the surface of the adjacent pump component through
which moisture can travel. Also, gaps function as a heat insulator,
which adversely affects the efficiency of heat transfer from the
coils to the pump exterior. As a result, the amount of heat
dissipated from the coil can be dramatically reduced.
[0037] Disclosed herein is an apparatus and method that describes a
simple substrate surface treatment that will improve
surface-wettability of the substrate to which the epoxy will
adhere, improving both the bonding strength of the epoxy to the
substrate and the extent of the bonding between the epoxy and the
substrate surface. Referring to FIG. 14, the wettability of a
primer-treated ceramic surface 210 (i.e. the sleeve) and a
non-treated ceramic surface 200 is illustrated. Referring to
surface 200, the isolated shaded regions 201 (i.e., the beaded
regions) indicate that the fluid 201 applied to the substrate
surface 200 was not compatible with the substrate surface 200.
Consequently, the fluid 201 forms on the surface 200 as liquid
beads leaving a substantial area of the substrate surface 200
uncovered by the liquid. On the other end, the surface 210 is more
substantially covered by the liquid 211, indicating that surface
210 is more compatible with the liquid. The liquid 211 is more
uniformly spread around the surface 211 and, as a consequence of
the increased substrate surface wetting, there will be increased
bonding strength between the substrate surface and the cured epoxy.
FIG. 14 illustrates that the primer-treated surface described
herein enhances the quality of the bond between the epoxy and the
substrate.
[0038] The primers described herein not only improve wettability of
the substrate to the uncured epoxy, but also modify the substrate
surfaces that are otherwise hydrophilic and make those surfaces
hydrophobic. The resulting hydrophobic surfaces resist moisture
ingress into any remaining gaps between the epoxy and the
substrate.
[0039] The method and device described herein deploys a primer onto
the epoxy (or the surface to which the epoxy will adhere). The
primer improves adhesion of the bonding surface to the epoxy. The
positive effect of applying primer to enhance the adhesion to a
substrate material is illustrated in FIG. 13A. FIG. 13A illustrates
a stator 120 in which a portion of the yoke 121 is separated from
the stator 120. The stator 120 in FIG. 13A had epoxy 124 treated
with a silane solution. Silane solutions are known primers that
function at the interface between the uncured epoxy and act as an
adhesion promoter. The silane primer is chosen by matching its
organic functionality to the polymer to optimize bonding. The
selection of a silane primer that will render the substrate surface
hydrophobic and enhance surface wettability/bonding with the epoxy
is described in A Guide to Silane Solutions .COPYRGT.2009 Dow
Corning Corporation, which is incorporated by reference herein.
Silane coupling agents contain two types of reactivity, inorganic
and organic, in the same molecule. Silane have the general chemical
formula (RO).sub.3SiCH.sub.2CH.sub.2CH.sub.2--X wherein RO is a
hydrolysable group such as methoxy, ethoxy, or acetoxy and X in an
organofunctional group such as amino, methacryloxy, epoxy, etc. One
skilled in the art can select a suitable silane primer for use with
the present invention. The alkoxy groups hydrolyze and the
resulting hydroxyl groups bond to the hydroxyl groups on the
inorganic substrate surfaces (e.g., the metal, metal oxide and
ceramic surfaces described herein. The epoxy adheres strongly to
the primed surface of the yoke 121 such that the epoxy and even a
portion of the coil 122 is torn away with the portion of the yoke
121 separated from the stator 120. The surface treatment is
performed prior to the stator being injection molded. Basically,
here is a brief flow: 1). the coil is attached to the sleeve; 2).
wires and cables are soldered to a printed circuit board (PCB)
which is then adhered to the ceramic sleeve; 3). the yoke inner
diameter (ID) is treated with primer (FIG. 9); 4). the sleeve/coil
outer diameter (OD) is then treated with primer (FIGS. 10 and 11);
5). the yoke is installed over the sleeve/coil subassembly; and 6).
epoxy is injected into the assembly.
[0040] The stator 120 in FIGS. 12 and 13B did not have primer
applied to the interior surface of the yoke 121. This is apparent
since the portion of the yoke 121 that is separated from the stator
120 has no epoxy 124 thereon. This illustrates that there was
little to no bonding of the epoxy 124 to the yoke 121 in the stator
120 illustrated in FIG. 13B. FIG. 6B also illustrates a stator 120
in which the epoxy 124 did not adhere to the portion of the yoke
121 removed from the stator. As stated above, the shaded epoxy
region 124 indicates moisture ingress, demonstrating that, due to
the poor adhesion between the epoxy 124 and the yoke 121, moisture
was able to migrate into the interface between the yoke 121 and the
epoxy 124. Contrast the stator in FIG. 13B with that in FIG. 13A,
where the bonding surface was treated as described herein. The yoke
121 was significantly damaged when a portion of the yoke 121 was
separated from the stator 120.
[0041] The primer also improves the bond between the sleeve 123 and
the epoxy 124. Just as the epoxy 124 remains adhered to the portion
of the yoke 121 separated from the stator 120, at least a portion
of the epoxy will remain adhered to the sleeve 123 during a tear
down process in which the sleeve (or a portion thereof) is
separated from the stator 120.
[0042] Described herein is a motor for a blood pump in which one or
more operating surfaces of the blood pump stator are surface
treated to mitigate the problems with moisture that can lead to an
increase in leakage current of the motor. FIG. 7A highlights the
interface 129 between the yoke 121 and the coil/sleeve 122/123.
Referring to FIG. 8A, the stator 120 has a silane treated surface
on the interior of the yoke 121, the exterior of the coil 122 and
exterior of the sleeve 123. The silane treated surface is 128 in
FIG. 8B. In the cross section of FIG. 8B the coil is not visible
because it is embedded in the epoxy 124.
[0043] In one embodiment a silane primer is provided to improve the
bonding between the epoxy and the yoke and or the sleeve.
Application of silane primer eliminated the leakage current by
improving the adhesion between ceramic sleeve and the epoxy (e.g.,
EPO-TEK.RTM. 301 (ES2019-181 rA).
[0044] FIG. 15 illustrates that pumps in which the primer was
applied to the surface of at least some of the pump components
prior to the introduction of epoxy had consistently lower leakage
current. Pumps that were assembled without the application of the
primer prior to epoxy injection had a range of leakage current
results. Therefore, the application of the primer to the surface of
the pump components provides the assembled pumps with reliable and
acceptable performance regarding leakage current.
[0045] As noted above, wetting of the bonding surfaces as well as
chemical bond formation with the bonding surface provides better
adhesion between two different surfaces (e.g., the epoxy and the
yoke surface or the sleeve surface.
[0046] As noted above, the primers described herein are
silane-based primers. Such primers improve the wetting of epoxies
such as EPOTEK.RTM. 301 on the surface of the ceramic sleeve or the
metal yoke for better adhesion. As noted above, the silane forms a
chemical bond with the substrate surface and with the epoxy that
improves the adhesion strength between the epoxy and the substrate
(e.g. the metal yoke/ceramic sleeve of the pump. Silane based
primers that act as coupling agent between the relevant pump
component and the adjacent epoxy that are both hydrophobic and
organophilic are contemplated as suitable herein.
[0047] In this specification, the word "comprising" is to be
understood in its "open" sense, that is, in the sense of
"including", and thus not limited to its "closed" sense, that is
the sense of "consisting only of". A corresponding meaning is to be
attributed to the corresponding words "comprise", "comprised" and
"comprises" where they appear.
[0048] While particular embodiments of this technology have been
described, it will be evident to those skilled in the art that the
present technology may be embodied in other specific forms without
departing from the essential characteristics thereof. The present
embodiments and examples are therefore to be considered in all
respects as illustrative and not restrictive. It will further be
understood that any reference herein to subject matter known in the
field does not, unless the contrary indication appears, constitute
an admission that such subject matter is commonly known by those
skilled in the art to which the present technology relates.
* * * * *