U.S. patent application number 12/887730 was filed with the patent office on 2011-11-03 for biocompatible and biostable implantable medical device.
This patent application is currently assigned to ALLERGAN, INC.. Invention is credited to Mike Augarten, Marcos Borrell, Kaustubh S. Chitre, Christopher R. Deuel, Babak Honaryar, Christian Y. Perron, Sean Snow, Erik Torjesen, Nikhil S. Trilokekar.
Application Number | 20110270022 12/887730 |
Document ID | / |
Family ID | 44858766 |
Filed Date | 2011-11-03 |
United States Patent
Application |
20110270022 |
Kind Code |
A1 |
Honaryar; Babak ; et
al. |
November 3, 2011 |
BIOCOMPATIBLE AND BIOSTABLE IMPLANTABLE MEDICAL DEVICE
Abstract
The present invention is related to a biocompatible and
biostable implantable medical device. The present invention can
include an implantable medical device including an
electro-mechanical component. The electro-mechanical component can
be coated with various novel and nonobvious coating combinations
designed to promote biocompatibility and biostability. One layer of
the coating combinations can be a tie layer. Another layer of the
coating combinations can be a layer formed on top of the tie layer,
and having biocompatible and biostable properties.
Inventors: |
Honaryar; Babak; (Orinda,
CA) ; Augarten; Mike; (Goleta, CA) ; Borrell;
Marcos; (Goleta, CA) ; Chitre; Kaustubh S.;
(Goleta, CA) ; Perron; Christian Y.; (Goleta,
CA) ; Snow; Sean; (Capinteria, CA) ; Torjesen;
Erik; (Goleta, CA) ; Trilokekar; Nikhil S.;
(Goleta, CA) ; Deuel; Christopher R.; (Arlington,
MA) |
Assignee: |
ALLERGAN, INC.
Irvine
CA
|
Family ID: |
44858766 |
Appl. No.: |
12/887730 |
Filed: |
September 22, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61330266 |
Apr 30, 2010 |
|
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Current U.S.
Class: |
600/37 ;
427/2.1 |
Current CPC
Class: |
A61F 5/0059 20130101;
A61M 2205/583 20130101; A61F 5/0013 20130101; A61M 39/0208
20130101; A61M 2205/215 20130101; A61M 2039/0238 20130101; A61M
2205/82 20130101; A61M 2210/1053 20130101; A61F 5/003 20130101;
A61F 5/0056 20130101; A61M 2039/0226 20130101; A61F 2/04
20130101 |
Class at
Publication: |
600/37 ;
427/2.1 |
International
Class: |
A61F 2/04 20060101
A61F002/04; B05D 5/00 20060101 B05D005/00 |
Claims
1. An access port for use in conjunction with a gastric band, the
access port comprising: a housing; and an electro-mechanical
component located within the housing, wherein the
electro-mechanical component is coated with a coating
combination.
2. The access port of claim 1, wherein the gastric band is a
hydraulically adjustable gastric band.
3. The access port of claim 1 further comprising: a penetrable
septum formed on the housing; and a conduit configured to carry
fluid between the penetrable septum and an inflatable portion of
the gastric band.
4. The access port of claim 3, wherein the electro-mechanical
component is a pressure sensor in communication with a fluid within
the gastric band and configured to monitor a parameter of the
fluid, generate a pressure value signal based on the parameter, and
communicate the pressure value signal to an external control unit
via RF telemetry.
5. The access port of claim 4, further comprising a plate element
positioned between the penetrable septum and the pressure sensor to
guard the pressure sensor against a needle damaging it.
6. The access port of claim 1, wherein the electro-mechanical
component is a printed circuit board assembly.
7. The access port of claim 1, wherein the electro-mechanical
component is a motor.
8. The access port of claim 1 wherein the coating combination
includes a tie layer.
9. The access port of claim 1, wherein the coating combination
comprises at least two different layers selected from the group
consisting of parylene, diamond like carbon, titanium nitride,
titanium carbide, silicon nitride, cyclo olefin copolymer, cyclo
olefin polymer, epoxy, silicone polymer, glass,
chloro-tri-fluoro-ethylene, poly-chloro-tri-fluoro-ethylene,
poly-ether-ether-ketone, polysulfone, polyoxymethylene,
polypropylene, liquid crystal polymer, ultra high molecular weight
polyethylene, fluoropolymer acrylate, and synthetic diamond.
10. The access port of claim 9, wherein the at least two different
layers are applied by one or more of chemical vapor deposition,
physical vapor deposition, plasma enhanced chemical vapor
deposition, injection molding, compression molding, transfer
molding, film forming, thermoforming, vacuum forming, or
dipping.
11. The access port of claim 1, wherein the coating combination is
biocompatible for at least 10 years.
12. The access port of claim 1 wherein the coating combination
includes a first layer having conformal and adhesive properties,
and a second layer on top of the first layer having biocompatible
and biostable properties.
13. An access port for a gastric band comprising: a penetrable
septum defining an outer wall of a housing; a conduit configured to
provide fluid communication between the penetrable septum and the
gastric band; a pressure sensor in fluid communication with a fluid
within the gastric band; and a printed circuit board assembly
connected to the pressure sensor, wherein the printed circuit board
assembly is coated with a coating combination.
14. The access port of claim 13, wherein the coating combination
comprises at least two different layers selected from the group
consisting of parylene, diamond like carbon, titanium nitride,
titanium carbide or silicon nitride, cyclo olefin copolymer, cyclo
olefin polymer, epoxy, silicone polymer, glass,
chloro-tri-fluoro-ethylene, poly-chloro-tri-fluoro-ethylene,
poly-ether-ether-ketone, polysulfone, polyoxymethylene,
polypropylene, liquid crystal polymer, ultra high molecular weight
polyethylene, fluoropolymer acrylate, and synthetic diamond.
15. The access port of claim 13 wherein the coating combination
includes a tie layer.
16. The access port of claim 15 wherein the coating combination
includes a layer formed on top of the tie layer, and which has
biocompatible and biostable properties.
17. The access port of claim 13 wherein the pressure sensor is
coated with the coating combination.
18. An access port for a gastric band comprising: a penetrable
septum defining an outer wall of a housing; a conduit configured to
provide fluid communication between the penetrable septum and the
gastric band; and a pressure sensor in fluid communication with a
fluid within the gastric band, wherein the pressure sensor is
coated with a coating combination.
19. The access port of claim 18, wherein the coating combination
comprises at least two different layers selected from the group
consisting of parylene, diamond like carbon, titanium nitride,
titanium carbide, silicon nitride, cyclo olefin copolymer, cyclo
olefin polymer, epoxy, silicone polymer, glass,
chloro-tri-fluoro-ethylene, poly-chloro-tri-fluoro-ethylene,
poly-ether-ether-ketone, polysulfone, polyoxymethylene,
polypropylene, liquid crystal polymer, ultra high molecular weight
polyethylene, fluoropolymer acrylate, and synthetic diamond.
20. The access port of claim 18 wherein the coating combination
includes a tie layer.
21. The access port of claim 20 wherein the coating combination
includes a layer formed on top of the tie layer, and which has
biocompatible and biostable properties.
22. An implantable medical device comprising: an electro-mechanical
component coated with a coating combination including a tie
layer.
23. The implantable medical device of claim 22, wherein the coating
combination comprises at least two different layers selected from
the group consisting of parylene, diamond like carbon, titanium
nitride, titanium carbide, silicon nitride, cyclo olefin copolymer,
cyclo olefin polymer, epoxy, silicone polymer, glass,
chloro-tri-fluoro-ethylene, poly-chloro-tri-fluoro-ethylene,
poly-ether-ether-ketone, polysulfone, polyoxymethylene,
polypropylene, liquid crystal polymer, ultra high molecular weight
polyethylene, fluoropolymer acrylate, and synthetic diamond.
24. The implantable medical device of claim 22 wherein the coating
combination includes a layer formed on top of the tie layer, and
which has biocompatible and biostable properties.
25. A method for protectively coating a long term medical device
comprising: coating the long term medical device with a tie layer;
and coating the long term medical device with a biostable and
biocompatible material.
26. The method of claim 25, wherein the biostable and biocompatible
material is selected from a group consisting of parylene, diamond
like carbon, titanium nitride, titanium carbide, silicon nitride,
cyclo olefin copolymer, cyclo olefin polymer, epoxy, silicone
polymer, glass, chloro-tri-fluoro-ethylene,
poly-chloro-tri-fluoro-ethylene, poly-ether-ether-ketone,
polysulfone, polyoxymethylene, polypropylene, liquid crystal
polymer, ultra high molecular weight polyethylene, fluoropolymer
acrylate, and synthetic diamond.
27. The method of claim 25 further comprising plasma treating the
long term medical device.
28. The method of claim 25 further comprising coating the long term
medical device in a clean room meeting the ISO class 6 ISO 14644-1
clean room standard.
Description
RELATED APPLICATIONS
[0001] This application claims priority to and the benefit of U.S.
Provisional Patent Application No. 61/330,266, entitled
"BIOCOMPATIBLE AND BIODURABLE, ELECTRONICALLY ENHANCED ACCESS PORT
FOR A FLUID FILLED IMPLANT" filed on Apr. 30, 2010, the entire
disclosure of which is incorporated herein by reference.
FIELD
[0002] The present invention broadly relates to medical devices and
more specifically, to a biocompatible and biostable implantable
medical device.
BACKGROUND
[0003] There are numerous varieties of implantable medical devices,
such as fluid filled surgical implants presently comprising, or
which may in the future comprise, access ports, for hydraulically
adjustable gastric bands.
[0004] An exemplary hydraulic adjustable gastric band comprises a
saline solution inside of one or more inflatable portions (e.g.,
silicone shells) positioned on the stomach surface of the ring of
the gastric band to adjust the gastric band through a variety of
diameters. As the inflatable portion is inflated it reduces the
stoma of the gastric band and when the inflatable portion is
deflated it increases the stoma of the gastric band. The saline
solution is added to or removed from the inflatable portion via an
access port fixed beneath the skin of the patient in the abdomen on
the rectus muscle sheath using a fine needle to find the right
level of restriction.
[0005] An exemplary gastric band (hydraulic, hydraulic-mechanical
hybrid, or otherwise) may additionally, or alternatively, comprise
an access port coupled with an override mechanism to rapidly remove
fluid or gel from the implant in the event of an emergency.
[0006] Each of the foregoing implants, as well as others, comprise
access ports that may be candidates for various electronics based
enhancements, e.g., an access port fitted with a pressure sensor
and/or an access port that transmits a signal for easier detection
of its location within the body of the patient.
[0007] Furthermore, incorporation of electronic components into
such access ports has not been workable at least in part because of
bioincompatibility. More specifically, these enhancements and the
associated electronics have heretofore caused cytotoxicity and/or
been compromised by the body's interstitial fluids over time.
[0008] Spehr (U.S. Pat. No. 6,240,320) discloses that biocompatible
material such as diamond-like carbon, sapphire, parylene compounds,
diamond, or like materials may be used to coat an exterior of the
electrode member. However, Spehr suffers from the drawback that it
does not use, for example, a tie layer to enhance adhesion of the
biocompatible material. Furthermore, Spehr does not disclose that
several types of coatings can be used in conjunction with each
other to address all of the essential requirements for a successful
long-term function. Such requirements can include, for example,
long-term biocompatibility (10+ years), ability to coat relatively
uniformly and thoroughly over an abrupt topology in a conformal
manner, provide a significant barrier against water molecule
penetration or transmission, utilize a deposition temperature and
other processing parameters which are not too harsh for the
substrate material and the electromechanical device being coated,
non-conductivity of the portion of the coating that directly
contacts an electrical equipment, and ability to stay attached to
the substrate materials and retain its moisture barrier properties
despite (i) abrasion caused by handling during assembly; (ii)
thermal expansion and contraction during shipping and handling and
then due to operation of the device after implantation; (iii)
material aging; (iv) chemical interaction between adjacent
materials; and (v) exposure to sterilization, such as heat,
chemicals or radiation.
[0009] Adamis (U.S. Pat. No. 7,563,255) discloses coating devices
contacting tissue or bio fluid with biocompatible material, such
as, polyethyleneglycol, polyvinylchloride, polycarbonate,
polysulfone, polytetrafluoroethylene, parylene, titanium or the
like, prior to implantation. However, Adamis suffers from the
drawback that it does not use, for example, a tie layer to enhance
adhesion of the biocompatible material. Furthermore, Adamis does
not disclose that several types of coatings can be used as a
multilayered combination to address all of the requirements listed
above.
SUMMARY
[0010] In accordance with exemplary embodiments, the present
invention provides for a biocompatible and biostable medical device
that addresses the needs in the prior art.
[0011] In accordance with exemplary embodiments, the present
invention provides for a medical device, such as an access port
configured to detect the pressure of a fluid within the implant. In
accordance with other exemplary embodiments, the present invention
provides for various novel and nonobvious coating combinations
designed to promote biostability and biocompatibility of
electro-mechanical components in the medical devices, including,
but not limited to, those disclosed herein.
[0012] In one embodiment, the present invention is an access port
for a gastric band including a housing, and an electro-mechanical
component located within the housing, wherein the
electro-mechanical component is coated with a coating
combination.
[0013] In another embodiment, the present invention is an access
port for a gastric band including a penetrable septum defining an
outer wall of a housing, a conduit configured to provide fluid
communication between the penetrable septum and the gastric band, a
pressure sensor in fluid communication with a fluid within the
gastric band, and a printed circuit board assembly connected to the
pressure sensor, wherein the printed circuit board assembly is
coated with a coating combination.
[0014] In yet another embodiment, the present invention is an
access port for a gastric band including a penetrable septum
defining an outer wall of a housing, a conduit configured to
provide fluid communication between the penetrable septum and the
gastric band, and a pressure sensor in fluid communication with a
fluid within the gastric band, wherein the pressure sensor is
coated with a coating combination.
[0015] In still another embodiment, the present invention is a
method for protectively coating a long term medical device
including coating the long term medical device with a tie layer,
and coating the long term medical device with a biostable and
biocompatible material.
[0016] In one embodiment, the present invention is an implantable
medical device including an electro-mechanical component coated
with a coating combination including a tie layer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The exemplary embodiments of the present invention will be
described in conjunction with the accompanying drawing FIGS. in
which like numerals denote like elements and:
[0018] FIG. 1A illustrates an access port comprising a pressure
sensor according to an embodiment of the present invention;
[0019] FIG. 1B illustrates a cross sectional view of an access port
comprising a pressure sensor according to an embodiment of the
present invention;
[0020] FIG. 2 illustrates a printed circuit board assembly coated
with various layers according to an embodiment of the present
invention;
[0021] FIG. 3 illustrates a printed circuit board assembly coated
with various layers according to an embodiment of the present
invention;
[0022] FIG. 4 illustrates a printed circuit board assembly coated
with various layers according to an embodiment of the present
invention;
[0023] FIG. 5 illustrates an electro-mechanical component for a
medical device coated with various layers according to an
embodiment of the present invention; and
[0024] FIG. 6 depicts a process according to an embodiment of the
present invention.
DETAILED DESCRIPTION
[0025] In accordance with exemplary embodiments, the present
invention comprises a biocompatible and biostable medical device,
such as an access port for a gastric band. Persons skilled in the
art will readily appreciate that various aspects of the invention
may be realized by any number of methods and devices configured to
perform the intended functions. Stated differently, other methods
and devices may be incorporated herein to perform the intended
functions. It should also be noted that the drawing FIGS. referred
to herein are not all drawn to scale, but may be exaggerated to
illustrate various aspects of the invention, and in that regard,
the drawing FIGS. should not be construed as limiting. Finally,
although the present invention may be described in connection with
various medical principles and beliefs, the present invention
should not be bound by theory.
[0026] By way of example, the present invention will be described
primarily with reference to hydraulically adjustable gastric bands.
Nevertheless, persons skilled in the art will readily appreciate
that the present invention advantageously may be applied to and one
of the numerous varieties of fluid filled surgical implants
presently comprising, or which may in the future comprise, access
ports. Similarly, while the present invention will be described
primarily with reference to fluid filled surgical implants, persons
skilled in the art will readily appreciate that the present
invention advantageously may be applied to other medical devices,
whether fluid or gel filled.
[0027] In accordance with exemplary embodiments, the present
invention provides for an access port configured to detect the
pressure of a fluid within the implant.
[0028] At the outset, it should be noted that while the present
invention will be described primarily with reference to an access
port, persons skilled in the art will readily appreciate that an
access port is not necessary for detection of the pressure of a
fluid within an implant. Stated differently, the diagnostic and
therapeutic advantages associated with knowing the pressure of a
fluid within an implant, as provided for by the present invention,
may be realized without fluid access to the implant via an access
port.
[0029] As seen in FIGS. 1A and 1B, a medical device, such as an
access port 10 including a pressure sensor 20, and a penetrable
septum 30 is depicted. The penetrable septum 30 can be penetrated
by a needle to allow fluid or gel to be added or removed from the
access port 10. A conduit 40 provides access to a fluid filled
implant such that the addition or removal of fluid to the access
port 10 thereby adds or removes fluid from the fluid filled
implant. The needle can be, for example, a fine needle, a
hypodermic needle, a Huber needle, or any other type of needle
which can supply fluid or gel to the access port 10. In addition, a
tube, instead of a needle can be used. The access port 10 can be
connected, for example, to the fluid filled implant(not shown) and
can be used to supply or remove fluid or gel from the fluid filled
implant. The fluid filled implant can be, for example, a gastric
band, and/or a breast implant (not shown).
[0030] The access port can also optionally include a plate element
50 which is positioned between the penetrable septum 30 and the
pressure sensor 20. The positioning of the plate element 50 serves
to prevent the needle from damaging the pressure sensor 20. The
plate element 50 can be formed, for example, from titanium,
stainless steel, or any other type of material that can protect the
pressure sensor 20 from damage.
[0031] A printed circuit board assembly (PCBA) 60 can be connected,
for example, to the pressure sensor 20. The PCBA 60 is configured
to telemetrically relay a pressure value obtained from the pressure
sensor 20 to an external control unit. The pressure value can
indicate, for example, a pressure of the access port 10 and/or the
fluid filled implant. The pressure sensor 20 can also detect, for
example, a fill volume, a strain, and/or a linear measurement of
the access port 10. The access port 10 can also include, for
example, a housing 70 which can, for example, define a cavity
containing the pressure sensor 20, a portion of the conduit 40, the
plate element 50, and/or the PCBA 60. The penetrable septum 30 can
define, for example, an outer wall of the housing 70.
[0032] The present invention provides for various novel and
nonobvious coating combinations designed to promote biostability
and/or biocompatibility of electro-mechanical components of the
access port or other medical devices, including, but not limited
to, those disclosed herein.
[0033] The term biostable or biostability can mean, for example,
that an implantable device or object is capable of being in contact
with living tissues or organisms and still function within the
expected performance parameters. In one embodiment, a biostable
object or implanted device can still function within the expected
performance parameters, for example, for 10 years or more while
being in contact with the living tissues or organisms.
[0034] The term biocompatible or biocompantibility can mean, for
example, that the implantable device or object is capable of being
in contact with living tissues or organisms without causing harm to
the living tissue or the organism. In one embodiment, a
biocompatible object can be, for example, an object which meets the
U.S. Pharmacopoeia ("USP") Class VI requirements. For example, the
coating combination may be biocompatible over an extended period of
time, such as for 1, 2, 5, 10, 15, 20, or more years.
[0035] In accordance with exemplary embodiments, the present
invention provides for coating combinations that isolate
electro-mechanical components, including, but not limited to,
printed circuit board assemblies, sensors, motors and other
components typical to implantable medical devices, and/or
components forming those objects listed above. The
electro-mechanical components can be purely electrical components,
purely mechanical components, or a hybrid of electrical and
mechanical components.
[0036] In one embodiment, the coating combinations can be, for
example, a multilayer coating.
[0037] Another exemplary coating combination may be able to coat
relatively uniformly and/or thoroughly, over electro-mechanical
components with an abrupt topology. Such electro-mechanical
components can be objects with various abrupt geometries and/or
various surface chemistries and thermal expansion properties such
as a PCBA. Stated differently, an exemplary coating combination is
capable of conformal coating.
[0038] Yet another exemplary coating combination may be a barrier
against water molecule and other moisture penetration and/or
transmission. Qualitatively, an exemplary coating combination may
have a moisture vapor transmission rate (MVTR) roughly equivalent
to that of titanium at approximately 25 .mu.m (0.001 inches)
thickness. Or, stated in terms of water vapor transmission rate
(WVTR), an exemplary coating combination may allow less than 0.001
g/m.sup.2/day. MVTR and WVTR are measures of the passage of water
vapor through a substance.
[0039] Exemplary coating combinations may remain attached to the
substrate material and/or the electro-mechanical component being
coated and retain its moisture barrier properties despite: (i)
abrasion caused by handling during assembly; (ii) thermal expansion
and contraction during shipping, handling, and operation of the
electro-mechanical component after implantation; (iii) material
aging; (iv) chemical interaction between adjacent materials; and
(v) exposure to sterilization such as heat, chemicals or
radiation.
[0040] The deposition temperature and other processing parameters
of other exemplary coating combinations should not be too harsh for
the substrate material and the electro-mechanical component being
coated.
[0041] Depending on the electro-mechanical component being coated,
yet other exemplary coating combinations may be non-conductive or
conductive. For example, where the electro-mechanical components
transmit or receive RF signals, the coating combinations should not
be an RF shield. However, the coating combinations may provide RF
interference protection where appropriate.
[0042] In one embodiment, the coating combination, along with its
coating process, may be reasonable in terms of cost, e.g., no more
than the cost of the underlying electro-mechanical component being
coated.
[0043] In accordance with exemplary embodiments of the present
invention, an exemplary coating combination may comprise one or
more of the following layers depending on the desired coating
combination characteristics: (i) parylene (e.g., Parylene P, or
Parylene M); (ii) diamond like carbon (DLC); (iii) titanium nitride
(TiN); (iv) titanium carbide or silicon nitride; (v) cyclo olefin
copolymer (COC) or cyclo olefin polymer (COP); (vi) epoxy; (vii)
silicone polymer (e.g., primarily resin based (Q or T functional),
linear polymer based, or a hybrid of both); (viii) glass; (ix)
chloro-tri-fluoro-ethylene (CTFE) or
poly-chloro-tri-fluoro-ethylene (PCTFE); (x)
poly-ether-ether-ketone or polysulfone; (xi) acetal or
polyoxymethylene (POM); (xii) polypropylene; (xiii) liquid crystal
polymer (LCP); (xiv) ultra high molecular weight polyethylene
(UHMWPE); and (xv) fluoropolymer acrylate; and (xvi) synthetic
diamond.
[0044] Exemplary methods of applying an exemplary coating
combination comprises one or more of the following steps: (i)
testing the electro-mechanical component for functionality; (ii)
plasma treating the external surfaces of the electro-mechanical
component, e.g., to remove small contaminants and/or enhance
surface adhesion; (iii) packaging the electro-mechanical component
in a particle free environment and package meeting the ISO class 6,
or better, ISO 14644-1 clean room standard (class 1000 under the
FED-STD-209E clean room standard); (iv) opening and handling the
package under clean room conditions; (v) placing the
electro-mechanical component in a coating chamber; and (vi)
applying the coating(s).
[0045] In accordance with exemplary embodiments of the present
invention, an exemplary coating combination may comprise one or
more layers applied with chemical vapor deposition (CVD), physical
vapor deposition (PVD), plasma enhanced chemical vapor deposition
(PECVD), injection molding, compression molding, transfer molding,
film forming, thermoforming, vacuum forming, or dipping. In
addition, other types of layer applications are possible, which can
be used to deposit layers which have conformal properties, adhesive
properties, biocompatible properties, and/or biostable
properties.
[0046] What follows now are several materials used for coating
combinations in accordance with the present invention.
[0047] Parylene P is a Parylene variation with high penetration
properties. However, Parylene P may not necessarily be optimized
for moisture barrier properties. In one embodiment, Parylene P can
be, for example, Parylene HT produced by Specialty Coating Systems
or Parylene diX N produced by Kisco Conformal Coating. Parylene M
is a variation of Parylene with good moisture barrier properties.
However, Parylene M may not have the penetrative properties of
Parylene P. In one embodiment, Parylene M can be, for example,
Parylene C produced by Specialty Coating Systems or Parylene diX D
produced by Kisco Conformal Coating.
[0048] DLC can be a hard coating that can be applied with either a
chemical vapor deposition (CVD) or a physical vapor deposition
(PVD) process. In one embodiment, the CVD version of the DLC
including the Plasma Enhanced CVD (PECVD) can be used due to its
improved conformal characteristics. The CVD version of the DLC can
require a lower process temperature, reducing a likelihood of
damage to the electro-mechanical component being coated. Generally,
DLC can be applied as a first layer to medical devices, or
electro-mechanical components of medical devices that do not have
abrupt topographies. In electro-mechanical components of medical
devices that do have abrupt topographies, the abrupt topographies
can be smoothed out by over-molding (COC/Epoxy, etc.) or
undercoating with some other more conformal coatings (Parylene),
before the DLC is applied. Alternatively, a DLC with improved
conformal characteristics can be used, such as the PECVD.
[0049] TiN can be deposited using CVD or variations of the CVD, and
is generally biocompatible and a good moisture barrier. Some
versions of TiN can be deposited in a CVD process with temperatures
below 60.degree. C., which makes it safe for most
electro-mechanical components. TiN can be somewhat conductive, and
may be beneficial for electrostatic discharge (ESD) protection and
electromagnetic interference (EMI) protection.
[0050] Titanium carbide, silicon nitride, and a number of metallic
thin coatings can be used as moisture barriers due to their low
processing temperatures. Any biocompatibility issues can be
addressed by over-coating. Their conductive properties may also be
beneficial in certain applications, such as for electrostatic
discharge (ESD) protection and electromagnetic interference (EMI)
protection.
[0051] COC, COP, or epoxy may not be as thin as Parylene or DLC,
but they can provide good barriers against moisture migration. In
addition, this over-mold or coverage can also allow a flat surface
to be formed over the electro-mechanical component, even when the
electro-mechanical component has an abrupt topography. The flat
surfaces increases the likelihood that a uniform DLC or Parylene
overcoat can be formed. The epoxy can be applied by a casting or
pouring process, while the COC can be applied using injection
molding.
[0052] Silicone polymer materials may be primarily resin based (Q
or T functional), linear polymer based, or any combination of the
two. The silicone polymer materials may be long term-term
biocompatible and can smooth out any abrupt topography in the
electro-mechanical component. In addition, the silicone polymer
materials can provide good adhesion to the subsequent coating
options such as Parylene and DLC.
[0053] Glass can be applied in a casting or over-mold process when
the high temperature of the molten glass does not damage the
substrate or the electro-mechanical component that it is coating.
However, if temperatures typically over 260.degree. C. are not
acceptable, a glass encapsulation process can be used. The glass
encapsulation process can include, for example, shrinking a thin
glass layer over the electro-mechanical component, or making a
two-part glass housing in a casting process, fitting them over the
electro-mechanical component, and then sealing the seams with a
glass-to-glass sealing. Glass can provide a good moisture barrier,
and many grades of glass are biocompatible. In addition, glass can
offer a relatively flat surface for further coating layers if
necessary.
[0054] CTFE or PCTFE can have low friction, inertness, and improved
moisture barrier properties. In one embodiment, Aclar.RTM. RX by
Honeywell.RTM. can be used. Although it may be difficult to
injection mold the CTFE or PCTFE, the CTFE or PCTFE material can be
applied as a film over the electro-mechanical component such as
through thermoforming. In thermoforming, the film of the CTFE or
PCTFE can be heated and pressure sealed, or adhesively bonded.
[0055] Poly-ether-ether-ketone (PEEK) and polysulfone film or resin
can possess desirable biocompatibility properties due to its
long-term implantable grades. Due to their high temperature
requirements, PEEK and polysulfone film or resin may be suitable
for high temperature electro-mechanical components, or
electro-mechanical components which do not require the PEEK and
polysulfone film or resin to be over-molded over the
electro-mechanical component. Although the PEEK and polysulfone
film or resin may have reduced moisture barrier properties, they
can be thermoformed over the electro-mechanical component, for
example, to smooth out the abrupt topography in preparation for a
Parylene or DLC layer.
[0056] Although POM has reduced moisture barrier properties, it can
have biocompatible grades and can be injection molded, making it a
good choice for reducing the abrupt topography in an over-mold.
[0057] Polypropylene can provide a good moisture barrier and can be
injection molded at relatively low temperatures. Thus,
polypropylene can be beneficial for reducing the abrupt topography
in an over-mold for the electro-mechanical component while avoiding
heat damage to the electro-mechanical component. In addition it can
be relatively low cost for any cost-sensitive applications. Any
biocompatibility issues can be addressed by over-coating the
polypropylene layer with DLC or Parylene layers.
[0058] LCP can be injection moldable and can penetrate tight areas.
It can also be molded in thin sections over the electro-mechanical
component due to its desirable rheological behavior during
injection molding. Thus, although it may have reduced moisture
barrier properties and reduced long-term implantable qualities, the
liquid crystal polymer may be effective in reducing abrupt
geometries in the electro-mechanical component.
[0059] Ultra high molecular weight polyethylene has good abrasion
resistance and relatively good moisture barrier properties. It can
also be long-term biocompatible. The ultra high molecular weight
polyethylene can be compression molded instead of injection molded,
and also applied as a thin film similar to PCTFE, PEEK, or
polysulfone, but does not require as high as a temperature as such
materials for thermoforming.
[0060] Fluoropolymer acrylate coating is applied as a coating in a
dipping process, where the electro-mechanical component is dipped
into an organic solvent containing fluoropolymer acrylate. This
coating is typically used as protective barrier layer on the
electro-mechanical component, such as when the electro-mechanical
component is an electrical component. Fluoropolymer acrylate can
have relatively good moisture barrier properties.
[0061] In the coating combinations, a tie layer can also be used.
The tie layer can be formed, for example, from a material which is
conformal and has good adhesive properties. In one embodiment, the
tie layer can be, for example, AdPro Plus produced by Specialty
Coating Systems.
[0062] In one embodiment, the coating combinations can include a
first layer formed on top of an electro-mechanical component and
which has conformal and/or adhesive properties. The first layer can
be, for example, a tie layer. A second layer can be formed on top
of the first layer. The second layer can have biocompatible and
biostable properties. The second layer can be, for example, the
outermost layer which contacts the body of a patient. If the second
layer does not have moisture barrier properties, additional layers
can be formed between the first layer and the second layer with
moisture barrier properties. In addition, additional layers can be
formed between the first layer and the second layer with additional
desirable properties.
[0063] What follows are coating combinations which use some of the
materials listed above, according to various embodiments of the
present invention:
[0064] Coating Combination 1
[0065] Layer 1--Tie layer which enhances adhesion of Parylene.
[0066] Layer 2--Parylene P with crevice penetration properties at a
thickness of approximately 10 .mu.m to 100 .mu.m.
[0067] Layer 3--Parylene M at a thickness of approximately 10 .mu.m
to 100 .mu.m.
[0068] Coating Combination 2
[0069] Layers 1 through 3--same as coating combination 1.
[0070] Layer 4--DLC at a thickness of approximately 0.02 .mu.m to
0.2 .mu.m.
[0071] Coating Combination 3
[0072] Layer 1--Tie layer which enhances adhesion of Parylene.
[0073] Layer 2--Parylene P with crevice penetration properties at a
thickness of approximately 10 .mu.m to 100 .mu.m.
[0074] Layer 3--Epoxy (cast as thin as possible to smooth out
abrupt topographies).
[0075] Layer 4--Parylene M at a thickness of 10 .mu.m to 100
.mu.m.
[0076] Coating Combination 4
[0077] Layers 1 through 4--Same as coating combination 3.
[0078] Layer 5--DLC at a thickness of approximately 0.02 .mu.m to
0.2 .mu.m or more.
[0079] Coating Combination 5
[0080] Same as coating combination 3 but replace Epoxy with COC,
applied in an injection molding tool.
[0081] Coating Combination 6
[0082] Same as coating combination 4 but replace Epoxy with COC,
applied in an injection molding tool.
[0083] Coating Combination 7
[0084] Same as coating combination 5, but instead of COC, use any
of glass, chloro-tri-fluoro-ethylene or
poly-chloro-tri-fluoro-ethylene, poly-ether-ether-ketone or
polysulfone, polyoxymethylene, polypropylene, liquid crystal
polymer, ultra high molecular weight polyethylene, and
fluoropolymer acrylate.
[0085] Coating Combination 8
[0086] Same as coating combination 6, but instead of COC, use any
of glass, chloro-tri-fluoro-ethylene or
poly-chloro-tri-fluoro-ethylene, poly-ether-ether-ketone or
polysulfone, polyoxymethylene, polypropylene, liquid crystal
polymer, ultra high molecular weight polyethylene, and
fluoropolymer acrylate.
[0087] What follows now are several embodiments of coating
combinations comprising silicone polymer in accordance with the
present invention. In exemplary embodiments, silicone polymer is
formulated to cure from a specified uncured state to a specified
cured state. The uncured state would range from low to moderate
viscosity (1-1000 cp), used to control the coating process, and the
cured state would be in a range of hardness (Shore A 20-100). An
exemplary cure mechanism is a platinum system, but other systems
may be suitable as well, for example, a condensation or peroxide
cure system.
[0088] Coating Combination 9
[0089] Layer 1--A low durometer (softer) silicone applied directly
to the substrate in a relatively thicker (higher viscosity)
coating.
[0090] Layer 2--Parylene, DLC, TiN, PCTFE film, and/or combinations
of the materials listed.
[0091] Coating Combination 10
[0092] Layer 1--A high durometer (firmer) silicone applied directly
to the substrate in a relatively thinner (lower viscosity)
coating.
[0093] Layer 2--Same as coating combination 9.
[0094] Coating Combination 11
[0095] Layer 1--A low durometer (softer) silicone applied directly
to the substrate in a relatively thicker (higher viscosity)
coating.
[0096] Layer 2--A high durometer (firmer) silicone applied directly
to the substrate in a relatively thinner (lower viscosity)
coating.
[0097] Layer 3--Same as coating combination 9.
[0098] Coating Combination 12
[0099] Layer 1--A primer or tie layer which may be composed of
silicone prime (resin), or any other material designed to increase
adhesion.
[0100] Layer 2--A low durometer (softer) silicone applied directly
to the substrate in a relatively thicker (higher viscosity)
coating.
[0101] Layer 3--A high durometer (firmer) silicone applied directly
to the substrate in a relatively thinner (lower viscosity)
coating.
[0102] Layer 4--Same as coating combination 9.
[0103] Coating Combination 13
[0104] Layer 1--Same as coating combination 1.
[0105] Layer 2--A low durometer (softer) silicone applied directly
to the substrate in a relatively thicker (higher viscosity)
coating.
[0106] Layer 3--A high durometer (firmer) silicone applied directly
to the substrate in a relatively thinner (lower viscosity)
coating.
[0107] Layer 4--Same as coating combination 9.
[0108] Coating Combination 14
[0109] Layer 1--A primer or tie layer which may be composed of
silicone prime (resin), or any other material designed to increase
adhesion.
[0110] Layer 2--A single layer of silicone formulated to provide
necessary, mechanical, thermal, and chemical properties.
[0111] Layer 3--Same as coating combination 9.
[0112] Coating Combination 15
[0113] Layer 1--Same as coating combination 1.
[0114] Layer 2--A single layer of silicone formulated to provide
necessary, mechanical, thermal, and chemical properties.
[0115] Layer 3--Same as coating combination 9.
[0116] Coating Combination 16
[0117] Layer 1--A layer of silicone with conformal and adhesive
properties.
[0118] Layer 2--A layer including materials which have moisture
barrier properties, such as DLC, Parylene M, TiN, or PCTFE.
[0119] Layer 3--A layer of silicone with biocompatible and
biostable properties.
[0120] For example, in one embodiment as seen in FIG. 2, a PCBA 60
can be coated by a layer 62 and/or a layer 64. The layer 62 and/or
the layer 64 can form, for example, the coating combinations 1-15.
The layer 62 can be, for example, the Layer 1 in the coating
combinations 1-15. The layer 64 can be, for example, the other
layers, in the coating combinations 1-15. The PCBA 60, which is
coated, can also be seen in FIGS. 3 and 4. In FIGS. 3 and 4, all
sensitive electro-mechanical components in the PCBA 60 are coated
by a coating combination 66 except for the sensing element which is
already biocompatible and/or biostable by choice of its
construction material or by a thin layer of coating including but
not limited to DLC or TiN. The sensing element can be, for example,
a pressure sensing element.
[0121] In addition, although a PCBA 60 is depicted in FIGS. 2, 3
and 4, any medical device can be coated. The medical device can be,
for example, an access port fitted with a pressure sensor which
measures the pressure in the saline solution, an access port that
transmits a signal for easier detection of its location in the
body, a pump that controls an amount of fluid in the gastric band,
any long term medical device such as a device which is implanted
for a long term (e.g. 10 years or more) within a body, and/or any
electro-mechanical components of the objects listed above. In one
embodiment, the medical device can also include electro-mechanical
components and/or software for detecting breaches to the coating
combinations. The medical device can include, for example, an
onboard diagnostic tool to detect such breaches to the coating
combinations.
[0122] In one embodiment, electro-mechanical components of a
medical device, such as a long term medical device, can be coated.
For example, an electro-mechanical component 80 of a long term
medical device can be coated as seen in FIG. 5. The
electro-mechanical component 80 can be coated with the layer 62
and/or the layer 64.
[0123] In one embodiment, the one or more coatings or layers may be
applied to various implantable medical devices such as an access
port, a breast implant, a cardiac rhythm management device, a
pacemaker, a cardioverter, a defibrillator, a neurostimulator, an
activity sensor, a pressure sensor, a multi-sensor device, a drug
delivery pump or device, a heart monitor, a respiratory monitor, an
artificial kidney or other artificial organs aside from the heart,
orthopedic implants with electronics incorporating stress, pressure
or force sensors. In one embodiment, the various implantable
medical devices are medical devices which may come in contact with
interstitial body fluids, but do not come in contact with
blood.
[0124] The foregoing disclosure is illustrative of the present
invention and is not to be construed as limiting the invention.
Although one or more embodiments of the invention have been
described, persons skilled in the art will readily appreciate that
numerous modifications could be made without departing from the
spirit and scope of the present invention. By way of mere example,
persons skilled in the art will readily appreciate that the novel
and nonobvious coating combinations designed to promote
biostability described herein advantageously may be applied not
just to surgical implants, but to any device or device component
having biostability as a design requirement. In sum, it should be
understood that all such modifications are intended to be included
within the scope of the invention.
[0125] The terms "a," "an," "the," and similar referents used in
the context of describing the present invention (especially in the
context of the following claims) are to be construed to cover both
the singular and the plural, unless otherwise indicated herein or
clearly contradicted by context. Recitation of ranges of values
herein is merely intended to serve as a shorthand method of
referring individually to each separate value falling within the
range. Unless otherwise indicated herein, each individual value is
incorporated into the specification as if it were individually
recited herein. All methods described herein can be performed in
any suitable order unless otherwise indicated herein or otherwise
clearly contradicted by context. The use of any and all examples,
or exemplary language (e.g., "such as") provided herein is intended
merely to better illuminate the present invention and does not pose
a limitation on the scope of the present invention otherwise
claimed. No language in the specification should be construed as
indicating any non-claimed element essential to the practice of the
present invention.
[0126] Groupings of alternative elements or embodiments of the
invention disclosed herein are not to be construed as limitations.
Each group member may be referred to and claimed individually or in
any combination with other members of the group or other elements
found herein. It is anticipated that one or more members of a group
may be included in, or deleted from, a group for reasons of
convenience and/or patentability. When any such inclusion or
deletion occurs, the specification is deemed to contain the group
as modified thus fulfilling the written description of all Markush
groups used in the appended claims.
[0127] Certain embodiments of this invention are described herein,
including the best mode known to the inventors for carrying out the
invention. Of course, variations on these described embodiments
will become apparent to those of ordinary skill in the art upon
reading the foregoing description. The inventor expects skilled
artisans to employ such variations as appropriate, and the
inventors intend for the invention to be practiced otherwise than
specifically described herein. Accordingly, this invention includes
all modifications and equivalents of the subject matter recited in
the claims appended hereto as permitted by applicable law.
Moreover, any combination of the above-described elements in all
possible variations thereof is encompassed by the invention unless
otherwise indicated herein or otherwise clearly contradicted by
context.
[0128] Furthermore, certain references have been made to patents
and printed publications throughout this specification. Each of the
above-cited references and printed publications are individually
incorporated herein by reference in their entirety.
[0129] Specific embodiments disclosed herein may be further limited
in the claims using consisting of or consisting essentially of
language. When used in the claims, whether as filed or added per
amendment, the transition term "consisting of" excludes any
element, step, or ingredient not specified in the claims. The
transition term "consisting essentially of" limits the scope of a
claim to the specified materials or steps and those that do not
materially affect the basic and novel characteristic(s).
Embodiments of the invention so claimed are inherently or expressly
described and enabled herein.
[0130] In closing, it is to be understood that the embodiments of
the present invention disclosed herein are illustrative of the
principles of the present invention. Other modifications that may
be employed are within the scope of the present invention. Thus, by
way of example, but not of limitation, alternative configurations
of the present invention may be utilized in accordance with the
teachings herein. Accordingly, the present invention is not limited
to that precisely as shown and described.
* * * * *