Note: Descriptions are shown in the official language in which they were submitted.
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A MEMBRANE SWITCH WITH A GAS PERMEABLE,
LIQUID IMPERMEABLE LAYER
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to App. Ser. No. 61/782,131,
entitled "Devices,
Systems and Methods for a Membrane Switch with Permeable Layer," filed March
14, 2013,
the entire contents of which are hereby incorporated by reference.
FIELD OF THE INVENTION
[0002] The present disclosure generally relates to devices and systems
relating to
membrane switches. More specifically, a membrane switch is provided that may
be exposed
to sterilization processes, including vacuum processes without damaging the
switch.
DESCRIPTION OF THE RELATED ART
[0003] Generally, various embodiments of the present invention comprise an
improved
membrane switch. As the skilled artisan will readily recognize, membrane
switches are well
known. Thus, the known membrane switch may be described as "a momentary switch
device
in which at least one contact is on, or made of, a flexible substrate.."
[0004] The known membrane switch typically has 4 or more layers but may
have more or
fewer. The top layer of a membrane switch is the graphic interface between the
user and the
machine. The other critical layer is a printed circuit. This can also be a
flex circuit made of
copper and polyimide material. The layers are normally assembled using
pressure sensitive
adhesives although inexpensive designs can be held together through other
mechanical means
such as a keyboard housing. Contact between two traces can be made through a
printed
shorting pad or through a metal dome that stands on legs.
[0005] Membrane switches may be backlit in certain embodiments. There are
three
standard methods for back lighting membrane switches.
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[0006] The first option is using Light Emitting Diodes (LEDs) to back
light. However,
LEDs create bright spots and are not suitable for overall back lighting of a
panel, but rather as
indicator lights. LEDs can either be surface-mounted to the circuit layer or
be placed on a
separate LED layer.
[0007] A second option is optical fiber. In a typical design, two or more
layers of woven
fiber-optic cloth are used to form a rectangular light-emitting area. The
fibers coming off one
end are then bundled into a circular ferrule and coupled to one or more LED
light sources.
Remote light sources offer 10,000 to 100,000 hours of life. Optical fibers are
not affected by
extremes in humidity (0% to 100%) or temperature (-40 to +85 deg C).
[0008] The third standard option is to use electroluminescent (EL) lamps.
They are lower
priced compared to fiber optics and offer additional design flexibility. The
color of light
emitted from an EL lamp can vary depending on the phosphors that are used.
Some common
colors are blue/green and yellow/green, white, blue and orange. EL lamps have
a half life of
approximately 3000-8000 hours depending upon the quality of the phosphor. Once
they
reach their half life, the brightness starts to fade rapidly. EL lamps are
thus not a good choice
if the lamp is on for an extended period of time. Fading or flashing could
double the life of
the lamp.
[0009] As noted herein, applications for layered membrane switches are
numerous,
including but certainly not limited to rotational atherectomy systems.
[0010] Known applications of layered membrane switches include microwave
oven
panel, air conditioner control panel, TV remote control etc. Tactile feedback
of keys can be
provided by embossing the top PET layer or embedding metal snap domes,
polyester domes
or forming the graphic layer.
[0011] The benefits of membrane switches include ease of cleaning, sealing
ability and
their low profile. Membrane switch can be used together with other control
systems such as
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touch screens, keyboards, lighting, and they can also be complicated like the
membrane
keyboards and switch panels in mobiles and computers.
[0012] Known membrane switches are, however, vulnerable during certain
processes,
e.g.,. sterilization and the like where vacuum processing is required. The
forces generated
during, e.g., vacuum processing, are known to damage layered membrane
switches. In
addition, exposure of the known membrane switches to fluids is a problem
resulting in
damage to the membrane switch. These vulnerabilities limit the applications in
which
layered membrane switches may be implemented.
[0013] One environment in which membrane switches may be incorporated
includes,
without any limitation, rotational atherectomy. A variety of techniques and
instruments have
been developed for use in the removal or repair of tissue in arteries and
similar body
passageways. A frequent objective of such techniques and instruments is the
removal of
atherosclerotic plaques in a patient's arteries. Atherosclerosis is
characterized by the buildup
of fatty deposits (atheromas) in the intimal layer (under the endothelium) of
a patient's blood
vessels. Very often over time, what initially is deposited as relatively soft,
cholesterol-rich
atheromatous material hardens into a calcified atherosclerotic plaque. Such
atheromas restrict
the flow of blood, and therefore often are referred to as stenotic lesions or
stenoses, the
blocking material being referred to as stenotic material. If left untreated,
such stenoses can
cause angina, hypertension, myocardial infarction, strokes and the like.
[0014] Rotational atherectomy procedures have become a common technique for
removing such stenotic material. Such procedures are used most frequently to
initiate the
opening of calcified lesions in coronary arteries. Most often the rotational
atherectomy
procedure is not used alone, but is followed by a balloon angioplasty
procedure, which, in
turn, is very frequently followed by placement of a stent to assist in
maintaining patentcy of
the opened artery. For non-calcified lesions, balloon angioplasty most often
is used alone to
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open the artery, and stents often are placed to maintain patentcy of the
opened artery. Studies
have shown, however, that a significant percentage of patients who have
undergone balloon
angioplasty and had a stent placed in an artery experience stent restenosis-
i.e., blockage of
the stent which most frequently develops over a period of time as a result of
excessive growth
of scar tissue within the stent. In such situations an atherectomy procedure
is the preferred
procedure to remove the excessive scar tissue from the stent (balloon
angioplasty being not
very effective within the stent), thereby restoring the patentcy of the
artery.
[0015] Several kinds of rotational atherectomy devices have been developed
for
attempting to remove stenotic material. In one type of device, such as that
shown in U.S. Pat.
No. 4,990,134 (Auth), a burr covered with an abrasive abrading material such
as diamond
particles is carried at the distal end of a flexible drive shaft The burr is
rotated at high speeds
(typically, e.g., in the range of about 150,000-190,000 rpm) while it is
advanced across the
stenosis. As the burr is removing stenotic tissue, however, it blocks blood
flow. Once the burr
has been advanced across the stenosis, the artery will have been opened to a
diameter equal to
or only slightly larger than the maximum outer diameter of the burr.
Frequently more than
one size burr must be utilized to open an artery to the desired diameter.
[0016] U.S. Pat. No. 5,314,438 (Shturman) discloses another atherectomy
device having
a drive shaft with a section of the drive shaft having an enlarged diameter,
at least a segment
of this enlarged surface being covered with an abrasive material to define an
abrasive
segment of the drive shaft. When rotated at high speeds, the abrasive segment
is capable of
removing stenotic tissue from an artery. Though this atherectomy device
possesses certain
advantages over the Auth device due to its flexibility, it also is capable
only of opening an
artery to a diameter about equal to the diameter of the enlarged abrading
surface of the drive
shaft since the device is not eccentric in nature.
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[0017] U.S. Pat. No. 6,494,890 (Shturman) discloses a known atherectomy
device having
a drive shaft with an enlarged eccentric section, wherein at least a segment
of this enlarged
section is covered with an abrasive material. When rotated at high speeds, the
abrasive
segment is capable of removing stenotic tissue from an artery. The device is
capable of
opening an artery to a diameter that is larger than the resting diameter of
the enlarged
eccentric section due, in part, to the orbital rotational motion during high
speed operation.
Since the enlarged eccentric section comprises drive shaft wires that are not
bound together,
the enlarged eccentric section of the drive shaft may flex during placement
within the stenosis
or during high speed operation. This flexion allows for a larger diameter
opening during high
speed operation, but may also provide less control than desired over the
diameter of the artery
actually abraded. In addition, some stenotic tissue may block the passageway
so completely
that the Shturman device cannot be placed therethrough. Since Shturman
requires that the
enlarged eccentric section of the drive shaft be placed within the stenotic
tissue to achieve
abrasion, it will be less effective in cases where the enlarged eccentric
section is prevented
from moving into the stenosis. The disclosure of U.S. Pat. No. 6,494,890 is
hereby
incorporated by reference in its entirety.
[0018] U.S. Pat No. 5,681, 336 (Clement) provides a known eccentric tissue
removing
burr with a coating of abrasive particles secured to a portion of its outer
surface by a suitable
binding material. This construction is limited, however because, as Clement
explains at CoI.
3, lines 53-55, that the asymmetrical burr is rotated at "lower speeds than
are used with high
speed ablation devices, to compensate for heat or imbalance." That is, given
both the size and
mass of the solid burr, it is infeasible to rotate the burr at the high speeds
used during
atherectomy procedures, i.e., 20,000-200,000 rpm. Essentially, the center of
mass offset from
the rotational axis of the drive shaft would result in development of
significant centrifugal
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force, exerting too much pressure on the wall of the artery and creating too
much heat and
excessively large particles.
[0019] Generally atherectomy devices utilize a guidewire that extends
distally from the
distal end of the drive shaft to assist a practitioner in guiding the device
through the patient's
vasculature and to a desired location for removal of plaque or fatty tissue
buildup. A
guidewire, whether a new wire or a replacement wire, must be loaded into the
atherectomy
device such that it is controllable from a proximal end of the atherectomy
device by the
practitioner. Prior references that disclose methods and devices for loading a
tubular member
into a device include U.S. Pat. No. 3,370,150 (Nordgren); U.S. Pat. No.
4,851,694 (Rague);
U.S. Pat. No. 5,540,649 (Bonnell); U.S. Pat. No. 5,779,623 (Bonnell); U.S. Pat
No. 6,828,523
(Gysi); U.S. Pat. Pub. No. 2004/0254566 (Plicchi); U.S. Pat. Pub. No.
2006/0161043
(Neumann); U.S. Pat. Pub. No. 2007/0299305 (Murakami); and U.S. 2009/0326449
(Wang),
all of which are incorporated herein by reference. These prior art disclosures
generally teach
in relevant part, devices and systems enabling two-way axial translation of a
tubular member
using motorized rollers wherein one of the rollers is spring loaded (biased
toward the
opposite rollers) to increase fit and contact with the tubular member.
Additionally, U.S. Pat.
Pub. No. 2010/0234873 (Nagano), which is incorporated herein by reference,
discloses a
drive device for driving a linear body having flexibility, wherein the force
applied to drive the
linear body only in an axial direction and the pressure applied to a spring is
determined and
adjusted by a control unit. U.S. Pat. Pub. No. 2012/0232476 (Bhat), which is
incorporated
herein by reference, discloses a steering system having two radially
oppositely arranged
driving wheels for steering a tubular member, the drive wheels having a
plurality of rollers
distributed around a wheel rotation axis of the drive wheels. U.S. Pat. No.
7,955,252
(Suzuki), which is incorporated herein by reference, discloses a treatment
tool insertion-
rctraction and rotating device, the device having a holding member disposed
between the
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treatment tool and a pair of rollers. U.S. Pat. No. 6,786,727 (Irion), which
is incorporated
herein by reference, discloses a holding device with a fixed gear arrangement
with bevel
gears to apply a fixed pressure onto an instrument. U.S. Pat. Pub.
2012/0071821 (Yu), which
is incorporated herein by reference, discloses a device and method for
manipulating an
elongated member by actuating rotary members in opposite linear directions to
generate
rotational motion and actuating rotary members in opposite rotational
directions to generate
linear motion.
[0020] Thus, a need exists in the art generally for a layered membrane
switch and further
comprising a gas permeable, but liquid impermeable, polymer. This polymer
solves several
nagging problems currently experienced by layered membrane switches. More
specifically,
rotational atherectomy devices and systems have need of a layered membrane
switch and
further comprising a gas permeable, but liquid impermeable, polymer. The
present invention
addresses these, among other, needs.
BRIEF SUMMARY OF THE INVENTION
[0021] The present system is directed in various embodiments to membrane
switches
generally. More specifically, a membrane switch is provided that may be
exposed to
sterilization processes, including vacuum processes without damaging the
switch. Thus, the
inventive membrane switch comprises a gas permeable, liquid impermeable
membrane layer.
In various embodiments, the membrane switch may be used in rotational
atherectomy
systems. However, the membrane switch of the present invention has wide
application
beyond rotational atherectomy.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 illustrates an exploded view of one embodiment of the present
hwention.
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DETAILED DESCRIPTION
[0023] While the invention is amenable to various modifications and
alternative forins,
specifics thereof are shown by way of example in the drawings and described in
detail herein.
It should be understood, however, that the intention is not to limit the
invention to the
particular embodiments described. On the contrary, the intention is to cover
all modifications,
equivalents, and alternatives falling within the spirit and scope of the
invention.
[0024] The present invention provides a layered membrane switch and further
comprising
a gas permeable, but liquid impermeable, membrane layer. This membrane layer
may
comprise a polymer and solves several nagging problems currently experienced
by layered
membrane switches.
[0025] First, the present invention allows for the layered membrane switch
with the gas
permeable and liquid impermeable membrane layer to be exposed to processes
such as
sterilization and/or vacuum processes that create forces that would otherwise
damage known
layered membrane switches.
[0026] Second, the present invention allows the layered membrane switch
with gas
permeable and liquid impermeable membrane layer to be exposed to liquids. Such
exposure
damages currently known layered membrane switches.
[0027] Third, the present invention allows gases to penetrate the layered
membrane
switch.
[0028] Among other things, the addition of the gas permeable and liquid
impermeable
membrane layer to the layered membrane switch to create the present invention
allows
equalization of internal switch pressures with the external pressures outside
of the switch,
while resisting exposure of the internal switch membrane materials and
components to
damaging fluids.
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[0029] Various embodiments of the present invention comprising a membrane
switch
may be incorporated into the control electronics of a rotational atherectomy
system as
described generally in U.S. Pat. No. 6,494,890, entitled "ECCENTRIC ROTATIONAL
ATHERECTOMY DEVICE," which is incorporated herein by reference. Additionally,
the
disclosure of the following co-owned patents or patent applications are herein
incorporated
by reference in their entireties: U.S. Pat. No. 6,295,712, entitled
"ROTATIONAL
ATHERECTOMY DEVICE"; U.S. Pat No. 6,132,444, entitled "ECCENTRIC DRIVE
SHAFT FOR ATHERECTOMY DEVICE AND METHOD FOR MANUFACTURE"; U.S.
Pat. No. 6,638,288, entitled "ECCENTRIC DRIVE SHAFT FOR ATHERECTOMY
DEVICE AND METHOD FOR MANUFACTURE"; U.S. Pat. No. 5,314,438, entitled
"ABRASIVE DRIVE SHAFT DEVICE FOR ROTATIONAL ATHERECTOMY"; U.S. Pat.
No. 6,217,595, entitled "ROTATIONAL ATHERECTOMY DEVICE"; U.S. Pat. No.
5,554,163, entitled "ATHERECTOMY DEVICE"; U.S. Pat. No. 7,507,245, entitled
"ROTATIONAL ANGIOPLASTY DEVICE WITH ABRASIVE CROWN"; U.S. Pat. No.
6,129,734, entitled "ROTATIONAL ATHERECTOMY DEVICE WITH RADIALLY
EXPANDABLE PRIME MOVER COUPLING"; U.S. Pat. No. 8,597,313, entitled
"ECCENTRIC ABRADING HEAD FOR HIGH-SPEED ROTATIONAL ATHERECTOMY
DEVICES"; U.S. Pat No. 8,439,937, entitled "SYSTEM, APPARATUS AND METHOD
FOR OPENING AN OCCLUDED LESION"; U.S. Pat. Pub. No. 2009/0299392, entitled
"ECCENTRIC ABRADING ELEMENT FOR HIGH-SPEED ROTATIONAL
ATHERECTOMY DEVICES"; U.S. Pat. Pub. No. 2010/0198239, entitled "MULTI-
MATERIAL ABRADING HEAD FOR ATHERECTOMY DEVICES HAVING
LATERALLY DISPLACED CENTER OF MASS"; U.S. Pat. Pub. No. 2010/0036402,
entitled "ROTATIONAL ATHERECTOMY DEVICE WITH PRE-CURVED DRIVE
SHAFT"; U.S. Pat. Pub. No. 2009/0299391, entitled "ECCENTRIC ABRADING AND
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CUTTING HEAD FOR HIGH-SPEED ROTATIONAL ATHERECTOMY DEVICES"; U.S.
Pat. Pub. No. 2010/0100110, entitled "ECCENTRIC ABRADING AND CUTTING HEAD
FOR HIGH-SPEED ROTATIONAL ATHERECTOMY DEVICES"; U.S. Design Pat. No.
D610258, entitled "ROTATIONAL ATHERECTOMY ABRASIVE CROWN"; U.S. Design
Pat. No. D6107102, entitled "ROTATIONAL ATHERECTOMY ABRASIVE CROWN";
U.S. Pat. Pub. No. 2009/0306689, entitled "BIDIRECTIONAL EXPANDABLE HEAD FOR
ROTATIONAL ATHERECTOMY DEVICE"; U.S. Pat. Pub. No. 2010/0211088, entitled
"ROTATIONAL ATHERECTOMY SEGMENTED ABRADING HEAD AND METHOD
TO IMPROVE ABRADING EFFICIENCY"; U.S. Pat. Pub. No. 2013/0018398, entitled
"ROTATIONAL ATHERECTOMY DEVICE WITH ELECTRIC MOTOR"; and U.S. Pat.
No. 7,666,202, entitled "ORBITAL ATHERECTOMY DEVICE GUIDE WIRE DESIGN."
It is contemplated by this invention that the features of onc or more of the
embodiments of
the present invention may be combined with one or more features of the
embodiments of
atherectomy devices described therein; specifically the membrane switch of the
present
invention may be incorporated into the handle electronics and control systems
of the
rotational atherectomy systems described in the references above.
[0030] FIG. 1 illustrates an exploded view of an exemplary embodiment 100
of the
present invention, with the arrows indicating the adhesion of adjacent layers
following
assembly. Thus, the following layers are provided, as illustrated from top
layer 110 to the
bottom layer 180, each layer affixed to the most adjacent layer(s) with
adhesives or the
equivalent and as will be readily understood by the skilled artisan:
[0031] Graphic overlay layer 110, illustrated as the top most layer.
[0032] Graphic mounting layer 120, affixed to the graphic overlay layer 110
and further
comprising two actuator cutouts 122.
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[0033] Dome holder layer 130, affixed to the graphic mounting layer 120.
Thus, graphic
mounting layer 120 is effectively sandwiched between adjacent graphic overlay
layer 110 and
adjacent dome holder layer 130.
[0034] Dome spacers 140, as illustrated two dome spacers 140, affixed to
the tail filler
layer 150, tail filler layer 150 further comprising two dome spacer cutouts
152, wherein each
dome spacer 140 is aligned with a dome spacer cutout 152, and wherein the tail
filler layer
150 is affixed to the dome holder layer 130.
10035] Actuable circuit layer 160 comprising required actuable switching
circuitry as
known by the skilled artisan, wherein the dome spacer cutouts 152 and dome
spacers 140 are
aligned with actuable circuitry, the circuit layer 160 affixed to the tail
filler layer 150.
[0036] Gas permeable and liquid impermeable membrane layer 170, affixed to
the
adjacent circuit layer 160 and to the adjacent mounting adhesive layer 180.
Thus, circuit
layer 160, as illustrated is sandwiched between the tail filler layer 150 and
the gas permeable
and liquid impermeable membrane layer 170.
[0037] Mounting adhesive layer 180, affixed to the adjacent gas permeable,
liquid
impermeable membrane layer 170. Accordingly, the gas permeable, liquid
impermeable
membrane layer 170 is sandwiched between adjacent mounting adhesive layer 180
and
adjacent circuit layer 160.
As illustrated, the exemplary and assembled membrane switch 100 thus
comprises:
a graphic overlay layer 110;
a graphic mounting layer 120 disposed below the graphic overlay layer 110 and
affixed
thereto;
a dome holder layer 130 disposed below the graphic mounting layer 120 and
affixed thereto;
a tail filler layer 150 disposed below the dome holder layer 130 and affixed
thereto;
an actuable circuit layer 160 disposed below the tail filler layer 150 and
affixed thereto;
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a gas permeable, liquid impermeable membrane layer 170 disposed below the
actuable circuit
layer 160 and affixed thereto; and
a mounting adhesive layer 180 disposed below the gas permeable, liquid
impermeable
membrane layer 170 and affixed thereto.
[0038]
[0039] The skilled artisan will readily recognize alternative arrangements
for the
exemplary membrane switch 100, including modifying the location of the gas
permeable,
liquid impermeable membrane layer 170 within the exemplary switch 100, as well
as
providing more than one gas permeable, liquid impermeable membrane layer 170
within
exemplary switch 100. Each such alternative is within the scope of the present
invention.
[0040] Turning to the gas permeable, liquid impermeable membrane layer 170,
the
material utilized for membrane layer 170 must exhibit the properties of being
both liquid
impermeable and gas permeable. Thin expanded plastic membranes may exhibit
these two
properties, having generally a thickness that is less than 2 millimeters while
further
comprising microscopically minute pores which are small enough to permit the
passage of
gases therethrough, but not liquid molecules, e.g., and without limitation,
water molecules.
Some exemplary thin expanded plastic membranes include expanded polyurethane
films,
polytetrafluorethylene (PTFE), polypropylene and polyethylene. Other materials
may readily
present themselves to the skilled artisan, each such gas permeable, liquid
impermeable
material is within the scope of the present invention.
[0041] The present invention should not be considered limited to the
particular examples
described above, but rather should be understood to cover all aspects of the
invention.
Various modifications, equivalent processes, as well as numerous structures to
which the
present invention may be applicable will be readily apparent to those of skill
in the art to
which the present invention is directed upon review of the present
specification.
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