U.S. patent application number 16/248193 was filed with the patent office on 2019-08-15 for method and kit for treatment of tissue.
The applicant listed for this patent is Thermage, Inc.. Invention is credited to Mitchell Levinson, Roger A. Stern.
Application Number | 20190247104 16/248193 |
Document ID | / |
Family ID | 33130417 |
Filed Date | 2019-08-15 |
United States Patent
Application |
20190247104 |
Kind Code |
A1 |
Stern; Roger A. ; et
al. |
August 15, 2019 |
METHOD AND KIT FOR TREATMENT OF TISSUE
Abstract
Methods for creating a desired tissue effect. An RF electrode is
provided that includes a conductive portion. The RF electrode is
coupled to a fluid delivery member that delivers a cooling fluidic
medium to a back surface of the RF electrode. A dielectric is
positioned on a skin surface. The RF electrode is coupled with the
dielectric. RF energy is delivered from the RF electrode and the
dielectric to the skin surface.
Inventors: |
Stern; Roger A.; (Cupertino,
CA) ; Levinson; Mitchell; (Pleasanton, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Thermage, Inc. |
Hayward |
CA |
US |
|
|
Family ID: |
33130417 |
Appl. No.: |
16/248193 |
Filed: |
January 15, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15346941 |
Nov 9, 2016 |
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16248193 |
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14157088 |
Jan 16, 2014 |
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15346941 |
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11759045 |
Jun 6, 2007 |
8685017 |
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14157088 |
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10400187 |
Mar 25, 2003 |
7229436 |
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11759045 |
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10072475 |
Feb 6, 2002 |
7022121 |
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10400187 |
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10072610 |
Feb 6, 2002 |
7141049 |
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10072475 |
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09522275 |
Mar 9, 2000 |
6413255 |
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10072610 |
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09522275 |
Mar 9, 2000 |
6413255 |
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10072610 |
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10026870 |
Dec 20, 2001 |
6749624 |
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10400187 |
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60123440 |
Mar 9, 1999 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 2018/00875
20130101; A61B 2018/00702 20130101; A61N 1/06 20130101; A61F
2007/0021 20130101; A61N 1/28 20130101; A61B 18/148 20130101; A61B
90/02 20160201; A61F 7/007 20130101; A61B 2018/0066 20130101; A61B
2018/00011 20130101; A61B 18/14 20130101; A61N 1/0472 20130101;
A61B 2090/064 20160201; A61B 2017/003 20130101; A61B 18/12
20130101; A61B 2018/00452 20130101; A61H 9/0071 20130101; A61N
1/403 20130101; A61H 2201/10 20130101; A61B 2018/00714 20130101;
A61B 2018/00779 20130101; A61B 2018/00023 20130101; A61B 2018/00791
20130101; A61M 2205/3606 20130101; A61B 2018/0047 20130101; A61N
1/0468 20130101; A61B 18/00 20130101; A61N 1/32 20130101; A61B
2018/00488 20130101; A61N 2005/0645 20130101; A61B 2018/1495
20130101; A61N 1/30 20130101; A61H 9/005 20130101; A61H 7/001
20130101; A61B 18/1206 20130101; A45D 44/22 20130101; A61B 18/1402
20130101 |
International
Class: |
A61B 18/00 20060101
A61B018/00; A61B 18/12 20060101 A61B018/12; A61B 18/14 20060101
A61B018/14; A61N 1/04 20060101 A61N001/04; A61N 1/28 20060101
A61N001/28; A61N 1/30 20060101 A61N001/30; A45D 44/22 20060101
A45D044/22; A61N 1/40 20060101 A61N001/40; A61B 90/00 20060101
A61B090/00; A61F 7/00 20060101 A61F007/00; A61N 1/06 20060101
A61N001/06 |
Claims
1. A system configured to transcutaneously treat tissue with
electromagnetic energy, the system comprising: a first treatment
electrode; a generator coupled with the first treatment electrode,
the generator configured to generate the electromagnetic energy;
and a system controller coupled with the generator, the system
controller configured cause the electromagnetic energy to be
provided from the generator to the first treatment electrode with a
power profile having a plurality of differing power levels over a
treatment time divided into a plurality of time intervals each
associated with a respective one of the power levels.
2. The system of claim 1 wherein the differing power levels range
from a first power that is at least 20 percent above a nominal
power of 200 joules per second to a second power that is at least
20 percent below the nominal power of 200 joules per second.
3. An apparatus comprising: a first treatment electrode having a
surface; a tip frame composed of an electrically-insulating
material, the top frame including an opening having an inner edge
and an outer peripheral edge, the opening arranged relative to the
surface of the first treatment electrode to expose a first portion
of the first treatment electrode and to cover a second portion of
the surface of the first treatment electrode, wherein the second
portion of the surface of the first treatment electrode is located
between the outer peripheral edge of the tip frame and the inner
edge of the opening in the tip frame.
4. The system of claim 1 further comprising: a handpiece.
5. The system of claim 4 comprising: a treatment tip coupled in a
removable manner with the handpiece, wherein the treatment tip
includes the first treatment electrode.
6. The system of claim 1 further comprising a second treatment
electrode coupled with the generator, wherein the system controller
is configured cause the electromagnetic energy to be provided from
the generator to the second treatment electrode with the power
profile.
7. The apparatus of claim 3 further comprising: a second treatment
electrode.
8. The apparatus of claim 7 wherein the first treatment electrode
and the second treatment electrode are configured to be
individually energized to deliver electromagnetic energy.
9. The apparatus of claim 3 further comprising: a temperature
sensor configured to sense a temperature at the treatment
electrode.
10. The apparatus of claim 9 wherein the temperature sensor is a
thermistor or a thermocouple.
11. The apparatus of claim 3 further comprising: a pressure
sensor.
12. The apparatus of claim 3 wherein the first treatment electrode
and the tip frame are comprised of flexible materials.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of application Ser. No.
15/346,941, filed Nov. 9, 2016, which is a continuation of
application Ser. No. 14/157,088, filed Jan. 16, 2014, which is a
divisional of application Ser. No. 11/759,045, filed Jun. 6, 2007,
now U.S. Pat. No. 8,685,017, which is a divisional of application
Ser. No. 10/400,187, filed Mar. 25, 2003, now U.S. Pat. No.
7,229,436, which is a continuation-in-part of application Ser. No.
10/072,475, filed Feb. 6, 2002, now U.S. Pat. No. 7,022,121, and a
continuation-in-part of application Ser. No. 10/072,610, filed Feb.
6, 2002, now U.S. Pat. No. 7,141,049, both of which are
continuations-in-part of application Ser. No. 09/522,275, filed
Mar. 9, 2000, now U.S. Pat. No. 6,413,255, which claims the benefit
of Ser. No. 60/123,440, filed Mar. 9, 1999. Application Ser. No.
10/400,187, filed Mar. 25, 2003, now U.S. Pat. No. 7,229,436, is
also a continuation-in-part of application Ser. No. 10/026,870,
filed Dec. 20, 2001, now U.S. Pat. No. 6,749,624. The full
disclosure of each of these patent documents is hereby incorporated
by reference herein in its entirety.
FIELD OF THE INVENTION
[0002] This invention relates generally to methods and kits used to
deliver energy through a skin surface to create a desired tissue
effect, and more particularly to methods and kits to create a
desired tissue effect using an RF electrode and a dielectric.
DESCRIPTION OF RELATED ART
[0003] The human skin is composed of two elements: the epidermis
and the underlying dermis. The epidermis with the stratum corneum
serves as a biological barrier to the environment. In the basilar
layer of the epidermis, pigment-forming cells called melanocytes
are present. They are the main determinants of skin color.
[0004] The underlying dermis provides the main structural support
of the skin. It is composed mainly of an extra-cellular protein
called collagen. Collagen is produced by fibroblasts and
synthesized as a triple helix with three polypeptide chains that
are connected with heat labile and heat stable chemical bonds. When
collagen-containing tissue is heated, alterations in the physical
properties of this protein matrix occur at a characteristic
temperature. The structural transition of collagen contraction
occurs at a specific "shrinkage" temperature. The shrinkage and
remodeling of the collagen matrix with heat is the basis for the
technology. Although the technology can be deployed to effect other
changes to the skin, skin appendages (sweat glands, sebaceous
glands, hair follicles, etc.), or subcutaneous tissue
structures.
[0005] Collagen crosslinks are either intramolecular (covalent or
hydrogen bond) or intermolecular (covalent or ionic bonds). The
thermal cleavage of intramolecular hydrogen crosslinks is a scalar
process that is created by the balance between cleavage events and
relaxation events (reforming of hydrogen bonds). No external force
is required for this process to occur. As a result, intermolecular
stress is created by the thermal cleavage of intramolecular
hydrogen bonds. Essentially, the contraction of the tertiary
structure of the molecule creates the initial intermolecular vector
of contraction.
[0006] Collagen fibrils in a matrix exhibit a variety of spatial
orientations. The matrix is lengthened if the sum of all vectors
acts to lengthen the fibril. Contraction of the matrix is
facilitated if the sum of all extrinsic vectors acts to shorten the
fibril. Thermal disruption of intramolecular hydrogen bonds and
mechanical cleavage of intermolecular crosslinks is also affected
by relaxation events that restore preexisting configurations.
However, a permanent change of molecular length will occur if
crosslinks are reformed after lengthening or contraction of the
collagen fibril. The continuous application of an external
mechanical force will increase the probability of crosslinks
forming after lengthening or contraction of the fibril.
[0007] Hydrogen bond cleavage is a quantum mechanical event that
requires a threshold of energy. The amount of (intramolecular)
hydrogen bond cleavage required corresponds to the combined ionic
and covalent intermolecular bond strengths within the collagen
fibril. Until this threshold is reached, little or no change in the
quaternary structure of the collagen fibril will occur. When the
intermolecular stress is adequate, cleavage of the ionic and
covalent bonds will occur. Typically, the intermolecular cleavage
of ionic and covalent bonds will occur with a ratcheting effect
from the realignment of polar and nonpolar regions in the
lengthened or contracted fibril.
[0008] Cleavage of collagen bonds also occurs at lower temperatures
but at a lower rate. Low-level thermal cleavage is frequently
associated with relaxation phenomena in which bonds are reformed
without a net change in molecular length. An external force that
mechanically cleaves the fibril will reduce the probability of
relaxation phenomena and provides a means to lengthen or contract
the collagen matrix at lower temperatures while reducing the
potential of surface ablation.
[0009] Soft tissue remodeling is a biophysical phenomenon that
occurs at cellular and molecular levels. Molecular contraction or
partial denaturization of collagen involves the application of an
energy source, which destabilizes the longitudinal axis of the
molecule by cleaving the heat labile bonds of the triple helix. As
a result, stress is created to break the intermolecular bonds of
the matrix. This is essentially an immediate extra-cellular
process, whereas cellular contraction requires a lag period for the
migration and multiplication of fibroblasts into the wound as
provided by the wound healing sequence. In higher developed animal
species, the wound healing response to injury involves an initial
inflammatory process that subsequently leads to the deposition of
scar tissue.
[0010] The initial inflammatory response consists of the
infiltration by white blood cells or leukocytes that dispose of
cellular debris. Seventy-two hours later, proliferation of
fibroblasts at the injured site occurs. These cells differentiate
into contractile myofibroblasts, which are the source of cellular
soft tissue contraction. Following cellular contraction, collagen
is laid down as a static supporting matrix in the tightened soft
tissue structure. The deposition and subsequent remodeling of this
nascent scar matrix provides the means to alter the consistency and
geometry of soft tissue for aesthetic purposes.
[0011] In light of the preceding discussion, there are a number of
dermatological procedures that lend themselves to treatments which
deliver thermal energy to the skin and underlying tissue to cause a
contraction of collagen, and/or initiate a wound healing response.
Such procedures include skin remodeling, skinresurfacing, wrinkle
removal, and treatment of the sebaceous glands, hair follicles
adipose tissue and spider veins.
[0012] Currently available technologies that deliver thermal energy
to the skin and underlying tissue include Radio Frequency (RF),
optical (laser) and other forms of electromagnetic energy as well
as ultrasound and direct heating with a hot surface. However, these
technologies have a number of technical limitations and clinical
issues which limit the effectiveness of the treatment and/or
preclude treatment altogether.
[0013] These issues include the following: i) achieving a uniform
thermal effect across a large area of tissue, ii) controlling the
depth of the thermal effect to target selected tissue and prevent
unwanted thermal damage to both target and non-target tissue, iii)
reducing adverse tissue effects such as burns, redness blistering,
iv) replacing the practice of delivery energy/treatment in a
patchwork fashion with a more continuous delivery of treatment
(e.g. by a sliding or painting motion), v) improving access to
difficult-to-reach areas of the skin surface and vi) reducing
procedure time and number of patient visits required to complete
treatment. As will be discussed herein the current invention
provides an apparatus for solving these and other limitations.
[0014] One of the key shortcomings of currently available RF
technology for treating the skin is the edge effect phenomenon. In
general, when RF energy is being applied or delivered to tissue
through an electrode which is in contact with that tissue, the
current concentrate around the edges of the electrode, sharp edges
in particular. This effect is generally known as the edge effect.
In the case of a circular disc electrode, the effect manifests as a
higher current density around the perimeter of that circular disc
and a relatively low current density in the center. For a
square-shaped electrode there is typically a high current density
around the entire perimeter, and an even higher current density at
the corners.
[0015] Edge effects cause problems in treating the skin for several
reasons. First, they result in a non-uniform thermal effect over
the electrode surface. In various treatments of the skin, it is
important to have a uniform thermal effect over a relatively large
surface area, particularly for dermatological treatments. Large in
this case being on the order of several square millimeters or even
several square centimeters. In electrosurgical applications for
cutting tissue, there typically is a point type applicator designed
with the goal of getting a hot spot at that point for cutting or
even coagulating tissue. However, this point design is undesirable
for creating a reasonably gentle thermal effect over a large
surface area. What is needed is an electrode design to deliver
uniform thermal energy to skin and underlying tissue without hot
spots.
[0016] A uniform thermal effect is particularly important when
cooling is combined with heating in skin/tissue treatment
procedure. As is discussed below, a non-uniform thermal pattern
makes cooling of the skin difficult and hence the resulting
treatment process as well. When heating the skin with RF energy,
the tissue at the electrode surface tends to be warmest with a
decrease in temperature moving deeper into the tissue. One approach
to overcome this thermal gradient and create a thermal effect at a
set distance away from the electrode is to cool the layers of skin
that are in contact with the electrode. However, cooling of the
skin is made difficult if there is a non-uniform heating
pattern.
[0017] If the skin is sufficiently cooled such that there are no
burns at the corners of a square or rectangular electrode, or at
the perimeter of a circular disc electrode, then there will
probably be overcooling in the center and there won't be any
significant thermal effect (i.e. tissue heating) under the center
of the electrode. Contrarily, if the cooling effect is decreased to
the point where there is a good thermal effect in the center of the
electrode, then there probably will not be sufficient cooling to
protect tissue in contact with the edges of the electrode.
[0018] As a result of these limitations, in the typical application
of a standard electrode there is usually an area of non-uniform
treatment and/or burns on the skin surface. So uniformity of the
heating pattern is very important. It is particularly important in
applications treating skin where collagen-containing layers are
heated to produce a collagen contraction response for tightening of
the skin. For this and related applications, if the collagen
contraction and resulting skin tightening effect are non-uniform,
then a medically undesirable result may occur.
[0019] There is a need for improved methods and kits for treating
tissue sites. There is a further need for improved methods and kits
for treating skin tissue.
SUMMARY
[0020] Accordingly, an object of the present invention is to
provide an improved method and kit for treating tissue.
[0021] Another object of the present invention is to provide an
improved method and kit for treating skin tissue.
[0022] A further object of the present invention is to provide a
method and kit for treating skin tissue that utilizes an RF
electrode device with a separate dielectric coupled to the RF
electrode.
[0023] Yet another object of the present invention is to provide a
method and kit for treating skin tissue that utilizes an RF
electrode and separate dielectric that are capacitively coupled
when at least a portion of the dielectric is in contact with a skin
surface.
[0024] These and other objects of the present invention are
achieved in a method for creating a desired tissue effect. An RF
electrode is provided that includes a conductive portion. The RF
electrode is coupled to a fluid delivery member that delivers a
cooling fluidic medium to a back surface of the RF electrode. A
dielectric is positioned on a skin surface. The RF electrode is
coupled with the dielectric. RF energy is delivered from the RF
electrode and the dielectric to the skin surface.
[0025] In another embodiment of the present invention, a method for
creating a desired tissue effect provides an RF electrode with a
back plate and a plurality of electrical contact pads coupled to
the back plate. A dielectric is positioned on a skin surface. The
RF electrode is coupled to the dielectric. RF energy is delivered
from the RF electrode and the dielectric to the skin surface.
[0026] In another embodiment of the present invention, a kit is
provided. The kit has an RF electrode that includes a conductive
portion. The RF electrode is coupled to a fluid delivery member
that delivers a cooling fluidic medium to a back surface of the RF
electrode.
[0027] In another embodiment of the present invention, a kit is
provided. The kit includes an RF electrode with a conductive
portion and a flex circuit. A dielectric member is included in the
kit.
[0028] In another embodiment of the present invention, a kit is
provided that includes an RF electrode device. The RF electrode
device has a support structure, an RF electrode coupled to the
support structure and a first sensor coupled to the RF electrode. A
dielectric member is included in the kit.
[0029] In another embodiment of the present invention, a kit is
provided that has an RF electrode device including a support
structure, an RF electrode coupled to the support structure and a
first sensor coupled to the RF electrode and a non-volatile memory
coupled to the support structure. A dielectric member is included
in the kit.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] FIG. 1(a) is a cross-sectional view of one embodiment of the
handpiece of the present invention.
[0031] FIG. 1(b) is a cross-sectional view of another embodiment of
the RF device with a thermoelectric cooler.
[0032] FIG. 2 is an exploded view of the RF electrode assembly of
FIG. 1.
[0033] FIG. 3(a) is a close-up view of one embodiment of an RF
electrode of the present invention.
[0034] FIG. 3(b) illustrates one embodiment of an RF electrode,
that can be utilized with the present invention, with an outer edge
geometry configured to reduce an amount of capacitively coupled
area the outer edge.
[0035] FIG. 3(c) illustrates an one embodiment of an RF electrode,
that can be utilized with the present invention, that has voids
where there is little if any conductive material.
[0036] FIG. 4 is a cross-sectional view of the RF electrode
assembly from FIG. 1.
[0037] FIG. 5 is a side view of one embodiment of an RF handpiece
assembly of the present invention.
[0038] FIG. 6 is a rear view of the RF electrode assembly of FIG.
5.
DETAILED DESCRIPTION
[0039] In various embodiments, the present invention provides
methods for treating a tissue site. In one embodiment, an energy
delivery surface of an energy delivery device is coupled to a skin
surface. The coupling can be a direct, in contact, placement of the
energy delivery surface of the energy delivery on the skin surface,
or distanced relationship between the two with our without a media
to conduct energy to the skin surface from the energy delivery
surface of the energy delivery device. The skin surface is cooled
sufficiently to create a reverse thermal gradient where a
temperature of the skin surface is less than an underlying tissue.
Energy is delivered from the energy delivery device to the
underlying tissue area, resulting in a tissue effect at the skin
surface.
[0040] Referring now to FIG. 1(a), the methods of present invention
can be achieved with the use of a handpiece 10. Handpiece 10 is
coupled with a handpiece assembly 12 that includes a handpiece
housing 14 and a cooling fluidic medium valve member 16. Handpiece
housing 14 is configured to be coupled to an electrode assembly 18.
Electrode assembly 18 has a least one RF electrode 20 that is
capacitively coupled to a skin surface when at least a portion of
RF electrode 20 is in contact with the skin surface. Without
limiting the scope of the present invention, RF electrode 20 can
have a thickness in the range of 0.010 to 1.0 mm.
[0041] Handpiece 10 provides a more uniform thermal effect in
tissue at a selected depth, while preventing or minimizing thermal
damage to the skin surface and other non-target tissue. Handpiece
10 is coupled to an RF generator. RF electrode 20 can be operated
either in mono-polar or bi-polar modes. Handpiece 10 is configured
to reduce, or preferably eliminate edge effects and hot spots. The
result is an improved aesthetic result/clinical outcome with an
elimination/reduction in adverse effects and healing time.
[0042] A fluid delivery member 22 is coupled to cooling fluidic
medium valve member 16. Fluid delivery member 22 and cooling
fluidic medium valve member 16 collectively form a cooling fluidic
medium dispensing assembly. Fluid delivery member 22 is configured
to provide an atomizing delivery of a cooling fluidic medium to RF
electrode 20. The atomizing delivery is a mist or fine spray. A
phase transition, from liquid to gas, of the cooling fluidic medium
occurs when it hits the surface of RF electrode 20. The transition
from liquid to gas creates the cooling. If the transition before
the cooling fluidic medium hits RF electrode 20 the cooling of RF
electrode 20 will not be as effective.
[0043] In another embodiment, illustrated in FIG. 1(b), a
thermo-electric cooler 23 is utilized in place of cooling fluidic
medium valve member 16 and fluid delivery member 22.
[0044] In one embodiment, the cooling fluidic medium is a cryogenic
spray, commercially available from Honeywell, Morristown, N.J. A
specific example of a suitable cryogenic spray is R134A.sub.2,
available from Refron, Inc., 38-18 33.sup.rd St, Long Island City,
N.Y. 11101. The use of a cryogenic cooling fluidic medium provides
the capability to use a number of different types of algorithms for
skin treatment. For example, the cryogenic cooling fluidic medium
can be applied milliseconds before and after the delivery of RF
energy to the desired tissue. This is achieved with the use of
cooling fluidic medium valve member 16 coupled to a cryogen supply,
including but not limited to a compressed gas canister. In various
embodiments, cooling fluidic medium valve member 16 can be coupled
to a computer control system and/or manually controlled by the
physician by means of a foot switch or similar device.
[0045] Providing a spray, or atomization, of cryogenic cooling
fluidic medium is particularly suitable because of it provides an
availability to implement rapid on and off control. Cryogenic
cooling fluidic medium allows more precise temporal control of the
cooling process. This is because cooling only occurs when the
refrigerant is sprayed and is in an evaporative state, the latter
being a very fast short-lived event. Thus, cooling ceases rapidly
after the cryogenic cooling fluidic medium is stopped. The overall
effect is to confer very precise time on-off control of cryogenic
cooling fluidic medium.
[0046] Referring now to FIG. 2, fluid delivery member 22 and
thermo-electric cooler 23 can be positioned in handpiece housing 14
or electrode assembly 18. Fluid delivery member 22 is configured to
controllably deliver a cooling fluidic medium. Fluid delivery
member 22 and thermo-electric cooler 23 cool a back surface 24 of
RF electrode 20 and maintain back surface 24 at a desired
temperature. The cooling fluidic medium evaporatively cools RF
electrode 20 and maintains a substantially uniform temperature of
front surface 26 of RF electrode 20. Fluid delivery member 22
evaporatively cools back surface 24. Front surface 26 may or may
not be flexible and conformable to the skin, but it will still have
sufficient strength and/or structure to provide good thermal
coupling when pressed against the skin surface.
[0047] RF electrode 20 then conductively cools a skin surface that
is adjacent to a front surface 26 of RF electrode 20. Suitable
fluidic media include a variety of refrigerants such as R134A and
freon.
[0048] Fluid delivery member 22 is configured to controllably
deliver the cooling fluidic medium to back surface 24 at
substantially any orientation of front surface 26 relative to a
direction of gravity. A geometry and positioning of fluid delivery
member 22 is selected to provide a substantially uniform
distribution of cooling fluidic medium on back surface 24. The
delivery of the cooling fluidic medium can be by spray of droplets
or fine mist, flooding back surface 24, and the like. Cooling
occurs at the interface of the cooling fluidic medium with
atmosphere, which is where evaporation occurs. If there is a thick
layer of fluid on back surface 24 the heat removed from the treated
skin will need to pass through the thick layer of cooling fluidic
medium, increasing thermal resistance. To maximize cooling rates,
it is desirable to apply a very thin layer of cooling fluidic
medium. If RF electrode 20 is not horizontal, and if there is a
thick layer of cooling fluidic medium, or if there are large drops
of cooling fluidic medium on back surface 24, the cooling fluidic
medium can run down the surface of RF electrode 20 and pool at one
edge or corner, causing uneven cooling. Therefore, it is desirable
to apply a thin layer of cooling fluidic medium with a fine spray.
Thermo-electric cooler 23 achieves these same results but without
delivering a cooling medium. Thermo-electric cooler 23 is cold on
the side that is adjacent to or in contact with surface 24, while
its opposing side becomes warmer.
[0049] In various embodiments, RF electrode 20, as illustrated in
FIG. 3(a), has a conductive portion 28 and a dielectric portion 30.
Conductive portion 28 can be a metal including but not limited to
copper, gold, silver, aluminum and the like. Dielectric portion 30
can be made of a variety of different materials including but not
limited to polyimide, Teflon.RTM. and the like, silicon nitride,
polysilanes, polysilazanes, polyimides, Kapton and other polymers,
antenna dielectrics and other dielectric materials well known in
the art. Other dielectric materials include but are not limited to
polymers such as polyester, silicon, sapphire, diamond,
zirconium-toughened alumina (ZTA), alumina and the like. Dielectric
portion 30 can be positioned around at least a portion, or the
entirety of a periphery of conductive portion 28. In another
embodiment, RF electrode 20 is made of a composite material,
including but not limited to gold-plated copper, copper-polyimide,
silicon/silicon-nitride and the like.
[0050] Dielectric portion 30 creates an increased impedance to the
flow of electrical current through RF electrode 20. This increased
impedance causes current to travel a path straight down through
conductive portion 28 to the skin surface. Electric field edge
effects, caused by a concentration of current flowing out of the
edges of RF electrode 20, are reduced.
[0051] Dielectric portion 30 produces a more uniform impedance
through RF electrode 20 and causes a more uniform current to flow
through conductive portion 28. The resulting effect minimizes or
even eliminates, edge effects around the edges of RF electrode 20.
As shown in FIG. 3(c), RF electrode 20 can have voids 33 where
there is little or no conductive material. Creating voids 33 in the
conductive material alters the electric field. The specific
configuration of voids can be used to minimize edge effect, or
alter the depth, uniformity or shape of the electric field. Under a
portion 28' of the RF electrode 20 with solid conductive material
the electric field is deeper. Under a portion 28'' of RF electrode
20 with more voids, the electric field is shallower. By combining
different densities of conductive material, an RF electrode 20 is
provided to match the desired heating profile.
[0052] In one embodiment, conductive portion 28 adheres to
dielectric portion 30 which can be a substrate with a thickness, by
way of example and without limitation, of about 0.001''. This
embodiment is similar to a standard flex circuit board material
commercially available in the electronics industry. In this
embodiment, dielectric portion 30 is in contact with the tissue,
the skin, and conductive portion 28 is separated from the skin.
[0053] The thickness of the dielectric portion 30 can be decreased
by growing conductive portion 28 on dielectric portion 30 using a
variety of techniques, including but not limited to, sputtering,
electro deposition, chemical vapor deposition, plasma deposition
and other deposition techniques known in the art. Additionally,
these same processes can be used to deposit dielectric portion 30
onto conductive portion 28. In one embodiment dielectric portion 30
is an oxide layer which can be grown on conductive portion 28. An
oxide layer has a low thermal resistance and improves the cooling
efficiency of the skin compared with many other dielectrics such as
polymers.
[0054] In various embodiments, RF electrode 20 is configured to
inhibit the capacitive coupling to tissue along its outside edge
31. Referring to FIG. 3(b) RF electrode 20 can have an outer edge
31 with a geometry that is configured to reduce an amount of
capacitively coupled area at outer edge 31. Outer edge 31 can have
less of the conductive portion 28 material. This can be achieved by
different geometries, including but not limited to a scalloped
geometry, and the like. The total length of outer edge 31 can be
increased, with different geometries, and the total area that is
capacitively coupled to tissue is reduced. This produces a
reduction in energy generation around outer edge 31.
[0055] Alternatively, the dielectric material can be applied in a
thicker layer at the edges, reducing the electric field at the
edges. A further alternative is to configure the cooling to cool
more aggressively at the edges to compensate for any electric field
edge effect.
[0056] Fluid delivery member 22 has an inlet 32 and an outlet 34.
Outlet 34 can have a smaller cross-sectional area than a
cross-sectional area of inlet 32. In one embodiment, fluid delivery
member 22 is a nozzle 36.
[0057] Cooling fluidic medium valve member 16 can be configured to
provide a pulsed delivery of the cooling fluidic medium. Pulsing
the delivery of cooling fluidic medium is a simple way to control
the rate of cooling fluidic medium application. In one embodiment,
cooling fluidic medium valve member 16 is a solenoid valve. An
example of a suitable solenoid valve is a solenoid pinch valve
manufactured by the N-Research Corporation, West Caldwell, N.J. If
the fluid is pressurized, then opening of the valve results in
fluid flow. If the fluid is maintained at a constant pressure, then
the flow rate is constant and a simple open/close solenoid valve
can be used, the effective flow rate being determined by the pulse
duty cycle. A higher duty cycle, close to 100% increases cooling,
while a lower duty cycle, closer to 0%, reduces cooling. The duty
cycle can be achieved by turning on the valve for a short duration
of time at a set frequency. The duration of the open time can be 1
to 50 milliseconds or longer. The frequency of pulsing can be 1 to
50 Hz or faster.
[0058] Alternatively, cooling fluidic medium flow rate can be
controlled by a metering valve or controllable-rate pump such as a
peristaltic pump. One advantage of pulsing is that it is easy to
control using simple electronics and control algorithms.
[0059] Electrode assembly 18 is sufficiently sealed so that the
cooling fluidic medium does not leak from back surface 24 onto a
skin surface in contact with a front surface of RF electrode 20.
This helps provide an even energy delivery through the skin
surface. In one embodiment, electrode assembly 18, and more
specifically RF electrode 20, has a geometry that creates a
reservoir at back surface 24 to hold and gather cooling fluidic
medium that has collected at back surface 24. Back surface 24 can
be formed with "hospital corners" to create this reservoir.
Optionally, electrode assembly 18 includes a vent that permits
vaporized cooling fluidic medium to escape from electrode assembly
18.
[0060] The vent prevents pressure from building up in electrode
assembly 18. The vent can be a pressure relief valve that is vented
to the atmosphere or a vent line. When the cooling fluidic medium
comes into contact with RF electrode 20 and evaporates, the
resulting gas pressurizes the inside of electrode assembly 18. This
can cause RF electrode 20 to partially inflate and bow out from
front surface 26. The inflated RF electrode 20 can enhance the
thermal contact with the skin and also result in some degree of
conformance of RF electrode 20 to the skin surface. An electronic
controller can be provided. The electronic controller sends a
signal to open the vent when a programmed pressure has been
reached.
[0061] Various leads 40 are coupled to RF electrode 20. One or more
thermal sensors 42 are coupled to RF electrode. Suitable thermal
sensors 42 include but are not limited to thermocouples,
thermistors, infrared photo-emitters and a thermally sensitive
diode. In one embodiment, a thermal sensor 42 is positioned at each
corner of RF electrode 20. A sufficient number of thermal sensors
42 are provided in order to acquire sufficient thermal data of the
skin surface or the back surface 24 of the electrode 20. Thermal
sensors 42 are electrically isolated from RF electrode 20. In
another embodiment, at least one sensor 42 is positioned at back
surface 24 of RF electrode and detects the temperature of back
surface 24 in response to the delivery of cooling fluidic
medium.
[0062] Thermal sensors 42 measure temperature and can provide
feedback for monitoring temperature of RF electrode 20 and/or the
tissue during treatment. Thermal sensors 42 can be thermistors,
thermocouples, thermally sensitive diodes, capacitors, inductors or
other devices for measuring temperature. Preferably, thermal
sensors 42 provide electronic feedback to a microprocessor of the
RF generator coupled to RF electrode 20 in order to facilitate
control of the treatment.
[0063] Measurements from thermal sensors 42 can be used to help
control the rate of application of cooling fluidic medium. For
example, a cooling control algorithm can be used to apply cooling
fluidic medium to RF electrode 20 at a high flow rate until the
temperature fell below a target temperature, and then slow down or
stop. A PID, or proportional-integral-differential, algorithm can
be used to precisely control RF electrode 20 temperature to a
predetermined value.
[0064] Thermal sensors 42 can be positioned on back surface 24 of
RF electrode 20 away from the tissue. This configuration is
preferable for controlling the temperature of the RF electrode 20.
Alternatively, thermal sensors 42 can be positioned on front
surface 26 of RF electrode 10 in direct contact with the tissue.
This embodiment can be more suitable for monitoring tissue
temperature. Algorithms are utilized with thermal sensors 42 to
calculate a temperature profile of the treated tissue. Thermal
sensors 42 can be used to develop a temperature profile of the skin
which is then used for process control purposes to assure that the
proper amounts of heating and cooling are delivered to achieve a
desired elevated deep tissue temperature while maintaining skin
tissue layers below a threshold temperature and avoid thermal
injury.
[0065] The physician can use the measured temperature profile to
assure that he stays within the boundary of an ideal/average
profile for a given type of treatment. Thermal sensors 42 can be
used for additional purposes. When the temperature of thermal
sensors 42 is monitored it is possible to detect when RF electrode
20 is in contact with the skin surface. This can be achieved by
detecting a direct change in temperature when skin contact is made
or examining the rate of change of temperature which is affected by
contact with the skin. Similarly, if there is more than one thermal
sensor 42, the thermal sensors 42 can be used to detect whether a
portion of RF electrode 20 is lifted or out of contact with skin.
This can be important because the current density (amperes per unit
area) delivered to the skin can vary if the contact area changes.
In particular, if part of the surface of RF electrode 20 is not in
contact with the skin, the resulting current density is higher than
expected.
[0066] Referring again to FIG. 1(a), a force sensor 44 is also
coupled to electrode assembly 18. Force sensor 44 detects an amount
of force applied by electrode assembly 18, via the physician,
against an applied skin surface. Force sensor 44 zeros out gravity
effects of the weight of electrode assembly 18 in any orientation
of front surface 26 of RF electrode 20 relative to a direction of
gravity. Additionally, force sensor 44 provides an indication when
RF electrode 20 is in contact with a skin surface. Force sensor 44
also provides a signal indicating that a force applied by RF
electrode 20 to a contacted skin surface is, (i) above a minimum
threshold or (ii) below a maximum threshold.
[0067] As illustrated in FIG. 4, an activation button 46 is used in
conjunction with the force sensor. Just prior to activating RF
electrode 20, the physician holds handpiece 10 in position just off
the surface of the skin. The orientation of handpiece 10 can be any
angle relative to the direction of gravity. To arm handpiece 10,
the physician can press activation button 46 which tares force
sensor 44, by setting it to read zero. This cancels the force due
to gravity in that particular treatment orientation. This method
allows consistent force application of RF electrode 20 to the skin
surface regardless of the angle of handpiece 10 relative to the
direction of gravity.
[0068] RF electrode 20 can be a flex circuit, which can include
trace components. Additionally, thermal sensor 42 and force sensor
44 can be part of the flex circuit. Further, the flex circuit can
include a dielectric that forms a part of RF electrode 20.
[0069] Electrode assembly 18 can be moveably positioned within
handpiece housing 12. In one embodiment, electrode assembly 18 is
slideably moveable along a longitudinal axis of handpiece housing
12.
[0070] Electrode assembly 18 can be rotatably mounted in handpiece
housing 12. Additionally, RF electrode 20 can be rotatably
positioned in electrode assembly 18. Electrode assembly 18 can be
removably coupled to handpiece housing 12 as a disposable or
non-disposable RF device 52.
[0071] For purposes of this disclosure, electrode assembly 18 is
the same as RF device 52. Once movably mounted to handpiece housing
12, RF device 52 can be coupled to handpiece housing 12 via force
sensor 44. Force sensor 44 can be of the type that is capable of
measuring both compressive and tensile forces. In other
embodiments, force sensor 44 only measures compressive forces, or
only measures tensile forces.
[0072] RF device 52 can be spring-loaded with a spring 48. In one
embodiment, spring 48 biases RF electrode 20 in a direction toward
handpiece housing 12. This pre-loads force sensor 44 and keeps RF
device 52 pressed against force sensor 44. The pre-load force is
tared when activation button 46 is pressed just prior to
application of RF electrode 20 to the skin surface.
[0073] A shroud 50 is optionally coupled to handpiece 10. Shroud 50
serves to keep the user from touching RF device 52 during use which
can cause erroneous force readings.
[0074] A non-volatile memory 54 can be included with RF device 52.
Additionally, non-volatile memory can be included with handpiece
housing 12. Non-volatile memory 54 can be an EPROM and the like.
Additionally, a second non-volatile memory can be included in
handpiece housing 12 for purposes of storing handpiece 10
information such as but not limited to, handpiece model number or
version, handpiece software version, number of RF applications that
handpiece 10 has delivered, expiration date and manufacture date.
Handpiece housing 12 can also contain a microprocessor 58 for
purposes of acquiring and analyzing data from various sensors on
handpiece housing 12 or RF device 52 including but not limited to
thermal sensors 42, force sensors 44, fluid pressure gauges,
switches, buttons and the like.
[0075] Microprocessor 58 can also control components on handpiece
10 including but not limited to lights, LEDs, valves, pumps or
other electronic components. Microprocessor 58 can also communicate
data to a microprocessor of the RF generator.
[0076] Non-volatile memory 54 can store a variety of data that can
facilitate control and operation of handpiece 10 and its associated
system including but not limited to, (i) controlling the amount of
current delivered by RF electrode 20, (ii) controlling the duty
cycle of the fluid delivery member 22 and thermo-electric cooler
23, (iii) controlling the energy delivery duration time of the RF
electrode 20, (iv) controlling the temperature of RF electrode 20
relative to a target temperature, (v) providing a maximum number of
firings of RF electrode 20, (vi) providing a maximum allowed
voltage that is deliverable by RF electrode 20, (vii) providing a
history of RF electrode 20 use, (viii) providing a controllable
duty cycle to fluid delivery member 22 and thermo-electric cooler
23 for the delivery of the cooling fluidic medium to back surface
24 of RF electrode 20, (ix) providing a controllable delivery rate
of cooling fluidic medium delivered from fluid delivery member 22
to back surface 24, (x) providing a control of thermo-electric
cooler 23 and the like.
[0077] Referring now to FIGS. 5 and 6, RF device 52 includes a
support structure, including but not limited to a housing 60 that
defines the body of RF device 52. RF device 52 can include a back
plate 62 that is positioned at a proximal portion of support
structure 60. A plurality of electrical contact pads 65 can be
positioned at back plate 62. At least a portion of fluid delivery
member 22 and thermo-electric cooler 23 can extend through back
plate 62. Fluid delivery member 22 can be a channel with a proximal
end that is raised above the back surface of back plate 62.
[0078] First and second engagement members 64 can also be formed in
the body of support structure 60. Engagement members 64 provide
engagement and disengagement with handpiece housing 14. Suitable
engagement members 64 include but are not limited to snap members,
apertures to engage with snap members of substrate support 60, and
the like.
[0079] Handpiece 10 can be used to deliver thermal energy to modify
tissue including, but not limited to, collagen containing tissue,
in the epidermal, dermal and subcutaneous tissue layers, including
adipose tissue. The modification of the tissue includes modifying a
physical feature of the tissue, a structure of the tissue or a
physical property of the tissue. The modification can be achieved
by delivering sufficient energy to modify collagen containing
tissue, cause collagen shrinkage, and/or a wound healing response
including the deposition of new or nascent collagen, and the
like.
[0080] Handpiece 10 can be utilized for performing a number of
treatments of the skin and underlying tissue including but not
limited to, (i) dermal remodeling and tightening, (ii) wrinkle
reduction, (iii) elastosis reduction, (iv) scar reduction, (v)
sebaceous gland removal/deactivation and reduction of activity of
sebaceous gland, (vi) hair follicle removal, (vii) adipose tissue
remodeling/removal, (viii) spider vein removal, (ix) modify contour
irregularities of a skin surface, (x) create scar or nascent
collagen, (xi) reduction of bacteria activity of skin, (xii)
reduction of skin pore size, (xiii) unclog skin pores and the
like.
[0081] In various embodiments, handpiece 10 can be utilized in a
variety of treatment processes, including but not limited to, (i)
pre-cooling, before the delivery of energy to the tissue has begun,
(ii) an on phase or energy delivery phase in conjunction with
cooling and (iii) post cooling after the delivery of energy to
tissue has stopped.
[0082] Handpiece 10 can be used to pre-cool the surface layers of
the target tissue so that when RF electrode 20 is in contact with
the tissue, or prior to turning on the RF energy source, the
superficial layers of the target tissue are already cooled. When RF
energy source is turned on or delivery of RF to the tissue
otherwise begins, resulting in heating of the tissues, the tissue
that has been cooled is protected from thermal effects including
thermal damage. The tissue that has not been cooled will warm up to
therapeutic temperatures resulting in the desired therapeutic
effect.
[0083] Pre-cooling gives time for the thermal effects of cooling to
propagate down into the tissue. More specifically, pre-cooling
allows the achievement of a desired tissue depth thermal profile,
with a minimum desired temperature being achieved at a selectable
depth. The amount or duration of pre-cooling can be used to select
the depth of the protected zone of untreated tissue. Longer
durations of pre-cooling produce a deeper protected zone and hence
a deeper level in tissue for the start of the treatment zone. The
opposite is true for shorter periods of pre-cooling. The
temperature of front surface 26 of RF electrode 20 also affects the
temperature profile. The colder the temperature of front surface
26, the faster and deeper the cooling, and vice-versa.
[0084] Post-cooling can be important because it prevents and/or
reduces heat delivered to the deeper layers from conducting upward
and heating the more superficial layers possibly to therapeutic or
damaging temperature range even though external energy delivery to
the tissue has ceased. In order to prevent this and related thermal
phenomena, it can be desirable to maintain cooling of the treatment
surface for a period of time after application of the RF energy has
ceased. In various embodiments, varying amounts of post cooling can
be combined with real-time cooling and/or pre-cooling.
[0085] In various embodiments, handpiece 10 can be used in a varied
number of pulse on-off type cooling sequences and algorithms may be
employed. In one embodiment, the treatment algorithm provides for
pre-cooling of the tissue by starting a spray of cryogenic cooling
fluidic medium, followed by a short pulse of RF energy into the
tissue. In this embodiment, the spray of cryogenic cooling fluidic
medium continues while the RF energy is delivered, and is stopping
shortly thereafter, e.g. on the order of milliseconds. This or
another treatment sequence can be repeated again. Thus in various
embodiments, the treatment sequence can include a pulsed sequence
of cooling on, heat, cooling off, cooling on, heat, cool off, and
with cooling and heating durations on orders of tens of
milliseconds. In these embodiments, every time the surface of the
tissue of the skin is cooled, heat is removed from the skin
surface. Cryogenic cooling fluidic medium spray duration, and
intervals between sprays, can be in the tens of milliseconds
ranges, which allows surface cooling while still delivering the
desired thermal effect into the deeper target tissue.
[0086] In various embodiments, the target tissue zone for therapy,
also called therapeutic zone or thermal effect zone, can be at a
tissue depth from approximately 100 .mu.m beneath the surface of
the skin down to as deep as 10 millimeters, depending upon the type
of treatment. For treatments involving collagen contraction, it can
be desirable to cool both the epidermis and the superficial layers
of the dermis of the skin that lies beneath the epidermis, to a
cooled depth range between 100 .mu.m two millimeters. Different
treatment algorithms can incorporate different amounts of
pre-cooling, heating and post cooling phases in order to produce a
desired tissue effect at a desired depth.
[0087] Various duty cycles, on and off times, of cooling and
heating are utilized depending on the type of treatment. The
cooling and heating duty cycles can be controlled and dynamically
varied by an electronic control system known in the art.
Specifically the control system can be used to control cooling
fluidic medium valve member 16 and the RF power source.
[0088] The foregoing description of a preferred embodiment of the
invention has been presented for purposes of illustration and
description. It is not intended to be exhaustive or to limit the
invention to the precise forms disclosed. Obviously, many
modifications and variations will be apparent to practitioners
skilled in this art. It is intended that the scope of the invention
be defined by the following claims and their equivalents.
* * * * *