U.S. patent application number 11/678308 was filed with the patent office on 2007-09-20 for electrosurgical device.
This patent application is currently assigned to Smith & Nephew, Inc.. Invention is credited to Andzrej Bortkiewicz.
Application Number | 20070219406 11/678308 |
Document ID | / |
Family ID | 34700691 |
Filed Date | 2007-09-20 |
United States Patent
Application |
20070219406 |
Kind Code |
A1 |
Bortkiewicz; Andzrej |
September 20, 2007 |
ELECTROSURGICAL DEVICE
Abstract
An electrosurgical device includes a high dielectric material
and at least one conductor arranged relative to the high dielectric
material such that, in use, the high dielectric material is
disposed between the conductor and target tissue. A second
conductor is arranged relative to the high dielectric material such
that, in use, the high dielectric material is disposed between the
second conductor and target tissue. Each conductor includes a
plurality of conductive fingers interleaved, e.g. in a comb-like
fashion or as concentric circles. A method for performing
electrosurgery includes delivering energy to a target tissue
through a high dielectric material. The electrosurgery includes,
e.g., ablation, coagulation, or the treatment of skin lesions.
Inventors: |
Bortkiewicz; Andzrej; (South
Hamilton, MA) |
Correspondence
Address: |
FISH & RICHARDSON P.C.;SMITH & NEPHEW, INC.
150 Minuteman Road
Andover
MA
01810
US
|
Assignee: |
Smith & Nephew, Inc.
Memphis
TN
|
Family ID: |
34700691 |
Appl. No.: |
11/678308 |
Filed: |
February 23, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10747101 |
Dec 30, 2003 |
7182762 |
|
|
11678308 |
Feb 23, 2007 |
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Current U.S.
Class: |
600/37 |
Current CPC
Class: |
A61B 18/148 20130101;
A61B 2018/00083 20130101 |
Class at
Publication: |
600/037 |
International
Class: |
A61B 18/18 20060101
A61B018/18 |
Claims
1. An electrosurgical device comprising: a high dielectric
material; means for delivering energy to a target tissue through
the high dielectric material; and means for adjusting a penetration
depth of the delivered energy.
2. An electrosurgical device comprising: means for providing
electrical energy; means for distributing the electrical energy so
as to obtain a substantially uniform field distribution, wherein,
in use, the substantially uniform field distribution is applied to
a target tissue; and means for adjusting a penetration depth of the
electrical energy.
3. An electrosurgical device comprising: means for providing
electrical energy; means for applying the electrical energy to a
target tissue such that electric current does not flow through
tissue immediately adjacent to the target tissue; and means for
adjusting a penetration depth of the applied electrical energy.
Description
CLAIM OF PRIORITY
[0001] This application is a continuation of U.S. patent
application Ser. No. 10/747,101, filed on Dec. 30, 2003, the entire
contents of which are hereby incorporated by reference.
TECHNICAL FIELD
[0002] This description is related to surgical devices and methods
for applying thermal and/or electrical energy to organic material
such as biological tissue to modify characteristics of the tissue
for therapeutic purposes. More particularly, the description is
related to electrosurgical devices using radio frequency (RF)
energy to cut, coagulate, ablate, or otherwise treat tissue during
a medical procedure.
BACKGROUND
[0003] Surgical instruments employing RF energy for treatment are
used in a variety of surgical procedures. Such instruments
generally include an RF probe that delivers RF energy to the part
of the body to be affected by the electrosurgical procedure.
[0004] Present RF probes are typically either mono-polar or
bi-polar probes. Mono-polar probes have a single RF electrode. The
RF energy of the mono-polar probe passes from the RF electrode
through the area to be treated and then returns through a return
electrode attached to the body, often a foot or more away. Bipolar
probes include two terminals, an active electrode and a return
electrode, which are both positioned within the patient at the area
to be treated.
SUMMARY
[0005] In one aspect, an electrosurgical device includes a high
dielectric material and at least one conductor arranged relative to
the high dielectric material such that, in use, the high dielectric
material is disposed between the conductor and target tissue.
[0006] Implementations of this aspect may include one or more of
the following features. A second conductor is arranged relative to
the high dielectric material such that, in use, the high dielectric
material is disposed between the second conductor and target
tissue. Each conductor includes a plurality of conductive fingers.
The first plurality of fingers is interleaved, e.g. in a comb-like
fashion, with the second plurality of fingers. The device includes
a RF power generator and a network coupling the first and second
plurality of fingers to the RF power generator.
[0007] In an illustrated embodiment, a switching network coupling
the RF generator to the conductive fingers controls the depth of
treatment of the tissue. The switching network has a first state in
which an RF electrical field extends to a first length from a
tissue treatment surface of the high dielectric material and a
second state in which the RF electrical field extends to a second
length from the tissue treatment surface, which is longer than the
first length.
[0008] In another embodiment, each of the conductors includes a set
of concentric circles, and the concentric circles are
interleaved.
[0009] The RF power generator connected to the conductor is
configured to provide RF power with a voltage and a frequency
sufficient to produce a dielectric barrier discharge plasma at the
surface of the high dielectric material. The RF generator is
configured to provide RF power at a frequency up to about 20 MHz
and a voltage up to about 1500 Vrms. The RF generator is configured
to provide RF power with a voltage and a frequency sufficient to
result in a current density at a surface of the high dielectric
material that is greater than about 0.2 amperes per millimeter
squared and that can be as high as about 1.0 ampere per millimeter
squared.
[0010] The high dielectric material includes a ceramic material.
The high dielectric material is a material having a dielectric
constant greater than approximately 10, e.g., typically between
about 100 and 1000.
[0011] In another aspect, a method for performing electrosurgery
includes delivering energy to a target tissue through a high
dielectric material.
[0012] Implementations of this aspect may include one or more of
the following features.
[0013] The electrosurgery includes ablating or coagulating the
target tissue or treating lesions. Delivering the energy includes
forming a dielectric barrier discharge plasma; high density RF
currents (for thermal treatment); or a high strength RF electrical
field (for voltage treatment) at the surface of the high dielectric
material. Energy is delivered with a frequency up to about 20 MHz
and a RF power density up to about 50 W per millimeter squared.
[0014] The target tissue is in either a non-conductive or
conductive environment. The target tissue can be a variety of
biological tissues such as, e.g., cartilage, muscle, fat, or
ligament.
[0015] In another aspect, an electrosurgical device includes a high
dielectric material and at least one conductor arranged relative to
the high dielectric material such that, in use, energy is delivered
to a target tissue through the high dielectric material.
[0016] In another aspect, RF energy is applied to a target tissue
with a conductor without galvanic contact between the conductor and
the target tissue or between the conductor and a conductive medium
surrounding the target tissue.
[0017] In another aspect, an electrosurgical device includes means
for providing electrical energy and means for distributing the
electrical energy so as to obtain a substantially uniform field
distribution, wherein, in use, the substantially uniform field
distribution is applied to a target tissue.
[0018] In another aspect, an electrosurgical device includes means
for providing electrical energy and means for applying the
electrical energy to a target tissue such that electric current
does not flow through tissue immediately adjacent to the target
tissue.
[0019] Advantages may include one or more of the following. For
example, the present device and method eliminates or reduces the RF
return current and high electrical field present in the tissue
surrounding the targeted tissue, thereby reducing or eliminating
collateral damage. The configuration of the device provides for a
stable discharge region that can be ignited regardless of the
device's proximity to tissue and with properties that are not
dependent on the device's proximity to tissue. The RF energy is
distributed evenly due to impedance of the ceramic. The RF energy
is concentrated in a very thin layer at the surface of the ceramic.
There is no return path of RF current in the tissue. The ceramic
prevents concentration of the RF energy in a small region of the
treated area.
[0020] The apparatus and method are applicable in a wide variety of
medical procedures on a wide range of different bodily tissues. The
apparatus can be used in electrosurgery in a saline environment or
in glycine or air and can be used, e.g., to treat chondromalacia
and for surgery on anterior cruciate ligaments.
[0021] The details of one or more implementations are set forth in
the accompanying drawings and the description below. Other
features, objects, and advantages will be apparent from the
description and drawings, and from the claims.
DESCRIPTION OF DRAWINGS
[0022] FIG. 1 is a side view of an electrosurgical device.
[0023] FIG. 2A is a perspective view of a distal portion of the
electrosurgical device.
[0024] FIG. 2B is a cross-sectional view of the distal portion of
the device taken along the line 2B-2B' in FIG. 2A.
[0025] FIG. 2C is a plan view of the distal portion of the
device.
[0026] FIG. 2D is a plan view showing the assembly of a disc
included as part of the distal portion of the device.
[0027] FIG. 3 is a schematic diagram showing the connection of
electrical energy to the electrosurgical device.
[0028] FIGS. 4A and 4B are simulations of the electric field and
current density, respectively, at a surface of the distal portion
of the device.
[0029] FIGS. 4C and 4D are simulations showing the electric field
for alternate configurations of the distal portion.
[0030] FIG. 5 is a side view showing a use of the electrosurgical
device.
[0031] FIG. 6 is a schematic diagram showing a switching network
for use with the electrosurgical device.
[0032] FIGS. 7 and 8 are plan views showing alternate configuration
for the distal portion.
DETAILED DESCRIPTION
[0033] Referring to FIG. 1, an electrosurgical device 100 includes
a handle 105 connected to an elongated shaft 110 and a power cable
120. Power cable 120 includes a power connector 125 for connection
to a source of electrical energy such as an RF power generator (not
shown). Shaft 110 is hollow and formed from, e.g., an insulative
plastic such as Teflon, polyethylene, polystyrene, or other
thermally molded plastic, or made from a metal tube.
[0034] Shaft 110 has a distal portion 115 that includes an
insulated region 205 terminating at a disc 210. Disc 210 is, e.g.,
approximately 5 mm in diameter and has an overall thickness of
between 25 and 60 mils. Disc 210 has a tissue treatment surface 225
and is formed of a high dielectric material, that is, a material
having a dielectric constant greater than about 10, preferably
between 100 and 1000.
[0035] Referring to FIGS. 2A-2C, embedded within disc 210 is an RF
antenna 200. The RF antenna 200 is constructed from a first
plurality of conductive fingers 215a interleaved in a comb-like
fashion with a second plurality of conductive fingers 215b such
that each one of fingers 215a is adjacent to one of fingers 215b.
Fingers 215a and 215b are embedded in disc 210 and are shown in
FIG. 2A as dashed lines. However, FIG. 2C illustrates fingers 215a
and 215b as solid lines for clarity. Adjacent fingers are equally
separated by a distance d, as discussed further below.
[0036] The material of disc 210 preferably also has high electrical
isolation to limit voltage breakdown between adjacent conductors.
This material is preferably resistant to high temperature and the
aggressive chemical environment of RF plasmas. Ceramic is an
example of a material that is a high dielectric and has good
electrical isolation. Some examples of ceramics suitable for use
are those made by American Technical Ceramics, One Norden Lane,
Huntington Station, N.Y. 11746 with the dielectric designations of
CC, EA, or GA.
[0037] As shown in FIG. 2A, fingers 215a are connected to a first
lead 220a that connects fingers 215a to a first terminal of the RF
power generator through power cable 120 and connector 125.
Similarly, fingers 215b are connected to a second lead 220b that
connects conductors 215b to a second terminal of the RF power
generator through power cable 120 and connector 125. Accordingly,
fingers 215a receive one polarity of the RF voltage, while fingers
215b receive the opposite polarity. Leads 220a and 220b pass
through the hollow portion of shaft 110 to power cable 120.
[0038] Referring to FIG. 2D, disc 210 is, e.g., formed from a first
section of dielectric material 210a and a second section of
dielectric material 210b. First section 210a has a thickness of,
e.g., between 5 to 10 mils and second section 210b has a thickness
of, e.g., between 20 to 50 mils. Sections 210a and 210b can have
the same or different dielectric constants.
[0039] First section 210a has tissue treatment surface 225 and a
second surface 235 opposite from tissue treatment surface 225.
Disposed on second surface 235 are conductive fingers 215a and
215b. Fingers 215a and 215b are disposed on surface 235 using, for
example, standard metal deposition and etching techniques.
[0040] Second section 210b of dielectric material 210b has a
surface 245 with trenches or voids designed to receive conductive
fingers 215a and 215b such that fingers 215a and 215b are
encapsulated. A bonding technique is used to join surfaces 235 and
245 and to join fingers 215a and 215b to trenches 240 to form a
single disc 210 with fingers 215a and 215b embedded therein. Second
section 210b provides mechanical strength to disc 210 and
electrical isolation between conductive fingers 215a and 215b.
Second section 210b can also act to distribute heat from the
surface 225.
[0041] Referring to FIG. 3, fingers 215a are connected to a first
terminal 315 of an RF power generator 305 through lead 220a.
Similarly, fingers 215b are connected to a second terminal 310 of
RF power generator 305 through second lead 220b.
[0042] When connected to RF power generator 305, fingers 215a and
215b radiate RF energy as shown by dashed lines 320, which
represent the equipotential lines of the electric field, and solid
lines 325, which represent the RF vectors of the electric field.
The capacitive impedance of disc 210 distributes the RF energy
essentially evenly over surface 225. This electrical impedance is a
major component in the RF electrical circuit formed by RF power
generator 305, leads 220a and 220b, disc 210 and conductors 215a
and 215b. Thus, the surface of disc 210 acts as an RF energy
distributing component. As a result, the RF energy density is
substantially uniformly spread over surface 225 and is not affected
to any significant degree by uneven proximity to the surrounding
tissue.
[0043] The RF energy is primarily confined to the area in front of
surface 225. Consequently, when surface 225 is applied to or near
the tissue to be treated, the RF energy is applied primarily to the
tissue to be treated, which can, e.g., reduce or eliminate
collateral damage.
[0044] Different delivery rates of RF energy can be used for
various treatments. For example, as described further below, a high
RF energy density can be used to ignite a plasma discharge for use
in ablating or cutting tissue. In a procedure such as coagulation,
on the other hand, the RF energy density is kept low enough to
prevent the ignition of a plasma discharge. Coagulation is
performed using thermal treatment with a RF current density of up
to, for example, about 0.8 A/mm squared. Similarly, an electric
field with a low power density can be used to kill cells in a
treatment area. This is achieved, e.g., by connecting the probe to
a low frequency or a pulsing high frequency, voltage source, such
as, a high density pulsed electric field, e.g., a pulsing electric
field with a duration of about 1 us to 100 us, a repetition rate
from about 10 kHz to 1 Hz, and a voltage field of up to about 200
V/mil (which is equal to 7.9 kV/mm).
[0045] Referring to FIGS. 4A and 4B, a simulation, using finite
element analysis software, was conducted to demonstrate that the
electric field is located primarily at the treatment surface of the
dielectric material. For the simulation, copper with an electrical
conductivity of 5.8e+07 Siemens per meter was used for fingers 415a
and 415b and ceramic with a dielectric constant of 650 was used for
high dielectric material 410. The simulation was a two dimensional
simulation, with the height of the ceramic material 210 being 0.065
inches and the width being 0.36 inches. The spacing from surface
425 to conductors 415a and 415b was 0.005 inches. The thickness of
conductors 415a and 415b was 0.005 inches and the width of
conductors 415a and 415b was 0.0175 inches. The spacing between
conductors 415a and 415b was 0.015 inches. The simulation was
conducted for a saline environment, using salt water with a
dielectric constant of 81 and electrical conductivity of 4 Siemens
per meter as the surrounding medium. An RF power source with a
voltage magnitude of .+-.150 V and a frequency of 13 MHz was
applied to conductors 415a and 415b, with conductors 415a receiving
one polarity and conductors 415b receiving the opposite polarity.
As can be seen, electric field 400 and current density 405 radiated
outward from surface 425 to a distance of approximately 10 mils and
was confined primarily to the area in front of surface 425.
[0046] In the simulation, the two end fingers were spaced farther
apart from their respective adjacent fingers in an attempt to make
the distribution of the electric field and current density more
uniform. Because of the boundary conditions at the edges of
material 410, for equally spaced fingers 415a and 415b, the
distribution of the electric field and current density will be
different at the edges of the material than in the central portion.
By adjusting the spacing between the fingers at each edge, a more
uniform distribution of the RF current and electric field across
surface 425 can be achieved.
[0047] Unequal spacing can also be used between adjacent conductors
so that the RF electric field radiates or extends outward to
different distances in different areas of surface 425 or, in other
words, an RF field is produced that has different penetration
depths in different areas of surface 425. As described, when RF
power is applied to fingers 415a and 415b, a high concentration of
the RF electric field is created at surface 425. The thickness of
this field is a function of the distance d between adjacent fingers
of opposite polarity. The further apart conductors of opposite
polarity are, the further the electric field extends from surface
425. Thus, the spacing of the conductors can be optimized for
specific applications.
[0048] Referring to FIG. 4C, a simulation was conducted to
demonstrate that different penetration depths of the electric field
can be achieved with different spacings between adjacent fingers.
The width and thickness of the conductors was 7.5 mils and 5 mils,
respectively. A first set 430a of fingers 415a and 415b are spaced
7.5 mils apart, while a second set 430b of fingers 415a and 415b
are spaced 30 mils apart. The other parameters are the same as
those for FIGS. 4A and 4B. As can be seen, the electric field 435
has a first area 440a above the first set 430a of fingers 415a and
415b that extends out from surface 425 a smaller distance than a
second area 440b of the electric field 435 above the second set
430b of fingers 415a and 415b. The first area 440a extends
approximately 10 mils, while the second area 440b extends
approximately 40 mils.
[0049] Referring to FIG. 4D, another simulation was performed to
demonstrate that the shape of fingers 415a and 415b affects the
penetration depth in addition to the spacing between fingers 415a
and 415b. The parameters are the same as those for FIG. 4C, except
that the width and thickness of the second set 430b of fingers 415a
and 415b are 17.5 mils and 5 mils, respectively. As shown,
increasing the width of the second set of fingers 430b resulted in
the second area 440b of the electric field 435 extending further
from surface 425 than first area 440a.
[0050] A dielectric barrier discharge (DBD) plasma can be ignited
at surface 225 when RF energy is applied to conductors 215a and
215b. This discharge is particularly applicable when the goal is to
cut or ablate tissue. The plasma exists primarily in a thin layer
over surface 225. As a result, collateral damage due to the plasma
is reduced or eliminated.
[0051] The current density needed to ignite the discharge plasma is
obtained by adjusting the voltage or frequency of the RF power
applied for a given thickness and dielectric constant of disc 210.
For example, assuming a current density of 0.2 A/mm.sup.2 is needed
to ignite a discharge, then a voltage and frequency of the RF power
applied to conductors 215a and 215b equal to 570 V and 5 MHz,
respectively, can be used for a thickness of disc 210 equal to
0.125 mm and a dielectric constant of disc 210 equal to 200.
[0052] To arrive at this, the following relationship is used: V RF
.apprxeq. I RF .omega. .times. .times. C cer = J A .omega. .times.
.times. C cer ##EQU1## where V.sub.RF is the RF voltage, I.sub.RF
is the RF current, which is equal to the current density J times
the area A of the high dielectric material through which the
current passes, .omega. is the angular frequency of the RF power,
and C.sub.cer is the capacitance of the high dielectric
material.
[0053] The capacitance in picofarads is equal to: C cer = 8.5 10 -
3 A d ##EQU2## where .di-elect cons. is the dielectric constant of
material 210 and d is the thickness of material 210 in millimeters,
and A is surface area of material 210 in millimeters squared. Thus,
the RF voltage V.sub.RF becomes: V RF .apprxeq. J d 8.5 10 - 3
.omega. ##EQU3## For a current density of 0.2 A/mm.sup.2, a
dielectric constant of 200, and a thickness of 0.125 mm (which is
equivalent to 5 mils): V RF .apprxeq. 1.47 10 10 .omega. . ##EQU4##
Choosing a frequency f=5 MHz results in a voltage V.sub.RF=570V.
The frequency or voltage is preferably chosen in view of other
parameters such as the dielectric breakdown of disc 210. For
example, if disc 210 has a dielectric strength of 150 V/mils, then
for a thickness of 5 mils the dielectric material has a breakdown
voltage of 750 V. Accordingly, the above parameters could be used
without exceeded the breakdown voltage of disc 210.
[0054] The particular parameters required to ignite the plasma in a
given environment can be determined as a matter of routine
experimentation. The frequency of the RF energy can be up to
approximately 20 MHz. Theoretically, frequencies higher than 20 MHz
can be used, but in practice such high frequencies are difficult to
generate and can cause problems such as interference with other
electrical devices. Generally, plasma ignition in saline is
achieved with approximately a quarter of the RF field strength
required for ignition in air.
[0055] Referring to FIG. 5, in use to treat body tissue 505, such
as, for example, articular cartilage, surface 225 is placed in
contact with a tissue treatment site 510 or near enough to the
tissue treatment site 510 that the electric field or plasma
discharge region affects the treatment site 510. As a surgeon
applies energy to fingers 215a and 215b, RF energy is radiated
outward and distributed along surface 225, in a pattern similar to
that shown in FIGS. 4A and 4B. In a treatment including, for
example, ablation of tissue at tissue treatment site 510, the RF
power applied to conductors 215a and 215b is such that a DBD plasma
515 is formed at surface 225. To ablate an area of tissue, distal
portion 115 along with plasma 515 is moved along the desired
ablation area of tissue.
[0056] Other surgical procedures (e.g., coagulation or treatment of
skin lesions) is performed without forming a DBD plasma. Rather,
the RF electric field distributed across and extending from surface
225, and/or any thermal energy resulting from the electric field,
are used to treat the tissue. The heat is dissipated in the treated
tissue limiting any collateral damage to the surrounding
tissue.
[0057] Thus, during use, RF energy is applied to a target tissue
with a conductor such that the RF energy is applied without
galvanic contact (i.e., without direct electric contact) between
the conductor and the target tissue or between the conductor and a
conductive medium surrounding the target tissue. In the
implementations shown, the RF energy is applied through the
dielectric material without the conductors and being in direct
electric contact with the tissue and without the conductors being
in direct electrical contact with a conductive medium (e.g.,
saline) surrounding the tissue.
[0058] Referring to FIG. 6, for some electrosurgical procedures it
is desirable to have the ability to adjust the penetration depth of
the RF field. As described above, different spacings between
adjacent fingers provide for different penetration depths of the RF
field. A switching network 650 is one example of how to adjust the
RF electric field's depth of penetration. RF generator 605, disc
610, and fingers 651a and 615b are the same as described in FIGS.
1-3 and fingers 615a and 615b are spaced from one another by a
distance d.sub.1. Fingers 615a and 615b are connected to RF
generator 605 through switching network 650 and three leads 620a,
620b, and 620c. Switching network 650 has two switches, switch 630
and switch 635. When first and second switches 630 and 635 are in a
high state (not shown), all of fingers 615a are connected to first
terminal 640 of RF generator through both leads 620a and 620b,
while all of fingers 615b are connected to second terminal 645
through lead 620c. In this configuration, the distance between
adjacent conductors of opposite polarity is d.sub.1 and an electric
field extends a first length from surface 625 of high dielectric
material 610.
[0059] When first and second switches 630 and 635 are in a low
state (as shown), every other one of fingers 615a are connected to
second terminal 645 of RF generator 605 through lead 620b, while
the other fingers 615a are connected to first terminal 640.
Conductors 615b are not connected to either terminal of RF
generator 605. In this configuration, the distance between adjacent
conductors of opposite polarity is d.sub.2, which is greater than
distance d1. As a result, the electric field extends a second
length from surface 625, which is farther than the first
length.
[0060] A number of implementations have been described.
Nevertheless, it will be understood that various modifications may
be made. For example, other configurations of electrosurgical
device 100 have the insulative material of portion 205 covering the
side 230 (FIG. 2A) of section 210, while leaving surface 225
exposed. Also, shaft 110 can be made from other materials and with
different configurations. For instance, distal portion 115 can have
a ninety degree bend such that surface 225 is side-facing. Other
bend degrees are also possible such as, for example, sixty degrees,
forty-five degrees, or thirty degrees, or the shaft can be flexible
with an adjustable angle.
[0061] Other dimensions and shapes of disc 210 can be used,
depending on the application and the surface area of treatment.
Also, while it may be desirable to use a material for disc 210 with
high electrical isolation, the material can have some conductivity.
For example, a semiconductor material can be used.
[0062] Other configurations of disc 210 can also be used. For
example, disc 210 has varying dielectric constants along a length
and/or diameter. Referring to FIG. 7, for example, conductors 715a
and 715b are embedded in disc 710. Disc 710 has three distinct
sections, 720, 725, and 730. Each section 720, 725, and 730 is made
from a material with a different dielectric constant. Rather than
discrete sections, other configurations have gradually varying
dielectric constants across a length or diameter.
[0063] Further, the second section of dielectric material 210b can
be eliminated and other techniques used to insure electrical
isolation between conductive fingers 215a and 215b. For example, a
coating of glass or other insulating material is applied to surface
235 and conductors 215a and 215b to provide electrical isolation
between conductors 215a and 215b. Alternatively, distal portion 115
is configured such that a vacuum exists at the surface 235 of
dielectric 210a to provide electrical isolation between conductors
215a and 215b.
[0064] Other configurations of the embedded conductors can also be
used. Referring to FIG. 8, for example, conductors 715a and 715b
are interleaved as concentric circles. Fingers 715a are connected
to one terminal of the RF power generator, while fingers 715b are
connected to the other terminal.
[0065] Moreover, electrosurgical device 100 can have other
configurations. For example, electrosurgical device 100 is provided
with an internal RF generator, and power cable 120 and connector
125 connect the internal RF generator to AC or DC power.
Alternatively, in addition to an internal RF generator,
electrosurgical device includes an internal battery to power the RF
generator. In this case, power cable 120 and connector 125 are
eliminated.
[0066] The electrosurgical device can be implemented as a
self-coagulating surgical blade. When implemented in this manner,
dielectric material 210b is deposited at the surface of a surgical
blade for instant coagulation of, e.g., small arteries.
[0067] While an electrosurgical device has been described as
dimensioned for endoscopic or arthroscopic surgeries, other
implementations are dimensioned larger or smaller, depending on the
particular application intended. In such applications, the
thickness and size of the high dielectric material 210a is adjusted
accordingly
[0068] Accordingly, other implementations are within the scope of
the following claims.
* * * * *