Note: Descriptions are shown in the official language in which they were submitted.
CA 02820982 2013-06-28
BIPOLAR FORCEPS WITH FORCE MEASUREMENT
This invention relates to a bipolar forceps construction for use in
dissecting or electro-cauterization of tissue in surgical procedures.
BACKGROUND OF THE INVENTION
The arrangement described herein focuses on human interaction with
technology within the field of medicine. The arrangement described herein
provides
a force-sensing dissecting bipolar forceps tool. The application and
translation areas
for this tool include conventional and robotic surgery, surgical training, and
surgical
simulation. A dissecting bipolar forceps is an electro-cauterization forceps
used
worldwide in operating rooms and utilizes high-frequency electric current
between
tool tips to dissect through tissue planes or seal blood vessels. A dissecting
bipolar
forceps with the ability to also measure the forces of dissection has not been
made
available to the neurosurgical community to date.
The bipolar forceps is one of the primary tools used in neurosurgery.
There are more than 2400 hospitals in the USA and Canada equipped with
neurosurgical operating rooms. There are multiple neurosurgeries per day in
each of
these hospitals. Neurosurgeons typically have multiple bipolar forceps of
varying
length and shape on hand for use during each surgical case. Therefore, in
neurosurgery alone, there is a strong demand for bipolar forceps tools.
Furthermore,
considering disposable bipolar forceps increases the demand drastically. It
should
also be noted that bipolar forceps are used in other surgical disciplines as
well.
In general such tools comprise a pair of prongs each having a prong tip
CA 02820982 2013-06-28
2
where the prongs are connected for relative movement of the prongs for
movement
of the tips into a tip contacting position and each of the prongs has a
manually
engageable portion spaced from the tip for manual movement of the prongs to
the
tip contacting position by manual pressure on the manually engageable portion.
An
electrical supply system connected to an end of the prongs remote from the tip
is
provided for applying a high-frequency electric current between tool tips to
dissect
through tissue planes and/or seal blood vessels.
SUMMARY OF THE INVENTION
According to one aspect of the invention there is provided a bipolar
forceps tool comprising:
a pair of prongs each having a prong tip;
the prongs being connected for relative movement of the prongs for
movement of the tips into a tip contacting position;
each of the prongs having a manually engageable portion spaced from
the tip for manual movement of the prongs to the tip contacting position by
manual
pressure on the manually engageable portion;
an electrical supply system for applying a high-frequency electric
current between tool tips to dissect through tissue planes and/or seal blood
vessels;
and at least one force sensing component for measuring forces applied
to the prongs at the tip.
The force sensing component can be arranged for measuring forces
CA 02820982 2013-06-28
3
applied to the prongs by contact pressure between the tips at the tip
contacting
position, for measuring forces applied to the prongs laterally of the tip by
pulling the
tip transversely of the prongs and/or by pulling the tip longitudinally of the
prongs.
Preferably both of the prongs have force sensing components thereon
where the forces in both prongs are detected in a composite or independent
manner.
Preferably there is provided a temperature sensing component on at
least one of the prongs for measuring temperatures of tissue dissection and
coagulation in surgical procedures.
Preferably the force sensing and temperature sensing components are
protected by a protective coating/covering on the prongs in such a way as to
support
standard medical sterilization procedures on the forceps.
Preferably the means for measuring includes for each prong four
sensing components, the outputs of which are connected in a full-bridge
electrical
circuit configuration.
Preferably there is provided for the force sensing components an
arrangement for compensating for temperature fluctuations during force
measurement. This can be an arrangement for temperature compensation
comprises a temperature reference force sensing component located at a
position
so as to be at a common temperature with the force sensing component and
arranged so as to be non-responsive to the forces so as to provide a
temperature
compensation signal where for example the temperature reference force sensing
component is mounted perpendicularly to the force sensing component.
CA 02820982 2013-06-28
4
Preferably there is provided a display for displaying the forces and
temperatures of tissue dissection and coagulation in surgical procedures
present in
both prongs of the bipolar forceps in a composite or independent manner.
Preferably the display includes embedded electronic displays, smart
phones, tablets, computers, or augmented/virtual reality eye-glasses.
Preferably there is provided a force warning system that indicates to
the user when force thresholds are being exceeded via visual, audio and haptic
means.
Preferably there is provided a temperature warning system that
indicates to the user when temperature thresholds are being exceeded via
visual,
audio and haptic means.
Preferably there is provided an irrigation system for supplying irrigating
fluid to the tips, where an amount of irrigation is delivered when a
temperature
threshold is exceeded.
Preferably there is provided a computer control system which operates
for translating accurate forces of dissection, based on force recordings from
real
surgeries, into simulation software creates a training platform for novice
surgeons
with increased realism for tool-tissue interaction.
Preferably there is provided as part of the system haptic force-
generating forceps for operation in the training platform.
CA 02820982 2013-06-28
Preferably there is provided a computer control system which operates
for collecting data from clinical studies to be made available for
incorporation into
surgical simulation software.
Preferably there is provided a force calibration device customized for
5 surgical forceps to allow strain sensor voltages to be mapped to actual
forceps-tip
forces.
Preferably there is provided a computer control system which operates
to collect data at precise timing to reflect the changes in forces while the
tool is being
used on different tissue types.
The arrangement described herein provides addition of force sensors
to bipolar forceps which allows the quantification of dissection forces during
neurosurgery.
The arrangement described herein can provide one or more of the
following features:
-- force and temperature warning and data recording in a bipolar
forceps dissection and cauterization tool, while preserving standard
functionality and
allowing tool sterilization.
--is the first "smart/intelligent" bipolar forceps tool;
--includes force and temperature warning systems, as well as a
temperature-triggered self-irrigation feature.
CA 02820982 2013-06-28
6
--Also integrates display technologies and different warning modalities
(e.g. haptics, audio, visual).
Thus, the arrangement described herein incorporates force sensors
into the dissecting bipolar forceps in order to measure and record accurate
forces of
tissue dissection. The arrangement described herein advances the safety and
performance of conventional surgery, and incorporating the arrangement
described
herein into robotics increases surgeons' confidence in the tools used to
perform
robot-assisted surgeries. Furthermore, translating accurate forces of
dissection,
based on force recordings from real surgeries, into simulation software
creates a
training platform for novice surgeons with increased realism for tool-tissue
interaction.
The following problems are required to be considered:
--the mounting of the force sensors is necessary without interfering
with the standard functionality of the bipolar forceps tool.
It is required to cover the sensors and wires and to coat the tool prongs
to allow for tool sterilization.
It is necessary to provide the optimal number of force sensors and their
optimal configuration (mechanically and electrically). Typically the
arrangement
described herein uses four force sensors per prong. This is because a full-
bridge
electrical configuration is used for the sensor interconnections, since it is
one of the
more sensitive configurations and also exhibits a linear response (while other
configurations do not). Both half-bridge and full-bridge configurations grant
greater
CA 02820982 2013-06-28
7
sensitivity over the quarter-bridge circuit, but often it is not possible to
bond
complementary pairs of sensors to the test specimen.
The arrangement described herein creates a digital interface with a
high-force warning safety system for bipolar forceps where none previously
existed.
Building additional safety features into surgical procedures is highly
desirable for
both surgeons and patients. This significantly augments a surgeon's ability to
assess
force exertion during delicate surgical procedures. The arrangement described
herein produces an innovative tool that has implications for surgical safety,
performance, and training. There is an increasing demand for this type of
digital
surgical interface, particularly as surgical education requires effective
solutions to
resource-intensive training. Furthermore, the pairing of a force-sensing
forceps
(equipped with force recording capabilities) with a haptic force-generating
forceps
already developed to mirror surgeon's tool forces to a trainee is a unique
training
approach. This additional sensory feedback allows surgical trainees to
experience
the actual tool-tissue interaction forces and tool movements of an experienced
surgeon, while watching and listening to an operation. This results in a
surgical
education environment that incorporates haptic (touch) feedback in addition to
traditional visual and audio sensory modalities.
The arrangement described herein provides a microsurgical force-
sensing bipolar forceps tool for measuring the forces of dissection in
neurosurgery.
The arrangement described herein is equipped with a force warning safety
system
(e.g. with visual, audio, and haptic alerts). The arrangement described
herein,
CA 02820982 2013-06-28
8
customized specifically for the requirements of neurosurgery, allows tool-
tissue
interaction forces to be studied and more rigorously quantified. Testing will
determine the forces of dissection for various neurological tissues and
different
surgical procedures on human brains. This data will then be used to calibrate
force
thresholds for the warning safety system.
The data from clinical studies will be made available for incorporation
into surgical simulation software. Simulation models are currently based on
estimated forces, and therefore estimated tissue deformation. The force data
can be
used in conjunction with different brain tissue models to create more
realistic tool-
tissue interaction. In existing simulation software, mass-spring models and
finite
element methods are typically used. With the ability to more accurately record
forces
over time, improved modeling coefficient estimates (e.g. damping coefficients,
material constants, etc.) will be generated. These simulation models will
greatly
enhance the capability to provide surgeons with realistic case rehearsal and
training.
In order for surgical simulators to be an effective preparation for real
surgical
procedures, realistic feedback on the trainee's interactions with the virtual
tissues is
required. The more realistically the tool-tissue forces are simulated, the
more
effective the simulator will be in preparing the trainee for performance in
the
operating room (OR). Similar to the force warning safety system, the virtual
surgical
simulation environment can also benefit from an analogous feature. This
improvement can only be implemented if a safe range of realistic dissection
forces
for specific tissues is known. In the safety of a virtual simulation
environment, tool
CA 02820982 2013-06-28
9
force warning indicators would help surgical trainees to practice avoiding
tissue
damage during dissections. Before entering the OR, surgical trainees can
practice
on realistic surgical simulators and compare their simulation performance to
the
performance of experienced surgeons during real surgeries (where force data
was
collected). Video and tool-tip-forces can be recorded simultaneously, allowing
the
procedure to be replayed providing both video and haptic feedback (using the
Haptic
Forceps). This is one means of case rehearsal where a surgeon or trainee can
feel
the surgical forces as they watch procedures.
The arrangement described herein can easily be paired with a surgical
navigation system. This allows the tool to be registered in 3-D space,
enabling the
determination of position coordinates. Customized software can then monitor
the tip
position with respect to critical anatomical structures during a surgery. If
the tip
moves within a configurable threshold of a critical anatomical structure, the
warning
system is activated. In order to determine which critical anatomical zones to
avoid,
the software uses the pre-operative imaging data in conjunction with the
navigation
system and the surgeon's pre-operative input based on anatomical knowledge.
The arrangement described herein assists the ongoing development of
robotic tools. Presently tool-tip forces on a surgical robot are calculated
using the
force sensor measurements at the end-effector of a robotic manipulator. These
calculations are based on the kinematics and dynamics of the robotic
manipulator,
tool holder, and the surgical tool. Approximations are involved in these
calculations,
CA 02820982 2013-06-28
which introduce small force inaccuracies. Measuring forces directly at the
tool tip in
the arrangement described herein provide greater accuracy.
In any type of sensor, resolution and accuracy are the most important
characteristics. The resolution of a sensor is the smallest change in the
quantity of
5 measurement detectable by the sensor. Two different types of sensors can
be used
in the arrangement described herein.
The first approach relies on optical fiber Bragg grating (FBG) strain
sensors.
The second approach focuses on conventional strain gauges.
10 Each of these technologies has advantages and disadvantages.
The advantages of optical sensors include high sensitivity, small size,
fast response time, complete electrical isolation from other electronics, and
MRI
compatibility. This last characteristic is essential for use with MRI
compatible robots.
However, optical force sensors are much more expensive than conventional
strain
gauges (at least 20 times more). The optical-based sensor has superior
precision
and is MRI compatible, allowing it to be used inside the bore of an MRI
magnet. The
arrangement described herein can also use conventional strain gauges which are
cost effective and therefore more likely will be used for surgical training.
Moreover,
the low cost of the strain gauge forceps make them suitable to be provided in
disposable surgical tools.
The arrangement described herein using optical technology is highly
sensitive with a resolution of less than 1 millinewton.
CA 02820982 2013-06-28
11
Strain gauges are the most commonly used technology in force and
pressure sensors. A strain gauge is a device used to measure the strain, or
deformation, of an object. A strain gauge is usually a flexible foil pattern
that consists
of several thin conductive parallel wires sandwiched between two layers of
supporting material. It forms a resistive elastic unit, in which a change in
resistance
is a function of applied strain. Measuring forces using strain gauges is a
well-
established technology. Conventional strain gauges have been selected as an
option in this proposal because of their ease of use, low cost, and
established
reputation.
The principle of a strain gauge is based on changes in the resistance
of a wire correlated to increases and decreases in strain. When the strain
gauge is
properly attached to the surface of an object, strain to the object causes the
two to
deform together. This in turn changes the resistance of the strain gauge. To
convert
the change in resistance to strain, the sensitivity factor of the strain gauge
material
must first be determined. The sensitivity factor is different for different
strain gauge
materials. Thus, choosing a proper strain gauge according to the specific
application
is important. There are also other design factors that should be considered to
minimize error, such as variation due to temperature, linearity, hysteresis,
overloading, humidity, and repeatability.
One major issue is temperature compensation as bipolar forceps
produce heat during coagulation of tissue. One way of resolving this
temperature
issue, involves installing two strain gauges at each force-sensing site on the
forceps
CA 02820982 2013-06-28
12
prongs. One strain gauge will serve as a strain sensor, and the second will
act as
temperature reference, to compensate for errors caused by fluctuations in
temperature. These coupled strain gauges are mounted close enough to have the
same temperature; however one of them is isolated from strain. One way to
achieve
this is by having the temperature reference strain gauge mounted
perpendicularly to
the strain-sensing one.
The simplest design is to have one strain sensor installed on each
forceps prong. To achieve higher resolution, four strain sensors are required
(two on
each prong). Compensating for the effects of temperature variations requires
attaching eight strain sensors (four on each prong).
The strain sensors can be arranged in different configurations on the
forceps for measuring deformation with the greatest precision. Strain sensors
arranged for measuring the forces transverse to the prong of the forceps, that
is in
the direction of compression between the tips of the prongs or the
squeezing/dissecting forces (x-axis) can be placed on the inside and outside
of the
forceps prongs to achieve better precision. The best strain sensor placement
is
where the greatest deformation occurs on the prong of the tool, which varies
between different types of forceps. The arrangement described below shows the
sensor arrangement with the sensors on the inner and outer side faces of the
prongs
for measuring the squeezing/dissecting forces (x-axis). Theoretically, the
arrangement could also measure forces in the y-axis using the same concept
with
the sensors mounted on the top and bottom faces of the forceps prongs.
CA 02820982 2013-06-28
13
Measurement in the longitudinal direction of the prongs is also possible but
the
forceps would need to be physically modified to measure forces on the z-axis,
potentially affecting tool functionality. The precise sensor placement depends
on
specific forceps geometry. Placement of the sensors is located at the position
of
maximum deformation of the prongs during compression or squeezing and
therefore
maximum strain. The configuration of the sensors is arranged in adjacent
opposing
pairs.
Since strain sensor readings are based on material deformation,
material choices are highly relevant to forceps selection. As dissecting
bipolar
forceps already have an attached cable, the geometry of the tool is not
changed with
the addition of sensors and their wires. The ergonomics of the tool remains
identical
to that of conventional bipolar forceps, while adding accurate force
measurement
functionality.
A force calibration device customized for surgical forceps is provided to
allow strain sensor voltages to be mapped to actual forceps-tip forces. This
calibration device has a titanium Nano17 accurate force sensor installed in it
(ATI
Six-Axis Force/Torque sensor). The Nano17 titanium force sensor was chosen for
its
superior resolution and accuracy. The titanium version of this force sensor
has the
benefit of being MR-safe. These sensors can be calibrated with different
standards
to achieve various resolutions. For the arrangement described herein, the
force
sensor will use the SI-8-0.05 standard, since it provides the highest
resolution
(1/682N).
CA 02820982 2013-06-28
14
The arrangement described herein includes a display system with
integrated high-force warning safety feature (human interaction with digital
information).
The arrangement described herein includes a display system
component that allows the end-user (surgeon) to observe the instantaneous
force
readings at the tips of the tool. Surgeons may have different display system
preferences and by designing a modular system for displaying the force
readings,
the arrangement described herein provide a flexible and customizable solution
to the
end-user. The display system also provides optional audio alerts. Furthermore,
both
wireless and wired implementations can be provided for communication between
the
tool and the display system. The display system options include:
Wristband display system: force readings are displayed on a wristband
worn by the surgeon.
Eyeglasses display system: force readings are displayed non-
obtrusively on a pair of eyeglasses worn by the surgeon (similar to the Google
Glass
Project).
Tablet/ Smart Phone system: force readings are displayed on a mobile
device. This facilitates remote monitoring of a surgery for training purposes.
The knowledge of average dissection forces and maximum force limits
for different tissues is essential in the development of warning indicators
for tissue
dissection during surgery. One significant feature of the arrangement
described
herein is to provide a high-force warning safety system for use with force-
sensing
CA 02820982 2013-06-28
bipolar forceps. The force data collected from the pre-clinical and clinical
trials
indicates safe force ranges for different neurological tissue types during
various
surgical tasks. The tool can provide an audio, visual and/or haptic warning
when
approaching forces that could damage tissue. This warning system prevents
5 surgeons from damaging tissue unnecessarily, increasing patient safety and
improving outcome.
The tool (force-sensing) can be coupled with an existing set of forceps
with haptic actuation (force-generating), which allows the forces applied by a
surgeon during a surgery to be mirrored in the Haptic Forceps held by a
surgical
10 trainee. Currently, trainees observe surgeons at work, and use visual and
audio
feedback to anticipate the forces used for dissecting tissue. The addition of
haptic
feedback provides surgical trainees an effective means of feeling and
understanding
the forces applied during surgery, making the process of learning how to
perform
surgery more efficient.
15 The arrangement described herein can include a multi-platform
content
player application suite that allows modules of heterogeneous, platform-
independent
content to be written and deployed across various technology platforms
including,
but not limited to, iOS and Android mobile devices. The content modules can
contain
a mix of heterogeneous elements appropriate to a given operation or task such
as
dynamic simulations, plotting and analysis tools, hardware-in-the-loop
interaction,
2D/3D visualization, audio cues, as well as multimedia to enhance the
experience.
CA 02820982 2013-06-28
16
Since the forces exerted by the tool are small during microsurgical
tasks, the data acquisition system needs to have precise timing to reflect the
changes in forces while the tool is being used on different tissue types (e.g.
dissection of cranial nerve vs. fibrous tissues).
The arrangement described herein can include master-slave setups,
which consist of different haptic devices that act as master hand controllers,
and a
recently acquired industrial Kuka robot that acts as a slave. The original
control
system for the Kuka robot is customized to improve the control system sampling
time, as well as to provide the ability to remotely control the robot over an
ethernet
network via different master hand controllers.
The long-term benefits of improving surgical simulation are
widespread. Simulation allows trainees to learn and practice essential skills,
from
simple incisions to complex surgical scenarios, without the expense of
practicing on
a cadaver or the risk to a live patient. Surgeon training could become more
cost-
effective as a direct result of realistic simulation. Additionally, simulation
allows case
rehearsal, which will contribute to improved patient outcomes. Introducing new
safety features based on tool-tissue interaction forces will provide tangible
benefits
to patients.
The tool is both user-friendly and effective, increasing the likelihood of
achieving widespread adoption within the medical community. This technology
addresses a current gap in the medical field by introducing a digital
interface for
measuring tool-tissue interaction forces.
CA 02820982 2013-06-28
17
BRIEF DESCRIPTION OF THE DRAWINGS
One embodiment of the invention will now be described in conjunction
with the accompanying drawings in which:
Figure 1 is a schematic illustration of one embodiment of forceps
according to the invention.
Figure 2 is a view of the prongs only of the forceps showing the
arrangement of four strain gauges installed on a dissecting bipolar forceps,
Figure 3 shows the arrangement of the computer control of Figure 1
including a bridge configuration connected to a signal-conditioning box that
includes
a low-pass filter and amplifier.
Figure 4 is a graph showing a plot of force vs. voltage for calibration.
In the drawings like characters of reference indicate corresponding
parts in the different figures.
DETAILED DESCRIPTION
The figures include the following components:
1 ---Plugs for bipolar forceps tool power connection.
2 --Wires that connect embedded computer 3 to sensors 15 & 16
mounted on the bipolar forceps tool.
3 ---Miniature embedded computer system.
4 ---Signal conditioner, amplifier and low pass filter module.
5 --High-force warning system module.
6 ---High-temperature warning system module.
CA 02820982 2013-06-28
18
7 ---Wireless communications module.
8 ---Embedded display.
9---On-board data recording module.
10--Port for connecting on-board data recording module to external
computer.
11--Irrigation port.
12 ---Irrigation tube.
13 ¨Bipolar forceps tips are available in a range of different sizes.
14 ---Bipolar forceps prongs are available in a range of different
lengths (shorter for surface procedures and longer for deeper surgical
procedures).
¨Temperature sensors.
16 ¨Force sensors or strain gauges.
17 ---Coating on bipolar forceps prongs to allow for sterilization.
18 ---Secondary wireless display (optional).
15 19 ---Haptic actuator interface ports.
---bipolar forceps tool
21 ---handle
22 ---electrical supply system
23 ---irrigation actuation system
20 24 ---calibration device
---system control computer
26 ---haptic force-generating forceps
CA 02820982 2013-06-28
19
27 ¨data collection and transfer system
The embodiment shown in Figure 1 comprises a bipolar forceps tool 20
includes a pair of prongs 17 each having a prong tip 13 which are connected at
the
base or handle 21 for relative bending or squeezing movement of the prongs for
movement of the tips 13 into a tip contacting position.
Each of the prongs has a manually engageable portion 14A spaced
from the tip by a bend portion 14B for manual movement of the prongs to the
tip
contacting position by manual pressure on the manually engageable portion 14A.
An electrical supply system 22 is provided for applying a high-
frequency (in the radio frequency range of approximately 100kHz to 5MHz)
electric
current between tool tips 13 to dissect through tissue planes and/or seal
blood
vessels.
A series of force sensing components 16A to 16D and 16E to 16H are
provided on each prong for measuring forces applied to the prongs at the tip.
As
shown in Figure 2, these are arranged on the side faces of the rectangular
cross-
section of the prong which are at right angles to the X-axis in which the
compression
forces from squeezing the prongs together are measured. In the embodiment
shown, no sensors are mounted on the top and bottom faces of the prongs since
there is no measurement of forces in the Y-axis. However, in an alternative
arrangement (not shown) additional sensors can be mounted on these faces.
The forces in both prongs are detected in a composite or independent
manner in that the signals detected by the forces are transmitted through the
output
CA 02820982 2013-06-28
cable 2 consisting of a wire bundle having a plurality of individual
communication
wires to the computer for processing where they can be combined and analyzed
for
indication separately or as a combined force output signal.
One or both of the prongs also carries a temperature sensing
5 component 15A, 15B for measuring temperatures of tissue dissection and
coagulation in surgical procedures. This is located at or adjacent the tip so
as to be
closely responsive to the temperature of the surrounding tissue at the tip.
The force sensing and temperature sensing components 15, 16 are
protected by a protective coating/covering 17 on the prongs in such a way as
to
10 support standard medical sterilization procedures on the forceps. This
is particularly
provided as discussed above in an arrangement using high cost sensors which
require re-use.
The two types of sensors, strain gauges and optical force sensors, and
can be physically mounted on the surfaces of the prongs in different manner to
15 obtain the best connection. Preferably the mounting is by way of a
special adhesive
glue compound which ensures that the strain gauge follows the bending of the
material forming the prong without distortion.
As shown in the configuration in Figure 2, each prong carries four
sensing components 16A to 16H. This includes an arrangement for compensating
20 for temperature fluctuations during force measurement where the temperature
sensing component 15A, 15B is located at a position immediately adjacent the
sensors 16A to 16H respectively so as to be at a common temperature with the
force
CA 02820982 2013-06-28
21
sensing component and the temperature sensing device is arranged so as to be
non-responsive to the forces by being arranged perpendicular to the force
sensor so
as to provide a temperature compensation signal.
That is the temperature sensor is installed in such a way so as to be
isolated from strain to minimize strain on the temperature sensor as much as
possible to provide a temperature compensation signal.
As shown in Figure 3, the outputs of the force sensors 16A to 16D and
16E to 16H are connected in respective full-bridge electrical circuit
configurations to
the computer system 3 which manages the tool.
Also shown in Figure 2 is the arrangement of the sensors 16A to 16D
where two sensors 16A and 16B are one side face of the prong and the other
sensors 16C and 16D are on the opposite side face. Also the sensor 16A is
aligned
directly opposite the sensor 16C and the sensor 16B is directly opposite the
sensor
160. This arrangement of sensors together with the full bridge arrangement of
the
connection of their electrical outputs has been found to provide a very
effective
analysis of the forces and a final output which is closely proportional to the
squeezing force applied in the X-direction.
The computer system 3 includes a display 8 for displaying the forces
and temperatures of tissue dissection and coagulation in surgical procedures
present in both prongs of the bipolar forceps in a composite or independent
manner.
In addition the system includes a wireless communication module 7 for
communication with an exterior display 18 which can include embedded
electronic
CA 02820982 2013-06-28
22
displays, smart phones, tablets, computers, or augmented/virtual reality eye-
glasses.
The computer system 3 further includes a force warning system 5 that
indicates to the user when force thresholds are being exceeded via visual,
audio and
haptic means.
The computer system 3 further includes a temperature warning system
6 that indicates to the user when temperature thresholds are being exceeded
via
visual, audio and haptic means.
The tool includes an irrigation system for supplying irrigating fluid
though a duct 11 to be carried though channel (not shown) in one or both
prongs to
the tips, where an amount of irrigation is delivered when required either
controlled by
the surgeon in conventional manner or by the computer system 3 in the event
that a
temperature threshold is exceeded.
The computer system 3 includes a recording component 9 which
operates for translating accurate forces of dissection, based on force
recordings
from real surgeries. The component 9 operates to collect data at precise
timing to
reflect the changes in forces while the tool is being used on different tissue
types.
This data can be transferred to a system control computer 25 which contains
simulation software to create a training platform for novice surgeons with
increased
realism for tool-tissue interaction. The system of the computer 25 also
includes
haptic force-generating forceps 26 for operation in the training platform as
used by
training persons.
CA 02820982 2013-06-28
23
The wireless communication system 7 can also transfer data to a data
collection and transfer system 27 for collecting data from clinical studies to
be made
available for incorporation into surgical simulation software.
There is also provided a force calibration device 24 customized for the
surgical forceps 20 to allow strain sensor voltages actually detected by the
sensors
16 to be mapped to actual forceps-tip forces from the calibration device 24.
Thus four strain gauges 16A to 16H are installed on a dissecting
bipolar forceps. This bridge configuration is then connected to a signal-
conditioning
box 4 that includes a low-pass filter and amplifier. The output voltage of the
signal-
conditioning box 4 is connected to the analog input of a data acquisition
board,
which in turn is connected to a computer that reads and displays the voltages
on a
screen. A Nano17 force sensor is attached to a moving platform actuated by a
motor
and gearbox. The Nano17 force sensor is connected to its own signal
conditioning
box and data acquisition board (ATI and National Instruments). By pressing a
push
button, the motor is energized and the Nano17 force sensor moves towards the
tool
tip incrementally to increase the applied force at the tool tip. Forces
(measured by
Nano17) and voltages from the strain gauges are then used to obtain a force
vs.
voltage plot shown in Figure 5.
