Medical-Robotics

SPECIAL REPORT:
MEDICAL ROBOTICS
SEPTEMBER 2021
Sponsored by

ISO
9001
ISO
17025
ANSI
Z540-1
ISO
13485 U.S. Manufacturer
Giving robots
a sense of touch
FUTEK's miniaturized sensor technology
allows surgeons to perform as if they had
virtual fingertips. The sensors’ precise
measurement and feedback allow the
machine to emulate the dexterity and
haptics of human hands.
go.futek.com/medtech
LSB205
2 Miniature S-Beam Jr. Load Cell
Dimensions: 19 mm × 18 mm × 6.6 mm
Provides critical force feedback.
QLA401
3 Load Cell Built for Autoclave
Dimensions: Ø 14 mm × 3.28 mm
Designed to withstand the autoclave sterilization process.
QLA414
4 Nano Force Sensor
Dimensions: 4mm × 5mm
Enables direct measurement that eliminates any drift
in the output.
1
2
3
4
1
QTA143
1 Micro Reaction Torque Sensor
Dimensions: 14 mm × 10 mm × 26 mm
Provides closed-loop feedback on torque measurement.
Conceptual rendering of the
multi-jointed robotic arm of a
surgical system.

SEPTEMBER 2021 1
MEDICAL ROBOTICS SPECIAL REPORT
CONTENTS
ONTHECOVER
Minu
scule, self-propelled particles
called “nanoswimmers” can
escape from mazes as much as
20 times faster than other passive
particles. These particles could
navigate and permeate spaces
as microscopic as human tissue
to carry cargo and deliver drugs.
See page 20 to learn more.
(Image: Haichao Wu/University of
Colorado, Boulder)
FEATURES
2
Designing Rugged Myoelectric
Interfaces for Highly
Functional Prosthetics
7
Is a Medical Robot Really a
Robot?
10
Surgical Robotics: The Art of
Saving Costs with Cables
APPLICATION BRIEFS
14
Advancements in Robotic Magnetic
Navigation Technology Enhance Surgical
Processes
TECH BRIEFS
16
Ultra-Thin, Highly Sensitive Strain
Sensors Improve Robotic Arms
18
Dynamic Hydrogel Makes Soft Robot
Components and Building Blocks
20 Self-Propelled Nanorobots
21
Laser Jolts Microscopic Electronic
Robots into Motion
22
Low-Cost, High-Accuracy GPS-Like
System for Flexible Medical Robots
23
Smart Artificial Hand for Amputees

2 SEPTEMBER 2021
Designing
Rugged
Myoelectric
Interfaces
for
Highly Functional
Prosthetics
T
o use the laptops and
cellphones in today’s world,
modern prosthetic devices
connect signals from the brain
via surface-mounted sensors and
detectors. New sensor technologies
combined with high-performance micro-
wiring is extending the performance
and reliability of active myoelectric
prosthetics. The evolution of newly
developed microprocessor chip sensors
offers advanced communication
Implanted transducers that provide
kinesthetic communications of
force and vibration feedback are
particularly helpful in full leg and arm
prosthetics where activating multiple
muscles simultaneously is necessary.
(Credit: AdobeStock)

MEDICAL ROBOTICS SPECIAL REPORT SEPTEMBER 2021 3
from the brain to the prosthetic
devices. Myographic chips monitor
and measure the force produced
by muscles as they move from
relaxed mode to contractions and
can deliver intensity and muscle
signal speed. The surface-mounted
electromyographic sensors with
isolated micro-wiring receive analog
signals sent from the brain to be
captured and converted to digital
signals. They are then connected
to newly adapted prosthetic
devices that enhance the life and
capability of amputee patients.
Keys to quality human-to-machine
interface systems are extensive but
exacting and quite well defined.
Depending upon each circumstance,
options for directing prosthetic
movements include using body
power, electric assisted power, and
for simpler applications, passive or
pneumatic devices. The prostheses
method selected should optimize
the prosthetic device utilization for
patients and their life
styles. For
a number of years, industry has
focused on deep electromyography
(EMG) for collecting muscular
signaling from areas inside the
forearm for use with the prosthetic
hand. Today, however, surface level
electromyograms (sEMGs) have
significantly improved data-acquisition
capabilities, are noninvasive, and
have evolved to eclipse the surgical-
related prosthesis process.
Improving the Human-Machine
Interface
The data-processing system
consists of an electrode interface, a
signal conditioning unit, and a power
source designed into a small sealed
device. Getting a reliable and useful
signal from the sensors that drive
the machine in
struments requires
several steps. Two to three sensor
pads are carefully placed externally
on the arm at that point determined
to exhibit strong muscular signal
activity. Sensor placement must be
near the tendon bulge entering the
muscle to collect the best signals. This
ideal position of electrode placement
is between the innervation zone (or
motor unit) and where the muscle
tissue is attached to the tendons.
When the brain directs muscle
activity, the sensor pads detect
minute analog electrical signals that
result within the muscular system.
Those signals are filtered at both the
high and low frequencies to remove
electrical noise and to isolate the
signals from potential power supply
interference. In some cases, a variable
resistor is employed to act as a digital
potentiometer to help control signal
gain stability, as signals sometimes
bounce up and down during excited
use. The cleaned signals are then
rectified to offer a digital signal
that exhibits definable shifts in
voltage in typical range of 5–12 V.
In some cases, an amplifier is used
to set the signal levels and gain to
optimize wiring impedance and drive
mechanisms in the prosthetic unit. By
design, most prosthetic motor/driver
systems operate and provide more
precision in responding to low-level
digital stepping signal technology.
The complexity of this human-
to-machine interface increases
significantly the need to drive process
controls for multiple degrees of
freedom
in the prosthetic device.
Fortunately, these sEMGs are
improving and offering opportunities
for use beyond the older intramuscular
EMG prosthesis method. Surface-
style electrodes easily form a reliable
electrochemical state between the
detection surface and the skin of
the body so that current can flow
The National Institutes of Health supports additional development
of various EMG sensor devices and systems. (Credit: NIH)

4 SEPTEMBER 2021
into the electrodes. Because sensor
design and signal collection remains
the key element in the challenge, skin
preparation is critical, specifically in
the area of the sensor. One needs to
ensure good data acquisition
and clean signal transfer
to the amplifiers. Prior to
attachment, skin and hair
must be scrubbed to reduce
epidermis buildup and then
dried thoroughly before
application of the sensors.
To this end, neurological
signal detection electrodes
are being tested in a number
of formats. Both dry and
gel surface sensors have
been studied. Gel electrodes
use an electrolytic paste of
silicone imbedded with silver
chloride. This increases signal
conductivity and prevents
oxidation of the metal-to-skin
interface. When clean, the
electrical resistance is low
and the conduction is strong
enough to block outside
and surface-generated
signal noise as well. Dry
electrode sensors often use
small pre-amplifier modules
with multiple collection
dots and don’t use gels
between skin and device.
Though electronically
better, dry electrode
sensors are more vulnerable
to shock and vibration
and even sweat can
challenge circuit stability.
In many cases, the EMG
system assists the patient
in neurologically moving
parts using electrically
driven micro motors and/
or gears that can rotate
wrists, open and close
fingers, and pick up objects.
But beyond muscular
signal transmission,
newer prosthetics are
also employing sensory
feedback to the system
or the patient. Grip strength
and touch as well as pressure are
key elements required in mimicking
the natural use of the human limb.
Transducer electronics are included
to offer the classic control of picking
up an egg and not crushing it.
Implantable myoelectric sensors
(IMES) again paved the way to
improve limb control and detect
footing position and pressure. These
implanted transducers provide
great kinesthetic communications
of three-dimensional feel of
force and vibration feedback
to the patient. They are
particularly helpful in full leg
and arm prosthetics where
activating multiple muscles
simultaneously is necessary.
Simultaneous interaction
between multiple parts of the
operator became a significant
advance in prosthetic
applications such as hand and
arm control. The skin contains
biosensor chips that detect
variations in capacitance
and/or pressure, similar to
pressure sensors used in
robotic equipment. Nanoscale
microelectromechanical
systems (MEMS), chips, or
electrical capacitive sensing
field-effect transistors (FETs)
New sensor technologies enable the development of
prosthetic devices that enhance the life of amputee
patients. (Credit: AdobeStock)
Highly Functional Prosthetics
Future surface EMGs. (Credit: AdobeStock)
Specialized wire and cable designs are required
to protect and isolate the minute digital signals of
the EMGs from power wiring the motors. (Credit:
AdobeStock)

6 SEPTEMBER 2021
are used to provide haptic sense of feel
to reflect the pressure, touch, and pain
receptors in human skin. The skin is
electronically connected to the nerves
in the arm that are involved in relaying
sensations of touch and pain to the
brain. This process allows patients to
operate their new prosthetic hand in a
fashion similar to their original hand.
The Future of EMG Sensors
The National Institutes of Health
(NIH) and the National Institute of
Biomedical and Bioengineering have
continued to support additional
development of various EMG
sensor devices and systems. Two
evolving technologies use skin-
mountable systems and advanced
electronics. Beginning with the use
of pattern plated or 3D printing of
conductive circuitry on polyimide
thin-film sheets, there will likely be an
evolutionary development of rugged,
wearable, thin-film circuitry mounted
externally on the patient’s skin.
Sensor and motion control systems
for prosthetics have continued to
expand rapidly in both precision
capability and in operating more
extensive components. Compact
hand and foot control designs are
being extended to serve full leg
devices and exoskeleton systems.
Signal detection and data-processing
systems are somewhat extensions
of previous designs but routing of
directional signaling and response
information quickly becomes a
more detailed task because of the
distance they must travel. Physical
size of some prosthetic systems also
requires higher voltage or current
levels to operate devices like hip
and knee motors. The wiring and
interconnection physics of these
systems can become a challenge.
Specialized wire and cable designs
are required to protect and isolate
the minute digital signals of the
EMGs from the power wiring of the
motors. Electromotive interference
from outside environments
can confuse digital data
being routed to portions
of the prosthetic device.
Wire and cable must remain
relatively small and flexible
throughout constant use
and offer signal integrity
when exposed to elevated
temperatures, high humidity,
and sudden shock. Special
polarized-nano (PZN) and
circular nano-connectors
assist in connecting wire
to electronic elements
within the system.
Electromyography
and prosthetic device
development technology
has changed significantly.
From research centers to
medical device industry, the
process is well developed
and can rapidly develop
customized devices for
individual applications.
When designing intercon
nections for prosthetics, one
can begin by developing a
detailed list of personal use, physical
applications, and environmental
exposure. Working with experienced
electronic circuit designers and
using fast-turn prototyping systems
can rapidly enhance a system. By
employing the use of solid-modeling
software and working hand-in-glove
online with designers, OEMs can
develop the exact form and fit to
meet their specific function. When
the solid-model software appears
correct, they can be realized in 3D
built devices of each element and
a polymer mockup of the complete
prosthetic device can be constructed.
This would then allow preplanning the
signal routing system that best serves
a particular device system. Specialty
cable and connectors can be assembled
to match the needs of the device.
This article was written by Bob
Stanton, Director of Technology,
Omnetics Connector Corp., Minneapolis,
MN. For more information, visit
http://info.hotims.com/ 79409-341.
Highly Functional Prosthetics
When the brain directs muscle activity, the EMG sensor pads detect minute analog electrical signals that result
within the muscular system. (Credit: AdobeStock)

F
irst of all, there are
no true medical
robots; none of the
systems out there
called medical robots are
autonomous with regard
to duplicating human
activity and few are even
semi-autonomous. They are
arguably bionic constructs;
that is, enhancing the
healthcare provider’s
performance by electronic or
electromechanical devices.
The key here is that these
devices en
hance the abilities
of the user but do not replace
them. It is reasonably too
late to change the vernacular
and it is just a matter of
semantics anyway. But why
is this distinction important
to design and development?
This article addresses two
of the reasons why the
distinction is important:
•
The regulatory strategy
can be significantly
different from other
medical devices, especially
regarding the level of
autonomy, team usability
validation, and training.
•
Understanding that these systems
are an extension of a clinician’s
current ability and that they enhance
an activity that clinicians may
also do manually, thereby having
an important impact on the user
interface design and development.
Strategic Regulatory Impact
Even though many of the current
robotic systems are based on
technology that could very well execute
a procedure autonomously, the scope
of validating the safety and efficacy for
FDA approval would be cost prohibitive.
This is be
cause you would have to
demonstrate that the robot can safely
manage contingencies that are often
unpredictable during a procedure.
This would require validation trials
of a scale similar to pharmaceutical
clinical trials, where hundreds, if not
thousands of patients are required.
Unlike a medication, which is a high-
volume consumable that is reimbursed
by a payee, a piece of capital equipment
marketed to a healthcare facility does
not have the same return on investment
that could justify such an investment
in validation. However, by keeping
the clinician in control and the system
relegated to an extension of their
abilities, the human is still responsible
for the outcome. Now, with the clinician
as the decision-maker, the validation
process is a function of the clinician’s
interaction with the robotic system’s
user interface. In other words, the
manufacturer doesn’t have to validate
the user’s clinical abilities, just that the
robotic system meets expectations
for efficacy, safety, and performance.
That said, both the design and usability
validation can still be significantly more
complex than conventional
medical devices.
Using a surgical robotic
system as an example and
being an extension of the
surgeon’s abilities, the
robotic system impacts the
rest of the surgical workflow
as well — all the other actors
involved in the surgical
procedure. It is important
to note that a conventional
surgery, be it open or
laparoscopic, is typically a
symphony of interactions
between a team of clinicians.
These clinicians may include
lead surgeon, first assist,
sterile nurse/tech, circulating
nurse, anesthesiologist,
and possibly others (e.g.,
perfusionist) or duplicates
of some of the actors listed.
In addition, if it is a teaching
hospital, there are interns
and fellows on the team.
Understanding all the
people involved in order
to result in a favorable
outcome for the patient
is important because now
we are introducing a new
actor into the operating room: the robot.
Oftentimes, this impacts the manner
in which the lead surgeon interacts
with the team as well as requiring a
physical footprint for the robotic system
in an already congested environment.
Moreover, once you remove the team
leader from the sterile field and isolate
that participant in a control console, the
team dynamics are profoundly impacted.
Although the intention is often to make
the robot an optimized instrument(s)
for the surgeon, in application, it can
affect the responsibilities of the extended
surgical team and their responsibilities.
For example, there may be a requirement
to exchange end effectors over the
course of the procedure, which requires
team members to interact with each
other and the robot, while the lead is
interacting with them without face-to-
face communication. Keep in mind that
IS A MEDICAL ROBOT
REALLY A ROBOT?
Robotic systems are an extension of a clinician’s current ability and enhance
an activity that they may also do manually.
Design and usability validation of robots can be significantly more complex
than conventional medical devices. (Credit: Sompong Sriphet)

8 SEPTEMBER 2021
a significant portion of communication
is nonverbal. Granted, the actors are
wearing masks, but they have learned
to read facial expressions inclusive of
the mask in addition to body posture.
The point of understanding these team
dynamics is that when it comes time to
validate the user interface of the robotic
system, the team has to be considered
and often included in the validation test.
Moreover, the teams may or may not be
cohesive; that is, in a teaching hospital,
the team members may change often,
whereas in a private institution, they
may be a seasoned, cohesive team. For
usability validation, both team types
would need to evaluate the design.
Even more important is that upstream
usability engineering research must be
conducted in order to inform the design
and regulatory team of the requirements
for future validation based on well-
understood, use-related risk assessments.
The use-related risk assessment
can impact yet another regulatory
path strategy for a robotic system,
complicating risk mitigation and the
subsequent validation. This specifically
involves training models for the robotic
system. Legacy manual surgical devices
typically do not require formal training;
i.e., training beyond orientation or an
“in service.” The difference between
orientation and formal training is
that orientation is not considered
a risk mitigation from a regulatory
perspective. In order for training to be
a risk mitigation or design control, it
has to have robust documentation that
demonstrates to the regulatory bodies
the degree of control and repeatability
the manufacturer maintains.
This means that under the design
control process, there is a protocol
for how the trainer is trained, a record
of who was trained, when they were
trained, if and when subsequent training
is required, and what qualifications
for use of the system the training
results in. The definition of system may
include the robot proper, the control
console, the robot drapes and the end
effector’s instrument attachments.
It may even include the cleaning
and reusability of the instrument
attachments. Obviously, formal training
is a far greater ongoing burden and
responsibility for the manufacturer.
User Interface Design Impact
The team dynamics and the impact
of the introduction of a robotic
system into a surgical procedure have
comparable influence to the regulatory
impact with regard to the design and
development of all the system’s user
interfaces — virtual and physical. The
same user research insights that can
inform the use-related risk assessment
and regulatory strategy apply to
the design and development of the
robotic system’s user interface.
Consider the example of the lead
surgeon’s user interface: there is first
the understanding of negative and
positive transfer bias in the physical
user interface. This also applies to
the cognitive load requirements of
the system, especially if the system is
expecting the surgeon to be responsible
for what was previously a team effort.
Then there is the accommodation of
team dynamics and communication
as discussed in the regulatory strategy
impact. These considerations also apply
to the other user interfaces such as
end effector access to the anatomy,
instrument attachment and draping.
Returning to the surgeon’s user
interface example and the associated
biases, the manner in which the
surgeon executes a manual procedure,
the variety of instruments and their
specific user interfaces, the instruments’
capabilities, kinematics, and feedback
can result in either a positive or negative
transfer bias, depending on how the
new control interface is designed.
Negative transfer bias can introduce
a potentially hazardous condition and
use error that could lead to harm —
changing the rote manner in which
a task is performed relative to how it
was learned and practiced previously.
Conversely, the user interface design
can afford positive transfer bias by
emulating or carefully transitioning from
a norm behavior and interface to the new
user interface and workflow experience.
Depending on training to convert the
user’s previously learned skills and
behavior is not a viable strategy. A pro
active approach to understanding the
user’s expectation and aspiration with an
in-depth understanding of the perceived
attributes that afford the intended
behavior is a more robust approach.
This article was written by Sean Hägen,
Founding Principal and Director of
Research Synthesis at BlackHägen
Design, Dunedin, FL. He focuses on the
user research and synthesis phases of
product development including usability
engineering, user-centric innovation tech-
niques, and establishing user require-
ments. For more information, visit
http://info.hotims.com/79411-343.
The definition of system may include the robot proper, the control console, the robot drapes, and
the end effector’s instrument attachments.
Medical Robot

10 SEPTEMBER 2021
E
ver hear of the respected
bicycle manufacturer known
as Can
non
dale? You probably
have. Perhaps you even own
one of their bikes. I actually do.
Since 1971, Cannondale has produced
among the most well-recognized and
trusted high-performance bicycle
brands in the United States. But
they don’t make gear systems.
For that matter, Cannondale
doesn’t produce hand grips, seats,
rims, spokes, hubs, sprockets, or
chains. Even the paint used to
beautify their venerated machines
isn’t actually made by Can
nondale.
The truth is that Cannondale makes
bike frames. Everything else is
sourced from a trusted stable of
suppliers that Cannondale
has carefully vetted to ensure
that every component their
bikes are made from meets
the maker’s rigid standards.
And even though Cannondale
does not manufacture more
than the bike frame itself, we
still turn to Cannondale to
sell us a whole bike — well,
unless one is a cycling purest
that assembles bicycles one
part at a time. For the rest
of us though, we’d prefer to
just be given the entire bike.
The da Vinci Surgical
System, currently among the
world’s most popular surgical
robots, is a veritable labyrinth
of components. From plastics
to wires, and from pulleys to
cables, their robot is made up
of countless parts. And just
like Can
nondale, the surgical
robot’s maker, Intuitive, does
not actually manufacture the
smorgasbord of components
contained within a single
da Vinci robot. Similarly,
as a manufacturer of
some of the key motion
control components of
surgical robots, Carl
Stahl Sava Industries
likewise does not actually
manufacture everything that a
cable assembly may comprise.
In each of these scenarios — the
bike and the shifters, or the surgical
robot and the cables — turning to
a single source for the completed
product is the way these products
are typically sold. So, like one buys
a whole bike from Cannondale,
one buys a whole robot from
Intuitive. Unless one does not.
You see, unlike the aforementioned
deeply respected bike and surgical
robot makers, too often, customers
purchasing precision components
do not use a single source. Rather
frequently actually, the makers
of today’s most modern surgical
robots, for instance, will use multiple
component makers and have
each section shipped to multiple
sources and leave assembly to,
well, multiple manufacturers. While
necessary in some workflows,
the objective should always be to
limit the number of components
changing hands in an urgent effort
to outpace global competitors.
Said plainly, the more turnkey
a supplier can be, the lower the
exposure to increased costs, a lack of
accountability, and ultimately painful
delays. Taken individually, any of the
three — cost, liability, or delay — is
enough to put a device maker at
the back of the line, because make
no mistake, in the world of surgical
robots, the market is proliferating,
Surgical Robotics:
THE ART OF SAVING COSTS WITH CABLES
Plasma-welded 7x37 tungsten mechanical cable used to power a motion control system in the miniature
actuators of a surgical robotics application. (Credit: Carl Stahl Sava Industries)

and how fast a robot goes to
market is directly tied to how
quickly a source can produce
and assemble components.
Cost, Accountability,
Delays: The Three
Killers of Competitive
Advantage
“If a tree falls in a forest
and no one is around to
hear it, does it make a
sound?” This well-known
metaphysical question has
popularized a centuries-
old debate. If the tree
is capable of making a
sound as it falls, then yes,
the tree made a sound. If,
however, no one is there to
hear the sound of it falling,
philosophically speaking,
the tree didn’t actually
make a peep. And were the
tree a pint-sized sapling or
perhaps a mighty sequoia,
the debate would rage on
regardless. The point is, if a
company is making the most
revolutionary surgical robot the
world has ever seen — the sequoia
— but is mired in holdups, who
cares? The possibly more pressing
question is, who should care?
Surgical robotics is a booming
and fast-paced marketplace. There
is quite literally no time to wait. As
a mechanical cable components
manufacturer, customers order
individual parts all the time — say, a
fixed length of cable, cut to specific
size, along with 1,000 of this and
500 of that. And if no questions
are asked during these early and
seemingly commonplace sourcing
conversations, the parts are made,
packed, shipped, and the transaction
completed. In this case, however, the
buyer is charged à la carte piece part
pricing and leaves the robot maker’s
procurement teams to manage
multiple vendors, multiple quality
apparatuses, multiple deliveries,
and consequently, multiple points
of potential failure. Worse, when
components don’t fit properly
with mating parts or there’s a burr
in a fitting, who’s to blame?
Perhaps another party damaged
delicate end-fittings meant to
be crimped to a length of wire
rope. Maybe parts were damaged
in a press, revealing microscopic
imperfections that prevent the
smooth joining of components.
While working without the benefit
of a single point of accountability,
prices start to soar, fingers start
to point, and production starts
to stop. When these are the
prevailing characteristics of a
sourcing transaction, the tree
may have fallen in the woods but
no one’s going to hear a thing.
Vet the Whole Source
Surgical robots take years to
bring to market and even when
they do become widely available,
makers like Intuitive are unrelenting
in their focus on rolling out the
next model. So, the production of
tomorrow’s version is perpetually
underway, while consumption
of the current one grows.
Add to the lengthy exercise in
simply advancing the prevailing
technology, and there is the
ocean of regulatory and quality
certifications these sophisticated
surgical instruments require. The
fact is, it is easy to imagine how
long it takes to produce a single
prototype, let alone an entire family
of robots, and get them into the
hands of awaiting surgeons around
the world. With such an interminable
production cycle baked into the
entire surgical robotics industry, any
go-to-market delay can irreversibly
damage market share potential.
These prodigious innovations
in modern medicine therefore
benefit from equally impressive
7x37 tungsten mechanical cable with swaged stop plug on the ends. This cable assembly is used to support
motion in a surgical robotics application. (Credit: Carl Stahl Sava Industries)

12 SEPTEMBER 2021
innovations in the actual production
of the devices themselves. Surgical
robotics makers, for example,
often ask component makers
like Sava about the potential to
deploy a cellular manufacturing
environment surrounding the
making of key components.
So, not only are components makers
asked, “Can you make it?” but as
critically, albeit less ceremoniously,
they are also asked tough questions
like, “how will you do it, who will
do it, and how many can you do?”
The list goes on and on and maybe
surprisingly so, these are among the
most frequently asked questions
on which components makers are
pressed — and with good reason.
Production can’t take a sick day
because someone got the sniffles.
A burr in a cable fitting cannot hold
up the entire day’s productivity.
A dedicated manufacturing cell
pledges materials and equipment
along with key and redundant
skilled operations, finishing and
quality personnel to production. As
cellular production is streamlined,
time is recovered and production
tempos improve. The coalescing
of talent, technology, speed,
and accountability represents an
arrant recovery of time getting
a surgical robot to market.
Seeing the Big Picture
There are many ways to do many
things. No one is arguing that there
is a single right and wrong way to
source components for the latest in
surgical robotics technology. Sources
abound in a global economy now
designed to offer surgical robotics
makers the freedom to choose
from a massive pool of suppliers.
The question is therefore not
necessarily what options are
available but rather what options
give the robot maker a wider stride
than their competitors. As a maker
of the very motion control cable
going inside these marvels, there
is no single metaphor that should
better characterize the speed of a
robot maker’s go-to-market strategy
than a “gazelle’s stride.” And if
sourcing from multiple suppliers
gets components purchased and
assembled, yet at the hindrance
of that stride, well then, a sequoia
just came tumbling down without
a sound. Where years have been
spent, millions invested, and billions
at stake, a case can be made for
reducing variability in every facet
of production, despite the alluring
availability of ubiquitous sourcing
alternatives and methodologies.
This article was written by Scott
Dailey, Vice President of Sales and
Marketing, Carl Stahl Sava Industries,
Riverdale, NJ. For more information,
visit http://info.hotims.com/79409-
345.
0.035 diameter balls being swaged to 0.024 7x19 stainless steel mechanical cable used in a surgical implantable instrument. (Credit: Carl Stahl Sava
Industries)
Surgical Robotics

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14 SEPTEMBER 2021
APPLICATIONBRIEFS
Advancements in Robotic Magnetic Navigation Technology Enhance
Surgical Processes
Robots are revolutionizing
the field of medicine. From
critical procedures to routine
tasks, physicians and hospitals are
adopting the use of this advanced
technology to reduce costs, enhance
precision, and increase safety. The
use of Robotic Magnetic Navigation
(RMN) in electrophysiology was
introduced a decade ago and
continues to evolve. One surgical
robot company, St. Louis–based
Stereotaxis, recently received
FDA approval for its Genesis RMN
system. Stereotaxis is a global
leader in innovative robotic technologies
designed to enhance the treatment of
arrhythmias and perform endovascular
procedures. The Genesis is the first
system to treat cardiac arrhythmias.
The innovative Genesis system
offers the proven benefits of RMN in
a design that is faster, smaller, lighter,
and more flexible. The system consists
of two robotically controlled magnets
positioned on flexible and rugged
robotic arms that are located next
to the operating table. During the
procedure, a physician uses a computer
interface to adjust the magnetic field
around the patient, directing and
steering the magnetic catheter inside
of the patient with extreme precision.
The system’s small size improves
the patient experience while on the
operating table and provides medical
personnel with greater access to
the patient during the procedure.
Committed to optimizing overall
operating performance of the machine
and providing an enhanced experience
for the patient, Stereotaxis initiated an
assessment of the Genesis. THK, a
linear motion component supplier to
Stereotaxis, analyzed and identified
linear motion components that could
be replaced by dropping in the THK
component and eliminating any
need for a redesign of the Genesis.
THK experienced sales and design
engineers collaborated to make
determinations and validate their
findings. A roller bearing inside the
robotic arms of the machine was
replaced with a THK Type RB cross
roller ring. Data indicated that the
Type RB offers increased accuracy,
the ability to bear heavier loads, and
improved rigidity. This upgrade resulted
in a more robust design with a greatly
enhanced life expectancy compared
to the original bearing. The Type
RB features inner ring rotation. The
outer ring is separable while the inner
ring is integrated with main body.
On the linear axis of the machine,
THK suggested replacing the current
component with the THK Type SHS25
linear motion guide. The Type SHS
utilizes patented THK Caged Ball
technology that eliminates friction
between balls, achieves low noise,
offers long-term maintenance-free
operation, and provides a high-
speed response. The Type SHS also
features four-way equal load. The
Type SHS LM block can receive a
well-
balanced preload, increasing
the rigidity in the four directions
(radial, reverse-radial, and lateral
directions) while maintaining a
constant, low friction coefficient.
With the low sectional height and
the high rigidity design of the
LM block, the Type SHS achieves
highly accurate and stable linear motion.
A third component, the THK Type
BNT precision ground ball screw, was
recommended as a replacement. The
Type BNT is a high-efficiency feed
screw with the ball making a rolling
motion between the screw axis and
the nut. Compared with a conventional
sliding screw, this product has drive-
torque of one-third or less, resulting in
drive motor power savings. Mounting
screw holes are drilled on the square
ball screw nut of the Type BNT,
allowing it to be compactly mounted
on a machine without a housing.
Having successfully incorporated
THK into other designs, Stereotaxis
was confident that these components
would not only bring longer life and
higher accuracy to its design, but
most importantly, they would help
to provide a superior experience for
patients being treated in hospitals
and clinics with Stereotaxis Genesis
technology. A key advantage to using
THK components in the Genesis was
that THK was able to provide improved
solutions using components that fit
into the existing design, rather than
requiring Stereotaxis to go back to
the drawing board and spend valuable
resources on an already proven design.
To learn more about Stereotaxis,
visit www.stereotaxis.com. For more
information about THK America, Inc.,
Schaumburg, IL, call (847) 310-1111 or visit
http://info.hotims.com/79415-345.
The Stereotaxis Genesis robotic magnetic navigation system.
Left:THKTypeSHSLMguidewithpatentedCagedBalltechnologyachieveshighlyaccurateandstablelinear
motion.Center:THKTypeRBcrossrollerringoffersincreasedaccuracy,theabilitytobearheavierloads,and
improvedrigidity.Right:THKTypeBNTprecisiongroundballscrewprovidesdrivemotorpowersavings.

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16 SEPTEMBER 2021
TECHBRIEFS
Assistant Professor Chen Po-Yen
has taken the first step toward
improving the safety and precision of
industrial robotic arms by developing
a new range of nanomaterial strain
sensors that are 10 times more sensitive
when measuring minute movements,
compared to existing technology.
Fabricated using flexible,
stretchable, and electrically conductive
nanomaterials called MXenes, these
novel strain sensors are ultra-thin
and battery-free, and they can
transmit data wirelessly. With these
desirable properties, the novel strain
sensors can potentially be used for
a wide range of applications.
“Performance of conventional
strain sensors has always been
limited by the nature of sensing
materials used, and users have
limited options of customizing the
sensors for specific applications,”
says Chen, who is from NUS Chemical
and Biomolecular Engineering. “In
this work, we have developed a
facile strategy to control the surface
textures of MXenes, and this enabled
us to control the sensing performance
of strain sensors for various soft
exoskeletons. The sensor design
principles developed in this work will
significantly enhance the performance
of electronic skins and soft robots.”
Precision Manufacturing
One area where the novel strain
sensors could be put to good use is in
precision manufacturing, where robotic
arms are used to carry out intricate
tasks such as fabricating fragile
electronic products like microchips.
These strain sensors can be coated
on a robotic arm like an electronic
skin to measure subtle movements as
they are stretched. When placed along
the joints of robotic arms, the strain
sensors allow the system to understand
precisely how much the robotic
arms are moving and their current
position relative to the resting state.
Current off-the-shelf strain sensors do
not have the required accuracy and
sensitivity to carry out this function.
Conventional automated robotic
arms used in precision manufacturing
require external cameras aimed at
them from different angles to help
track their
positioning and movement.
The ultra-
sensitive strain sensors will
help improve the overall safety of
robotic arms by providing automated
feedback on precise movements with
an error margin below one degree and
remove the need for external cameras
as they can track positioning and
movement without any visual input.
“Our co-developed wireless sensors
with customer-designated sensing
performance allow the robots to
conduct high-precision motions and
the feedback sensing data can be
transmitted wirelessly, which cohere to
the approaches of Realtek Singapore
in wireless smart factory. Realtek
will continue to build up a strong
collaboration with NUS, and we look
forward to bringing the technologies
from the lab to market,” says Dr. Yeh
Po-Leh, chairman of Realtek Singapore.
Customizable, Ultra-Sensitive
Sensors
The technological breakthrough
is the development of a production
process that allows the NUS researchers
to create highly customizable ultra-
sensitive sensors over a wide working
window with high signal-to-noise
ratios. A sensor’s working window
determines how much it can stretch
while still maintaining its sensing
qualities and having a high signal-to-
noise ratio means greater accuracy
as the sensor can differentiate
between subtle vibrations and minute
movements of the robotic arm.
This production process allows
the team to customize their sensors
to any working window between 0
and 900 percent while maintaining
high sensitivity and signal-to-noise
ratio. Standard sensors can typically
achieve a range of up to 100 percent.
By combining multiple sensors
with different working windows,
NUS researchers can create a single
Ultra-Thin, Highly Sensitive Strain Sensors Improve Robotic Arms
The sensors improve the safety and precision of industrial robotic arms.
National University of Singapore
Ten times more sensitive than conventional technologies, these lightweight strain sensors can be
incorporated into rehabilitation gloves to improve their sensitivity and performance. (Credit: NUS)

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18 SEPTEMBER 2021
Using a new type of dual-polymer
ma
terial capable of responding
dynamically to its environment, re
searchers have developed a set of
modular hydrogel components that
could be useful in a variety of soft
robotic and biomedical applications.
The components, which are
patterned by a 3D printer, are
capable of bending, twisting, or
sticking together in response to
treatment with certain chemicals. The
researchers created a soft gripper
capable of actuating on demand
to pick up small objects, as well as
LEGO-like hydrogel building blocks
that can be carefully assembled
then tightly sealed together to
form customized microfluidic
devices — “lab-on-a-chip” systems
used for drug screening, cell
cultures, and other applications.
The key to the new material’s
functionality is its dual-polymer
composition; one polymer provides
structural integrity while the other
enables the dynamic behaviors
like bending or self-adhesion.
Hydrogels solidify when the polymer
strands within them become tethered
to each other — a process called
crosslinking. There are two types of
bonds that hold crosslinked polymers
together: covalent and ionic. Covalent
bonds are quite strong but irreversible.
Ionic bonds are not quite as strong
but can be reversed. Adding ions will
cause the bonds to form and removing
ions will cause the bonds to fall apart.
For the new material, the researchers
combined one polymer that’s covalently
crosslinked (called PEGDA) and one
that’s ionically crosslinked (PAA).
PEGDA’s strong covalent bonds hold
the material together while the PAA’s
ionic bonds make it responsive. Putting
the material in an ion-rich environment
causes the PAA to crosslink, meaning
it becomes more rigid and contracts.
Take those ions away, and the material
softens and swells as the ionic bonds
break. The same process also enables
the material to be self-adhesive when
desired. Put two separate pieces
together, add some ions, and the
pieces attach tightly together.
That combination of strength
and dy
namic behavior enabled the
researchers to make a soft gripper.
Each of the gripper’s “fingers” was
ultra-sensitive sensor that would
otherwise be impossible to achieve.
The research team took two years
to develop this breakthrough and
have since published their work in
the scientific journal ACS Nano. They
also have a working prototype of the
application of the soft exoskeletons
in a soft robotic rehabilitation glove.
“These advanced flexible sensors
give our soft wearable robots an
important capability in sensing
patient’s motor performance,
particularly in terms of their range
of motion. This will ultimately enable
the soft robot to better understand
the patient’s ability and provide the
necessary assistance to their hand
movements,” says Associate Professor
Raye Yeow, who heads a soft robotics
lab in NUS Biomedical Engineering
and leads the soft and hybrid
robotics program under the National
Robotics RD Programme Office.
Robotic Surgery
The team is also looking to
improve the sensor’s capabilities
and is working with Singapore
General Hospital to explore
the application of the sensors
in soft exoskeleton robots for
rehabilitation and in surgical robots
for transoral robotic surgery.
“As a surgeon, we rely on not
just our sight but also our sense
of touch to feel the area inside the
body where we operate. Cancerous
tissues, for instance, feel different
from normal, healthy tissue. By
adding ultra-thin wireless sensing
modules to long robotic tools, we
can reach and operate in areas where
our hands can’t reach and potentially
feel the tissue stiffness without the
need for open surgery,” says Dr.
Lim Chwee Ming, senior consultant,
Otorhinolaryngology-Head Neck
Surgery, Singapore General Hospital.
For more information, visit https://
news.nus.edu.sg.
Dynamic Hydrogel Makes Soft Robot Components and Building Blocks
The hydrogel material could make assembling complex microfluidic or soft robotic devices as
simple as putting together a LEGO® set.
Brown University, Providence, Rhode Island
A new kind of hydrogel material has the
ability to react dynamically to its environment
— bending, twisting, and self-adhering on
demand. The self-adhering behavior is shown
on the tail of a 3D-printed hydrogel salamander.
The self-adhering behavior was also used to
make hydrogel building blocks that fit together
like LEGO bricks. (Wong Lab/Brown University)
TECH BRIEFS

20 SEPTEMBER 2021
patterned to have pure PEGDA on
one side and a PEGDA-PAA mixture
on the other. Adding ions caused
the PEGDA-PAA side to shrink and
strengthen, which pulled the two
gripper fingers together. The setup
was strong enough to lift small
objects weighing about a gram
and hold them against gravity.
The new material — and the LEGO
block concept it enables — allows
complex microfluidic architectures
to be incorporated into each block.
Those blocks can then be assembled
using a socket configuration much
like that of real LEGO blocks.
Adding ions to the assembled
blocks makes a water-tight seal.
For more information, contact Kevin
Stacey at kevin_stacey@brown.edu;
401-863-3766.
Self-Propelled Nanorobots
The “nanoswimmers” could be used to remediate contaminated soil, improve water filtration,
or even deliver drugs to targeted areas of the body.
University of Colorado, Boulder
Researchers have discovered
that minu
scule, self-propelled
particles called “nanoswimmers”
can escape from mazes as
much as 20 times faster than
other passive particles. The tiny
synthetic nanorobots are incredibly
effective at escaping cavities
within maze-like environments.
The nanoswimmers came to the
attention of the theoretical physics
community about 20 years ago and
people imagined a wealth of real-
world applications. Unfortunately,
these tangible applications have not
yet been realized, in part because
it’s been quite difficult to observe
and model their movement in
relevant environments until now.
These nanoswimmers, also
called Janus particles, are tiny
spherical particles composed
of polymer or silica, engineered
with different chemical properties
on each side of the sphere. One
hemisphere promotes chemical
reactions to occur but not the
other. This creates a chemical field
that allows the particle to take
energy from the environment and
convert it into directional motion,
also known as self-propulsion.
In contrast, passive particles that
move about randomly (a kind of
motion known as Brownian motion)
are known as Brownian particles.
The researchers converted these
passive Brownian particles into
Janus particles (nanoswimmers)
for this research. Then they made
these self-propelled nanoswimmers
try to move through a maze made
of a porous medium and compared
how efficiently and effectively they
found escape routes compared to
the passive, Brown
ian particles.
The Janus particles were effective
at escaping cavities within the maze
— as much as 20 times faster than
the Brownian particles — because
they moved strategically along the
cavity walls searching for holes,
which allowed them to find the exits
very quickly. Their self-propulsion
also appeared to give them a boost
of energy needed to pass through
the exit holes within the maze.
While the particles are incredibly
small — about 250 nanometers
or just wider than a human hair
(160 nanometers) but still much
smaller than the head of a pin (1-2
millimeters) — the work is scalable.
This means that these particles
could navigate and permeate
spaces as microscopic as human
tissue to carry cargo and deliver
drugs as well as through soil
underground or beaches of sand
to remove unwanted pollutants.
The next step is to understand
how nanoswimmers behave in
groups within confined environ
ments or in combination with
passive particles. One of the main
obstacles to reaching this goal is
the difficulty involved in being able
to observe and understand the 3D
Top: A schematic diagram showing the
observation of particles moving through a generic
porous material. Bottom: A representative
scanning electron microscopy image of inverse
opals, the porous medium used in this research.
Large circular patterns indicate the close packed
cavities and small elliptical patterns indicate the
holes connecting adjacent cavities. Every cavity
was connected to its adjacent cavities through 12
holes. (Credit: Haichao Wu)
1 µm
TECH BRIEFS

Laser Jolts Microscopic Electronic Robots into Motion
Incorporating semiconductor components, microscopic robots are made to walk with
standard electronic signals.
Cornell University, Ithaca, New York
Ateam has created microscopic
robots that incorporate semi
conductor com
ponents, allowing them
to be controlled — and made to walk
— with standard electronic signals.
The robots are about 5 microns thick,
40 microns wide, and range from 40
to 70 microns in length — roughly
the same size as mi
croorganisms like
paramecium. These robots provide
a template for building even more
complex versions that utilize silicon-
based intelligence, can be mass-
produced, and may someday travel
through human tissue and blood.
The new robots each consist of
a simple circuit made from silicon
photovoltaics — which essentially
functions as the torso and brain
— and four electrochemical
actuators that function as legs.
Since there were no small,
electrically activatable actuators
that could be used, the team had
to invent them and then combine
them with the electronics.
Using atomic layer deposition and
lithography, they constructed the
legs from strips of platinum only
a few dozen atoms thick, capped
on one side by a thin layer of inert
titanium. Upon applying a positive
electric charge to the platinum,
negatively charged ions adsorb
onto the exposed surface from the
surrounding solution to neutralize
the charge. These ions force the
exposed platinum to expand, making
the strip bend. The ultra-thinness
of the strips enables the material to
bend sharply without breaking. To
help control the 3D limb motion, the
researchers patterned rigid polymer
panels on top of the strips. The
gaps between the panels function
like a knee or ankle, allowing the
legs to bend in a controlled manner
and thus generate motion.
The robots are about 5 microns thick, 40
microns wide, and range from 40 to 70
microns in length — roughly the same size as
microorganisms like paramecium. (Image:
Cornell University)
The microscopic robots consist of a simple circuit made from silicon photovoltaics — essentially
the torso and brain — and four electrochemical actuators that function as legs. When laser light is
shined on the photovoltaics, the robots walk. (Image: Cornell University)
movement of these tiny particles
deep within a material comprising
complex interconnected spaces.
This hurdle was overcome by
using refractive index liquid in
the porous medium — liquid that
affects how fast light travels
through a material. This made
the maze essentially invisible
while allowing the observation
of 3D particle motion using a
technique known as double-helix
point spread function microscopy.
This enabled the team to track
three-dimensional trajectories
of the particles and create visual
representations, without which it
would not be possible to better
understand the movement and
behavior of either individuals
or groups of nanoswimmers.
For more information, contact the
Media Relations team at cunews@
colorado.edu; 303-735-0122.

22 SEPTEMBER 2021
Low-Cost, High-Accuracy, GPS-Like System for Flexible Medical Robots
This easy-to-use system tracks the location of flexible surgical robots inside the human body.
University of California, San Diego
The GPS-like system includes the robot, magnets, and magnet localization setup. (Credit: David Baillot/
University of California San Diego)
The researchers control the robots
by flashing laser pulses at different
photovoltaics, each of which charges
up a separate set of legs. By toggling
the laser back and forth between
the front and back photovoltaics, the
robot walks. The robots are compatible
with standard microchip fabrication
and operate with low voltage
(200 millivolts) and low pow
er (10
nanowatts). Because they are made
with standard lithographic pro
cesses,
they can be fabricated in parallel: about
1 million bots fit on a 4 silicon wafer.
The researchers are exploring
ways to equip the robots with more
complicated electronics and onboard
computation — improvements that
could one day result in swarms
of microscopic robots crawling
through and restructuring materials,
suturing blood vessels, or being
dispatched en masse to probe
large swaths of the human brain.
For more information, contact
Jeff Tyson at jeff.tyson@cornell.edu;
607-793-5769.
Roboticists have developed an
affordable system to track
the location of flexible surgical
robots inside the human body.
The system performs as well as
current state-of-the-art methods
but is much less expensive.
Many current methods also
require exposure to radiation,
while this system does not.
Continuum medical robots
work well in highly constrained
environments inside the body.
They are inherently safer and
more compliant than rigid tools;
however, it becomes more
difficult to track their location
and their shape inside the body.
The researchers embedded a
magnet in the tip of a flexible
robot that can be used in delicate
places inside the body such as
arterial passages in the brain.
They worked with a growing robot,
which is a robot made of a very thin
nylon that is inverted and pressurized
with a fluid that causes the robot to
grow. Because the robot is soft and
moves by growing, it has very little
impact on its surroundings, making
it ideal for use in medical settings.
They then used existing magnet
localization methods, which work
very much like GPS, to develop a
computer model that predicts the
robot’s location. GPS satellites ping
smartphones and based on how
long it takes for the signal to arrive,
the GPS receiver in the smartphone
can determine where the cellphone
is. Similarly, researchers know how
strong the magnetic field should
be around the magnet embedded
in the robot. They rely on four
sensors carefully spaced around
the area where the robot operates
to measure the magnetic field
strength. Based on how strong the
field is, they are able to determine
where the tip of the robot is.
The system — including the robot,
magnets, and magnet localization
setup — costs around $100.
The team trained a neural network
to learn the difference between
what the sensors were reading and
what the model said the sensors
should be reading. As a result, they
improved localization accuracy
to track the tip of the robot.
Ioana Patringenaru at ipatrin@eng.
ucsd.edu; 619-253-4474.
TECH BRIEFS

Smart Artificial Hand for Amputees
Neuroprosthetic technology combines robotic control with the user’s voluntary control.
École Polytechnique Fédérale de Lausanne, Switzerland
Anew method that improves
control of robotic hands
— in particular, for amputees —
combines individual finger control
and automation for improved
grasping and manipulation. The
technology merges two concepts
from two different fields. One
concept, from neuroengineering,
involves deciphering intended finger
movement from muscular activity on
the amputee’s stump for individual
finger control of the prosthetic hand.
The other, from robotics, allows
the robotic hand to help take hold
of objects and maintain contact
with them for robust grasping.
When humans hold an object
and it starts to slip, there are a
couple of milliseconds to react. The
robotic hand has the ability to react
within 400 milliseconds. Equipped
with pressure sensors along the
fingers, it can react and stabilize
the object before the brain can
perceive that the object is slipping.
The algorithm first learns how to
decode user intention and translates
this into finger movement of the
prosthetic hand. The amputee must
perform a series of hand movements
in order to train the algorithm,
which uses machine learning.
Sensors placed on the ampu
tee’s
stump detect muscular activity and
the algorithm learns which hand
movements correspond to which
patterns of muscular activity. Once
the user’s in
tended finger movements
are understood, this information
can be used to control individual
fingers of the prosthetic hand.
The algorithm was engineered
so that robotic automation kicks
in when the user tries to grasp
an object. The algorithm tells the
prosthetic hand to close its fingers
when an object is in contact with
sensors on the surface of the
prosthetic hand. This automatic
grasping is an adaptation from a
previous study for robotic arms
designed to deduce the shape of
objects and grasp them based on
tactile information alone, without
the help of visual signals.
The shared approach to control
ro
botic hands could be used in
several neuroprosthetic applications
such as bi
onic hand prostheses
and brain-to-machine interfaces.
Watch a video demo of the
technology on Tech Briefs TV at
www.techbriefs.com/tv/smart-hand.
presse@epfl.ch; +41 21 69 3 22 22.
The researcher shares control with the robotic arm. (© 2019 EPFL/Alain Herzog)

Medical-Robotics

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