Medical Design Briefs - October 2023 - 12

Robot-Assisted Surgery
joystick, guiding the instrument using
visual inputs from
effector-mounted
cameras. Details of the surgical plan may
also be reviewed in real time, allowing
the surgeon to make adjustments based
on the patient's anatomy (e.g., the angle
of a new implant during a hip or knee
replacement procedure).
Thanks to miniaturization and electronics,
RAS effectors are generally
smaller and lighter and often incorporate
multiple functions compared to
their endoscopic predecessors. For example,
while many older surgical instruments
are manufactured in a straightline
configuration - which means they
must bend to reach around obstructions
in surgery - RAS effectors often add
pre-curved or flexible sections that allow
the instrument to bend around
tighter corners. Many of these effectors
are electromechanical, with designs
that incorporate a range of materials,
including metals, elastomers, and
high-performance plastics.
However, the ever-smaller sizes, complex
shapes, and sophisticated electronics,
communications, and controls required
to guide and direct effectors
- along with uncompromising global
standards for medical device safety, reliability,
and quality - pose major manufacturing
and assembly challenges for
medical device manufacturers.
Addressing Assembly Challenges
Fortunately, assembly technologies continue
to evolve as well. For RAS systems
and end effectors that incorporate metal,
elastomeric, and plastic components, ultrasonic
welding remains a core manufacturing
technology. Basically, ultrasonic
welding bonds compatible materials
through a combination of vibratory motion
and compressive force. Mating surfaces
of two parts are compressed together
then subjected to high-frequency oscillation
that creates mechanical friction -
and heat - on those mating surfaces.
In the case of plastics, ultrasonic welding
creates a small, but controlled, melt
area in the weld joint between the two
parts. Recent advances in this process
make it possible not only to control the
time, depth, and power inputs to a weld
but also to regulate downforce so that
parts containing sensors and electronics,
or parts with extremely close tolerance
joints (for example, RAS effectors, cameras,
and related components), can be
12
Today's robot-assisted surgery systems enable surgeons to manipulate effectors, guided by visual inputs from onboard
cameras and sensors. (Credit: Emerson)
Ultrasonic metal and plastic welds are ideal for creating wiring harnesses and connectors used to power and control
robot-assisted surgical equipment. (Credit: Emerson)
welded successfully. Often, ultrasonic
plastic welding is employed for assembling
housings and components that
contain motors, sensors, cameras, valves,
or small-scale tubes that transport and
manage critical fluid or gas flows used in
the surgical procedure.
In the case of nonferrous metals (e.g.,
copper, aluminum, nickel, silver), ultrasonic
welding employs vibration and
compression to create a solid-state molecular
bond between metal parts. The
metallic bond is unique to ultrasonic
metal welding. Another key advantage
of metal welding is the elimination of
health issues associated with soldering
fumes, reducing the need for certified
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Ultrasonic metal welding processes eliminate health
issues associated with soldering fumes, reduce the
need for certified soldering stations, and improve
throughput, quality, and repeatability. (Credit: Emerson)
Medical Design Briefs, October 2023

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Medical Design Briefs - October 2023

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