Tech Briefs Magazine - October 2021 - MD-21

The researchers cut resonators into rectangular acrylic plates
to determine what might happen if resonators were cut directly
into a material, rather than added on later. The study did not
directly compare cut-in resonators to those that are added on.
Cut-in resonators are more streamlined than those that are
added on and would be better options for applications where
space matters - in the construction of an airplane or a wall,
for example.
The researchers held the plates in place using different
mechanisms - some were clamped tightly, some were suspended
in air, and some were held up by supports. Then they
used a mechanized hammer to strike the plates and measured
the force of the vibrations created by each plate after the hammer's
impact. They kept one plate unaltered as a control.
They found that vibrations traveled farther on the unaltered
plates than on those with built-in resonators. The resonators,
their experiments showed, helped the plates flex and absorb
the vibrations from the hammer.
The experiments were built to test a design that could have
multiple real-world applications and could be used to soundproof
walls. It also could be used to build airplane frames that
automatically lessen the sound that enters the cabin; for
example, a sandwich-like construction consisting of a lightweight
panel with a built-in resonator between two panels of
sheetrock or layered inside the walls of an airplane. This
could be used to reduce vibration of the entire system without
reducing the aerodynamics or efficiency since mass is
eliminated.
The resonators also were able to absorb vibrations regardless
of how the plates were held in place.
For more information, contact Laura Arenschield of OSU at
arenschield.2@osu.edu.
Liquid Metal Sensors and AI Help Prosthetic Hands
" Feel "
The technology could improve the control of prosthetic hands and provide a sense of " touch "
for amputees.
Florida Atlantic University, Boca Raton
Each human fingertip has more than 3,000 touch receptors
that largely respond to pressure. Humans rely heavily on
sensation in their fingertips when manipulating an object, so
the lack of this sensation presents a unique challenge for individuals
with upper limb amputations. While there are several
dexterous prosthetics available today, they all lack the sensation
of " touch. " The absence of this sensory feedback results in
objects inadvertently being dropped or crushed by a prosthetic
hand.
To enable a more natural feeling prosthetic hand interface,
researchers incorporated stretchable tactile sensors using liquid
metal on the fingertips of a prosthetic hand. Encapsulated
within silicone-based elastomers, this technology provides key
advantages over traditional sensors including high conductivity,
compliance, flexibility, and stretchability. This hierarchical
multi-finger tactile sensation integration could provide a higher
level of intelligence for artificial hands.
The researchers used individual fingertips on the prosthesis
to distinguish between different speeds of a sliding motion
along different textured surfaces. The four different textures
had one variable parameter: the distance between the ridges.
To detect the textures and speeds, researchers trained four
machine learning algorithms. For each of the ten surfaces, 20
trials were collected to test the ability of the machine learning
algorithms to distinguish among the ten different complex surfaces
comprised of randomly generated permutations of four
different textures.
Results showed that the integration of tactile information
from liquid metal sensors on four prosthetic hand fingertips
simultaneously distinguished among complex, multi-textured
surfaces, demonstrating a new form of hierarchical intelliMotion
Design, October 2021
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Tech Briefs Magazine - October 2021

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