Medical Design Briefs - June 2022 - 24

n Toward Closed-Loop Systems
Looking to the future, penetrating microneedle
arrays with large spatial coverage
will be needed to improve brain-machine
interfaces to the point that they can be
used in " closed-loop systems " that can help
individuals with severely limited mobility.
For example, this kind of closed-loop system
might offer a person using a robotic
hand real-time tactical feedback on the objects
the robotic hand is grasping.
Tactile sensors on the robotic hand
would sense the hardness, texture, and
weight of an object. This information recorded
by the sensors would be translated
into electrical stimulation patterns which
travel through wires outside the body to
the brain-computer interface with penetrating
microneedles. These electrical signals
would provide information directly to
the person's brain about the hardness,
texture, and weight of the object. In turn,
the person would adjust their grasp
strength based on sensed information directly
from the robotic arm.
This is just one example of the kind of
closed-loop system that could be possible
once penetrating microneedle arrays
can be made larger to conform to the
brain and coordinate activity across the
" command " and " feedback " centers of
the brain.
Previously, the Dayeh laboratory invented
and demonstrated the kinds of tactile
sensors that would be needed for this kind
of application, as highlighted in this video.
n Pathway to Commercialization
The advanced dual-side lithographic
microfabrication processes described in
the paper are patented (US 10856764).
Dayeh co-founded Precision Neurotek
Inc. to translate technologies innovated in
his laboratory to advance state of the art in
clinical practice and to advance the fields
of neuroscience and neurophysiology.
The paper, " Scalable Thousand Channel
Penetrating Microneedle Arrays on
Flex for Multimodal and Large Area
Coverage BrainMachine Interfaces, " was
published online in the journal Advanced
Functional Materials. This work is led by a
team in the lab of electrical engineering
professor Shadi Dayeh at the University
of California San Diego, together with
researchers at Boston University led by
biomedical engineering professor Anna
Devor.
For more information, visit https://
jacobsschool.ucsd.edu.
New 3D Printing Technique: A Game Changer for
Medical Testing Devices
The technique fabricates
microfluidics for
biomedical applications at
a microscale not
previously possible.
University of Southern California
Los Angeles, CA
Microfluidic devices are compact testing
tools made up of tiny channels carved
on a chip, which allow biomedical researchers
to test the properties of liquids,
particles, and cells at a microscale. They
are crucial to drug development, diagnostic
testing, and medical research in
areas such as cancer, diabetes and now
COVID-19. However, the production of
these devices is very labor intensive, with
minute channels and wells that often
need to be manually etched or molded
into a transparent resin chip for testing.
While 3D printing has offered many advantages
for biomedical device manufacturing,
its techniques were previously not
sensitive enough to build layers with the
minute detail required for microfluidic
devices. Until now.
Researchers at the USC Viterbi
School of Engineering have now developed
a highly specialized 3D printing
technique
that
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MDB Tech Briefs 0622_1.indd 24
allows
microfluidic
y
Z
X
y
Z
X
3 mm
An example of a microfluidic chip created by the research team. (Credit: Yang Xu)
channels to be fabricated on chips at a
precise microscale not previously
achieved. The research, led by Daniel J.
Epstein; department of industrial and
systems engineering PhD graduate
Yang Xu; and professor of aerospace
and mechanical engineering and industrial
and systems engineering Yong
Chen; in collaboration with professor of
chemical engineering and materials science
Noah Malmstadt and professor
Huachao Mao at Purdue University, was
www.medicaldesignbriefs.com
ToC
5/25/22 2:50 PM
published in Nature Communications.
The research team used a type of 3D
printing technology known as vat
photo polymerization, which harnesses
light to control the conversion of liquid
resin material into its solid end state.
" After light projection, we can basically
decide where to build the parts (of
the chip), and because we use light, the
resolution can be rather high within a
layer. However, the resolution is much
worse between layers, which is a critical
Medical Design Briefs, June 2022
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Medical Design Briefs - June 2022

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