Tech Briefs Magazine - March 2021 - 34

Electrical/Electronics
push-in wiring for tool-free connectivity and long-term vibration resistance
(Figure 2).
Users will find it most convenient if
the I/O system can be pre-configured
on the workbench with simple software

and a standard micro-USB cable. Once
installed, LED status lights and marking
provisions should be provided to help
users commission and maintain the I/O.
Choosing the right standardized remote
I/O platform simplifies the task of auto-

mating equipment and creating IIoT
applications, and provides seamless connectivity between almost any type of field
devices and controllers.
For more information, visit http://info.
hotims.com/79411-122.

Sensor Material Enables Stretchable Electronics to
Perform Better Under Strain
The stretchable electronics are more stable as they change shape, which could lead to
next-generation sensors for healthcare applications.
University of Chicago, Illinois

ur bodies send out hosts of signals
- chemicals, electrical pulses, mechanical shifts - that can provide a
wealth of information about our health.
But electronic sensors that can detect
these signals are often made of brittle,
inorganic material that prevents them
from stretching and bending on the
skin or within the body. Recent advances have made stretchable sensors
possible but their changes in shape can
affect the data produced and many sensors cannot collect and process the
body's faintest signals.
A new sensor design incorporates a patterned material that optimizes strain distribution among transistors, creating
stretchable electronics that are less compromised by deformation. The researchers also created several circuit elements
with the design, which could lead to even
more types of stretchable electronics.
To design the electronics, the researchers used a patterned strain-distribution concept. When creating the transistor, they used substrates made of elastomer - an elastic polymer. They varied
the density of the elastomer layers,
meaning some remained softer while
others were stiffer while still elastic. The
stiffer layers - termed " elastiff " by the
researchers - were used for the active
electronic areas.
The result was transistor arrays that
had nearly the same electrical performance when they were stretched and
bent as when they were undeformed. In
fact, they had less than five percent performance variation when stretched with
up to 100 percent strain. The team also
used the concept to design and fabricate
other circuit parts including NOR gates,
ring oscillators, and amplifiers. NOR
gates are used in digital circuits, while
ring oscillators are used in radio-fre-

The design makes stretchable electronics more stable as they change shape. (Photo courtesy of
Wang Group)

quency identification (RFID) technology. By making these parts successfully
stretchable, the researchers could make
even more complex electronics.
The stretchable amplifier they developed is among the first skin-like circuit
that is capable of amplifying weak electrophysiological signals - down to a few
millivolts. That's important for sensing
the body's weakest signals like those from
muscles. The signals can be processed
and amplified directly on the skin.

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The design is being assessed as a diagnostic tool for ALS. By measuring signals from muscles, the researchers hope
to better diagnose the disease while
gaining knowledge about how the disease affects the body. They also hope to
test the design in electronics that can be
implanted within the body and to create
sensors for all kinds of bodily signals.
For more information, contact Devon
McPhee at dmcphee@uchicago.edu; 773834-5064.
Tech Briefs, March 2021

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Tech Briefs Magazine - March 2021

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