Tech Briefs Magazine - January 2022 - 35

Materials & Coatings
Programmable Digital Fiber
The fiber contains memory, temperature sensors, and a trained neural network program for
inferring physical activity.
Massachusetts Institute of Technology, Cambridge
esearchers have created a fiber with
digital capabilities that is able to sense,
store, analyze, and infer activity after being
sewn into a shirt. Digital fabrics uncover
the context of hidden patterns in the
human body that could be used for physical
performance monitoring, medical
inference, and early disease detection.
Until now, electronic fibers have been
analog - carrying a continuous electrical
signal - rather than digital, where discrete
bits of information can be encoded
and processed in 0s and 1s. The new fabR
ric
stores and processes data digitally,
adding a new information content
dimension to textiles and allowing fabrics
to be programmed.
The new fiber was created by placing
hundreds of square silicon microscale digital
chips into a preform that was then
used to create a polymer fiber. By precisely
controlling the polymer flow, the
researchers were able to create a fiber
with continuous electrical connection
between the chips over a length of tens of
meters. The fiber itself is thin and flexible
Researchers created the first fabric fiber to have digital capabilities and is ready to collect, store,
and analyze data using a neural network. (Image: Anna Gitelson-Kahn; photo by Roni Cnaani)
and can be passed through a needle, sewn
into fabrics, and washed at least 10 times
without breaking down.
A digital fiber offers a way to control
individual elements within a fiber,
from one point at the fiber's end. The
researchers devised a digital addressing
method that allows them to " switch on "
the functionality of one element without
turning on all the elements.
A digital fiber can also store a lot of
information in memory. The researchers
were able to write, store, and read information
on the fiber including a 767-kilobit
full-color short movie file and a 0.48megabyte
music file. The files can be
stored for two months without power.
The fiber also takes a few steps forward
into artificial intelligence by including,
within the fiber memory, a neural network
of 1,650 connections. After sewing it
around the armpit of a shirt, the
researchers used the fiber to collect 270
minutes of surface body temperature data
from a person wearing the shirt and analyzed
how these data corresponded to different
physical activities. Trained on these
data, the fiber was able to determine with
96 percent accuracy what activity the person
wearing it was engaged in.
Adding an AI component to the fiber
further increases its possibilities. Fabrics
with digital components can collect
information across the body over time,
and these lush data are perfect for
machine learning algorithms. This type
of fabric could give quantity and quality
open-source data for extracting out new
body patterns.
A close-up of the digital fibers on green fabric. (Image: Anna Gitelson-Kahn; photo by Roni Cnaani)
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With this analytic power, the fibers
someday could sense and alert people in
real time to health changes like a respiratory
decline or an irregular heartbeat, or
deliver muscle activation or heart rate
data to athletes during training. The
fiber is controlled by a small external
device, so the next step will be to design
a new chip as a microcontroller that can
be connected within the fiber itself.
For more information, contact Abby
Abazorius at abbya@mit.edu; 617-253-2709.
35

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