Specialty Fabrics Review August 2019 - 82

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ADVANCED TEXTILES

The Wearable Technology Laboratory
at the University of Minnesota has
been doing research recently in the
use of integrated active materials,
particularly shape memory materials,
used in soft robotics. Photo: UMN
Wearable Technology Lab.

Soft robotics
Shape memory alloys are a fit with textile technologies.
BY JANET PREUS

Legging prototype
The University of Minnesota's Wearable
Technology Lab has been working on
new compression garments that can
be customized for each wearer and
circumstance, and can be controlled
remotely. Photo: UMN Wearable
Technology Lab.

82 REVIEW AUGUST 2019

hat makes a material robotic? According to Brad Holschuh, Ph.D., assistant
professor of wearable technology and apparel design in the College of Design at the
University of Minnesota (UMN), the simplest explanation is that it's a synthetic
product with mechanical actuation that can move or complete actions independent of, or in
partnership with, humans.
"Soft roboticists say the true defining feature is mechanical capability-the ability to
create movement, force, displacement, torque, pressure, stroke-all the hallmarks of a typical
mechanical system, but using materials that are nonrigid," he says.
At IFAI's 2019 Smart Fabrics Virtual Summit, Holschuh, who co-directs the UMN Wearable
Technology Laboratory (WTL), gave a presentation titled "Soft-Robotic Textiles Using Integrated
Active Materials." He noted the many materials and their capabilities that can be useful in
soft robotic applications, particularly in shape memory functions. Holschuh says that because
shape memory alloys (SMAs) "can change shape, and the change can be controlled in a way
that is reliable and repeatable," they can be useful in a variety of applications and markets.
One application is in compression garments, which are widely used and have been
around for quite a while. "But I've never met a single person that says they enjoy wearing
a compression garment that's on the market," Holschuh says. "The two biggest complaints
are that they're really hard to put on, and once they're on, they squeeze you all the time." It's
also "a relatively simplistic therapy. It's not dynamic; it's just there."
Problems with existing compression garments are exacerbated when used by people who
are infirm or have difficulty putting on and taking off the garment. "The alternative is a
pneumatic technology," he says, "which can offer a degree of controllability, but pneumatic
compression garments usually require that the person is stationary."
ON-BODY ACTUATION
Holschuh's work has moved beyond both types and incorporates on-body actuation. "What
we designed is compression garments that give you the control of a pneumatic, but give you
the form factor that's much more in line with what you can wear in your everyday life." In
order to do that, Holschuh and his team had to address two main issues with SMAs: they
take a lot of power, and they generate heat-too much heat.
His team has been able to bring temperature thresholds down and close to body temperature,
so that simple contact with the body will activate the function, "or a little higher than body

Specialty Fabrics Review August 2019

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