This organic electrochemical transistor was made with cotton fibers. The gate, drain and source in the device are made from cotton threads with conductive or semiconductive behavior induced by using nanoparticle-based coatings. |
Smarter,
more functional clothing incorporating electronics may be possible in
the near future, according to a study co-authored by Cornell fiber
scientist Juan Hinestroza.
Hinestroza,
associate professor of fiber science, was part of an international team
that developed transistors using natural cotton fibers.
“Creating
transistors from cotton fibers brings a new perspective to the seamless
integration of electronics and textiles, enabling the creation of
wearable electronic devices,” Hinestroza said.
The
innovation represents a significant step forward because it lays the
groundwork for creating even more complex devices, such as cotton-based
circuits, Hinestroza said. This would allow fabrics to sense body
temperature, automatically heat up or cool down, or track heart rate or
blood pressure in high-risk patients, as well as to monitor physical
effort of high-performance athletes.
“Perhaps
one day we can even build computers out of cotton fibers in a similar
way as khipus—a recording device based on knots and used by the Inca
empire in Peru,” Hinestroza added.
The
research is published online Sept. 13 in Organic Electronics. It
describes a new technique in which conformal coatings—which are those
that follow cotton’s irregular topography—of gold nanoparticles along
with semiconductive and conductive polymers were used to tailor the
electronic behavior of natural cotton fibers.
Cotton
was chosen as a substrate because of its mechanical and inherent
comfort properties, relative cheapness and widespread use in fabric and
clothing. Cotton fibers are lightweight and sustainable.
In
the study, the first step was aimed at creating a conformal layer of
nanoparticles over the rough topography of cotton. The next layers were
either conductive or semiconductive coatings; the final step was to
build the devices.
“The layers were so thin that the flexibility of the cotton fibers was preserved,” Hinestroza said.
Two
kinds of active transistors, organic electrochemical transistors and
organic field effect transistors, were also demonstrated. Both kinds are
widely used in the electronics industry as components of integrated
circuits, which control the functions of such common devices as phones,
televisions and game consoles.
The
study represented an interdisciplinary, collaborative effort between
fiber scientists from Cornell, physicists from the University of Bologna
and electrical engineers from the University of Cagliari, both in
Italy, and materials scientists from the Ecole Nationale Supérieure des
Mines de Saint-Étienne in France.
Hinestroza’s
lab contributed expertise in fibers and fiber functionality, and the
other researchers led with their expertise in physics, electrical
engineering and organic electronics.
The
first author of the paper, Giorgio Mattana of the University of
Cagliari, was at Cornell as an international visiting student for two
semesters in 2009-10 working in Hinestroza’s and another lab on campus.
He also used the facilities of the Cornell Nanofabrication Facility and
Cornell Center for Materials Research.
