Smarter, more functional clothing made with wearable electronics may be possible in the near future.
The innovation represents a significant step forward because it lays the groundwork for creating even more complex devices, such as cotton-based circuits, Hinestroza says.
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 adds.
The research is published 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.
The first step for researchers was to create 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 says.
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 was a 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.