Carbon nanotube forests can be drawn into a web and further twisted into yarns. These yarns have relatively high mechanical, thermal and electrical properties and also exhibit piezo impedance that could be used for sensing purposes. Three students in Abot’s research group, Tareq Alosh, Angeline Bajar and Erica Good, studied experimentally the mechanical and electrical response of carbon nanotube yarns consisting of 1 to 3 threads. A state-of-the-art mechanical loading system with especially designed fixtures were used to acquire the mechanical data. Additionally, an Inductance-Capacitance-Resistance reader was used to continuously measure the resistance utilizing a four probe method. In the framework of his Master of Science research studies, Tareq was able to determine this coupled response and he unveiled a not-yet observed phenomenon: a parabolic negative piezoresistive response. Additionally, he observed and measured an increase in resistance towards the end of the tension loading. In the framework of a NASA summer grant, Angeline and Erica, made further progress on the understanding of this response. This observed negative piezoresistance in carbon nanotube yarns could play a significant role in many engineering applications, most notably in sensors. More details about this research can be found in the publications mentioned in Abot’s personal webpage.
Angeline & Erica presented their findings at the SHPE Conference in Indianapolis, Indiana.