Multifunctional Carbon Nanotube Yarn Sensors
Macro-scale Carbon Nanotube Devices
Multifunctional Strain and Temperature Sensing
- It is our vision that the future of advanced aerospace vehicles and structures is dependent upon successful technological advances and economical advantages that address high-level requirements such as light weight and small volume, low power consumption, and higher performance of components and subsystems. The use of novel nano-structured materials offers the promise to directly address these challenges and provide the foundation for advances in multifunctional materials in NASA’s vision for the future of advanced aerospace vehicles and space structures. Often, these features translate into a challenge of 1) designing multifunctional structures with materials that exhibit an array of distinct mechanical/thermal/electrical properties and also 2) ensuring the reliability and durability of the final structural components.
- In contrast to single-walled and multi-walled carbon nanotubes with lengths of only micrometers, Multiwalled Carbon Nanotube (MWCNT) yarns are available in lengths of 100 meters. When embedded in polymers, they would form the basis for a CNT yarn/carbon fiber composite structure providing local and/or global measurements of strain and temperature.
- The single yarn can be spun into multiple plies, and four figures shown below are: single yarn, 36-ply yarn, a hybrid glass fiber 3-D braid with CNT yarns visible as dark lines (middle picture), and a 3-D woven fabric with 25-ply CNT yarns incorporated as the first five Z-yarns from the bottom (right figure). (Courtesy of University of Texas at Dallas and 3TEX Inc in Cary, NC.) As a team, NASA Langley Research Center, University of Texas, and 3TEX, is developing a carbon fiber base structure with imbedded MWCNT multifunctional sensors.
- Multifunctional sensing characteristics and mechanical behavior for both CNT yarn itself and CNT yarn composites have been established at NASA Langley . Figure 1-a shows strain response of CNT 2-ply yarn when it is used as a quarter bridge configuration on a stainless steel test beam. Figure 1-b shows resistance of CNT yarns as the temperature is varied from -30C to +90C; the temperature coefficient of resistance (TCR) of the yarns embedded in polyurethane (CF-95) on an aluminum substrate is -0.14 Ohms/Degree Celsius, this trend is indicated by a double headed arrow.
Figure 1. Figure 1-a shows a normalized output from Wheatstone bridge with CNT yarn as a quarter bridge element on a strain test beam (left side graph). Figure1-b is a temperature profile of 18 CNT yarns with a temperature sensor and reference resistor (right side graph). The trend of TCR is shown with double headed arrow.
- Kahng et al, “Multifunctional Characteristics of Carbon Nanotube (CNT) Yarn Composites,” ASME, Multifunctional Nanocomposites 2006, September 2006, Honolulu, Hawaii, MN2006-17028
- Kahng et al, ASME CANEUS, Micro- and Nano-Technology Applications, Toulouse, France, August, 2006
- Jefferson, Gail D., T.S. Gates, S. Kahng, “Mechanical Performance of Multiscale Multi-Walled Carbon Nanotube Twisted Yarns,” SAMPE Annual Technical Conference, Cincinnati, OH, October 2007.
- Gates, Thomas S., G.D. Jefferson, S.J.V. Frankland, “Multiscale Analysis as Applied to Multi-walled Carbon Nanotobe Twisted Yarns,” SAMPE Annual Technical Conference, Cincinnati, OH, November 2007.