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Quasi-static and dynamic strain sensing using carbon nanotube/epoxy nanocomposite thin films

Anand, Sandeep V and Mahapatra, D Roy (2009) Quasi-static and dynamic strain sensing using carbon nanotube/epoxy nanocomposite thin films. In: Smart Materials and Structures, 18 (4).

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Official URL: http://www.iop.org/EJ/abstract/0964-1726/18/4/0450...


Thin films are developed by dispersing carbon black nanoparticles and carbon nanotubes (CNTs) in an epoxy polymer. The films show a large variation in electrical resistance when subjected to quasi-static and dynamic mechanical loading. This phenomenon is attributed to the change in the band-gap of the CNTs due to the applied strain, and also to the change in the volume fraction of the constituent phases in the percolation network. Under quasi-static loading, the films show a nonlinear response. This nonlinearity in the response of the films is primarily attributed to the pre-yield softening of the epoxy polymer. The electrical resistance of the films is found to be strongly dependent on the magnitude and frequency of the applied dynamic strain, induced by a piezoelectric substrate. Interestingly, the resistance variation is found to be a linear function of frequency and dynamic strain. Samples with a small concentration of just 0.57% of CNT show a sensitivity as high as 2.5% MPa-1 for static mechanical loading. A mathematical model based on Bruggeman's effective medium theory is developed to better understand the experimental results. Dynamic mechanical loading experiments reveal a sensitivity as high as 0.007% Hz(-1) at a constant small-amplitude vibration and up to 0.13%/mu-strain at 0-500 Hz vibration. Potential applications of such thin films include highly sensitive strain sensors, accelerometers, artificial neural networks, artificial skin and polymer electronics.

Item Type: Journal Article
Publication: Smart Materials and Structures
Publisher: Institute of Physics and IOP Publishing Limited
Additional Information: Copyright of this article belongs to Institute of Physics and IOP Publishing Ltd.
Department/Centre: Division of Mechanical Sciences > Aerospace Engineering(Formerly Aeronautical Engineering)
Date Deposited: 10 Dec 2009 04:54
Last Modified: 19 Sep 2010 05:29
URI: http://eprints.iisc.ac.in/id/eprint/19718

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