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NANOENGINEERED INDUCTIVELY COUPLED CARBON NANOTUBE WIRELESS STRAIN SENSOR

K. J. Loh, J. P. Lynch, and N.A. Kotov
Department of Civil & Environmental Engineering, University of Michigan, Ann Arbor, MI 48109 USA

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Abstract
Since the discovery of carbon nanotubes by Iijima in 1991, researchers have utilized carbon nanotubes for a wide array of applications including nanoelectronics, sensors, and inductively coupled antennas. While current and novel strain transducers can measure strain adequately, their large form factor and cabled data acquisition systems render their use in harsh environments difficult. It has been demonstrated from early experimental studies that conformable carbon nanotube/polyelectrolyte thin films exhibit linear changes in resistivity with applied strain. By patterning these films into coil antenna patterns, a passive inductively coupled wireless strain sensor is fabricated and presented. Antenna resonant frequency and bandwidth is characterized, and the overall response represents that of a series RLC resonant circuit. It is shown that the wireless nanotube strain sensor shows corresponding changes in bandwidth to applied strain. To optimize the performance of the carbon nanotube composite antenna, electrochemical impedance spectroscopy is employed to fully characterize the bulk electrical properties of the carbon nanotube/polyelectrolyte thin films.