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Tailoring Piezoresistive Sensitivity of Multilayer Carbon Nanotube Composite Strain Sensors
1 Department of Civil & Environmental Engineering, University of Michigan Ann Arbor, MI 48109, USA
* To whom correspondence should be addressed.
In recent years, carbon nanotubes have been utilized for a variety of applications, including nanoelectronics and various types of sensors. In particular, researchers have sought to take advantage of the superior electrical properties of carbon nanotubes for fabricating novel strain sensors. This article presents a single-walled carbon nanotube (SWNT)-polyelectrolyte (PE) composite thin film strain sensor fabricated with a layer-by-layer (LbL) process. Optimization of bulk SWNT-PE strain sensor properties is achieved by varying various LbL fabrication parameters, followed by characterization of strain-sensing electromechanical responses. A resistor and capacitor (RC)-circuit model is proposed and validated with electrical impedance spectroscopy to fit experimental results and to identify equivalent circuit element parameters sensitive to strain. Experimental results suggest consistent trends between SWNT and PE concentrations to strain sensor sensitivities. Simply by adjusting the weight fraction of SWNT solutions and film thickness, strain sensitivities between 0.1 and 1.8 have been achieved. While SWNT-PE strain sensitivity is lower than some metal-foil strain gauges ( Key Words: carbon nanotube composite, electrical impedance spectroscopy, layer-by-layer, nanotechnology, strain sensor.
First published on September 26, 2007, doi:10.1177/1045389X07079872 |
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2), the LbL method allows for precise tailoring of the properties (i.e., strain sensitivity, resistivity, among others) of a high-capacity (±10,000 µm m-1) homogeneous multilayer strain sensor.