• Mamishev, Alexander V.
• Sakthivelpathi, Vigneshwar
• Dichiara, Anthony B.
• Li, Tianyi
• Goodman, Sheila M.
• Qian, Zhongjie

Abstract

<jats:title>Abstract</jats:title><jats:p>Auxetic materials showing a negative Poisson’s ratio can offer unusual sensing capabilities due to drastic percolation changes. This study presents the capacitive response of wet-fractured carbon nanotube paper composites in exposure to humidity. A strained composite strip is fractured to produce numerous cantilevers consisting of cellulose fibers coated with carbon nanotubes. During stretching, the thin composite buckles in the out-of-plane direction, which causes auxetic behavior to generate the radially structured electrodes. The crossbar junctions forming among the fractured electrodes significantly increase capacitance and its response to humidity as a function of sensor widths. The molecular junctions switch electric characteristics between predominantly resistive- and capacitive elements. The resulting capacitive response is characterized for humidity sensing without the need for an additional absorption medium. The normalized capacitance change (ΔC/C<jats:sub>0</jats:sub>) exhibits a sensitivity of 0.225 within the range of 40 ∼ 80% relative humidity. The novel auxetic behavior of a water-printed paper-based nanocomposite paves the way for inexpensive humidity and sweat sensors.</jats:p>

Topics

• nanocomposite
• impedance spectroscopy
• Carbon
• nanotube
• forming
• cellulose