Dielectrophoretically Assembled Polymer Nanowires for Gas Sensing

TL;DR

This paper demonstrates the dielectrophoretic assembly of PEDOT/PSS nanowires with striped gold segments for gas sensing, showing rapid, reproducible responses to acetone, methanol, and ethanol vapors, suitable for electronic nose applications.

Contribution

It introduces a novel dielectrophoretic assembly method for striped polymer nanowires and evaluates their effectiveness as gas sensors.

Findings

Nanowires exhibit a conductivity of 11.5 S/cm.

Resistance changes by up to 10.5% for acetone vapor.

Sensors respond and recover within seconds with high reproducibility.

Abstract

We measured the electronic properties and gas sensing response of nanowires containing segments of poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT/PSS) that were synthesized using anodic aluminum oxide (AAO) membranes. The nanowires have a "striped" structure of gold-PEDOT/PSS-gold and are typically 8 um long (1 um-6 um-1 um for each section, respectively) and 220 nm in diameter. Dielectrophoretic assembly was used to position single nanowires on pre-fabricated gold electrodes. A polymer conductivity of 11.5 +/- 0.7 S/cm and a contact resistance of 27.6 +/- 4 kOhm were inferred from resistance measurements of nanowires of varying length and diameter. When used as gas sensors, the wires showed a resistance change of 10.5%, 9%, and 4% at the saturation vapor pressure of acetone, methanol and ethanol, respectively. Sensor response and recovery were rapid (seconds) with excellent reproducibility in time and across devices. "Striped" template-grown nanowires are thus intriguing candidates for use in electronic nose vapor sensing systems.