2023 AIChE Annual Meeting

Conductive Polymers As Flexible Sensors

In recent years, a novel class of polymers with intrinsic electrical conductivity, relying on conjugated bonds with delocalized π-electrons along their chains, has emerged1. These organic polymers possess a high band gap that enables electron flow within the material, though they require oxidation or reduction to introduce charge centers in the bandgap. A dopant is used during polymerization to achieve conductivity2.

This study investigates flexible sensors based on polypyrrole doped with different oxidants, ammonium persulfate (APS) and iron chloride (FeCl3), with varying polymerization parameters. The doped polypyrrole is polymerized onto 7cm x 7cm cotton fabric sheets to create flexible eTextiles. Optimal results are obtained using a 1:1 APS : pyrrole mass ratio with a 110-minute polymerization time. The optimized eTextile gave the best range of resistivities from rest to extended fabric, and then rest to compressed fabric. While FeCl3-doped eTextile demonstrates lower resistance, making them better conductors, it lacks the extensive range of resistivity values compared to APS doped eTextiles.

To showcase the properties and sensitivity of the APS-doped polypyrrole eTextile, a fabric origami accordion is constructed using a larger fabric sheet with the same polymerization parameters. This accordion, connected to a Lilypad Arduino™ with a speaker, produces different tones when compressed, reflecting changes in resistivity. The DIY textile sensor's potential applications are demonstrated through this eTextile Origami Accordion, highlighting its use in motion detection and opening doors for future applications, such as motion capture.

References:

1. MacDiarmid, Alan G. "The Nobel Prize in Chemistry, 2000: Conductive polymers."

2. Umoren, S. A., Solomon, M. M., & Saji, V. S. (2022). Conducting polymers. Polymeric Materials in Corrosion Inhibition, 443–466. https://doi.org/10.1016/b978-0-12-823854-7.00002-3