Aligning polymer fibers to improve organic piezoelectric performance

Piezoelectric materials, which generate electricity under mechanical deformation, need to be flexible, lightweight, and lead-free for wearable and biomedical applications. While inorganic options exhibit excellent piezoelectric properties, they are brittle and often contain lead. In contrast, organic polymers are biocompatible but suffer from low piezoelectric performance.

To address this issue, Kim et al. proposed a method to promote the crystalline β phase content in poly(vinylidene fluoride-co-trifluoroethylene), which is responsible for its piezoelectric properties. Their technique aligns polymer fibers via electrospinning.

The setup consisted of a high voltage supply, needle and syringe, and a collector. The collector was shaped as either a cylinder-like drum or a disc and was rotated while polymer fibers were deposited on top of it and coiled around it. By increasing the rotation speed, the group induced an airflow that deposited the fibers onto the collector in a highly aligned manner.

“High linear speed of the collector induced stronger airflow around the surface of the collector, which can lead to the high alignment of electrospun fibers,” said author Miso Kim. “In addition to that, our study reveals that higher crystallinity and β phase content were achieved during the alignment due to the airflow.”

Both the drum and disc collectors yielded enhanced piezoelectric performance at high rotation speeds. However, the drum collector is more advantageous for creating fiber mats with large areas.

“Our ongoing work is combining chemical doping and high alignment of fibers, so that we can obtain further enhanced piezoelectric performance,” said Kim. “In parallel, we put our efforts into finding novel self-powered applications that can be used more practically and commercially.”

Source: “Airflow-induced P(VDF-TrFE) fiber arrays for enhanced piezoelectric energy harvesting,” by Yong-Il Kim, Dabin Kim, Jihun Jung, Sang-Woo Kim, and Miso Kim, APL Materials (2022). The article can be accessed at https://doi.org/10.1063/5.0081257 .