Applications for electroactive polymer films

Abstract

The discovery of PVDF’s inherent piezoelectric qualities lead to diversification of electroactive polymers. Furthermore, applications for PVDF-based polymers now include actuators, energy harvesters, pumps, switches, and biomedical scaffolds. Here, P(VDF-TrFE-CFE) and P(VDF-TrFE), are applied for use as multilayer actuators and osteoconductive coatings respectively.

The multi-layer actuator study focused on creating micro-scale, transferable, array structures

P(VDF-TrFE-CFE) was chosen for its large displacement under stimulation by electric field. This research examined following actuator manufacturing techniques: coating of substrate with polyimide, lamination to produce multiple layers, creation of a barrier layer to protect the polymer layers from the photoresist solvent, and reactive ion etching. A unit device was also created to test the multi-layer fabrication technique’s functionality. From these studies, it was determined that polydopamine can increase the adhesion of polyimide on glass and a new form of adhesion mediated film transfer can create multilayer structures. A set of polymers were determined to be resistant to the SU-8 developer, and a PI/PVP mixture was chosen as an appropriate barrier layer. Etching rates of P(VDF-TrFE-CFE) are given. These techniques increase the ease of fabricating and patterning multilayer polymer structures.

Cells are driven by electrical signals and subsequently, piezoelectric materials increase the speed of bone regrowth. P(VDF-TrFE) was studied in conjunction with a common biomedical implant coating, hydroxyapatite. The hydroxyapatite was first coated with polydopamine to increase the bonding between the polymer and the ceramic. Streptococcus mutans was grown on the surface of the implants to determine how surface roughness affected the bacteria growth. Our results show that the bacteria growth was inhibited by the addition of HAp particles into the membrane. Furthermore, the addition of a filler increased the crystallinity of the P(VDF-TrFE) membranes, and the cells grew better on polarized samples. With this technology, implants with increased osteoconductive properties can be manufactured.