Poling of piezoelectric polymer cables and assessment of their sensor properties

Many sensor and actuator applications were proposed for piezoelectric polymers. Coaxial cables with piezoelectric polymer layers are highly suitable and attractive for a range of these applications. Because of the mechanical stiffness required of such cables, the most common materials for use in sensor cables are nonporous piezoelectric polymers such as polyvinylidene fluoride (PVDF) or its copolymer with trifluoroethylene (P(VDF-TrFE)). Here, we first describe the operating principle and the geometry of piezoelectric polymer cables. As an active piezoelectric layer, P(VDF-TrFE) (76/24) was employed. After electrical poling with one or more point-to-cable corona discharges, we investigated the polarization in the P(VDF-TrFE) layer. Poling parameters such as electric field, poling time and distance between cable and corona needle were varied. The resulting polarization was characterized with measurements of polarization profiles across the layer thickness. The poling process developed here leads to good piezoelectric properties of the cable layer. Finally, discuss the sensor properties of the cable.