Effect of beta-based sterilization on P(VDF-TrFE-CFE) terpolymer for medical applications.

Electroactive polymers (EAP) are one of the latest generations of flexible actuators, enabling new approaches to propulsion and maneuverability. Among them, poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene/chlorotrifluoroethylene), abbreviated terpolymer, with its multifunctional sensing and actuating abilities as well as its impressive electrostrictive behavior, especially when being doped with an plasticizer, has been demonstrated to be a good candidate for the development of low-cost flexible guidewire tip for endovascular surgery. To minimize the possibility of bacterial, fungal, or viral disease transmission, all medical instruments (especially components made from polymers) must be sterilized before introduction into the patient. Gamma/beta (γ/ß) irradiation is considered to be one of the most efficient techniques for targeted reduction of microbials and viruses under low temperature, often without drastic alterations in device properties. However, radiation may cause some physical and chemical changes in polymers. A compromise is required to ensure sufficient radiation for microbial deactivation but minimal radiation to retain the material's properties. The main idea of this study aims at assessing the electromechanical performances and thermal/dielectric properties of ß-irradiated terpolymer-based sterilization treatment. Ionizing ß-rays did not cause any significant risk to the neat/plasticized terpolymers, confirming the reliability of such electrostrictive materials for medical device development.

High-Capacity, Fast-Response, and Photocapacitor-Based Terpolymer Phosphor Composite.

This paper describes a new class of light transducer-based poly (vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) (P(VDF-TrFE-CTFE)) terpolymer doped with 50% wt. phosphor particles that enables to efficiently transform light energy into an electrical signal. Broadband dielectric characterization together with experimental results on photo-electric conversion demonstrated high capacitance variation of the proposed composite under light exposure, confirming promising potential of our sensor device for application in retinal prostheses where the converted electrical signal can affect the biological activity of the neuron system. In addition to the benefit of being light-weight, having ultra-flexibility, and used in a simple process, the proposed photodetector composite leads to fast response and high sensibility in terms of photoelectrical coupling where significant increases in capacitance change of 78% and 25% have been recorded under blue and green light sources, respectively. These results demonstrated high-performance material design where phosphor filler contributes to promote charge-discharge efficiency as well as reduced dielectric loss in P(VDF-TrFE-CTFE), which facilitate the composite for flexible light transducer applications, especially in the medical environment.

Reducing leakage current and dielectric losses of electroactive polymers through electro-annealing for high-voltage actuation.

Electroactive polymers (EAPs) such as P(VDF-TrFE-CTFE) are very promising in the field of flexible sensors and actuators. Their advantages in smart electrical devices are due to their low cost, elastic properties, low density, and ability to be manufactured into various shapes and thicknesses. In earlier years, terpolymer P(VDF-TrFE-CTFE) attracted a lot of research due to its relaxor-ferroelectric property that exhibits high electrostriction phenomena. While widely used in flexible actuation, this class of material is still limited by the high electric fields required (≥30 V µm-1) to achieve sufficient strain levels (>2%). This inevitably leads to high levels of leakage current and thus a short lifetime. This paper proposes a new approach based on electro-annealing thermal treatment for a pure terpolymer P(VDF-TrFE-CTFE) matrix in order to limit the conduction mechanisms. This in turn reduces the dielectric losses at a high level of electric fields. The experimental results demonstrate that a huge decrease in leakage current of 80% is achieved for a wide range of electric fields (i.e. up to 90 V µm-1) with a 4-fold extension in time-to-breakdown at high voltage excitations of 40 V µm-1.