Rapid microwave annealing of ferroelectric copolymer films for multifunctional perception

Abstract

Multifunctional electronic skins have attracted considerable attention for applications in robotics, health monitoring and human–machine interfaces. Ferroelectric polymers, especially poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)), are one of the most promising materials to construct multifunctional electronic skins due to their exceptional flexibility and piezoelectric and pyroelectric properties. Post annealing treatment is required to enhance crystallization and thus electroactivity of P(VDF-TrFE) films, which usually is both time and energy consuming. Here we developed a rapid microwave annealing (MWA) process which significantly reduced annealing period from several hours to several minutes. AN MWA-treated and 2 μm thick P(VDF-TrFE) film achieved remanent polarization of 0.09C m⁻² and piezoelectric d₃₃ coefficient of 28 pC N⁻¹. MWA-treated copolymer films were further encapsulated by PDMS elastomer for further enhanced d₃₃ coefficient up to 49 pC N⁻¹. This kind of MWA-treated devices were developed for monitoring of human physiological activities, including neck movements, coughing and pulsation, and proximity perception of hot targets for early warning of low-temperature scalds. All these observations indicate that MWA is a feasible and efficient measure to fabricate high-performance ferroelectric copolymer devices for multifunctional perception.