Fabrication of a piezoelectric polyvinylidene fluoride/carbonyl iron (PVDF/CI) magnetic composite film towards the magnetic field and deformation bi-sensor

In this paper, a versatile polyvinylidene fluoride/carbonyl iron (PVDF/CI) composite film was prepared by doping magnetic carbonyl iron (CI) particles into piezoelectric polyvinylidene fluoride (PVDF) matrix. Without influencing the piezoelectric structure of PVDF, CI particles enhanced the Young's modulus and maximum tensile strength of composite films. Due to the magnetic driven characteristic, PVDF/CI composite films exhibited distinct magnetic-mechanic-electric coupling properties. The piezoelectric charge signals could be generated by applying the bending deformation or magnetic field. Taking PVDF/CI-10% (CI content was 10 wt%) film as an example, the piezoelectric charges under 2, 4, 6, 8, and 10 mm bending displacement were 3.0, 9.6, 14.9, 18.6, and 24.6 pC respectively. Moreover, when the magnetic field varied from 0 to 600 mT, the generated magneto-electric charges of PVDF/CI-10% film increased from 0 to 676 pC. The quantitative relationship between magnetic field and magneto-electric charges was obtained by the polynomial fitting method and the correlation coefficient was up to 0.97. Owing to the ideal piezoelectricity, excellent stability, light weight and desirable flexibility, PVDF/CI composite films showed promising applications in deformation sensor and magnetic field sensor.