Dispersion of LiZnTiBi ferrite particles into PMDS film for miniaturized flexible antenna application

Abstract

In this work, LiZnTiBi ferrites with high permeability (∼142@1 MHz, ∼13@1 GHz) over a wide frequency range were synthesized at low temperature. Next, the ultrafine ferrite particles were obtained by grinding, centrifugation and ultrasonic method. The flexible PDMS-based film was prepared by dispersing the ferrite particles into PDMS film by a fast curing method. The high frequency magnetic and dielectric properties of the flexible films with various ferrite particles were investigated. Results demonstrated that effect of ferrite particles on permittivity (ε′) can be weakened by residual air bubbles in the flexible film, which leads to measured value lower than calculated value. Due to same permeability (μ′= 1) of PDMS and air bubbles, the residual bubbles have a little effect on permeability of flexible film. At last, a flexible PDMS-based film with desirable normalized characteristic impedance (Z/Z0 = 0.95η0) and miniaturization factor (n = 5.26) at 100 MHz was obtained, which can be applied to miniaturized flexible antenna. Moreover, the strategy that introducing magnetic particles and a small amount of pores into flexible film to adjust magnetic-dielectric properties is also a reference for developing other high-frequency materials for flexible electronics, especially for wearable electronics.