Microfluidic processing of piezoelectric and magnetic responsive electroactive microspheres

Abstract

Poly(vinylidene fluoride) (PVDF) combined with cobalt ferrites particles (CFO) is one of the most common and effective polymeric magnetoelectric composites. Processing PVDF into its electroactive phase is a mandatory condition for featuring electroactive behavior and specific (post)processing may be needed to achieve this state. However, by processing at a temperature below 60 ºC, electroactive phase crystallization is favored. Besides, different experimental techniques are used to process various forms of PVDF-CFO nanocomposites structures being aware that high CFO dispersion must be achieved. Microfluidics offers the possibility of processing PVDF-CFO microspheres with high reproducibility, size tunability, and time and resources efficiency. Moreover, magnetoelectric microspheres are produced in a one-step approach. Thus, the present work describes the production of high content electroactive phase PVDF and PVDF-CFO microspheres using microfluidic technology. A flow-focusing polydimethylsiloxane (PDMS) device is fabricated based on a 3D printed polylactic acid (PLA) master. The device enables the production of spherical microspheres with mean diameters ranging from 80 and 330 µm depending on the continuous/discontinuous feeding ratio. The microspheres feature internal and external cavernous structures and good CFO distribution with an encapsulation efficacy of 80%. Moreover, the microspheres prove to be in the electroactive γ-phase with a mean content of 75%. Thus, the prepared microspheres show suitable characteristics as active materials for tissue regeneration strategies.