Abstract
This research paper is concentrated on the design of biologically compatible lead-free piezoelectric composites which may eventually replace traditional lead zirconium titanate (PZT) in micromechanical fluidics, the predominantly used ferroelectric material today. Thus, a lead-free barium–calcium zirconate titanate (BCZT) composite was synthesized, its crystalline structure and size, surface morphology, chemical, and piezoelectric properties were analyzed, together with the investigations done in variation of composite thin film thickness and its effect on the element properties. Four elements with different thicknesses of BCZT layers were fabricated and investigated in order to design a functional acoustophoresis micromechanical fluidic element, based on bulk acoustic generation for particle control technologies. Main methods used in this research were as follows: FTIR and XRD for evaluation of chemical and phase composition; SEM—for surface morphology; wettability measurements were used for surface free energy evaluation; a laser triangular sensing system—for evaluation of piezoelectric properties. XRD results allowed calculating the average crystallite size, which was 65.68 Å3 confirming the formation of BCZT nanoparticles. SEM micrographs results showed that BCZT thin films have some porosities on the surface with grain size ranging from 0.2 to 7.2 µm. Measurements of wettability showed that thin film surfaces are partially wetting and hydrophilic, with high degree of wettability and strong solid/liquid interactions for liquids. The critical surface tension was calculated in the range from 20.05 to 27.20 mN/m. Finally, investigations of piezoelectric properties showed significant results of lead-free piezoelectric composite, i.e., under 5 N force impulse thin films generated from 76 mV up to 782 mV voltages. Moreover, an experimental analysis showed that a designed lead-free BCZT element creates bulk acoustic waves and allows manipulating bio particles in this fluidic system.
Highlights
A copper plate here acts as a bottom electrode, a nickel thin film layer of 10 nm formed on the barium–calcium zirconate titanate (BCZT) layer acts as a top electrode
The designed lead-free BCZT based microfluidic device for controlled particle flow manipulation based on bulk acoustic waves (BAW) offers significant benefits for fluid handling instruments in pharmaceutical and biochemical research, laboratory diagnostics, etc
Designed lead-free BCZT composite material was successfully investigated and implemented in the design of BCZT based elements used for microchannels for acoustic droplet handling systems
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Passive techniques are based on hydrodynamic particle manipulation by tuning geometry and fluid; active ones—by acoustic manipulation Both are widely applied, discussed, and examined; they have certain limitations such as poor separation efficiency for particle-rich analytes or fluids, and particle size (typical range from 1 to 20 μm), thermal stresses in material during the flow process which may destructs particles, etc. Designed lead-free BCZT based microchannel creates multidimensional bulk acoustic waves and propels the particles towards the channel allowing to control the migration and concentration of particles’ kinetics. This feature is desirable in such microsystem devices where scalability, programmability, and the ability to control variable size particles is crucial
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