Molten-State Dielectrophoretic Alignment of EVA/BaTiO3 Thermoplastic Composites: Enhancement of Piezo-Smart Sensor for Medical Application

Abstract

Dielectrophoresis has recently been used for developing high performance elastomer-based structured piezoelectric composites. However, no study has yet focused on the development of aligned thermoplastic-based piezocomposites. In this work, highly anisotropic thermoplastic composites, with high piezoelectric sensitivity, are created. Molten-state dielectrophoresis is introduced as an effective manufacturing pathway for the obtaining of an aligned filler structure within a thermoplastic matrix. For this study, Poly(Ethylene-co Vinyl Acetate) (EVA), revealed as a biocompatible polymeric matrix, was combined with barium titanate (BaTiO3) filler, well-known as a lead-free piezoelectric material. The phase inversion method was used to obtain an optimal dispersion of the BaTiO3 within the EVA thermoplastic matrix. The effect of the processing parameters, such as the poling electric field and the filler content, were analyzed via dielectric spectroscopy, piezoelectric characterization, and scanning electron microscopy (SEM). The thermal behavior of the matrix was investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry analysis (DSC). Thermoplastic-based structured composites have numerous appealing advantages, such as recyclability, enhanced piezoelectric activity, encapsulation properties, low manufacturing time, and being light weight, which make the developed composites of great novelty, paving the way for new applications in the medical field, such as integrated sensors adaptable to 3D printing technology.

Haptic Feedback Device Using 3D-Printed Flexible, Multilayered Piezoelectric Coating for In-Car Touchscreen Interface

“…The one with 28 µm corresponded to a single-layered piezo-actuator (as the thickness of each layer is typically around 25–30 µm), while the one with 56 µm was dedicated to a two-layered sample. The screen printing technique allows for an elaboration of very thin film layers, which is otherwise a veritable challenge in the case of conventional methods [ 73 , 84 , 85 ]. On the one hand, reducing the thickness to <25–30 µm for each piezoelectric layer is feasible but time-consuming (even with screen printing technique), since additional processing steps such as etching or polishing are needed.…”

“…To the best of our knowledges, piezoelectric composites have not yet been widely explored in haptic tactile devices. Actually, the performance of these systems strongly depends on several parameters of the fillers (e.g., nature, size, shape, dispersion, and concentration), of the matrix (e.g., dimension, mechanical flexibility, temperature stability, adhesion with substrate, and viscosity), and of the interconnectivity between them (i.e., arrangement of the fillers within the matrix) [ 68 , 69 , 70 , 71 , 72 , 73 , 74 ]. To some extent, these features give multiple possibilities to improve the system performance through adjustments of the materials’ parameters.…”

Investigation of the structure and dielectric properties of doped barium titanates

“… 36 The polarization increase for sample x = 0.75 due to the increase of 180° and 90° domains in the direction of the applied field. 37 The remnant polarization was increased by increasing content up to x = 0.75, indicating that the Zr is a well-selected material for alignment for the domain of BZT samples, 38 suggesting that the studied ferroelectric samples are relaxors ferroelectrics with soft hysteresis loops as shown in Table 9 . At RT, all the present hysteresis loops for samples x = 0, 0.15, and 0.5 show relaxer ferroelectric behavior; 39 these disordered hysteresis loops could be obeying the domain to is the relaxor material up to the applied field.…”

Design Rules of Bidirectional Smart Sensor Coating for Condition Monitoring of Bearings

“…Electronic circuits require very specific functional characteristics, and this continues to be a challenge for printing techniques. In order to overcome this challenge, two different approaches can be distinguished: process engineering, where the currently existing materials are tailored in terms of shape, geometry, and interconnectivity [ 50 , 51 , 52 , 53 , 54 , 55 ], or material engineering, where new materials with tailored functional characteristics for each application are developed [ 56 , 57 , 58 ]. In particular, for ferroelectric materials, the main approach for tailoring electromechanical coupling is to include bulk fillers with large piezoelectric constants into the polymeric matrix [ 59 , 60 , 61 ].…”