Thermoformed tubular channels piezoelectrets exhibiting piezoelectric-magnetic behaviors were recently presented as Thermoformed Magnetic-Piezoelectrets (TMPs). This alternative sensor was suitable for detecting external magnetic fields from distant magnets. In this contribution, TMPs transducer was investigated as current transducer, where the magnetic field produced by an electrical current passing through a energized wire mechanically stimulates the TMP and consequently disrupts the electrical charge equilibrium providing a proportional electrical signal. The charge variation was correlated with the magnetic field intensity, providing a piezo-magnetic coefficient, similar to those noted in traditional piezoelectrets. It has been noticed that under certain conditions, TMP could have coefficients up to 498 × 10 ⁵ pC/T. From these results, it was concluded that such a polymer-based device is suitable for monitoring electrical current in live wires, providing an interesting solution for non-invasive current transducers (CT) with a reduced footprint. These novel transducers can thus provide an effective replacement for coil-based CTs reducing installation cost and space, without the need for wire re-connection (as required by the coil CTs), enabling hot-plug capabilities, as well as providing a direct and cost-effective replacement for high-frequency current transformers.

This study explores the vibrational behavior of Thermoformed Magneto-Piezoelectrets (TMPs), multifunctional materials consisting of thermoformed piezoelectrets with open tubular channels integrated with an additional magnetic layer. The inverse piezoelectric effect was characterized using laser vibrometry analysis, measuring the mechanical response of TMPs subjected to electrical excitation over a frequency range of 0–20 kHz. Vibrational analysis was conducted at 144 spatial points, enabling the construction of detailed three-dimensional (3D) maps of the vibration operational modes and the spatial distribution of the piezoelectric coefficient ($d_{33}$). The results demonstrated significant frequency-dependent behavior, with open channels exhibiting pronounced resonance peaks, whereas valleys displayed smoother and more uniform responses due to enhanced damping effects. The observed heterogeneity in vibrational behavior is attributed to structural variations, material composition, and anisotropic coupling between the piezoelectric and magnetic properties. The findings presented in this research provide a comprehensive understanding of the development and utilization of TMPs, offering parameters for enhancing their application and supporting new discoveries in studies related to the fabrication of novel thermoformed piezoelectric sensors.

Ensuring proper shielding is essential for the electromagnetic compatibility of electronic devices and systems. This article investigates the shielding effectiveness of coaxial cables and connectors using an electric field probe. The study aims to identify shielding failures early to prevent costly fixes later. A method for measuring the electric field radiated by connectors and cables in both near-field and far-field conditions is presented. Additionally, an electromagnetic virtual model of the connector and cable was developed, incorporating the dimensions and properties of the dielectric material. The simulations focused on the impact of different dielectrics on the resonant frequency of the electric field, specifically common-mode energy. The results showed that the dielectric properties do not affect the resonant frequency in the presence of a common-mode current distribution.

The reuse of industrial residues has gained importance due to environmental and public health concerns associated with improper waste disposal. Steel scale (CDA), a by-product of machining and rolling operations, represents a residue with technological potential for incorporation into polymer composites. This study developed a low-cost and sustainable material by reinforcing an orthophthalic polyester matrix with CDA and systematically evaluated its mechanical, thermal, and structural properties. Four formulations were prepared based on the maximum feasible filler loading: R (pure resin), C1 (50% CDA), C2 (100% CDA), and C3 (150% CDA). Composites were manufactured by cold-press molding under a two-ton compressive load. Characterization included tensile, flexural, and impact testing, thermogravimetric analysis (TGA), thermal conductivity, apparent density, liquid absorption, and morphological assessment by scanning electron microscopy (SEM). CDA incorporation reduced tensile and flexural strength but increased elastic modulus, impact toughness, and thermal conductivity. The C3 composite exhibited the highest thermal stability, retaining more than 50% of its initial mass at 500 °C. Density and liquid absorption increased proportionally with filler loading, and SEM revealed heterogeneous microstructures with particle agglomeration, sedimentation, and interfacial gaps, explaining the mechanical and thermal trends. The findings demonstrate the feasibility of producing dense and low-cost polyester composites reinforced with steel scale. The structure–property relationships identified in this study establish a foundation for subsequent investigations focusing on additional functional behaviors of this waste-derived material system.

This study presents the morphological and elemental characterization of the tubular structure of thermoformed piezoelectrets with open voids. The thermoformed structures were analyzed without applying the metallized layers required for electrical charging and piezoelectric measurements. Four samples were investigated: two single-layer thermoformed piezoelectret (SLTP) samples with channel widths of 2 mm and 3 mm , and two thermoformed magneto-piezoelectret (TMP) samples with geometries corresponding to those of the SLTP samples. The samples were prepared by pressure thermoforming (250 ^∘ C for 15 s ) of fluorinated ethylene propylene (FEP) films using polytetrafluoroethylene (PTFE) templates. In the TMP samples, a self-adhesive magnetic layer (300 μm thick) was incorporated before the final sealing step by applying an additional layer of FEP on top of the layered assembly. Cross-sectional scanning electron microscopy (SEM) revealed the regular formation of tubular channels, the integrity of the interfaces, and the slight dimensional variations associated with the channel geometry. Energy-dispersive X-ray spectroscopy (EDS) confirmed elemental signatures consistent with FEP and magnetic layer inclusions, with no evidence of external contamination. The results demonstrated the morphological and compositional stability of the structures produced and indicated that wider geometries may require adjustments to the thermoforming parameters to optimize the interlayer cohesion. The results provide relevant structural and compositional parameters for improving the design and quality control of thermoformed piezoelectrets with and without magnetic components.