Broadband Electromagnetic Properties of Engineered Flexible Absorber Materials

Abstract

Flexible and stretchable materials have attracted significant interest in wearable electronics and bioengineering fields. Recent developments also incorporate embedded microwave circuits and systems with engineered flexible materials that operate over a broad frequency range (≈1–100 GHz). Herein, a simple flip‐chip technique is used to evaluate frequency‐dependent electromagnetic properties of flexible materials and applied to evaluate engineered microwave absorbers based on self‐biased barium hexaferrite composites. On‐wafer error correction and de‐embedding techniques are applied to determine broadband electromagnetic properties of the material‐loaded transmission lines by placing the materials on top of coplanar waveguide transmission lines. Finite‐element simulations along with broadband measurements were employed to estimate the electromagnetic material properties. To demonstrate, flexible polydimethylsiloxane (PDMS) composites are fabricated with barium hexaferrite nanoparticles and complex permittivity and permeability of the composites are quantified under zero magnetic field bias up to 110 GHz. Frequency‐dependent composite permeability is fitted to models describing the ferromagnetic resonance of the self‐biased barium hexaferrite nanoparticles in polydimethylsiloxane, and constituent nanoparticle properties are estimated using the Maxwell–Garnett mixing model. This study paves the way to exploit a wide range of engineered materials in flexible, wearable, and biomedical electronics applications and presents a convenient methodology to extract important broadband electromagnetic properties of nanoparticles for customized electromagnetic applications.

Magneto-Dielectric Composites Characterization Using Resonant Sensor and Neural Network Modeling

“…2, and as observed, the saturation magnetization increases proportionally with the nanoparticle concentration for all the evaluated composites. By the other hand, it is observed no significant variation on the coercivity neither the magnetic susceptibility of the samples when varying the nanoparticles concentration, confirming the retention of composite's superparamagnetic characteristics, a highly desirable condition for low-loss microwave materials [16], [17], [18], [19], [20].…”

MoS2-Based Nanocomposites for Microwave Absorption: A Review

“…In recent years, with the rapid development of the 5G and 6G era of communication technology, widely used electronic products and devices receive extra attention. − At the same time, the use of electronic equipment has caused many problems, such as serious electromagnetic radiation pollution. − As shown in Figure , the electromagnetic radiation generated by various electronic devices not only surrounds people’s daily life but also brings electromagnetic interference between devices, damage to human health, and information security and other problems. − …”