Highly-sensitive carbon/polymer nanocomposite for wireless multi-directional strain sensing

Advancements in flexible sensors can revolutionize structural health monitoring (SHM) through wireless antenna-based sensing. Microstrip patch antennas (MPAs) serve as effective wireless sensors by detecting strain-induced changes in dimensions and material properties that shift resonant frequency. Carbon-based nanocomposites are promising for flexible strain sensors because they offer high conductivity, flexibility, and sensitivity, making them a suitable candidate for a flexible antenna strain sensor. However, uniformly dispersing carbonaceous nanofillers in polymer matrices remains difficult, leading to inconsistent conductivity and limiting the sensitivity and repeatability of flexible antenna strain sensors. This article explores the design, fabrication, and characterization of novel patch antennas using MWCNT/r-GO/PEDOT: PSS-based nanocomposites, enabling a highly sensitive wireless strain sensor. Morphological and compositional analyses using SEM, FTIR, and Raman confirm the homogeneous and efficient integration of MWCNTs and GO in PEDOT:PSS. A 5.8 GHz nanocomposite-based rectangular patch antenna was designed in COMSOL and fabricated on a 530 μ m FR4 substrate with 15 μ m copper ground. Using a cantilever beam, strain (0–6) × 10 3 μ ɛ is induced towards the length and width direction of the antenna, where MPA with carbonaceous nanocomposite as the patch layer materials, shows a frequency shift of −14.48 kHz/ μ ɛ in the width direction and 6.42 kHz/ μ ɛ in the length direction, which is three times more than the copper based patch antennas. • Carbon nanocomposite antenna sensors shows −14.48 and ＋6.42 kHz/ μ ɛ strain sensitivity. • Multi-directional strain from 0–6000 μ ɛ with stable response in length and width. • Sensitivity repeatable over 50 cycles; variation ± 0.3 kHz/ μ ɛ (length), ± 1 kHz/ μ ɛ (width).