This study aims to investigate the influence of substrate’s different infill patterns at 20% infill density of micro strip patch antenna (MPA) based sensor performance with a particular focus on the metrics such as radiofrequency (Rf) performance, insertion loss (S11) and specific absorption ratio (SAR) under both loaded and unloaded conditions.
Different 14 infill patterns of polylactic acid (PLA) substrates were fabricated using three-dimensional (3D) printing based on fused filament fabrication with 20% infill density. The Rf and S11 of the MPA pressure sensor sensitivity were experimentally evaluated using a vector network analyser setup by applying a loads of 5 N–25 N. The dielectric constant, Rf and S11 and SAR value were calculated for solid disk (100% infill density) and 20% infill density disk. In addition, mechanical and electromagnetic finite element modelling (FEM) simulations were conducted to correlate simulation with experimental results.
The grid pattern (20% infill density of PLA) exhibits the highest (approximately 139%) dielectric constant value of 9.0 and lesser (approximately 3.5 %) SAR value of 1.470 W/kg, while the solid PLA sample (100% infill density) shows the lowest dielectric constant value of 3.8 and higher 1.520 W/kg. Experimental testing demonstrated a resonance frequency shift from 4.31 GHz (No load), 4.35 GHz (5 N), 4.30 GHz (10 N), 4.27 GHz (15 N), 4.06 GHz (20 N), 3.87 GHz (under 25 N load), accompanied by a corresponding S11 change from −26.95 dB to −17.04 dB, confirming the sensor’s pressure sensitivity.
This study presents comprehensive analysis of 3D-printed infill patterns affecting the Rf, S11 and SAR values of MPA-based pressure sensors. The experimental validation with FEM modelling provides valuable insights for designing customizable and efficient wearable MPA-based pressure sensor using 3D printing technique suiting burn rehabilitation monitoring applications.
