Microfluidic self-quadruplexing SIW antenna with independent tuning and simultaneous sensing of liquid materials

This paper presents a novel microfluidic substrate integrated waveguide (SIW) based self-quadruplexing antenna that integrates independent frequency tunability with liquid dielectric sensing capabilities. The proposed antenna utilized a modified Swastik-shaped slot and embedded microfluidic pockets to dynamically control resonance frequencies. By adjusting the arm lengths of the Swastik-shaped slot, the antenna achieved self-quadruplexing functionality with high port isolation better than 30 dB, and compact footprint of 0.03 [Formula: see text]. To validate its performance, the microfluidic pockets were filled with different standard liquid dielectrics, including ethyl acetate, methanol, ethane, and distilled water to demonstrate frequency tuning. At four distinct resonances, 2.29 GHz, 2.86 GHz, 3.11 GHz, and 3.44 GHz, achieved significant frequency shifts were 340 MHz, 580 MHz, 670 MHz, and 860 MHz, respectively. The proposed design also exhibits a low frequency ratio (FR) of 1.5 and provides a gain of over 5 dBi. Beyond its reconfigurable capabilities, the proposed design enables simultaneous sensing of four different dielectric liquids. The antenna demonstrates exceptional sensitivity of 417.81 MHz/RIU (refractive index unit) for liquid dielectric sensing, and figure of merit (FOM) of 27.85 RIU[Formula: see text] for ethyl acetate detection, making it highly suitable for real-time sensing applications.