Development, Characterization, and Circuit Modeling of Inkjet-Printed Coupled Ring Resonators for Application in Biological Samples

In the present study, inkjet-printing (IJP) technique is used for development of a planar microwave sensor aimed at dielectric characterization biological samples. The proposed consists two capacitively coupled split-ring resonators (SRRs) fabricated using microstrip technology. A silver-based conductive ink deposited by IJP on conventional 1.6-mm-thick FR4 substrate, thus creating resonant structure. experimental analysis carried out considering water–ethanol mixture as test solution in which ethanol volume fraction varied, thereby changing effective permittivity mixture. this contribution, authors focused their constant under (i.e., real part complex relative permittivity). placed into low-density polyethylene (LDPE) sample vial that arranged surface sensor. No direct contact needed between device and test. effect change related to behavior resonances occurring forward transmission coefficient ( ${S}_{21}$ ) frequency range from 2 3 GHz. affects capacitive coupling SRRs altering separation frequencies. This enables differential measurements, improving its robustness. track variations concentration and, thus, addition, lumped-element equivalent-circuit model presented, changes values lumped elements with are estimated discussed.