Embroidered Rectangular Split-Ring Resonators for the Characterization of Dielectric Materials

Abstract

In this paper, we report an embroidered rectangular split-ring resonator (SRR) operating at S band for material characterization based on the differences in dielectric parameters. We designed, fabricated and characterized SRR sensors on a conventional fabric that can be conformally attached over the surface of samples under investigation. The structures are made of conductive threads and can be embroidered on any dielectric fabric at low cost using conventional embroidery methods. We have demonstrated material characterization capability of the sensors using a specific design with a length of 60 mm and a width of 30 mm. We wrapped the sensors on low-density polyethylene (LDPE) bottles filled with deionized (DI) water and common solvents (ethanol, methanol, isopropanol and acetone) in our experiments. We measured the nominal resonant frequency of a specific sensor wrapped around an empty bottle as 2.07 GHz. The shifts in resonant frequencies when the bottle was filled with the solvents follow the dielectric constants of the solvents.

An integrated platform for metamaterial-based sensing and surface acoustic wave-based acoustofluidics utilising circular interdigital transducers

“…During the monitoring duration, the glucose concentration in the solution decreases, therefore the relative permittivity increases around the sensor. At the same time, ethanol is produced which has higher relative permittivity compared to air and the same principle applies 27,62 . The fermentation reaction leads to an increase in effective capacitance of the device and as a result, to a lower resonant frequency.…”

Flexible Platform of Acoustofluidics and Metamaterials with Decoupled Resonant Frequencies

“…SRRs will have resonant frequencies when excited electromagnetically under various electric and magnetic field configurations (when they are coupled to antennas, e.g., monopole or loop antennas). The nature of the resulting resonance depends on excitation conditions and it can be electric, magnetic, or a combination of both [44,51]. When a circulating current path is induced inside the SRR, the resonance is called a magnetic resonance and the fundamental magnetic resonance can be estimated as lumped components consisting of an effective capacitance and inductance [43].…”

“…, in which f is the fundamental magnetic resonance, L and C are the effective inductance and capacitance, respectively) [47]. Altering any of these parameters leads to a shift in the resonance of SRRs and detecting the shift in the resonance is the key mechanism where SRRs have been employed for biomedical [43,[48][49][50], chemical [51][52][53][54], physical [42], and environmental [55,56] sensing applications. Although these electromagnetic metamaterials can be integrated into LOC systems, they cannot make up an LOC device on their own as they lack the capability of microfluidic manipulation.…”

Metal Discovery by Highly Sensitive Microwave Multi-Band Metamaterial-Inspired Sensors

“…In the next section, we present our metamaterial (MTM) and its electromagnetic properties, followed by an MTM array integration with the bowtie to investigate the enhancement of metal detecting sensitivity. [23,35,50] and rectangular [32,34,36,49,55,56] shapes, the most common MTM structures, are combined with a quarter wavelength transmission line or a simple antenna to design a compact electromagnetic contactless sensor. These SRR structures can be optimized as a separate [23,48,57,59,60] or concentric [35,36,49,50,55,56] SRR array, derived from a conventional SRR.…”

“…Multiple resonance bands can be easily manipulated by having MTM structure SRRs of different dimensions. MTM-inspired sensors then can be designed to operate in a single band [36, 37, 41-43, 46-49, 51] or multibands [23,33,34,[59][60][61] with higher sensitivity. MTM-inspired sensors have been employed for a variety of detecting purposes, for instance, liquidor fluid [23-25, 34, 43, 44, 46-48, 53-55, 57, 63, 65-69, 95], solid dielectric material [35,36,38,52,58,62,70], or biomaterials [37,49,50,80,91].…”