A New Approach to Determining Liquid Concentration Using Multiband Annular Ring Microwave Sensor and Polarity Correlator

Abstract

This article presents a new approach to determining liquid concentration using a new microwave sensor and polarity correlator. The sensor design incorporates an annular ring resonator having inside three parallel lines, a trapezoid ground plane and a co-planar waveguide (CPW) tapered feeder, which altogether achieve multiple frequency bands. Multiple bands of interest are obtained at the lower end of the microwave spectrum, i.e., from 1–6 GHz, as this region is widely accepted in analyzing various liquid samples. The sensor size is 71 × 40 × 1.6 mm3 with material selection based on an economically available FR4 substrate. The sensor is realized and experimentally validated for its sensitivity by utilizing in-lab prepared aqueous solution samples. Further, liquid concentration is determined by adopting a polarity correlator, which is applied to the sensor’s responses obtained at different values.

mmW Rotman Lens-Based Sensing: An Investigation Study

“…where sign(x) = 1 if x > 0 and −1 if x < 0. This pre-processing step improves the discrimination between the different concentrations, as previously demonstrated in [12]. The pulse fidelity factor p mn i is given by:…”

“…The polarity correlator previously introduced in [ 12 ] can be used to analyze the responses of the Rotman lens when the lens works as a sensor. As discussed in [ 12 ], the polarity correlator exploits the variations present in the whole response of the sensor in order to differentiate between different concentrations by measuring the similarity of a sensor’s response to an unknown concentration with pre-stored sensor responses to known concentrations. To provide comprehensive analysis for all possible Rotman lens responses, this section presents results produced only by simulation.…”

“…These responses corresponding to the index i = 2, 5, 23, 25, 34, and 35 are obtained from ports P2-P2, P5-P5, P5-P2, P5-P6, P6-P8, and P6-P9, with Figure 17 showing their versus the response index i . Therefore, we can consider the determination of a concentration value as a classification problem, along the lines of the approach reported in [ 12 ], but with additional steps exploiting data of more than one port of the Rotman lens. Specifically, the following steps were performed.…”

“…For proof of concept, the sensing was characterized between port numbers (P3–P9). Section 4 considers the signal processing aspect of the design in analyzing the abundant port data via the polarity correlator algorithm, which was presented in our earlier work [ 12 ].…”

Microwave Spoof Surface Plasmon Polariton-Based Sensor for Ultrasensitive Detection of Liquid Analyte Dielectric Constant

“…Due to their possibility for real-time, non-contact and non-invasive measurements, microwave sensors present an excellent solution for a wide range of applications, including dielectric constant sensing [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 ], food quality control [ 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 ], gas sensing [ 20 , 21 , 22 ], detection of biomolecules [ 23 , 24 ], glucose monitoring [ 25 , 26 ], measurements of concentration for liquid solutions [ 27 , 28 ], microwave imaging [ 29 , 30 ], and mechanical motion sensing [ 31 , 32 ]. They can also be combined with other technologies, including microfluidics, which provide compact and cost-effective platforms for rapid detection in small amounts of liquid samples [ 33 , 34 , 35 , 36 ].…”