Design and Optimization of Microwave Sensor for the Non-Contact Measurement of Pure Dielectric Materials

This article presents an optimized microwave sensor for the non-contact measurement of complex permittivity and material thickness. The layout of the proposed sensor comprises the parallel combination of an interdigital capacitor (IDC) loaded at the center of the symmetrical differential bridge-type inductor fabricated on an RF-35 substrate (εr = 3.5 and tanδ = 0.0018). The bridge-type differential inductor is introduced to obtain a maximum inductance value with high quality (Q) factor and low tunable resonant frequency. The central IDC structure is configured as a spur-line structure to create a high-intensity coupled electric field (e-field) zone, which significantly interacts with the materials under test (MUTs), resulting in an increased sensitivity. The proposed sensor prototype with optimized parameters generates a resonant frequency at 1.38 GHz for measuring the complex permittivity and material thickness. The experimental results indicated that the resonant frequency of the designed sensor revealed high sensitivities of 41 MHz/mm for thickness with a linear response (r2 = 0.91567), and 53 MHz/Δεr for permittivity with a linear response (r2 = 0.98903). The maximum error ratio for measuring MUTs with a high gap of 0.3 mm between the testing sample and resonator is 6.52%. The presented performance of the proposed sensor authenticates its application in the non-contact measurement of samples based on complex permittivity and thickness.

RFID-Based Microwave Biosensor for Non-Contact Detection of Glucose Solution

Due to the increasing number of diabetic patients, early monitoring of glucose levels is particularly important; therefore, glucose biosensors have attracted enormous attention from researchers. In this paper, we propose a glucose microwave biosensor based on RFID and achieve a non-contact measurement of the concentration of glucose solutions. The Reader is a complementary split-ring resonator (CSRR), and the Tag is comprised of a squared spiral capacitor (SSC). A polydimethylsiloxane microfluidic quantitative cavity with a volume of 1.56 μL is integrated on the Tag to ensure that the glucose solution can be accurately set to the sensitive area and fully contacted with the electromagnetic flux. Because the SSC exhibits different capacitances when it contacts glucose solutions of different concentrations, changing the resonant frequency of the CSRR, we can use the relationship to characterize the biosensing response. Measurement results show that bare CSRR and RFID-based biosensors have achieved sensitivities of 0.31 MHz/mg·dL−1 and 10.27 kHz/mg·dL−1, and detection limits of 13.79 mg/dL and 1.19 mg/dL, respectively, and both realize a response time of less than 1 s. Linear regression analysis of the abovementioned biosensors showed an excellent linear relationship. The proposed design provides a feasible solution for microwave biosensors aiming for the non-contact measurement of glucose concentration.

Non-Contact Measurement of Empathy Based on Micro-Movement Synchronization

Tracking consumer empathy is one of the biggest challenges for advertisers. Although numerous studies have shown that consumers’ empathy affects purchasing, there are few quantitative and unobtrusive methods for assessing whether the viewer is sharing congruent emotions with the advertisement. This study suggested a non-contact method for measuring empathy by evaluating the synchronization of micro-movements between consumers and people within the media. Thirty participants viewed 24 advertisements classified as either empathy or non-empathy advertisements. For each viewing, we recorded the facial data and subjective empathy scores. We recorded the facial micro-movements, which reflect the ballistocardiography (BCG) motion, through the carotid artery remotely using a camera without any sensory attachment to the participant. Synchronization in cardiovascular measures (e.g., heart rate) is known to indicate higher levels of empathy. We found that through cross-entropy analysis, the more similar the micro-movements between the participant and the person in the advertisement, the higher the participant’s empathy scores for the advertisement. The study suggests that non-contact BCG methods can be utilized in cases where sensor attachment is ineffective (e.g., measuring empathy between the viewer and the media content) and can be a complementary method to subjective empathy scales.

Non-contact PIM Measurement Method for Antenna using High-level IM Standard

<p>A non-contact passive intermodulation distortion (PIM) measurement method for antenna using high-level IM standard (HIMS) is described as proposed herein. A novel method to estimate coupling loss between sensing antenna and a sample antenna is proposed, after which a complete one-port non-contact measurement for antenna is realized. Measurements are conducted in three stages: measuring IM characteristics of HIMS, estimating coupling loss using HIMS, and estimating practical PIM level of a sample antenna. A high-level IM standard consisting of a Schottky barrier diode was used for this study. The method enables ready evaluation of practical PIM of a sample antenna from a complete one-port non-contact measurement with excellent stability and repeatability. Then the validity of the proposed method was confirmed experimentally using a printed dipole antenna. After presenting an applicable measurement method for array antenna incorporating the proposed method, its effectiveness was verified experimentally.</p>

Non-contact PIM Measurement Method for Antenna using High-level IM Standard

<p>A non-contact passive intermodulation distortion (PIM) measurement method for antenna using high-level IM standard (HIMS) is described as proposed herein. A novel method to estimate coupling loss between sensing antenna and a sample antenna is proposed, after which a complete one-port non-contact measurement for antenna is realized. Measurements are conducted in three stages: measuring IM characteristics of HIMS, estimating coupling loss using HIMS, and estimating practical PIM level of a sample antenna. A high-level IM standard consisting of a Schottky barrier diode was used for this study. The method enables ready evaluation of practical PIM of a sample antenna from a complete one-port non-contact measurement with excellent stability and repeatability. Then the validity of the proposed method was confirmed experimentally using a printed dipole antenna. After presenting an applicable measurement method for array antenna incorporating the proposed method, its effectiveness was verified experimentally.</p>

Non-Contact Multiscale Analysis of a DPP 3D-Printed Injection Die for Investment Casting

The investment casting method supported with 3D-printing technology, allows the production of unit castings or prototypes with properties most similar to those of final products. Due to the complexity of the process, it is very important to control the dimensions in the initial stages of the process. This paper presents a comparison of non-contact measurement systems applied for testing of photopolymer 3D-printed injection die used in investment casting. Due to the required high quality of the surface parameters, the authors decided to use the DPP (Daylight Polymer Printing) 3D-printing technology to produce an analyzed injection die. The X-ray CT, Structured blue-light scanner and focus variation microscope measurement techniques were used to avoid any additional damages to the injection die that may arise during the measurement. The main objective of the research was to analyze the possibility of using non-contact measurement systems as a tool for analyzing the quality of the surface of a 3D-printed injection die. Dimensional accuracy analysis, form and position deviations, defect detection, and comparison with a CAD model were carried out.