This book presents a comprehensive study covering the design and application of microwave sensors for glucose concentration detection, with a special focus on glucose concentration tracking in watery and biological solutions. This book is based on the idea that changes in the glucose concentration provoke variations in the dielectric permittivity of the medium. Sensors whose electrical response is sensitive to the dielectric permittivity of the surrounding media should be able to perform as glucose concentration trackers. At first, this book offers an in-depth study of the dielectric permittivity of water–glucose solutions at concentrations relevant for diabetes purposes; in turn, it presents guidelines for designing suitable microwave resonators, which are then tested in both water–glucose solutions and multi-component human blood plasma solutions for their detection ability and sensitivities. Finally, a portable version is developed and tested on a large number of individuals in a real clinical scenario. All in all, the book reports on a comprehensive study on glucose monitoring devices based on microwave sensors. It covers in depth the theoretical background, provides extensive design guidelines to maximize sensitivity, and validates a portable device for applications in clinical settings.

Although noninvasive, continuous monitoring of glucose concentration in blood and tissues is one of the most challenging areas in medicine, a wide range of optical techniques has recently been designed to help develop robust noninvasive methods for glucose sensing. For the first time in book form, the Handbook of Optical Sensing of Glucose in Biological Fluids and Tissues analyzes trends in noninvasive optical glucose sensing and discusses its impact on tissue optical properties. This handbook presents methods that improve the accuracy in glucose prediction based on infrared absorption spectroscopy, recent studies on the influence of acute hyperglycemia on cerebral blood flow, and the correlation between diabetes and the thermo-optical response of human skin. It examines skin glucose monitoring by near-infrared spectroscopy (NIR), fluorescence-based glucose biosensors, and a photonic crystal contact lens sensor. The contributors also explore problems of polarimetric glucose sensing in transparent and turbid tissues as well as offer a high-resolution optical technique for noninvasive, continuous, and accurate blood glucose monitoring and glucose diffusion measurement. Written by world-renowned experts in biomedical optics and biophotonics, this book gives a complete, state-of-the-art treatise on the design and applications of noninvasive optical methods and instruments for glucose sensing.

Diabetes is a disease that afflicts millions worldwide. To control the effects of this disease, diabetics must check their blood glucose levels on a regular basis. Currently, all daily glucose monitoring techniques are invasive, requiring a sample of blood. Microwave sensors are non-destructive and non-contact measuring devices, making them ideal for the measurement of parameters in industrial processes. Current uses of microwave sensors range from measuring moisture content of corn chips to measuring concentration of a solute in water. If a microwave sensor were developed to determine blood glucose concentration, it could be the first daily-use glucose-measuring technique that is truly non-invasive. This thesis provides background on diabetes and microwave measurement. From this background, a sensor is developed and its advantages are illustrated. The thesis concludes by making suggestions for improving the sensor and recommendations on how to implement the sensor into a useful product.

An essential reference for any laboratory working in the analytical fluorescence glucose sensing field. The increasing importance of these techniques is typified in one emerging area by developing non-invasive and continuous approaches for physiological glucose monitoring. This volume incorporates analytical fluorescence-based glucose sensing reviews, specialized enough to be attractive to professional researchers, yet appealing to a wider audience of scientists in related disciplines of fluorescence.

Non-invasive measuring techniques for determining biological parameters are more heavily researched with the growth of the biomedical industry. One of the top areas in non-invasive research deals with diabetes. This disease affects more than 20 million people in the United States, and there is an increasing desire to find a testing process that is non-invasive, easy to use, and safe for users. Microwave technology has improved greatly during recent years and is now seen more often in conjunction with biomedical research. Microwaves are capable of taking measurements of materials inside of a closed volume without the need to come into contact with the material. This makes them ideal for measuring biological parameters, specifically glucose concentrations in the blood. This thesis expands on the development of a microwave sensor to non-invasively measure blood glucose levels and will examine the possibility of developing a calibration for a device using the microwave sensor.

Affordable, sensitive, selective, fast-responding, label-free sensors are currently in high demand for many of today's applications and technologies, particularly in the food industry, bio-sensing applications, and quality control. In addition, modern technologies such as a lab-on-a-chip involve microfluidic analysis, which requires highly accurate and miniaturized sensing systems. These systems can be implemented in biomedical applications such as point-of-care diagnostics, as well as in environmental monitoring, agriculture, biotechnology, and public health and safety. A need, therefore, exists for highly accurate and reliable sensing systems that can meet the requirements of these applications. This dissertation presents electrically-small planar microwave resonators for the design of near-field sensors that can satisfy the needs of the aforementioned applications. This thesis proposes a number of novel concepts related to miniaturization and the enhancement of the sensitivity of electrically-small sensors. In the first part of the thesis, an analysis of the sensitivity of complementary split-ring resonators (CSRRs) with respect to changes in resonator topology is presented. Eigenmode solvers, circuit models, numerical simulations, and laboratory measurements were all employed for the analysis. The results show that the resonance frequency is adjustable and scalable. The second part of the thesis proposed an ultrasensitive near-field sensor for detecting submillimeter cracks in metallic materials. Experimental measurements revealed that a surface crack of 200 um wide and 2 mm deep results in a 1.5 GHz shift in the resonance frequency. The results led to the idea of utilizing CSRRs for designing near-field sensors for crack detection in dielectric materials. The work was further extended to increase the sensitivity of planar CSRRs to detect the presence of dielectric materials. This concept is based on increasing the sensing areas per unit length and on the utilization of multiple, identical, and coupled resonators. Although the electromagnetic energy stored in electrically-small planar resonators is concentrated primarily in an electrically-small volume, most of that energy is located in the host substrate, thus limiting the sensitivity required for detecting changes in the material under test (MUT), which differs from the host substrate. For this reason, a sensor designed for enhancing the EM energy stored in the sensing volume that is exposed to the MUT is proposed. The design concept is based on the use of a three-dimensional capacitor. For validation purposes, a complementary electric-LC resonator (CELCR) and two metallic bars were utilized for designing the sensor for dielectric materials. Furthermore, by adopting the concept of three-dimensional capacitors, microwave sensors based on planar SRRs are introduced in order to 1) enhance the sensitivity, 2) allow for flexible tunability, and 3) create novel sensors for fluidic applications. For validation purposes, an SRR-based sensor was designed and tested using numerical simulation and experiments to detect fluid materials and fluid levels. The SRR with the three-dimensional capacitors was also utilized to design probes for the near-field scanning microscopy. An additional component of this research was, therefore, an exploration of the miniaturization of CELCR sensing areas so that these devices could be loaded with three-dimensional capacitors in order to design a sensitive near-field sensor for microscale-based technologies. The ability of the sensor to detect the presence of magnetic materials was also investigated numerically. For applications in which flatness or compactness is a relevant factor, enhancing sensitivity with the use of three-dimensional capacitors is not an ideal solution. Although classical planar antennas such as patch antennas are subject to a lack of EM energy localization in small areas, the adoption of the split concept, utilized in electrically-small resonators, can improve these antennas for use in designing near-field microwave sensors. This thesis proposed a planar microwave sensor based on an annular ring resonator loaded with a split, thus enabling it to operate at lower frequencies and to enhance the quality factors. The sensor was tested experimentally with respect to characterizing dielectric slabs and detecting the presence of fluidic materials. The last part of the thesis introduced the concept of an intelligent sensing technique based on the modulation of the frequency responses of near-field microwave sensors for the characterization of material parameters. The concept is based on the assumption that the physical parameters being extracted are uniform over the frequency range of the sensing system. The concept is derived from the observation of the sensor responses as multidimensional vectors over a wide frequency range. The dimensions are then considered as features for a neural network. The concept has been demonstrated experimentally for the detection of the concentration of a fluid material composed of two pure fluids.