A combined microwave and optical sensor system with application in cancer detection

Cancer remains a significant health problem, despite great scientific advances in recent years. Biomedical imaging procedures are commonly used to facilitate the diagnosis and treatment of different types of cancer. However, there are still many limitations to these diagnostic techniques. To overcome some of these issues, new approaches are urgently needed. This study aims to establish potential new techniques to improve disease staging diagnosis through more accurate detection and allow real-time monitoring of sample characteristics to help the surgeons reduce the number of biopsies for making a diagnosis. An optical probe has been fabricated in our laboratory with specific characteristics resulting from modelling and experimental exploration. This probe produced encouraging results from a tissue phantom with an ability to distinguish between different particle sizes 2, 0.8 and 0.413 μm with various polystyrene spheres in suspension (PS) concentrations. A Microwave cavity resonator showed the ability to distinguish between different saline dilutions for two types of preparation and different PS concentrations with some limitations. Many correction techniques were developed to enhance the quality of the data obtained. A novel T- Structure and capacitive coupling technique enabled a more robust S21 measurement to be made utilising a resonant coaxial probe at microwave frequencies between around 0.1 GHz and 6 GHz. This structure was modelled and used in experimental scenarios leading to the ability to distinguish between various saline dilutions and different concentrations of PS. Additional correction techniques showed a significant improvement in PS detection limits. Some difficulties have been overcome, relating to settling the PS particles in suspension, corrosion of the microwave probe, and signal processing. All of this has led to a novel system design by combined the optical and microwave sensor system to facilitate effective and efficient tumour detection. This novelty demonstrated that this new system could distinguish between different particles sizes by optical detection and dielectric properties by microwave characterisation. The concluding section of this thesis presents the simultaneous detection of PS samples of different concentrations optically and with the microwave probe. This represents the first time such simultaneous measurements have been carried out using a combined probe such as that described here

Electrical Characterization and Detection of Blood Cells and Stones in Urine

Urine contains an immense amount of information related to its physical, chemical, and biological components; hence, it is a promising tool in detecting various diseases. Available methods for detecting hematuria (blood in the urine) are not accurate. Results are influenced by many factors, such as, health and vitals of the patients, settings of the equipment and laboratories, which leads to false positive or false negative outputs. This necessitates the development of new, accurate, and easy-access methods that save time and effort. This study demonstrates a label-free and accurate method for detecting the presence of red and white blood cells (RBCs and WBCs) in urine by measuring the changes in the dielectric properties of urine upon increasing concentrations of both cell types. The current method could detect changes in the electrical properties of fresh urine over a short time interval, making this method suitable for detecting changes that cannot be recognized by conventional methods. Correcting these changes enabled the detection of a minimum cell concentration of 10² RBCs per ml which is not possible by conventional methods used in the labs except for the semi-quantitative method that can detect 50 RBCs per ml, but it is a lengthy and involved procedure, not suitable for high volume labs. This ability to detect a very small amount of both types of cells makes the proposed technique an attractive tool for detecting hematuria, the presence of which is indicative of problems in the excretory system. Furthermore, urolithiasis is also a very common problem worldwide, affecting adults, kids, and even animals. Calcium oxalate is the major constituent of urinary tract stones in individuals, primarily due to the consumption of high oxalate foods. The occurrence of urinary oxalate occurs by endogenous synthesis, especially in the upper urinary tract. In a normal, healthy individual, the excretion of oxalate ranges from 10 to 45 mg/day, depending on the age and gender, but the risk of stone formation starts at 25 mg/day depending on the health history of the individual. This study also addresses the detection of the presence of calcium oxalate in urine following the same label-free approach. This can be done by measuring the changes in the dielectric properties of urine with increasing concentrations of calcium oxalate hydrate (CaC₂O₄.H₂O). The current method could detect dynamic changes in the electrical properties of urine over a time interval in samples containing calcium oxalate hydrate even at a concentration as low as 10 μg/mL of urine, making this method suitable for detecting changes that cannot be recognized by conventional methods. The ability to detect a very small amount of stones makes it an attractive tool for detecting and quantifying stones in kidneys. Using a non-invasive method which also works as a precautionary measure for early detection of some severe ailments, holds a good scope. It forms the basis of the cytological examinations and molecular assays for the diagnosis of several diseases. This method can be considered a point-of-care test because the results can be instantaneously shared with the members of the medical team. Based on these results, it is anticipated that the present approach to be a starting point towards establishing the foundation for label-free electrical-based identification and quantification of an unlimited number of nano-sized particles

MEMS Technology for Biomedical Imaging Applications

Biomedical imaging is the key technique and process to create informative images of the human body or other organic structures for clinical purposes or medical science. Micro-electro-mechanical systems (MEMS) technology has demonstrated enormous potential in biomedical imaging applications due to its outstanding advantages of, for instance, miniaturization, high speed, higher resolution, and convenience of batch fabrication. There are many advancements and breakthroughs developing in the academic community, and there are a few challenges raised accordingly upon the designs, structures, fabrication, integration, and applications of MEMS for all kinds of biomedical imaging. This Special Issue aims to collate and showcase research papers, short commutations, perspectives, and insightful review articles from esteemed colleagues that demonstrate: (1) original works on the topic of MEMS components or devices based on various kinds of mechanisms for biomedical imaging; and (2) new developments and potentials of applying MEMS technology of any kind in biomedical imaging. The objective of this special session is to provide insightful information regarding the technological advancements for the researchers in the community

Biosensors for Diagnosis and Monitoring

Biosensor technologies have received a great amount of interest in recent decades, and this has especially been the case in recent years due to the health alert caused by the COVID-19 pandemic. The sensor platform market has grown in recent decades, and the COVID-19 outbreak has led to an increase in the demand for home diagnostics and point-of-care systems. With the evolution of biosensor technology towards portable platforms with a lower cost on-site analysis and a rapid selective and sensitive response, a larger market has opened up for this technology. The evolution of biosensor systems has the opportunity to change classic analysis towards real-time and in situ detection systems, with platforms such as point-of-care and wearables as well as implantable sensors to decentralize chemical and biological analysis, thus reducing industrial and medical costs. This book is dedicated to all the research related to biosensor technologies. Reviews, perspective articles, and research articles in different biosensing areas such as wearable sensors, point-of-care platforms, and pathogen detection for biomedical applications as well as environmental monitoring will introduce the reader to these relevant topics. This book is aimed at scientists and professionals working in the field of biosensors and also provides essential knowledge for students who want to enter the field

Imaging Sensors and Applications

In past decades, various sensor technologies have been used in all areas of our lives, thus improving our quality of life. In particular, imaging sensors have been widely applied in the development of various imaging approaches such as optical imaging, ultrasound imaging, X-ray imaging, and nuclear imaging, and contributed to achieve high sensitivity, miniaturization, and real-time imaging. These advanced image sensing technologies play an important role not only in the medical field but also in the industrial field. This Special Issue covers broad topics on imaging sensors and applications. The scope range of imaging sensors can be extended to novel imaging sensors and diverse imaging systems, including hardware and software advancements. Additionally, biomedical and nondestructive sensing applications are welcome

TRANSIENT AND MECHANICAL PROPERTIES OF POLY(PHTHALALDEHYDE) AND THE VARIABLE FREQUENCY MICROWAVE CURING OF HIGH-PERFORMANCE THERMOSETS

Research presented in this thesis is split into two parts. The first section involves tuning the transient and mechanical properties of poly(phthaldehyde) to form a flexible, liquefiable transient material that can depolymerize upon the flick of a metaphorical switch. Such materials can be useful for devices designed to vanish into their surroundings once used. This application-based research required further understanding of how plasticizer additives work to not only make flexible films in an efficient manner, but how they can also serve to decrease the freezing point of o-phthalaldehyde, poly(phthaldehyde)’s monomer unit, upon degradation such that said devices can effectively disappear. Chapter 1 section 1.1 introduces how poly(phthalaldehyde) works as a transient material, and Chapter 1 section 1.2 describes some important fundamental concepts pertaining to how plasticizers can efficiently provide flexibility to polymers and how they work to reduce poly(phthaldehyde)’s freezing point upon depolymerization. Chapter 2 describes an initial approach used to successfully make flexible poly(phthaldehyde) films, and Chapter 3 describes an improved approach utilizing fundamental principles discussed in Chapter 1 section 1.2. Lastly, challenges regarding flexible poly(phthaldehyde)’s low strength are discussed. The second section involves studying the variable frequency microwave curing of epoxy and cyanate ester resins. Such resins are used for a broad range of applications, including microelectronic packaging, circuit board substrates, lightweighting, high- temperature performance parts, etc. Regardless of the application some thermosets, particularly those that possess a high glass transition temperature, require elevated temperatures above 100°C and cure times above 2 hours for complete cure. Variable frequency microwave heating as an alternative to conventional, thermal heating has been proposed as a method for reducing cure times and temperatures. However, proposed and sometimes conflicting microwave heating phenomena described by scientists and engineers are still not very well understood. Thus, the overarching goal of this section is to better understand and use microwave-heating mechanisms that can be useful in reducing thermoset cure times. This involves using a microwave field’s ability selectively heat reactive species (i.e. a catalyst) at the microscopic level, which can occur when two different materials of dissimilar dielectric parameters are mixed. Chapter 4 briefly summarizes important fundamentals of matter-interactions with microwave electromagnetic fields, and how it pertains to selective heating phenomena. Chapter 5 and 6 describe the microwave curing of high glass transition temperature, homogeneous epoxy and cyanate esters respectively. Chapter 7 describes microwave enhanced curing of cyanate ester resin upon the addition of graphene and reduced graphene oxide, two microwave-absorbing, catalytic fillers. Finally, the problems regarding quantifying selective heating phenomena and dielectric property characterization are described.Ph.D