Preface

Biosensors are analytical devices that convert a biological stimulus into an electrical signal [1]. Biosensors have been utilized in a wide range of applications across various fields, such as in biomedicine (drug discovery, diagnosis, etc.), food safety, processing, environmental monitoring, defense, security, and the marine sector, among others. Biosensors provide better stability and sensitivity compared with conventional methods [2].

This book includes eleven chapters organized into four sections. Together they present the state of the art in current and novel strategies for biosensing.

Section 1 "Nanomaterials in Biosensing"

Section 2 "Wearable Biosensors"

Section 3 "Mathematical Assessment on Biosensors"

Section 4 "Biological Monitoring with Biosensors"

Section 1 includes two chapters. Chapter 1, "Nanomaterial-Enhanced Receptor Technology for Silicon On-Chip Biosensing Application", explains how integrating nanomaterials into biosensor design enhances sensing capabilities due to the large surface area and intrinsic reactivity of nanomaterials owing to their distinctive optical, chemical, electrical, and catalytic properties. The chapter examines the incorporation of silver nanoparticles (AgNPs) into a silicon-on-a-chip biosensor platform to detect cancer biomarkers such as prostate-specific antigen (PSA). Chapter 2, "Nucleic Acids for Electrochemical Biosensor Technology", explains how nucleic acids are used as both recognition agents and target molecules, the way they are used in biosensor technology, and their electrical properties.

Nanomaterials are relevant in several areas. In the case of biosensors, they increase sensitivities and low detection limits, allowing the detection of even individual molecules. Also, nanomaterials can immobilize a greater quantity of bioreceptor units at reduced volumes and act as transduction elements [3].

Section 2 includes three chapters that address wearable biosensors, which are devices that provide continuous, real-time physiological information via dynamic, noninvasive measurements of biochemical markers in body fluids, such as blood, sweat, tears, saliva, and interstitial fluid. Recent developments have focused on electrochemical and optical biosensors, together with advances in the noninvasive monitoring of biomarkers including metabolites, bacteria, and hormones [4].

Chapter 3, "Theranostic Microneedle Devices: Innovative Biosensing and Transdermal Drugs Administration", explains the use of microneedles, how can they be used as biosensors, and their usefulness in drug release. Moreover, the chapter authors claim that microneedle devices allow the continuous monitoring of physiological parameters with very low invasiveness, together with sustained administration of local drugs for long surgical procedures.

Chapter 4, "Control Strategy for Underactuated Multi-Fingered Robot Hand Movement Using Electromyography Signal with Wearable Myo Armband", develops a control strategy for an underactuated robotic hand, based on surface electromyography (sEMG) signal obtained from a wireless Myo gesture armband to distinguish six several hand movements.

Chapter 5, "Advanced Materials and Assembly Strategies for Wearable Biosensors: A Review", discusses various types of wearable biosensors within the context of human health monitoring with a focus on their constituent materials, mechanics designs, and large-scale assembly strategies. The chapter also addresses current challenges and potential future research directions.

Section 3 includes three chapters that examine processes that occur in sensors' layers and at their interface. Chapters also provide analytical and numerical methods to solve equations of conjugated enzymatic (chemical) and diffusion processes. Thus, digital modeling is important for both proximal analytical solutions and experimental data [5].

Chapter 6, "Ultra-Precise MEMS Based Bio-Sensors", discusses state-of-the-art micro-electro-mechanical system (MEMS) sensors used for biosensing applications. It studies a new class of resonant microsensors and presents the device architecture/s based on an array of weakly coupled resonators.

Chapter 7, "Microfluidic Adsorption-Based Biosensors: Mathematical Models of Time Response and Noise, Considering Mass Transfer and Surface Heterogeneity", gives advanced mathematical models of time response and noise of such devices, which are needed to improve the interpretation of empirical measurement results, to achieve the optimal sensor performance. It presents the mathematical models and considers the coupling of processes that generate the sensor signal: adsorption-desorption (AD) of the target analyte particles on the heterogeneous sensing surface, and mass transfer (MT) in a microfluidic chamber.

Chapter 8, "Hybrid Heterostructures for SPR Biosensor", demonstrates the details of surface plasmon resonance (SPR) technology with two recently studied prismbased hybrid heterostructures. These heterostructures are made up of conventional SPR biosensors with two additional layers of recently invented transition metal dichalcogenides, platinum di-selenide (PtSe2), and highly sensitive 2D material, tungsten di-sulfide (WS2).

Section 4 includes three chapters that provide a comprehensive glimpse of different biosensors and their characteristics, operating principles, and designs, based on transduction types and biological components [6].

Chapter 9, "Advanced Biosensing towards Real-Time Imaging of Protein Secretion from Single Cells", summarizes recent advances in real-time imaging of single cellular protein secretion, including label-free and labeling techniques, to unravel the direction for developing a simple and powerful methodology for real-time imaging of single cellular protein secretion.

Chapter 10, "Novel Biosensing Strategies for the *in Vivo* Detection of microRNA", describes the principles and designs of these detection technologies and discusses their advantages as well as their shortcomings, providing guidelines for the further development of more sensitive and selective miRNA sensing strategies in vivo.

Chapter 11, "Electrochemical Response of Cells Using Bioactive Plant Isolates", probes the electrochemical response of model cells using bioactive compounds captured in bio-zeolites or membrane mimetics. The voltage and current fluctuations emanating from studies establish a correlation between cell death and membrane depolarization.
