This book covers the microsystem integration aspects of biosensors. It provides an in-depth examination of how biosensors function within complete diagnostic systems and delivers a thorough foundation in both the biological and engineering principles essential for developing functional biosensor platforms. Fundamentals of Biosensor Microsystems, begins with the introduction of biomolecules as bioreceptors and their possible target detection. It follows by elaborating on the techniques of biomolecules extraction; surface modification and treatment; immobilization and functionalization of biosensors. A wide range of biosensors are detailed in this book with deep fundamental explanations. It also explains the fundamentals of biosensors targets, receptors, target manipulations, biosensor detections, and data analyses. The authors also examine various types of sensors including, electrochemical biosensors, electrode-based biosensors, chemical biosensor, optical biosensors, mass-sensitive based biosensors, micromechanical-based biosensors, microfluidic and dielectrophoresis (DEP) biosensors, magnetic-based biosensors, and thermal biosensors. The authors also connect the reader with the applicable emerging technologies related to biosensor microsystems such as, point-of-care (POC) via lab-on-chip (LOC), biosensors, and internet-of-things (IoT). The book is intended for senior undergraduates, postgraduate students, researchers, engineers, industry professionals and medical practitioners who are involved in the field of biosensors and microsystems development.