1. Introduction

This chapter delves into the fascinating evolution of biosensors, tracing their origins from chemical sensors designed to detect specific chemicals in various environments. The text highlights the unique combination of biological recognition elements and transducer systems that enable specific, sensitive, and real-time detection of analytes. It explores the applications of biosensors in medical diagnostics, environmental monitoring, food safety, and biotechnology, showcasing their versatility and importance. The chapter provides a detailed historical account of key milestones, including the invention of the glucose electrode by Leland Clark and the development of the first potentiometric biosensor for urea detection. It also discusses the integration of emerging technologies and materials, such as nanocarbons and hybrid nanostructures, which are at the forefront of current biosensor research. The text concludes with an overview of the current state and future prospects of biosensor technology, emphasizing its potential to revolutionize various industries and improve quality of life.