This book presents recent developments in the field of biosensors and their applications in healthcare. Keywords: Biosensors, Environmental Contaminants, Disease-causing Pathogens, Genetic Material, Tumor Cells, Cancer, Infectious Diseases, Monitoring Molecules in vivo, Aptasensors, Molecularly Imprinted Polymers, Biomarkers, Nanobiosensors, Theranostics, Bio-recognition, DNA Biosensors, Hydroxide Based Biosensors, Nanoparticles Combating Infections. Healthcare.