This book reviews different types of nanomaterials-based-conductive inks used to develop printed strain sensors, printing fabrication methods, and applications such as wearable health monitoring. Printed wearable electronic devices have recently drawn a lot of attention, as shown by the increasing number of publications and commercialized devices covering various facets in emerging fields. Many researchers are working toward optimizing nanoparticle-based-conductive inks for wearable electronics. However, issues related to its stability, dispersion, and annealing temperature often limit its applications. General important information and requirements of flexible electronics for health monitoring are covered in the book chapter. The target audiences are researchers and students who are involved in the development of printed wearable electronics.