This book explores the new materials and the resultant new field of piezotronics. The growth and alignment of the zinc oxide nanostructures are discussed in detail because of its wide adoption in this field and its significance in optics, health, and sensing applications. The characterization of the piezotronic effect and how to distinguish it from other similar but, fundamentally different effects, like piezoresistive effect is also considered. The huge potential in the wearable and flexible devices, as well as organic materials, is further examined. The stain/stress sensing is introduced as an example of an application with piezotronic materials.