Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. A jet injector is a fine precision medical ‘’syringe’’ that uses high-pressure, usually powered by compressed air or gas, employed to penetrate the skin with a narrow jet of liquid (medication). More practical than a traditional syringe, a jet injector was proposed several decades ago, initially marketed for mass immunization and insulin delivery. Recently, US scientists announced the development of a new type of jet devices, more flexible than most commercial jet injectors, being able to deliver medicine through the skin without using needles. Learn more about the jet injectors and their subtypes in this book.