Delivering medications has always been a difficult task. Imagine how hard it is to give injections to a herd of sheep–a problem that the commercial wool industry must face. Using a needle in this environment is just not a feasible or sanitary due to issues such as needle breakage and disease transfer.
see A fast reliable multi-dose device was required to overcome this problem. The Cobra Needle-Free Injector was developed at MIT’s BioInstrumentation Laboratory to meet this demand. Drug injection is achieved by penetrating the skin with a micro-stream of liquid drug moving at a high velocity. Unlike other systems that use gas or springs to propel the liquid, the Cobra uses Shape Memory alloy to create the pressure needed to propel the liquid drug through the nozzle at 300 m/s. The advantage of the Shape Memory alloy is that it can generate a large force and contracts much more quickly then conventional actuators. A patent application has been filed for this method.
source site Resources