Return of the Living Dead 3

Return of the Living Deadis an American romantichorror film released in 1993. The film is the second sequel in the Return of the Living Dead film series but bears little resemblance to its predecessors, as it drops the comedy of those films and replaces it with a more horrorscifi aspect, and a dark romantic theme. The Trioxin substance from previous films also carry over, but with different effects from previous films in the series. Like the ones in previous films of the series, these zombies tend to run rather than walk or limp and are fixated on eating brains. Unlike the previous films, these zombies seem to infect their victims by biting them whereas, in the two previous films, only exposure to Trioxin in either its natural gas state or in water that had been exposed to Trioxin could turn a corpse into a zombie.

The corpse is exposed to 245 Trioxin gas, which reanimates the corpse into a zombie. The military hopes to use the zombies in combat as nighunstoppable soldiers. However, the zombies are impossible to control as they have a terrible hunger for human brains that causes them to constantly attack.To deal with the zombies vicious nature, Sinclair has a plan to permanently attach the zombies to exoskeletons that will also immobilize them when they are not in battle. Reynolds prefers to use a method referred to as paretic infusion to paralyze the zombie until it is needed. This is accomplished by firing a chemical projectile into the forehead of the zombie that causes an endothermic reaction that freezes the zombies brain and temporarily immobilizes it. ........

Source: Wikipedia