The idea for the mechanism inside the syringe works on the same principle as a cocktail umbrella. In fact, it is where the idea originally came from.

After the initial use, the plunger in the syringe becomes immobilized. And if an individual tries to remove the plunger, the needle breaks off so it cannot be used again.

"I came up with the idea after reading an article about AIDS," says Elizabeth. At the time, Elizabeth's chemistry class was also using a syringelike device to demonstrate the relationship between pressure and volume.

"We wrote up our idea and entered it in the NYNEX Science and Technology Awards competition," says Gabriella. "We didn't have to make a prototype [model]," she adds, "but we had to write a paper describing the reason for the invention, and the invention itself. "Our invention won first prize at the competition: $15,000 each and grant money to develop the intervention with a university," says Gabriel.