Vaccines can be a vital way to stop the spread of disease in some parts of the world. But in underdeveloped countries it turns out that the syringes used for vaccine injections are re-used again and again, which actually results in the spread of other dangerous conditions. To discourage this, Dr David Swann of Huddersfield University in the UK has developed a syringe that turns bright red after use, serving as an obvious warning not to use it again.
The syringes feature a special ink impregnated into the plastic barrel that changes colour when exposed to air. And to ensure this doesn't happen prematurely, the syringes are sealed in a nitrogen-filled pack. When opened, the user has 60 seconds to administer an injection before the syringe turns bright red, indicating they've been used.
As an added deterrent against reuse, the syringe's barrel features a faceted design which actually prevents normal plungers from being retrofitted inside. So in addition to the bright red warning, it turns out the syringes couldn't be re-used anyways. And, the proposed redesign adds just a few cents to the cost of every syringe, so there's really no excuse as to why this concept shouldn't be put into production and adopted worldwide. [Design To Improve Life via Cnet]