Arizona-based company Alcor offers cryonic preservation to its members - the option to freeze their bodies after death, with the intention of being revived when future technology makes this possible.

Currently it has no way of reviving the preserved bodies, but it is optimistic that it will be able to done one day.

But some scientists question whether the methods of preservation are sufficient to stop the bodies from being too badly damaged to ever revive.

BBC Click finds out more.

See more at Click's website and @BBCClick.