That's a hard one, there are so many! The 'sensorium' is a kind of neural transmitter and at different radiation levels it communicates with the brain via receptors' embedded into the individual. They create a world of simulations and real virtuality. But one of my favourites is the whole area of synthetic biology and its products which I call "quasibio materials". With neural technology for example, one of the characters has an artificial leg which of course is completely indistinguishable from the real thing both to him and to others. Quasibio materials are synthesised in the laboratory and are fundamental for the people of the future who need to be protected not only from poisonous air and water but also from the aggressive populations who live outside. This is achieved by the creation of "biobarriers" using quasibio materials. Biobarriers are living things, a bit like plants but genetically programmed and provided with basic artificial intelligence very useful in checking who is coming and going.
I can assure you though that there are many more applications and inventions based on scientific facts with some additions, which is where the fiction comes to help!

The Question

Q13 - What's the best piece of future technology in Change of State?