Right now it would be nice for people to be able to perform a detailed inspection of whatever environment they are in, and of themselves internally. As the future evolves, it could become an exigency. Portable personal biosensing devices for biothreat defense and medical self-diagnosis could become de rigueur, most logically as an extension of current mobile device platforms.
That would be great indeed. But why limit it to biodefense?
On topic: “Cell phones using lens-free imaging promise to improve health monitoring”