With the aid of a 3-D printer, researchers have fashioned soft, quarter-inch-long biological robots out of gel-like material and rat heart cells. When the cells beat, the bio-bots take a step.

Imagine the scenario: you've been told you have a disease that will kill you. But, the doctor adds, your life can be saved if you diligently take your medication. Don't skip a day, don't skip a dosage ...

Handheld devices like this one, used for testing blood sugar levels, could help TB patients monitor their own drug levels. Andrey_Popov/Shutterstock Imagine the ...