As mentioned in earlier news, humans seemed destined to design machinery meant to destroy us. Take the blood sensing technology and combine it with a new fuel cell designed to run on human blood, and you have a future where machines don't simply use humans as batteries, rather they'll simply eat us instead. Our doom is being pioneered by Canadian researchers using the enzymes in human blood to power nano-sized devices for medical devices. More detail on the science is available from the IEEE article A Microfabricated PDMS Microbial Fuel Cell.