Here's a design that Dracula would love: a subcutaneously-implanted, wireless digital tattoo display whose fuel cell is powered by blood. An entrant into the same Greener Design Competition as the gravity clock, the concept uses Bluetooth to communicate with your portable gadgets—or even devices implanted elsewhere in your body.
Jim Mielke's concept would be implanted beneath the skin on your arm. It then taps into your bloodstream, converting the oxygen and glucose into electric power. The display then "works" by changing the color of smart-ink pixels tattooed over the implant. It also acts as a touchscreen input device, so you could manage your cellphone calls by tapping on your arm. Most creepily, there's potential for a 3G video call to be shown on your skin.
What with this blood-powered idea, the urine rubber and the blood pen, there's clearly a rich vein (ahem) of bodily-fluid-related ideas out there for inventors to tap into. Let's hope this one remains just a concept, though: I'd hate to have to shave my arm to get good quality video from my tattoo. [Core77 via Geekologie]