Battery-less transmitters pave the way for wireless baby sensors

The radio waves that saturate the air around us may, or may not, give us headaches and cancer, but we can tell you for certain they're capable of powering tiny wireless chips. Renesas Electronics Corp has created a new ultra-low power wireless transmitter that can push data to both Bluetooth and WiFi receivers without the need for a battery or AC adapter. Instead of the typical tens of milliwatts, the little transmitters require only a few microwatts of power, which can be harvested from environmental radio waves through LC resonance. The creators envision adhesive sensors that send a baby's body temperature to laptops and ads that beam coupons to smartphones over short distances -- you know, the sort of stuff NFC can do, but without the specialized hardware.