This chip is part of the Body Sensor Network (BSN) project . Conventional wireless sensors are powered from a battery, limiting node lifetime. In contrast, this chip powered by energy harvested from human body heat using a thermoelectric generator (TEG). This, in conjunction with a programmable power management system, allows for indefinite operation of the chip while worn. An ECG experiment was performed on a healthy human subject. First, the chip was set to ECG raw data mode (consuming 397ŒºW from the 1.35V VBOOST node). The chip used the on-chip R-R interval extractor to transmit measured heartrate every 5s operating from a 30mV supply voltage. In AFib detection mode, the R-R and AFib accelerators enable the TX and transmit the last 8 beats of raw ECG (buffered in the data memory) only when a rare AFib event occurs. The total chip power in both the R-R and AFib modes is 19ŒºW.