  We present an integrated circuit capable of scavenging energy from repetitive
changes in finger touch capacitance. A finger tapping on this ASIC generates a
capacitive change of approximately 770pF. These changes feed into a charge-pump
circuit which stores 320pJ of energy on a 1nF storage capacitor. We present
measurement results and simulations that demonstrate operation. As a
proof-of-concept, we also demonstrate that the harvested energy can power a
ring oscillator which outputs a series of chirps with frequencies ranging from
80Hz to 30kHz as the storage capacitor voltage charges and discharges.
