US Patent 8056420 Self-powered sensor

A self-powered sensor is provided for fatigue monitoring and other low power requirement applications. The self-powered sensor is comprised of: a piezoelectric transducer; a non-volatile memory comprised of at least one floating gate transistor; and a current reference circuit adapted to receive a voltage signal from the piezoelectric transducer and operable to output an injection current into the non-volatile memory. The current reference circuit may employ a floating gate transistor operating in a weak-inversion mode.