We have developed a small, handheld or wearable, wireless motion sensor that sends out a short RF pulse whenever it is jerked. The hardware is minimal, as it mainly includes only a piezoelectric foil accelerometer, a CMOS timer, and a single-transistor 300 MHz RF transmitter. As such, the onboard battery should last for many years, and the cost is
Mark Feldmeier, Joseph A. Paradiso