Abstract
We propose a wireless signal transmitting system by gaining energy from the surroundings. As all of energy needed by this system is gained from the surroundings, there are no necessities for refilling fuel or changing battery. For example, Tire Pressure Monitoring System (TPMS) needs such a maintenance-free sensor system. The system consists of a piezoelectric generator, a capacitor, and a circuit. The circuit watches the capacitor's storage and supplies energy to the transmitter. We made an experiment to gain energy from the deformation of a car wheel with the generator. The energy from the environment is estimated to be about 20mW. This estimation shows that we can drive a transmitter for 1 second after 7 second's charge. We were also able to drive the transmitter in another environment from which the generator gains a little energy, so this system is available not only on wheel's surface but also in general environments.
