Wi-Pie: Energy Harvesting in Mobile Electronic Devices

A recent study puts the number of mobile phones in use around the world at an astonishing 5 billion and these numbers are growing rapidly. This places the increase in energy consumption of mobile phones in the world at an alarming level. Wi-Pie or Wireless-Piezoelectric technique combines RF energy scavenging and piezoelectric energy harvesting technologies to provide an alternative method of powering mobile electronic devices. By placing piezoelectric crystals beneath the keypad of a mobile phone, we intend to generate a small voltage with every key press which could be stored in a secondary storage device like a capacitor. The charge accumulated in the device can then be transferred to the primary storage or the battery so that the use of external chargers can be minimized. Additional power management circuitry is used to intercept the known and the unknown sources of ambient RF radiations. The received RF power is converted to DC and conditioned before it´s delivered to the load. Although the RF energy levels are low, a combination of the harvesting and scavenging techniques will provide a significant source of power.