The labs at MIT are shaking things up – literally – as they just unveiled a tiny device that harvests energy from everyday, low-frequency vibrations. The breakthrough gizmo generates 100 times more power than other devices like it, and it can harvest electricity from a wide range of sources including footsteps, auto traffic, and even swaying bridges. Aimed primarily at supporting wireless sensor networks, the device could be used to create an ambient energy harvesting system right under our feet.
Scientists have been using wireless sensor networks to measure and monitor the environmental conditions of just about everything these days. They can track pollution, measure bridge and building movement, monitor oil pipelines, and even help predict the temperature changes in forests before a mass fire.
Though technological improvements have decreased the energy use of wireless sensor networks, their batteries still need to be changed periodically. With hundreds or even thousands of sensors in a network, the task is quite daunting. MIT’s device, technically called a micro-electromechanical system, or MEMS for short, picks up energy from many levels of vibrations and generates 100 times more power than the recent versions of its kind.
Measuring the size of a quarter, the device is essentially a microchip with a layer of piezoelectric material or PZT on top. PZT is a sort of crystal that naturally generates energy when it is put under stress (Piezo in greek means to squeeze or press). After shaking the microchip in the lab, scientists found it picked up on vibrations from all over the room. One strip of PZT is able to generate about 45 microwatts of power. The team is working towards devices that generate 100 microwatts, which could power a sensor practically forever.