Micro electrical generator

There is little point in building tiny micro-electro-mechanical devices (MEMS) if they need big batteries to work. So Washington State University, US, has been working on a radical solution – a microscopic generator that burns hydrocarbon fuel to generate electricity.Within the device, droplets of fuel are deposited onto a flat metal plate (about 1 millimetre to a side) and then ignited. As the plate heats up, drops of liquid mercury travel along a connected tube to a strip of piezoelectric material. Heat from the mercury causes the piezoelectric strip to flex, generating a small pulse of electric power.Some of this power is used to create an electrostatic charge which moves the mercury droplets back towards the hot plate to pick up another dose of heat. This lets the system generate a continuous series of electric pulses.Each micro-generator can only produce about 1 milliwatt of power but an array of several thousand could produce several watts – enough to let MEMS do plenty of useful work.