Energy harvesting from vibration and heat differentials are generating commercial operations. Micropelt, a spin-off from Infineon, and Nextreme Thermal Solutions are converting heat differentials into electricity, while Perpetuum, Lumedyne Technologies and MicroGen are generating electricity from vibrations.
According to SEMI, the Infineon spin-off Micropelt is building a fab, which starts production this summer, for its thermal generator, which converts a heat differential to current.
Micropelt reports energy output of 5 to 10mW from the usual temperature difference between a radiator and ambient room temperature.
Nextreme generates electricity from the difference in temperature across an array of flip-chip bumps which include a thin film of 10-20µm single microcrystals of bismuth telluride with special dopants, deposited by an MOCVD process.
Nextreme has demonstrated power output of 16mW with a 70°C differential between the hot and cold sides of the device, for power density of ~0.6W/cm2, more at higher heat differentials.
In vibrational energy harvesting, IMEC has reported generating up to 85 µmW from its AlN piezoelectric film on MEMS cantilevers.
MicroGen Systems, which also uses AlN, claims its arrays of thinner beams can capture a wider than usual range of frequencies, to produce up to 200µmW from 1g of vibrational force, at 50-60Hz and 100-120Hz, plus or minus 5 to 10 Hz.
Lumedyne Technologies claims power density of ~40mW/cc per g of acceleration from its electromagnetic approach to harvesting energy from vibration, which compresses the magnetic field gradient to get greater flux, so the coil doesn’t have to move as far to produce power. Lumedyne reports achieving a level of tens of milliwatts of power — from a prototype about the size of a stack of a dozen quarters.
Perpetuum has a product which is used on AC powered machinery to harvest common “twice-line-frequency” vibration. With 25mg (RMS) vibration within a 2Hz bandwidth, it produces a minimum 0.5mW.
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