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Posted: October 14, 2008
New record for piezoelectric energy micro harvesters
(Nanowerk News) In the framework of Holst Centre, IMEC
achieved a new record for micromachined piezoelectric energy harvesters,
now delivering an output power of 60µW.
The harvester can be realized with
a simple, low-cost CMOS-compatible production process by using aluminum
nitride (AlN) as piezoelectric material. The low resonance frequency of
only 500Hz makes the device widely applicable. The output power of 60µW is
sufficient to drive simple wireless sensors that intermittently transfer
sensor readings to a master.
Potential applications include tire pressure
monitoring systems (TPMS) or monitoring of industrial equipment.
Piezoelectric energy harvesters.
Energy harvesters convert ambient energy - light, heat, or vibrations -
into electricity. They are indispensible in situations where batteries
cannot be replaced easily.
Examples are autonomous sensor networks that are
distributed over large areas and in locations that are difficult to access.
IMEC's new energy harvester is a micromachined device converting vibration
energy through a piezoelectric transducer. It can be used to generate
energy for sensors in, for example, planes, vehicles, or vibrating
For the new harvester, an experimental output power of 60µW was measured
with an input acceleration of 2g at a resonance frequency of 500Hz. It
consists of a piezoelectric capacitor formed by a Pt electrode, an AlN
piezoelectric layer and a top Al electrode. The capacitor is fabricated on
a cantilever which has a mass on its tip.
When the harvester vibrates, the
mass on the cantilever causes the piezoelectric layer to be stretched,
inducing an electrical power. The use of AlN as piezoelectric material
makes the device compatible with CMOS processes, allowing production at a
Last year, IMEC already showcased a piezoelectric harvester with a reported
40µW output power. But this device had a piezoelectric layer fabricated
with PZT. The current AlN layer has the advantage that it can be made in a
simpler deposition process. Moreover, the PZT device operated at 1.8kHz.
The lower resonance frequency of the new harvester - 500 Hz - corresponds
with vibration frequencies in, for example, industrial equipment or car
tires. This greatly enlarges the field of application for this harvester.
IMEC is a world-leading independent research center in nanoelectronics and
nanotechnology. IMEC vzw is headquartered in Leuven, Belgium, has a sister
company in the Netherlands, IMEC-NL, offices in the US, China and Taiwan,
and representatives in Japan. Its staff of more than 1600 people includes
more than 500 industrial residents and guest researchers.
IMEC's More Moore research aims at semiconductor scaling towards sub-32nm
nodes. With its More than Moore research, IMEC looks into technologies for
nomadic embedded systems, wireless autonomous transducer solutions,
biomedical electronics, photovoltaics, organic electronics and GaN power
IMEC's research bridges the gap between fundamental research at
universities and technology development in industry. Its unique balance of
processing and system know-how, intellectual property portfolio,
state-of-the-art infrastructure and its strong network worldwide position
IMEC as a key partner for shaping technologies for future systems.
Further information on IMEC can be found at www.imec.be.
About Holst Centre
Holst Centre is an independent open-innovation R&D centre that develops
generic technologies for Wireless Autonomous Transducer Solutions and for
Systems-in-Foil. A key feature of Holst Centre is its partnership model
with industry and academia around shared roadmaps and programs. It is this
kind of cross-fertilization that enables Holst Centre to tune its
scientific strategy to industrial needs.
Holst Centre was set up in 2005 by IMEC (Flanders, Belgium) and TNO (The
Netherlands) with support from the Dutch Ministry of Economic Affairs and
the Government of Flanders. It is named after Gilles Holst, a Dutch pioneer
in Research and Development and first director of Philips Research.
Located on the High Tech Campus in Eindhoven, Holst Centre benefits from
the state-of-the-art on-site facilities. Holst Centre has over 100
employees (growing to over 200 by 2010) and a commitment from over 15
industrial partners. www.holstcentre.com