Squeezing Out the Leakage
As is commonly known, all silicon transistors drain a device's batteries by using both active power and
leakage power. It is not so widely appreciated that
leakage has become a major concern for IC designers
who work with submicron ( 65 nm and below) process
technologies. In fact, leakage can account for as much
as 30 to 50 percent of total IC power consumption
which is one reason why you have to charge your
laptop and cell phone so often.
If you compress a vein in your arm, this restricts the
flow of blood. Oddly enough, the opposite is true of
silicon: The more you compress it, the more easily
electrons can move through it. This is why transistors in
modern microchips are continuously exposed to
pressures of up to 10,000 ATM (nearly 147,000 PSI).
Unfortunately, squeezing the semiconductor also
increases its leakage current.
However, Tom van Hemert and Ray Hueting of the
Netherlands' University of Twente ( www.utwente.nl)
have recently theorized that you can beat the system by
sandwiching the silicon material between two layers of a
piezoelectric material. Because this material expands
only when the device is in the on state, the pressure and
leakage will slack off in the off state.
At least in theory, a transistor of this type can
operate on a charge of 50 mV rather than the standard
60 mV, offering you the choice of reduced leakage or a
higher on-state current. Details were published in a
recent issue of IEEE Transactions on electron devices. ▲
■ Silicon is
From Chaos to Electricity
Around 2008 or 2009, a civil engineer by the name of Martin Wickett was thinking about what he could
possibly use to drive a generator and came up with an
answer: "whatever." It was then that the Whatever Input to
Torsion Transfer (WITT) transmission was born. In a
nutshell, the WITT is a mechanism that converts energy
collected by two pendulums into unidirectional rotation in
a flywheel, which then drives a generator. Thus, random
movement of the WITT is converted to electricity.
Having undergone a few years of development and
receiving financial and engineering support from a
consortium of universities and other participants, a
working device has now been completed by Supacat Ltd.
( www.supacat.com) — a Devon, UK based developer of
high mobility vehicles. It is slated to undergo extensive
testing by the University of Exeter at their Dynamic
Marine Component Test facility. Because things that float
around in the sea are exposed to substantial wave
movement, it should be the perfect environment for
evaluating the device's performance.
The current version weighs about 100 kg (220 lb), is
built from precision-engineered components and cast
aluminum, and is about the size of a desktop computer.
The beauty of it is that the WITT can be scaled up or
down for a nearly unlimited range of applications.
According to Paul Weston, renewable energy technical
manager for ship repair and conversion company A&P
Falmouth, "The device can also be used in all types of
movement whether on land or at sea, on a backpack,
yacht, or ship. It is a pioneering project that transfers
motion into energy, and we are delighted to be involved
If you want to see one in operation, check out the
videos at www.witt-energy.com. ▲
■ The WITT generates electricity from random motion.
■ BY JEFF ECKERT TECHKNOWLEDGEY 2014
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8 March 2014