According to patent applications,
HP’s memristor design is based on
a sandwich of titanium dioxide
films that loosely resembles the
construction of a capacitor. However,
unlike capacitors, one layer of
titanium film is an insulator while the
other layer is doped so that it is a
conductor. Wires on either side of
the sandwich are used to pass a
charge through the film. Current
through the film lowers the resistance
of the film by a factor of 1,000. In
this respect, the memristor seems a
lot like an active device to me, but
it’s nonetheless classified as a passive
circuit element.
Some of the first applications of
memristors will likely be high-density,
energy-efficient memory devices
that compete with Flash memory
devices. However, as with any new
technology, it’s difficult to predict
what will come of the memristor.
Because the memristor has qualities
of both analog and digital circuitry,
one application identified by HP is
the development of memristor-based
neural networks [2]. Perhaps
memristors will make it possible
to implement affordable, semiautonomous robots with a semblance
of intelligence.
If you’re like me, you probably
can’t wait to order an assortment of
memristors from Mouser or Jameco.
However, we’re not there yet. We’ll
probably have to be content with a
SPICE simulation or other virtual
experience for months, if not a year
or more.
One of the unfortunate aspects
of memristors — from the perspective
of an electronics experimenter eager
to create the first ‘must have’ device
using memristors — is that just about
every imaginable application is
patented. Take a look at uspto.gov or
www.freepatentsonline.com. One
of the most straightforward patent
applications — United States Patent
20080090337 — is for an electrically
actuated switch. The application
provides a good background on
the mathematics and physics of a
memristor. A second patent
application — United States Patent
20080079029, ‘Multi-terminal
electrically actuated switch’ —
provides additional information,
including specifics on materials
and doping.
It’s not likely that memristors
will make time travel or anti-gravity
possible. However, it’s a new
building block that will undoubtedly
have myriad practical applications
in areas ranging from computing
and entertainment to automotive
electronics. And you can be
certain that Nuts & Volts will be
featuring projects that illustrate the
utility of the memristor — just as
soon as I can get my hands on
one. NV
REFERENCES
[1] Chua, L. Memristor — The missing
circuit element. IEEE Transactions on
Circuits Theory, Volume 18, Issue 5,
Sep 1971 Page(s): 507 – 519.
[2] Johnson, RC. First proof of circuit
theory’s ‘missing link?’ EETimes.
Monday, May 5, 2008. Page(s): 1-6.
August 2008 9
