Fun_People Archive
29 Apr
Physics News Update #425 Bits

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From: Peter Langston <psl>
Date: Thu, 29 Apr 99 13:54:56 -0700
To: Fun_People
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Subject: Physics News Update #425 Bits

X-Lib-of-Cong-ISSN: 1098-7649
Excerpted-from: update.425 (PHYSICS NEWS UPDATE)

The American Institute of Physics Bulletin of Physics News
Number 425 April 27, 1999   by Phillip F. Schewe and Ben Stein

PROGRESS TOWARDS A DICK TRACY WATCH.  Introduced in a Jan. 13, 1946 comic
strip, the Dick Tracy watch is a techie's dream: it is a two-way,
voice-activated video phone that fits around a wrist. In work that may lead
to some components for a real-life Dick Tracy watch, Peter Gammel and his
colleagues at Bell Labs/Lucent Technologies have constructed a tiny
(100-micron) pyramid-shaped  microphone on a silicon chip.  According to
Gammel, this is the first microphone built by surface micromachining
techniques, in which various thin films are deposited on a silicon surface
and some of the features are etched away to result in movable parts.  This
process is to be distinguished from bulk micromachining, in which features
are carved out of a silicon surface itself.  The researchers have also built
a very small rf filter, which blocks unwanted radio frequencies and prevents
signals from a phone's transmitter from disrupting its receiver. Made of
aluminum nitride on a silicon surface, it is 100 times smaller than
conventional ceramic filters, by far the largest single component in a cell
phone.  The Bell Labs researchers also built a micron-scale version of an
inductor, a simple loop of wire that helps determine the proper frequency
for communications.  Most important of all, these components can all be
built on the same silicon chip.  Describing these results at the New York
State section  meeting of the APS held at Lucent last week, Gammel
speculates that all of the components for a Dick Tracy watch should be
technologically available by 2005. (See

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