Over 10 years ago there was an article written (I don't remember
where)about a
bi-metal or tri-metal wafer which would bend small amounts, with tons
of force when a very small voltage is applied. CAN YOU FIND THIS
ARTICLE ?

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Request for Question Clarification by tutuzdad-ga on 07 Jan 2003 18:48 PST

Dear rob666-ga:

Things tend to change after ten years. Would the product you are
referring to now be known as "memory metal"? Honestly, there is no way
to answer your question without presenting you with every article ever
written on the subject and let you choose which one is the right one.
Perahps you can rephrase your question in order to get a resaonable
respose to something like "can you tell me more about..." rather than
asking for the same 10 year old article that only you can recall.

Let me know if I can provide you with more information about "memory
metal" and I will do my best.

Regards;
tutuzdad-ga

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Request for Question Clarification by hedgie-ga on 07 Jan 2003 20:30 PST

Robb, please, do clarify: 

Such effect, and bimetallic devices based on it, 
can be described. It has nothing to do with memory metals.

Neverthless, you would have to clarify wheather you are
interested in a particular old article, or in the effect and the devices.

Also, please, specify if you are  interested in metals only. Effect is usually
measured in dielectrics or in metal-polymer composites.

In metals, which are conductive, maintenance of static charge is difficult and
so metals  would be less useful in engineering aplications of this effect.

There are sveral related effects. If you explain a bit your application
or purpose, it would help to narrow or widen the topic as appropriate.

Looking forward to your response.

hedgie

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Request for Question Clarification by tutuzdad-ga on 07 Jan 2003 20:48 PST

Thank you for your insight hedgie-ga, but it is customary to allow the
"customer" to clarify his "own" question before assuming we know what
he means in advance of his requested response. I'd feel more
comfortable hearing "his" take on it before I proceed with my research
on the matter or choose to decline.

Regards;
tutuzdad-ga

---

Clarification of Question by rob666-ga on 08 Jan 2003 18:29 PST

This article described a laminate of a metallic outer layer with a
disimilar center metallic material. Once a voltage was applied (using
a small watch battery) the material distorts with great force.
The possible uses mentioned for this product were:
   1) a low power computer fan
   2) a disc brake actuator

It was developed by a company in Texas. (According  to this article,
which may have been in popular mechanics.)


 I would like to know: 

    1) What would the two materials be? (they were described )
    2) Is this reaction possible?
    3) What happened to this idea? (They were developing new uses for
this product.)

                           THANKS---  ROB

Hi, Rob666-ga:

One of the "hot" smart materials these days is something called Ionic
Polymer-Metal Composites (IPMC).  These materials are prepared by
starting with a polyelectrolyte (ionic polymer), which is treated with
an ionic solution of a noble metal salt (gold or platinum) and then
chemically reduced to produce the composite material.  Additional
metal is then bonded on by electroplating to supplement the dendritic
electrode structure produced by ion replacement.

These were featured, alongside some other technologies, in this
Popular Mechanics article from 1999:

[The New Bionic Man]
http://popularmechanics.com/science/medicine/1999/2/new_bionic_man/print.phtml

Though another technology mentioned in the article (artificial taste)
is being pursued at the Univ. of Texas, the folks mentioned in this
article in connection with the use of IPMC's as artificial muscles are
actually associated with the Univ. of New Mexico.  See here for the
first in a series of four recent survey articles on the subject:

[Ionic polymer-metal composites: I. Fundamentals]
http://www.me.unm.edu/amri/SMFundamental.pdf

and an earlier article:

[Ionic Polymer-Metal Composites (IPMC) As Biomimetic 
  Sensors, Actuators & Artificial Muscles- A Review]
http://www.unm.edu/~amri/paper.html

whose abstract reads in part:

"Strips of these composites can undergo large bending and flapping
displacement if an electric field is imposed across their thickness.
Thus, in this sense they are large motion actuators. Conversely by
bending the composite strip, either quasi-statically or dynamically, a
voltage is produced across the thickness of the strip. Thus, they are
also large motion sensors. . . . Also the load characterization of the
IPMC's were measured and showed that these actuators exhibit good
force to weight characteristics in the presence of low applied
voltages. Finally, reported are the cryogenic properties of these
muscles for potential utilization in an outer space environment of few
Torrs and temperatures of the order of -140 degrees Celsius. These
muscles are shown to work quite well in such harsh cryogenics
environments and thus present a great potential as sensors and
actuators that can operate at cryogenic temperatures."

Apropos of these last comments, NASA is planning a mission (MUSES-C)
for later this year to a nearby asteroid's surface.  Cancelled due to
budget constraints, a "Small Science Vehicle" (SSV) palm-sized Rover
was originally planned to be part of the mission, utilizing IPMC's to
effect certain motions on the asteroid:

[NASA flexes its artificial muscles]
http://ndeaa.jpl.nasa.gov/nasa-nde/nde-aa-l/aerospace-america.pdf

The technology is also finding some "down to earth" applications! 
Italian researchers have created a wiggling fishing lure using the
composite strips, which are especially well suited for an aqueous
environment:

[Active Bait with IPMC (Ionic Polymer-Metal Composites)]
(scroll down to page 10)
http://www.aanet.ru/isa/euroxchange/issue7/issue7.pdf

See especially Fig. 3 (on page 11 of the above) which illustrates the
use of a pair of IPMC's back to back to achieve both extension and
contraction (similar to how muscles are paired in anatomy).

Thanks for posting this interesting question; I'd be happy to clarify
further specifics at your request.

regards, mathtalk-ga

Additional Link of Interest

[Emerging Smart Materials: Opportunities for Ceramics]
http://www.spie.org/web/oer/february/feb98/smartmat.html


Search Strategy

Keywords: IPMC actuator
://www.google.com/search?q=IPMC+actuator&hl=en&lr=&ie=UTF-8&oe=UTF-8&as_qdr=all&start=10&sa=N

Keywords: "bimetallic actuator" voltage
://www.google.com/search?hl=en&lr=&ie=UTF-8&oe=UTF-8&as_qdr=all&q=%22bimetallic+actuator%22+voltage&btnG=Google+Search

Keywords: "metal composites" actuator
://www.google.com/search?q=%22metal+composites%22+actuator&btnG=Google+Search&hl=en&lr=&ie=UTF-8&oe=UTF-8&as_qdr=all

Hello,

I am not sure where to begin.  Can you tell me, what is a popular
science-type journal, of an academic journal.

I can offer you many references (both online and otherwise) on the
physico-cheical characteristics of metal laminates, or were you
interested in particular article.

cheers,
deepsea

Dear tutuzdad

   My RFC was not a comment for you, but a question for the asker.

   However, you are certainly welcome to any insight you may find there.
   Asker is still free to choose if he wants to hear about 'memory metals'
   or about electro-mechanical properties of metallic materials.

   Asker can also leave that open, and you are welcome to answer either one or
   both.