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Bob Brosch
10-06-2005, 10:02 AM
Our firm (www.testresources.com) builds low force dynamic test systems
for tissue engineering, orthopedics et al and use Interface and Sensotec
load cells. Sensotec has a broader low force product line. I have
personally used both for many years. I was the former load cell product
engineer at MTS in early 70's when they used Lebow and helped redirect
their decisions to buy from Interface in 1976. Recently Honeywell bought
Lebow and added them to the Sensotec line so they seem to be intent on
expanding in general. Both firms are good suppliers. Go to
http://www.sensotec.com/loadcellmini.asp.

Bob Brosch
TestResources Inc
Minnesota of course
800 430 6536 X133

********************************

-----Original Message-----
From: * Biomechanics and Movement Science listserver
[mailto:BIOMCH-L@NIC.SURFNET.NL] On Behalf Of Liang, Yongqiang
Sent: Wednesday, October 05, 2005 4:39 PM
To: BIOMCH-L@NIC.SURFNET.NL
Subject: [BIOMCH-L] Responses to my small force sensor post

Some time ago I posted a post to ask for information on small force
sensors
to measure the Groung Reaction Force for mice(body weight around 25
grams).
Here are the responses I have got. As some folks asked for them.
*******
I have seen a different approach taken by Robert Full at UC-Berkeley. He
uses a semi-hard, transparent gel and was able to correlate diffraction
patterns with force in insects.

He is very approachable and would likely provide you information on the
technique.

-jeremy
jemken@uci.edu
******
Interface makes some ultra low capacity load cells (ULC series) in that
range - www.interfaceforce.com - that
only
need a thin aluminum plate to
put the on. Probably ~ $400... Pressure Profile Systems may have a flat
pressure pad in that range too but it will be expensive.
Daniel zzw8@cdc.gov
*******
i'm not sure if there's any way to design a circuit to make these
things work in the range you're describing ... but tekscan
(www.tekscan.com ) makes inexpensive flexible
force
sensing resistors
that are labelled for 0 to 1 pound range. i know you can modify the
drive circuit to increase the range, so i wonder if you can do the
same to decrease the range.

as far as size, they're a bit large (0.375 inch diameter) ... but
again, i know they can make them to custom shapes/sizes ... i just
don't know what the lower limit for size is, or what quantities you
need to order to get custom sizes.
Johnny johnny@alum.mit.edu
********
Dear Mr. Liang,

You can consider Kistler piezoelectricforce sensor. Please visit
www.kistler.com for more information.

If you are located in China, please let me know your phone no., so I can
talk to you on the phone.

Best regards,

Jacky Ma
Regional Manager
ma@kistler.com.cn
_____________________________________
Kistler China Limited
Unit D, 24/F, Seabright Plaza
9-23 Shell Street, North Point, Hong Kong
Tel + 852 2591 5930
Mobile + 852 9651 1747
Fax + 852 2591 1885
http://www.kistler.com
********
Hi
I know a french research professor, Patrick Even, working in Paris, at
the
INAPG institute, who developped small metabolism cage for mice, that
also
can record mice activity with piezoelectric sensors positionned under
the
bottom of the cage. He also created a start-up to sell these original
cages.
You can contact him at this email adress : even@inapg.inra.fr.
Vincent gigot@cesg.cnrs.fr
********
Issues to think about:

Is the sensor stiff enough? If the natural frequency of the sensor is
low,
then you will end up with a lot of low-frequency noise that will screw
up
your signal. Simply for measuring maximum forces this might not be a
huge
deal, but to measure details about the force patterns this might be a
big
concern. I would shoot for a natural frequency >500 Hz.

The following paper might also be useful:

http://polypedal.berkeley.edu/Profs_office/Full/Publications/publication
_reprint_PDFs/Force_OUP.pdf

Devin
jindrich@ucla.edu
--
-lyq