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View Full Version : Replies concerning Force Sensing Resistors (FSRs)



Raymond Mckenna
04-03-1995, 01:29 AM
Dear Biomch-l community,

Here are the replies from my inquiry last week concerning force sensing
resistors. There were 11 replies. Thanks to all all replied. This was
very helpful.

The following was the original posting:

I am looking for some information regarding force sensing resistors (fsr's).
I would like to incorporate this material in some hand research we are
performing. Does anyone have specifics regarding the accuracy, resolution,
etc. of this material. In addition, what companies distrubute this material,
and what is the cost? Names and numbers of these companies would be
appreciated.

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#1
Force Sensing Resistors (FSR) are manufactured by INTERLINK ELECTRONICS.
Unfortunately a student has borrowed my litterature on the FSR technology, so
all I can give you at this moment is the address etc. of their european branch:

INTERLINK ELECTRONICS EUROPE
B.P. 8
Zone Industrielle
L-6401 Echternach
G.D. de Luxembourg

Phone (352) 72 011/72 132
FAX (352) 728 262

They do have a US address as well.

Regarding accuracy: Not good - Interlink does *not* market the FSRs as force
sensors, rather as force indicators. However, this technology is used for
measuring forces where no other sensors (with a reasonable cost) are
applicable, for instance inside prosthetic sockets. Someone quite recently
posted a question regarding such a system - maybe the LISTSERV search
facilities can help you track down his/her address.

Anyways, the FSRs display a gigantic nonlinearity, hystheresis and so forth.
The resolution is essentially infinite.


Hope this can help you.

Regards,
Oyvind

--
Oyvind Stavdahl (Siv.ing., Dr.ing. student)

THE NORWEGIAN INSTITUTE OF TECHNOLOGY
Dept. of Engineering Cybernetics Direct line: +47 73 59 43 77
O. Bragstads plass 8 Switchboard: +47 73 59 43 76
N-7034 TRONDHEIM Fax: +47 73 59 43 99
NORWAY Email: stavdahl@itk.unit.no
http://www.itk.unit.no/ansatte/Stavdahl,Oyvind
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#2

From: sankakir@egr.msu.edu

We, at the Biomechanics Evaluation Lab, Michigan State University, are
working on a project that measures the forces different fingers can
exert during grasp with varying wrist rotations. We are currently using
an AMTI hand held force dynamometer (SRMC3A-6-250). We are also working on
using RSG's (Resistance Strain Gauges) to build our own special purpose
"Force Transducers". The RSG's are from Measurement Group Inc. and not
at all expensive. Another company that supplies RSG's is the Omega
technologies company. The price varies depending on the kind and make of
the strain gauges (both dimension and number).

The number for Measurement Group is :
(919) 365 3800 (Tel.) & (919) 365-3945 (Fax)
The number for Omega Technology Inc. :
1-800-622-2378 (1-800 622-best)

I am sure that these companies will offer other probable methods, including
fabricated force transducers.

The number for AMTI is (617) 964-2042 (Tel.) & (617) 964-6234 (Fax)

Hope this helps,

Kiran.

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Kiran Chandra Sanka
Research Assistant
Bio-Mechanics Evaluation Lab
Michigan State University
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Human Being....... it is all about being human.
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#3

From: "Torzilli, Peter A. Ph.D."

Contact Makoto Shimojo, Ph.D., who is using a rubber conductive film for
finger contact. It is exactly what you are doing. I saw his work while in
Japan in Feb.

You can write him at:

National Institute of Bioscience and Human-Technology
1-1 Higashi, Tsukuba, Ibaraki 305, Japan
email: i7601@nibh.go.jp

Good luck with your project.

Best regards,
Peter A. Torzilli, Ph.D.
Laboratory for Soft Tissue Research
Hospital for Special Surgery
NYC
torzillip@hss.edu
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#4

From: "McDonald, Vernon"
You should try Interlink Electronics, they market an extensive series of
FSR's. Last address I had for them was:

Interlink Electronics
1110 Mark Ave
Carpinteria, CA 93013
ph: 805.684.2100
fax: 805.684.8282

Good Luck,

Vernon

PS I would be interested in hearing of other companies that produce similar
materials
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#5

From: ordwayn@VAX.CS.HSCSYR.EDU (Nat Ordway)

We did some experiments a few years back on these transducers. One thing we
found was that the pressure distribution over each transducer shound be
fairly uniform or else you will get varying results. Of course it depends
on the size of the transducer you use, but for many applications in the
biomechanics field the pressure distribution can be nonuniform. Feel free
to email me back if you would like to discuss this further.


Nat Ordway
Department of Orthopedic Surgery
SUNY Health Science Center (315) 464-6462 -->voice
750 E. Adams St (315) 464-6470 -->fax
Syracuse, New York 13210 ordwayn@vax.cs.hscsyr.edu -->email
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#6

I recently posted a request for a recent address for Interlink Electronics,
manufactureres of FSRs. I received about 30 responses but only three
addresses:

Interlink Electronics
546 Flynn Road
Camarillo, California, USA 93012
805-484-8855
805-484-8989 (FAX)
or
1110 Mark Ave
Carpinteria, California, USA 93013-291B
805-684-2100
805-684-8282 (FAX)

There are rumours that Kulite semiconductors is also manufacturing a produce
but I don't know anything about it.

KULITE SEMICONDUCTOR PRODUCTS, INC
One Willow Tree Road
Leonida, New Jersey 07605
tel : 201 461-0900
cable : Kultung
telex : 685 3296
fax : 201 461-0990


Interlink will send you a trial kit containing hundreds of FSRs for you to
try out. Cost is about US$50. The kit contains spec sheets and circut design
information.

Cheers,
Tim Bach.

+-----------------------------------------------------------------------+
| Timothy M. Bach, PhD |
| Senior Lecturer in Biomechanics |
| Deputy Head, School of Human Biosciences |
| Faculty of Health Sciences, La Trobe University |
| |
| Street Address: 607 Swanston Street, Carlton, VIC, Australia |
| Postal Address: Locked Bag 12, Carlton South, 3053, Australia |
| Phone: +61 3 285-5311 |
| FAX: +61 3 285-5184 |
+-----------------------------------------------------------------------+
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#7

Here is the current address of the only company I know of that makes FSRs.

Interlink Electronics
546 Flynn Road
Camarillo, CA 93012

phone:805-484-1331
fax:805-484-8989

hope this helps

fabian


************************************************** ****************************
Fabian E. Pollo, Ph.D.
Assistant Professor
Director, Gait Laboratory
Baylor College of Medicine
Division of Restorative Neurology
and Human Neurobiology
Smith Tower, Suite 1901
6550 Fannin St.
Houston, Texas 77030
Phone: (713) 798-5536
Fax : (713) 798-5489
e-mail: fpollo@bcm.tmc.edu
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#8

I have considered using FSR's for a miniature "force platform" for finger
grip measurements. However, the FSRs from Interlink appear to have a
time-sensitive variation ie when a constant load is applied, the resistance
drops immediately to a certain value but takes some 30 Seconds - 1 minute
to stabilise at a final value. Has anyone else noticed this? Could it be
something to do with air movement from the internal space of the FSR?

John Yelland

.................................................. .................
Technical Services Unit, Faculty of Health Sciences, Carlton Campus,
Latrobe University, Melbourne, Australia.
Tel. (03)285 5332 | Fax. (03) 285 5111 | Locked Bag 12
John Yelland : j.yelland@latrobe.edu.au | Carlton South P.O.
John Horan : j.horan@latrobe.edu.au | Victoria 3053
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#9

From: "McDonald, Vernon"

A couple of years ago I also tried using the Interlink FSR's to monitor the
force applied by the finger tip during grasping activities. We also noticed
the significant time-sensitive variation with a constant load. We were never
able to resolve this satisfactorily, but thought perhaps it was a result of
the material deformation in the FSR's which did not reach equilibrium for 30+
seconds.

You may also find the following of some interest:

Jensen, T. R., Radwin, R. G., & J.G., W. (1991). A conductive polymer sensor
for measuring external finger forces. Journal of Biomechanics, 24, 851-858.

Radwin, R. G., Oh, S., Jensen, T. R., & Webster, J. G. (1992). External
finger forces in submaximal five-finger static pinch prehension. Ergonomics,
35, 275-288.


Regards,

Vernon McDonald
Motor Performance Lab
NASA/JSC
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#10

I have considered using FSR's for a miniature "force platform" for finger
grip measurements. However, the FSRs from Interlink appear to have a
time-sensitive variation ie when a constant load is applied, the resistance
drops immediately to a certain value but takes some 30 Seconds - 1 minute
to stabilise at a final value. Has anyone else noticed this? Could it be
something to do with air movement from the internal space of the FSR?

John Yelland

.................................................. .................
Technical Services Unit, Faculty of Health Sciences, Carlton Campus,
Latrobe University, Melbourne, Australia.
Tel. (03)285 5332 | Fax. (03) 285 5111 | Locked Bag 12
John Yelland : j.yelland@latrobe.edu.au | Carlton South P.O.
John Horan : j.horan@latrobe.edu.au | Victoria 3053
.................................................. ..................

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#11

THere are a few directions to pursue, and sorry I do not have the phone
numbers...
Interlink Electronics, Zarpinteria, CA
Tess Group Corporation, New Jersy
Constantine Trantsas sp? used to work at Interlink
and developed this very good consulting company
called Tess Group
TechScan, Boston, MA

Good Luck.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~
Kimberly A. Dwyer, M.S. Clinical Mechanics Group
Dwyer@ME.QueensU.Ca Mechanical Engineering
Queen's University, Kingston, Canada
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******* END OF REPLIES *********
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************* Raymond McKenna, P.T.
** Physical Therapist/Research Associate
** ** ** ** Texas Woman's University
** ** ** ** School of Physical Therapy
** ** ** ** ** 1130 M.D. Anderson Blvd.
********** ** ** Houston, Texas 77030
** ** (713) 794-2075
******** e-mail: HG_MCKENNA@TWU.EDU