Pressure switch for prosthesis?

[hamonrye]

I am a prosthetist and as such I design and fabricate artificial limbs for amputees. I have noticed a recurring problem with dysvascular diabetics in that they often have no protective sensation. When their prosthesis is fitting correctly the pressures within the socket (the part their "stump" goes in) are evenly distributed. When for whatever reason (usually swelling resulting in a volume increase) it is not fitting properly the pressures become very high at the bottom of the socket and can cause the skin to break down. This particular patient population has no protective sensation (pain) to tell them to take the prosthesis off and address the problem. I was wondering how difficult it would be to build a device to warn them of high pressures in the end of the socket by a warning light or a vibration or sound.

If there was a pressure switch made that I could put in the end of the socket and wire to a light and battery they could see the light come on and know that there was a problem. I was wondering if anyone here has any ideas on how to build such a device that they would like to share.

Thanks

 

[jraef]

I think IRStuff is on the right track. Having a simple microprocessor can allow tailoring to fit an activity level and filtering out unwanted signal spikes. Here however is a pressure sensing fabric that would suit the purpose in his scenario probably better than an industrial strain gauge because it can be washed, and anything in contact with skin for any length of time will need washing.

http://www.eleksen.com/index.asp?mainsection=2&pageID=195

I also agree with the University research concept. Find one that specializes (or wants to) in biomed and challenge them with this. As to who pays for it, any new technology advance in biomed tends to be resisted by those who must pay, but if you find a skilled advocate who can convince them that the long-term savings are greater due to avoided colateral costs of ignoring the problem, them it can move somewhat more rapidly.

I would suggest contacting amputee support groups and presenting your idea to them. I have a friend who lost a foot in an auto accident. This problem is not confined to diabetic neuropathy patients. Even if they have lots of feeling elsewhere, the amputation site itself is often associated with loss of nerve function. As her muscles atrophy, she often makes the same mistakes in fitting socks and doesn't realize the consequences until damage is done.

"Venditori de oleum-vipera non vigere excordis populi"

 

[itsmoked]

Hey hamonrye: I just got spammed through the mail by a company called; Flexpoint. (

http://www.flexpoint.com)

Thought about your project.

They apparently make flexible resistance sensors.
They sent me samples of three different ones. Looks like they can make checkerboard patterns, etc.

You might ask for a brochure from them, then you'll have something to check out, and improve ideas with.

 

[jraef]

Oooooh, I shudder to think that spam had a useful purpose...

 

[itsmoked]

Yeah, it makes one ponder...

 

[sreid]

Several of these plus electronic would likely work well.

http://www.tekscan.com/flexiforce/specs_flexiforce.html