Post by thread:breathing[OT]

Maybe a little ot ... I'm trying to measure the expansion of chest during breathing using a pic (there You are ;-) ) How would You measure a span of about 10cm ? Usually flexible rubber tubes with quick silver are used, the change of lenght is measured by taking the resistance with a wheatstone bridge. only, Hg on the floor can be hard to hunt ;-) (and sooner or later it gets there ...) The device should be rather small and to be attached to a person easily. And it should be as "electronical" as can be, that is: preferably no mechanical parts ... Any ideas? Christoph

Of course it may be hard to get a hold of, but ECG elctrodes are the best for this sort of thing. And a low current, high frequency source to pass through the leads. Changes in resistance of less than an ohm indicate expansion and contraction. Rob At 01:39 PM 1/24/98 +0100, you wrote: {Quote hidden}>Maybe a little ot ... >I'm trying to measure the expansion of chest during >breathing using a pic (there You are ;-) ) >How would You measure a span of about 10cm ? >Usually flexible rubber tubes with quick silver are used, >the change of lenght is measured by taking the resistance >with a wheatstone bridge. only, Hg on the floor can be hard >to hunt ;-) (and sooner or later it gets there ...) > >The device should be rather small and to be attached >to a person easily. And it should be as "electronical" >as can be, that is: preferably no mechanical parts ... > >Any ideas? > >Christoph > >

A very nice technology for this is called the Rubbery Ruler from Unimelb Limited (U. of Melbourne, AU). Try: http://www.ph.unimelb.edu.au/inventions/rubberyruler/ The technology is a capacitive sensor (C changes with stretching of a device) and is claimed to have been used to monitor body movement is space, fruit growth and others. We tried to arrange a license to manufacture and sell the sensors, but Unimelb's extreme unreasonable expectations forced us to abandon that project (funny.....patents are MANY years old and no commercial products????). I still think the technology offers promise for many niche applications and maybe some mainstream ones. It may work for you. We did much research into manufacturing processes and applications for this technology. If you have any questions, let me know. Good-Luck. Mark A. Corio Rochester MicroSystems, Inc. 200 Buell Road, Suite 9 Rochester, NY 14624 Tel: 716-328-5850 Fax: 716-328-1144 http://www.frontiernet.net/~rmi/ ***** Designing Electronics for Research and Industry *****

<Christoph writes in part> > >Maybe a little ot ... > >I'm trying to measure the expansion of chest during > >breathing using a pic (there You are ;-) ) > >How would You measure a span of about 10cm ? I seem to recall that fibre optics attenuate light in proportion to the radius through which the fibre is bent. Perhaps winding a fibre around an elastic tube -- gum rubber surgical tubing comes to mind -- would make a sensor that when wrapped around the subject's chest would be able to measure movement as a change in transmissitivity. Of course it might be a bit simpler to just measure the change in pressure within the tubing. Put the tubing around the subject's chest. Pressurize the tubing slightly to get a reading on a gauge and then watch it fluctuate. Just ideas... Cheers, Win Wiencke Image Logic Corporation spam_OUTImageLogicTakeThisOuTibm.net

Christoph Klein wrote: > > Maybe a little ot ... > I'm trying to measure the expansion of chest during > breathing using a pic (there You are ;-) ) > How would You measure a span of about 10cm ? > Usually flexible rubber tubes with quick silver are used, > the change of lenght is measured by taking the resistance > with a wheatstone bridge. only, Hg on the floor can be hard > to hunt ;-) (and sooner or later it gets there ...) > > The device should be rather small and to be attached > to a person easily. And it should be as "electronical" > as can be, that is: preferably no mechanical parts ... > > Any ideas? > > Christoph I've seen a system where a laser draws a grid on the patient's chest. The rest is then done in software hooked to a CCD. -- Friendly Regards Tjaart van der Walt .....tjaartKILLspam@spam@wasp.co.za _____________________________________________________________ | WASP International http://www.wasp.co.za/~tjaart/index.html | | R&D Engineer : GSM peripheral services development | | Vehicle tracking | Telemetry systems | GSM data transfer | | Voice : +27-(0)11-622-8686 | Fax : +27-(0)11-622-8973 | | WGS-84 : 26¡10.52'S 28¡06.19'E | |_____________________________________________________________|

Christoph Klein wrote: > > Maybe a little ot ... > I'm trying to measure the expansion of chest during > breathing using a pic (there You are ;-) ) > How would You measure a span of about 10cm ? > Usually flexible rubber tubes with quick silver are used, > the change of lenght is measured by taking the resistance > with a wheatstone bridge. only, Hg on the floor can be hard > to hunt ;-) (and sooner or later it gets there ...) > > The device should be rather small and to be attached > to a person easily. And it should be as "electronical" > as can be, that is: preferably no mechanical parts ... > > Any ideas? > > Christoph Hi, I've read quite a few of the suggestions, so here's mine. Why not use a straightforward measuring tape marked with 0.5mm wide lines, and an optical sensor? The best way I know of to maintain tension on the tape is a 'tensator spring'. This is a pair of rollers with a coiled steel spring wrapped around them. Unfortunately I don't know where to get them from since I've changed jobs. By making the tape a little too long and anchoring it on the measuring device it should be straightforward to apply and remove. If this sounds like a sensible solution, mail me and I'll try and send a sketch. Keith.

Thought Technology makes a very accurate one, which uses a hall effect sensor moving towards and away form a permanent magnet. It works very well. http://www.thoughttechnology.com/ 514-489-8251 C. Webb {Quote hidden}>At 01:39 PM 1/24/98 +0100, you wrote: >>Maybe a little ot ... >>I'm trying to measure the expansion of chest during >>breathing using a pic (there You are ;-) ) >>How would You measure a span of about 10cm ? >>Usually flexible rubber tubes with quick silver are used, >>the change of lenght is measured by taking the resistance >>with a wheatstone bridge. only, Hg on the floor can be hard >>to hunt ;-) (and sooner or later it gets there ...) >> >>The device should be rather small and to be attached >>to a person easily. And it should be as "electronical" >>as can be, that is: preferably no mechanical parts ...

Peter Neubert wrote: > > Get hold of an elastic fiber optic cable (if it has been invented) meassure > the time it > takes to send a pulse and Voila you got the distance :-) Well I suppose if you wrapped it round a couple of million times and used an SX from Scenix I was thinking of sugesting timing ultrsonic pulse along the tube. As you only require the change not absolute distance you probably would not need to bother with compensating for temp and pressure but the guy was looking for a simple solution peterKILLspamcousens.her.forthnet.gr

In message <01bd2a4e$1a38aee0$66010128@baby>, Peter Neubert <.....neubertKILLspam.....BOW.INTNET.MU> writes >Get hold of an elastic fiber optic cable (if it has been invented) meassure >the time it >takes to send a pulse and Voila you got the distance :-) The VPL DataGlove (used in virtual reality applications) used fibre- optic cable to measure finger flexion, with an IR source at one end and a sensor at the other end. They made small cuts in the fibre-optic cable, so that the IR transmission varied as the finger was flexed. Rather crude, but it worked reasonably well. Leon -- Leon Heller: EraseMEleonspam_OUTTakeThisOuTlfheller.demon.co.uk http://www.lfheller.demon.co.uk Amateur Radio Callsign G1HSM Tel: +44 (0) 118 947 1424 See http://www.lfheller.demon.co.uk/dds.htm for details of my AD9850 DDS system. See " "/diy_dsp.htm for a simple DIY DSP ADSP-2104 system.

The simplest thing I can think of is a String Pot. You can wrap the string around the chest, and the resistance of the pot will vary with the expansion. A 16C71 can read the result and display in digital. Regards Tony For the beginner.... PicNPoke Multimedia 16F84 Simulator Assembler, and Tutorial. Now with PicNPlay circuit simulator. Plus animated Address Mode Tutor. http://www.dontronics.com/picnpoke.html

Tjaart van der Walt wrote: > I've seen a system where a laser draws a grid on the patient's > chest. The rest is then done in software hooked to a CCD. Yeah. Nifty system. One use for it was to measure the amount of milk taken by a baby during a feed - without touching the baby of course! It was reckoned to be an improvement on the earlier technique which of course involved a tub of water and hanging them in there to see how much overflowed. That was an area of research I thought would be quite fun. Sure beats what I ONCE did... Cheers, Paul B.

You might consider a pressure sensor or strain gauge measuring the pull of a spring. Gus -- Gus Calabrese Lola Montes WFT Electronics 4337 Raleigh Street Denver, CO 80212 303 964-9670......voicemail wftspam_OUTfrii.com http://www.frii.com/~wft EMERGENCY: 791 High Street Estes Park, CO 80517 if no success with @spam@wftKILLspamfrii.com, try .... KILLspamwftKILLspambigfoot.com then RemoveMEwftTakeThisOuTeudoramail.com