Expansion and variable resistance ...
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Posts: 46,084
Here's an odd question as with all these things I think it's better to
explain the exact application.
In addition to being a Focus Puller I also work in a centre for children
with disabilities occasionally. One on the young people who is paralysed
from the waist down has to use a Catheter. At the moment they have a
timer that buzzes every couple of hours or so to remind them to empty it
whether it is full or not. As well as not being very discrete it means
lot's of extra trips when the thing is only half full.
My idea was to rip all the guts out of a pager except for the little motor
and the buzzer. The idea would be that at 70% full it would vibrate for a
short time, at 80% for longer time at 90% for an even longer time and
continuously at 95%. The switch on the pager could select vibrate or
Buzz with a centre off position. All this is very easy.
What I need is something like a rubber band that upon expansion would change
it's resistance that we could strap with Velcro round the bag itself to give
an idea of how much the bag has expanded.
Does anyone have a good idea of what I could use for this ?
Justin Pentecost
explain the exact application.
In addition to being a Focus Puller I also work in a centre for children
with disabilities occasionally. One on the young people who is paralysed
from the waist down has to use a Catheter. At the moment they have a
timer that buzzes every couple of hours or so to remind them to empty it
whether it is full or not. As well as not being very discrete it means
lot's of extra trips when the thing is only half full.
My idea was to rip all the guts out of a pager except for the little motor
and the buzzer. The idea would be that at 70% full it would vibrate for a
short time, at 80% for longer time at 90% for an even longer time and
continuously at 95%. The switch on the pager could select vibrate or
Buzz with a centre off position. All this is very easy.
What I need is something like a rubber band that upon expansion would change
it's resistance that we could strap with Velcro round the bag itself to give
an idea of how much the bag has expanded.
Does anyone have a good idea of what I could use for this ?
Justin Pentecost
Comments
>Here's an odd question as with all these things I think it's better to
>explain the exact application.
>
>In addition to being a Focus Puller I also work in a centre for children
>with disabilities occasionally. One on the young people who is paralysed
>from the waist down has to use a Catheter. At the moment they have a
>timer that buzzes every couple of hours or so to remind them to empty it
>whether it is full or not. As well as not being very discrete it means
>lot's of extra trips when the thing is only half full.
>
>My idea was to rip all the guts out of a pager except for the little motor
>and the buzzer. The idea would be that at 70% full it would vibrate for a
>short time, at 80% for longer time at 90% for an even longer time and
>continuously at 95%. The switch on the pager could select vibrate or
>Buzz with a centre off position. All this is very easy.
>
>What I need is something like a rubber band that upon expansion would change
>it's resistance that we could strap with Velcro round the bag itself to give
>an idea of how much the bag has expanded.
>
>Does anyone have a good idea of what I could use for this ?
>
>Justin Pentecost
>
>Hi Justin -
You might want to look at this stretch sensor:
http://merlinsystems.hypermart.net/pages/html/stretch.html
Regards,
Bruce Bates
empty it hangs straight down and the sides are almost flat. As it fills, the
sides bulge and bend the sensor.
Jameco has them for about $10
https://www.jameco.com/cgi-bin/ncommerce3/ProductDisplay?prmenbr=91&prrfnbr=
4137&cgrfnbr=501&ctgys=
or www.jameco.com -- item # 150551
> Here's an odd question as with all these things I think it's better to
> explain the exact application.
>
> In addition to being a Focus Puller I also work in a centre for children
> with disabilities occasionally. One on the young people who is
paralysed
> from the waist down has to use a Catheter. At the moment they have a
> timer that buzzes every couple of hours or so to remind them to empty it
> whether it is full or not. As well as not being very discrete it means
> lot's of extra trips when the thing is only half full.
> What I need is something like a rubber band that upon expansion would
change
> it's resistance that we could strap with Velcro round the bag itself to
give
> an idea of how much the bag has expanded.
>
> Does anyone have a good idea of what I could use for this ?
> >Hi Justin -
>
>You might want to look at this stretch sensor:
> http://merlinsystems.hypermart.net/pages/html/stretch.html
>
>Regards,
>
>Bruce Bates
>
>That is EXACTLY what I needed [noparse]:)[/noparse] Thankyou so much [noparse]:)[/noparse]
>
>Justin
I would be interested to see a 'real' datasheet on this product.
Mainly to find out what sort of repeatability you can expect over
several stretching cycles and the duration of cycle life itself.
Beau Schwabe Mask Designer IV - ATL
National Semiconductor Enterprise Networking Business Unit
500 Pinnacle Court, Suite 525 Wired Communications Division
Mail Stop GA1 Norcross, GA 30071
You might want to look at this stretch sensor:
http://merlinsystems.hypermart.net/pages/html/stretch.html
Regards,
Bruce Bates
That is EXACTLY what I needed [noparse]:)[/noparse] Thankyou so much [noparse]:)[/noparse]
Justin
circumference won't change. Which is what you're measuring. It's the same
empty or full. Unless the bag is stretchy itself (rubber). Am I missing
something here?
Mark
Original Message
From: "Justin Pentecost" <justin@k...>
To: <basicstamps@yahoogroups.com>
Sent: Friday, March 29, 2002 2:35 PM
Subject: [noparse][[/noparse]basicstamps] Expansion and variable resistance ...
> >Hi Justin -
>
> You might want to look at this stretch sensor:
> http://merlinsystems.hypermart.net/pages/html/stretch.html
>
> Regards,
>
> Bruce Bates
>
> That is EXACTLY what I needed [noparse]:)[/noparse] Thankyou so much [noparse]:)[/noparse]
>
> Justin
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
tenner so I have little to lose by trying. The bags are like the ones you
have when you are giving blood and when empty they are flat as they fill up
they become oval shaped. You are correct of course the circumference does
not change The idea I had was to have a flat plastic (ridged) strip which
Velcro's to one side. This plastic strip has two lugs either end. The
sender would hard mounted at either end and have a wide elastic in the
middle.
There is one very important point here. The resistance that the sender
gives must never be so great or springy that it will force urine to flow
back up the tube.
I had another idea which I have to call someone about tomorrow. It might
be possible to actually incorporate the sensor into the strap that hangs the
bag (which removes all the above objections and dangers). So basically the
strap (which is elastic anyway) becomes a spring balance.
Justin
Original Message
From: Mark Schmidt [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=GIN0mW9FncTwPq5VgkIK6VRFOqM1BcSYGijB2_jXNhomgaWZDP5qyoz2k8KsPz7P0j7AaM6omyqs8tI]mschmidt@g...[/url
Sent: 29 March 2002 21:03
To: basicstamps@yahoogroups.com
Subject: Re: [noparse][[/noparse]basicstamps] Expansion and variable resistance ...
I may be wrong here, but if you wrap this device around the bag, the
circumference won't change. Which is what you're measuring. It's the same
empty or full. Unless the bag is stretchy itself (rubber). Am I missing
something here?
Mark
Original Message
From: "Justin Pentecost" <justin@k...>
To: <basicstamps@yahoogroups.com>
Sent: Friday, March 29, 2002 2:35 PM
Subject: [noparse][[/noparse]basicstamps] Expansion and variable resistance ...
> >Hi Justin -
>
> You might want to look at this stretch sensor:
> http://merlinsystems.hypermart.net/pages/html/stretch.html
>
> Regards,
>
> Bruce Bates
>
> That is EXACTLY what I needed [noparse]:)[/noparse] Thankyou so much [noparse]:)[/noparse]
>
> Justin
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
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have you considered just using a sensor that would trigger based on
weight? Either a piezo-resistive sensor under the bag, or a simple
switch that triggers when the weight is in excess of a set amount.
Urine should have at least the same density as water (usually slightly
higher), thus a bag with 400 mls of urine in it will weigh at least 400
grams more than an empty bag- that's an increase in weight that should
be easy to detect.
Good luck, and please let us know how it all works out.
peter
buzzer
Ben
Justin Pentecost <justin@k...> wrote: Here's an odd question as with all
these things I think it's better to
explain the exact application.
In addition to being a Focus Puller I also work in a centre for children
with disabilities occasionally. One on the young people who is paralysed
from the waist down has to use a Catheter. At the moment they have a
timer that buzzes every couple of hours or so to remind them to empty it
whether it is full or not. As well as not being very discrete it means
lot's of extra trips when the thing is only half full.
My idea was to rip all the guts out of a pager except for the little motor
and the buzzer. The idea would be that at 70% full it would vibrate for a
short time, at 80% for longer time at 90% for an even longer time and
continuously at 95%. The switch on the pager could select vibrate or
Buzz with a centre off position. All this is very easy.
What I need is something like a rubber band that upon expansion would change
it's resistance that we could strap with Velcro round the bag itself to give
an idea of how much the bag has expanded.
Does anyone have a good idea of what I could use for this ?
Justin Pentecost
To UNSUBSCRIBE, just send mail to:
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BEN (TEAM DBR)
http://www.geocities.com/temdbr
Do You Yahoo!?
Get personalised at My Yahoo!.
[noparse][[/noparse]Non-text portions of this message have been removed]
easier to measure the weight of the bag? Just a thought..
HTH,
Leroy
BENS ANTS wrote:
>
> 2 teminals in the Catheter, and when it is full it make a contact and sound a
buzzer
>tenner so I have little to lose by trying. The bags are like the ones you
>have when you are giving blood and when empty they are flat as they fill up
>they become oval shaped. You are correct of course the circumference does
>not change The idea I had was to have a flat plastic (ridged) strip which
>Velcro's to one side. This plastic strip has two lugs either end. The
>sender would hard mounted at either end and have a wide elastic in the
>middle.
>
>There is one very important point here. The resistance that the sender
>gives must never be so great or springy that it will force urine to flow
back up the tube.
Very possibly there are medical people on this list - I am not one but
I am familiar with catheters. It might be a good idea to have some
sort of fail-safe mechanism in place, just in case the system doesn't
work the way it's supposed to. Especially as you stated that the person is
paralyzed and may not be conscious of damage being done.
Reg Neale
I am familiar with catheters. It might be a good idea to have some
sort of fail-safe mechanism in place, just in case the system doesn't
work the way it's supposed to. Especially as you stated that the person is
paralyzed and may not be conscious of damage being done.<
Simply the fact that it is any kind of medical equipment creates problems,
I have no idea what happens in other parts of the world but here certainly
no piece of medical equipment can be modified without all sorts of approval
(Hence someone else's suggestion of putting contacts in the bag is a total
No No). And also (as pointed pointed out by someone else again) there is
no proper data for this device, and how repeatable the results are is a
matter of conjecture and testing.
I spoke to one of the social workers and today I picked up the full setup
for this bag. Basically it's like two garter's and the bag goes between
them. The idea of making an elastic hanger is certainly possible.
Yesterday I was at my Parents house and my father and I were (much to the
amusement of the rest of the family!) experimenting with this setup in the
garden.
As far as risk goes my father (who's a retired Surgeon) says there is none
because these things are intrinsically safe anyway. The only danger is of a
puddle on the floor (which is to be avoided at all costs but it does mean
that we can do this, because if there was any MEDICAL risk I would drop the
project straight away.
The reason the thing came up in the first place was because the present
"system" which is a time based system results in a failure a week.
Justin
I am assuming that the person for whom this sytem is designed is in a
wheelchair...please disregard my comments that follow if the assumption
is wrong.
I have found that there are lots of places to attach things to the
frame of a wheelchair. I think it would be relatively easy to hang the
catheter bag on a lever arm connected to the frame of the chair. When
the bag reaches a predetermined weight, it pulls the lever arm down and
makes (or breaks) an eletrical or optical contact. See the terrible
ASCI drawing below:
_____________(electrical contact)
[noparse]/noparse
[noparse]/noparse
>>>>>>>>O>>>>>>>>>>>>>>> (lever arm pivots around the 'O')
!
!
!
[noparse][[/noparse] BAG]
[noparse][[/noparse] ]
This would not entail any modification to the urine collection system,
and you could have the time system as a back up. If it is a power
chair, you could also tap off the battery system for the power. I have
made many modifications to wheelchairs for things like this- if you
need additional help, feel free to contact me off-list.
Peter
FDA approval to market for medical devices requires safety and
reliability documentation, even for items appearing intrinsically safe.
The trade journal Medical Device & Diagnostic Industry <
www.devicelink.com/mddi > is a good resource for safety issues, FDA
regulations, and biomaterials info. Underwriter Laboratories web site
has additional standards and safety info < www.ul.com >.
Dennis
Original Message
From: Justin Pentecost [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=VIvlwqCUrh3CT4dtmpLLjZxmD7ulNhNNNffc-ZWjN_I7jDK8g1qoTLA17z9KzR4AwuKvifm_]justin@k...[/url
Sent: Sunday, March 31, 2002 9:32 PM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Expansion and variable resistance ...
>Very possibly there are medical people on this list - I am not one but
I am familiar with catheters. It might be a good idea to have some sort
of fail-safe mechanism in place, just in case the system doesn't work
the way it's supposed to. Especially as you stated that the person is
paralyzed and may not be conscious of damage being done.<
Simply the fact that it is any kind of medical equipment creates
problems, I have no idea what happens in other parts of the world but
here certainly no piece of medical equipment can be modified without all
sorts of approval (Hence someone else's suggestion of putting contacts
in the bag is a total
No No). And also (as pointed pointed out by someone else again) there
is
no proper data for this device, and how repeatable the results are is a
matter of conjecture and testing.
I spoke to one of the social workers and today I picked up the full
setup
for this bag. Basically it's like two garter's and the bag goes
between
them. The idea of making an elastic hanger is certainly possible.
Yesterday I was at my Parents house and my father and I were (much to
the amusement of the rest of the family!) experimenting with this setup
in the garden.
As far as risk goes my father (who's a retired Surgeon) says there is
none because these things are intrinsically safe anyway. The only
danger is of a puddle on the floor (which is to be avoided at all costs
but it does mean that we can do this, because if there was any MEDICAL
risk I would drop the project straight away.
The reason the thing came up in the first place was because the present
"system" which is a time based system results in a failure a week.
Justin
Dennis, you are, of course correct. There is a vast and all but
incomprehensible regulatory quagmire that governs the marketing of
medical devices. I know: it is, unfortunately, a large part of my life.
But, the pertinant sections of 21 CFR that deal with "accessories for
urine collection systems" puts many such devices in the exempt
catagory. Also, as this would be a prototype of an exempt device, it
would probably also be covered as an investigational new device.
Finally, there are devices on the market that this device would qualify
as "essentially identical to." For complete assurance of lack of
liability, you will need a lawyer, and a thorough review of the
relevant parts of 21 CFR. I can do the regulatory review, but it would
Thanks for clarifying this. Your message ended abruptly, leaving us in
suspense.
Dennis
Original Message
From: Peter Charles [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=d__CP6Pmd2cTzu1JopU9Y0OVtKUUQSPiG00cF6_6LeoSgTE76Yf-lCuY8ohjYjYgTC95eGJiEwxb4GYL8NVW]pcharles@m...[/url
Sent: Monday, April 01, 2002 4:14 PM
To: basicstamps@yahoogroups.com
Subject: Re: RE: [noparse][[/noparse]basicstamps] Expansion and variable resistance ...
Dennis and Justin-
Dennis, you are, of course correct. There is a vast and all but
incomprehensible regulatory quagmire that governs the marketing of
medical devices. I know: it is, unfortunately, a large part of my life.
But, the pertinant sections of 21 CFR that deal with "accessories for
urine collection systems" puts many such devices in the exempt
catagory. Also, as this would be a prototype of an exempt device, it
would probably also be covered as an investigational new device.
Finally, there are devices on the market that this device would qualify
as "essentially identical to." For complete assurance of lack of
liability, you will need a lawyer, and a thorough review of the
relevant parts of 21 CFR. I can do the regulatory review, but it would
To UNSUBSCRIBE, just send mail to:
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Sorry about the truncated message...it happens often when emailing from
my laptop. I was only going to point out that the regulatory aspects
of these issues were the only part of my job that I really dislike, and
that a thorough investigation would actually cost real money. I could
do a quick and dirty search of the Code of Federal Reg's, but the
important issues would need to be addressed by an attorney. It's more
of a personal liability issue, as I don't suspect that Justin is
planning to market and manufacture this device. Thus all of the
GLP/cGMP issues shouldn't really concern him. If anyone is truly
interested, I would recomend a trip to the USFDA-CDRH website
(www.fda.gov/cdrh/devadvice). Welcome to my nightmare...
I am happy to consult, officially or unofficially, if Justin (or
Dennis, or anyone else) needs to pursue Federal regulations and issues
of GLP/GMP compliance as it pertains to biomedical devices (even 21 CFR
part 11, which should have the "Abandon all hope, ye who enter here..."
disclaimer!). Contact me off-line, though.
Good luck.
Peter C. Charles, PhD
> Peter,
>
> Thanks for clarifying this. Your message ended abruptly, leaving
> us in
> suspense.
>
> Dennis
Thanks very much for the information, As Peter says I'm not even thinking of
making more than one [noparse]:)[/noparse] It's really nice to know that this list has so
much Knowledge and experience.
What I am reliably told is that this does not qualify as a "medical device",
because it does not perform any medical function (how you describe that I
have no idea) and does not require the modification or interference with any
device supplied by the NHS. It therefore falls into the category of a
"Living Aid" and the regulatory requirements for this are the same as any
other consumer product.
I have now worked out exactly how this is going to work. It's more
complicated than it may at first seem because of rather special
circumstances of the end user. The user is a teenager who was injured in
motor accident. She lives at home and goes to a regular school, the
fact that she uses a catheter is something she likes to keep very discrete.
The bag is therefore always under her clothes. It's very simple with a
single wide breathable "Garter" at the top with a press stud on it (a bit
like a big earthing band) and then a piece of elastic (about an inch wide)
which has a plastic hook on it on which the bag rests. What I now know
is that this arrangement is in fact made by her mother because she could not
find anything else. (most of these sort of arrangements are made for
hospital or care home use, and certainly not for teenagers). It's
therefore suddenly become very simple[noparse]:)[/noparse] All I have to do is get her
mother to make a new strap incorporating the variable resistance device.
The reason I'm using a basic stamp at all is because we want this device to
act in a similar way to a bladder. I.e. at say 70 - 90% it give a gentle
and discrete reminder (i.e. a vibrate alarm getting gradually longer as it
fills up) every couple of mins or so. and past 90% it becomes more urgent.
(Does this sound familiar?). Originally I was going to use an old British
Telecom pager with the guts stripped out. I've dropped that idea and am
using a plastic box with a PP3 compartment and a belt clip. Apparently it
HAS to be pink [noparse]:)[/noparse] and I'm running it over to a friend of mine who's going
to paint it [noparse]:)[/noparse]
Justin Pentecost
Focus Puller London
Very cool use for this technology. I particularly like the way it will
mimic the natural bladder response (ie, a sliding urgency scale).
Quite an elegant solution to this young woman's problem.
Please keep us posted on how it works out.
Best regards,
peter
Definitely an interesting and worthwhile project. Regarding a vibrating
alarm, Marlin P Jones & Assoc Inc < www.mpja.com > sells a very small
pancake DC motor with off center weight used in cell phones: diam: 14mm,
thickness 3.5 mm, cost $1.50 US.
Dennis
Original Message
From: Justin Pentecost [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=TgcA5nKfPIH0RwdEBeFFeQtMPCvqf0mfVQKRQiwnXMJwVwbk-x12aI4ARcugYbGVlah5TH6UXGnD]justin@k...[/url
Sent: Tuesday, April 02, 2002 1:08 AM
To: basicstamps@yahoogroups.com
Subject: RE: [noparse][[/noparse]basicstamps] Expansion and variable resistance ...
< deleted >
The reason I'm using a basic stamp at all is because we want this device
to act in a similar way to a bladder. I.e. at say 70 - 90% it give a
gentle and discrete reminder (i.e. a vibrate alarm getting gradually
longer as it
fills up) every couple of mins or so. and past 90% it becomes more
urgent.
(Does this sound familiar?). Originally I was going to use an old
British
Telecom pager with the guts stripped out.
< deleted >
not regulate medication or monitor the individuals vital signs. A pushbutton
to a buzzer is for alerting assistance required. This is an automatic
pushbutton.
Steve
Original Message
From: "Dennis P. O'Leary" <doleary@h...>
To: <basicstamps@yahoogroups.com>
Sent: Monday, April 01, 2002 12:20 PM
Subject: RE: [noparse][[/noparse]basicstamps] Expansion and variable resistance ...
> Justin,
>
> FDA approval to market for medical devices requires safety and
> reliability documentation, even for items appearing intrinsically safe.
> The trade journal Medical Device & Diagnostic Industry <
> www.devicelink.com/mddi > is a good resource for safety issues, FDA
> regulations, and biomaterials info. Underwriter Laboratories web site
> has additional standards and safety info < www.ul.com >.
>
> Dennis
>
>
Original Message
> From: Justin Pentecost [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=zx7FEGeSLR-GC69dr_XCrgRd287UxIYyD8LReqPG3PGpiBkTNrj6p45Meq0etbHBnEsGSkEf_A]justin@k...[/url
> Sent: Sunday, March 31, 2002 9:32 PM
> To: basicstamps@yahoogroups.com
> Subject: [noparse][[/noparse]basicstamps] Expansion and variable resistance ...
>
>
> >Very possibly there are medical people on this list - I am not one but
> I am familiar with catheters. It might be a good idea to have some sort
> of fail-safe mechanism in place, just in case the system doesn't work
> the way it's supposed to. Especially as you stated that the person is
> paralyzed and may not be conscious of damage being done.<
>
> Simply the fact that it is any kind of medical equipment creates
> problems, I have no idea what happens in other parts of the world but
> here certainly no piece of medical equipment can be modified without all
> sorts of approval (Hence someone else's suggestion of putting contacts
> in the bag is a total
> No No). And also (as pointed pointed out by someone else again) there
> is
> no proper data for this device, and how repeatable the results are is a
> matter of conjecture and testing.
>
> I spoke to one of the social workers and today I picked up the full
> setup
> for this bag. Basically it's like two garter's and the bag goes
> between
> them. The idea of making an elastic hanger is certainly possible.
> Yesterday I was at my Parents house and my father and I were (much to
> the amusement of the rest of the family!) experimenting with this setup
> in the garden.
>
> As far as risk goes my father (who's a retired Surgeon) says there is
> none because these things are intrinsically safe anyway. The only
> danger is of a puddle on the floor (which is to be avoided at all costs
> but it does mean that we can do this, because if there was any MEDICAL
> risk I would drop the project straight away.
>
> The reason the thing came up in the first place was because the present
> "system" which is a time based system results in a failure a week.
>
> Justin
>
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>
>