X-Message-Number: 28318
From: "Jordan Sparks" <>
Subject: Mechanical CPS
Date: Tue, 15 Aug 2006 22:20:23 -0700

Still trying to come up with a design for my mechanical CPS device.  I had
pretty much settled on duplicating the function of the thumper when someone
suggested that a chest band would be preferrable. AutoPulse: www.zoll.com .
From descriptions I've read, the band contracts quite suddenly and
forcefully.  Could be a geared motor or it could be a solenoid.  Theirs is
$15,000, but that surely includes expensive batteries, FDA approval, retail
markup, marketting, etc, etc.  So a homemade version couldn't be more than a
few thousand.   For instance, I'd go with really cheap batteries, and just
plug into a wall or vehicle outlet for most of the trip.  Even assuming a
simple solenoid, there's a significant complexity to submersing electronics
in water.

But why this new alternative?  Well, the main complaints with the Thumper
seem to be the noise, bulk, and complexity.  Unfortunately, I don't think a
homemade band device is going to be all that quiet, sleek, or simple.  I
think the basic concept of the Thumper is perfect.  Size and weight can be
improved, especially if we do without the decompression portion of it.  For
example, imagine a fist sized box that gets strapped to the top of the chest
and hooked to an air line.  A fist-sized cylinder has enough power to
compress a few inches.  You don't have to have that big metal frame arching
over the top of everything.  And there must be cylinders and valves that are
quiet.  Or mufflers or something.  The valving can all be underneath in a
heavily soundproofed box.  It will be controlled electronically.

So, moving the actuator under the patient might remain a possibility in the
future, but I'm still going to have my first version be top-mounted
pneumatic.  There could still be a band to strap it on to the patient, and I
think it could be more compact than the AutoPulse except for the requirement
to hook it up to a tank of O2.  I might look into paintball canisters or
something along those lines for a very portable version.  Time to order my
(fairly expensive) cylinder and hope I get it right the first time.

Jordan Sparks

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