Conclusion So far the system works as designed. One important item to watch out for is to make sure any rules created will bypass a ‘silent’ time for the voice announcements during the night time (yes this was found out the hard way) so these alarm messages are always sure to go through!
This circuit is just a prototype but wound up being the first production unit as well. If this were to be a ‘final’ version, a more simple circuit should be incorporated for the Elk-960’s portion and included with the piezo’s sensor’s circuit and incorporated on just one printed circuit board.
I was also thinking it might be better to use multiple smaller speakers across the length of the cradle to eliminate the problem I had of the Dexcom remote not coming into contact with the center (initial speaker’s location) of the mount.
Another consideration is powering the system. The optimal way is to power the unit via the Elk M1’s 12 volt system, just as you would any powered peripheral as it has a battery backup. I did not do this as I ran out of wires and opted for a good 12 volt regulated wall wart instead. I do plan on fixing this once my friend runs another wire bundle to this bedroom. The AC input feed to his Elk system is also provided via an APC UPS, thus creating additional backup time.
One problem that was noticed was the working distance between the remote sensor (on the body of the person monitored) and the remote unit seems to slightly decrease, due to the aluminum cradle. A quick work around was to lay the Dexcom remote down on its front face when placing it in the cradle for the night. A pre made plastic box might be the way to go instead of using aluminum, but additional testing would of course be needed to insure similar sensitivity of the transmitting vibrations could still be picked up via the piezo speaker.
Worries about this possibly becoming a ‘life saving’ device were also considered. Testing over several weeks, and the addition of powering the device from a battery backed system were performed and though it can not provide a 100% guarantee, it was certainly better than the lack of any kind of monitoring system.
Overall through almost a half-year of testing, the performance of this system has exceeded initial expectations. The unit has not been modified since its initial deployment, and has thus far adequately detected when the remote Dexcom monitor vibrated due to a glucose reading being out of range.
It provides the missing detection element needed during the night time when people are sound asleep.
I would be interested in hearing opinions of our forum members that happen to use a Dexcom monitor for their diabetes blood sugar level alarms. HERE is the link for the discussion/forum.