How Can I Build a Portable "Dead-Man's" Switch?
An anonymous reader asks: "I'm a widower caring for my very disabled child. I have family who check in on me often, but not reliably, and not every day. How can I rig up a 'dead-man's switch' that will alert family or emergency services should something happen to me, so that my child can be cared for? Her medical needs are significant enough that being alone for even an hour could be fatal for her. We do occasionally get out of the house, so a GPS type cellphone and a heart-rate monitor watch would seem to be the ticket, but how to link the two and get the desired dialing behaviour?"
If we are talking about a serious system here, you aren't going to be able to do this yourself. Just for starters, think about how complicated this would be if you decide to have a shower. You will have to deactivate the whole shooting match and then get it all back up and running again afterwards. Of course, if you slip in the shower, you're screwed. There are already solutions out there that you can sign up for. One that I have seen is a pendant you wear around your neck that has a button on it. One push, and your relatives are notified by phone. Or, fail to push the button on a regular basis and a phone call comes from the monitoring service, who can also dispatch 911, etc. Finally, at the risk of being harsh, if you truly believe you may die suddenly with no notice at any time, you seriously need to reconsider your current care arrangements. You do not strike me as qualifying to care for some with the needs you imply in your question. Please take this as honest advice, not a flame.
Based on the information we're given, I think the only compassionate answer is "don't do this yourself." If a person's life depends on the reliability of this solution, trying to come up with a clever hack is just plain irresponsible. In that case, you really need to buy a tested off-the-shelf solution.