Someone beat me to it but I was also going to mention the Specialized ANGI. I was reading about it and looks like it's exactly what you are looking for if you want a device on yourself or your bike. Also, someone mentioned the free RoadID app. It uses your phones gyro to detect falls. This is what I use and it works really well. It sends emails to the people you have in your contact list as well as the coordinates of where you are at. It also allows you to dismiss the alerts in the event of a false alarm. Probably not as good as the ANGI but it's free and works with iPhones and Andriods.
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HCFR Cycling Team
Ride Safe ... Ride Hard ... Ride Daily
2017 Colnago C-RS
2012 Colnago Ace
2010 Giant Cypress