Here is another door sensor that works with SmartThings, ZigBee, and Wink to detect opening and closing of doors. The Centralite Micro Door Sensor notifies you of arrivals and departures. The sensor comes with a base that lets you magnetically mount it to a door or window.
The 3-Series Micro Door Sensor notifies you when your door or window is opened. It runs on CR-2450 battery. Costs under $30 at this time.