by LoganP2 @ instructables.com:
The GPS tracking device is composed of a microcontroller, GPS module, cell module, and batteries all housed in a 3D printed case. The microcontroller is programmed to communicate with both the cell module and GPS module. When the GPS module is not within a user-specified boundary, the device will send a text message alert. We made a device that can track people suffering from Alzheimer’s and Dementia could greatly benefit the quality of life of both that person suffering and the caretaker.
GPS Tracker for Alzheimer’s Patients – [Link]