My mother, age 80, has the disease. Is there a passive radio frequency identification system available that I could install at the doors of her home to alert me, via mobile phone, if she goes outside? I live 40 miles away, and am not always there in the event of an emergency.
There are active RFID-based real-time location system (RTLS) solutions for tracking Alzheimer's patients within hospitals (see BlueTag Patient-Tracking Comes to North America). Some medical facilities have also utilized passive ultrahigh-frequency (UHF) RFID tags (see RFID Gives Dementia Patients Their Freedom). There is not, however, any system sold specifically for home use—at least, not that I am aware of.
You could buy the components and cobble together a simple system that would do the job, for only a few thousand dollars. You would need to purchase passive UHF transponders that could be sewn into her clothing. You could buy passive UHF readers to install in the doorways of her home, and you would need to connect them to the Internet and then set up some software that would trigger an alarm if she passed through a doorway. If you are not a programmer, you could probably find a college student who could do this for you.
The hardest part of installing such a system would be ensuring that you would not read tags in your mother's clothing every time she walked close to a door but did not go out. You could try employing a reader embedded in a mat outside the door. Embisphere offers a mat for retail stores that might work if you were able to protect it from the elements. You might also consider setting up a web camera; if you received an alert that your mother had passed through a doorway, you could check the camera to see if she had really left the house.
—Mark Roberti, Founder and Editor, RFID Journal