I'm an industrial designer with limited knowledge of electronics and was looking for some help. I am in the process of developing a dementia care product.

The idea is to manage the access residents have to each others rooms, currently they can wander in and out of rooms sometimes; sleeping in beds, trying on clothes and moving possessions around. This causes distress to residents confrontations between family and care home owners as well an extra work for carers and staff. It is not acceptable to lock the rooms as residents cannot use keys so it would be seen as an infringement of their rights.

I am considering using RFID UHF technology to trigger an electromagnetic door lock when a resident approaches their own door. Based on race timing systems, I am considering placing an antenna under the carpet in front of the door which reads a unique passive tag placed under the insole of all their shoes and slippers.

There are the following considerations:

  • Each tag must be very cheap ($0.50) and almost disposable, so no batteries.
  • Residents may not always wear their own clothes but tend to always wear their own footwear around the home.
  • This is not a security device and only intended to improve the current situation.
  • Dementia sufferers will not be able to wear bracelets or lanyards.
  • They will not be able to swipe a card.

Although RFID UHF technology appears to be the best solution, before I 'plough on' does anyone have ideas for a more appropriate technology?


This is probably going to sound all wrong but my cats are micro-chipped and they find it easy getting in and out of the chip-detecting cat-flap. So here's where I redeem myself, find a source of the chips and attack the problem that way. I'd be guessing but I can't see them being big prices. Apparently, they are the size of a piece of rice so fitting them in a shoe is going to be a minor problem.

It looks like the MCRF355 is a good candidate for the electronics heart. It's likely though that you'll be using 13.56MHz rather than UHF. Yes, they need to be passive to keep cost down and be unobtrusive. MCRF200 runs between 100kHz and 400kHz and maybe a decent solution too. This link also covers the MCRF250.

Humans too

  • \$\begingroup\$ gottaa hear what about your "cats are micro-chipped". \$\endgroup\$
    – Iancovici
    Aug 5 '13 at 18:21
  • 1
    \$\begingroup\$ @echad Not sure what you mean dude? \$\endgroup\$
    – Andy aka
    Aug 5 '13 at 20:40
  • 1
    \$\begingroup\$ I think this is a really interesting idea, but I also think there might be social resistance at chipping humans, as sort of addressed in that Wikipedia link. I can imagine the scrunched up daughter face in response to the statement "Your mom can move in just as soon as we chip her!" \$\endgroup\$
    – mikeY
    Aug 5 '13 at 20:48
  • \$\begingroup\$ @mikeY - we should be counting the days with dread!! Big bro gone Darwinian from Orwellian LOL \$\endgroup\$
    – Andy aka
    Aug 5 '13 at 21:07
  • \$\begingroup\$ @Andy aka, think I was lost in the context. Didnt understand what you meant when you said micro chipped cat \$\endgroup\$
    – Iancovici
    Aug 5 '13 at 22:22

I think RFID is common in similar situations. My mother's home issued me an RFID fob that works the front door so I get to come and go as I wish. If the patients could carry a fob or a card to tap a pad by each door, then you would be done.

Failing that, essentially disposable sensors in slippers might work. If the reader part was under the carpet and couldn't be moved, no exposed wires, nothing the cleaning staff need worry about, that might work.

Would staff wear the special shoes or have some other means of moving about?

Quite frankly it sounds to me like you are trying to be innovative as hell and still respect patient rights and dignities. So I wanted to say +1 for that.


RFID does provide an easy solution to your particular issue as it doesn't require easily-lost and fiddly keys or cards/codes.

However, I would be very wary of using RF-anything for "proper" security (EG preventing malicious intruders), the security holes are numerous and hacking this stuff is only getting easier and more popular.

In short - for keeping wandering old folks in their own rooms, great, but don't use it to secure the front door or the company safe.

For a few thoughts on the risks associated with RFID, and anything else IT/Security related, start reading here: Risks Digest.


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