Home Gadget monitoring system - RFID instead of LEDs

Summary: The idea of the porject is to replace the LEDs in technical deviced with RFID chips. Then by using a centralized RFID Reader I can monitor the status of the technical devices.

Approache 1: active - active
I replace the LED with an active RFID chip[1], then I had a default signal to detect and when the LED would be activated, the signal has to change. From the easy standpoint it should be able to detect the change in power which is supplied by the change of signal intensity.

Approache 2: active - passiv
I use an active RFID chip[1] but instead of powering it I use an active rfid reader. When the LED is switched on the RFID chip is powered, which means it does not have to be activated by the reader first, which reduced the response time. So in active state I have a much faster response than in passive state. I am just not sure about the distances which is the reason why I currently think approach 1 is the better choice.

Approach 3: two signals
I use two RFID chips[1] to replace one LED, an with a transistor I detect the status of the LED and either activate one or the other RFID chip.



Questions:

• Which approach do you think is more realistic ? Obviously the approach 3 is simpler but on the other hand costs around twice as much and I plan to apply these sensors to quite a few of my gadgets.
• Do you know any similar projects ? I searched the web but somehow did not find any.

[1]: http://htrfid.en.alibaba.com/product..._RFID_Tag.html