Implants

No, not those implants.
I'm talking about cybernetic implants. It's a controversial issue, to say the least. But if you think about it, people have now been getting artificial devices implanted in their bodies for a variety of medical reasons for a long time. The first pacemaker was put into a patient in 1958. It was designed by Canadian (yay!) Dr. John A. Hopps.

http://archives.cbc.ca/on_this_day/10/08/

So, keeping your heart going, I'd say, is a good reason to have an artificial device in your body, if you need it. But what about other applications? Well, let's see:

1. other organ transplants are still foreign objects being put in the body, so that works.
2. Artificial hips have been around since the 1940s, with modern technology dating from the 1970s, so that works.
3. Artificial shunts (tubes used to drain fluid in the body) have been around since the 1950s.

So as we can see, yes, there is a medical precedent for devices implanted in the human body.

So what about non-medical devices?

I know what you're thinking.

Anyway, one of them that I think would be a good idea would be an RFID (radio frequency) tracking device. It would be implanted under the skin in a person's arm, and allow other people with an RFID tracker to be able to pinpoint the location of that person. The tracking devices would be given only to parents or guardians of the person with the chip, and police/fire/paramedics who need to reach them.  Each person with an implant would have their chip tailored to transmit on a very, very specific frequency. Radio waves can have frequencies anywhere from 3 Hz to 3 Thz, providing plenty of frequencies for each person who gets a chip. Each tracking device would also have a biometric access measure, so that unauthorized individuals (say a criminal, trying to find a child to abduct) would not be able to use the device.

So what to do if there is signal interference?

Quantum entanglement might offer the possibility of getting around EM interference. If we can perfect a tracker-to-transmitter that uses that principle, it might be impossible to interfere with that signal.

So, let's see what you all think.