Does anybody activate the theft sensor in the Stores?

[edielcs]

I notice that when i enter or leave to some stores the theft sensor activated I think is my hip, but the rare that it happen like 3 weeks ago, and my surgery was in april 2008

[wayne-0]

I haven't noticed but tomorrow I am going to see if I can activate at least 1 store sensor. I will let you know how it goes.

Wayne

[Bionic]

Anti-theft sensors are usually more than simple metal detectors.  Think about it.  If they were metal detectors, our watches, jewelry, coins, and even shopping carts would set them off.  There are different kinds of anti-theft devices, but they all use some form of encoded tag that can be read by an antenna array.  When the antenna picks up an encoded signal from a tag, it sounds an alarm to indicate that the tag has not been removed or deactivated.

See http://www.thehowandwhy.com/Security.html .

In contrast with these, the sensors used in airports, many schools, and federal buildings are simple metal detectors.  They're not looking for tagged merchandise but rather guns and knives.  Those are the places where we're likely to have problems.

[fenceman]

Maybe you are a amnetic kleptomaniac and don't realize it. . 

I am becoming well know to the TSA at our local airport but I have never set-off the theft sensor.

[edielcs]

hey bionic  i  reading the web side that you post, and I understood that to activated the sensor it has to be a magnetic field, that mean that my hip becomes magnetized, because for the first 6 months i didn't activated the sensor, and  the lasts weeks i started to activated the alarms only in some storers( walmart, blockbuster, auto zone, lowes) is stores uses a anti-theft sensor called sensormatic
any one know how my hip could become magnetized .my  only concern that i have is that  if I  could have any complication with my hip.

[Bionic]

Cobalt is ferromagnetic, meaning it can be permanently magnetized: http://en.wikipedia.org/wiki/Cobalt .  It is not clear that cobalt-chrome-molybdenum is, however.  That property might be significantly diminished in the alloy.

Assuming your implants are magnetizable at all, they would have to be subjected to a strong magnetic field to get that way.  Have you been in an MRI machine lately?

Even assuming your implant has become magnetized, it would take more than that to trigger a Sensormatic system.  Sensormatic tags are acousto-magnetic: http://en.wikipedia.org/wiki/Sensormatic .  They work by changing size when exposed to an oscillating magnetic field.  A sudden change in size causes them to emit a pulse that can be "read" by an antenna:  http://www.thehowandwhy.com/Security4.html .

Although it might be possible for your implants to become magnetized, it is not possible that they would change size suddenly in response to an applied oscillating magnetic field.  They are simply too rigid.

It might be possible (although really unlikely) that your implants might be interacting with something else to trigger the alarm.  Acousto-magnetic tags require a "bias magnetic field" to operate.  Conceivably, your implants could provide this, while some other material, say, your cell phone or PDA in your hip pocket, might fall within that field and respond to the oscillating field in a way that triggers the sensor.  It's pretty far fetched, however.

Is it a health hazard?  Probably not.  In the worst case you have a magnet inside your body.  So what?  No one has ever shown that magnets are a problem.  Some people believe magnets have magical healing powers: http://en.wikipedia.org/wiki/Magnet_therapy .

There's even a team of doctors who deliberately put magnets in hip implants to vacuum up the metal debris: http://www.dailymail.co.uk/health/article-510987/The-new-magnetic-hip-lifetime.html

[Bionic]

If you hadn't seen this already, MRI's are apparently safe after hip resurfacing.