Electronics patent of the month: Method for determining RFID tag tampering
GB Patent no: 2462964
Granted to: Guard RFID Solutions
Every parent dreads their child being ill and having to spend time in hospital. Thanks to a recently granted patent, parents can sleep more comfortably at night in the knowledge that they can be less concerned about one aspect of a child’s stay away from home.
Patent no. 2454987 was granted on 5 September 2012 and describes a tracking technology developed by Canadian company, Guard RFID Solutions. RFID tags are often used to track a person or object, but in order to work effectively it is also necessary to be able to detect when such tags have been tampered with.
Typically, in a paediatric ward of a hospital, children may be provided with an RFID tag which prevents the child being removed from the unit by engaging door locks and triggering alarms. For such applications it is important to ensure that the tags cannot be removed without the system detecting this act. Existing tags attempt to address this issue, but with some drawbacks.
One method currently used is “cut-band” detection, where the band holding the tag is electrically conducting, so that if it is cut the increase in resistance is detected and the alarm is triggered. A drawback of this technology is that, in practice, such bands can be removed from a patient’s wrist relatively easily, particularly in the case where a child has lost weight and their wrist has become thinner. Also, cut-band technology can be defeated by using a conductor to connect the two cut edges.
A second approach that has been used in the past is capacitance sensing, whereby a change in capacitance is detected when the tag is placed next to and removed from a patient’s body. A drawback of this approach is that the change in capacitance is actually quite small and can be difficult to detect.
In order to overcome these problems, Guard RFID has developed a new tactic by including both a visible light sensor and an infra-red sensor in the tag, along with a processor, power source and wireless network interface. The tag is covered by an enclosure which is partially opaque so as to prevent ambient light falling on the visible light sensor once the tag has been attached to a patient. In addition, the infra-red sensor is used to detect a change in infra-red radiation.
The human body has a natural temperature which causes it to radiate energy in the infra-red spectrum so that when the tag is adjacent to the body, the infrared radiation is constant or changes slowly with fluctuations in body temperature. However, if the tag is removed then the infra-red radiation level will drop dramatically, thereby enabling easy detection of tag removal and providing an improved safeguard for young and infant patients.
Michael Jaeger is a patent attorney at leading UK patent and trade mark attorneys, Withers & Rogers LLP.
Previous Electronics Patent of the Months:
Electronics patent of the month: Aiding pilot choice of flight path modes
Electronics patent of the month: Multiple radio transceivers sharing an antenna
Electronics patent of the month: Sensors to avoid driver blindness