In our increasingly wireless world, the air is full of electromagnetic signals carrying data from one place to another. While these new technologies advance our options in security, commerce and entertainment, they also produce potential interference that may cause concern for people with implanted medical devices.
One source of potential interference is the electronic article surveillance (EAS) systems that help retailers, libraries and other establishments prevent theft and track inventory. Also, early signs suggest potential concerns from the radio-frequency identification (RFID) systems that are now coming into more widespread use.
Georgia Tech's EAS/Medical Device E3 Test Center helps manufacturers improve compatibility between implantable medical devices and systems that radiate electromagnetic energy. The Center, which has focused on EAS systems for more than a decade, has recently expanded its operations and facilities to test new types of security and logistical systems including RFID.
"EAS systems may cause medical devices to do anything from shutting down to invoking therapy at the wrong time not a good thing if you're wearing a defibrillator, which is supposed to shock the heart when needed," explained Ralph Herkert, manager of the Center, which is part of the Georgia Tech Research Institute (GTRI).
Typically, manufacturers use filters to reduce electromagnetic interference, but medical devices pose special challenges. The operating frequencies and modulation characteristics of EAS systems and tag deactivators can fall in the same frequency band as biological signals, such as the heartbeat. Filters would not only eliminate the EAS signals but also the very signals that medical devices are designed to detect.
"Instead of filters, medical device manufacturers must deal with the interference in other ways, such as refining their firmware algorithms," Herkert said.