Click here for the enhanced PDF version of this article

Targeting implanted pacemakers, nerve stimulators, drug pumps, and other implantable medical devices, Canada's Zarlink Semiconductor has developed an ultralow-power RF transceiver chip that delivers high data rates, low power consumption and unique wake-up circuitry. As a result, using this part, medical device manufacturers can design in-body communication systems that will improve patient care, lower healthcare costs, and support new monitoring, diagnostic and therapeutic applications.

Previous home health-monitoring systems required the patient to accurately position an inductive wand over the implanted device. By comparison, using Zarlink's medical implant communication service (MICS) technology, patient health and implanted device performance data can be stored in the implanted medical device's memory and wirelessly transmitted to a base station, without requiring patient intervention.

Data can then be forwarded over the telephone or Internet to a physician's office. If a problem is detected, the physician will schedule a patient follow-up visit where the two-way RF link can be used to interrogate and adjust implanted device performance.“As in-body communication systems evolve to support advanced diagnostics and therapies, it's critical that radio performance does not impact the battery life of an implanted medical device,” said Steve Swift, senior vice president and general manager, Ultra Low-Power Communications, Zarlink Semiconductor. “The ZL70101 transceiver offers unparalleled data rates and ultralow-power consumption performance in a highly integrated package, backed by Zarlink's established expertise in meeting the unique quality requirements for devices intended for human implant.”

To help conserve implanted medical device battery life, in-body communication systems transmit data on a scheduled or as-required basis. The ZL70101 transceiver incorporates a unique wake-up receiver that allows the integrated circuit to operate in an extremely low current 250 nA sleep mode. Communication is then initiated using a specially coded wake-up signal from the base station transmitter. The implanted medical device can also wake up the ZL70101 radio on detection of an emergency medical event. An emergency signal could then be sent to the base station, which in turn could directly alert paramedics. When in full operation, the ZL70101 typically consumes 5 mA of supply current. By using the high data rate with heavy-duty cycling, the average power consumed by the ZL70101 can be very small. The highly integrated ZL70101 system-on-chip includes a MAC. The MAC implements a communication protocol specifically designed for the requirements of high-reliability implanted medical devices, and is fully compliant to current MICS standards. The MAC protocol includes Reed-Solomon forward error correction together with cyclical redundancy check (CRC) error detection and retransmission to achieve an extremely reliable data link. The chip requires just three external components, excluding antenna matching, allowing device manufacturers to use board space savings to increase battery size and support advanced functionality while lowering overall system bill of material cost, noted Zarlink. According to the developer, the transceiver chip is available as implantable-grade wire-bondable die or in a 48-pin quad flat no-lead (QFN) package for the non-implanted base station applications. The chip is supported by a reference system and application development kit.

For more information, visit: http://products.zarlink.com/product_profiles/ZL70101.htm.