The Continua Health Alliance recently selected the 2.4-GHz Bluetooth Low Energy (BLE) and ZigBee Healthcare protocols for Version Two of its Interoperability Design Guidelines. Because of its popularity in mobile phones, BLE likely will become the norm for home healthcare applications. On the other hand, Steve Dean of TI says, ZigBee is likely to dominate some clinical settings for patient and asset tracking.
Then there are proprietary protocols like ANT from ANT Wireless, a division of Dynastream Innovations. ANT is an ultra-low-power wireless 2.4-GHz protocol for healthcare and fitness monitoring applications. The company says that ANT-power nodes can operate for years running on coin-cell batteries compared to months for other types of batteries. Designed for reliable and flexible data communications, ANT is immune to cross-talk interference.
Interference-free medical monitoring is a major issue for design engineers and medical equipment OEMs. Medical monitors and transceivers must be designed to emit low energy levels without interfering with other ambient signals. Wireless and wired transmissions must meet stringent U.S. Food and Drug Administration (FDA) safety and reliability requirements. Moreover, transmitted data must meet strict privacy requirements for both patients and medical providers.
Nordic Semiconductor employs the ANT protocol in its nRF24AP2 eight-channel wireless transceivers. More recently, the company has begun sampling its nRF8001 BLE chip (Fig. 7).
According to ABI Research, just over 2.5 billion BLE chip sets will be shipped by 2014 in a market that will grow at compound annual growth rate (CAGR) of 78%. The growth of the chip sets will mirror BLE’s two different implementations, dual mode and single mode, with single-mode chips implemented first.
Freescale Semiconductor has endorsed the ZigBee Healthcare protocol. With a market share around 60%, Freescale is the leading provider of ZigBee-based transceiver chips, which conform to the IEEE 802.14.5 standard. It also is a leading supplier of sensors, embedded processors, and power-management devices, all used extensively in home healthcare applications. These include pulse oximeters, blood glucose meters, insulin pumps, infusion pumps, blood pressure monitors, and personal monitoring products, such as activity monitors, gait sensors, and wearable panic alarms.
BODY-WORN NETWORKS
Efforts like those of the Continua Health Alliance are giving rise to the development of body-worn wireless sensor networks, also known as body-area networks (BANs) and personal-area networks (PANs). Such networks use inexpensive, very low-power, interoperable, and interference-free wireless sensors that connect to a real-time display like a watch and then to a home computer. From there, medical information can be sent over the Internet or even wirelessly to a medical provider.
“Wireless monitoring would allow healthcare authorities to maintain a high level of vigilance over the elderly while allowing them to remain in their homes as long as possible. This is a recipe for a dramatic reduction in costs and a happier patient,” says Alf Helge Omre, business development manager at Nordic Semiconductor.
At the IMEC Holst Centre in Lueven, Belgium, scientists are developing a BAN for arousal monitoring by measuring four physiological body parameters to assess a person’s emotional state. The BAN is being developed within the Centre’s Human++ program. It uses sensors attached to a strap that goes around the person’s body.
Detected body data is wirelessly transmitted to a PC acting as a basestation for further analysis by medical or other personnel in the medical and gaming fields. IMEC’s scientists believe this can be of great value for a variety of applications in the entertainment and medical fields.
A mix of hardware and software built into everyday items such as clothing and bedding to monitor and alert cardiac patients about their conditions is part of the European Union’s 14-million Euro HeartCycle project. While such a system of networked sensors and monitors would not be a substitute for face-to-face meetings between patients and doctors, it would alleviate that need by requiring fewer such meetings.
The system detects and remotely monitors small changes in the heart’s behavior that can be addressed in due time before these changes become more serious. Led by Philips Research in Germany, the project involves 17 other academic and industry organizations, including Finland’s Clothing Plus Oy, Philips Electronics NV in the Netherlands, and Medtronics Iberica SA in Spain.