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Wear your heart monitor on your sleeve

-December 09, 2012

This article is part of EDN's Hot Technologies: Looking ahead to 2013 feature, where EDN editors and guest contributors examine some of the hot trends and technologies in 2012 that promise to shape technology news in 2013 and beyond.

Just when you think ICs can’t get any smaller, someone releases a more-compact, lower-power, better-performing solution, usually on a monolithic die. Analog front-end and microelectromechanical-system devices have led the pack in miniaturization innovation this year, and one result has been a spate of health and wellness monitors that users can wear as unobtrusive accessories.

A case in point is an e-compass enabled by MEMS technology from STMicroelectronics (Figure 1). The e-compass, or “geomagnetic module,” integrates a three-axis digital magnetometer with a three-axis digital accelerometer, used for tilt compensation, in a single package.


Figure 1 Runners can strap an e-compass, built with STMicroelectronics MEMS
technology, on a wrist.

EEG (electroencephalography) analog front ends are another example. Texas Instruments designed its ADS1299 AFE to help manufacturers of extracranial-biopotential measurement equipment reduce board space, design time, and cost while improving performance. The AFE can be used in EEG equipment to monitor bispectral index, evoked potentials, and event-related potentials to aid in diagnosing such conditions as brain injuries, strokes, and sleep disorders.

Among the EDN Hot 100 products in the analog category this year are heart- and fitness-monitor AFEs from TI (AFE4300) and Analog Devices Inc (AD8232). These and other AFEs are meeting the growing demand for fixed, portable, and even wearable devices that provide vital-sign measurements for athletes in training, users of home fitness equipment, or those engaged in remote health monitoring.

ADI’s AD8232 for ECG applications eliminates the need for a right-leg drive lead so that a single lead can be used to monitor heart rate (Figure 2). Integrated filters for removing line noise and other interference improve performance. A multipole integrator rejects electrode offsets to maintain large dynamic range on an internal instrumentation amp. Operation on a single, 2 to 3.5V supply, directly from a battery, enables portability.


Figure 2 ADI’s heart-monitor AFE targets applications ranging from professional health care to personal fitness.

Wearable medical devices are becoming increasingly transparent to the user. The DuoFertility monitoring system (Figure 3), built with technology from Microchip Technology, comprises the company’s small PIC16 MCU-based sensor, containing a temperature monitor and wireless transmitter, that is worn under the arm; a handheld reader that houses a wireless receiver, temperature monitor, and PIC24 MCU; and PC-based analysis software. The combination lets the user monitor her fertility cycle without requiring her to take her temperature every day.


Figure 3 The DuoFertility monitor, bottom, is worn under the arm; temperature data is sent to the
handheld reader, top (courtesy Microchip).

Also watching:

  • Bluetooth Smart’s arrival. Developments in low-power wireless technology have hastened the advent of Bluetooth Smart ultralow-power portable devices. Implementing a single-mode, low-energy Bluetooth v4.0 dual-mode radio, the sensor-type devices run on button-cell batteries and typically are built to collect a specific piece of information—functioning, for example, as a heart-rate monitor or pedometer. An EDN Hot 100 product from a partnership between Stonestreet One and Freescale Semiconductor enables a turnkey radio module to hasten time to market for ultralow-power health-care devices.
  • MEMS’ proliferation. The past year saw an explosion of MEMS products, such as ADI’s ADMP504 microphone IC, Freescale’s Xtrinsic FXOS8700CQ six-axis sensor, and ST’s LSM303D e-compass module. All were among EDN’s Hot 100 products for 2012.

Read more of EDN's Hot Technologies: Looking ahead to 2013:

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