A hearty device

If exercising with a heart-rate monitor (HRM) is known as smart training within fitness circles, then working out with the Active 2 video game must be sheer genius because its HRM frees the user from wearing a chest strap.

By tracking your heart rate during a workout, professional trainers say, not only do you know whether you need to pick up the pace to reach your target heart rate, you ensure that you’re getting the maximum benefit from your exercise. Before the Active 2 from EA Sports came along late last year, the only reliable way to get an accurate reading during exercise was by using a device that’s been around since the early 1980s—a wireless HRM with a chest strap equipped with traditional electrocardiography (EKG) technology. After reading the electrical activity of the heart, the chest-strap model wirelessly sends the signal to an accompanying electronic device, such as a wristwatch, that displays the information.

As cool as that sounds, the chest straps themselves can be cumbersome for some users, and if they come loose during exercise, the signal is lost. Such limitations led to heart-rate monitors housed entirely within a wristwatch, but these require the user to touch a sensor on the watch with a finger. Doing so while jogging, however, likely will lead to an inaccurate reading because you’re moving around so much and the sensors in these devices don’t react well to too much or too little pressure when touched.

These models didn’t make the cut when Electronic Arts Inc., a video game maker with headquarters in Redwood Shores, Calif., decided to include a heart-rate monitor in a sequel to its popular EA Sports Active exercise video game. Instead, the video game company began developing its own HRM that would rely on optical sensors to detect oxygen saturation levels in the user’s bloodstream.

But there was a problem. The motion of blood in a person’s body during exercise—or any significant movement—confuses the oxygen saturation sensor.

Enter Jack McCauley, a consultant for the EA Sports label and founder of ROR3 Devices Inc., a product design and development company based in Livermore, Calif.

McCauley turned to a MEMS-based technology to complete development of the monitor and keep it affordable.

While useful, chest-strap monitors such as this one can be cumbersome for some users, and if they come loose during exercise, the signal is lost. There is no such limitation for the forearm band HRM developed for the EA Sports Active 2 exercise video game (below).

Image courtesy Jack McCauley

“The secret to resolving that issue,” said McCauley, “was to put an accelerometer [3mm × 3mm] in the monitor to tell how a user is moving, because the motion of the blood follows the acceleration in your bloodstream.”

Next, he programmed the device to subtract the oxygen reading from that of the accelerometer data. “We were able to subtract the heart rate from the motion signal,” McCauley explained, noting that tests showed the heart-rate readings were just as accurate as those from chest-strap monitors.

“It’s pretty revolutionary,” observed McCauley, who owns the patent on the technology. The heart-rate monitor—sewn into an elastic strap worn on the forearm—measures 6mm × 4mm. The device works by shining light from two 3.2mm × 1.6mm LEDs into the skin of the user. The light is absorbed by the skin and reflected back into an adjacent optical sensor on a separate 3mm × 3mm silicon die.

Given the deadline to get the Active 2 game completed last year, McCauley noted there was no time to make the monitor even smaller. But it could be done, he added, by placing the accelerometer on the same silicon with the two LEDs and the optical sensor.

While the proprietary heart-rate monitor for Active 2 is programmed to look for certain motion vectors based on the exercises available in the video game, McCauley suggested that the technology could be used in a sports wristwatch programmed with different exercise modes, such as running or jumping jacks.

And with a bit more programming, he said, “you could make the wristwatch intelligent—have it figure out what exercise you’re doing without having to set a particular mode.”

Though McCauley suggested that such a device would have the greatest potential for sales in the sports and fitness market, the technology could find its way into remote patient monitoring devices as well.

“When we were doing the development for the heart-rate monitor for the Active game,” McCauley recalled, “somebody from China approached us and asked, ‘Would you like to produce a product for the Chinese for home health monitoring?’ I told them no. I don’t know enough about that market, and when I asked about all the regulatory issues that would need to be addressed, the person said, ‘We don’t have that problem in China.’ ”

A product like that in the United States, he noted, would be considered a medical device. That said, there is a substantial market for patient monitoring—as much as $9 billion annually in this country, according to The Freedonia Group, a market research firm based in Cleveland.

Meanwhile, the global market for wearable wireless sensors, which includes HRMs, is expected to surpass 400 million devices in 2014, according to ABI Research, a technology market research firm based in Oyster Bay, N.Y. Sales of the devices will be driven by professional health care, the home-health-care sector, and the sports and fitness market, which ABI said accounts for more than 90 percent of current demand.

In-Stat, a technology market research company in Scottsdale, forecasts a compound annual growth rate of nearly 85 percent for Bluetooth-enabled devices in the industrial and medical markets between 2009 and 2014.

“The health and wellness market represents a new and relatively untapped opportunity for Bluetooth,” said Brian O’Rourke, a principal analyst at In-Stat. “The range of equipment includes heart-rate monitors, blood-sugar measurement solutions, exercise and fitness equipment, and much more.”

Meanwhile, total U.S. video game sales surpassed $1 billion in January alone. What’s more, a handful of dance and fitness titles were among the top 20 most popular games sold in January and February.

Altogether, the potential market for this technology should be enough to get your heart pumping. µ