The New Frontier of Wireless Sensing

Still, wireless sensing has come a long way, particularly in the past year or two. The basic concept of smart dust — being able to remotely and wirelessly monitor multiple environmental conditions — is indeed moving into the marketplace. Except, rather than being as small as a speck of dust, the sensors and battery are housed in a package that is currently about the size of a deck of cards. Even so, that's a considerable leap forward from wired systems. Early applications include the reduction of energy costs in buildings; such systems are proving their ability to do just that.

What's been fascinating to watch this past year is how wireless sensing is expanding into an increasingly wide variety of end-use applications. Real-life examples include homeland defense, such as monitoring high-profile sporting events for the detection of biological and chemical agents. Electric utilities are embracing the efficiencies that wireless sensors provide by eliminating the need for visual inspection of machinery. Even some really unique, next-generation weather stations — an array of wireless sensors attached to the nose of small jets — are coming into play.

Most wireless sensing systems employ a variety of sensors to provide data across a range of parameters, but some systems available today monitor just one specific condition. Examples include the use of a moisture sensor in vineyards and on golf courses, or the use of conductive fibers woven into a shirt to monitor heart rate while taking a morning run. Accelerometers can tell you when your breakable object was dropped during shipping, and temperature sensors know if perishable items were stored in conditions that were too hot.

As cool as all of that is, the real innovation is taking place in medicine. Here, sensors are actually being implanted into the body itself. This isn't science fiction or research-level work. Several products were approved by the U.S. Food and Drug Administration (FDA) in early 2006, and include a sensor that monitors the dosage level and effectiveness of radiation therapy in cancer patients, as well as a MEMS sensor implanted into the heart to monitor pressure after a stent is inserted.

In fact, in the case of the latter, this sensor from CardioMEMS (Atlanta) was recently implanted into the wrist of several patients in Chile to monitor severe hypertension. This particular application is not yet FDA-approved, but it offers very interesting repercussions for healthcare as a whole in terms of treatment options. The real question is to what extent might such remote patient monitoring affect the use of pharmaceuticals? Is it a competitive alternative, or a complementary extension of treatment in conjunction with prescription medicine?

Of course, an area of focus for many, many years is the development of implantable sensors for people with diabetes that could monitor blood glucose levels. In fact, researchers and companies alike have moved beyond that to include the automatic delivery of insulin needed. No more sticking your finger multiple times per day. While such a complete system is not quite available, pieces of it are indeed real. This in and of itself is a real achievement. In fact, what I find most striking is that over the past 18 months, nearly all products being developed for the management of diabetes are wireless.

But sensors to monitor diabetes and other medical conditions don't necessarily need to be implanted; applications include the use of watches, skin patches and even clothing. The use of wireless sensing in medicine is growing so quickly that even the Federal Communications Commission (FCC) has taken note, and is already looking into modifying its rules to “accommodate the development and use of a variety of new medical devices that rely on radiocommunication for critical aspects of their functionality.”

While the FCC does already have rules in place for wireless medical technologies, it's good to see that they're proactively recognizing that, with the increased development of more wireless devices, which are increasingly sophisticated, current rules may be inadequate. In this respect, wireless sensing is likely to find a clear path to commercialization in the medical sector.